56 files changed, 10242 insertions, 0 deletions

diff --git a/src/opentracker.c b/src/opentracker.c
new file mode 100644
index 0000000..14b817e
--- /dev/null
+++ b/src/opentracker.c
@@ -0,0 +1,443 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever.
+   Some of the stuff below is stolen from Fefes example libowfat httpd. */
+
+/* System */
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <pthread.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#ifdef WANT_SYSLOGS
+#include <syslog.h>
+#endif
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_config.h"
+#include "ot_hex.h"
+#include "ot_http.h"
+#include "ot_ip.h"
+#include "ot_livesync.h"
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+#include "ot_random.h"
+#include "ot_scan.h"
+#include "ot_event.h"
+#include "ot_fdstate.h"
+#include "ot_socket.h"
+#include "ot_stats.h"
+#include "ot_tcp.h"
+#include "ot_udp.h"
+#include "ot_worker.h"
+#include "trackerlogic.h"
+
+/* Globals */
+uint32_t            g_tracker_id;
+_Atomic int         g_opentracker_running = 1;
+int                 g_self_pipe[2];
+
+static void         panic(const char *routine) __attribute__((noreturn));
+static void         panic(const char *routine) {
+  fprintf(stderr, "%s: %s\n", routine, strerror(errno));
+  exit(111);
+}
+
+/* Say we are stopping, wake the loop, and let main do the work on its own
+   stack. Everything other than SIGINT falls through and does nothing, which
+   is what OT_SIGNAL_WAKE wants: returning from the read is all it is for. */
+static void signal_handler(int s) {
+  if (s == SIGINT) {
+    const char byte  = 0;
+    int        saved = errno;
+
+    /* Any new interrupt signal quits the application */
+    signal(SIGINT, SIG_DFL);
+
+    /* Tell all other threads to not acquire any new lock on a bucket
+       but cancel their operations and return */
+    g_opentracker_running = 0;
+
+    (void)!write(g_self_pipe[1], &byte, 1);
+    errno = saved;
+  }
+}
+
+static void defaul_signal_handlers(void) {
+  sigset_t signal_mask;
+  sigemptyset(&signal_mask);
+  sigaddset(&signal_mask, SIGPIPE);
+  sigaddset(&signal_mask, SIGHUP);
+  sigaddset(&signal_mask, SIGINT);
+  sigaddset(&signal_mask, SIGALRM);
+  pthread_sigmask(SIG_BLOCK, &signal_mask, NULL);
+}
+
+static void install_signal_handlers(void) {
+  struct sigaction sa;
+  sigset_t         signal_mask;
+  sigemptyset(&signal_mask);
+
+  sa.sa_handler = signal_handler;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = 0;
+  if ((sigaction(SIGINT, &sa, NULL) == -1) || (sigaction(SIGALRM, &sa, NULL) == -1) ||
+      (sigaction(OT_SIGNAL_WAKE, &sa, NULL) == -1))
+    panic("install_signal_handlers");
+
+  sigaddset(&signal_mask, SIGINT);
+  pthread_sigmask(SIG_UNBLOCK, &signal_mask, NULL);
+}
+
+
+/* How many ready descriptors one wait hands back at a time */
+#define OT_EVENT_BATCH 512
+
+static void *server_mainloop(void *args) {
+  struct ot_workstruct ws;
+  time_t               next_timeout_check = time_future_seconds(OT_CLIENT_TIMEOUT_CHECKINTERVAL);
+  struct iovec        *iovector;
+  size_t               iovec_entries;
+  int                  is_partial;
+
+  (void)args;
+
+  if (workstruct_init(&ws) == -1)
+    panic("Initializing worker failed");
+
+  while (g_opentracker_running) {
+    ot_event ready[OT_EVENT_BATCH];
+    int64_t  sock;
+    int      count, i;
+
+    count = event_wait(ready, OT_EVENT_BATCH, OT_CLIENT_TIMEOUT_CHECKINTERVAL * 1000);
+
+    for (i = 0; i < count; ++i) {
+      const void *cookie;
+
+      sock = ready[i].fd;
+      /* A descriptor closed earlier in this same batch may already have been
+         handed out again by accept, so an event is only ours if the
+         generation it was registered under is still the one in place */
+      if (fdstate_generation((int)sock) != ready[i].generation)
+        continue;
+      cookie = fdstate_cookie((int)sock);
+
+      if ((intptr_t)cookie == FLAG_TCP)
+        tcp_accept(sock, &ws);
+      else if ((intptr_t)cookie == FLAG_UDP)
+        handle_udp6(sock, &ws);
+      else if ((intptr_t)cookie == FLAG_SELFPIPE)
+        while (read((int)sock, ws.inbuf, G_INBUF_SIZE) > 0)
+          ;
+      else if (fdstate_claim((int)sock, ready[i].generation)) {
+        if (ready[i].what & EVENT_IN)
+          tcp_read(sock, &ws);
+        /* The read may have closed it, so look again before writing */
+        if ((ready[i].what & EVENT_OUT) && fdstate_generation((int)sock) == ready[i].generation)
+          tcp_write(sock);
+        if (fdstate_generation((int)sock) == ready[i].generation)
+          fdstate_release((int)sock);
+      }
+    }
+
+    while ((sock = workqueue_popresult(&iovec_entries, &iovector, &is_partial)) != -1)
+      http_sendiovecdata(sock, &ws, iovec_entries, iovector, is_partial);
+
+    if (time_now_seconds() > next_timeout_check) {
+      int cursor = 0;
+
+      while ((sock = fdstate_next_expired(time_now_seconds(), &cursor)) != -1)
+        http_close(sock);
+      next_timeout_check = time_future_seconds(OT_CLIENT_TIMEOUT_CHECKINTERVAL);
+    }
+
+    livesync_ticker();
+  }
+
+  /* This work struct is about to go out of scope, so hand its tally over
+     before anything can read it there */
+  workstruct_deinit(&ws);
+  return 0;
+}
+
+
+/* A group of sockets sharing one address only spreads datagrams if every
+   member asked for it before binding, the first one included, so whether
+   this entry will have workers has to be known here. */
+static socket_sharing listen_sharing_for(const ot_listen *entry) {
+  if (entry->proto != FLAG_MCA && entry->workers > 1 && socket_can_balance())
+    return SOCKET_BALANCED;
+  return entry->shared ? SOCKET_SHARED : SOCKET_EXCLUSIVE;
+}
+
+static void listen_bind_one(ot_listen *entry) {
+  socket_sharing sharing = listen_sharing_for(entry);
+
+#ifdef _DEBUG
+  {
+    const char *protos[] = {"TCP", "UDP", "UDP mcast"};
+    char  _debug[512];
+    int   off  = snprintf(_debug, sizeof(_debug), "Binding socket type %s to address [", protos[entry->proto]);
+    off       += ip_format(_debug + off, entry->ip);
+    snprintf(_debug + off, sizeof(_debug) - off, "]:%d...", entry->port);
+    fputs(_debug, stderr);
+  }
+#endif
+
+#ifdef WANT_SYNC_LIVE
+  if (entry->proto == FLAG_MCA) {
+    livesync_bind_mcast(entry->ip, entry->port);
+#ifdef _DEBUG
+    fputs(" success.\n", stderr);
+#endif
+    return;
+  }
+#endif
+
+  if (entry->proto == FLAG_TCP) {
+    if ((entry->sock = socket_tcp_listen(entry->ip, entry->port, sharing)) == -1)
+      panic("socket_tcp_listen");
+    socket_defer_accept((int)entry->sock);
+  } else {
+    if ((entry->sock = socket_udp_bind(entry->ip, entry->port, sharing)) == -1)
+      panic("socket_udp_bind");
+  }
+
+  if (event_add((int)entry->sock, EVENT_IN, fdstate_open(entry->sock, (void *)entry->proto, 0)) == -1)
+    panic("event_add");
+
+#ifdef _DEBUG
+  fputs(" success.\n", stderr);
+#endif
+}
+
+/* Bound in the order the entries were given.
+   Note: On macOS SO_REUSEPORT delivers everything to the socket that bound last. */
+static void listen_bind_all(void) {
+  size_t     count, i;
+  ot_listen *entries = config_listen_entries(&count);
+
+  for (i = 0; i < count; ++i)
+    listen_bind_one(entries + i);
+}
+
+/* The socket the event loop was using is passed to the first worker.
+   If start up tests show that the kernel can spread connections over
+   a group bound to one address, every worker binds one of its own.
+   If not, all workers call accept on the first. */
+static void listen_start_tcp_workers(void) {
+  size_t     count, i;
+  ot_listen *entries = config_listen_entries(&count);
+
+  for (i = 0; i < count; ++i) {
+    ot_listen *entry   = entries + i;
+    int        balance = listen_sharing_for(entry) == SOCKET_BALANCED;
+    int        worker;
+
+    if (entry->proto != FLAG_TCP || entry->workers <= 0)
+      continue;
+
+    event_del((int)entry->sock);
+    tcp_worker_install(entry->sock);
+
+    for (worker = 1; worker < entry->workers; ++worker) {
+      int64_t sock = entry->sock;
+
+      if (balance) {
+        sock = socket_tcp_listen(entry->ip, entry->port, SOCKET_BALANCED);
+        if (sock == -1) {
+          fprintf(stderr, "Warning: could not bind another socket for tcp worker %d: %s. Sharing the first instead.\n", worker,
+                  strerror(errno));
+          sock = entry->sock;
+        }
+      }
+      tcp_worker_install(sock);
+    }
+  }
+}
+
+static void listen_start_udp_workers(void) {
+  size_t     count, i;
+  ot_listen *entries = config_listen_entries(&count);
+
+  udp_init();
+
+  for (i = 0; i < count; ++i) {
+    ot_listen *entry   = entries + i;
+    int        balance = listen_sharing_for(entry) == SOCKET_BALANCED;
+    int        worker;
+
+    if (entry->proto != FLAG_UDP || entry->workers <= 0)
+      continue;
+
+    event_del((int)entry->sock);
+    udp_worker_install(entry->sock);
+
+    for (worker = 1; worker < entry->workers; ++worker) {
+      int64_t sock = entry->sock;
+
+      if (balance) {
+        sock = socket_udp_bind(entry->ip, entry->port, SOCKET_BALANCED);
+        if (sock == -1) {
+          fprintf(stderr, "Warning: could not bind another socket for udp worker %d: %s. Sharing the first instead.\n", worker, strerror(errno));
+          sock = entry->sock;
+        }
+      }
+      udp_worker_install(sock);
+    }
+  }
+}
+
+void load_state(const char *const state_filename) {
+  FILE              *state_filehandle;
+  char               inbuf[512];
+  ot_hash  infohash;
+  uint64_t base, downcount;
+  int      consumed;
+
+  state_filehandle = fopen(state_filename, "r");
+
+  if (state_filehandle == NULL) {
+    fprintf(stderr, "Warning: Can't open config file: %s.", state_filename);
+    return;
+  }
+
+  /* We do ignore anything that is not of the form "^[:xdigit:]:\d+:\d+" */
+  while (fgets(inbuf, sizeof(inbuf), state_filehandle)) {
+    size_t i;
+
+    if (!hex_to_hash(infohash, inbuf))
+      continue;
+    i = 2 * sizeof(ot_hash);
+
+    if (inbuf[i++] != ':' || !(consumed = scan_uint(inbuf + i, &base, UINT64_MAX)))
+      continue;
+    i += consumed;
+    if (inbuf[i++] != ':' || !(consumed = scan_uint(inbuf + i, &downcount, UINT64_MAX)))
+      continue;
+    add_torrent_from_saved_state(infohash, base, downcount);
+  }
+
+  fclose(state_filehandle);
+}
+
+int drop_privileges(const char *const serveruser, const char *const serverdir) {
+  struct passwd *pws = NULL;
+
+#ifdef _DEBUG
+  if (!geteuid())
+    fprintf(stderr, "Dropping to user %s.\n", serveruser);
+  if (serverdir)
+    fprintf(stderr, "ch%s'ing to directory %s.\n", geteuid() ? "dir" : "root", serverdir);
+#endif
+
+  /* Grab pws entry before chrooting */
+  pws = getpwnam(serveruser);
+  endpwent();
+
+  if (geteuid() == 0) {
+    /* Running as root: chroot and drop privileges */
+    if (serverdir && chroot(serverdir)) {
+      fprintf(stderr, "Could not chroot to %s, because: %s\n", serverdir, strerror(errno));
+      return -1;
+    }
+
+    if (chdir("/"))
+      panic("chdir() failed after chrooting: ");
+
+    /* If we can't find server user, revert to nobody's default uid */
+    if (!pws) {
+      fprintf(stderr, "Warning: Could not get password entry for %s. Reverting to uid -2.\n", serveruser);
+      if (setegid((gid_t)-2) || setgid((gid_t)-2) || setuid((uid_t)-2) || seteuid((uid_t)-2))
+        panic("Could not set uid to value -2");
+    } else {
+      if (setegid(pws->pw_gid) || setgid(pws->pw_gid) || setuid(pws->pw_uid) || seteuid(pws->pw_uid))
+        panic("Could not set uid to specified value");
+    }
+
+    if (geteuid() == 0 || getegid() == 0)
+      panic("Still running with root privileges?!");
+  } else {
+    /* Normal user, just chdir() */
+    if (serverdir && chdir(serverdir)) {
+      fprintf(stderr, "Could not chroot to %s, because: %s\n", serverdir, strerror(errno));
+      return -1;
+    }
+  }
+
+  return 0;
+}
+
+/* Maintain our copy of the clock. time() on BSDs is very expensive. */
+int main(int argc, char **argv) {
+
+  random_init();
+  if (fdstate_init() == -1)
+    panic("fdstate_init");
+  if (event_init() == -1)
+    panic("event_init");
+  config_parse(argc, argv);
+
+  listen_bind_all();
+
+  defaul_signal_handlers();
+
+#ifdef WANT_SYSLOGS
+  openlog("opentracker", 0, LOG_USER);
+  setlogmask(LOG_UPTO(LOG_INFO));
+#endif
+
+  if (drop_privileges(g_serveruser ? g_serveruser : "nobody", g_serverdir) == -1)
+    panic("drop_privileges failed, exiting. Last error");
+
+
+  /* Create our self pipe which allows us to interrupt mainloops
+     wait in case some data is available to send out */
+  if (pipe(g_self_pipe) == -1)
+    panic("selfpipe failed: ");
+  /* Both ends have to be non blocking: the loop drains the read end until it
+     is empty, and a worker nudging a full pipe has already made its point */
+  socket_set_blocking(g_self_pipe[0], 0);
+  socket_set_blocking(g_self_pipe[1], 0);
+  if (event_add(g_self_pipe[0], EVENT_IN, fdstate_open(g_self_pipe[0], (void *)FLAG_SELFPIPE, 0)) == -1)
+    panic("selfpipe event_add");
+
+  /* Init all sub systems. This call may fail with an exit() */
+  trackerlogic_init();
+
+#ifdef _DEBUG_RANDOMTORRENTS
+  fprintf(stderr, "DEBUG: Generating %d random peers on random torrents. This may take a while. (Setting RANDOMTORRENTS in trackerlogic.h)\n", RANDOMTORRENTS);
+  trackerlogic_add_random_torrents(RANDOMTORRENTS);
+  fprintf(stderr, "... done.\n");
+#endif
+
+  if (g_statefile)
+    load_state(g_statefile);
+
+  install_signal_handlers();
+
+  listen_start_tcp_workers();
+  listen_start_udp_workers();
+
+  server_mainloop(0);
+  worker_stop_all();
+
+  /* No thread is serving any more, so the teardown can run where a debugger
+     and the sanitizers can follow it */
+  trackerlogic_deinit();
+#ifdef WANT_SYSLOGS
+  closelog();
+#endif
+
+  event_deinit();
+  fdstate_deinit();
+  return 0;
+}
diff --git a/src/ot_accesslist.c b/src/ot_accesslist.c
new file mode 100644
index 0000000..86f9a7d
--- /dev/null
+++ b/src/ot_accesslist.c
@@ -0,0 +1,601 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#if defined(WANT_ACCESSLIST_BLACK) || defined(WANT_ACCESSLIST_WHITE)
+#include <fcntl.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#endif
+#ifdef WANT_DYNAMIC_ACCESSLIST
+#include <errno.h>
+#endif
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_hex.h"
+#include "ot_ip.h"
+#include "ot_vector.h"
+#include "trackerlogic.h"
+
+/* GLOBAL VARIABLES */
+#ifdef WANT_ACCESSLIST
+const char *g_accesslist_filename = NULL;
+#ifdef WANT_DYNAMIC_ACCESSLIST
+const char *g_accesslist_pipe_add    = NULL;
+const char *g_accesslist_pipe_delete = NULL;
+#endif
+static pthread_mutex_t g_accesslist_mutex;
+
+/* Accesslists are lock free linked lists. We can not make them locking, because every announce
+   would try to acquire the mutex, making it the most contested mutex in the whole of opentracker,
+   basically creating a central performance choke point.
+
+   The idea is that updating the list heads happens under the g_accesslist_mutex guard and is
+   done atomically, while consumers might potentially still hold pointers deeper inside the list.
+
+   Consumers (for now only via accesslist_hashisvalid) will always fetch the list head pointer
+   that is guaranteed to live for at least five minutes. This should be many orders of magnitudes
+   more than how long it will be needed by the bsearch done on the list. */
+struct ot_accesslist;
+typedef struct ot_accesslist ot_accesslist;
+struct ot_accesslist {
+  ot_hash       *list;
+  size_t         size;
+  ot_time        base;
+  ot_accesslist *next;
+};
+static ot_accesslist *_Atomic g_accesslist = NULL;
+#ifdef WANT_DYNAMIC_ACCESSLIST
+static ot_accesslist *_Atomic g_accesslist_add    = NULL;
+static ot_accesslist *_Atomic g_accesslist_delete = NULL;
+#endif
+
+/* Helpers to work on access lists */
+static int vector_compare_hash(const void *hash1, const void *hash2) { return memcmp(hash1, hash2, OT_HASH_COMPARE_SIZE); }
+
+static ot_accesslist *accesslist_free(ot_accesslist *accesslist) {
+  while (accesslist) {
+    ot_accesslist *this_accesslist = accesslist;
+    accesslist = this_accesslist->next;
+    free(this_accesslist->list);
+    free(this_accesslist);
+  }
+  return NULL;
+}
+
+static ot_accesslist *accesslist_make(ot_accesslist *next, size_t size) {
+  ot_accesslist *accesslist_new = malloc(sizeof(ot_accesslist));
+  if (accesslist_new) {
+    accesslist_new->list = size ? malloc(sizeof(ot_hash) * size) : NULL;
+    accesslist_new->size = size;
+    accesslist_new->base = 0;
+    accesslist_new->next = next;
+    if (size && !accesslist_new->list) {
+      free(accesslist_new);
+      accesslist_new = NULL;
+    }
+  }
+  return accesslist_new;
+}
+
+/* This must be called with g_accesslist_mutex held.
+   This will never delete head, because that might still be in use. */
+static void accesslist_clean(ot_accesslist *accesslist) {
+  while (accesslist && accesslist->next) {
+    if (accesslist->next->base + 5 < time_now_minutes())
+      accesslist->next = accesslist_free(accesslist->next);
+    accesslist = accesslist->next;
+  }
+}
+
+/* A hash needs forty bytes, and all but a final one are followed by at least
+   one separator, so n hashes need at least 41n - 1 bytes. (len + 1) / 41 is
+   therefore an exact upper bound on what a buffer of len bytes can hold. */
+size_t accesslist_parse_hashes(ot_hash *dest, size_t capacity, const char *buf, size_t len) {
+  const char *end   = buf + len;
+  const char *offs  = buf;
+  size_t      count = 0;
+
+  while (count < capacity && end - offs >= 40) {
+    if (hex_to_hash(dest[count], offs)) {
+      offs += 40;
+
+      if (offs == end || !hex_isdigit((unsigned char)*offs))
+        ++count;
+    }
+
+    /* Find start of next line */
+    while (offs < end && *(offs++) != '\n') {}
+  }
+
+  return count;
+}
+
+/* Map a file read only. Returns 0 and sets map and maplen on success, -1 if
+   the file cannot be opened or mapped. */
+static int accesslist_map(const char *filename, const char **map, size_t *maplen) {
+  struct stat st;
+  void       *mapped;
+  int         fd = open(filename, O_RDONLY);
+
+  if (fd < 0)
+    return -1;
+
+  if (fstat(fd, &st) < 0 || st.st_size < 0 || (uintmax_t)st.st_size > (uintmax_t)SIZE_MAX) {
+    close(fd);
+    return -1;
+  }
+
+  if (st.st_size == 0) {
+    close(fd);
+    *map    = NULL;
+    *maplen = 0;
+    return 0;
+  }
+
+  mapped = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_SHARED, fd, 0);
+  close(fd);
+
+  if (mapped == MAP_FAILED)
+    return -1;
+
+  *map    = mapped;
+  *maplen = (size_t)st.st_size;
+  return 0;
+}
+
+static void accesslist_readfile(void) {
+  ot_accesslist *accesslist_new;
+  const char    *map;
+  size_t         maplen, capacity, found;
+
+  if (!g_accesslist_filename)
+    return;
+
+  if (accesslist_map(g_accesslist_filename, &map, &maplen) < 0) {
+    char *wd = getcwd(NULL, 0);
+    fprintf(stderr, "Warning: Can't open accesslist file: %s (but will try to create it later, if necessary and possible).\nPWD: %s\n", g_accesslist_filename, wd);
+    free(wd);
+    return;
+  }
+
+  /* Make room for the most info_hashes this file could possibly hold */
+  capacity       = (maplen + 1) / 41;
+  accesslist_new = accesslist_make(g_accesslist, capacity);
+  if (!accesslist_new) {
+    fprintf(stderr, "Warning: Not enough memory to allocate %zd bytes for accesslist buffer. May succeed later.\n", capacity * sizeof(ot_hash));
+    if (map)
+      munmap((void *)map, maplen);
+    return;
+  }
+
+  found = maplen ? accesslist_parse_hashes(accesslist_new->list, capacity, map, maplen) : 0;
+#ifdef _DEBUG
+  fprintf(stderr, "Added %zd info_hashes to accesslist\n", found);
+#endif
+
+  if (map)
+    munmap((void *)map, maplen);
+
+  if (found)
+    qsort(accesslist_new->list, found, sizeof(ot_hash), vector_compare_hash);
+  accesslist_new->size = found;
+
+  /* Now exchange the accesslist vector in the least race condition prone way */
+  pthread_mutex_lock(&g_accesslist_mutex);
+
+  /* Mark old accesslist as "needs to live another five minutes" */
+  if (g_accesslist)
+    g_accesslist->base = time_now_minutes();
+  accesslist_new->next = g_accesslist;
+  g_accesslist         = accesslist_new; /* Only now set a new list */
+
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  /* If we have dynamic accesslists, reloading a new one will always void the add/delete lists.
+     Insert empty ones at the list head */
+  if (g_accesslist_add && (accesslist_new = accesslist_make(g_accesslist_add, 0)) != NULL) {
+    g_accesslist_add->base = time_now_minutes();
+    g_accesslist_add = accesslist_new;
+  }
+  if (g_accesslist_delete && (accesslist_new = accesslist_make(g_accesslist_delete, 0)) != NULL) {
+    g_accesslist_delete->base = time_now_minutes();
+    g_accesslist_delete = accesslist_new;
+  }
+#endif
+
+  accesslist_clean(g_accesslist);
+
+  pthread_mutex_unlock(&g_accesslist_mutex);
+}
+
+int accesslist_hashisvalid(const ot_hash hash) {
+  /* Get working copy of current access list */
+  ot_accesslist *accesslist = g_accesslist;
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  ot_accesslist *accesslist_add, *accesslist_delete;
+#endif
+  void *exactmatch = NULL;
+
+  if (accesslist && accesslist->size)
+    exactmatch = bsearch(hash, accesslist->list, accesslist->size, OT_HASH_COMPARE_SIZE, vector_compare_hash);
+
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  /* If we had no match on the main list, scan the list of dynamically added hashes */
+  accesslist_add = g_accesslist_add;
+  if ((exactmatch == NULL) && accesslist_add && accesslist_add->size)
+    exactmatch = bsearch(hash, accesslist_add->list, accesslist_add->size, OT_HASH_COMPARE_SIZE, vector_compare_hash);
+
+  /* If we found a matching hash on the main list, scan the list of dynamically deleted hashes */
+  accesslist_delete = g_accesslist_delete;
+  if ((exactmatch != NULL) && accesslist_delete && accesslist_delete->size && bsearch(hash, accesslist_delete->list, accesslist_delete->size, OT_HASH_COMPARE_SIZE, vector_compare_hash))
+    exactmatch = NULL;
+#endif
+
+#ifdef WANT_ACCESSLIST_BLACK
+  return exactmatch == NULL;
+#else
+  return exactmatch != NULL;
+#endif
+}
+
+static void *accesslist_worker(void *args) {
+  int      sig;
+  sigset_t signal_mask;
+
+  sigemptyset(&signal_mask);
+  sigaddset(&signal_mask, SIGHUP);
+
+  (void)args;
+
+  while (1) {
+    if (!g_opentracker_running)
+      return NULL;
+
+    /* Initial attempt to read accesslist */
+    accesslist_readfile();
+
+    /* Wait for signals */
+    while (sigwait(&signal_mask, &sig) != 0 && sig != SIGHUP)
+      ;
+  }
+  return NULL;
+}
+
+#ifdef WANT_DYNAMIC_ACCESSLIST
+static pthread_t   thread_adder_id, thread_deleter_id;
+static _Atomic int adder_left, deleter_left;
+static void     *accesslist_adddel_worker(const char *fifoname, ot_accesslist *_Atomic *adding_to, ot_accesslist *_Atomic *removing_from) {
+  struct stat st;
+
+  if (!stat(fifoname, &st)) {
+    if (!S_ISFIFO(st.st_mode)) {
+      fprintf(stderr, "Error when starting dynamic accesslists: Found Non-FIFO file at %s.\nPlease remove it and restart opentracker.\n", fifoname);
+      return NULL;
+    }
+  } else {
+    int error = mkfifo(fifoname, 0755);
+    if (error && error != EEXIST) {
+      fprintf(stderr, "Error when starting dynamic accesslists: Couldn't create FIFO at %s, error: %s\n", fifoname, strerror(errno));
+      return NULL;
+    }
+  }
+
+  while (g_opentracker_running) {
+    FILE   *fifo    = fopen(fifoname, "r");
+    char   *line    = NULL;
+    size_t  linecap = 0;
+    ssize_t linelen;
+
+    if (!fifo) {
+      /* Woken on purpose: the loop condition above decides what happens next */
+      if (errno == EINTR)
+        continue;
+      fprintf(stderr, "Error when reading dynamic accesslists: Couldn't open FIFO at %s, error: %s\n", fifoname, strerror(errno));
+      return NULL;
+    }
+
+    while ((linelen = getline(&line, &linecap, fifo)) > 0) {
+      ot_hash info_hash;
+
+      printf("Got line %*s", (int)linelen, line);
+      /* We do ignore anything that is not of the form "^[:xdigit:]{40}[^:xdigit:].*"
+        If there's not enough characters for an info_hash in the line, skip it. */
+      if (linelen < 41)
+        continue;
+
+      if (!hex_to_hash(info_hash, line))
+        continue;
+
+      /* From now on we modify g_accesslist_add and g_accesslist_delete, so prevent the
+         other worker threads from doing the same */
+      pthread_mutex_lock(&g_accesslist_mutex);
+
+      /* If the info hash is in the removing_from list, create a new head without that entry */
+      if (*removing_from && (*removing_from)->list) {
+        ot_hash *exactmatch = bsearch(info_hash, (*removing_from)->list, (*removing_from)->size, OT_HASH_COMPARE_SIZE, vector_compare_hash);
+        if (exactmatch) {
+          ptrdiff_t      off            = exactmatch - (*removing_from)->list;
+          ot_accesslist *accesslist_new = accesslist_make(*removing_from, (*removing_from)->size - 1);
+          if (accesslist_new) {
+            size_t after = (*removing_from)->size - off - 1;
+
+            /* Removing the only entry leaves a list with no room at all, and
+               memcpy may not be handed that even for nothing */
+            if (off)
+              memcpy(accesslist_new->list, (*removing_from)->list, sizeof(ot_hash) * off);
+            if (after)
+              memcpy(accesslist_new->list + off, (*removing_from)->list + off + 1, sizeof(ot_hash) * after);
+            (*removing_from)->base = time_now_minutes();
+            *removing_from = accesslist_new;
+          }
+        }
+      }
+
+      /* Simple case: there's no adding_to list yet, create one with one member */
+      if (!*adding_to) {
+        ot_accesslist *accesslist_new = accesslist_make(NULL, 1);
+        if (accesslist_new) {
+          memcpy(accesslist_new->list, info_hash, sizeof(ot_hash));
+          *adding_to = accesslist_new;
+        }
+      } else {
+        int exactmatch   = 0;
+        ot_hash *insert_point = vector_binary_search(info_hash, (*adding_to)->list, (*adding_to)->size, sizeof(ot_hash), OT_HASH_COMPARE_SIZE, &exactmatch);
+
+        /* Only if the info hash is not in the adding_to list, create a new head with that entry */
+        if (!exactmatch) {
+          ot_accesslist *accesslist_new = accesslist_make(*adding_to, (*adding_to)->size + 1);
+          ptrdiff_t      off            = insert_point - (*adding_to)->list;
+          if (accesslist_new) {
+            memcpy(accesslist_new->list, (*adding_to)->list, sizeof(ot_hash) * off);
+            memcpy(accesslist_new->list + off, info_hash, sizeof(info_hash));
+            memcpy(accesslist_new->list + off + 1, (*adding_to)->list + off, sizeof(ot_hash) * ((*adding_to)->size - off));
+            (*adding_to)->base = time_now_minutes();
+            *adding_to = accesslist_new;
+          }
+        }
+      }
+
+      pthread_mutex_unlock(&g_accesslist_mutex);
+    }
+
+    free(line);
+    fclose(fifo);
+  }
+  return NULL;
+}
+
+static void *accesslist_adder_worker(void *args) {
+  (void)args;
+  accesslist_adddel_worker(g_accesslist_pipe_add, &g_accesslist_add, &g_accesslist_delete);
+  atomic_store(&adder_left, 1);
+  return NULL;
+}
+static void *accesslist_deleter_worker(void *args) {
+  (void)args;
+  accesslist_adddel_worker(g_accesslist_pipe_delete, &g_accesslist_delete, &g_accesslist_add);
+  atomic_store(&deleter_left, 1);
+  return NULL;
+}
+
+/* These sit in a blocking open or read on a FIFO, so they are woken the way
+   the other workers are, and the signal is repeated because it only
+   interrupts a call already under way. The pipe name is what says whether
+   the thread was ever started. */
+static void accesslist_stop_fifo_worker(pthread_t thread, _Atomic int *left, const char *pipe_name) {
+  if (!pipe_name)
+    return;
+
+  while (!atomic_load(left)) {
+    pthread_kill(thread, OT_SIGNAL_WAKE);
+    usleep(1000);
+  }
+  pthread_join(thread, NULL);
+}
+#endif
+
+static pthread_t thread_id;
+void accesslist_init(void) {
+  pthread_mutex_init(&g_accesslist_mutex, NULL);
+  pthread_create(&thread_id, NULL, accesslist_worker, NULL);
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  if (g_accesslist_pipe_add)
+    pthread_create(&thread_adder_id, NULL, accesslist_adder_worker, NULL);
+  if (g_accesslist_pipe_delete)
+    pthread_create(&thread_deleter_id, NULL, accesslist_deleter_worker, NULL);
+#endif
+}
+
+void accesslist_deinit(void) {
+  /* Wake the worker and wait for it to notice that the tracker is stopping. */
+  pthread_kill(thread_id, SIGHUP);
+  pthread_join(thread_id, NULL);
+
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  /* Before the lists they are reading are freed below */
+  accesslist_stop_fifo_worker(thread_adder_id, &adder_left, g_accesslist_pipe_add);
+  accesslist_stop_fifo_worker(thread_deleter_id, &deleter_left, g_accesslist_pipe_delete);
+#endif
+
+  pthread_mutex_lock(&g_accesslist_mutex);
+
+  g_accesslist = accesslist_free(g_accesslist);
+
+#ifdef WANT_DYNAMIC_ACCESSLIST
+  g_accesslist_add    = accesslist_free(g_accesslist_add);
+  g_accesslist_delete = accesslist_free(g_accesslist_delete);
+#endif
+
+  pthread_mutex_unlock(&g_accesslist_mutex);
+  pthread_mutex_destroy(&g_accesslist_mutex);
+}
+
+void accesslist_cleanup(void) {
+  pthread_mutex_lock(&g_accesslist_mutex);
+
+  accesslist_clean(g_accesslist);
+#if WANT_DYNAMIC_ACCESSLIST
+  accesslist_clean(g_accesslist_add);
+  accesslist_clean(g_accesslist_delete);
+#endif
+
+  pthread_mutex_unlock(&g_accesslist_mutex);
+}
+#endif
+
+int accesslist_address_in_net(const ot_ip6 address, const ot_net *net) {
+  int bits = net->bits, checkbits = (0x7f00 >> (bits & 7));
+  int result = memcmp(address, &net->address, bits >> 3);
+  if (!result && (bits & 7))
+    result = (checkbits & address[bits >> 3]) - (checkbits & net->address[bits >> 3]);
+  return result == 0;
+}
+
+void *accesslist_set_value_for_net(const ot_net *net, ot_vector *vector, const void *value, const size_t member_size) {
+  size_t i;
+  int    exactmatch;
+
+  /* Caller must have a concept of ot_net in it's member */
+  if (member_size < sizeof(ot_net))
+    return 0;
+
+  /* Check each net in vector for overlap */
+  uint8_t *member = ((uint8_t *)vector->data);
+  for (i = 0; i < vector->size; ++i) {
+    if (accesslist_address_in_net(*(ot_ip6 *)member, net) || accesslist_address_in_net(net->address, (ot_net *)member))
+      return 0;
+    member += member_size;
+  }
+
+  member = vector_find_or_insert(vector, (void *)net, member_size, sizeof(ot_net), &exactmatch);
+  if (member) {
+    memcpy(member, net, sizeof(ot_net));
+    memcpy(member + sizeof(ot_net), value, member_size - sizeof(ot_net));
+  }
+
+  return member;
+}
+
+/* Takes a vector filled with { ot_net net, uint8_t[x] value };
+   Returns value associated with the net, or NULL if not found */
+void *accesslist_get_value_for_net(const ot_ip6 address, const ot_vector *vector, const size_t member_size) {
+  int     exactmatch;
+  /* This binary search will return a pointer to the first non-containing network... */
+  ot_net *net = vector_binary_search(address, vector->data, vector->size, member_size, sizeof(ot_ip6), &exactmatch);
+  if (!net)
+    return NULL;
+  /* ... so we'll need to move back one step unless we've exactly hit the first address in network */
+  if (!exactmatch && ((void *)net > vector->data))
+    --net;
+  if (!accesslist_address_in_net(address, net))
+    return NULL;
+  return (void *)net;
+}
+
+#ifdef WANT_IP_FROM_PROXY
+typedef struct {
+  ot_net   *proxy;
+  ot_vector networks;
+} ot_proxymap;
+
+static ot_vector       g_proxies_list;
+static pthread_mutex_t g_proxies_list_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+int proxylist_add_network(const ot_net *proxy, const ot_net *net) {
+  ot_proxymap *map;
+  int exactmatch, result = 1;
+  pthread_mutex_lock(&g_proxies_list_mutex);
+
+  /* If we have a direct hit, use and extend the vector there */
+  map = vector_binary_search(proxy, g_proxies_list.data, g_proxies_list.size, sizeof(ot_proxymap), sizeof(ot_net), &exactmatch);
+
+  if (!map || !exactmatch) {
+    /* else see, if we've got overlapping networks
+       and get a new empty vector if not */
+    ot_vector empty;
+    memset(&empty, 0, sizeof(ot_vector));
+    map = accesslist_set_value_for_net(proxy, &g_proxies_list, &empty, sizeof(ot_proxymap));
+  }
+
+  if (map && accesslist_set_value_for_net(net, &map->networks, NULL, sizeof(ot_net)))
+    result = 1;
+
+  pthread_mutex_unlock(&g_proxies_list_mutex);
+  return result;
+}
+
+int proxylist_check_proxy(const ot_ip6 proxy, const ot_ip6 address) {
+  int result = 0;
+  ot_proxymap *map;
+
+  pthread_mutex_lock(&g_proxies_list_mutex);
+
+  if ((map = accesslist_get_value_for_net(proxy, &g_proxies_list, sizeof(ot_proxymap))))
+    if (!address || accesslist_get_value_for_net(address, &map->networks, sizeof(ot_net)))
+      result = 1;
+
+  pthread_mutex_unlock(&g_proxies_list_mutex);
+  return result;
+}
+
+#endif
+
+static ot_net         g_admin_nets[OT_ADMINIP_MAX];
+static ot_permissions g_admin_nets_permissions[OT_ADMINIP_MAX];
+static size_t         g_admin_nets_count = 0;
+
+int accesslist_bless_net(ot_net *net, ot_permissions permissions) {
+  if (g_admin_nets_count >= OT_ADMINIP_MAX)
+    return -1;
+
+  memcpy(g_admin_nets + g_admin_nets_count, net, sizeof(ot_net));
+  g_admin_nets_permissions[g_admin_nets_count++] = permissions;
+
+#ifdef _DEBUG
+  {
+    char _debug[512];
+    int  off  = snprintf(_debug, sizeof(_debug), "Blessing ip net ");
+    off      += ip_format(_debug + off, net->address);
+    if (net->bits < 128) {
+      _debug[off++] = '/';
+      if (ip_is_v4mapped(net->address))
+        off += snprintf(_debug + off, sizeof(_debug) - off, "%d", net->bits - 96);
+      else
+        off += snprintf(_debug + off, sizeof(_debug) - off, "%d", net->bits);
+    }
+
+    if (permissions & OT_PERMISSION_MAY_STAT)
+      off += snprintf(_debug + off, 512 - off, " may_fetch_stats");
+    if (permissions & OT_PERMISSION_MAY_LIVESYNC)
+      off += snprintf(_debug + off, 512 - off, " may_sync_live");
+    if (permissions & OT_PERMISSION_MAY_FULLSCRAPE)
+      off += snprintf(_debug + off, 512 - off, " may_fetch_fullscrapes");
+    if (permissions & OT_PERMISSION_MAY_PROXY)
+      off += snprintf(_debug + off, 512 - off, " may_proxy");
+    if (!permissions)
+      off += snprintf(_debug + off, sizeof(_debug) - off, " nothing");
+    _debug[off++] = '.';
+    _debug[off++] = '\n';
+    (void)write(2, _debug, off);
+  }
+#endif
+
+  return 0;
+}
+
+int accesslist_is_blessed(ot_ip6 ip, ot_permissions permissions) {
+  size_t i;
+  for (i = 0; i < g_admin_nets_count; ++i)
+    if (accesslist_address_in_net(ip, g_admin_nets + i) && (g_admin_nets_permissions[i] & permissions))
+      return 1;
+  return 0;
+}
diff --git a/src/ot_accesslist.h b/src/ot_accesslist.h
new file mode 100644
index 0000000..68c88dc
--- /dev/null
+++ b/src/ot_accesslist.h
@@ -0,0 +1,77 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_ACCESSLIST_H__
+#define OT_ACCESSLIST_H__
+
+#include "trackerlogic.h"
+
+#if defined(WANT_ACCESSLIST_BLACK) && defined(WANT_ACCESSLIST_WHITE)
+#error WANT_ACCESSLIST_BLACK and WANT_ACCESSLIST_WHITE are exclusive.
+#endif
+
+#if defined(WANT_ACCESSLIST_BLACK) || defined(WANT_ACCESSLIST_WHITE)
+#define WANT_ACCESSLIST
+/* Starts a thread that rereads the list when sent SIGHUP, and is stopped by
+   being sent one, so the caller blocks SIGHUP process wide beforehand */
+void         accesslist_init(void);
+void         accesslist_deinit(void);
+int          accesslist_hashisvalid(const ot_hash hash);
+void         accesslist_cleanup(void);
+
+/* Scan buf for up to capacity info_hashes in hexadecimal notation, one per
+   line, and return how many were written to dest */
+size_t       accesslist_parse_hashes(ot_hash *dest, size_t capacity, const char *buf, size_t len);
+
+extern const char *g_accesslist_filename;
+#ifdef WANT_DYNAMIC_ACCESSLIST
+extern const char *g_accesslist_pipe_add;
+extern const char *g_accesslist_pipe_delete;
+#endif
+
+#else
+#ifdef WANT_DYNAMIC_ACCESSLIST
+#error WANT_DYNAMIC_ACCESSLIST needs either WANT_ACCESSLIST_BLACK or WANT_ACCESSLIST_WHITE
+#endif
+
+#define accesslist_init(accesslist_filename)
+#define accesslist_deinit()
+#define accesslist_hashisvalid(hash) 1
+#endif
+
+/* Test if an address is subset of an ot_net, return value is considered a bool */
+int   accesslist_address_in_net(const ot_ip6 address, const ot_net *net);
+
+/* Store a value into a vector of struct { ot_net net, uint8_t[x] value } member;
+   returns NULL
+     if member_size is too small, or
+     if one of the nets inside the vector are a subnet of _net_, or
+     if _net_ is a subnet of one of the nets inside the vector, or
+     if the vector could not be resized
+   returns pointer to new member in vector for success
+   member_size can be sizeof(ot_net) to reduce the lookup to a boolean mapping
+*/
+void *accesslist_set_value_for_net(const ot_net *net, ot_vector *vector, const void *value, const size_t member_size);
+
+/* Takes a vector filled with struct { ot_net net, uint8_t[x] value } member;
+   Returns pointer to _member_ associated with the net, or NULL if not found
+   member_size can be sizeof(ot_net) to reduce the lookup to a boolean mapping
+*/
+void *accesslist_get_value_for_net(const ot_ip6 address, const ot_vector *vector, const size_t member_size);
+
+#ifdef WANT_IP_FROM_PROXY
+int proxylist_add_network(const ot_net *proxy, const ot_net *net);
+int proxylist_check_network(const ot_ip6 *proxy, const ot_ip6 address /* can be NULL to only check proxy */);
+#endif
+
+typedef enum {
+  OT_PERMISSION_MAY_FULLSCRAPE = 0x1,
+  OT_PERMISSION_MAY_STAT       = 0x2,
+  OT_PERMISSION_MAY_LIVESYNC   = 0x4,
+  OT_PERMISSION_MAY_PROXY      = 0x8
+} ot_permissions;
+
+int accesslist_bless_net(ot_net *net, ot_permissions permissions);
+int accesslist_is_blessed(ot_ip6 ip, ot_permissions permissions);
+
+#endif
diff --git a/src/ot_batch.c b/src/ot_batch.c
new file mode 100644
index 0000000..e4dda0b
--- /dev/null
+++ b/src/ot_batch.c
@@ -0,0 +1,156 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_batch.h"
+
+#ifndef IOV_MAX
+#define IOV_MAX 1024
+#endif
+
+#define OT_BATCH_MIN_ENTRIES 16
+
+static int batch_room_for(ot_batch *batch, size_t wanted) {
+  size_t        space = batch->space ? batch->space : OT_BATCH_MIN_ENTRIES;
+  struct iovec *grown;
+
+  if (batch->count + wanted <= batch->space)
+    return 0;
+
+  /* During a chunked transfer entries are appended while earlier ones are
+     still going out, so the front of the array frees up as we go. Slide the
+     rest down before asking for more. */
+  if (batch->first && batch->count - batch->first + wanted <= batch->space) {
+    memmove(batch->entries, batch->entries + batch->first, (batch->count - batch->first) * sizeof(struct iovec));
+    batch->count -= batch->first;
+    batch->first  = 0;
+    return 0;
+  }
+
+  while (space < batch->count + wanted)
+    space *= 2;
+
+  if (!(grown = realloc(batch->entries, space * sizeof(struct iovec))))
+    return -1;
+
+  batch->entries = grown;
+  batch->space   = space;
+  return 0;
+}
+
+int batch_add(ot_batch *batch, void *buf, size_t len) {
+  if (batch_room_for(batch, 1)) {
+    free(buf);
+    return -1;
+  }
+
+  batch->entries[batch->count].iov_base = buf;
+  batch->entries[batch->count].iov_len  = len;
+  ++batch->count;
+  return 0;
+}
+
+int batch_add_vector(ot_batch *batch, const struct iovec *entries, size_t count) {
+  if (batch_room_for(batch, count)) {
+    while (count--)
+      free(entries[count].iov_base);
+    return -1;
+  }
+
+  memcpy(batch->entries + batch->count, entries, count * sizeof(struct iovec));
+  batch->count += count;
+  return 0;
+}
+
+/* Drop everything the kernel accepted, freeing each buffer as it goes */
+static void batch_consume(ot_batch *batch, size_t written) {
+  while (written) {
+    struct iovec *entry = batch->entries + batch->first;
+    size_t        left  = entry->iov_len - batch->offset;
+
+    if (written < left) {
+      batch->offset += written;
+      return;
+    }
+
+    free(entry->iov_base);
+    written      -= left;
+    batch->offset = 0;
+    ++batch->first;
+  }
+
+  /* Nothing is outstanding, so the array can start over from the front */
+  if (batch->first == batch->count)
+    batch->first = batch->count = 0;
+}
+
+/* A peer that has gone away must come back as an error rather than as a
+   signal that kills the tracker, so ask the kernel not to raise one where it
+   can be asked. macOS cannot, and relies on SIGPIPE being blocked. */
+static ssize_t batch_writev(int s, struct iovec *entries, int count) {
+#ifdef MSG_NOSIGNAL
+  struct msghdr msg;
+
+  memset(&msg, 0, sizeof(msg));
+  msg.msg_iov    = entries;
+  msg.msg_iovlen = count;
+  return sendmsg(s, &msg, MSG_NOSIGNAL);
+#else
+  return writev(s, entries, count);
+#endif
+}
+
+ssize_t batch_send(int s, ot_batch *batch) {
+  size_t  entries = batch->count - batch->first;
+  ssize_t written;
+
+  if (!batch_pending(batch))
+    return BATCH_DONE;
+
+  if (entries > IOV_MAX)
+    entries = IOV_MAX;
+
+  /* The first entry may be half way out already */
+  batch->entries[batch->first].iov_base = (char *)batch->entries[batch->first].iov_base + batch->offset;
+  batch->entries[batch->first].iov_len -= batch->offset;
+  written                               = batch_writev(s, batch->entries + batch->first, (int)entries);
+  batch->entries[batch->first].iov_base = (char *)batch->entries[batch->first].iov_base - batch->offset;
+  batch->entries[batch->first].iov_len += batch->offset;
+
+  if (written < 0)
+    return (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) ? BATCH_AGAIN : BATCH_FAILED;
+  if (!written)
+    return BATCH_FAILED;
+
+  batch_consume(batch, (size_t)written);
+  return written;
+}
+
+void batch_reset(ot_batch *batch) {
+  while (batch->first < batch->count)
+    free(batch->entries[batch->first++].iov_base);
+
+  free(batch->entries);
+  batch->entries   = NULL;
+  batch->count = batch->first = batch->offset = batch->space = 0;
+}
+
+/* For the few constants the chunked encoding needs, which the batch frees
+   along with everything else */
+int batch_add_copy(ot_batch *batch, const void *buf, size_t len) {
+  void *copy = malloc(len);
+
+  if (!copy)
+    return -1;
+  memcpy(copy, buf, len);
+  return batch_add(batch, copy, len);
+}
diff --git a/src/ot_batch.h b/src/ot_batch.h
new file mode 100644
index 0000000..910bea7
--- /dev/null
+++ b/src/ot_batch.h
@@ -0,0 +1,46 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_BATCH_H__
+#define OT_BATCH_H__
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+
+/* A queue of buffers on their way to one socket. The batch owns every buffer
+   handed to it and frees each one as soon as it has left, so a client that
+   reads slowly costs memory only for what it has not received yet.
+
+   A zeroed ot_batch is ready to use. */
+typedef struct {
+  struct iovec *entries;
+  size_t        space;
+  size_t        count;
+  size_t        first;  /* entries before this one are sent and freed */
+  size_t        offset; /* bytes of entries[first] already sent */
+} ot_batch;
+
+static inline int batch_pending(const ot_batch *batch) { return batch->first != batch->count; }
+
+/* What batch_send reports instead of a byte count */
+enum { BATCH_DONE = 0, BATCH_AGAIN = -1, BATCH_FAILED = -2 };
+
+/* Queue buf and take ownership of it. Returns 0, or -1 having freed buf. */
+int     batch_add(ot_batch *batch, void *buf, size_t len);
+
+/* Write as much as the socket takes. Returns the number of bytes written, or
+   BATCH_DONE, BATCH_AGAIN or BATCH_FAILED. */
+ssize_t batch_send(int s, ot_batch *batch);
+
+/* Queue every entry of a vector, taking ownership of each buffer but not of
+   the vector itself. Returns 0, or -1 having freed all of them. */
+int     batch_add_vector(ot_batch *batch, const struct iovec *entries, size_t count);
+
+/* Queue a copy of buf, which the batch then owns. Returns 0, or -1. */
+int     batch_add_copy(ot_batch *batch, const void *buf, size_t len);
+
+/* Free whatever has not left yet, along with the batch's own array */
+void    batch_reset(ot_batch *batch);
+
+#endif
diff --git a/src/ot_buf.c b/src/ot_buf.c
new file mode 100644
index 0000000..ecd3f8d
--- /dev/null
+++ b/src/ot_buf.c
@@ -0,0 +1,39 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdlib.h>
+#include <string.h>
+
+/* Opentracker */
+#include "ot_buf.h"
+
+int buf_cat(ot_buf *buf, const void *src, size_t len) {
+  char *data;
+
+  if (!len)
+    return 0;
+
+  if (buf->size + len < buf->size)
+    return -1;
+
+  if (!(data = realloc(buf->data, buf->size + len)))
+    return -1;
+
+  buf->data = data;
+  memcpy(data + buf->size, src, len);
+  buf->size += len;
+
+  return 0;
+}
+
+void buf_truncate(ot_buf *buf, size_t len) {
+  if (len < buf->size)
+    buf->size = len;
+}
+
+void buf_reset(ot_buf *buf) {
+  free(buf->data);
+  buf->data = NULL;
+  buf->size = 0;
+}
diff --git a/src/ot_buf.h b/src/ot_buf.h
new file mode 100644
index 0000000..7fb944e
--- /dev/null
+++ b/src/ot_buf.h
@@ -0,0 +1,25 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_BUF_H__
+#define OT_BUF_H__
+
+#include <stddef.h>
+
+/* A growable byte buffer, holding an HTTP request that did not arrive in a
+   single packet. Requests that arrive whole are served straight from the
+   worker's input buffer and never come near this. */
+typedef struct {
+  char  *data;
+  size_t size;
+} ot_buf;
+
+/* Append len bytes from src. Returns 0, or -1 if the memory could not be
+   had, in which case the buffer keeps whatever it already held. */
+int buf_cat(ot_buf *buf, const void *src, size_t len);
+
+void buf_truncate(ot_buf *buf, size_t len);
+
+void buf_reset(ot_buf *buf);
+
+#endif
diff --git a/src/ot_clean.c b/src/ot_clean.c
new file mode 100644
index 0000000..f181e83
--- /dev/null
+++ b/src/ot_clean.c
@@ -0,0 +1,176 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <pthread.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_clean.h"
+#include "ot_mutex.h"
+#include "ot_stats.h"
+#include "ot_vector.h"
+#include "trackerlogic.h"
+
+/* Returns amount of removed peers */
+static ssize_t clean_single_bucket(ot_peer *peers, size_t peer_count, size_t peer_size, time_t timedout, size_t *removed_seeders) {
+  ot_peer *last_peer = peers + peer_count * peer_size, *insert_point;
+
+  /* Two scan modes: unless there is one peer removed, just increase ot_peertime */
+  while (peers < last_peer) {
+    time_t timediff = timedout + OT_PEERTIME(peers, peer_size);
+    if (timediff >= OT_PEER_TIMEOUT)
+      break;
+    OT_PEERTIME(peers, peer_size)  = timediff;
+    peers += peer_size;
+  }
+
+  /* If we at least remove one peer, we have to copy */
+  for (insert_point = peers; peers < last_peer; peers += peer_size) {
+    time_t timediff = timedout + OT_PEERTIME(peers, peer_size);
+
+    if (timediff < OT_PEER_TIMEOUT) {
+      OT_PEERTIME(peers, peer_size) = timediff;
+      memcpy(insert_point, peers, peer_size);
+      insert_point += peer_size;
+    } else if (OT_PEERFLAG_D(peers, peer_size) & PEER_FLAG_SEEDING)
+      (*removed_seeders)++;
+  }
+
+  return (peers - insert_point) / peer_size;
+}
+
+int clean_single_peer_list(ot_peerlist *peer_list, size_t peer_size) {
+  ot_vector *peer_vector = &peer_list->peers;
+  time_t     timedout    = (time_t)(time_now_minutes() - peer_list->base);
+  size_t     num_buckets = 1, removed_seeders = 0;
+
+  /* No need to clean empty torrent */
+  if (!timedout)
+    return 0;
+
+  /* Torrent has idled out */
+  if (timedout > OT_TORRENT_TIMEOUT)
+    return 1;
+
+  /* Nothing to be cleaned here? Test if torrent is worth keeping */
+  if (timedout > OT_PEER_TIMEOUT) {
+    if (!peer_list->peer_count)
+      return peer_list->down_count ? 0 : 1;
+    timedout = OT_PEER_TIMEOUT;
+  }
+
+  if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+    num_buckets = peer_vector->size;
+    peer_vector = (ot_vector *)peer_vector->data;
+  }
+
+  while (num_buckets--) {
+    size_t removed_peers   = clean_single_bucket(peer_vector->data, peer_vector->size, peer_size, timedout, &removed_seeders);
+    peer_list->peer_count -= removed_peers;
+    peer_vector->size     -= removed_peers;
+    if (removed_peers)
+      vector_fixup_peers(peer_vector, peer_size);
+
+    /* Skip to next bucket, a vector containing peers */
+    ++peer_vector;
+  }
+
+  peer_list->seed_count -= removed_seeders;
+
+  /* See if we need to convert a torrent from simple vector to bucket list */
+  if ((peer_list->peer_count > OT_PEER_BUCKET_MINCOUNT) || OT_PEERLIST_HASBUCKETS(peer_list))
+    vector_redistribute_buckets(peer_list, peer_size);
+
+  if (peer_list->peer_count)
+    peer_list->base = time_now_minutes();
+  else {
+    /* When we got here, the last time that torrent
+     has been touched is OT_PEER_TIMEOUT Minutes before */
+    peer_list->base = time_now_minutes() - OT_PEER_TIMEOUT;
+  }
+  return 0;
+}
+
+/* Clean a single torrent
+   return 1 if torrent timed out
+*/
+int clean_single_torrent(ot_torrent *torrent) {
+  return clean_single_peer_list(torrent->peer_list6, OT_PEER_SIZE6) * clean_single_peer_list(torrent->peer_list4, OT_PEER_SIZE4);
+}
+
+static pthread_mutex_t g_clean_mutex  = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t  g_clean_wakeup = PTHREAD_COND_INITIALIZER;
+
+static void clean_sleep(void) {
+  struct timespec deadline;
+
+  clock_gettime(CLOCK_REALTIME, &deadline);
+  deadline.tv_sec  += OT_CLEAN_SLEEP / 1000000;
+  deadline.tv_nsec += (OT_CLEAN_SLEEP % 1000000) * 1000;
+  if (deadline.tv_nsec >= 1000000000) {
+    ++deadline.tv_sec;
+    deadline.tv_nsec -= 1000000000;
+  }
+
+  /* Both sides hold the mutex, so the flag cannot be cleared and signalled
+     in the window between testing it and waiting on it */
+  pthread_mutex_lock(&g_clean_mutex);
+  while (g_opentracker_running)
+    if (pthread_cond_timedwait(&g_clean_wakeup, &g_clean_mutex, &deadline) == ETIMEDOUT)
+      break;
+  pthread_mutex_unlock(&g_clean_mutex);
+}
+
+/* Clean up all peers in one bucket, remove timedout pools and torrents */
+static void clean_bucket(size_t bucket) {
+  ot_vector *torrents_list = mutex_bucket_lock((int)bucket);
+  size_t     toffs;
+  int        delta_torrentcount = 0;
+
+  for (toffs = 0; toffs < torrents_list->size; ++toffs) {
+    ot_torrent *torrent = ((ot_torrent *)(torrents_list->data)) + toffs;
+    if (clean_single_torrent(torrent)) {
+      vector_remove_torrent(torrents_list, torrent);
+      --delta_torrentcount;
+      --toffs;
+    }
+  }
+  mutex_bucket_unlock((int)bucket, delta_torrentcount);
+}
+
+static void *clean_worker(void *args) {
+  (void)args;
+  while (1) {
+    size_t bucket = OT_BUCKET_COUNT;
+    while (bucket) {
+      size_t todo = bucket < OT_CLEAN_BUCKETS_PER_WAKE ? bucket : OT_CLEAN_BUCKETS_PER_WAKE;
+
+      /* One bucket is locked at a time, however many a wake gets through */
+      while (todo--)
+        clean_bucket(--bucket);
+
+      if (!g_opentracker_running)
+        return NULL;
+      clean_sleep();
+    }
+    stats_cleanup();
+#ifdef WANT_ACCESSLIST
+    accesslist_cleanup();
+#endif
+  }
+  return NULL;
+}
+
+static pthread_t thread_id;
+void clean_init(void) { pthread_create(&thread_id, NULL, clean_worker, NULL); }
+
+void clean_deinit(void) {
+  pthread_mutex_lock(&g_clean_mutex);
+  pthread_cond_signal(&g_clean_wakeup);
+  pthread_mutex_unlock(&g_clean_mutex);
+  pthread_join(thread_id, NULL);
+}
diff --git a/src/ot_clean.h b/src/ot_clean.h
new file mode 100644
index 0000000..0592791
--- /dev/null
+++ b/src/ot_clean.h
@@ -0,0 +1,28 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_CLEAN_H__
+#define OT_CLEAN_H__
+
+#include "trackerlogic.h"
+
+/* The amount of time a clean cycle should take */
+#define OT_CLEAN_INTERVAL_MINUTES 2
+
+/* How often the cleaner may wake. A full sweep takes OT_CLEAN_INTERVAL_MINUTES.
+   The clean operations per wake is goverend by OT_BUCKET_COUNT_BITS,
+   set by the Makefile.
+   At the default of 1024 buckets this works out at one bucket every
+   117 ms. */
+#define OT_CLEAN_MAX_WAKES_PER_SECOND 10
+
+#define OT_CLEAN_WAKE_BUDGET      ((OT_CLEAN_INTERVAL_MINUTES) * 60 * (OT_CLEAN_MAX_WAKES_PER_SECOND))
+#define OT_CLEAN_BUCKETS_PER_WAKE (((OT_BUCKET_COUNT) + (OT_CLEAN_WAKE_BUDGET) - 1) / (OT_CLEAN_WAKE_BUDGET))
+#define OT_CLEAN_WAKES            ((OT_BUCKET_COUNT) / (OT_CLEAN_BUCKETS_PER_WAKE))
+#define OT_CLEAN_SLEEP            (((OT_CLEAN_INTERVAL_MINUTES) * 60 * 1000000) / (OT_CLEAN_WAKES))
+
+void clean_init(void);
+void clean_deinit(void);
+int  clean_single_torrent(ot_torrent *torrent);
+
+#endif
diff --git a/src/ot_config.c b/src/ot_config.c
new file mode 100644
index 0000000..95136b5
--- /dev/null
+++ b/src/ot_config.c
@@ -0,0 +1,586 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_event.h"
+#include "ot_config.h"
+#include "ot_http.h"
+#include "ot_ip.h"
+#include "ot_livesync.h"
+#include "ot_scan.h"
+#include "ot_stats.h"
+#include "trackerlogic.h"
+
+const char   *g_redirecturl;
+const char   *g_serverdir;
+const char   *g_serveruser;
+const char   *g_statefile;
+
+#define OT_LISTEN_INHERIT (-1)
+
+static ot_listen *g_listen;
+static size_t     g_listen_count;
+static int        g_listen_shared;
+static int        g_listen_workers_udp = 1;
+static int        g_listen_workers_tcp = 0;
+
+static void panic(const char *routine) __attribute__((noreturn));
+static void panic(const char *routine) {
+  fprintf(stderr, "%s: %s\n", routine, strerror(errno));
+  exit(111);
+}
+
+static void listen_append(const ot_ip6 ip, uint16_t port, PROTO_FLAG proto, int shared, int workers) {
+  ot_listen *grown = realloc(g_listen, (g_listen_count + 1) * sizeof(ot_listen));
+  ot_listen *entry;
+
+  if (!grown)
+    panic("listen_append");
+  g_listen = grown;
+
+  entry = g_listen + g_listen_count++;
+  memcpy(entry->ip, ip, sizeof(ot_ip6));
+  entry->port      = port;
+  entry->proto     = proto;
+  entry->shared  = shared;
+  entry->workers = workers;
+  entry->sock      = -1;
+}
+
+typedef enum { LISTEN_OPTION_UNKNOWN, LISTEN_OPTION_SHARED, LISTEN_OPTION_WORKERS } listen_option_kind;
+
+typedef struct {
+  const char        *name;
+  size_t             len;
+  listen_option_kind kind;
+  int                takes_value;
+} listen_option_key;
+
+#define LISTEN_OPTION_KEY(s, k, v) {s, sizeof(s) - 1, k, v}
+
+static const listen_option_key listen_option_keys[] = {
+    LISTEN_OPTION_KEY("shared",  LISTEN_OPTION_SHARED,  0),
+    LISTEN_OPTION_KEY("workers", LISTEN_OPTION_WORKERS, 1),
+};
+static const size_t listen_option_count = sizeof(listen_option_keys) / sizeof(listen_option_keys[0]);
+
+static listen_option_kind parse_listen_option(char **p) {
+  size_t i;
+
+  for (i = 0; i < listen_option_count; ++i) {
+    const listen_option_key *key = &listen_option_keys[i];
+    char                     delimiter = (*p)[key->len];
+
+    if (strncmp(*p, key->name, key->len))
+      continue;
+    if (key->takes_value ? delimiter != '=' : (delimiter && !isspace((unsigned char)delimiter)))
+      continue;
+
+    *p += key->len + (key->takes_value ? 1 : 0);
+    return key->kind;
+  }
+  return LISTEN_OPTION_UNKNOWN;
+}
+
+/* Options trailing an address in a listen statement, in any order */
+static int listen_scan_options(char *p, int *shared, int *workers) {
+  uint64_t value;
+
+  for (;;) {
+    while (isspace((unsigned char)*p))
+      ++p;
+    if (!*p)
+      return 1;
+
+    switch (parse_listen_option(&p)) {
+    case LISTEN_OPTION_SHARED:
+      *shared = 1;
+      break;
+    case LISTEN_OPTION_WORKERS: {
+      size_t off = scan_uint(p, &value, UINT_MAX);
+
+      if (!off)
+        return 0;
+      *workers  = (int)value;
+      p        += off;
+      break;
+    }
+    default:
+      return 0;
+    }
+  }
+}
+
+
+static const char *set_config_option(const char **option, char *value) {
+#ifdef _DEBUG
+  fprintf(stderr, "Setting config option: %s\n", value);
+#endif
+  while (isspace(*value))
+    ++value;
+  free((char *)*option);
+  return *option = strdup(value);
+}
+
+static int scan_ip6_port(const char *src, ot_ip6 ip, uint16_t *port) {
+  const char *s = src;
+  uint64_t    value;
+  int         off, bracket = 0;
+  while (isspace(*s))
+    ++s;
+  if (*s == '[')
+    ++s, ++bracket; /* for v6 style notation */
+  if (!(off = ip_parse(s, ip)))
+    return 0;
+  s += off;
+  if (bracket && *s == ']')
+    ++s;
+  if (*s == 0 || isspace(*s))
+    return s - src;
+  if (!ip_is_v4mapped(ip)) {
+    if (*s != ':' && *s != '.')
+      return 0;
+    if (!bracket && *(s) == ':')
+      return 0;
+    s++;
+  } else {
+    if (*(s++) != ':')
+      return 0;
+  }
+  if (!(off = scan_uint(s, &value, 65535)))
+    return 0;
+  *port = (uint16_t)value;
+  return off + s - src;
+}
+
+static int scan_ip6_net(const char *src, ot_net *net) {
+  const char *s = src;
+  uint64_t    value;
+  int         off;
+  while (isspace(*s))
+    ++s;
+  if (!(off = ip_parse(s, net->address)))
+    return 0;
+  s += off;
+  if (*s != '/')
+    net->bits = 128;
+  else {
+    s++;
+    if (!(off = scan_uint(s, &value, 128)))
+      return 0;
+    net->bits = (int)value;
+    if (ip_is_v4mapped(net->address))
+      net->bits += 96;
+    if (net->bits > 128)
+      return 0;
+    s += off;
+  }
+  return off + s - src;
+}
+
+typedef enum {
+    CONFIG_UNKNOWN,
+    CONFIG_TRACKER_ROOTDIR,
+    CONFIG_TRACKER_USER,
+    CONFIG_LISTEN_TCP_UDP,
+    CONFIG_LISTEN_TCP,
+    CONFIG_LISTEN_UDP,
+    CONFIG_LISTEN_UDP_WORKERS,
+    CONFIG_LISTEN_TCP_WORKERS,
+    CONFIG_LISTEN_SHARED,
+    CONFIG_ACCESS_WHITELIST,
+    CONFIG_ACCESS_BLACKLIST,
+    CONFIG_ACCESS_FIFO_ADD,
+    CONFIG_ACCESS_FIFO_DELETE,
+    CONFIG_ACCESS_STATS,
+    CONFIG_ACCESS_STATS_PATH,
+    CONFIG_ACCESS_PROXY,
+    CONFIG_TRACKER_REDIRECT_URL,
+    CONFIG_LIVESYNC_CLUSTER_NODE_IP,
+    CONFIG_LIVESYNC_CLUSTER_LISTEN,
+} config_kind;
+
+typedef struct {
+    const char *name;
+    size_t len;
+    config_kind kind;
+} config_key;
+
+#define CONFIG_KEY(s, k) { s, sizeof(s) - 1, k }
+
+static const config_key config_keys[] = {
+    CONFIG_KEY("tracker.rootdir",          CONFIG_TRACKER_ROOTDIR),
+    CONFIG_KEY("tracker.user",             CONFIG_TRACKER_USER),
+    CONFIG_KEY("listen.tcp_udp",           CONFIG_LISTEN_TCP_UDP),
+    CONFIG_KEY("listen.tcp",               CONFIG_LISTEN_TCP),
+    CONFIG_KEY("listen.udp",               CONFIG_LISTEN_UDP),
+    CONFIG_KEY("listen.udp.workers",       CONFIG_LISTEN_UDP_WORKERS),
+    CONFIG_KEY("listen.tcp.workers",       CONFIG_LISTEN_TCP_WORKERS),
+    CONFIG_KEY("listen.shared",            CONFIG_LISTEN_SHARED),
+#ifdef WANT_ACCESSLIST_WHITE
+    CONFIG_KEY("access.whitelist",         CONFIG_ACCESS_WHITELIST),
+#elif defined(WANT_ACCESSLIST_BLACK)
+    CONFIG_KEY("access.blacklist",         CONFIG_ACCESS_BLACKLIST),
+#endif
+#ifdef WANT_DYNAMIC_ACCESSLIST
+    CONFIG_KEY("access.fifo_add",          CONFIG_ACCESS_FIFO_ADD),
+    CONFIG_KEY("access.fifo_delete",       CONFIG_ACCESS_FIFO_DELETE),
+#endif
+#ifdef WANT_RESTRICT_STATS
+    CONFIG_KEY("access.stats",             CONFIG_ACCESS_STATS),
+#endif
+    CONFIG_KEY("access.stats_path",        CONFIG_ACCESS_STATS_PATH),
+#ifdef WANT_IP_FROM_PROXY
+    CONFIG_KEY("access.proxy",             CONFIG_ACCESS_PROXY),
+#endif
+    CONFIG_KEY("tracker.redirect_url",     CONFIG_TRACKER_REDIRECT_URL),
+#ifdef WANT_SYNC_LIVE
+    CONFIG_KEY("livesync.cluster.node_ip", CONFIG_LIVESYNC_CLUSTER_NODE_IP),
+    CONFIG_KEY("livesync.cluster.listen",  CONFIG_LIVESYNC_CLUSTER_LISTEN),
+#endif
+};
+static const size_t config_entry_count = sizeof(config_keys) / sizeof(config_keys[0]);
+
+static config_kind parse_config_key(char **p) {
+    size_t i;
+    for (i = 0; i < config_entry_count; ++i) {
+        const config_key *key = &config_keys[i];
+        if (strncmp(*p, key->name, key->len) == 0 && isspace((unsigned char)(*p)[key->len])) {
+            *p += key->len + 1;
+            /* Skip white spaces */
+            while (isspace((unsigned char)**p))
+              ++(*p);
+            return key->kind;
+        }
+    }
+    return CONFIG_UNKNOWN;
+}
+
+static int parse_configfile(char *config_filename) {
+  FILE  *config_file_handle;
+  char   inbuf[512];
+  ot_ip6 tmpip;
+#if defined(WANT_RESTRICT_STATS) || defined(WANT_IP_FROM_PROXY) || defined(WANT_SYNC_LIVE)
+  ot_net tmpnet;
+#endif
+  int bound = 0;
+
+  config_file_handle = fopen(config_filename, "r");
+
+  if (config_file_handle == NULL) {
+    fprintf(stderr, "Warning: Can't open config file: %s.", config_filename);
+    return 0;
+  }
+
+  while (fgets(inbuf, sizeof(inbuf), config_file_handle)) {
+    char       *p = inbuf, *end;
+    uint64_t    value;
+    uint16_t    tmpport = 6969;
+    config_kind kind;
+
+    /* Skip white spaces */
+    while (isspace((unsigned char)*p))
+      ++p;
+
+    /* Ignore comments and empty lines */
+    if ((*p == '#') || (*p == '\n') || (*p == 0))
+      continue;
+
+    /* consume trailing new lines and spaces */
+    end = p + strlen(p);
+    while (end > p && isspace((unsigned char)end[-1]))
+      *--end = 0;
+
+    /* Scan for commands */
+    kind = parse_config_key(&p);
+    switch (kind) {
+      case CONFIG_TRACKER_ROOTDIR:
+        set_config_option(&g_serverdir, p);
+        break;
+      case CONFIG_TRACKER_USER:
+        set_config_option(&g_serveruser, p);
+        break;
+      case CONFIG_LISTEN_TCP_UDP:
+      case CONFIG_LISTEN_TCP:
+      case CONFIG_LISTEN_UDP: {
+        int shared  = OT_LISTEN_INHERIT;
+        int workers = OT_LISTEN_INHERIT;
+        int off     = scan_ip6_port(p, tmpip, &tmpport);
+
+        if (!off || !listen_scan_options(p + off, &shared, &workers))
+          goto parse_error;
+        if (kind != CONFIG_LISTEN_UDP)
+          listen_append(tmpip, tmpport, FLAG_TCP, shared, workers), ++bound;
+        if (kind != CONFIG_LISTEN_TCP)
+          listen_append(tmpip, tmpport, FLAG_UDP, shared, workers), ++bound;
+        break;
+      }
+      case CONFIG_LISTEN_UDP_WORKERS:
+        if (!scan_uint(p, &value, UINT_MAX))
+          goto parse_error;
+        g_listen_workers_udp = (int)value;
+        break;
+      case CONFIG_LISTEN_TCP_WORKERS:
+        if (!scan_uint(p, &value, UINT_MAX))
+          goto parse_error;
+        g_listen_workers_tcp = (int)value;
+        break;
+      case CONFIG_LISTEN_SHARED:
+        if (!scan_uint(p, &value, 1))
+          goto parse_error;
+        g_listen_shared = (int)value;
+        break;
+#ifdef WANT_ACCESSLIST_WHITE
+      case CONFIG_ACCESS_WHITELIST:
+        set_config_option(&g_accesslist_filename, p);
+        break;
+#elif defined(WANT_ACCESSLIST_BLACK)
+      case CONFIG_ACCESS_BLACKLIST:
+        set_config_option(&g_accesslist_filename, p);
+        break;
+#endif
+#ifdef WANT_DYNAMIC_ACCESSLIST
+      case CONFIG_ACCESS_FIFO_ADD:
+        set_config_option(&g_accesslist_pipe_add, p);
+        break;
+      case CONFIG_ACCESS_FIFO_DELETE:
+        set_config_option(&g_accesslist_pipe_delete, p);
+        break;
+#endif
+#ifdef WANT_RESTRICT_STATS
+      case CONFIG_ACCESS_STATS:
+        if (!scan_ip6_net(p, &tmpnet))
+          goto parse_error;
+        accesslist_bless_net(&tmpnet, OT_PERMISSION_MAY_STAT);
+        break;
+#endif
+      case CONFIG_ACCESS_STATS_PATH:
+        set_config_option(&g_stats_path, p);
+        break;
+#ifdef WANT_IP_FROM_PROXY
+      case CONFIG_ACCESS_PROXY:
+        if (!scan_ip6_net(p, &tmpnet))
+          goto parse_error;
+        accesslist_bless_net(&tmpnet, OT_PERMISSION_MAY_PROXY);
+        break;
+#endif
+      case CONFIG_TRACKER_REDIRECT_URL:
+        set_config_option(&g_redirecturl, p);
+        break;
+#ifdef WANT_SYNC_LIVE
+      case CONFIG_LIVESYNC_CLUSTER_NODE_IP:
+        if (!scan_ip6_net(p, &tmpnet))
+          goto parse_error;
+        accesslist_bless_net(&tmpnet, OT_PERMISSION_MAY_LIVESYNC);
+        break;
+      case CONFIG_LIVESYNC_CLUSTER_LISTEN:
+        tmpport = LIVESYNC_PORT;
+        {
+          int shared = OT_LISTEN_INHERIT, dummy = OT_LISTEN_INHERIT;
+          int off       = scan_ip6_port(p, tmpip, &tmpport);
+
+          if (!off || !listen_scan_options(p + off, &shared, &dummy))
+            goto parse_error;
+          listen_append(tmpip, tmpport, FLAG_MCA, shared, OT_LISTEN_INHERIT);
+        }
+      break;
+#endif
+      default:
+        fprintf(stderr, "Unhandled line in config file: %s\n", inbuf);
+        break;
+      parse_error:
+        fprintf(stderr, "Parse error in config file: %s\n", inbuf);
+    }
+  }
+  fclose(config_file_handle);
+  return bound;
+}
+
+static void usage(char *name) {
+  fprintf(stderr,
+          "Usage: %s [-i ip] [-p port] [-P port] [-r redirect] [-d dir] [-u user] [-A ip[/bits]] [-f config] [-s livesyncport]"
+#ifdef WANT_ACCESSLIST_BLACK
+          " [-b blacklistfile]"
+#elif defined(WANT_ACCESSLIST_WHITE)
+          " [-w whitelistfile]"
+#endif
+          "\n",
+          name);
+}
+
+#define HELPLINE(opt, desc) fprintf(stderr, "\t%-10s%s\n", opt, desc)
+static void help(char *name) {
+  usage(name);
+
+  HELPLINE("-f config", "include and execute the config file");
+  HELPLINE("-i ip", "specify ip to bind to with next -[pP] (default: any, overrides preceeding ones)");
+  HELPLINE("-p port", "do bind to tcp port (default: 6969, you may specify more than one)");
+  HELPLINE("-P port", "do bind to udp port (default: 6969, you may specify more than one)");
+  HELPLINE("-r redirecturl", "specify url where / should be redirected to (default none)");
+  HELPLINE("-d dir", "specify directory to try to chroot to (default: \".\")");
+  HELPLINE("-u user", "specify user under whose privileges opentracker should run (default: \"nobody\")");
+  HELPLINE("-A ip[/bits]", "bless an ip address or net as admin address (e.g. to allow syncs from this address)");
+  HELPLINE("-v", "report version, event mechanism and the feature flags opentracker was built with");
+#ifdef WANT_ACCESSLIST_BLACK
+  HELPLINE("-b file", "specify blacklist file.");
+#elif defined(WANT_ACCESSLIST_WHITE)
+  HELPLINE("-w file", "specify whitelist file.");
+#endif
+
+  fprintf(stderr, "\nExample:   ./opentracker -i 127.0.0.1 -p 6969 -P 6969 -f ./opentracker.conf -i 10.1.1.23 -p 2710 -p 80\n");
+  fprintf(stderr, "           Here -i 127.0.0.1 selects the ip address for the next -p 6969 and -P 6969.\n");
+  fprintf(stderr, "           If no port is bound from config file or command line, the last address given\n");
+  fprintf(stderr, "           (or ::1 if none is set) will be used on port 6969.\n");
+}
+#undef HELPLINE
+
+
+static void listen_resolve_defaults(void) {
+  size_t i;
+
+  for (i = 0; i < g_listen_count; ++i) {
+    ot_listen *entry = g_listen + i;
+
+    if (entry->shared == OT_LISTEN_INHERIT)
+      entry->shared = g_listen_shared;
+    if (entry->workers == OT_LISTEN_INHERIT)
+      entry->workers = entry->proto == FLAG_TCP ? g_listen_workers_tcp : g_listen_workers_udp;
+
+    /* A tcp worker hands a connection it cannot finish to the event loop,
+       which only one thread may touch where the set is ours rather than the
+       kernel's */
+    if (entry->proto == FLAG_TCP && entry->workers > 1 && !event_can_share()) {
+      fprintf(stderr, "Warning: Multiple workers impossible on this platform with event mechanism %s chosen.\n",
+              event_mechanism());
+      entry->workers = 1;
+    }
+  }
+}
+
+ot_listen *config_listen_entries(size_t *count) {
+  *count = g_listen_count;
+  return g_listen;
+}
+
+void config_parse(int argc, char **argv) {
+  ot_ip6   serverip;
+  ot_net   tmpnet;
+  int      bound = 0, scanon = 1;
+  uint64_t value;
+
+  memset(serverip, 0, sizeof(ot_ip6));
+#ifdef WANT_V4_ONLY
+  serverip[10] = serverip[11] = -1;
+#endif
+
+  while (scanon) {
+    switch (getopt(argc, argv,
+                   ":i:p:A:P:d:u:r:s:f:l:v"
+#ifdef WANT_ACCESSLIST_BLACK
+                   "b:"
+#elif defined(WANT_ACCESSLIST_WHITE)
+                   "w:"
+#endif
+                   "h")) {
+    case -1:
+      scanon = 0;
+      break;
+    case 'i':
+      if (!ip_parse(optarg, serverip)) {
+        usage(argv[0]);
+        exit(1);
+      }
+      break;
+#ifdef WANT_ACCESSLIST_BLACK
+    case 'b':
+      set_config_option(&g_accesslist_filename, optarg);
+      break;
+#elif defined(WANT_ACCESSLIST_WHITE)
+    case 'w':
+      set_config_option(&g_accesslist_filename, optarg);
+      break;
+#endif
+    case 'p':
+      if (!scan_uint(optarg, &value, 65535)) {
+        usage(argv[0]);
+        exit(1);
+      }
+      listen_append(serverip, (uint16_t)value, FLAG_TCP, OT_LISTEN_INHERIT, OT_LISTEN_INHERIT);
+      bound++;
+      break;
+    case 'P':
+      if (!scan_uint(optarg, &value, 65535)) {
+        usage(argv[0]);
+        exit(1);
+      }
+      listen_append(serverip, (uint16_t)value, FLAG_UDP, OT_LISTEN_INHERIT, OT_LISTEN_INHERIT);
+      bound++;
+      break;
+#ifdef WANT_SYNC_LIVE
+    case 's':
+      if (!scan_uint(optarg, &value, 65535)) {
+        usage(argv[0]);
+        exit(1);
+      }
+      listen_append(serverip, (uint16_t)value, FLAG_MCA, OT_LISTEN_INHERIT, OT_LISTEN_INHERIT);
+      break;
+#endif
+    case 'd':
+      set_config_option(&g_serverdir, optarg);
+      break;
+    case 'u':
+      set_config_option(&g_serveruser, optarg);
+      break;
+    case 'r':
+      set_config_option(&g_redirecturl, optarg);
+      break;
+    case 'l':
+      g_statefile = optarg;
+      break;
+    case 'A':
+      if (!scan_ip6_net(optarg, &tmpnet)) {
+        usage(argv[0]);
+        exit(1);
+      }
+      accesslist_bless_net(&tmpnet, 0xffff); /* Allow everything for now */
+      break;
+    case 'f':
+      bound += parse_configfile(optarg);
+      break;
+    case 'h':
+      help(argv[0]);
+      exit(0);
+    case 'v': {
+      char  buffer[8192];
+      char *cursor = buffer;
+
+      stats_return_tracker_version(&cursor, buffer + sizeof(buffer) - 1);
+      stats_return_tracker_features(&cursor, buffer + sizeof(buffer) - 1);
+      *cursor = 0;
+      fputs(buffer, stderr);
+      exit(0);
+    }
+    default:
+    case '?':
+      usage(argv[0]);
+      exit(1);
+    }
+  }
+
+  if (!bound) {
+    listen_append(serverip, 6969, FLAG_TCP, OT_LISTEN_INHERIT, OT_LISTEN_INHERIT);
+    listen_append(serverip, 6969, FLAG_UDP, OT_LISTEN_INHERIT, OT_LISTEN_INHERIT);
+  }
+
+  listen_resolve_defaults();
+}
diff --git a/src/ot_config.h b/src/ot_config.h
new file mode 100644
index 0000000..79187ee
--- /dev/null
+++ b/src/ot_config.h
@@ -0,0 +1,33 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_CONFIG_H__
+#define OT_CONFIG_H__
+
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+/* An address opentracker was asked to listen on. Options the statement did
+   not name have been filled in from the file wide defaults by the time these
+   are handed out. sock is filled in by whoever binds them. */
+typedef struct {
+  ot_ip6     ip;
+  uint16_t   port;
+  PROTO_FLAG proto;
+  int        shared;
+  int        workers;
+  int64_t    sock;
+} ot_listen;
+
+extern const char *g_redirecturl;
+extern const char *g_serverdir;
+extern const char *g_serveruser;
+extern const char *g_statefile;
+
+/* Reads the command line and every config file it names. Exits on error. */
+void       config_parse(int argc, char **argv);
+
+ot_listen *config_listen_entries(size_t *count);
+
+#endif
diff --git a/src/ot_event.c b/src/ot_event.c
new file mode 100644
index 0000000..6062f70
--- /dev/null
+++ b/src/ot_event.c
@@ -0,0 +1,357 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_event.h"
+
+/* One caller waits, so the scratch the mechanism needs is kept here rather
+   than allocated per call. */
+
+/* poll works everywhere and is what the BSDs get until kqueue is written.
+   Defining OT_EVENT_FORCE_POLL picks it on a platform that would otherwise
+   use something better, which is how both are exercised by the tests. */
+#if defined(OT_EVENT_FORCE_POLL)
+#define OT_EVENT_POLL
+#elif defined(OT_EVENT_FORCE_KQUEUE)
+#define OT_EVENT_KQUEUE
+#elif defined(__linux__)
+#define OT_EVENT_EPOLL
+#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || defined(__APPLE__)
+#define OT_EVENT_KQUEUE
+#else
+#define OT_EVENT_POLL
+#endif
+
+#ifdef OT_EVENT_EPOLL
+/* ------------------------------------------------------------- epoll */
+
+#include <sys/epoll.h>
+
+static int                 g_epoll = -1;
+static struct epoll_event *g_ready;
+static int                 g_ready_space;
+
+const char *event_mechanism(void) { return "epoll"; }
+/* The set lives in the kernel, and epoll_ctl during another thread's
+   epoll_wait is what it is for */
+int         event_can_share(void) { return 1; }
+
+int event_init(void) {
+  g_ready       = NULL;
+  g_ready_space = 0;
+  return (g_epoll = epoll_create1(EPOLL_CLOEXEC)) == -1 ? -1 : 0;
+}
+
+void event_deinit(void) {
+  if (g_epoll != -1)
+    close(g_epoll);
+  free(g_ready);
+  g_epoll       = -1;
+  g_ready       = NULL;
+  g_ready_space = 0;
+}
+
+static int event_ctl(int op, int fd, int what, uint32_t generation) {
+  struct epoll_event ev;
+
+  memset(&ev, 0, sizeof(ev));
+  ev.events = (what & EVENT_IN ? (uint32_t)EPOLLIN : 0) | (what & EVENT_OUT ? (uint32_t)EPOLLOUT : 0);
+  /* The generation rides along inside the kernel, so an event says which
+     connection it belongs to without anybody looking it up */
+  ev.data.u64 = ((uint64_t)generation << 32) | (uint32_t)fd;
+  return epoll_ctl(g_epoll, op, fd, &ev);
+}
+
+int event_add(int fd, int what, uint32_t generation) { return event_ctl(EPOLL_CTL_ADD, fd, what, generation); }
+int event_modify(int fd, int what, uint32_t generation) { return event_ctl(EPOLL_CTL_MOD, fd, what, generation); }
+int event_del(int fd) { return epoll_ctl(g_epoll, EPOLL_CTL_DEL, fd, NULL); }
+
+/* A descriptor leaves the interest list when the last reference to its open
+   file description is closed, and the tracker never duplicates one */
+int event_close(int fd) { return close(fd); }
+
+int event_wait(ot_event *out, int max, int timeout_ms) {
+  int count, i;
+
+  if (max > g_ready_space) {
+    struct epoll_event *grown = realloc(g_ready, (size_t)max * sizeof(struct epoll_event));
+
+    if (!grown)
+      return -1;
+    g_ready       = grown;
+    g_ready_space = max;
+  }
+
+  /* An interrupted wait is reported as no events rather than retried here,
+     so that the caller gets to look at whatever the signal was about */
+  if ((count = epoll_wait(g_epoll, g_ready, max, timeout_ms)) == -1)
+    return errno == EINTR ? 0 : -1;
+  for (i = 0; i < count; ++i) {
+    uint32_t events = g_ready[i].events;
+
+    out[i].fd         = (int)(uint32_t)g_ready[i].data.u64;
+    out[i].generation = (uint32_t)(g_ready[i].data.u64 >> 32);
+    /* A hangup or an error is reported as both, so whichever side the caller
+       was waiting on gets to notice */
+    out[i].what = (events & (EPOLLIN | EPOLLHUP | EPOLLERR) ? EVENT_IN : 0) |
+                  (events & (EPOLLOUT | EPOLLHUP | EPOLLERR) ? EVENT_OUT : 0);
+  }
+  return count;
+}
+
+#endif /* OT_EVENT_EPOLL */
+
+#ifdef OT_EVENT_KQUEUE
+/* ------------------------------------------------------------ kqueue */
+
+#include <sys/event.h>
+#include <sys/time.h>
+#include <sys/types.h>
+
+static int            g_kqueue = -1;
+static struct kevent *g_ready;
+static int            g_ready_space;
+
+const char *event_mechanism(void) { return "kqueue"; }
+/* The set lives in the kernel, and kevent may be called from any thread */
+int         event_can_share(void) { return 1; }
+
+int event_init(void) {
+  g_ready       = NULL;
+  g_ready_space = 0;
+  return (g_kqueue = kqueue()) == -1 ? -1 : 0;
+}
+
+void event_deinit(void) {
+  if (g_kqueue != -1)
+    close(g_kqueue);
+  free(g_ready);
+  g_kqueue      = -1;
+  g_ready       = NULL;
+  g_ready_space = 0;
+}
+
+/* kqueue keeps one registration per filter, so reading and writing are two
+   entries. A change of interest is an add of the one wanted and a delete
+   of the one not. The generation travels in udata, which the kernel passes
+   back untouched. */
+static int event_change(int fd, int what, uint32_t generation, int deleting) {
+  struct kevent change[2], result[2];
+  void         *udata     = (void *)(uintptr_t)(((uint64_t)generation << 32) | (uint32_t)fd);
+  int           succeeded = 0, count, i;
+
+  EV_SET(&change[0], (uintptr_t)fd, EVFILT_READ,
+         EV_RECEIPT | ((deleting || !(what & EVENT_IN)) ? EV_DELETE : EV_ADD), 0, 0, udata);
+  EV_SET(&change[1], (uintptr_t)fd, EVFILT_WRITE,
+         EV_RECEIPT | ((deleting || !(what & EVENT_OUT)) ? EV_DELETE : EV_ADD), 0, 0, udata);
+
+  if ((count = kevent(g_kqueue, change, 2, result, 2, NULL)) == -1)
+    return -1;
+
+  for (i = 0; i < count && i < 2; ++i) {
+    if (!result[i].data) {
+      ++succeeded;
+      continue;
+    }
+    /* Dropping interest we never registered is not a failure */
+    if ((change[i].flags & EV_DELETE) && result[i].data == ENOENT)
+      continue;
+    errno = (int)result[i].data;
+    return -1;
+  }
+
+  /* Nothing at all was registered or removed, so the descriptor is unknown */
+  if (!succeeded) {
+    errno = ENOENT;
+    return -1;
+  }
+  return 0;
+}
+
+int event_add(int fd, int what, uint32_t generation) { return what ? event_change(fd, what, generation, 0) : 0; }
+int event_modify(int fd, int what, uint32_t generation) { return event_change(fd, what, generation, 0); }
+int event_del(int fd) { return event_change(fd, 0, 0, 1); }
+
+/* Closing a descriptor removes every kevent that references it */
+int event_close(int fd) { return close(fd); }
+
+int event_wait(ot_event *out, int max, int timeout_ms) {
+  struct timespec  timeout;
+  struct timespec *deadline = NULL;
+  int              count, i;
+
+  if (max > g_ready_space) {
+    struct kevent *grown = realloc(g_ready, (size_t)max * sizeof(struct kevent));
+
+    if (!grown)
+      return -1;
+    g_ready       = grown;
+    g_ready_space = max;
+  }
+
+  if (timeout_ms >= 0) {
+    timeout.tv_sec  = timeout_ms / 1000;
+    timeout.tv_nsec = (long)(timeout_ms % 1000) * 1000000;
+    deadline        = &timeout;
+  }
+
+  /* An interrupted wait is reported as no events rather than retried here,
+     so that the caller gets to look at whatever the signal was about */
+  if ((count = kevent(g_kqueue, NULL, 0, g_ready, max, deadline)) == -1)
+    return errno == EINTR ? 0 : -1;
+  for (i = 0; i < count; ++i) {
+    uint64_t udata = (uint64_t)(uintptr_t)g_ready[i].udata;
+    int      eof   = (g_ready[i].flags & (EV_EOF | EV_ERROR)) != 0;
+
+    out[i].fd         = (int)(uint32_t)udata;
+    out[i].generation = (uint32_t)(udata >> 32);
+    out[i].what       = ((g_ready[i].filter == EVFILT_READ || eof) ? EVENT_IN : 0) |
+                  ((g_ready[i].filter == EVFILT_WRITE || eof) ? EVENT_OUT : 0);
+  }
+  return count;
+}
+
+#endif /* OT_EVENT_KQUEUE */
+
+#ifdef OT_EVENT_POLL
+/* -------------------------------------------------------------- poll */
+
+#include <poll.h>
+
+/* poll wants its descriptors packed, so the registered ones live in one
+   array and a second maps a descriptor number to its place in it. */
+static struct pollfd *g_pfds;
+static uint32_t      *g_generation;
+static int           *g_where;
+static int            g_count, g_space, g_where_space;
+
+const char *event_mechanism(void) { return "poll"; }
+/* The arrays below are ours and nothing guards them */
+int         event_can_share(void) { return 0; }
+
+int event_init(void) {
+  g_pfds = NULL, g_generation = NULL, g_where = NULL;
+  g_count = g_space = g_where_space = 0;
+  return 0;
+}
+
+void event_deinit(void) {
+  free(g_pfds), free(g_generation), free(g_where);
+  g_pfds = NULL, g_generation = NULL, g_where = NULL;
+  g_count = g_space = g_where_space = 0;
+}
+
+static short event_to_poll(int what) {
+  return (short)((what & EVENT_IN ? POLLIN : 0) | (what & EVENT_OUT ? POLLOUT : 0));
+}
+
+static int event_room_for(int fd) {
+  if (fd >= g_where_space) {
+    int  space = g_where_space ? g_where_space : 64;
+    int *grown;
+
+    while (space <= fd)
+      space *= 2;
+    if (!(grown = realloc(g_where, (size_t)space * sizeof(int))))
+      return -1;
+    while (g_where_space < space)
+      grown[g_where_space++] = -1;
+    g_where = grown;
+  }
+
+  if (g_count == g_space) {
+    int            space = g_space ? g_space * 2 : 64;
+    struct pollfd *pfds  = realloc(g_pfds, (size_t)space * sizeof(struct pollfd));
+    uint32_t      *gens;
+
+    if (!pfds)
+      return -1;
+    g_pfds = pfds;
+    if (!(gens = realloc(g_generation, (size_t)space * sizeof(uint32_t))))
+      return -1;
+    g_generation = gens;
+    g_space      = space;
+  }
+  return 0;
+}
+
+int event_add(int fd, int what, uint32_t generation) {
+  if (fd < 0 || event_room_for(fd) == -1)
+    return -1;
+  if (g_where[fd] != -1) {
+    errno = EEXIST;
+    return -1;
+  }
+
+  g_pfds[g_count].fd      = fd;
+  g_pfds[g_count].events  = event_to_poll(what);
+  g_pfds[g_count].revents = 0;
+  g_generation[g_count]   = generation;
+  g_where[fd]             = g_count++;
+  return 0;
+}
+
+int event_modify(int fd, int what, uint32_t generation) {
+  if (fd < 0 || fd >= g_where_space || g_where[fd] == -1) {
+    errno = ENOENT;
+    return -1;
+  }
+  g_pfds[g_where[fd]].events = event_to_poll(what);
+  g_generation[g_where[fd]]  = generation;
+  return 0;
+}
+
+int event_del(int fd) {
+  int at;
+
+  if (fd < 0 || fd >= g_where_space || (at = g_where[fd]) == -1) {
+    errno = ENOENT;
+    return -1;
+  }
+
+  /* The last one moves into the gap, so the array stays packed */
+  g_pfds[at]            = g_pfds[--g_count];
+  g_generation[at]      = g_generation[g_count];
+  g_where[g_pfds[at].fd] = at;
+  g_where[fd]            = -1;
+  return 0;
+}
+
+/* Nothing here lives in the kernel, so the entry has to come out by hand
+   before the descriptor goes, or poll reports POLLNVAL for it forever */
+int event_close(int fd) {
+  event_del(fd);
+  return close(fd);
+}
+
+int event_wait(ot_event *out, int max, int timeout_ms) {
+  int ready, found = 0, i;
+
+  /* An interrupted wait is reported as no events rather than retried here,
+     so that the caller gets to look at whatever the signal was about */
+  if ((ready = poll(g_pfds, (nfds_t)g_count, timeout_ms)) == -1)
+    return errno == EINTR ? 0 : -1;
+  if (ready <= 0)
+    return ready;
+
+  for (i = 0; i < g_count && found < max; ++i) {
+    short revents = g_pfds[i].revents;
+
+    if (!revents)
+      continue;
+    out[found].fd         = g_pfds[i].fd;
+    out[found].generation = g_generation[i];
+    out[found].what       = (revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL) ? EVENT_IN : 0) |
+                      (revents & (POLLOUT | POLLHUP | POLLERR | POLLNVAL) ? EVENT_OUT : 0);
+    ++found;
+  }
+  return found;
+}
+
+#endif /* OT_EVENT_POLL */
diff --git a/src/ot_event.h b/src/ot_event.h
new file mode 100644
index 0000000..cb84ca8
--- /dev/null
+++ b/src/ot_event.h
@@ -0,0 +1,47 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_EVENT_H__
+#define OT_EVENT_H__
+
+#include <stdint.h>
+
+/* Which descriptors have become readable or writable, asked of whichever
+   mechanism the kernel offers. The generation a descriptor was registered
+   with is handed back with every event, so a caller can tell an event for
+   the connection it is holding from one for a connection that has since been
+   closed and had its number reused. */
+
+enum { EVENT_IN = 1, EVENT_OUT = 2 };
+
+typedef struct {
+  int      fd;
+  uint32_t generation;
+  int      what;
+} ot_event;
+
+int  event_init(void);
+void event_deinit(void);
+
+int  event_add(int fd, int what, uint32_t generation);
+int  event_modify(int fd, int what, uint32_t generation);
+int  event_del(int fd);
+
+/* Stop watching a descriptor and close it. Where the kernel drops a closed
+   descriptor from its set by itself, this is one system call where doing the
+   two separately would be two. */
+int  event_close(int fd);
+
+/* Waits at most timeout_ms, or indefinitely when that is negative, and fills
+   out with up to max ready descriptors. Returns how many, or -1. */
+int  event_wait(ot_event *out, int max, int timeout_ms);
+
+/* Whether the registered set may be changed from another thread while this
+   one is waiting on it. True where the kernel keeps the set, false where
+   this module keeps it in memory of its own. */
+int  event_can_share(void);
+
+/* Which mechanism was compiled in, for the version string */
+const char *event_mechanism(void);
+
+#endif
diff --git a/src/ot_fdstate.c b/src/ot_fdstate.c
new file mode 100644
index 0000000..8e4bd89
--- /dev/null
+++ b/src/ot_fdstate.c
@@ -0,0 +1,202 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdatomic.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/types.h>
+
+/* Opentracker */
+#include "ot_fdstate.h"
+
+enum { FD_FREE, FD_IDLE, FD_BUSY, FD_CLOSING };
+
+/* Generation and state share one word so that taking the state is also a
+   check that the generation has not moved */
+#define FD_GEN(w)       ((uint32_t)((w) >> 32))
+#define FD_ST(w)        ((uint32_t)(((w) >> 24) & 0xff))
+#define FD_WORD(g, s)   (((uint64_t)(g) << 32) | ((uint64_t)(s) << 24))
+#define FD_SET_ST(w, s) (((w) & ~(uint64_t)0xff000000) | ((uint64_t)(s) << 24))
+
+typedef struct {
+  _Atomic uint64_t state;
+  _Atomic(void *)  cookie;
+  _Atomic ot_time  expiry;
+} ot_fdslot;
+
+/* A descriptor the kernel can hand out is below the limit it was handed out
+   under, but the limit can be raised after we sized the table, so an out of
+   range descriptor is rejected */
+#define FD_SLOTS_MAX (1u << 20)
+
+static ot_fdslot      *g_slots;
+static size_t          g_slot_count;
+/* Descriptors are handed out lowest first, so a sweep only has to walk as
+   far as the highest one ever seen rather than the whole table. */
+static _Atomic size_t  g_slot_highest;
+
+int fdstate_init(void) {
+  struct rlimit limit;
+  size_t        count = FD_SLOTS_MAX;
+
+  if (getrlimit(RLIMIT_NOFILE, &limit) == 0 && limit.rlim_cur != RLIM_INFINITY && limit.rlim_cur < FD_SLOTS_MAX)
+    count = (size_t)limit.rlim_cur;
+
+  g_slots = mmap(NULL, count * sizeof(ot_fdslot), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (g_slots == MAP_FAILED) {
+    g_slots = NULL;
+    return -1;
+  }
+
+  g_slot_count = count;
+  atomic_store(&g_slot_highest, 0);
+  return 0;
+}
+
+void fdstate_deinit(void) {
+  if (g_slots)
+    munmap(g_slots, g_slot_count * sizeof(ot_fdslot));
+  g_slots      = NULL;
+  g_slot_count = 0;
+  atomic_store(&g_slot_highest, 0);
+}
+
+size_t fdstate_slots(void) { return g_slot_count; }
+
+static ot_fdslot *fdstate_slot(int fd) {
+  if (fd < 0 || (size_t)fd >= g_slot_count)
+    return NULL;
+  return g_slots + fd;
+}
+
+uint32_t fdstate_open(int fd, void *cookie, ot_time expiry) {
+  ot_fdslot *slot = fdstate_slot(fd);
+  uint64_t   word;
+
+  if (!slot)
+    return 0;
+
+  {
+    size_t highest = atomic_load_explicit(&g_slot_highest, memory_order_relaxed);
+
+    while ((size_t)fd > highest &&
+           !atomic_compare_exchange_weak_explicit(&g_slot_highest, &highest, (size_t)fd, memory_order_relaxed,
+                                                  memory_order_relaxed))
+      ;
+  }
+
+  word = atomic_load_explicit(&slot->state, memory_order_relaxed);
+  atomic_store_explicit(&slot->cookie, cookie, memory_order_release);
+  atomic_store_explicit(&slot->expiry, expiry, memory_order_relaxed);
+  /* Publishes the two above to whoever claims the slot next */
+  atomic_store_explicit(&slot->state, FD_WORD(FD_GEN(word), FD_IDLE), memory_order_release);
+
+  return FD_GEN(word);
+}
+
+uint32_t fdstate_generation(int fd) {
+  ot_fdslot *slot = fdstate_slot(fd);
+
+  return slot ? FD_GEN(atomic_load_explicit(&slot->state, memory_order_relaxed)) : 0;
+}
+
+int fdstate_claim(int fd, uint32_t generation) {
+  ot_fdslot *slot = fdstate_slot(fd);
+  uint64_t   word;
+
+  if (!slot)
+    return 0;
+
+  word = atomic_load_explicit(&slot->state, memory_order_acquire);
+  for (;;) {
+    if (FD_GEN(word) != generation || FD_ST(word) != FD_IDLE)
+      return 0;
+    if (atomic_compare_exchange_weak_explicit(&slot->state, &word, FD_SET_ST(word, FD_BUSY), memory_order_acquire,
+                                              memory_order_relaxed))
+      return 1;
+    /* word now holds what was really there, so the test above runs again */
+  }
+}
+
+void fdstate_release(int fd) {
+  ot_fdslot *slot = fdstate_slot(fd);
+  uint64_t   word;
+
+  if (!slot)
+    return;
+
+  word = atomic_load_explicit(&slot->state, memory_order_relaxed);
+  atomic_store_explicit(&slot->state, FD_SET_ST(word, FD_IDLE), memory_order_release);
+}
+
+int fdstate_claim_expired(int fd, ot_time now) {
+  ot_fdslot *slot = fdstate_slot(fd);
+  uint64_t   word;
+  ot_time    expiry;
+
+  if (!slot)
+    return 0;
+
+  /* Reading before asking for the slot keeps the common case, a descriptor
+     that has not expired, off the bus entirely */
+  word = atomic_load_explicit(&slot->state, memory_order_relaxed);
+  if (FD_ST(word) != FD_IDLE)
+    return 0;
+  expiry = atomic_load_explicit(&slot->expiry, memory_order_relaxed);
+  if (!expiry || expiry > now)
+    return 0;
+
+  /* Nothing can move the expiry while the slot sits at FD_IDLE, so winning
+     the slot is the last word */
+  return atomic_compare_exchange_strong_explicit(&slot->state, &word, FD_SET_ST(word, FD_CLOSING), memory_order_acquire,
+                                                 memory_order_relaxed);
+}
+
+void fdstate_close(int fd) {
+  ot_fdslot *slot = fdstate_slot(fd);
+  uint64_t   word;
+
+  if (!slot)
+    return;
+
+  word = atomic_load_explicit(&slot->state, memory_order_relaxed);
+  atomic_store_explicit(&slot->cookie, NULL, memory_order_relaxed);
+  atomic_store_explicit(&slot->expiry, 0, memory_order_relaxed);
+  atomic_store_explicit(&slot->state, FD_WORD(FD_GEN(word) + 1, FD_FREE), memory_order_release);
+}
+
+int fdstate_next_expired(ot_time now, int *cursor) {
+  size_t highest = atomic_load_explicit(&g_slot_highest, memory_order_relaxed);
+
+  for (; (size_t)*cursor <= highest; ++*cursor)
+    if (fdstate_claim_expired(*cursor, now))
+      return (*cursor)++;
+
+  return -1;
+}
+
+void *fdstate_cookie(int fd) {
+  ot_fdslot *slot = fdstate_slot(fd);
+
+  /* Pairs with the release in fdstate_set_cookie and fdstate_open */
+  return slot ? atomic_load_explicit(&slot->cookie, memory_order_acquire) : NULL;
+}
+
+void fdstate_set_cookie(int fd, void *cookie) {
+  ot_fdslot *slot = fdstate_slot(fd);
+
+  /* Publishes what the cookie points at to whoever reads it next, which may
+     be another thread entirely */
+  if (slot)
+    atomic_store_explicit(&slot->cookie, cookie, memory_order_release);
+}
+
+void fdstate_set_expiry(int fd, ot_time expiry) {
+  ot_fdslot *slot = fdstate_slot(fd);
+
+  if (slot)
+    atomic_store_explicit(&slot->expiry, expiry, memory_order_relaxed);
+}
diff --git a/src/ot_fdstate.h b/src/ot_fdstate.h
new file mode 100644
index 0000000..60fe070
--- /dev/null
+++ b/src/ot_fdstate.h
@@ -0,0 +1,62 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_FDSTATE_H__
+#define OT_FDSTATE_H__
+
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+/* What the tracker knows about a file descriptor: who owns it, when it
+   should be given up on, and whether anyone is working on it right now.
+
+   A descriptor number says nothing about identity, since the kernel hands
+   the same number out again as soon as it is closed. Every slot therefore
+   carries a generation that is bumped when the descriptor is given up, and
+   every caller that was told about a descriptor has to say which generation
+   it was told about. A caller holding a stale generation is turned away
+   instead of being handed somebody else's connection.
+
+   The table is sized once from RLIMIT_NOFILE and never moves, so looking a
+   descriptor up needs no synchronisation at all. */
+
+int      fdstate_init(void);
+void     fdstate_deinit(void);
+size_t   fdstate_slots(void);
+
+/* Take a freshly accepted descriptor into the table and return the
+   generation to quote when asking for it back. expiry of 0 never expires. */
+uint32_t fdstate_open(int fd, void *cookie, ot_time expiry);
+
+/* Which generation a descriptor currently carries, to check an event that
+   was handed out earlier against the connection living there now. */
+uint32_t fdstate_generation(int fd);
+
+/* Ask for exclusive use. Returns 0 if the descriptor has been recycled since
+   generation was handed out, or if somebody else is using it. */
+int      fdstate_claim(int fd, uint32_t generation);
+void     fdstate_release(int fd);
+
+/* The cleaner's side of the same thing: takes the descriptor only if nobody
+   is working on it and it really has expired. Never waits. */
+int      fdstate_claim_expired(int fd, ot_time now);
+
+/* Give the descriptor up. The generation is bumped here, which has to happen
+   before close(2) so that the kernel cannot reissue the number while events
+   quoting the old generation are still in flight. */
+void     fdstate_close(int fd);
+
+/* Walks the table for descriptors that have expired, handing back one at a
+   time until it returns -1. The cursor belongs to the caller, so several
+   sweepers can run without sharing anything. */
+int      fdstate_next_expired(ot_time now, int *cursor);
+
+/* Both only valid while the caller holds the descriptor. */
+void    *fdstate_cookie(int fd);
+
+/* Hand the slot a different cookie, for a connection whose state has moved */
+void     fdstate_set_cookie(int fd, void *cookie);
+void     fdstate_set_expiry(int fd, ot_time expiry);
+
+#endif
diff --git a/src/ot_fmt.c b/src/ot_fmt.c
new file mode 100644
index 0000000..362c9b5
--- /dev/null
+++ b/src/ot_fmt.c
@@ -0,0 +1,40 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+/* Opentracker */
+#include "ot_fmt.h"
+
+void fmt_append(char **cursor, const char *end, const char *format, ...) {
+  va_list arguments;
+  size_t  room;
+  int     written;
+
+  if (*cursor >= end) {
+    *cursor = (char *)end;
+    return;
+  }
+
+  room = (size_t)(end - *cursor);
+  va_start(arguments, format);
+  written = vsnprintf(*cursor, room, format, arguments);
+  va_end(arguments);
+
+  if (written < 0)
+    return;
+  *cursor = (size_t)written >= room ? (char *)end : *cursor + written;
+}
+
+void fmt_bytes(char **cursor, const char *end, const void *bytes, size_t length) {
+  if (*cursor >= end || (size_t)(end - *cursor) < length) {
+    *cursor = (char *)end;
+    return;
+  }
+
+  memcpy(*cursor, bytes, length);
+  *cursor += length;
+}
diff --git a/src/ot_fmt.h b/src/ot_fmt.h
new file mode 100644
index 0000000..214cbc4
--- /dev/null
+++ b/src/ot_fmt.h
@@ -0,0 +1,19 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_FMT_H__
+#define OT_FMT_H__
+
+#include <stddef.h>
+
+/* Appending to a cursor that walks a fixed buffer. Both take the cursor by
+   reference and advance it, so a reply is written as a run of statements and
+   no caller does pointer arithmetic of its own. */
+
+void fmt_append(char **cursor, const char *end, const char *format, ...) __attribute__((format(printf, 3, 4)));
+
+/* Append raw bytes for the binary stretches of a bencoded reply.
+   Either everything is appended or nothing at all */
+void fmt_bytes(char **cursor, const char *end, const void *bytes, size_t length);
+
+#endif
diff --git a/src/ot_fullscrape.c b/src/ot_fullscrape.c
new file mode 100644
index 0000000..9afad92
--- /dev/null
+++ b/src/ot_fullscrape.c
@@ -0,0 +1,455 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifdef WANT_FULLSCRAPE
+
+/* System */
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <string.h>
+#ifdef WANT_COMPRESSION_GZIP
+#include <zlib.h>
+#endif
+#ifdef WANT_COMPRESSION_ZSTD
+#include <zstd.h>
+#endif
+
+/* Opentracker */
+#include "ot_fmt.h"
+#include "ot_hex.h"
+#include "ot_fullscrape.h"
+#include "ot_iovec.h"
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+#include "ot_urlencoded.h"
+#include "trackerlogic.h"
+
+/* Fetch full scrape info for all torrents
+   Full scrapes usually are huge and one does not want to
+   allocate more memory. So lets get them in 512k units
+*/
+#define OT_SCRAPE_CHUNK_SIZE  (1024 * 1024)
+
+/* "d8:completei%zde10:downloadedi%zde10:incompletei%zdee" */
+#define OT_SCRAPE_MAXENTRYLEN 256
+
+/* Forward declaration */
+static void fullscrape_make(int taskid, ot_tasktype mode);
+#ifdef WANT_COMPRESSION_GZIP
+static void fullscrape_make_gzip(int taskid, ot_tasktype mode);
+#endif
+#ifdef WANT_COMPRESSION_ZSTD
+static void fullscrape_make_zstd(int taskid, ot_tasktype mode);
+#endif
+
+/* Converter function from memory to human readable hex strings
+   XXX - Duplicated from ot_stats. Needs fix. */
+/* This is the entry point into this worker thread
+   It grabs tasks from mutex_tasklist and delivers results back
+*/
+static void *fullscrape_worker(void *args) {
+  (void)args;
+
+  while (g_opentracker_running) {
+    ot_tasktype tasktype = TASK_FULLSCRAPE;
+    ot_taskid   taskid   = workqueue_poptask(&tasktype);
+    if (!taskid)
+      break;
+#ifdef WANT_COMPRESSION_ZSTD
+    if (tasktype & TASK_FLAG_ZSTD)
+      fullscrape_make_zstd(taskid, tasktype);
+    else
+#endif
+#ifdef WANT_COMPRESSION_GZIP
+    if (tasktype & TASK_FLAG_GZIP)
+      fullscrape_make_gzip(taskid, tasktype);
+    else
+#endif
+      fullscrape_make(taskid, tasktype);
+    workqueue_pushchunked(taskid, NULL);
+  }
+  return NULL;
+}
+
+static pthread_t thread_id;
+void fullscrape_init(void) {
+  pthread_create( &thread_id, NULL, fullscrape_worker, NULL );
+}
+
+void fullscrape_deinit(void) {
+  workqueue_wakeall();
+  pthread_join( thread_id, NULL );
+}
+
+void fullscrape_deliver( int64_t sock, ot_tasktype tasktype ) {
+  workqueue_pushtask( sock, TASK_FULLSCRAPE | tasktype );
+}
+
+static void fullscrape_write_one( ot_tasktype mode, char **cursor, ot_torrent *torrent, ot_hash *hash ) {
+  /* Callers guarantee this much room: the chunk writer keeps its low
+     watermark that far from the end, the compressors hand over a buffer of
+     exactly that size */
+  char       *r          = *cursor;
+  const char *r_end      = r + OT_SCRAPE_MAXENTRYLEN;
+  size_t      seed_count = torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+  size_t      peer_count = torrent->peer_list6->peer_count + torrent->peer_list4->peer_count;
+  size_t      down_count = torrent->peer_list6->down_count + torrent->peer_list4->down_count;
+
+  switch (mode & TASK_TASK_MASK) {
+  case TASK_FULLSCRAPE:
+  default:
+    /* push hash as bencoded string */
+    *r++ = '2';
+    *r++ = '0';
+    *r++ = ':';
+    memcpy(r, hash, sizeof(ot_hash));
+    r += sizeof(ot_hash);
+    /* push rest of the scrape string */
+    fmt_append(&r, r_end, "d8:completei%zde10:downloadedi%zde10:incompletei%zdee", seed_count, down_count, peer_count - seed_count);
+
+    break;
+  case TASK_FULLSCRAPE_TPB_ASCII:
+    hex_from_hash(r, *hash);
+    r += 2 * sizeof(ot_hash);
+    fmt_append(&r, r_end, ":%zd:%zd\n", seed_count, peer_count - seed_count);
+    break;
+  case TASK_FULLSCRAPE_TPB_ASCII_PLUS:
+    hex_from_hash(r, *hash);
+    r += 2 * sizeof(ot_hash);
+    fmt_append(&r, r_end, ":%zd:%zd:%zd\n", seed_count, peer_count - seed_count, down_count);
+    break;
+  case TASK_FULLSCRAPE_TPB_BINARY:
+    memcpy(r, *hash, sizeof(ot_hash));
+    r                    += sizeof(ot_hash);
+    *(uint32_t *)(r + 0)  = htonl((uint32_t)seed_count);
+    *(uint32_t *)(r + 4)  = htonl((uint32_t)(peer_count - seed_count));
+    r                    += 8;
+    break;
+  case TASK_FULLSCRAPE_TPB_URLENCODED:
+    r += urlencoded_format(r, *hash, sizeof(ot_hash));
+    fmt_append(&r, r_end, ":%zd:%zd\n", seed_count, peer_count - seed_count);
+    break;
+  case TASK_FULLSCRAPE_TRACKERSTATE:
+    hex_from_hash(r, *hash);
+    r += 2 * sizeof(ot_hash);
+    fmt_append(&r, r_end, ":%zd:%zd\n", torrent->peer_list6->base, down_count);
+    break;
+  }
+  *cursor = r;
+}
+
+static void fullscrape_make(int taskid, ot_tasktype mode) {
+  size_t bucket;
+  char  *r, *re;
+  struct iovec iovector = {NULL, 0};
+
+  /* Setup return vector... */
+  r = iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+  if (!r)
+    return;
+
+  /* re points to low watermark */
+  re = r + OT_SCRAPE_CHUNK_SIZE - OT_SCRAPE_MAXENTRYLEN;
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE)
+    fmt_append(&r, (char *)iovector.iov_base + OT_SCRAPE_CHUNK_SIZE, "d5:filesd");
+
+  /* For each bucket... */
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    /* Get exclusive access to that bucket */
+    ot_vector  *torrents_list = mutex_bucket_lock(bucket);
+    ot_torrent *torrents      = (ot_torrent *)(torrents_list->data);
+    size_t      i;
+
+    /* For each torrent in this bucket.. */
+    for (i = 0; i < torrents_list->size; ++i) {
+      fullscrape_write_one(mode, &r, torrents + i, &torrents[i].hash);
+
+      if (r > re) {
+        iovector.iov_len = r - (char *)iovector.iov_base;
+
+        if (workqueue_pushchunked(taskid, &iovector)) {
+          free(iovector.iov_base);
+          mutex_bucket_unlock(bucket, 0);
+          return;
+        }
+        /* Allocate a fresh output buffer */
+        r = iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+        if (!r) {
+          mutex_bucket_unlock(bucket, 0);
+          return;
+        }
+
+        /* re points to low watermark */
+        re = r + OT_SCRAPE_CHUNK_SIZE - OT_SCRAPE_MAXENTRYLEN;
+      }
+    }
+
+    /* All torrents done: release lock on current bucket */
+    mutex_bucket_unlock(bucket, 0);
+
+    /* Parent thread died? */
+    if (!g_opentracker_running)
+      return;
+  }
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE)
+    fmt_append(&r, (char *)iovector.iov_base + OT_SCRAPE_CHUNK_SIZE, "ee");
+
+  /* Send rest of data */
+  iovector.iov_len = r - (char *)iovector.iov_base;
+  if (workqueue_pushchunked(taskid, &iovector))
+    free(iovector.iov_base);
+}
+
+#ifdef WANT_COMPRESSION_GZIP
+
+static void fullscrape_make_gzip(int taskid, ot_tasktype mode) {
+  size_t       bucket;
+  char        *r;
+  struct iovec iovector = {NULL, 0};
+  int          zres;
+  z_stream     strm;
+  /* Setup return vector... */
+  iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+  if (!iovector.iov_base)
+    return;
+
+  memset(&strm, 0, sizeof(strm));
+  strm.next_out  = (uint8_t *)iovector.iov_base;
+  strm.avail_out = OT_SCRAPE_CHUNK_SIZE;
+  if (deflateInit2(&strm, 7, Z_DEFLATED, 31, 9, Z_DEFAULT_STRATEGY) != Z_OK)
+    fprintf(stderr, "not ok.\n");
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE) {
+    strm.next_in  = (uint8_t *)"d5:filesd";
+    strm.avail_in = strlen("d5:filesd");
+    zres          = deflate(&strm, Z_NO_FLUSH);
+  }
+
+  /* For each bucket... */
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    /* Get exclusive access to that bucket */
+    ot_vector  *torrents_list = mutex_bucket_lock(bucket);
+    ot_torrent *torrents      = (ot_torrent *)(torrents_list->data);
+    size_t      i;
+
+    /* For each torrent in this bucket.. */
+    for (i = 0; i < torrents_list->size; ++i) {
+      char compress_buffer[OT_SCRAPE_MAXENTRYLEN];
+      r             = compress_buffer;
+      fullscrape_write_one(mode, &r, torrents + i, &torrents[i].hash);
+      strm.next_in  = (uint8_t *)compress_buffer;
+      strm.avail_in = r - compress_buffer;
+      zres          = deflate(&strm, Z_NO_FLUSH);
+      if ((zres < Z_OK) && (zres != Z_BUF_ERROR))
+        fprintf(stderr, "deflate() failed while in fullscrape_make().\n");
+
+      /* Check if there still is enough buffer left */
+      while (!strm.avail_out) {
+        iovector.iov_len = (char *)strm.next_out - (char *)iovector.iov_base;
+
+        if (workqueue_pushchunked(taskid, &iovector)) {
+          free(iovector.iov_base);
+          mutex_bucket_unlock(bucket, 0);
+          return;
+        }
+        /* Allocate a fresh output buffer */
+        iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+        if (!iovector.iov_base) {
+          fprintf(stderr, "Out of memory trying to claim ouput buffer\n");
+          deflateEnd(&strm);
+          mutex_bucket_unlock(bucket, 0);
+          return;
+        }
+        strm.next_out  = (uint8_t *)iovector.iov_base;
+        strm.avail_out = OT_SCRAPE_CHUNK_SIZE;
+        zres           = deflate(&strm, Z_NO_FLUSH);
+        if ((zres < Z_OK) && (zres != Z_BUF_ERROR))
+          fprintf(stderr, "deflate() failed while in fullscrape_make().\n");
+      }
+    }
+
+    /* All torrents done: release lock on current bucket */
+    mutex_bucket_unlock(bucket, 0);
+
+    /* Parent thread died? */
+    if (!g_opentracker_running) {
+      deflateEnd(&strm);
+      return;
+    }
+  }
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE) {
+    strm.next_in  = (uint8_t *)"ee";
+    strm.avail_in = strlen("ee");
+  }
+
+  if (deflate(&strm, Z_FINISH) < Z_OK)
+    fprintf(stderr, "deflate() failed while in fullscrape_make()'s endgame.\n");
+
+  iovector.iov_len = (char *)strm.next_out - (char *)iovector.iov_base;
+  if (workqueue_pushchunked(taskid, &iovector)) {
+    free(iovector.iov_base);
+    deflateEnd(&strm);
+    return;
+  }
+
+  /* Check if there's a last batch of data in the zlib buffer */
+  if (!strm.avail_out) {
+      /* Allocate a fresh output buffer */
+      iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+
+      if (!iovector.iov_base) {
+        fprintf(stderr, "Problem with iovec_next_chunk\n");
+        deflateEnd(&strm);
+        return;
+      }
+      strm.next_out  = iovector.iov_base;
+      strm.avail_out = OT_SCRAPE_CHUNK_SIZE;
+      if (deflate(&strm, Z_FINISH) < Z_OK)
+        fprintf(stderr, "deflate() failed while in fullscrape_make()'s endgame.\n");
+
+      /* Only pass the new buffer if there actually was some data left in the buffer */
+      iovector.iov_len = (char *)strm.next_out - (char *)iovector.iov_base;
+      if (!iovector.iov_len || workqueue_pushchunked(taskid, &iovector))
+        free(iovector.iov_base);
+  }
+
+  deflateEnd(&strm);
+}
+/* WANT_COMPRESSION_GZIP */
+#endif
+
+#ifdef WANT_COMPRESSION_ZSTD
+
+static void fullscrape_make_zstd(int taskid, ot_tasktype mode) {
+  int            bucket;
+  char          *r;
+  struct iovec   iovector = {NULL, 0};
+  ZSTD_CCtx     *zstream = ZSTD_createCCtx();
+  ZSTD_inBuffer  inbuf;
+  ZSTD_outBuffer outbuf;
+  size_t         more_bytes;
+
+  if (!zstream)
+    return;
+
+  /* Setup return vector... */
+  iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+  if (!iovector.iov_base) {
+    ZSTD_freeCCtx(zstream);
+    return;
+  }
+
+  /* Working with a compression level 6 is half as fast as level 3, but
+     seems to be the last reasonable bump that's worth extra cpu */
+  ZSTD_CCtx_setParameter(zstream, ZSTD_c_compressionLevel, 6);
+
+  outbuf.dst  = iovector.iov_base;
+  outbuf.size = OT_SCRAPE_CHUNK_SIZE;
+  outbuf.pos  = 0;
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE) {
+    inbuf.src  = (const void *)"d5:filesd";
+    inbuf.size = strlen("d5:filesd");
+    inbuf.pos  = 0;
+    ZSTD_compressStream2(zstream, &outbuf, &inbuf, ZSTD_e_continue);
+  }
+
+  /* For each bucket... */
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    /* Get exclusive access to that bucket */
+    ot_vector  *torrents_list = mutex_bucket_lock(bucket);
+    ot_torrent *torrents      = (ot_torrent *)(torrents_list->data);
+    size_t      i;
+
+    /* For each torrent in this bucket.. */
+    for (i = 0; i < torrents_list->size; ++i) {
+      char compress_buffer[OT_SCRAPE_MAXENTRYLEN];
+      r             = compress_buffer;
+      fullscrape_write_one(mode, &r, torrents + i, &torrents[i].hash);
+      inbuf.src     = compress_buffer;
+      inbuf.size    = r - compress_buffer;
+      inbuf.pos     = 0;
+      ZSTD_compressStream2(zstream, &outbuf, &inbuf, ZSTD_e_continue);
+
+      /* Check if there still is enough buffer left */
+      while (outbuf.pos + OT_SCRAPE_MAXENTRYLEN > outbuf.size) {
+        iovector.iov_len = outbuf.size;
+
+        if (workqueue_pushchunked(taskid, &iovector)) {
+          free(iovector.iov_base);
+          ZSTD_freeCCtx(zstream);
+          return mutex_bucket_unlock(bucket, 0);
+        }
+        /* Allocate a fresh output buffer */
+        iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+        if (!iovector.iov_base) {
+          fprintf(stderr, "Out of memory trying to claim ouput buffer\n");
+          ZSTD_freeCCtx(zstream);
+          return mutex_bucket_unlock(bucket, 0);
+        }
+
+        outbuf.dst  = iovector.iov_base;
+        outbuf.size = OT_SCRAPE_CHUNK_SIZE;
+        outbuf.pos  = 0;
+
+        ZSTD_compressStream2(zstream, &outbuf, &inbuf, ZSTD_e_continue);
+      }
+    }
+
+    /* All torrents done: release lock on current bucket */
+    mutex_bucket_unlock(bucket, 0);
+
+    /* Parent thread died? */
+    if (!g_opentracker_running)
+      return;
+  }
+
+  if ((mode & TASK_TASK_MASK) == TASK_FULLSCRAPE) {
+    inbuf.src  = (const void *)"ee";
+    inbuf.size = strlen("ee");
+    inbuf.pos  = 0;
+  }
+
+  more_bytes = ZSTD_compressStream2(zstream, &outbuf, &inbuf, ZSTD_e_end);
+
+  iovector.iov_len = outbuf.pos;
+  if (workqueue_pushchunked(taskid, &iovector)) {
+    free(iovector.iov_base);
+    ZSTD_freeCCtx(zstream);
+    return;
+  }
+
+  /* Check if there's a last batch of data in the zlib buffer */
+  if (more_bytes) {
+      /* Allocate a fresh output buffer */
+      iovector.iov_base = malloc(OT_SCRAPE_CHUNK_SIZE);
+
+      if (!iovector.iov_base) {
+        fprintf(stderr, "Problem with iovec_next_chunk\n");
+        ZSTD_freeCCtx(zstream);
+        return;
+      }
+
+      outbuf.dst  = iovector.iov_base;
+      outbuf.size = OT_SCRAPE_CHUNK_SIZE;
+      outbuf.pos  = 0;
+
+      ZSTD_compressStream2(zstream, &outbuf, &inbuf, ZSTD_e_end);
+
+      /* Only pass the new buffer if there actually was some data left in the buffer */
+      iovector.iov_len = outbuf.pos;
+      if (!iovector.iov_len || workqueue_pushchunked(taskid, &iovector))
+        free(iovector.iov_base);
+  }
+
+  ZSTD_freeCCtx(zstream);
+}
+/* WANT_COMPRESSION_ZSTD */
+#endif
+
+/* WANT_FULLSCRAPE */
+#endif
diff --git a/src/ot_fullscrape.h b/src/ot_fullscrape.h
new file mode 100644
index 0000000..8d11cd3
--- /dev/null
+++ b/src/ot_fullscrape.h
@@ -0,0 +1,23 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_FULLSCRAPE_H__
+#define OT_FULLSCRAPE_H__
+
+#ifdef WANT_FULLSCRAPE
+
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+
+void fullscrape_init(void);
+void fullscrape_deinit(void);
+void fullscrape_deliver(int64_t sock, ot_tasktype tasktype);
+
+#else
+
+#define fullscrape_init()
+#define fullscrape_deinit()
+
+#endif
+
+#endif
diff --git a/src/ot_hex.c b/src/ot_hex.c
new file mode 100644
index 0000000..b537094
--- /dev/null
+++ b/src/ot_hex.c
@@ -0,0 +1,56 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdint.h>
+#include <string.h>
+
+/* Opentracker */
+#include "ot_hex.h"
+
+int hex_value(int c) {
+  unsigned char u = (unsigned char)c;
+
+  if (u >= '0' && u <= '9')
+    return u - '0';
+  u |= 0x20; /* fold upper case onto lower, digits are already handled */
+  if (u >= 'a' && u <= 'f')
+    return u - 'a' + 10;
+  return -1;
+}
+
+int hex_isdigit(int c) { return hex_value(c) >= 0; }
+
+char *hex_from_hash(char *dest, const uint8_t *hash) {
+  static const char digits[] = "0123456789ABCDEF";
+  char             *d        = dest;
+  size_t            i;
+
+  for (i = 0; i < sizeof(ot_hash); ++i) {
+    *d++ = digits[hash[i] >> 4];
+    *d++ = digits[hash[i] & 15];
+  }
+  *d = 0;
+  return dest;
+}
+
+int hex_to_hash(ot_hash hash, const char *src) {
+  uint8_t decoded[sizeof(ot_hash)];
+  size_t  i;
+
+  for (i = 0; i < sizeof(ot_hash); ++i) {
+    int high, low;
+
+    /* Tested one character at a time so that a string ending early stops us
+       at its terminator rather than one byte past it */
+    if ((high = hex_value((unsigned char)src[2 * i])) < 0)
+      return 0;
+    if ((low = hex_value((unsigned char)src[2 * i + 1])) < 0)
+      return 0;
+
+    decoded[i] = (uint8_t)((high << 4) | low);
+  }
+
+  memcpy(hash, decoded, sizeof(decoded));
+  return 1;
+}
diff --git a/src/ot_hex.h b/src/ot_hex.h
new file mode 100644
index 0000000..ddbbb44
--- /dev/null
+++ b/src/ot_hex.h
@@ -0,0 +1,27 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_HEX_H__
+#define OT_HEX_H__
+
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+/* Write hash as forty upper case hex digits followed by a terminating zero.
+   dest must have room for forty one bytes. Returns dest. */
+char *hex_from_hash(char *dest, const uint8_t *hash);
+
+/* Read forty hex digits from src into hash. Returns non-zero on success.
+   On failure hash is left untouched and no byte of src beyond the offending
+   character is read, so src need not be forty characters long. */
+int   hex_to_hash(ot_hash hash, const char *src);
+
+/* Non-zero if c is a hexadecimal digit, in either case. */
+int   hex_isdigit(int c);
+
+/* The value of a hexadecimal digit, or -1 if c is not one. Shared with the
+   address scanner so that both agree on what a digit is. */
+int   hex_value(int c);
+
+#endif
diff --git a/src/ot_http.c b/src/ot_http.c
new file mode 100644
index 0000000..96b8f4e
--- /dev/null
+++ b/src/ot_http.c
@@ -0,0 +1,810 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#define _GNU_SOURCE
+#include <arpa/inet.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_fullscrape.h"
+#include "ot_http.h"
+#include "ot_iovec.h"
+#include "ot_ip.h"
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+#include "ot_scan.h"
+#include "ot_event.h"
+#include "ot_fdstate.h"
+#include "ot_vector.h"
+#include "ot_fmt.h"
+#include "ot_stats.h"
+#include "ot_urlencoded.h"
+#include "trackerlogic.h"
+
+#define OT_MAXMULTISCRAPE_COUNT 64
+extern const char *g_redirecturl;
+
+const char  *g_stats_path;
+ssize_t      g_stats_path_len;
+
+enum { SUCCESS_HTTP_HEADER_LENGTH = 80, SUCCESS_HTTP_SIZE_OFF = 17 };
+
+struct http_data *http_adopt(const int64_t sock) {
+  struct http_data *cookie = fdstate_cookie(sock), *heap;
+  int               interest;
+
+  if (!cookie || !(cookie->flag & STRUCT_HTTP_FLAG_ONSTACK))
+    return cookie;
+
+  if (!(heap = malloc(sizeof(*heap))))
+    return NULL;
+
+  *heap = *cookie;
+  heap->flag &= ~STRUCT_HTTP_FLAG_ONSTACK;
+
+  /* Publishing the cookie is what lets another thread reach this connection,
+     so nothing may touch it afterwards, not even to read what it asked for */
+  interest = heap->interest;
+  fdstate_set_cookie((int)sock, heap);
+
+  if (event_add((int)sock, interest, fdstate_generation((int)sock)) == -1) {
+    fdstate_set_cookie((int)sock, cookie);
+    free(heap);
+    return NULL;
+  }
+  return heap;
+}
+
+/* Give up a connection: the one place that knows everything hanging off it. */
+void http_close(const int64_t sock) {
+  struct http_data *cookie = fdstate_cookie(sock);
+
+  fdstate_close((int)sock);
+
+  if (cookie) {
+    if (cookie->batch)
+      batch_reset(cookie->batch);
+    free(cookie->batch);
+    buf_reset(&cookie->request);
+    if (cookie->flag & (STRUCT_HTTP_FLAG_WAITINGFORTASK | STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER))
+      workqueue_canceltask(sock);
+    if (!(cookie->flag & STRUCT_HTTP_FLAG_ONSTACK))
+      free(cookie);
+  }
+
+  event_close((int)sock);
+}
+
+static void http_senddata(const int64_t sock, struct ot_workstruct *ws) {
+  struct http_data *cookie = fdstate_cookie(sock);
+  ssize_t           written_size;
+
+  if (!cookie) {
+    http_close(sock);
+    return;
+  }
+
+  /* whoever sends data is not interested in its input buffer */
+  if (ws->keep_alive && ws->header_size != ws->request_size) {
+    size_t rest = ws->request_size - ws->header_size;
+    if (cookie->request.data) {
+      memmove(cookie->request.data, ws->request + ws->header_size, rest);
+      buf_truncate(&cookie->request, rest);
+    } else if (buf_cat(&cookie->request, ws->request + ws->header_size, rest)) {
+      /* Without room for what the client pipelined behind this request, answer
+         this one and let the connection close, rather than keeping it open
+         around a request we have silently dropped */
+      buf_reset(&cookie->request);
+      ws->keep_alive = 0;
+    }
+  } else
+    buf_reset(&cookie->request);
+
+  written_size = write(sock, ws->reply, ws->reply_size);
+  /* A send buffer with no room in it is not a failure: nothing went out, so
+     the whole reply goes into the batch below and leaves when the socket
+     drains. Only a real error ends the connection here. */
+  if (written_size < 0 && (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR))
+    written_size = 0;
+
+  if ((written_size < 0) || ((written_size == ws->reply_size) && !ws->keep_alive)) {
+    http_close(sock);
+    return;
+  }
+
+  if (written_size < ws->reply_size) {
+    char   *outbuf;
+
+    if (!(outbuf = malloc(ws->reply_size - written_size))) {
+      http_close(sock);
+      return;
+    }
+
+    memcpy(outbuf, ws->reply + written_size, ws->reply_size - written_size);
+    if (!cookie->batch) {
+      cookie->batch = calloc(1, sizeof(ot_batch));
+      if (!cookie->batch) {
+        free(outbuf);
+        http_close(sock);
+        return;
+      }
+    }
+
+    batch_add(cookie->batch, outbuf, ws->reply_size - written_size);
+
+    /* writeable short data sockets just have a tcp timeout */
+    if (!ws->keep_alive)
+      fdstate_set_expiry(sock, 0);
+    http_interest_set(sock, cookie, EVENT_OUT);
+  }
+}
+
+#define HTTPERROR_302            return http_issue_error(sock, ws, CODE_HTTPERROR_302)
+#define HTTPERROR_400            return http_issue_error(sock, ws, CODE_HTTPERROR_400)
+#define HTTPERROR_400_PARAM      return http_issue_error(sock, ws, CODE_HTTPERROR_400_PARAM)
+#define HTTPERROR_400_COMPACT    return http_issue_error(sock, ws, CODE_HTTPERROR_400_COMPACT)
+#define HTTPERROR_400_DOUBLEHASH return http_issue_error(sock, ws, CODE_HTTPERROR_400_PARAM)
+#define HTTPERROR_402_NOTMODEST  return http_issue_error(sock, ws, CODE_HTTPERROR_402_NOTMODEST)
+#define HTTPERROR_403_IP         return http_issue_error(sock, ws, CODE_HTTPERROR_403_IP)
+#define HTTPERROR_404            return http_issue_error(sock, ws, CODE_HTTPERROR_404)
+#define HTTPERROR_500            return http_issue_error(sock, ws, CODE_HTTPERROR_500)
+/* A connection is either being read or being written, never both, so what it
+   waits for is set outright rather than added to and taken away again. The
+   event layer only hears about it when the answer changes. */
+void http_interest_set(const int64_t sock, struct http_data *cookie, int what) {
+  if (cookie->interest == what)
+    return;
+  cookie->interest = what;
+  /* Still on a stack, so not in the event loop yet: whoever adopts this
+     connection registers whatever it asked for last */
+  if (cookie->flag & STRUCT_HTTP_FLAG_ONSTACK)
+    return;
+  event_modify((int)sock, what, fdstate_generation((int)sock));
+}
+
+ssize_t http_issue_error(const int64_t sock, struct ot_workstruct *ws, int code) {
+  const char *error_code[] = {"302 Found",      "400 Invalid Request", "400 Invalid Request", "400 Invalid Request",      "402 Payment Required",
+                        "403 Not Modest", "403 Access Denied",   "404 Not Found",       "500 Internal Server Error"};
+  const char *title  = error_code[code];
+
+  ws->reply          = ws->outbuf;
+  if (code == CODE_HTTPERROR_302)
+    ws->reply_size = snprintf(ws->reply, G_OUTBUF_SIZE, "HTTP/1.0 302 Found\r\nContent-Length: 0\r\nLocation: %s\r\n\r\n", g_redirecturl);
+  else
+    ws->reply_size = snprintf(ws->reply, G_OUTBUF_SIZE, "HTTP/1.0 %s\r\nContent-Type: text/html\r\nContent-Length: %zd\r\n\r\n<title>%s</title>\n", title,
+                              strlen(title) + 16 - 4, title + 4);
+
+#ifdef _DEBUG_HTTPERROR
+  fprintf(stderr, "DEBUG: invalid request was: %s\n", ws->debugbuf);
+#endif
+  stats_issue_event(ws, EVENT_FAILED, FLAG_TCP, code);
+  http_senddata(sock, ws);
+  return ws->reply_size = -2;
+}
+
+ssize_t http_sendiovecdata(const int64_t sock, struct ot_workstruct *ws, size_t iovec_entries, struct iovec *iovector, int is_partial) {
+  struct http_data *cookie = fdstate_cookie(sock);
+  char             *header;
+  const char       *encoding = "";
+  size_t            header_size, size = iovec_length(&iovec_entries, (const struct iovec **)&iovector);
+
+  /* No cookie? Bad socket. Leave. */
+  if (!cookie) {
+    iovec_free(&iovec_entries, &iovector);
+    HTTPERROR_500;
+  }
+
+  /* Descriptor numbers get recycled, so a result can only belong to this
+     connection if this connection is in fact waiting for one. */
+  if (!(cookie->flag & (STRUCT_HTTP_FLAG_WAITINGFORTASK | STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER))) {
+    iovec_free(&iovec_entries, &iovector);
+    return 0;
+  }
+
+  /* If this socket collected request in a buffer, free it now */
+  buf_reset(&cookie->request);
+
+  /* If we came here, wait for the answer is over */
+  if (cookie->flag & STRUCT_HTTP_FLAG_WAITINGFORTASK) {
+    http_interest_set(sock, cookie, 0);
+    cookie->flag &= ~STRUCT_HTTP_FLAG_WAITINGFORTASK;
+  }
+
+  if (iovec_entries) {
+
+    if (cookie->flag & STRUCT_HTTP_FLAG_ZSTD)
+      encoding = "Content-Encoding: zstd\r\n";
+    else if (cookie->flag & STRUCT_HTTP_FLAG_GZIP)
+      encoding = "Content-Encoding: gzip\r\n";
+    else if (cookie->flag & STRUCT_HTTP_FLAG_BZIP2)
+      encoding = "Content-Encoding: bzip2\r\n";
+
+    if (!(cookie->flag & STRUCT_HTTP_FLAG_CHUNKED))
+      header_size = asprintf(&header, "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n%sContent-Length: %zd\r\n\r\n", encoding, size);
+    else {
+      if (!(cookie->flag & STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER)) {
+        header_size =
+            asprintf(&header, "HTTP/1.1 200 OK\r\nContent-Type: application/octet-stream\r\n%sTransfer-Encoding: chunked\r\n\r\n%zx\r\n", encoding, size);
+        cookie->flag |= STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER;
+      } else
+        header_size = asprintf(&header, "%zx\r\n", size);
+    }
+    if (!header) {
+      iovec_free(&iovec_entries, &iovector);
+      HTTPERROR_500;
+    }
+
+    if (!cookie->batch) {
+      cookie->batch = calloc(1, sizeof(ot_batch));
+      if (!cookie->batch) {
+        free(header);
+        iovec_free(&iovec_entries, &iovector);
+        HTTPERROR_500;
+      }
+    }
+
+    batch_add(cookie->batch, header, header_size);
+    batch_add_vector(cookie->batch, iovector, iovec_entries);
+    free(iovector);
+
+    if (cookie->flag & STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER)
+      batch_add_copy(cookie->batch, "\r\n", 2);
+  }
+
+  if ((cookie->flag & STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER) && cookie->batch && !is_partial) {
+    batch_add_copy(cookie->batch, "0\r\n\r\n", 5);
+    cookie->flag &= ~STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER;
+  }
+
+  fdstate_set_expiry(sock, time_future_seconds(OT_CLIENT_TIMEOUT_SEND));
+  http_interest_set(sock, cookie, EVENT_OUT);
+  return 0;
+}
+
+static ssize_t http_handle_stats(const int64_t sock, struct ot_workstruct *ws, char *read_ptr) {
+  static const ot_keywords keywords_main[] = {{"mode", 1}, {"format", 2}, {"info_hash", 3}, {NULL, -3}};
+  static const ot_keywords keywords_mode[] = {{"peer", TASK_STATS_PEERS},
+                                              {"conn", TASK_STATS_CONNS},
+                                              {"scrp", TASK_STATS_SCRAPE},
+                                              {"udp4", TASK_STATS_UDP},
+                                              {"tcp4", TASK_STATS_TCP},
+                                              {"torr", TASK_STATS_TORRENTS},
+                                              {"fscr", TASK_STATS_FULLSCRAPE},
+                                              {"s24s", TASK_STATS_SLASH24S},
+                                              {"tpbs", TASK_STATS_TPB},
+                                              {"herr", TASK_STATS_HTTPERRORS},
+                                              {"completed", TASK_STATS_COMPLETED},
+                                              {"top100", TASK_STATS_TOP100},
+                                              {"top10", TASK_STATS_TOP10},
+                                              {"renew", TASK_STATS_RENEW},
+                                              {"syncs", TASK_STATS_SYNCS},
+                                              {"everything", TASK_STATS_EVERYTHING},
+                                              {"statedump", TASK_FULLSCRAPE_TRACKERSTATE},
+                                              {"woodpeckers", TASK_STATS_WOODPECKERS},
+#ifdef WANT_LOG_NUMWANT
+                                              {"numwants", TASK_STATS_NUMWANTS},
+#endif
+                                              {NULL, -3}};
+  static const ot_keywords keywords_format[] = {{"bin", TASK_FULLSCRAPE_TPB_BINARY},      {"ben", TASK_FULLSCRAPE},
+                                                {"url", TASK_FULLSCRAPE_TPB_URLENCODED},  {"txt", TASK_FULLSCRAPE_TPB_ASCII},
+                                                {"txtp", TASK_FULLSCRAPE_TPB_ASCII_PLUS}, {NULL, -3}};
+
+  struct http_data *cookie = fdstate_cookie(sock);
+  char             *reply;
+  int               mode = TASK_STATS_PEERS, scanon = 1, format = 0;
+
+  /* A socket without one is a dead socket, which is what http_sendiovecdata
+     already answers 500 to. */
+  if (!cookie)
+    HTTPERROR_500;
+
+#ifdef WANT_RESTRICT_STATS
+  if (!accesslist_is_blessed(cookie->ip, OT_PERMISSION_MAY_STAT))
+    HTTPERROR_403_IP;
+#endif
+
+  while (scanon) {
+    switch (urlencoded_match_keyword(keywords_main, &read_ptr, SCAN_SEARCHPATH_PARAM)) {
+    case -2:
+      scanon = 0;
+      break; /* TERMINATOR */
+    case -1:
+      HTTPERROR_400_PARAM; /* PARSE ERROR */
+    case -3:
+      urlencoded_skip_value(&read_ptr);
+      break;
+    case 1: /* matched "mode" */
+      if ((mode = urlencoded_match_keyword(keywords_mode, &read_ptr, SCAN_SEARCHPATH_VALUE)) <= 0)
+        HTTPERROR_400_PARAM;
+      break;
+    case 2: /* matched "format" */
+      if ((format = urlencoded_match_keyword(keywords_format, &read_ptr, SCAN_SEARCHPATH_VALUE)) <= 0)
+        HTTPERROR_400_PARAM;
+      break;
+    case 3:
+      HTTPERROR_400_PARAM; /* If the stats URL was mistakenly added as announce URL, return a 400 */
+    }
+  }
+
+#ifdef WANT_FULLSCRAPE
+  if (mode == TASK_FULLSCRAPE_TRACKERSTATE) {
+    format = mode;
+    mode   = TASK_STATS_TPB;
+  }
+
+  if (mode == TASK_STATS_TPB) {
+#ifdef WANT_COMPRESSION_GZIP
+    ws->request[ws->request_size - 1] = 0;
+#ifndef WANT_COMPRESSION_GZIP_ALWAYS
+    if (strstr(read_ptr - 1, "gzip")) {
+#endif
+      cookie->flag |= STRUCT_HTTP_FLAG_GZIP;
+      format       |= TASK_FLAG_GZIP;
+#ifndef WANT_COMPRESSION_GZIP_ALWAYS
+    }
+#endif
+#endif
+    cookie->flag |= STRUCT_HTTP_FLAG_WAITINGFORTASK | STRUCT_HTTP_FLAG_CHUNKED;
+
+    /* Clients waiting for us should not easily timeout */
+    fdstate_set_expiry(sock, 0);
+    http_interest_set(sock, cookie, 0);
+
+    /* Everything this connection needs has been written, so it can be given
+       a home of its own and only then be made reachable by a worker thread */
+    if (!http_adopt(sock))
+      HTTPERROR_500;
+    fullscrape_deliver(sock, format);
+    return ws->reply_size = -2;
+  }
+#endif
+
+  /* default format for now */
+  if ((mode & TASK_CLASS_MASK) == TASK_STATS) {
+
+    cookie->flag |= STRUCT_HTTP_FLAG_WAITINGFORTASK;
+
+    /* Complex stats also include expensive memory debugging tools */
+    fdstate_set_expiry(sock, 0);
+
+    if (!http_adopt(sock))
+      HTTPERROR_500;
+    stats_deliver(sock, mode);
+    return ws->reply_size = -2;
+  }
+
+  /* Simple stats can be answerred immediately */
+  reply = ws->reply;
+  return_stats_for_tracker(&reply, ws->outbuf + G_OUTBUF_SIZE, mode, 0);
+  return ws->reply_size = reply - ws->reply;
+}
+
+#ifdef WANT_MODEST_FULLSCRAPES
+static pthread_mutex_t g_modest_fullscrape_mutex = PTHREAD_MUTEX_INITIALIZER;
+static ot_vector       g_modest_fullscrape_timeouts;
+typedef struct {
+  ot_ip6  ip;
+  ot_time last_fullscrape;
+} ot_scrape_log;
+#endif
+
+#ifdef WANT_FULLSCRAPE
+static ssize_t http_handle_fullscrape(const int64_t sock, struct ot_workstruct *ws) {
+  struct http_data *cookie = fdstate_cookie(sock);
+  int               format = 0;
+
+#ifdef WANT_MODEST_FULLSCRAPES
+  {
+    ot_scrape_log this_peer, *new_peer;
+    int           exactmatch;
+    memcpy(this_peer.ip, cookie->ip, sizeof(ot_ip6));
+    this_peer.last_fullscrape = time_now_seconds();
+    pthread_mutex_lock(&g_modest_fullscrape_mutex);
+    new_peer = vector_find_or_insert(&g_modest_fullscrape_timeouts, &this_peer, sizeof(ot_scrape_log), sizeof(ot_ip6), &exactmatch);
+    if (!new_peer) {
+      pthread_mutex_unlock(&g_modest_fullscrape_mutex);
+      HTTPERROR_500;
+    }
+    if (exactmatch && (this_peer.last_fullscrape - new_peer->last_fullscrape) < OT_MODEST_PEER_TIMEOUT) {
+      pthread_mutex_unlock(&g_modest_fullscrape_mutex);
+      HTTPERROR_402_NOTMODEST;
+    }
+    memcpy(new_peer, &this_peer, sizeof(ot_scrape_log));
+    pthread_mutex_unlock(&g_modest_fullscrape_mutex);
+  }
+#endif
+
+
+#if defined(WANT_COMPRESSION_GZIP) || defined(WANT_COMPRESSION_ZSTD)
+  ws->request[ws->request_size - 1] = 0;
+#ifdef WANT_COMPRESSION_GZIP
+  if (strstr(ws->request, "gzip")) {
+    cookie->flag |= STRUCT_HTTP_FLAG_GZIP;
+    format       |= TASK_FLAG_GZIP;
+  }
+#endif
+#ifdef WANT_COMPRESSION_ZSTD
+  if (strstr(ws->request, "zstd")) {
+    cookie->flag |= STRUCT_HTTP_FLAG_ZSTD;
+    format       |= TASK_FLAG_ZSTD;
+  }
+#endif
+
+#if defined(WANT_COMPRESSION_ZSTD) && defined(WANT_COMPRESSION_ZSTD_ALWAYS)
+  cookie->flag |= STRUCT_HTTP_FLAG_ZSTD;
+  format       |= TASK_FLAG_ZSTD;
+#endif
+
+#if defined(WANT_COMPRESSION_GZIP) && defined(WANT_COMPRESSION_GZIP_ALWAYS)
+  cookie->flag |= STRUCT_HTTP_FLAG_GZIP;
+  format       |= TASK_FLAG_GZIP;
+#endif
+#endif
+
+  stats_issue_event(ws, EVENT_FULLSCRAPE_REQUEST, 0, (uintptr_t)cookie->ip);
+
+#ifdef _DEBUG_HTTPERROR
+  fprintf(stderr, "%s", ws->debugbuf);
+#endif
+
+  /* Pass this task to the worker thread */
+  cookie->flag |= STRUCT_HTTP_FLAG_WAITINGFORTASK | STRUCT_HTTP_FLAG_CHUNKED;
+  /* Clients waiting for us should not easily timeout */
+  fdstate_set_expiry(sock, 0);
+  http_interest_set(sock, cookie, 0);
+
+  if (!http_adopt(sock))
+    HTTPERROR_500;
+  fullscrape_deliver(sock, format);
+  return ws->reply_size = -2;
+}
+#endif
+
+static int compare_hash(const void *left, const void *right) { return memcmp(left, right, sizeof(ot_hash)); }
+
+static ssize_t http_handle_scrape(const int64_t sock, struct ot_workstruct *ws, char *read_ptr) {
+  static const ot_keywords keywords_scrape[] = {{"info_hash", 1}, {NULL, -3}};
+
+  ot_hash *multiscrape_buf = (ot_hash *)ws->request;
+  char    *reply           = ws->reply;
+  int      scanon          = 1;
+  size_t   i, unique, numwant = 0;
+
+  /* This is to hack around stupid clients that send "scrape ?info_hash" */
+  if (read_ptr[-1] != '?') {
+    while ((*read_ptr != '?') && (*read_ptr != '\n'))
+      ++read_ptr;
+    if (*read_ptr == '\n')
+      HTTPERROR_400_PARAM;
+    ++read_ptr;
+  }
+
+  while (scanon) {
+    switch (urlencoded_match_keyword(keywords_scrape, &read_ptr, SCAN_SEARCHPATH_PARAM)) {
+    case -2:
+      scanon = 0;
+      break; /* TERMINATOR */
+    default:
+      HTTPERROR_400_PARAM; /* PARSE ERROR */
+    case -3:
+      urlencoded_skip_value(&read_ptr);
+      break;
+    case 1: /* matched "info_hash" */
+      /* ignore this, when we have less than 20 bytes */
+      if (urlencoded_parse(&read_ptr, (char *)(multiscrape_buf + numwant++), SCAN_SEARCHPATH_VALUE) != (ssize_t)sizeof(ot_hash))
+        HTTPERROR_400_PARAM;
+      break;
+    }
+  }
+
+  /* No info_hash found? Inform user */
+  if (!numwant)
+    HTTPERROR_400_PARAM;
+
+  /* Limit number of hashes to process */
+  if (numwant > OT_MAXMULTISCRAPE_COUNT)
+    numwant = OT_MAXMULTISCRAPE_COUNT;
+
+  /* A bencoded dictionary has its keys in order and names each one once, so
+     the answer cannot just follow the order the client asked in */
+  qsort(multiscrape_buf, numwant, sizeof(ot_hash), compare_hash);
+  for (i = unique = 1; i < numwant; ++i)
+    if (memcmp(multiscrape_buf[i], multiscrape_buf[unique - 1], sizeof(ot_hash)))
+      memcpy(multiscrape_buf[unique++], multiscrape_buf[i], sizeof(ot_hash));
+  numwant = unique;
+
+  /* Enough for http header + whole scrape string */
+  return_tcp_scrape_for_torrent((const ot_hash *)multiscrape_buf, numwant, &reply, ws->outbuf + G_OUTBUF_SIZE);
+  ws->reply_size = reply - ws->reply;
+  stats_issue_event(ws, EVENT_SCRAPE, FLAG_TCP, ws->reply_size);
+  return ws->reply_size;
+}
+
+#ifdef WANT_LOG_NUMWANT
+unsigned long long numwants[201];
+#endif
+
+#if defined(WANT_KEEPALIVE) || defined(WANT_IP_FROM_PROXY)
+static char *http_header(char *data, size_t byte_count, const char *header) {
+  size_t i;
+  long   sl = strlen(header);
+  for (i = 0; i + sl + 2 < byte_count; ++i) {
+    if (data[i] != '\n' || data[i + sl + 1] != ':')
+      continue;
+    if (strncasecmp(data + i + 1, header, sl))
+      continue;
+    data += i + sl + 2;
+    while (*data == ' ' || *data == '\t')
+      ++data;
+    return data;
+  }
+  return 0;
+}
+#endif
+
+static ot_keywords keywords_announce[] = {{"port", 1},    {"left", 2}, {"event", 3}, {"numwant", 4}, {"compact", 5}, {"compact6", 5}, {"info_hash", 6},
+#ifdef WANT_IP_FROM_QUERY_STRING
+                                          {"ip", 7},
+#endif
+                                          {"peer_id", 8}, {NULL, -3}};
+static ot_keywords keywords_announce_event[] = {{"completed", 1}, {"stopped", 2}, {NULL, -3}};
+
+/* For the replies that are one fixed string and nothing else, where the only
+   thing the caller wants back is how long it turned out */
+static ssize_t     reply_literal(struct ot_workstruct *ws, const char *text) {
+  char *reply = ws->reply;
+
+  fmt_bytes(&reply, ws->outbuf + G_OUTBUF_SIZE, text, strlen(text));
+  return reply - ws->reply;
+}
+
+static ssize_t     http_handle_announce(const int64_t sock, struct ot_workstruct *ws, char *read_ptr) {
+  size_t            numwant;
+  int64_t           tmp;
+  int               scanon;
+  unsigned short    port = 0;
+  char             *write_ptr;
+  ssize_t           len;
+  struct http_data *cookie = fdstate_cookie(sock);
+
+  /* This is to hack around stupid clients that send "announce ?info_hash" */
+  if (read_ptr[-1] != '?') {
+    while ((*read_ptr != '?') && (*read_ptr != '\n'))
+      ++read_ptr;
+    if (*read_ptr == '\n')
+      HTTPERROR_400_PARAM;
+    ++read_ptr;
+  }
+
+#ifdef WANT_IP_FROM_PROXY
+  if (accesslist_is_blessed(cookie->ip, OT_PERMISSION_MAY_PROXY)) {
+    ot_ip6 proxied_ip;
+    char  *fwd = http_header(ws->request, ws->header_size, "x-forwarded-for");
+    if (fwd && ip_parse(fwd, proxied_ip)) {
+      OT_SETIP(ws->peer, proxied_ip);
+    } else
+      OT_SETIP(ws->peer, cookie->ip);
+  } else
+#endif
+    OT_SETIP(ws->peer, cookie->ip);
+
+  ws->peer_id = NULL;
+  ws->hash    = NULL;
+
+  OT_SETPORT(ws->peer, &port);
+  OT_PEERFLAG(ws->peer) = 0;
+  numwant               = 50;
+  scanon                = 1;
+
+  while (scanon) {
+    switch (urlencoded_match_keyword(keywords_announce, &read_ptr, SCAN_SEARCHPATH_PARAM)) {
+    case -2:
+      scanon = 0;
+      break; /* TERMINATOR */
+    case -1:
+      HTTPERROR_400_PARAM; /* PARSE ERROR */
+    case -3:
+      urlencoded_skip_value(&read_ptr);
+      break;
+    case 1: /* matched "port" */
+      len = urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE);
+      if ((len <= 0) || scan_int(write_ptr, len, &tmp) || (tmp > 0xffff))
+        HTTPERROR_400_PARAM;
+      port = htons((uint16_t)tmp);
+      OT_SETPORT(&ws->peer, &port);
+      break;
+    case 2: /* matched "left" */
+      if ((len = urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE)) <= 0)
+        HTTPERROR_400_PARAM;
+      if (scan_int(write_ptr, len, &tmp))
+        tmp = 0;
+      if (!tmp)
+        OT_PEERFLAG(&ws->peer) |= PEER_FLAG_SEEDING;
+      break;
+    case 3: /* matched "event" */
+      switch (urlencoded_match_keyword(keywords_announce_event, &read_ptr, SCAN_SEARCHPATH_VALUE)) {
+      case -1:
+        HTTPERROR_400_PARAM;
+      case 1: /* matched "completed" */
+        OT_PEERFLAG(&ws->peer) |= PEER_FLAG_COMPLETED;
+        break;
+      case 2: /* matched "stopped" */
+        OT_PEERFLAG(&ws->peer) |= PEER_FLAG_STOPPED;
+        break;
+      default:
+        break;
+      }
+      break;
+    case 4: /* matched "numwant" */
+      len = urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE);
+      if ((len <= 0) || scan_int(write_ptr, len, &tmp))
+        HTTPERROR_400_PARAM;
+      if (tmp < 0)
+        tmp = 50;
+      if (tmp > 200)
+        tmp = 200;
+      numwant = (size_t)tmp;
+      break;
+    case 5: /* matched "compact" */
+      len = urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE);
+      if ((len <= 0) || scan_int(write_ptr, len, &tmp))
+        HTTPERROR_400_PARAM;
+      if (!tmp)
+        HTTPERROR_400_COMPACT;
+      break;
+    case 6: /* matched "info_hash" */
+      if (ws->hash)
+        HTTPERROR_400_DOUBLEHASH;
+      /* ignore this, when we have less than 20 bytes */
+      if (urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE) != 20)
+        HTTPERROR_400_PARAM;
+      ws->hash = (ot_hash *)write_ptr;
+      break;
+#ifdef WANT_IP_FROM_QUERY_STRING
+    case 7: /* matched "ip" */
+    {
+      char *tmp_buf1 = ws->reply, *tmp_buf2 = ws->reply + 16;
+      len           = urlencoded_parse(&read_ptr, tmp_buf2, SCAN_SEARCHPATH_VALUE);
+      tmp_buf2[len] = 0;
+      if ((len <= 0) || ip_parse(tmp_buf2, tmp_buf1) != (size_t)len)
+        HTTPERROR_400_PARAM;
+      OT_SETIP(&ws->peer, tmp_buf1);
+    } break;
+#endif
+    case 8: /* matched "peer_id" */
+      /* ignore this, when we have less than 20 bytes */
+      if (urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_SEARCHPATH_VALUE) != 20)
+        HTTPERROR_400_PARAM;
+      ws->peer_id = write_ptr;
+      break;
+    }
+  }
+
+#ifdef WANT_LOG_NUMWANT
+  numwants[numwant]++;
+#endif
+
+  /* XXX DEBUG
+  stats_issue_event(ws, EVENT_ACCEPT, FLAG_TCP, (uintptr_t)ws->reply );
+  */
+
+  /* Scanned whole query string */
+  if (!ws->hash)
+    return ws->reply_size = reply_literal(ws, "d14:failure reason80:Your client forgot to send your torrent's info_hash. Please upgrade your client.e");
+
+  if (OT_PEERFLAG(&ws->peer) & PEER_FLAG_STOPPED)
+    ws->reply_size = remove_peer_from_torrent(FLAG_TCP, ws);
+  else
+    ws->reply_size = add_peer_to_torrent_and_return_peers(FLAG_TCP, ws, numwant);
+
+  stats_issue_event(ws, EVENT_ANNOUNCE, FLAG_TCP, ws->reply_size);
+  return ws->reply_size;
+}
+
+ssize_t http_handle_request(const int64_t sock, struct ot_workstruct *ws) {
+  ssize_t reply_off, len;
+  char   *read_ptr = ws->request, *write_ptr;
+
+#ifdef _DEBUG_HTTPERROR
+  reply_off = ws->request_size;
+  if (ws->request_size >= G_DEBUGBUF_SIZE)
+    reply_off = G_DEBUGBUF_SIZE - 1;
+  memcpy(ws->debugbuf, ws->request, reply_off);
+  ws->debugbuf[reply_off] = 0;
+#endif
+
+  /* Tell subroutines where to put reply data */
+  ws->reply = ws->outbuf + SUCCESS_HTTP_HEADER_LENGTH;
+
+  /* Find out if the client wants to keep this connection alive, before any
+     subroutine gets to answer: an error reply finishes with the connection
+     on its way out, and ws outlives the connection it was serving */
+  ws->keep_alive = 0;
+#ifdef WANT_KEEPALIVE
+  if ((write_ptr = http_header(ws->request, ws->header_size, "connection")) && (*write_ptr == 'K' || *write_ptr == 'k'))
+    ws->keep_alive = 1;
+#endif
+  {
+    struct http_data *connection = fdstate_cookie(sock);
+    if (connection) {
+      if (ws->keep_alive)
+        connection->flag |= STRUCT_HTTP_FLAG_KEEPALIVE;
+      else
+        connection->flag &= ~STRUCT_HTTP_FLAG_KEEPALIVE;
+    }
+  }
+
+  /* This one implicitely tests strlen < 5, too -- remember, it is \n terminated */
+  if (memcmp(read_ptr, "GET /", 5))
+    HTTPERROR_400;
+
+  /* Skip leading '/' */
+  for (read_ptr += 4; *read_ptr == '/'; ++read_ptr)
+    ;
+
+  /* Try to parse the request.
+     In reality we abandoned requiring the url to be correct. This now
+     only decodes url encoded characters, we check for announces and
+     scrapes by looking for "a*" or "sc" */
+  len = urlencoded_parse(&read_ptr, write_ptr = read_ptr, SCAN_PATH);
+
+  /* If parsing returned an error, leave with not found */
+  if (g_redirecturl && (len == -2))
+    HTTPERROR_302;
+  if (len <= 0)
+    HTTPERROR_404;
+
+  /* This is the hardcore match for announce*/
+  if ((*write_ptr == 'a') || (*write_ptr == '?'))
+    http_handle_announce(sock, ws, read_ptr);
+#ifdef WANT_FULLSCRAPE
+  else if (!memcmp(write_ptr, "scrape HTTP/", 12))
+    http_handle_fullscrape(sock, ws);
+#endif
+  /* This is the hardcore match for scrape */
+  else if (!memcmp(write_ptr, "sc", 2))
+    http_handle_scrape(sock, ws, read_ptr);
+  /* All the rest is matched the standard way */
+  else if (len == g_stats_path_len && !memcmp(write_ptr, g_stats_path, len))
+    http_handle_stats(sock, ws, read_ptr);
+  else
+    HTTPERROR_404;
+
+  /* If routines handled sending themselves, just return */
+  if (ws->reply_size == -2)
+    return 0;
+  /* If routine failed, let http error take over */
+  if (ws->reply_size <= 0)
+    HTTPERROR_500;
+
+  /* This one is rather ugly, so I take you step by step through it.
+
+     1. In order to avoid having two buffers, one for header and one for content, we allow all above functions from trackerlogic to
+     write to a fixed location, leaving SUCCESS_HTTP_HEADER_LENGTH bytes in our work buffer, which is enough for the static string
+     plus dynamic space needed to expand our Content-Length value. We reserve SUCCESS_HTTP_SIZE_OFF for its expansion and calculate
+     the space NOT needed to expand in reply_off
+  */
+  reply_off       = SUCCESS_HTTP_SIZE_OFF - snprintf(ws->outbuf, 0, "%zd", ws->reply_size);
+  ws->reply       = ws->outbuf + reply_off;
+
+  /* 2. Now we write the header so that its terminating '\0' lands exactly one byte before the content starts. The bound is the
+     space step 1 reserved, so the '\0' falls where step 3 expects it. Complete packet size is increased by size of header plus
+     one byte '\n', we will copy over '\0' in next step */
+  ws->reply_size += 1 + snprintf(ws->reply, (size_t)(SUCCESS_HTTP_HEADER_LENGTH - reply_off),
+                                 "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\nContent-Length: %zd\r\n\r", ws->reply_size);
+
+  /* 3. Finally we join both blocks neatly */
+  ws->outbuf[SUCCESS_HTTP_HEADER_LENGTH - 1] = '\n';
+
+  http_senddata(sock, ws);
+  return ws->reply_size;
+}
diff --git a/src/ot_http.h b/src/ot_http.h
new file mode 100644
index 0000000..fb56c64
--- /dev/null
+++ b/src/ot_http.h
@@ -0,0 +1,53 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_HTTP_H__
+#define OT_HTTP_H__
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include "ot_batch.h"
+#include "ot_event.h"
+#include "ot_buf.h"
+#include "trackerlogic.h"
+
+typedef enum {
+  STRUCT_HTTP_FLAG_WAITINGFORTASK      = 1,
+  STRUCT_HTTP_FLAG_GZIP                = 2,
+  STRUCT_HTTP_FLAG_BZIP2               = 4,
+  STRUCT_HTTP_FLAG_ZSTD                = 8,
+  STRUCT_HTTP_FLAG_CHUNKED             = 16,
+  STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER = 32,
+  STRUCT_HTTP_FLAG_KEEPALIVE           = 64,
+  STRUCT_HTTP_FLAG_ONSTACK             = 128
+} STRUCT_HTTP_FLAG;
+
+struct http_data {
+  ot_buf           request;
+  int              interest; /* EVENT_IN and EVENT_OUT as asked for */
+  ot_batch        *batch;
+  ot_ip6           ip;
+  STRUCT_HTTP_FLAG flag;
+};
+
+/* What this connection is waiting for: EVENT_IN, EVENT_OUT, or nothing */
+void           http_interest_set(const int64_t s, struct http_data *cookie, int what);
+
+/* Close a connection and release everything that belongs to it */
+void           http_close(const int64_t s);
+
+/* Promote a stack cookie to a heap one, for persistence and for handing it
+   over to the event loop or to another thread. Does nothing to one that is
+   already on the heap. Returns the connection's state, or NULL. */
+struct http_data *http_adopt(const int64_t s);
+
+ssize_t        http_handle_request(const int64_t s, struct ot_workstruct *ws);
+ssize_t        http_sendiovecdata(const int64_t s, struct ot_workstruct *ws, size_t iovec_entries, struct iovec *iovector, int is_partial);
+ssize_t        http_issue_error(const int64_t s, struct ot_workstruct *ws, int code);
+
+extern const char *g_stats_path;
+extern ssize_t g_stats_path_len;
+
+#endif
diff --git a/src/ot_iovec.c b/src/ot_iovec.c
new file mode 100644
index 0000000..328f160
--- /dev/null
+++ b/src/ot_iovec.c
@@ -0,0 +1,87 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdlib.h>
+#include <sys/uio.h>
+
+/* Opentracker */
+#include "ot_iovec.h"
+
+void *iovec_new_chunk(size_t *iovec_entries, struct iovec **iovector, size_t new_alloc) {
+  void         *new_data;
+  size_t        new_entries = 1 + *iovec_entries;
+  struct iovec *new_vec     = realloc(*iovector, new_entries * sizeof(struct iovec));
+
+  if (!new_vec)
+    return NULL;
+
+  *iovector  = new_vec;
+
+  /* Only allocate after we have a place to store the pointer */
+  new_data = malloc(new_alloc);
+  if (!new_data)
+    return NULL;
+
+  new_vec[new_entries - 1].iov_base = new_data;
+  new_vec[new_entries - 1].iov_len  = new_alloc;
+
+  ++*iovec_entries;
+  return new_data;
+}
+
+void *iovec_append(size_t *iovec_entries, struct iovec **iovector, struct iovec *append_iovector) {
+  size_t        new_entries = *iovec_entries + 1;
+  struct iovec *new_vec     = realloc(*iovector, new_entries * sizeof(struct iovec));
+  if (!new_vec)
+    return NULL;
+
+  /* Take over data from appended iovec */
+  new_vec[*iovec_entries].iov_base = append_iovector->iov_base;
+  new_vec[*iovec_entries].iov_len  = append_iovector->iov_len;
+
+  append_iovector->iov_base        = NULL;
+  append_iovector->iov_len         = 0;
+
+  *iovector                        = new_vec;
+  *iovec_entries                   = new_entries;
+
+  return new_vec;
+}
+
+void iovec_free(size_t *iovec_entries, struct iovec **iovector) {
+  size_t i;
+  for (i = 0; i < *iovec_entries; ++i)
+    free(((*iovector)[i]).iov_base);
+  free(*iovector);
+  *iovector      = NULL;
+  *iovec_entries = 0;
+}
+
+void iovec_trim_last(size_t *iovec_entries, struct iovec **iovector, void *last_ptr) {
+  if (*iovec_entries) {
+    char  *base      = (char *)((*iovector)[*iovec_entries - 1]).iov_base;
+    size_t new_alloc = ((char *)last_ptr) - base;
+
+    ((*iovector)[*iovec_entries - 1]).iov_base = realloc(base, new_alloc);
+    ((*iovector)[*iovec_entries - 1]).iov_len  = new_alloc;
+  }
+}
+
+void *iovec_next_chunk(size_t *iovec_entries, struct iovec **iovector, void *last_ptr, size_t new_alloc) {
+  void *new_data;
+
+  iovec_trim_last(iovec_entries, iovector, last_ptr);
+
+  if (!(new_data = iovec_new_chunk(iovec_entries, iovector, new_alloc)))
+    iovec_free(iovec_entries, iovector);
+
+  return new_data;
+}
+
+size_t iovec_length(const size_t *iovec_entries, const struct iovec **iovector) {
+  size_t i, length = 0;
+  for (i = 0; i < *iovec_entries; ++i)
+    length += ((*iovector)[i]).iov_len;
+  return length;
+}
diff --git a/src/ot_iovec.h b/src/ot_iovec.h
new file mode 100644
index 0000000..4a8abbb
--- /dev/null
+++ b/src/ot_iovec.h
@@ -0,0 +1,18 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_IOVEC_H__
+#define OT_IOVEC_H__
+
+#include <sys/uio.h>
+
+void  *iovec_new_chunk(size_t *iovec_entries, struct iovec **iovector, size_t new_alloc);
+void  *iovec_append(size_t *iovec_entries, struct iovec **iovector, struct iovec *append_iovector);
+void   iovec_trim_last(size_t *iovec_entries, struct iovec **iovector, void *last_ptr);
+void   iovec_free(size_t *iovec_entries, struct iovec **iovector);
+
+size_t iovec_length(const size_t *iovec_entries, const struct iovec **iovector);
+
+void  *iovec_next_chunk(size_t *iovec_entries, struct iovec **iovector, void *last_ptr, size_t new_alloc);
+
+#endif
diff --git a/src/ot_ip.c b/src/ot_ip.c
new file mode 100644
index 0000000..9c76290
--- /dev/null
+++ b/src/ot_ip.c
@@ -0,0 +1,199 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdint.h>
+#include <string.h>
+
+/* Opentracker */
+#include "ot_hex.h"
+#include "ot_ip.h"
+
+const char ip_v4mapped_prefix[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff};
+
+/* The dotted quad is only ever reached through the v4 mapped form, so both
+   halves of it stay in here */
+
+static size_t ip4_format(char *dest, const uint8_t *ip) {
+  char *d = dest;
+  int   i;
+
+  for (i = 0; i < 4; ++i) {
+    unsigned int octet = ip[i];
+
+    if (i)
+      *d++ = '.';
+    if (octet >= 100)
+      *d++ = (char)('0' + octet / 100);
+    if (octet >= 10)
+      *d++ = (char)('0' + (octet / 10) % 10);
+    *d++ = (char)('0' + octet % 10);
+  }
+
+  return (size_t)(d - dest);
+}
+
+static size_t ip4_scan(const char *src, uint8_t ip[4]) {
+  uint8_t     octets[4];
+  const char *s = src;
+  int         i;
+
+  for (i = 0; i < 4; ++i) {
+    unsigned int value  = 0;
+    int          digits = 0;
+
+    if (i && *s++ != '.')
+      return 0;
+
+    /* Leading zeros are tolerated, a value beyond one octet is not */
+    while (*s >= '0' && *s <= '9' && digits < 4) {
+      value = value * 10 + (unsigned int)(*s++ - '0');
+      ++digits;
+    }
+    if (!digits || value > 255)
+      return 0;
+
+    octets[i] = (uint8_t)value;
+  }
+
+  memcpy(ip, octets, sizeof(octets));
+  return (size_t)(s - src);
+}
+
+static unsigned int group_at(const char *ip, int n) { return ((unsigned int)(uint8_t)ip[2 * n] << 8) | (uint8_t)ip[2 * n + 1]; }
+
+size_t ip_format(char *dest, const ot_ip6 ip) {
+  static const char hexdigit[] = "0123456789abcdef";
+  char             *d          = dest;
+  int               best_start = 0, best_len = 0, i = 0;
+
+  if (ip_is_v4mapped(ip))
+    return ip4_format(dest, (const uint8_t *)ip + sizeof(ip_v4mapped_prefix));
+
+  /* RFC 5952 4.2: the longest run of zero groups becomes "::", never a run
+     of one, and the first of two equal runs wins */
+  while (i < 8) {
+    int j = i;
+
+    if (group_at(ip, i)) {
+      ++i;
+      continue;
+    }
+    while (j < 8 && !group_at(ip, j))
+      ++j;
+    if (j - i > best_len) {
+      best_len   = j - i;
+      best_start = i;
+    }
+    i = j;
+  }
+  if (best_len < 2)
+    best_len = 0;
+
+  for (i = 0; i < 8; ++i) {
+    unsigned int group;
+    int          shift = 12;
+
+    if (best_len && i == best_start) {
+      *d++ = ':';
+      if (i + best_len == 8)
+        *d++ = ':'; /* nothing follows, so close the run */
+      i += best_len - 1;
+      continue;
+    }
+
+    if (i)
+      *d++ = ':';
+
+    group = group_at(ip, i);
+    while (shift && !(group >> shift))
+      shift -= 4; /* RFC 5952 4.1: no leading zeros */
+    for (;; shift -= 4) {
+      *d++ = hexdigit[(group >> shift) & 15];
+      if (!shift)
+        break;
+    }
+  }
+
+  return (size_t)(d - dest);
+}
+
+size_t ip_parse(const char *src, ot_ip6 ip) {
+  uint8_t     prefix[16], suffix[16];
+  size_t      prefixlen = 0, suffixlen = 0;
+  const char *s          = src;
+  int         have_gap   = 0;
+  int         need_colon = 0;
+
+  /* A plain IPv4 address is an address too, stored v4 mapped */
+  {
+    size_t consumed = ip4_scan(src, prefix);
+    if (consumed) {
+      memcpy(ip, ip_v4mapped_prefix, sizeof(ip_v4mapped_prefix));
+      memcpy(ip + sizeof(ip_v4mapped_prefix), prefix, 4);
+      return consumed;
+    }
+  }
+
+  for (;;) {
+    unsigned int value  = 0;
+    int          digits = 0, nibble;
+    uint8_t     *into   = have_gap ? suffix : prefix;
+    size_t      *fill   = have_gap ? &suffixlen : &prefixlen;
+
+    /* RFC 4291 2.2: one run of zero groups may be written "::" */
+    if (s[0] == ':' && s[1] == ':') {
+      if (have_gap)
+        return 0;
+      have_gap   = 1;
+      need_colon = 0;
+      s += 2;
+      continue;
+    }
+
+    if (need_colon) {
+      if (*s != ':')
+        break;
+      ++s;
+    }
+
+    /* RFC 4291 2.2 form 3: the final two groups may be a dotted quad */
+    if (prefixlen + suffixlen + 4 <= 16) {
+      size_t consumed = ip4_scan(s, into + *fill);
+      if (consumed) {
+        *fill += 4;
+        s += consumed;
+        break;
+      }
+    }
+
+    while (digits < 4 && (nibble = hex_value(*s)) >= 0) {
+      value = value * 16 + (unsigned int)nibble;
+      ++digits;
+      ++s;
+    }
+    if (!digits) {
+      if (need_colon)
+        --s; /* leave the separator we ate for the caller */
+      break;
+    }
+
+    if (prefixlen + suffixlen + 2 > 16)
+      return 0;
+
+    into[(*fill)++] = (uint8_t)(value >> 8);
+    into[(*fill)++] = (uint8_t)value;
+    need_colon      = 1;
+  }
+
+  if (!prefixlen && !suffixlen && !have_gap)
+    return 0;
+  if (!have_gap && prefixlen + suffixlen != 16)
+    return 0; /* without "::" every group has to be spelled out */
+
+  memset(ip, 0, 16);
+  memcpy(ip, prefix, prefixlen);
+  memcpy(ip + 16 - suffixlen, suffix, suffixlen);
+
+  return (size_t)(s - src);
+}
diff --git a/src/ot_ip.h b/src/ot_ip.h
new file mode 100644
index 0000000..533403e
--- /dev/null
+++ b/src/ot_ip.h
@@ -0,0 +1,31 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_IP_H__
+#define OT_IP_H__
+
+#include <stddef.h>
+#include <string.h>
+
+#include "trackerlogic.h"
+
+/* opentracker holds every address as sixteen bytes, writing IPv4 as the v4
+   mapped form of RFC 4291 section 2.5.5.2. */
+extern const char ip_v4mapped_prefix[12];
+
+static inline int ip_is_v4mapped(const void *ip) { return !memcmp(ip, ip_v4mapped_prefix, sizeof(ip_v4mapped_prefix)); }
+
+/* Read an address and return how many characters it took, or zero if src
+   does not start with one. A plain IPv4 address is accepted and stored in
+   its v4 mapped form.
+
+   The count lets the caller carry on where the address ended, which is how
+   "address:port" and "address/bits" are read. */
+size_t ip_parse(const char *src, ot_ip6 ip);
+
+/* Write an address and return how many characters it took. Nothing is
+   terminated, so a caller may keep appending. A v4 mapped address is written
+   as the plain dotted quad rather than "::ffff:1.2.3.4".  */
+size_t ip_format(char *dest, const ot_ip6 ip);
+
+#endif
diff --git a/src/ot_livesync.c b/src/ot_livesync.c
new file mode 100644
index 0000000..083fe1a
--- /dev/null
+++ b/src/ot_livesync.c
@@ -0,0 +1,241 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+ It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_ip.h"
+#include "ot_socket.h"
+#include "ot_livesync.h"
+#include "ot_mutex.h"
+#include "ot_stats.h"
+#include "trackerlogic.h"
+
+#ifdef WANT_SYNC_LIVE
+
+ot_ip6 groupip_1 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 224, 0, 23, 5};
+
+#define LIVESYNC_INCOMING_BUFFSIZE        (256 * 256)
+
+#define LIVESYNC_OUTGOING_BUFFSIZE_PEERS  1480
+#define LIVESYNC_OUTGOING_WATERMARK_PEERS (sizeof(ot_peer) + sizeof(ot_hash))
+
+#define LIVESYNC_MAXDELAY                 15 /* seconds */
+
+enum { OT_SYNC_PEER4, OT_SYNC_PEER6 };
+
+/* Forward declaration */
+static void           *livesync_worker(void *args);
+
+/* For incoming packets */
+static int             g_socket_in    = -1;
+
+/* For outgoing packets */
+static int             g_socket_out   = -1;
+
+static pthread_mutex_t g_outbuf_mutex = PTHREAD_MUTEX_INITIALIZER;
+typedef struct {
+  uint8_t data[LIVESYNC_OUTGOING_BUFFSIZE_PEERS];
+  size_t  fill;
+  ot_time next_packet_time;
+} sync_buffer;
+
+static sync_buffer g_v6_buf;
+static sync_buffer g_v4_buf;
+
+static pthread_t   thread_id;
+static int         thread_started;
+static _Atomic int thread_left;
+void livesync_init(void) {
+  uint32_t packet_type6 = htonl(OT_SYNC_PEER6);
+  uint32_t packet_type4 = htonl(OT_SYNC_PEER4);
+
+  if (g_socket_in == -1)
+    exerr("No socket address for live sync specified.");
+
+  /* Prepare outgoing peers buffer */
+  memcpy(g_v6_buf.data, &g_tracker_id, sizeof(g_tracker_id));
+  memcpy(g_v4_buf.data, &g_tracker_id, sizeof(g_tracker_id));
+
+  memcpy(g_v6_buf.data + sizeof(g_tracker_id), &packet_type6, sizeof(packet_type6));
+  memcpy(g_v4_buf.data + sizeof(g_tracker_id), &packet_type4, sizeof(packet_type4));
+
+  g_v6_buf.fill             = sizeof(g_tracker_id) + sizeof(uint32_t);
+  g_v4_buf.fill             = sizeof(g_tracker_id) + sizeof(uint32_t);
+
+  g_v6_buf.next_packet_time = time_future_seconds(LIVESYNC_MAXDELAY);
+  g_v4_buf.next_packet_time = time_future_seconds(LIVESYNC_MAXDELAY);
+
+  thread_started = !pthread_create(&thread_id, NULL, livesync_worker, NULL);
+}
+
+void livesync_deinit(void) {
+  if (thread_started) {
+    /* Repeats so it interrupts a read already under way */
+    while (!atomic_load(&thread_left)) {
+      pthread_kill(thread_id, OT_SIGNAL_WAKE);
+      usleep(1000);
+    }
+    pthread_join(thread_id, NULL);
+    thread_started = 0;
+  }
+
+  if (g_socket_in != -1)
+    close(g_socket_in);
+  if (g_socket_out != -1)
+    close(g_socket_out);
+}
+
+void livesync_bind_mcast(ot_ip6 ip, uint16_t port) {
+  if (!ip_is_v4mapped(ip))
+    exerr("v6 mcast support not yet available.");
+
+  if (g_socket_in != -1)
+    exerr("Error: Livesync listen ip specified twice.");
+
+  if ((g_socket_in = socket_mcast_join(groupip_1, ip, port)) == -1)
+    exerr("Error: Cant bind live sync incoming socket.");
+
+  if ((g_socket_out = socket_mcast_bind(ip, port, 0)) == -1)
+    exerr("Error: Cant bind live sync outgoing socket.");
+}
+
+/* Caller MUST hold g_outbuf_mutex. Returns with g_outbuf_mutex unlocked */
+static void livesync_issue_peersync(sync_buffer *buf) {
+  char   mycopy[LIVESYNC_OUTGOING_BUFFSIZE_PEERS];
+  size_t fill = buf->fill;
+
+  memcpy(mycopy, buf->data, fill);
+  buf->fill             = sizeof(g_tracker_id) + sizeof(uint32_t);
+  buf->next_packet_time = time_future_seconds(LIVESYNC_MAXDELAY);
+
+  /* From now this thread has a local copy of the buffer and
+     has modified the protected element */
+  pthread_mutex_unlock(&g_outbuf_mutex);
+
+  socket_mcast_send(g_socket_out, mycopy, fill, groupip_1, LIVESYNC_PORT);
+}
+
+static void livesync_handle_peersync(struct ot_workstruct *ws, size_t peer_size) {
+  size_t off = sizeof(g_tracker_id) + sizeof(uint32_t);
+
+  /* Prepare peer record for v4mapped expansion */
+  if (peer_size == OT_PEER_SIZE4)
+    memcpy(&ws->peer, ip_v4mapped_prefix, sizeof(ip_v4mapped_prefix));
+
+  /* Now basic sanity checks have been done on the live sync packet
+     We might add more testing and logging. */
+  while ((ssize_t)(off + sizeof(ot_hash) + peer_size) <= ws->request_size) {
+    char *peer_ip = ws->request + off + sizeof(ot_hash);
+    if (peer_size == OT_PEER_SIZE4)
+        memcpy(&ws->peer[0] + sizeof(ip_v4mapped_prefix), peer_ip, peer_size);
+    else
+        memcpy(&ws->peer, peer_ip, peer_size);
+    ws->hash = (ot_hash *)(ws->request + off);
+
+    if (!g_opentracker_running)
+      return;
+
+    if (OT_PEERFLAG(ws->peer) & PEER_FLAG_STOPPED)
+      remove_peer_from_torrent(FLAG_MCA, ws);
+    else
+      add_peer_to_torrent_and_return_peers(FLAG_MCA, ws, /* amount = */ 0);
+
+    off += sizeof(ot_hash) + peer_size;
+  }
+
+  stats_issue_event(ws, EVENT_SYNC, 0, (ws->request_size - sizeof(g_tracker_id) - sizeof(uint32_t)) / ((ssize_t)sizeof(ot_hash) + peer_size));
+}
+
+/* Tickle the live sync module from time to time, so no events get
+   stuck when there's not enough traffic to fill udp packets fast
+   enough */
+void livesync_ticker(void) {
+  /* livesync_issue_peersync sets g_next_packet_time */
+  pthread_mutex_lock(&g_outbuf_mutex);
+  if (time_now_seconds() > g_v6_buf.next_packet_time && g_v6_buf.fill > sizeof(g_tracker_id) + sizeof(uint32_t))
+    livesync_issue_peersync(&g_v6_buf);
+  else
+    pthread_mutex_unlock(&g_outbuf_mutex);
+
+  pthread_mutex_lock(&g_outbuf_mutex);
+  if (time_now_seconds() > g_v4_buf.next_packet_time && g_v4_buf.fill > sizeof(g_tracker_id) + sizeof(uint32_t))
+    livesync_issue_peersync(&g_v4_buf);
+  else
+    pthread_mutex_unlock(&g_outbuf_mutex);
+}
+
+/* Inform live sync about whats going on. */
+void livesync_tell(struct ot_workstruct *ws) {
+  size_t       peer_size; /* initialized in next line */
+  ot_peer     *peer_src = peer_from_peer6(&ws->peer, &peer_size);
+  sync_buffer *dest_buf = peer_size == OT_PEER_SIZE6 ? &g_v6_buf : &g_v4_buf;
+
+  pthread_mutex_lock(&g_outbuf_mutex);
+
+  memcpy(dest_buf->data + dest_buf->fill, ws->hash, sizeof(ot_hash));
+  dest_buf->fill += sizeof(ot_hash);
+
+  memcpy(dest_buf->data + dest_buf->fill, peer_src, peer_size);
+  dest_buf->fill += peer_size;
+
+  if (dest_buf->fill >= LIVESYNC_OUTGOING_BUFFSIZE_PEERS - LIVESYNC_OUTGOING_WATERMARK_PEERS)
+    livesync_issue_peersync(dest_buf);
+  else
+    pthread_mutex_unlock(&g_outbuf_mutex);
+}
+
+static void *livesync_worker(void *args) {
+  struct ot_workstruct ws;
+  ot_ip6               in_ip;
+  uint16_t             in_port;
+
+  (void)args;
+
+  /* Initialize our "thread local storage" */
+  ws.inbuf = ws.request = malloc(LIVESYNC_INCOMING_BUFFSIZE);
+  ws.outbuf = ws.reply = 0;
+
+  while (g_opentracker_running) {
+    uint32_t packet_type;
+
+    ws.request_size = socket_recv(g_socket_in, ws.inbuf, LIVESYNC_INCOMING_BUFFSIZE, in_ip, &in_port);
+
+    /* Expect at least tracker id and packet type */
+    if (ws.request_size <= (ssize_t)(sizeof(g_tracker_id) + sizeof(uint32_t)))
+      continue;
+    if (!accesslist_is_blessed(in_ip, OT_PERMISSION_MAY_LIVESYNC))
+      continue;
+    if (!memcmp(ws.inbuf, &g_tracker_id, sizeof(g_tracker_id))) {
+      /* TODO: log packet coming from ourselves */
+      continue;
+    }
+
+    memcpy(&packet_type, ws.inbuf + sizeof(g_tracker_id), sizeof(packet_type));
+
+    switch (ntohl(packet_type)) {
+    case OT_SYNC_PEER6:
+      livesync_handle_peersync(&ws, OT_PEER_SIZE6);
+      break;
+    case OT_SYNC_PEER4:
+      livesync_handle_peersync(&ws, OT_PEER_SIZE4);
+      break;
+    default:
+      break;
+    }
+  }
+
+  free(ws.inbuf);
+  atomic_store(&thread_left, 1);
+  return NULL;
+}
+
+#endif
diff --git a/src/ot_livesync.h b/src/ot_livesync.h
new file mode 100644
index 0000000..4bd3af0
--- /dev/null
+++ b/src/ot_livesync.h
@@ -0,0 +1,75 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+ It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_LIVESYNC_H__
+#define OT_LIVESYNC_H__
+
+#include "trackerlogic.h"
+
+/*
+  Syncing is done as udp packets in the multicast domain 224.0.42.5 port 9696
+
+  Each tracker should join the multicast group and send its live sync packets
+  to that group, using a ttl of 1
+
+  Format of all sync packets is straight forward, packet type determines
+  which kind of packet this is:
+
+    0x0000 0x04 id of tracker instance
+    0x0004 0x04 packet type
+
+                             ########
+ ######## PEER SYNC PROTOCOL ########
+ ########
+
+  Each tracker instance accumulates announce requests until its buffer is
+  full or a timeout is reached. Then it broadcasts its live sync packer:
+
+  packet type SYNC_LIVE4
+  [ 0x0008 0x14 info_hash
+    0x001c 0x04 peer's ipv4 address
+    0x0020 0x02 peer's port
+    0x0024 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
+  ]*
+
+  packet type SYNC_LIVE6
+  [ 0x0008 0x14 info_hash
+    0x001c 0x10 peer's ipv6 address
+    0x002c 0x02 peer's port
+    0x002e 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
+  ]*
+*/
+
+#ifdef WANT_SYNC_LIVE
+
+#define LIVESYNC_PORT 9696
+
+void livesync_init(void);
+void livesync_deinit(void);
+
+/* Join multicast group for listening and create sending socket */
+void livesync_bind_mcast(ot_ip6 ip, uint16_t port);
+
+/* Inform live sync about whats going on. */
+void livesync_tell(struct ot_workstruct *ws);
+
+/* Tickle the live sync module from time to time, so no events get
+   stuck when there's not enough traffic to fill udp packets fast
+   enough */
+void livesync_ticker(void);
+
+/* Handle an incoming live sync packet */
+void handle_livesync(const int64_t sock);
+
+#else
+
+/* If no syncing is required, save calling code from #ifdef
+   constructions */
+#define livesync_deinit()
+#define livesync_init()
+#define livesync_ticker()
+#define handle_livesync(a)
+
+#endif
+
+#endif
diff --git a/src/ot_mutex.c b/src/ot_mutex.c
new file mode 100644
index 0000000..884b74c
--- /dev/null
+++ b/src/ot_mutex.c
@@ -0,0 +1,70 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/uio.h>
+
+
+/* Opentracker */
+#include "ot_iovec.h"
+#include "ot_mutex.h"
+#include "ot_stats.h"
+#include "trackerlogic.h"
+
+/* #define MTX_DBG( STRING ) fprintf( stderr, STRING ) */
+#define MTX_DBG(STRING)
+
+/* Our global all torrents list */
+static ot_vector       all_torrents[OT_BUCKET_COUNT];
+static pthread_mutex_t bucket_mutex[OT_BUCKET_COUNT];
+/* Every bucket's unlock adjusts this, and a bucket lock only keeps other
+   threads out of that one bucket, so the counter needs its own protection */
+static _Atomic size_t  g_torrent_count;
+
+ot_vector *mutex_bucket_lock(int bucket) {
+  pthread_mutex_lock(bucket_mutex + bucket);
+  return all_torrents + bucket;
+}
+
+/* Torrents are spread over buckets by the first four bytes of their info_hash,
+   which may sit at any alignment, hence the memcpy */
+static int bucket_from_hash(ot_hash const hash) {
+  uint32_t bucket;
+  memcpy(&bucket, hash, sizeof(bucket));
+  return ntohl(bucket) >> OT_BUCKET_COUNT_SHIFT;
+}
+
+ot_vector *mutex_bucket_lock_by_hash(ot_hash const hash) { return mutex_bucket_lock(bucket_from_hash(hash)); }
+
+void mutex_bucket_unlock(int bucket, int delta_torrentcount) {
+  pthread_mutex_unlock(bucket_mutex + bucket);
+  if (delta_torrentcount)
+    atomic_fetch_add_explicit(&g_torrent_count, (size_t)delta_torrentcount, memory_order_relaxed);
+}
+
+void mutex_bucket_unlock_by_hash(ot_hash const hash, int delta_torrentcount) {
+  mutex_bucket_unlock(bucket_from_hash(hash), delta_torrentcount);
+}
+
+size_t mutex_get_torrent_count(void) { return atomic_load_explicit(&g_torrent_count, memory_order_relaxed); }
+
+void mutex_init(void) {
+  size_t i;
+  for (i = 0; i < OT_BUCKET_COUNT; ++i)
+    pthread_mutex_init(bucket_mutex + i, NULL);
+  memset(all_torrents, 0, sizeof(all_torrents));
+}
+
+void mutex_deinit(void) {
+  size_t i;
+  for (i = 0; i < OT_BUCKET_COUNT; ++i)
+    pthread_mutex_destroy(bucket_mutex + i);
+  memset(all_torrents, 0, sizeof(all_torrents));
+}
diff --git a/src/ot_mutex.h b/src/ot_mutex.h
new file mode 100644
index 0000000..d7ded92
--- /dev/null
+++ b/src/ot_mutex.h
@@ -0,0 +1,21 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_MUTEX_H__
+#define OT_MUTEX_H__
+
+#include <sys/uio.h>
+#include "trackerlogic.h"
+
+void       mutex_init(void);
+void       mutex_deinit(void);
+
+ot_vector *mutex_bucket_lock(int bucket);
+ot_vector *mutex_bucket_lock_by_hash(ot_hash const hash);
+
+void       mutex_bucket_unlock(int bucket, int delta_torrentcount);
+void       mutex_bucket_unlock_by_hash(ot_hash const hash, int delta_torrentcount);
+
+size_t     mutex_get_torrent_count(void);
+
+#endif
diff --git a/src/ot_random.c b/src/ot_random.c
new file mode 100644
index 0000000..43f91bb
--- /dev/null
+++ b/src/ot_random.c
@@ -0,0 +1,51 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Opentracker */
+#include "ot_random.h"
+
+#ifdef WANT_INSECURE_RANDOM_FALLBACK
+
+#warning WANT_INSECURE_RANDOM_FALLBACK builds without arc4random. UDP connection ids become predictable and announces can be forged. Do not ship this.
+
+#include <time.h>
+
+void random_init(void) {
+#ifdef WANT_DEV_RANDOM
+  srandomdev();
+#else
+  srandom(time(NULL));
+#endif
+}
+
+/* random() yields 31 bits, so one draw can never set the top bit. Combine
+   two of them rather than hand out a value that is quietly half as wide as
+   its type claims. */
+uint32_t random_uint32(void) { return ((uint32_t)random() << 16) ^ (uint32_t)random(); }
+
+void     random_bytes(void *buf, size_t len) {
+  uint8_t *out = buf;
+  /* random() leaves the top bit clear and its lowest bits are the weakest,
+     so take a byte from the middle of each draw */
+  while (len--)
+       *out++ = (uint8_t)(random() >> 8);
+}
+
+#else
+
+#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__) && !defined(__DragonFly__) && !defined(__APPLE__) &&                                     \
+    !(defined(__GLIBC__) && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 36)))
+#include <bsd/stdlib.h>
+#endif
+
+void     random_init(void) {}
+
+uint32_t random_uint32(void) { return arc4random(); }
+
+void     random_bytes(void *buf, size_t len) { arc4random_buf(buf, len); }
+
+#endif
diff --git a/src/ot_random.h b/src/ot_random.h
new file mode 100644
index 0000000..c2d0387
--- /dev/null
+++ b/src/ot_random.h
@@ -0,0 +1,17 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_RANDOM_H__
+#define OT_RANDOM_H__
+
+#include <stddef.h>
+#include <stdint.h>
+
+/* Seed whatever generator the build settled on. A no-op when backed by
+   arc4random, which seeds itself from the kernel. */
+void     random_init(void);
+
+uint32_t random_uint32(void);
+void     random_bytes(void *buf, size_t len);
+
+#endif
diff --git a/src/ot_rijndael.c b/src/ot_rijndael.c
new file mode 100644
index 0000000..3f36bde
--- /dev/null
+++ b/src/ot_rijndael.c
@@ -0,0 +1,488 @@
+/**
+ * rijndael-alg-fst.c
+ *
+ * @version 3.0 (December 2000)
+ *
+ * Optimised ANSI C code for the Rijndael cipher (now AES)
+ *
+ * @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
+ * @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
+ * @author Paulo Barreto <paulo.barreto@terra.com.br>
+ *
+ * This code is hereby placed in the public domain.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "ot_rijndael.h"
+
+static const uint32_t Te0[256] = {
+    0xc66363a5U, 0xf87c7c84U, 0xee777799U, 0xf67b7b8dU,
+    0xfff2f20dU, 0xd66b6bbdU, 0xde6f6fb1U, 0x91c5c554U,
+    0x60303050U, 0x02010103U, 0xce6767a9U, 0x562b2b7dU,
+    0xe7fefe19U, 0xb5d7d762U, 0x4dababe6U, 0xec76769aU,
+    0x8fcaca45U, 0x1f82829dU, 0x89c9c940U, 0xfa7d7d87U,
+    0xeffafa15U, 0xb25959ebU, 0x8e4747c9U, 0xfbf0f00bU,
+    0x41adadecU, 0xb3d4d467U, 0x5fa2a2fdU, 0x45afafeaU,
+    0x239c9cbfU, 0x53a4a4f7U, 0xe4727296U, 0x9bc0c05bU,
+    0x75b7b7c2U, 0xe1fdfd1cU, 0x3d9393aeU, 0x4c26266aU,
+    0x6c36365aU, 0x7e3f3f41U, 0xf5f7f702U, 0x83cccc4fU,
+    0x6834345cU, 0x51a5a5f4U, 0xd1e5e534U, 0xf9f1f108U,
+    0xe2717193U, 0xabd8d873U, 0x62313153U, 0x2a15153fU,
+    0x0804040cU, 0x95c7c752U, 0x46232365U, 0x9dc3c35eU,
+    0x30181828U, 0x379696a1U, 0x0a05050fU, 0x2f9a9ab5U,
+    0x0e070709U, 0x24121236U, 0x1b80809bU, 0xdfe2e23dU,
+    0xcdebeb26U, 0x4e272769U, 0x7fb2b2cdU, 0xea75759fU,
+    0x1209091bU, 0x1d83839eU, 0x582c2c74U, 0x341a1a2eU,
+    0x361b1b2dU, 0xdc6e6eb2U, 0xb45a5aeeU, 0x5ba0a0fbU,
+    0xa45252f6U, 0x763b3b4dU, 0xb7d6d661U, 0x7db3b3ceU,
+    0x5229297bU, 0xdde3e33eU, 0x5e2f2f71U, 0x13848497U,
+    0xa65353f5U, 0xb9d1d168U, 0x00000000U, 0xc1eded2cU,
+    0x40202060U, 0xe3fcfc1fU, 0x79b1b1c8U, 0xb65b5bedU,
+    0xd46a6abeU, 0x8dcbcb46U, 0x67bebed9U, 0x7239394bU,
+    0x944a4adeU, 0x984c4cd4U, 0xb05858e8U, 0x85cfcf4aU,
+    0xbbd0d06bU, 0xc5efef2aU, 0x4faaaae5U, 0xedfbfb16U,
+    0x864343c5U, 0x9a4d4dd7U, 0x66333355U, 0x11858594U,
+    0x8a4545cfU, 0xe9f9f910U, 0x04020206U, 0xfe7f7f81U,
+    0xa05050f0U, 0x783c3c44U, 0x259f9fbaU, 0x4ba8a8e3U,
+    0xa25151f3U, 0x5da3a3feU, 0x804040c0U, 0x058f8f8aU,
+    0x3f9292adU, 0x219d9dbcU, 0x70383848U, 0xf1f5f504U,
+    0x63bcbcdfU, 0x77b6b6c1U, 0xafdada75U, 0x42212163U,
+    0x20101030U, 0xe5ffff1aU, 0xfdf3f30eU, 0xbfd2d26dU,
+    0x81cdcd4cU, 0x180c0c14U, 0x26131335U, 0xc3ecec2fU,
+    0xbe5f5fe1U, 0x359797a2U, 0x884444ccU, 0x2e171739U,
+    0x93c4c457U, 0x55a7a7f2U, 0xfc7e7e82U, 0x7a3d3d47U,
+    0xc86464acU, 0xba5d5de7U, 0x3219192bU, 0xe6737395U,
+    0xc06060a0U, 0x19818198U, 0x9e4f4fd1U, 0xa3dcdc7fU,
+    0x44222266U, 0x542a2a7eU, 0x3b9090abU, 0x0b888883U,
+    0x8c4646caU, 0xc7eeee29U, 0x6bb8b8d3U, 0x2814143cU,
+    0xa7dede79U, 0xbc5e5ee2U, 0x160b0b1dU, 0xaddbdb76U,
+    0xdbe0e03bU, 0x64323256U, 0x743a3a4eU, 0x140a0a1eU,
+    0x924949dbU, 0x0c06060aU, 0x4824246cU, 0xb85c5ce4U,
+    0x9fc2c25dU, 0xbdd3d36eU, 0x43acacefU, 0xc46262a6U,
+    0x399191a8U, 0x319595a4U, 0xd3e4e437U, 0xf279798bU,
+    0xd5e7e732U, 0x8bc8c843U, 0x6e373759U, 0xda6d6db7U,
+    0x018d8d8cU, 0xb1d5d564U, 0x9c4e4ed2U, 0x49a9a9e0U,
+    0xd86c6cb4U, 0xac5656faU, 0xf3f4f407U, 0xcfeaea25U,
+    0xca6565afU, 0xf47a7a8eU, 0x47aeaee9U, 0x10080818U,
+    0x6fbabad5U, 0xf0787888U, 0x4a25256fU, 0x5c2e2e72U,
+    0x381c1c24U, 0x57a6a6f1U, 0x73b4b4c7U, 0x97c6c651U,
+    0xcbe8e823U, 0xa1dddd7cU, 0xe874749cU, 0x3e1f1f21U,
+    0x964b4bddU, 0x61bdbddcU, 0x0d8b8b86U, 0x0f8a8a85U,
+    0xe0707090U, 0x7c3e3e42U, 0x71b5b5c4U, 0xcc6666aaU,
+    0x904848d8U, 0x06030305U, 0xf7f6f601U, 0x1c0e0e12U,
+    0xc26161a3U, 0x6a35355fU, 0xae5757f9U, 0x69b9b9d0U,
+    0x17868691U, 0x99c1c158U, 0x3a1d1d27U, 0x279e9eb9U,
+    0xd9e1e138U, 0xebf8f813U, 0x2b9898b3U, 0x22111133U,
+    0xd26969bbU, 0xa9d9d970U, 0x078e8e89U, 0x339494a7U,
+    0x2d9b9bb6U, 0x3c1e1e22U, 0x15878792U, 0xc9e9e920U,
+    0x87cece49U, 0xaa5555ffU, 0x50282878U, 0xa5dfdf7aU,
+    0x038c8c8fU, 0x59a1a1f8U, 0x09898980U, 0x1a0d0d17U,
+    0x65bfbfdaU, 0xd7e6e631U, 0x844242c6U, 0xd06868b8U,
+    0x824141c3U, 0x299999b0U, 0x5a2d2d77U, 0x1e0f0f11U,
+    0x7bb0b0cbU, 0xa85454fcU, 0x6dbbbbd6U, 0x2c16163aU,
+};
+static const uint32_t Te1[256] = {
+    0xa5c66363U, 0x84f87c7cU, 0x99ee7777U, 0x8df67b7bU,
+    0x0dfff2f2U, 0xbdd66b6bU, 0xb1de6f6fU, 0x5491c5c5U,
+    0x50603030U, 0x03020101U, 0xa9ce6767U, 0x7d562b2bU,
+    0x19e7fefeU, 0x62b5d7d7U, 0xe64dababU, 0x9aec7676U,
+    0x458fcacaU, 0x9d1f8282U, 0x4089c9c9U, 0x87fa7d7dU,
+    0x15effafaU, 0xebb25959U, 0xc98e4747U, 0x0bfbf0f0U,
+    0xec41adadU, 0x67b3d4d4U, 0xfd5fa2a2U, 0xea45afafU,
+    0xbf239c9cU, 0xf753a4a4U, 0x96e47272U, 0x5b9bc0c0U,
+    0xc275b7b7U, 0x1ce1fdfdU, 0xae3d9393U, 0x6a4c2626U,
+    0x5a6c3636U, 0x417e3f3fU, 0x02f5f7f7U, 0x4f83ccccU,
+    0x5c683434U, 0xf451a5a5U, 0x34d1e5e5U, 0x08f9f1f1U,
+    0x93e27171U, 0x73abd8d8U, 0x53623131U, 0x3f2a1515U,
+    0x0c080404U, 0x5295c7c7U, 0x65462323U, 0x5e9dc3c3U,
+    0x28301818U, 0xa1379696U, 0x0f0a0505U, 0xb52f9a9aU,
+    0x090e0707U, 0x36241212U, 0x9b1b8080U, 0x3ddfe2e2U,
+    0x26cdebebU, 0x694e2727U, 0xcd7fb2b2U, 0x9fea7575U,
+    0x1b120909U, 0x9e1d8383U, 0x74582c2cU, 0x2e341a1aU,
+    0x2d361b1bU, 0xb2dc6e6eU, 0xeeb45a5aU, 0xfb5ba0a0U,
+    0xf6a45252U, 0x4d763b3bU, 0x61b7d6d6U, 0xce7db3b3U,
+    0x7b522929U, 0x3edde3e3U, 0x715e2f2fU, 0x97138484U,
+    0xf5a65353U, 0x68b9d1d1U, 0x00000000U, 0x2cc1ededU,
+    0x60402020U, 0x1fe3fcfcU, 0xc879b1b1U, 0xedb65b5bU,
+    0xbed46a6aU, 0x468dcbcbU, 0xd967bebeU, 0x4b723939U,
+    0xde944a4aU, 0xd4984c4cU, 0xe8b05858U, 0x4a85cfcfU,
+    0x6bbbd0d0U, 0x2ac5efefU, 0xe54faaaaU, 0x16edfbfbU,
+    0xc5864343U, 0xd79a4d4dU, 0x55663333U, 0x94118585U,
+    0xcf8a4545U, 0x10e9f9f9U, 0x06040202U, 0x81fe7f7fU,
+    0xf0a05050U, 0x44783c3cU, 0xba259f9fU, 0xe34ba8a8U,
+    0xf3a25151U, 0xfe5da3a3U, 0xc0804040U, 0x8a058f8fU,
+    0xad3f9292U, 0xbc219d9dU, 0x48703838U, 0x04f1f5f5U,
+    0xdf63bcbcU, 0xc177b6b6U, 0x75afdadaU, 0x63422121U,
+    0x30201010U, 0x1ae5ffffU, 0x0efdf3f3U, 0x6dbfd2d2U,
+    0x4c81cdcdU, 0x14180c0cU, 0x35261313U, 0x2fc3ececU,
+    0xe1be5f5fU, 0xa2359797U, 0xcc884444U, 0x392e1717U,
+    0x5793c4c4U, 0xf255a7a7U, 0x82fc7e7eU, 0x477a3d3dU,
+    0xacc86464U, 0xe7ba5d5dU, 0x2b321919U, 0x95e67373U,
+    0xa0c06060U, 0x98198181U, 0xd19e4f4fU, 0x7fa3dcdcU,
+    0x66442222U, 0x7e542a2aU, 0xab3b9090U, 0x830b8888U,
+    0xca8c4646U, 0x29c7eeeeU, 0xd36bb8b8U, 0x3c281414U,
+    0x79a7dedeU, 0xe2bc5e5eU, 0x1d160b0bU, 0x76addbdbU,
+    0x3bdbe0e0U, 0x56643232U, 0x4e743a3aU, 0x1e140a0aU,
+    0xdb924949U, 0x0a0c0606U, 0x6c482424U, 0xe4b85c5cU,
+    0x5d9fc2c2U, 0x6ebdd3d3U, 0xef43acacU, 0xa6c46262U,
+    0xa8399191U, 0xa4319595U, 0x37d3e4e4U, 0x8bf27979U,
+    0x32d5e7e7U, 0x438bc8c8U, 0x596e3737U, 0xb7da6d6dU,
+    0x8c018d8dU, 0x64b1d5d5U, 0xd29c4e4eU, 0xe049a9a9U,
+    0xb4d86c6cU, 0xfaac5656U, 0x07f3f4f4U, 0x25cfeaeaU,
+    0xafca6565U, 0x8ef47a7aU, 0xe947aeaeU, 0x18100808U,
+    0xd56fbabaU, 0x88f07878U, 0x6f4a2525U, 0x725c2e2eU,
+    0x24381c1cU, 0xf157a6a6U, 0xc773b4b4U, 0x5197c6c6U,
+    0x23cbe8e8U, 0x7ca1ddddU, 0x9ce87474U, 0x213e1f1fU,
+    0xdd964b4bU, 0xdc61bdbdU, 0x860d8b8bU, 0x850f8a8aU,
+    0x90e07070U, 0x427c3e3eU, 0xc471b5b5U, 0xaacc6666U,
+    0xd8904848U, 0x05060303U, 0x01f7f6f6U, 0x121c0e0eU,
+    0xa3c26161U, 0x5f6a3535U, 0xf9ae5757U, 0xd069b9b9U,
+    0x91178686U, 0x5899c1c1U, 0x273a1d1dU, 0xb9279e9eU,
+    0x38d9e1e1U, 0x13ebf8f8U, 0xb32b9898U, 0x33221111U,
+    0xbbd26969U, 0x70a9d9d9U, 0x89078e8eU, 0xa7339494U,
+    0xb62d9b9bU, 0x223c1e1eU, 0x92158787U, 0x20c9e9e9U,
+    0x4987ceceU, 0xffaa5555U, 0x78502828U, 0x7aa5dfdfU,
+    0x8f038c8cU, 0xf859a1a1U, 0x80098989U, 0x171a0d0dU,
+    0xda65bfbfU, 0x31d7e6e6U, 0xc6844242U, 0xb8d06868U,
+    0xc3824141U, 0xb0299999U, 0x775a2d2dU, 0x111e0f0fU,
+    0xcb7bb0b0U, 0xfca85454U, 0xd66dbbbbU, 0x3a2c1616U,
+};
+static const uint32_t Te2[256] = {
+    0x63a5c663U, 0x7c84f87cU, 0x7799ee77U, 0x7b8df67bU,
+    0xf20dfff2U, 0x6bbdd66bU, 0x6fb1de6fU, 0xc55491c5U,
+    0x30506030U, 0x01030201U, 0x67a9ce67U, 0x2b7d562bU,
+    0xfe19e7feU, 0xd762b5d7U, 0xabe64dabU, 0x769aec76U,
+    0xca458fcaU, 0x829d1f82U, 0xc94089c9U, 0x7d87fa7dU,
+    0xfa15effaU, 0x59ebb259U, 0x47c98e47U, 0xf00bfbf0U,
+    0xadec41adU, 0xd467b3d4U, 0xa2fd5fa2U, 0xafea45afU,
+    0x9cbf239cU, 0xa4f753a4U, 0x7296e472U, 0xc05b9bc0U,
+    0xb7c275b7U, 0xfd1ce1fdU, 0x93ae3d93U, 0x266a4c26U,
+    0x365a6c36U, 0x3f417e3fU, 0xf702f5f7U, 0xcc4f83ccU,
+    0x345c6834U, 0xa5f451a5U, 0xe534d1e5U, 0xf108f9f1U,
+    0x7193e271U, 0xd873abd8U, 0x31536231U, 0x153f2a15U,
+    0x040c0804U, 0xc75295c7U, 0x23654623U, 0xc35e9dc3U,
+    0x18283018U, 0x96a13796U, 0x050f0a05U, 0x9ab52f9aU,
+    0x07090e07U, 0x12362412U, 0x809b1b80U, 0xe23ddfe2U,
+    0xeb26cdebU, 0x27694e27U, 0xb2cd7fb2U, 0x759fea75U,
+    0x091b1209U, 0x839e1d83U, 0x2c74582cU, 0x1a2e341aU,
+    0x1b2d361bU, 0x6eb2dc6eU, 0x5aeeb45aU, 0xa0fb5ba0U,
+    0x52f6a452U, 0x3b4d763bU, 0xd661b7d6U, 0xb3ce7db3U,
+    0x297b5229U, 0xe33edde3U, 0x2f715e2fU, 0x84971384U,
+    0x53f5a653U, 0xd168b9d1U, 0x00000000U, 0xed2cc1edU,
+    0x20604020U, 0xfc1fe3fcU, 0xb1c879b1U, 0x5bedb65bU,
+    0x6abed46aU, 0xcb468dcbU, 0xbed967beU, 0x394b7239U,
+    0x4ade944aU, 0x4cd4984cU, 0x58e8b058U, 0xcf4a85cfU,
+    0xd06bbbd0U, 0xef2ac5efU, 0xaae54faaU, 0xfb16edfbU,
+    0x43c58643U, 0x4dd79a4dU, 0x33556633U, 0x85941185U,
+    0x45cf8a45U, 0xf910e9f9U, 0x02060402U, 0x7f81fe7fU,
+    0x50f0a050U, 0x3c44783cU, 0x9fba259fU, 0xa8e34ba8U,
+    0x51f3a251U, 0xa3fe5da3U, 0x40c08040U, 0x8f8a058fU,
+    0x92ad3f92U, 0x9dbc219dU, 0x38487038U, 0xf504f1f5U,
+    0xbcdf63bcU, 0xb6c177b6U, 0xda75afdaU, 0x21634221U,
+    0x10302010U, 0xff1ae5ffU, 0xf30efdf3U, 0xd26dbfd2U,
+    0xcd4c81cdU, 0x0c14180cU, 0x13352613U, 0xec2fc3ecU,
+    0x5fe1be5fU, 0x97a23597U, 0x44cc8844U, 0x17392e17U,
+    0xc45793c4U, 0xa7f255a7U, 0x7e82fc7eU, 0x3d477a3dU,
+    0x64acc864U, 0x5de7ba5dU, 0x192b3219U, 0x7395e673U,
+    0x60a0c060U, 0x81981981U, 0x4fd19e4fU, 0xdc7fa3dcU,
+    0x22664422U, 0x2a7e542aU, 0x90ab3b90U, 0x88830b88U,
+    0x46ca8c46U, 0xee29c7eeU, 0xb8d36bb8U, 0x143c2814U,
+    0xde79a7deU, 0x5ee2bc5eU, 0x0b1d160bU, 0xdb76addbU,
+    0xe03bdbe0U, 0x32566432U, 0x3a4e743aU, 0x0a1e140aU,
+    0x49db9249U, 0x060a0c06U, 0x246c4824U, 0x5ce4b85cU,
+    0xc25d9fc2U, 0xd36ebdd3U, 0xacef43acU, 0x62a6c462U,
+    0x91a83991U, 0x95a43195U, 0xe437d3e4U, 0x798bf279U,
+    0xe732d5e7U, 0xc8438bc8U, 0x37596e37U, 0x6db7da6dU,
+    0x8d8c018dU, 0xd564b1d5U, 0x4ed29c4eU, 0xa9e049a9U,
+    0x6cb4d86cU, 0x56faac56U, 0xf407f3f4U, 0xea25cfeaU,
+    0x65afca65U, 0x7a8ef47aU, 0xaee947aeU, 0x08181008U,
+    0xbad56fbaU, 0x7888f078U, 0x256f4a25U, 0x2e725c2eU,
+    0x1c24381cU, 0xa6f157a6U, 0xb4c773b4U, 0xc65197c6U,
+    0xe823cbe8U, 0xdd7ca1ddU, 0x749ce874U, 0x1f213e1fU,
+    0x4bdd964bU, 0xbddc61bdU, 0x8b860d8bU, 0x8a850f8aU,
+    0x7090e070U, 0x3e427c3eU, 0xb5c471b5U, 0x66aacc66U,
+    0x48d89048U, 0x03050603U, 0xf601f7f6U, 0x0e121c0eU,
+    0x61a3c261U, 0x355f6a35U, 0x57f9ae57U, 0xb9d069b9U,
+    0x86911786U, 0xc15899c1U, 0x1d273a1dU, 0x9eb9279eU,
+    0xe138d9e1U, 0xf813ebf8U, 0x98b32b98U, 0x11332211U,
+    0x69bbd269U, 0xd970a9d9U, 0x8e89078eU, 0x94a73394U,
+    0x9bb62d9bU, 0x1e223c1eU, 0x87921587U, 0xe920c9e9U,
+    0xce4987ceU, 0x55ffaa55U, 0x28785028U, 0xdf7aa5dfU,
+    0x8c8f038cU, 0xa1f859a1U, 0x89800989U, 0x0d171a0dU,
+    0xbfda65bfU, 0xe631d7e6U, 0x42c68442U, 0x68b8d068U,
+    0x41c38241U, 0x99b02999U, 0x2d775a2dU, 0x0f111e0fU,
+    0xb0cb7bb0U, 0x54fca854U, 0xbbd66dbbU, 0x163a2c16U,
+};
+static const uint32_t Te3[256] = {
+
+    0x6363a5c6U, 0x7c7c84f8U, 0x777799eeU, 0x7b7b8df6U,
+    0xf2f20dffU, 0x6b6bbdd6U, 0x6f6fb1deU, 0xc5c55491U,
+    0x30305060U, 0x01010302U, 0x6767a9ceU, 0x2b2b7d56U,
+    0xfefe19e7U, 0xd7d762b5U, 0xababe64dU, 0x76769aecU,
+    0xcaca458fU, 0x82829d1fU, 0xc9c94089U, 0x7d7d87faU,
+    0xfafa15efU, 0x5959ebb2U, 0x4747c98eU, 0xf0f00bfbU,
+    0xadadec41U, 0xd4d467b3U, 0xa2a2fd5fU, 0xafafea45U,
+    0x9c9cbf23U, 0xa4a4f753U, 0x727296e4U, 0xc0c05b9bU,
+    0xb7b7c275U, 0xfdfd1ce1U, 0x9393ae3dU, 0x26266a4cU,
+    0x36365a6cU, 0x3f3f417eU, 0xf7f702f5U, 0xcccc4f83U,
+    0x34345c68U, 0xa5a5f451U, 0xe5e534d1U, 0xf1f108f9U,
+    0x717193e2U, 0xd8d873abU, 0x31315362U, 0x15153f2aU,
+    0x04040c08U, 0xc7c75295U, 0x23236546U, 0xc3c35e9dU,
+    0x18182830U, 0x9696a137U, 0x05050f0aU, 0x9a9ab52fU,
+    0x0707090eU, 0x12123624U, 0x80809b1bU, 0xe2e23ddfU,
+    0xebeb26cdU, 0x2727694eU, 0xb2b2cd7fU, 0x75759feaU,
+    0x09091b12U, 0x83839e1dU, 0x2c2c7458U, 0x1a1a2e34U,
+    0x1b1b2d36U, 0x6e6eb2dcU, 0x5a5aeeb4U, 0xa0a0fb5bU,
+    0x5252f6a4U, 0x3b3b4d76U, 0xd6d661b7U, 0xb3b3ce7dU,
+    0x29297b52U, 0xe3e33eddU, 0x2f2f715eU, 0x84849713U,
+    0x5353f5a6U, 0xd1d168b9U, 0x00000000U, 0xeded2cc1U,
+    0x20206040U, 0xfcfc1fe3U, 0xb1b1c879U, 0x5b5bedb6U,
+    0x6a6abed4U, 0xcbcb468dU, 0xbebed967U, 0x39394b72U,
+    0x4a4ade94U, 0x4c4cd498U, 0x5858e8b0U, 0xcfcf4a85U,
+    0xd0d06bbbU, 0xefef2ac5U, 0xaaaae54fU, 0xfbfb16edU,
+    0x4343c586U, 0x4d4dd79aU, 0x33335566U, 0x85859411U,
+    0x4545cf8aU, 0xf9f910e9U, 0x02020604U, 0x7f7f81feU,
+    0x5050f0a0U, 0x3c3c4478U, 0x9f9fba25U, 0xa8a8e34bU,
+    0x5151f3a2U, 0xa3a3fe5dU, 0x4040c080U, 0x8f8f8a05U,
+    0x9292ad3fU, 0x9d9dbc21U, 0x38384870U, 0xf5f504f1U,
+    0xbcbcdf63U, 0xb6b6c177U, 0xdada75afU, 0x21216342U,
+    0x10103020U, 0xffff1ae5U, 0xf3f30efdU, 0xd2d26dbfU,
+    0xcdcd4c81U, 0x0c0c1418U, 0x13133526U, 0xecec2fc3U,
+    0x5f5fe1beU, 0x9797a235U, 0x4444cc88U, 0x1717392eU,
+    0xc4c45793U, 0xa7a7f255U, 0x7e7e82fcU, 0x3d3d477aU,
+    0x6464acc8U, 0x5d5de7baU, 0x19192b32U, 0x737395e6U,
+    0x6060a0c0U, 0x81819819U, 0x4f4fd19eU, 0xdcdc7fa3U,
+    0x22226644U, 0x2a2a7e54U, 0x9090ab3bU, 0x8888830bU,
+    0x4646ca8cU, 0xeeee29c7U, 0xb8b8d36bU, 0x14143c28U,
+    0xdede79a7U, 0x5e5ee2bcU, 0x0b0b1d16U, 0xdbdb76adU,
+    0xe0e03bdbU, 0x32325664U, 0x3a3a4e74U, 0x0a0a1e14U,
+    0x4949db92U, 0x06060a0cU, 0x24246c48U, 0x5c5ce4b8U,
+    0xc2c25d9fU, 0xd3d36ebdU, 0xacacef43U, 0x6262a6c4U,
+    0x9191a839U, 0x9595a431U, 0xe4e437d3U, 0x79798bf2U,
+    0xe7e732d5U, 0xc8c8438bU, 0x3737596eU, 0x6d6db7daU,
+    0x8d8d8c01U, 0xd5d564b1U, 0x4e4ed29cU, 0xa9a9e049U,
+    0x6c6cb4d8U, 0x5656faacU, 0xf4f407f3U, 0xeaea25cfU,
+    0x6565afcaU, 0x7a7a8ef4U, 0xaeaee947U, 0x08081810U,
+    0xbabad56fU, 0x787888f0U, 0x25256f4aU, 0x2e2e725cU,
+    0x1c1c2438U, 0xa6a6f157U, 0xb4b4c773U, 0xc6c65197U,
+    0xe8e823cbU, 0xdddd7ca1U, 0x74749ce8U, 0x1f1f213eU,
+    0x4b4bdd96U, 0xbdbddc61U, 0x8b8b860dU, 0x8a8a850fU,
+    0x707090e0U, 0x3e3e427cU, 0xb5b5c471U, 0x6666aaccU,
+    0x4848d890U, 0x03030506U, 0xf6f601f7U, 0x0e0e121cU,
+    0x6161a3c2U, 0x35355f6aU, 0x5757f9aeU, 0xb9b9d069U,
+    0x86869117U, 0xc1c15899U, 0x1d1d273aU, 0x9e9eb927U,
+    0xe1e138d9U, 0xf8f813ebU, 0x9898b32bU, 0x11113322U,
+    0x6969bbd2U, 0xd9d970a9U, 0x8e8e8907U, 0x9494a733U,
+    0x9b9bb62dU, 0x1e1e223cU, 0x87879215U, 0xe9e920c9U,
+    0xcece4987U, 0x5555ffaaU, 0x28287850U, 0xdfdf7aa5U,
+    0x8c8c8f03U, 0xa1a1f859U, 0x89898009U, 0x0d0d171aU,
+    0xbfbfda65U, 0xe6e631d7U, 0x4242c684U, 0x6868b8d0U,
+    0x4141c382U, 0x9999b029U, 0x2d2d775aU, 0x0f0f111eU,
+    0xb0b0cb7bU, 0x5454fca8U, 0xbbbbd66dU, 0x16163a2cU,
+};
+static const uint32_t Te4[256] = {
+    0x63636363U, 0x7c7c7c7cU, 0x77777777U, 0x7b7b7b7bU,
+    0xf2f2f2f2U, 0x6b6b6b6bU, 0x6f6f6f6fU, 0xc5c5c5c5U,
+    0x30303030U, 0x01010101U, 0x67676767U, 0x2b2b2b2bU,
+    0xfefefefeU, 0xd7d7d7d7U, 0xababababU, 0x76767676U,
+    0xcacacacaU, 0x82828282U, 0xc9c9c9c9U, 0x7d7d7d7dU,
+    0xfafafafaU, 0x59595959U, 0x47474747U, 0xf0f0f0f0U,
+    0xadadadadU, 0xd4d4d4d4U, 0xa2a2a2a2U, 0xafafafafU,
+    0x9c9c9c9cU, 0xa4a4a4a4U, 0x72727272U, 0xc0c0c0c0U,
+    0xb7b7b7b7U, 0xfdfdfdfdU, 0x93939393U, 0x26262626U,
+    0x36363636U, 0x3f3f3f3fU, 0xf7f7f7f7U, 0xccccccccU,
+    0x34343434U, 0xa5a5a5a5U, 0xe5e5e5e5U, 0xf1f1f1f1U,
+    0x71717171U, 0xd8d8d8d8U, 0x31313131U, 0x15151515U,
+    0x04040404U, 0xc7c7c7c7U, 0x23232323U, 0xc3c3c3c3U,
+    0x18181818U, 0x96969696U, 0x05050505U, 0x9a9a9a9aU,
+    0x07070707U, 0x12121212U, 0x80808080U, 0xe2e2e2e2U,
+    0xebebebebU, 0x27272727U, 0xb2b2b2b2U, 0x75757575U,
+    0x09090909U, 0x83838383U, 0x2c2c2c2cU, 0x1a1a1a1aU,
+    0x1b1b1b1bU, 0x6e6e6e6eU, 0x5a5a5a5aU, 0xa0a0a0a0U,
+    0x52525252U, 0x3b3b3b3bU, 0xd6d6d6d6U, 0xb3b3b3b3U,
+    0x29292929U, 0xe3e3e3e3U, 0x2f2f2f2fU, 0x84848484U,
+    0x53535353U, 0xd1d1d1d1U, 0x00000000U, 0xededededU,
+    0x20202020U, 0xfcfcfcfcU, 0xb1b1b1b1U, 0x5b5b5b5bU,
+    0x6a6a6a6aU, 0xcbcbcbcbU, 0xbebebebeU, 0x39393939U,
+    0x4a4a4a4aU, 0x4c4c4c4cU, 0x58585858U, 0xcfcfcfcfU,
+    0xd0d0d0d0U, 0xefefefefU, 0xaaaaaaaaU, 0xfbfbfbfbU,
+    0x43434343U, 0x4d4d4d4dU, 0x33333333U, 0x85858585U,
+    0x45454545U, 0xf9f9f9f9U, 0x02020202U, 0x7f7f7f7fU,
+    0x50505050U, 0x3c3c3c3cU, 0x9f9f9f9fU, 0xa8a8a8a8U,
+    0x51515151U, 0xa3a3a3a3U, 0x40404040U, 0x8f8f8f8fU,
+    0x92929292U, 0x9d9d9d9dU, 0x38383838U, 0xf5f5f5f5U,
+    0xbcbcbcbcU, 0xb6b6b6b6U, 0xdadadadaU, 0x21212121U,
+    0x10101010U, 0xffffffffU, 0xf3f3f3f3U, 0xd2d2d2d2U,
+    0xcdcdcdcdU, 0x0c0c0c0cU, 0x13131313U, 0xececececU,
+    0x5f5f5f5fU, 0x97979797U, 0x44444444U, 0x17171717U,
+    0xc4c4c4c4U, 0xa7a7a7a7U, 0x7e7e7e7eU, 0x3d3d3d3dU,
+    0x64646464U, 0x5d5d5d5dU, 0x19191919U, 0x73737373U,
+    0x60606060U, 0x81818181U, 0x4f4f4f4fU, 0xdcdcdcdcU,
+    0x22222222U, 0x2a2a2a2aU, 0x90909090U, 0x88888888U,
+    0x46464646U, 0xeeeeeeeeU, 0xb8b8b8b8U, 0x14141414U,
+    0xdedededeU, 0x5e5e5e5eU, 0x0b0b0b0bU, 0xdbdbdbdbU,
+    0xe0e0e0e0U, 0x32323232U, 0x3a3a3a3aU, 0x0a0a0a0aU,
+    0x49494949U, 0x06060606U, 0x24242424U, 0x5c5c5c5cU,
+    0xc2c2c2c2U, 0xd3d3d3d3U, 0xacacacacU, 0x62626262U,
+    0x91919191U, 0x95959595U, 0xe4e4e4e4U, 0x79797979U,
+    0xe7e7e7e7U, 0xc8c8c8c8U, 0x37373737U, 0x6d6d6d6dU,
+    0x8d8d8d8dU, 0xd5d5d5d5U, 0x4e4e4e4eU, 0xa9a9a9a9U,
+    0x6c6c6c6cU, 0x56565656U, 0xf4f4f4f4U, 0xeaeaeaeaU,
+    0x65656565U, 0x7a7a7a7aU, 0xaeaeaeaeU, 0x08080808U,
+    0xbabababaU, 0x78787878U, 0x25252525U, 0x2e2e2e2eU,
+    0x1c1c1c1cU, 0xa6a6a6a6U, 0xb4b4b4b4U, 0xc6c6c6c6U,
+    0xe8e8e8e8U, 0xddddddddU, 0x74747474U, 0x1f1f1f1fU,
+    0x4b4b4b4bU, 0xbdbdbdbdU, 0x8b8b8b8bU, 0x8a8a8a8aU,
+    0x70707070U, 0x3e3e3e3eU, 0xb5b5b5b5U, 0x66666666U,
+    0x48484848U, 0x03030303U, 0xf6f6f6f6U, 0x0e0e0e0eU,
+    0x61616161U, 0x35353535U, 0x57575757U, 0xb9b9b9b9U,
+    0x86868686U, 0xc1c1c1c1U, 0x1d1d1d1dU, 0x9e9e9e9eU,
+    0xe1e1e1e1U, 0xf8f8f8f8U, 0x98989898U, 0x11111111U,
+    0x69696969U, 0xd9d9d9d9U, 0x8e8e8e8eU, 0x94949494U,
+    0x9b9b9b9bU, 0x1e1e1e1eU, 0x87878787U, 0xe9e9e9e9U,
+    0xcecececeU, 0x55555555U, 0x28282828U, 0xdfdfdfdfU,
+    0x8c8c8c8cU, 0xa1a1a1a1U, 0x89898989U, 0x0d0d0d0dU,
+    0xbfbfbfbfU, 0xe6e6e6e6U, 0x42424242U, 0x68686868U,
+    0x41414141U, 0x99999999U, 0x2d2d2d2dU, 0x0f0f0f0fU,
+    0xb0b0b0b0U, 0x54545454U, 0xbbbbbbbbU, 0x16161616U,
+};
+static const uint32_t rcon[] = {
+    0x01000000, 0x02000000, 0x04000000, 0x08000000,
+    0x10000000, 0x20000000, 0x40000000, 0x80000000,
+    0x1B000000, 0x36000000, /* for 128-bit blocks, Rijndael never uses more than 10 rcon values */
+};
+
+#define GETU32(pt) (((uint32_t)(pt)[0] << 24) ^ ((uint32_t)(pt)[1] << 16) ^ ((uint32_t)(pt)[2] <<  8) ^ ((uint32_t)(pt)[3]))
+#define PUTU32(ct, st) { (ct)[0] = (uint8_t)((st) >> 24); (ct)[1] = (uint8_t)((st) >> 16); (ct)[2] = (uint8_t)((st) >>  8); (ct)[3] = (uint8_t)(st); }
+
+/**
+ * Expand the cipher key into the encryption key schedule.
+ *
+ * @return  the number of rounds for the given cipher key size.
+ */
+int rijndaelKeySetupEnc128(uint32_t rk[44], const uint8_t cipherKey[] ) {
+    int i = 0;
+    uint32_t temp;
+
+    rk[0] = GETU32(cipherKey     );
+    rk[1] = GETU32(cipherKey +  4);
+    rk[2] = GETU32(cipherKey +  8);
+    rk[3] = GETU32(cipherKey + 12);
+    for (;;) {
+        temp  = rk[3];
+        rk[4] = rk[0] ^
+            (Te4[(temp >> 16) & 0xff] & 0xff000000) ^
+            (Te4[(temp >>  8) & 0xff] & 0x00ff0000) ^
+            (Te4[(temp      ) & 0xff] & 0x0000ff00) ^
+            (Te4[(temp >> 24)       ] & 0x000000ff) ^
+            rcon[i];
+        rk[5] = rk[1] ^ rk[4];
+        rk[6] = rk[2] ^ rk[5];
+        rk[7] = rk[3] ^ rk[6];
+        if (++i == 10) {
+            return 10;
+        }
+        rk += 4;
+    }
+}
+
+void rijndaelEncrypt128(const uint32_t rk[44], const uint8_t pt[16], uint8_t ct[16]) {
+    uint32_t s0, s1, s2, s3, t0, t1, t2, t3;
+
+    /*
+     * map byte array block to cipher state
+     * and add initial round key:
+     */
+    s0 = GETU32(pt     ) ^ rk[0];
+    s1 = GETU32(pt +  4) ^ rk[1];
+    s2 = GETU32(pt +  8) ^ rk[2];
+    s3 = GETU32(pt + 12) ^ rk[3];
+    /* round 1: */
+    t0 = Te0[s0 >> 24] ^ Te1[(s1 >> 16) & 0xff] ^ Te2[(s2 >>  8) & 0xff] ^ Te3[s3 & 0xff] ^ rk[ 4];
+    t1 = Te0[s1 >> 24] ^ Te1[(s2 >> 16) & 0xff] ^ Te2[(s3 >>  8) & 0xff] ^ Te3[s0 & 0xff] ^ rk[ 5];
+    t2 = Te0[s2 >> 24] ^ Te1[(s3 >> 16) & 0xff] ^ Te2[(s0 >>  8) & 0xff] ^ Te3[s1 & 0xff] ^ rk[ 6];
+    t3 = Te0[s3 >> 24] ^ Te1[(s0 >> 16) & 0xff] ^ Te2[(s1 >>  8) & 0xff] ^ Te3[s2 & 0xff] ^ rk[ 7];
+    /* round 2: */
+    s0 = Te0[t0 >> 24] ^ Te1[(t1 >> 16) & 0xff] ^ Te2[(t2 >>  8) & 0xff] ^ Te3[t3 & 0xff] ^ rk[ 8];
+    s1 = Te0[t1 >> 24] ^ Te1[(t2 >> 16) & 0xff] ^ Te2[(t3 >>  8) & 0xff] ^ Te3[t0 & 0xff] ^ rk[ 9];
+    s2 = Te0[t2 >> 24] ^ Te1[(t3 >> 16) & 0xff] ^ Te2[(t0 >>  8) & 0xff] ^ Te3[t1 & 0xff] ^ rk[10];
+    s3 = Te0[t3 >> 24] ^ Te1[(t0 >> 16) & 0xff] ^ Te2[(t1 >>  8) & 0xff] ^ Te3[t2 & 0xff] ^ rk[11];
+    /* round 3: */
+    t0 = Te0[s0 >> 24] ^ Te1[(s1 >> 16) & 0xff] ^ Te2[(s2 >>  8) & 0xff] ^ Te3[s3 & 0xff] ^ rk[12];
+    t1 = Te0[s1 >> 24] ^ Te1[(s2 >> 16) & 0xff] ^ Te2[(s3 >>  8) & 0xff] ^ Te3[s0 & 0xff] ^ rk[13];
+    t2 = Te0[s2 >> 24] ^ Te1[(s3 >> 16) & 0xff] ^ Te2[(s0 >>  8) & 0xff] ^ Te3[s1 & 0xff] ^ rk[14];
+    t3 = Te0[s3 >> 24] ^ Te1[(s0 >> 16) & 0xff] ^ Te2[(s1 >>  8) & 0xff] ^ Te3[s2 & 0xff] ^ rk[15];
+    /* round 4: */
+    s0 = Te0[t0 >> 24] ^ Te1[(t1 >> 16) & 0xff] ^ Te2[(t2 >>  8) & 0xff] ^ Te3[t3 & 0xff] ^ rk[16];
+    s1 = Te0[t1 >> 24] ^ Te1[(t2 >> 16) & 0xff] ^ Te2[(t3 >>  8) & 0xff] ^ Te3[t0 & 0xff] ^ rk[17];
+    s2 = Te0[t2 >> 24] ^ Te1[(t3 >> 16) & 0xff] ^ Te2[(t0 >>  8) & 0xff] ^ Te3[t1 & 0xff] ^ rk[18];
+    s3 = Te0[t3 >> 24] ^ Te1[(t0 >> 16) & 0xff] ^ Te2[(t1 >>  8) & 0xff] ^ Te3[t2 & 0xff] ^ rk[19];
+    /* round 5: */
+    t0 = Te0[s0 >> 24] ^ Te1[(s1 >> 16) & 0xff] ^ Te2[(s2 >>  8) & 0xff] ^ Te3[s3 & 0xff] ^ rk[20];
+    t1 = Te0[s1 >> 24] ^ Te1[(s2 >> 16) & 0xff] ^ Te2[(s3 >>  8) & 0xff] ^ Te3[s0 & 0xff] ^ rk[21];
+    t2 = Te0[s2 >> 24] ^ Te1[(s3 >> 16) & 0xff] ^ Te2[(s0 >>  8) & 0xff] ^ Te3[s1 & 0xff] ^ rk[22];
+    t3 = Te0[s3 >> 24] ^ Te1[(s0 >> 16) & 0xff] ^ Te2[(s1 >>  8) & 0xff] ^ Te3[s2 & 0xff] ^ rk[23];
+    /* round 6: */
+    s0 = Te0[t0 >> 24] ^ Te1[(t1 >> 16) & 0xff] ^ Te2[(t2 >>  8) & 0xff] ^ Te3[t3 & 0xff] ^ rk[24];
+    s1 = Te0[t1 >> 24] ^ Te1[(t2 >> 16) & 0xff] ^ Te2[(t3 >>  8) & 0xff] ^ Te3[t0 & 0xff] ^ rk[25];
+    s2 = Te0[t2 >> 24] ^ Te1[(t3 >> 16) & 0xff] ^ Te2[(t0 >>  8) & 0xff] ^ Te3[t1 & 0xff] ^ rk[26];
+    s3 = Te0[t3 >> 24] ^ Te1[(t0 >> 16) & 0xff] ^ Te2[(t1 >>  8) & 0xff] ^ Te3[t2 & 0xff] ^ rk[27];
+    /* round 7: */
+    t0 = Te0[s0 >> 24] ^ Te1[(s1 >> 16) & 0xff] ^ Te2[(s2 >>  8) & 0xff] ^ Te3[s3 & 0xff] ^ rk[28];
+    t1 = Te0[s1 >> 24] ^ Te1[(s2 >> 16) & 0xff] ^ Te2[(s3 >>  8) & 0xff] ^ Te3[s0 & 0xff] ^ rk[29];
+    t2 = Te0[s2 >> 24] ^ Te1[(s3 >> 16) & 0xff] ^ Te2[(s0 >>  8) & 0xff] ^ Te3[s1 & 0xff] ^ rk[30];
+    t3 = Te0[s3 >> 24] ^ Te1[(s0 >> 16) & 0xff] ^ Te2[(s1 >>  8) & 0xff] ^ Te3[s2 & 0xff] ^ rk[31];
+    /* round 8: */
+    s0 = Te0[t0 >> 24] ^ Te1[(t1 >> 16) & 0xff] ^ Te2[(t2 >>  8) & 0xff] ^ Te3[t3 & 0xff] ^ rk[32];
+    s1 = Te0[t1 >> 24] ^ Te1[(t2 >> 16) & 0xff] ^ Te2[(t3 >>  8) & 0xff] ^ Te3[t0 & 0xff] ^ rk[33];
+    s2 = Te0[t2 >> 24] ^ Te1[(t3 >> 16) & 0xff] ^ Te2[(t0 >>  8) & 0xff] ^ Te3[t1 & 0xff] ^ rk[34];
+    s3 = Te0[t3 >> 24] ^ Te1[(t0 >> 16) & 0xff] ^ Te2[(t1 >>  8) & 0xff] ^ Te3[t2 & 0xff] ^ rk[35];
+    /* round 9: */
+    t0 = Te0[s0 >> 24] ^ Te1[(s1 >> 16) & 0xff] ^ Te2[(s2 >>  8) & 0xff] ^ Te3[s3 & 0xff] ^ rk[36];
+    t1 = Te0[s1 >> 24] ^ Te1[(s2 >> 16) & 0xff] ^ Te2[(s3 >>  8) & 0xff] ^ Te3[s0 & 0xff] ^ rk[37];
+    t2 = Te0[s2 >> 24] ^ Te1[(s3 >> 16) & 0xff] ^ Te2[(s0 >>  8) & 0xff] ^ Te3[s1 & 0xff] ^ rk[38];
+    t3 = Te0[s3 >> 24] ^ Te1[(s0 >> 16) & 0xff] ^ Te2[(s1 >>  8) & 0xff] ^ Te3[s2 & 0xff] ^ rk[39];
+
+    /*
+     * apply last round and
+     * map cipher state to byte array block:
+     */
+    s0 =
+        (Te4[(t0 >> 24)       ] & 0xff000000) ^
+        (Te4[(t1 >> 16) & 0xff] & 0x00ff0000) ^
+        (Te4[(t2 >>  8) & 0xff] & 0x0000ff00) ^
+        (Te4[(t3      ) & 0xff] & 0x000000ff) ^
+        rk[40];
+    PUTU32(ct     , s0);
+    s1 =
+        (Te4[(t1 >> 24)       ] & 0xff000000) ^
+        (Te4[(t2 >> 16) & 0xff] & 0x00ff0000) ^
+        (Te4[(t3 >>  8) & 0xff] & 0x0000ff00) ^
+        (Te4[(t0      ) & 0xff] & 0x000000ff) ^
+        rk[41];
+    PUTU32(ct +  4, s1);
+    s2 =
+        (Te4[(t2 >> 24)       ] & 0xff000000) ^
+        (Te4[(t3 >> 16) & 0xff] & 0x00ff0000) ^
+        (Te4[(t0 >>  8) & 0xff] & 0x0000ff00) ^
+        (Te4[(t1      ) & 0xff] & 0x000000ff) ^
+        rk[42];
+    PUTU32(ct +  8, s2);
+    s3 =
+        (Te4[(t3 >> 24)       ] & 0xff000000) ^
+        (Te4[(t0 >> 16) & 0xff] & 0x00ff0000) ^
+        (Te4[(t1 >>  8) & 0xff] & 0x0000ff00) ^
+        (Te4[(t2      ) & 0xff] & 0x000000ff) ^
+        rk[43];
+    PUTU32(ct + 12, s3);
+}
diff --git a/src/ot_rijndael.h b/src/ot_rijndael.h
new file mode 100644
index 0000000..1235215
--- /dev/null
+++ b/src/ot_rijndael.h
@@ -0,0 +1,20 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever.
+
+   The rijndael implementation was taken from
+
+     http://www.cs.ucdavis.edu/~rogaway/ocb/ocb-ref/rijndael-alg-fst.c
+
+   and modified to work with 128 bits (this is 10 rounds) only. */
+
+#ifndef OT_RIJNDAEL_H__
+#define OT_RIJNDAEL_H__
+
+#include <stdint.h>
+
+int rijndaelKeySetupEnc128(uint32_t rk[44], const uint8_t cipherKey[] );
+void rijndaelEncrypt128(const uint32_t rk[44], const uint8_t pt[16], uint8_t ct[16]);
+
+extern const char *g_version_rijndael_c;
+
+#endif
diff --git a/src/ot_scan.c b/src/ot_scan.c
new file mode 100644
index 0000000..3b8e87c
--- /dev/null
+++ b/src/ot_scan.c
@@ -0,0 +1,65 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Opentracker */
+#include "ot_scan.h"
+
+size_t scan_uint(const char *src, uint64_t *dest, uint64_t max) {
+  unsigned long long value;
+  char              *end;
+
+  if (*src < '0' || *src > '9')
+    return 0;
+
+  errno = 0;
+  value = strtoull(src, &end, 10);
+
+  if (errno == ERANGE || value > (unsigned long long)max)
+    return 0;
+
+  *dest = (uint64_t)value;
+  return (size_t)(end - src);
+}
+
+size_t scan_uint_bencode(const char *src, uint64_t *dest, uint64_t max) {
+  uint64_t value;
+  size_t   consumed = scan_uint(src, &value, max);
+
+  /* bencode writes no leading zeros, so anything longer than a single digit
+     must not begin with one. */
+  if (consumed > 1 && *src == '0')
+    return 0;
+
+  if (consumed)
+    *dest = value;
+
+  return consumed;
+}
+
+int scan_int(const char *src, size_t len, int64_t *dest) {
+  int64_t value  = 0;
+  int     negate = 0;
+
+  if (len && *src == '-')
+    --len, ++src, negate = 1;
+  if (!len)
+    return -1;
+
+  while (len--) {
+    if (*src < '0' || *src > '9')
+      return -1;
+    /* A twenty character field of nines does not fit, and silently wrapping
+       would magically heal a nonsense announce */
+    if (value > (INT64_MAX - (*src - '0')) / 10)
+      return -1;
+    value = 10 * value + (*src++ - '0');
+  }
+
+  *dest = negate ? -value : value;
+  return 0;
+}
diff --git a/src/ot_scan.h b/src/ot_scan.h
new file mode 100644
index 0000000..a79ec13
--- /dev/null
+++ b/src/ot_scan.h
@@ -0,0 +1,25 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_SCAN_H__
+#define OT_SCAN_H__
+
+#include <stddef.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/* Read an unsigned decimal number from src into dest and return how many
+   characters were consumed. Returns zero and leaves dest untouched when src
+   does not begin with a digit, or when the value would exceed max. */
+size_t scan_uint(const char *src, uint64_t *dest, uint64_t max);
+
+/* As scan_uint, but following the bencode integer grammar, which permits a
+   leading zero on zero alone. */
+size_t scan_uint_bencode(const char *src, uint64_t *dest, uint64_t max);
+
+/* Read a signed decimal number that has to take up exactly len characters,
+   which is how a value lifted out of a query string arrives. Returns 0, or
+   -1 leaving dest untouched. */
+int    scan_int(const char *src, size_t len, int64_t *dest);
+
+#endif
diff --git a/src/ot_socket.c b/src/ot_socket.c
new file mode 100644
index 0000000..79bb01a
--- /dev/null
+++ b/src/ot_socket.c
@@ -0,0 +1,310 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#define _GNU_SOURCE /* accept4 on glibc */
+#include <errno.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_ip.h"
+#include "ot_socket.h"
+
+static void sockaddr_from_ip(struct sockaddr_in6 *sa, const ot_ip6 ip, uint16_t port) {
+  memset(sa, 0, sizeof(*sa));
+  sa->sin6_family = AF_INET6;
+  sa->sin6_port   = htons(port);
+  memcpy(&sa->sin6_addr, ip, sizeof(ot_ip6));
+}
+
+/* Linux reports an IPv4 peer on a dual stack socket as a v4 mapped
+   sockaddr_in6, the BSDs and macOS hand back a plain sockaddr_in instead, so
+   both forms have to be read. */
+static void ip_from_sockaddr(ot_ip6 ip, uint16_t *port, const struct sockaddr_storage *ss) {
+  if (ss->ss_family == AF_INET) {
+    const struct sockaddr_in *sa = (const struct sockaddr_in *)ss;
+
+    memcpy(ip, ip_v4mapped_prefix, sizeof(ip_v4mapped_prefix));
+    memcpy(ip + sizeof(ip_v4mapped_prefix), &sa->sin_addr, 4);
+    *port = ntohs(sa->sin_port);
+  } else {
+    const struct sockaddr_in6 *sa = (const struct sockaddr_in6 *)ss;
+
+    memcpy(ip, &sa->sin6_addr, sizeof(ot_ip6));
+    *port = ntohs(sa->sin6_port);
+  }
+}
+
+int socket_set_blocking(int s, int blocking) {
+  int flags = fcntl(s, F_GETFL, 0);
+
+  if (flags == -1)
+    return -1;
+  return fcntl(s, F_SETFL, blocking ? (flags & ~O_NONBLOCK) : (flags | O_NONBLOCK));
+}
+
+static int set_nonblocking(int s) { return socket_set_blocking(s, 0); }
+
+/* Close without letting the failure we are about to report be overwritten */
+static int close_and_fail(int s) {
+  int saved = errno;
+  close(s);
+  errno = saved;
+  return -1;
+}
+
+static int socket_v6(int type) {
+  int s = socket(PF_INET6, type, 0);
+  int zero = 0;
+
+  if (s == -1)
+    return -1;
+
+  /* A tracker that answered only one family would be half a tracker */
+  if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &zero, sizeof(zero)) == -1)
+    return close_and_fail(s);
+
+  if (set_nonblocking(s) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+/* SO_REUSEPORT means three different things. Linux spreads datagrams over
+   the group. FreeBSD permits the bind and spreads nothing, which is what
+   SO_REUSEPORT_LB was added for. Darwin hands every datagram to whichever
+   socket bound last, so a group there starves all but one reader. */
+#if defined(SO_REUSEPORT_LB)
+#define OT_BALANCE_OPTION SO_REUSEPORT_LB
+#elif defined(SO_REUSEPORT) && !defined(__APPLE__)
+#define OT_BALANCE_OPTION SO_REUSEPORT
+#endif
+
+int socket_can_balance(void) {
+#ifdef OT_BALANCE_OPTION
+  return 1;
+#else
+  return 0;
+#endif
+}
+
+/* The only place in the tree that needs to know what a kernel calls this */
+static void socket_set_sharing(int s, socket_sharing sharing) {
+  int one = 1;
+
+  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+#ifdef OT_BALANCE_OPTION
+  if (sharing == SOCKET_BALANCED) {
+    setsockopt(s, SOL_SOCKET, OT_BALANCE_OPTION, &one, sizeof(one));
+    return;
+  }
+#endif
+#ifdef SO_REUSEPORT
+  if (sharing != SOCKET_EXCLUSIVE)
+    setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+#endif
+}
+
+static int socket_bind_v6(int s, const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
+  struct sockaddr_in6 sa;
+
+  socket_set_sharing(s, sharing);
+
+  sockaddr_from_ip(&sa, ip, port);
+  return bind(s, (struct sockaddr *)&sa, sizeof(sa));
+}
+
+/* Defer the listening socket reporting it to be ready to accept until enough
+   sensible data is available for an accept+read pair. Where available. */
+int socket_defer_accept(int s) {
+#if defined(TCP_DEFER_ACCEPT)
+  int patience = OT_CLIENT_TIMEOUT;
+
+  return setsockopt(s, IPPROTO_TCP, TCP_DEFER_ACCEPT, &patience, sizeof(patience));
+#elif defined(SO_ACCEPTFILTER)
+  struct accept_filter_arg filter;
+  const char               name[sizeof(filter.af_name)] = "dataready";
+
+  memset(&filter, 0, sizeof(filter));
+  memcpy(filter.af_name, name, sizeof(name));
+  return setsockopt(s, SOL_SOCKET, SO_ACCEPTFILTER, &filter, sizeof(filter));
+#else
+  (void)s;
+  return -1;
+#endif
+}
+
+int socket_tcp_listen(const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
+  int s = socket_v6(SOCK_STREAM);
+
+  if (s == -1)
+    return -1;
+  if (socket_bind_v6(s, ip, port, sharing) == -1 || listen(s, SOMAXCONN) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+int socket_udp_bind(const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
+  int s = socket_v6(SOCK_DGRAM);
+
+  if (s == -1)
+    return -1;
+  if (socket_bind_v6(s, ip, port, sharing) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+int socket_tcp_connect(const ot_ip6 srcip, uint16_t srcport, const ot_ip6 dstip, uint16_t dstport) {
+  struct sockaddr_in6 sa;
+  int                 s = socket_v6(SOCK_STREAM);
+
+  if (s == -1)
+    return -1;
+  if (socket_bind_v6(s, srcip, srcport, SOCKET_EXCLUSIVE) == -1)
+    return close_and_fail(s);
+
+  sockaddr_from_ip(&sa, dstip, dstport);
+  if (connect(s, (struct sockaddr *)&sa, sizeof(sa)) == -1 && errno != EINPROGRESS && errno != EWOULDBLOCK)
+    return close_and_fail(s);
+
+  return s;
+}
+
+int socket_is_connected(int s) {
+  int       error = 0;
+  socklen_t len   = sizeof(error);
+
+  if (getsockopt(s, SOL_SOCKET, SO_ERROR, &error, &len) == -1)
+    return 0;
+  if (error) {
+    errno = error;
+    return 0;
+  }
+  return 1;
+}
+
+/* Linux hands over a blocking socket whatever the listening socket was, the
+   BSDs and macOS inherit the listener's flags, so the accepted socket has to
+   be told either way. accept4 carries the flag itself, which saves the two
+   fcntl calls it otherwise takes. Darwin has neither accept4 nor the flag. */
+int socket_accept(int s, ot_ip6 ip, uint16_t *port) {
+  struct sockaddr_storage ss;
+  socklen_t               len = sizeof(ss);
+  int                     fd;
+
+  memset(&ss, 0, sizeof(ss));
+#ifdef SOCK_NONBLOCK
+  if ((fd = accept4(s, (struct sockaddr *)&ss, &len, SOCK_NONBLOCK)) == -1)
+    return -1;
+#else
+  if ((fd = accept(s, (struct sockaddr *)&ss, &len)) == -1)
+    return -1;
+  if (set_nonblocking(fd) == -1)
+    return close_and_fail(fd);
+#endif
+
+  ip_from_sockaddr(ip, port, &ss);
+  return fd;
+}
+
+ssize_t socket_recv(int s, void *buf, size_t len, ot_ip6 ip, uint16_t *port) {
+  struct sockaddr_storage ss;
+  socklen_t               sslen = sizeof(ss);
+  ssize_t                 received;
+
+  memset(&ss, 0, sizeof(ss));
+  received = recvfrom(s, buf, len, 0, (struct sockaddr *)&ss, &sslen);
+  if (received == -1)
+    return -1;
+
+  ip_from_sockaddr(ip, port, &ss);
+  return received;
+}
+
+ssize_t socket_send(int s, const void *buf, size_t len, const ot_ip6 ip, uint16_t port) {
+  struct sockaddr_in6 sa;
+
+  sockaddr_from_ip(&sa, ip, port);
+  return sendto(s, buf, len, 0, (struct sockaddr *)&sa, sizeof(sa));
+}
+
+#ifdef WANT_SYNC_LIVE
+static void sockaddr4_from_ip(struct sockaddr_in *sa, const ot_ip6 ip, uint16_t port) {
+  memset(sa, 0, sizeof(*sa));
+  sa->sin_family = AF_INET;
+  sa->sin_port   = htons(port);
+  memcpy(&sa->sin_addr, ip + sizeof(ip_v4mapped_prefix), 4);
+}
+
+/* A multicast group is meant to have several listeners, so these are always
+   shared */
+static int socket_v4_bind(const ot_ip6 ip, uint16_t port) {
+  struct sockaddr_in sa;
+  int                s;
+
+  if ((s = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
+    return -1;
+
+  socket_set_sharing(s, SOCKET_SHARED);
+
+  sockaddr4_from_ip(&sa, ip, port);
+  if (bind(s, (struct sockaddr *)&sa, sizeof(sa)) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+int socket_mcast_join(const ot_ip6 group, const ot_ip6 interface, uint16_t port) {
+  struct ip_mreq mreq;
+  ot_ip6         any;
+  int            s;
+
+  /* The group is what is listened to, so the socket takes the wildcard and
+     the join names the interface to receive it on */
+  memcpy(any, ip_v4mapped_prefix, sizeof(ip_v4mapped_prefix));
+  memset(any + sizeof(ip_v4mapped_prefix), 0, 4);
+
+  if ((s = socket_v4_bind(any, port)) == -1)
+    return -1;
+
+  memset(&mreq, 0, sizeof(mreq));
+  memcpy(&mreq.imr_multiaddr, group + sizeof(ip_v4mapped_prefix), 4);
+  memcpy(&mreq.imr_interface, interface + sizeof(ip_v4mapped_prefix), 4);
+  if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+int socket_mcast_bind(const ot_ip6 interface, uint16_t port, int loopback) {
+  /* The BSDs and macOS want a byte for the IPv4 multicast options, Linux
+     accepts either that or an int. */
+  unsigned char ttl = 1, loop = (unsigned char)(loopback != 0);
+  int           s   = socket_v4_bind(interface, port);
+
+  if (s == -1)
+    return -1;
+  if (set_nonblocking(s) == -1)
+    return close_and_fail(s);
+
+  if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) == -1 ||
+      setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) == -1)
+    return close_and_fail(s);
+
+  return s;
+}
+
+ssize_t socket_mcast_send(int s, const void *buf, size_t len, const ot_ip6 group, uint16_t port) {
+  struct sockaddr_in sa;
+
+  sockaddr4_from_ip(&sa, group, port);
+  return sendto(s, buf, len, 0, (struct sockaddr *)&sa, sizeof(sa));
+}
+#endif
diff --git a/src/ot_socket.h b/src/ot_socket.h
new file mode 100644
index 0000000..5c1d840
--- /dev/null
+++ b/src/ot_socket.h
@@ -0,0 +1,56 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_SOCKET_H__
+#define OT_SOCKET_H__
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include "trackerlogic.h"
+
+/* Every socket opentracker opens is an AF_INET6 socket with IPV6_V6ONLY
+   cleared, so one descriptor serves both families and an IPv4 peer arrives
+   as the v4 mapped address */
+
+/* How an address may be shared with other sockets. Which socket option says
+   so differs between kernels, which is socket_set_sharing's business.
+
+   SHARED lets another socket bind the same address. BALANCED asks the kernel
+   to spread arriving datagrams over the sockets that did, which is a
+   different thing and not everywhere available: ask socket_can_balance
+   before binding a group that depends on it. */
+typedef enum { SOCKET_EXCLUSIVE, SOCKET_SHARED, SOCKET_BALANCED } socket_sharing;
+
+/* Whether this kernel spreads datagrams over a group of sockets bound to one
+   address. Where it does not, binding a group is worse than one socket with
+   several readers, so the caller wants to know first. */
+int     socket_can_balance(void);
+
+/* Create, bind and, for TCP, listen. The returned socket is non blocking
+   Returns -1 on failure with errno set */
+int     socket_tcp_listen(const ot_ip6 ip, uint16_t port, socket_sharing sharing);
+int     socket_udp_bind(const ot_ip6 ip, uint16_t port, socket_sharing sharing);
+
+int     socket_tcp_connect(const ot_ip6 srcip, uint16_t srcport, const ot_ip6 dstip, uint16_t dstport);
+int     socket_is_connected(int s);
+int     socket_accept(int s, ot_ip6 ip, uint16_t *port);
+int     socket_set_blocking(int s, int blocking);
+int     socket_defer_accept(int s);
+
+ssize_t socket_recv(int s, void *buf, size_t len, ot_ip6 ip, uint16_t *port);
+ssize_t socket_send(int s, const void *buf, size_t len, const ot_ip6 ip, uint16_t port);
+
+#ifdef WANT_SYNC_LIVE
+/*
+   socket_mcast_join takes the wildcard address and names the interface in the
+   join, and hands back a blocking socket, since the thread that reads it does
+   nothing else. socket_mcast_bind hands back a non blocking one, because the
+   thread that sends from it is also serving clients. Incoming datagrams are
+   read with socket_recv */
+int     socket_mcast_join(const ot_ip6 group, const ot_ip6 interface, uint16_t port);
+int     socket_mcast_bind(const ot_ip6 interface, uint16_t port, int loopback);
+ssize_t socket_mcast_send(int s, const void *buf, size_t len, const ot_ip6 group, uint16_t port);
+#endif
+
+#endif
diff --git a/src/ot_stats.c b/src/ot_stats.c
new file mode 100644
index 0000000..2d6335b
--- /dev/null
+++ b/src/ot_stats.c
@@ -0,0 +1,866 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+ It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#ifdef WANT_SYSLOGS
+#include <syslog.h>
+#endif
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_event.h"
+#include "ot_hex.h"
+#include "ot_iovec.h"
+#include "ot_ip.h"
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+#include "ot_fmt.h"
+#include "ot_stats.h"
+#include "trackerlogic.h"
+
+#ifndef NO_FULLSCRAPE_LOGGING
+#define LOG_TO_STDERR(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define LOG_TO_STDERR(...)
+#endif
+
+/* Forward declaration */
+static void stats_make(size_t *iovec_entries, struct iovec **iovector, ot_tasktype mode);
+#define OT_STATS_TMPSIZE 8192
+
+/* Each serving thread keeps its own statistics tally. The list is linked
+   through intrusive next pointers within the workstruct.
+
+   Registration happens once per thread and the adding up once per statistics
+   request, so this lock is never on anybody's hot path. */
+static struct ot_workstruct *g_counter_contexts;
+static ot_counter            g_retired[OT_COUNTER_COUNT];
+static pthread_mutex_t       g_counter_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void stats_counters_register(struct ot_workstruct *ws) {
+  pthread_mutex_lock(&g_counter_mutex);
+  ws->counters_next = g_counter_contexts;
+  g_counter_contexts = ws;
+  pthread_mutex_unlock(&g_counter_mutex);
+}
+
+void stats_counters_retire(struct ot_workstruct *ws) {
+  struct ot_workstruct **link;
+  size_t                 i;
+
+  pthread_mutex_lock(&g_counter_mutex);
+  for (link = &g_counter_contexts; *link; link = &(*link)->counters_next)
+    if (*link == ws) {
+      *link = ws->counters_next;
+      break;
+    }
+
+  /* When retiring a worker thread, collect the counter tally in the global */
+  for (i = 0; i < OT_COUNTER_COUNT; ++i)
+    atomic_fetch_add_explicit(g_retired + i, atomic_load_explicit(ws->counters + i, memory_order_relaxed), memory_order_relaxed);
+  pthread_mutex_unlock(&g_counter_mutex);
+}
+
+/* What every thread has counted so far, added together */
+static void counters_total(unsigned long long *total) {
+  struct ot_workstruct *ws;
+  size_t                i;
+
+  pthread_mutex_lock(&g_counter_mutex);
+  for (i = 0; i < OT_COUNTER_COUNT; ++i)
+    total[i] = atomic_load_explicit(g_retired + i, memory_order_relaxed);
+  for (ws = g_counter_contexts; ws; ws = ws->counters_next)
+    for (i = 0; i < OT_COUNTER_COUNT; ++i)
+      total[i] += atomic_load_explicit(ws->counters + i, memory_order_relaxed);
+  pthread_mutex_unlock(&g_counter_mutex);
+}
+
+#define COUNT(index, by) atomic_fetch_add_explicit(ws->counters + (index), (unsigned long long)(by), memory_order_relaxed)
+
+static const char        *ot_failed_request_names[] = {
+    "302 Redirect", "400 Parse Error", "400 Invalid Parameter", "400 Invalid Parameter (compact=0)", "400 Not Modest",
+    "402 Payment Required", "403 Access Denied", "404 Not found", "500 Internal Server Error"};
+
+static time_t             ot_start_time;
+
+#define STATS_NETWORK_NODE_BITWIDTH 4
+#define STATS_NETWORK_NODE_COUNT    (1 << STATS_NETWORK_NODE_BITWIDTH)
+
+#define __BYTE(P, D)                (((uint8_t *)P)[D / 8])
+#define __MSK                       (STATS_NETWORK_NODE_COUNT - 1)
+#define __SHFT(D)                   ((D ^ STATS_NETWORK_NODE_BITWIDTH) & STATS_NETWORK_NODE_BITWIDTH)
+
+#define __LDR(P, D)                 ((__BYTE((P), (D)) >> __SHFT((D))) & __MSK)
+#define __STR(P, D, V)              __BYTE((P), (D)) = (__BYTE((P), (D)) & ~(__MSK << __SHFT((D)))) | ((V) << __SHFT((D)))
+
+#if 0
+// XXX
+#define STATS_NETWORK_NODE_MAXDEPTH (68 - STATS_NETWORK_NODE_BITWIDTH)
+#define STATS_NETWORK_NODE_LIMIT    (48 - STATS_NETWORK_NODE_BITWIDTH)
+#endif
+#define STATS_NETWORK_NODE_MAXDEPTH (28 - STATS_NETWORK_NODE_BITWIDTH)
+#define STATS_NETWORK_NODE_LIMIT    (24 - STATS_NETWORK_NODE_BITWIDTH)
+
+typedef union stats_network_node stats_network_node;
+union stats_network_node {
+  size_t              counters[STATS_NETWORK_NODE_COUNT];
+  stats_network_node *children[STATS_NETWORK_NODE_COUNT];
+};
+
+static int stat_increase_network_count(stats_network_node **pnode, int depth, uintptr_t ip) {
+  int                 foo = __LDR(ip, depth);
+  stats_network_node *node;
+
+  if (!*pnode) {
+    *pnode = malloc(sizeof(stats_network_node));
+    if (!*pnode)
+      return -1;
+    memset(*pnode, 0, sizeof(stats_network_node));
+  }
+  node = *pnode;
+
+  if (depth < STATS_NETWORK_NODE_MAXDEPTH)
+    return stat_increase_network_count(node->children + foo, depth + STATS_NETWORK_NODE_BITWIDTH, ip);
+
+  node->counters[foo]++;
+  return 0;
+}
+
+static int stats_shift_down_network_count(stats_network_node **node, int depth, int shift) {
+  size_t i, rest = 0;
+
+  if (!*node)
+    return 0;
+
+  for (i = 0; i < STATS_NETWORK_NODE_COUNT; ++i)
+    if (depth < STATS_NETWORK_NODE_MAXDEPTH)
+      rest += stats_shift_down_network_count((*node)->children + i, depth + STATS_NETWORK_NODE_BITWIDTH, shift);
+    else
+      rest += (*node)->counters[i] >>= shift;
+
+  if (!rest) {
+    free(*node);
+    *node = NULL;
+  }
+
+  return rest;
+}
+
+static size_t stats_get_highscore_networks(stats_network_node *node, int depth, ot_ip6 node_value, size_t *scores, ot_ip6 *networks, int network_count,
+                                           int limit) {
+  size_t i, score = 0;
+
+  if (!node)
+    return 0;
+
+  if (depth < limit) {
+    for (i = 0; i < STATS_NETWORK_NODE_COUNT; ++i)
+      if (node->children[i]) {
+        __STR(node_value, depth, i);
+        score += stats_get_highscore_networks(node->children[i], depth + STATS_NETWORK_NODE_BITWIDTH, node_value, scores, networks, network_count, limit);
+      }
+    return score;
+  }
+
+  if (depth > limit && depth < STATS_NETWORK_NODE_MAXDEPTH) {
+    for (i = 0; i < STATS_NETWORK_NODE_COUNT; ++i)
+      if (node->children[i])
+        score += stats_get_highscore_networks(node->children[i], depth + STATS_NETWORK_NODE_BITWIDTH, node_value, scores, networks, network_count, limit);
+    return score;
+  }
+
+  if (depth > limit && depth == STATS_NETWORK_NODE_MAXDEPTH) {
+    for (i = 0; i < STATS_NETWORK_NODE_COUNT; ++i)
+      score += node->counters[i];
+    return score;
+  }
+
+  /* if( depth == limit ) */
+  for (i = 0; i < STATS_NETWORK_NODE_COUNT; ++i) {
+    int    j = 1;
+    size_t node_score;
+
+    if (depth == STATS_NETWORK_NODE_MAXDEPTH)
+      node_score = node->counters[i];
+    else
+      node_score = stats_get_highscore_networks(node->children[i], depth + STATS_NETWORK_NODE_BITWIDTH, node_value, scores, networks, network_count, limit);
+
+    score += node_score;
+
+    if (node_score <= scores[0])
+      continue;
+
+    __STR(node_value, depth, i);
+    while (j < network_count && node_score > scores[j])
+      ++j;
+    --j;
+
+    memmove(scores, scores + 1, j * sizeof(*scores));
+    memmove(networks, networks + 1, j * sizeof(*networks));
+    scores[j] = node_score;
+    memcpy(networks + j, node_value, sizeof(*networks));
+  }
+
+  return score;
+}
+
+static void stats_return_busy_networks(char **reply, const char *reply_end, stats_network_node *tree, size_t amount, int limit) {
+  ot_ip6 networks[amount];
+  ot_ip6 node_value;
+  size_t scores[amount];
+  size_t i;
+
+  memset(scores, 0, sizeof(scores));
+  memset(networks, 0, sizeof(networks));
+  memset(node_value, 0, sizeof(node_value));
+
+  stats_get_highscore_networks(tree, 0, node_value, scores, networks, amount, limit);
+
+  fmt_append(reply, reply_end, "Networks, limit /%d:\n", limit + STATS_NETWORK_NODE_BITWIDTH);
+  for (i = amount; i > 0; --i) {
+    if (scores[i - 1]) {
+      char ip_readable[64];
+
+      ip_readable[ip_format(ip_readable, networks[i - 1])] = 0;
+      fmt_append(reply, reply_end, "%08zd: %s\n", scores[i - 1], ip_readable);
+    }
+  }
+  fmt_append(reply, reply_end, "\n");
+}
+
+static void stats_slash24s_txt(char **reply, const char *reply_end, size_t amount) {
+  stats_network_node *slash24s_network_counters_root = NULL;
+  size_t              i, bucket, peer_size = OT_PEER_SIZE4;
+
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    ot_vector *torrents_list = mutex_bucket_lock(bucket);
+    for (i = 0; i < torrents_list->size; ++i) {
+      ot_peerlist *peer_list   = (((ot_torrent *)(torrents_list->data))[i]).peer_list4;
+      ot_vector   *bucket_list = &peer_list->peers;
+      int          num_buckets = 1;
+
+      if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+        num_buckets = bucket_list->size;
+        bucket_list = (ot_vector *)bucket_list->data;
+      }
+
+      while (num_buckets--) {
+        ot_peer *peers    = (ot_peer *)bucket_list->data;
+        size_t   numpeers = bucket_list->size;
+        while (numpeers--) {
+          if (stat_increase_network_count(&slash24s_network_counters_root, 0, (uintptr_t)(peers)))
+            goto bailout_unlock;
+          peers += peer_size;
+        }
+        ++bucket_list;
+      }
+    }
+    mutex_bucket_unlock(bucket, 0);
+    if (!g_opentracker_running)
+      goto done;
+  }
+
+  /* The tree is built. Now analyze */
+  stats_return_busy_networks(reply, reply_end, slash24s_network_counters_root, amount, STATS_NETWORK_NODE_MAXDEPTH);
+  stats_return_busy_networks(reply, reply_end, slash24s_network_counters_root, amount, STATS_NETWORK_NODE_LIMIT);
+  goto done;
+
+bailout_unlock:
+  mutex_bucket_unlock(bucket, 0);
+done:
+  stats_shift_down_network_count(&slash24s_network_counters_root, 0, sizeof(int) * 8 - 1);
+}
+
+#ifdef WANT_SPOT_WOODPECKER
+static stats_network_node *stats_woodpeckers_tree;
+static pthread_mutex_t     g_woodpeckers_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void              stats_return_woodpeckers(char **reply, const char *reply_end, int amount) {
+  pthread_mutex_lock(&g_woodpeckers_mutex);
+  stats_return_busy_networks(reply, reply_end, stats_woodpeckers_tree, amount, STATS_NETWORK_NODE_MAXDEPTH);
+  pthread_mutex_unlock(&g_woodpeckers_mutex);
+}
+#endif
+
+typedef struct {
+  unsigned long long torrent_count;
+  unsigned long long peer_count;
+  unsigned long long seed_count;
+} torrent_stats;
+
+static int torrent_statter(ot_torrent *torrent, uintptr_t data) {
+  torrent_stats *stats = (torrent_stats *)data;
+  stats->torrent_count++;
+  stats->peer_count += torrent->peer_list6->peer_count + torrent->peer_list4->peer_count;
+  stats->seed_count += torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+  return 0;
+}
+
+/* Converter function from memory to human readable hex strings */
+typedef struct {
+  size_t  val;
+  ot_hash hash;
+} ot_record;
+
+static inline void stats_insert_into_highscore(size_t val, ot_record* list, size_t amount, ot_hash* hash) {
+  size_t i;
+  for (i = 0; (i < amount) && (list[i].val > val); ++i)
+     {}
+  /* if we score better than a record in the list, we need to make room in the high
+     score array by moving lower scoring entries up */
+  if (i < amount) {
+    memmove(list + i + 1, list + i, (amount - i - 1) * sizeof(ot_record));
+
+    memcpy(&list[i].hash, hash, sizeof(ot_hash));
+    list[i].val = val;
+  }
+}
+
+
+/* Fetches stats from tracker */
+void stats_top_txt(char **reply, const char *reply_end, size_t amount) {
+  size_t    j, idx, bucket;
+  ot_record top100s[100], top100c[100], top100l[100];
+  char      hex_out[42];
+
+  if (amount > 100)
+    amount = 100;
+
+  memset(top100s, 0, sizeof(top100s));
+  memset(top100c, 0, sizeof(top100c));
+  memset(top100l, 0, sizeof(top100l));
+
+  /* Iterate over complete torrent list */
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    ot_vector *torrents_list = mutex_bucket_lock(bucket);
+    for (j = 0; j < torrents_list->size; ++j) {
+      ot_torrent *torrent     = (ot_torrent *)(torrents_list->data) + j;
+      size_t      peer_count  = torrent->peer_list6->peer_count + torrent->peer_list4->peer_count;
+      size_t      seed_count  = torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+      size_t      leech_count = peer_count - seed_count;
+
+      stats_insert_into_highscore(peer_count,  top100c, amount, &torrent->hash);
+      stats_insert_into_highscore(seed_count,  top100s, amount, &torrent->hash);
+      stats_insert_into_highscore(leech_count, top100l, amount, &torrent->hash);
+    }
+    mutex_bucket_unlock(bucket, 0);
+    if (!g_opentracker_running)
+      return;
+  }
+
+  fmt_append(reply, reply_end, "Top %zd torrents by peers:\n", amount);
+  for (idx = 0; idx < amount; ++idx)
+    if (top100c[idx].val)
+      fmt_append(reply, reply_end, "\t%zd\t%s\n", top100c[idx].val, hex_from_hash(hex_out, top100c[idx].hash));
+  fmt_append(reply, reply_end, "Top %zd torrents by seeds:\n", amount);
+  for (idx = 0; idx < amount; ++idx)
+    if (top100s[idx].val)
+      fmt_append(reply, reply_end, "\t%zd\t%s\n", top100s[idx].val, hex_from_hash(hex_out, top100s[idx].hash));
+  fmt_append(reply, reply_end, "Top %zd torrents by leechers:\n", amount);
+  for (idx = 0; idx < amount; ++idx)
+    if (top100l[idx].val)
+      fmt_append(reply, reply_end, "\t%zd\t%s\n", top100l[idx].val, hex_from_hash(hex_out, top100l[idx].hash));
+}
+
+static unsigned long events_per_time(unsigned long long events, time_t t) { return events / ((unsigned int)t ? (unsigned int)t : 1); }
+
+static void        stats_connections_mrtg(char **reply, const char *reply_end) {
+  ot_time t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker connections, %lu conns/s :: %lu success/s.",
+                    total[OT_COUNTER_TCP_CONNECTIONS] + total[OT_COUNTER_UDP_CONNECTIONS],
+                    total[OT_COUNTER_TCP_ANNOUNCES] + total[OT_COUNTER_UDP_ANNOUNCES] + total[OT_COUNTER_UDP_CONNECTS], (int)t, (int)(t / 3600),
+                    events_per_time(total[OT_COUNTER_TCP_CONNECTIONS] + total[OT_COUNTER_UDP_CONNECTIONS], t),
+                    events_per_time(total[OT_COUNTER_TCP_ANNOUNCES] + total[OT_COUNTER_UDP_ANNOUNCES] + total[OT_COUNTER_UDP_CONNECTS], t));
+}
+
+static void stats_udpconnections_mrtg(char **reply, const char *reply_end) {
+  ot_time t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker udp4 stats, %lu conns/s :: %lu success/s.", total[OT_COUNTER_UDP_CONNECTIONS],
+                    total[OT_COUNTER_UDP_ANNOUNCES] + total[OT_COUNTER_UDP_CONNECTS], (int)t, (int)(t / 3600),
+                    events_per_time(total[OT_COUNTER_UDP_CONNECTIONS], t),
+                    events_per_time(total[OT_COUNTER_UDP_ANNOUNCES] + total[OT_COUNTER_UDP_CONNECTS], t));
+}
+
+static void stats_tcpconnections_mrtg(char **reply, const char *reply_end) {
+  time_t t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker tcp4 stats, %lu conns/s :: %lu success/s.", total[OT_COUNTER_TCP_CONNECTIONS],
+                    total[OT_COUNTER_TCP_ANNOUNCES], (int)t, (int)(t / 3600), events_per_time(total[OT_COUNTER_TCP_CONNECTIONS], t),
+                    events_per_time(total[OT_COUNTER_TCP_ANNOUNCES], t));
+}
+
+static void stats_scrape_mrtg(char **reply, const char *reply_end) {
+  time_t t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker scrape stats, %lu scrape/s (tcp and udp)",
+                    total[OT_COUNTER_TCP_SCRAPES], total[OT_COUNTER_UDP_SCRAPES], (int)t, (int)(t / 3600),
+                    events_per_time((total[OT_COUNTER_TCP_SCRAPES] + total[OT_COUNTER_UDP_SCRAPES]), t));
+}
+
+static void stats_fullscrapes_mrtg(char **reply, const char *reply_end) {
+  ot_time t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker full scrape stats, %lu conns/s :: %lu bytes/s.",
+                    total[OT_COUNTER_FULLSCRAPES] * 1000, total[OT_COUNTER_FULLSCRAPE_BYTES], (int)t, (int)(t / 3600),
+                    events_per_time(total[OT_COUNTER_FULLSCRAPES], t),
+                    events_per_time(total[OT_COUNTER_FULLSCRAPE_BYTES], t));
+}
+
+static void stats_peers_mrtg(char **reply, const char *reply_end) {
+  torrent_stats stats = {0, 0, 0};
+
+  iterate_all_torrents(torrent_statter, (uintptr_t)&stats);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\nopentracker serving %llu torrents\nopentracker", stats.peer_count, stats.seed_count,
+                    stats.torrent_count);
+}
+
+static void stats_torrents_mrtg(char **reply, const char *reply_end) {
+  size_t torrent_count = mutex_get_torrent_count();
+
+  fmt_append(reply, reply_end, "%zd\n%zd\nopentracker serving %zd torrents\nopentracker", torrent_count, (size_t)0, torrent_count);
+}
+
+static void stats_httperrors_txt(char **reply, const char *reply_end) {
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "302 RED %llu\n400 ... %llu\n400 PAR %llu\n400 COM %llu\n403 IP  %llu\n404 INV %llu\n500 SRV %llu\n",
+                    total[OT_COUNTER_FAILED + 0], total[OT_COUNTER_FAILED + 1], total[OT_COUNTER_FAILED + 2], total[OT_COUNTER_FAILED + 3],
+                    total[OT_COUNTER_FAILED + 4], total[OT_COUNTER_FAILED + 5], total[OT_COUNTER_FAILED + 6]);
+}
+
+static void stats_return_renew_bucket(char **reply, const char *reply_end) {
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  int i;
+
+  for (i = 0; i < OT_PEER_TIMEOUT; ++i)
+    fmt_append(reply, reply_end, "%02i %llu\n", i, total[OT_COUNTER_RENEWED + i]);
+}
+
+static void stats_return_sync_mrtg(char **reply, const char *reply_end) {
+  ot_time t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker connections, %lu conns/s :: %lu success/s.", total[OT_COUNTER_SYNCS], 0LL,
+                    (int)t, (int)(t / 3600), events_per_time(total[OT_COUNTER_TCP_CONNECTIONS] + total[OT_COUNTER_UDP_CONNECTIONS], t),
+                    events_per_time(total[OT_COUNTER_TCP_ANNOUNCES] + total[OT_COUNTER_UDP_ANNOUNCES] + total[OT_COUNTER_UDP_CONNECTS], t));
+}
+
+static void stats_return_completed_mrtg(char **reply, const char *reply_end) {
+  ot_time t = time(NULL) - ot_start_time;
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+
+  fmt_append(reply, reply_end, "%llu\n%llu\n%i seconds (%i hours)\nopentracker, %lu completed/h.", total[OT_COUNTER_COMPLETED], 0LL, (int)t, (int)(t / 3600),
+                    events_per_time(total[OT_COUNTER_COMPLETED], t / 3600));
+}
+
+#ifdef WANT_LOG_NUMWANT
+extern unsigned long long numwants[201];
+static void             stats_return_numwants(char **reply, const char *reply_end) {
+  int i;
+  for (i = 0; i <= 200; ++i)
+    fmt_append(reply, reply_end, "%03d => %lld\n", i, numwants[i]);
+}
+#endif
+
+static void stats_return_everything(char **reply, const char *reply_end) {
+  unsigned long long total[OT_COUNTER_COUNT];
+
+  counters_total(total);
+
+  torrent_stats stats = {0, 0, 0};
+  int           i;
+
+  iterate_all_torrents(torrent_statter, (uintptr_t)&stats);
+
+  fmt_append(reply, reply_end, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
+  fmt_append(reply, reply_end, "<stats>\n");
+  fmt_append(reply, reply_end, "  <uptime>%llu</uptime>\n", (unsigned long long)(time(NULL) - ot_start_time));
+  fmt_append(reply, reply_end, "  <torrents>\n");
+  fmt_append(reply, reply_end, "    <count_mutex>%zd</count_mutex>\n", mutex_get_torrent_count());
+  fmt_append(reply, reply_end, "    <count_iterator>%llu</count_iterator>\n", stats.torrent_count);
+  fmt_append(reply, reply_end, "  </torrents>\n");
+  fmt_append(reply, reply_end, "  <peers>\n    <count>%llu</count>\n  </peers>\n", stats.peer_count);
+  fmt_append(reply, reply_end, "  <seeds>\n    <count>%llu</count>\n  </seeds>\n", stats.seed_count);
+  fmt_append(reply, reply_end, "  <completed>\n    <count>%llu</count>\n  </completed>\n", total[OT_COUNTER_COMPLETED]);
+  fmt_append(reply, reply_end, "  <connections>\n");
+  fmt_append(reply, reply_end, "    <tcp>\n      <accept>%llu</accept>\n      <announce>%llu</announce>\n      <scrape>%llu</scrape>\n    </tcp>\n",
+             total[OT_COUNTER_TCP_CONNECTIONS], total[OT_COUNTER_TCP_ANNOUNCES], total[OT_COUNTER_TCP_SCRAPES]);
+  fmt_append(reply, reply_end, "    <udp>\n      <overall>%llu</overall>\n      <connect>%llu</connect>\n      <announce>%llu</announce>\n      <scrape>%llu</scrape>\n      <missmatch>%llu</missmatch>\n    </udp>\n",
+             total[OT_COUNTER_UDP_CONNECTIONS], total[OT_COUNTER_UDP_CONNECTS], total[OT_COUNTER_UDP_ANNOUNCES], total[OT_COUNTER_UDP_SCRAPES],
+             total[OT_COUNTER_UDP_CONNID_MISSMATCH]);
+  fmt_append(reply, reply_end, "    <livesync>\n      <count>%llu</count>\n    </livesync>\n", total[OT_COUNTER_SYNCS]);
+  fmt_append(reply, reply_end, "  </connections>\n");
+  fmt_append(reply, reply_end, "  <debug>\n");
+  fmt_append(reply, reply_end, "    <renew>\n");
+  for (i = 0; i < OT_PEER_TIMEOUT; ++i)
+    fmt_append(reply, reply_end, "      <count interval=\"%02i\">%llu</count>\n", i, total[OT_COUNTER_RENEWED + i]);
+  fmt_append(reply, reply_end, "    </renew>\n");
+  fmt_append(reply, reply_end, "    <http_error>\n");
+  for (i = 0; i < CODE_HTTPERROR_COUNT; ++i)
+    fmt_append(reply, reply_end, "      <count code=\"%s\">%llu</count>\n", ot_failed_request_names[i], total[OT_COUNTER_FAILED + i]);
+  fmt_append(reply, reply_end, "    </http_error>\n");
+  fmt_append(reply, reply_end, "    <mutex_stall>\n      <count>%llu</count>\n    </mutex_stall>\n", total[OT_COUNTER_STALLS]);
+  fmt_append(reply, reply_end, "  </debug>\n");
+  fmt_append(reply, reply_end, "</stats>");
+}
+
+/* The names as the Makefile spells them, so that what a binary reports maps
+   straight back onto the FEATURES lines it was built from */
+static const char *const build_features[] = {
+#ifdef WANT_V4_ONLY
+    "WANT_V4_ONLY",
+#endif
+#ifdef WANT_ACCESSLIST_BLACK
+    "WANT_ACCESSLIST_BLACK",
+#endif
+#ifdef WANT_ACCESSLIST_WHITE
+    "WANT_ACCESSLIST_WHITE",
+#endif
+#ifdef WANT_DYNAMIC_ACCESSLIST
+    "WANT_DYNAMIC_ACCESSLIST",
+#endif
+#ifdef WANT_SYNC_LIVE
+    "WANT_SYNC_LIVE",
+#endif
+#ifdef WANT_IP_FROM_QUERY_STRING
+    "WANT_IP_FROM_QUERY_STRING",
+#endif
+#ifdef WANT_IP_FROM_PROXY
+    "WANT_IP_FROM_PROXY",
+#endif
+#ifdef WANT_COMPRESSION_GZIP
+    "WANT_COMPRESSION_GZIP",
+#endif
+#ifdef WANT_COMPRESSION_GZIP_ALWAYS
+    "WANT_COMPRESSION_GZIP_ALWAYS",
+#endif
+#ifdef WANT_COMPRESSION_ZSTD
+    "WANT_COMPRESSION_ZSTD",
+#endif
+#ifdef WANT_COMPRESSION_ZSTD_ALWAYS
+    "WANT_COMPRESSION_ZSTD_ALWAYS",
+#endif
+#ifdef WANT_FULLSCRAPE
+    "WANT_FULLSCRAPE",
+#endif
+#ifdef WANT_MODEST_FULLSCRAPES
+    "WANT_MODEST_FULLSCRAPES",
+#endif
+#ifdef WANT_KEEPALIVE
+    "WANT_KEEPALIVE",
+#endif
+#ifdef WANT_RESTRICT_STATS
+    "WANT_RESTRICT_STATS",
+#endif
+#ifdef WANT_LOG_NUMWANT
+    "WANT_LOG_NUMWANT",
+#endif
+#ifdef WANT_SPOT_WOODPECKER
+    "WANT_SPOT_WOODPECKER",
+#endif
+#ifdef WANT_SYSLOGS
+    "WANT_SYSLOGS",
+#endif
+#ifdef WANT_DEV_RANDOM
+    "WANT_DEV_RANDOM",
+#endif
+#ifdef WANT_INSECURE_RANDOM_FALLBACK
+    "WANT_INSECURE_RANDOM_FALLBACK",
+#endif
+#ifdef _DEBUG
+    "_DEBUG",
+#endif
+#ifdef _DEBUG_HTTPERROR
+    "_DEBUG_HTTPERROR",
+#endif
+#ifdef _DEBUG_RANDOMTORRENTS
+    "_DEBUG_RANDOMTORRENTS",
+#endif
+    NULL};
+
+void stats_return_tracker_features(char **reply, const char *reply_end) {
+  size_t i;
+
+  fmt_append(reply, reply_end, "events: %s\n", event_mechanism());
+  fmt_append(reply, reply_end, "features:");
+  for (i = 0; build_features[i]; ++i)
+    fmt_append(reply, reply_end, " %s", build_features[i]);
+  if (!build_features[0])
+    fmt_append(reply, reply_end, " none");
+  fmt_append(reply, reply_end, "\n");
+}
+
+void stats_return_tracker_version(char **reply, const char *reply_end) {
+  fmt_append(reply, reply_end, "opentracker %s", OT_VERSION);
+  if (*GIT_VERSION && strcmp(GIT_VERSION, OT_TAG))
+    fmt_append(reply, reply_end, " (%s)", GIT_VERSION);
+  fmt_append(reply, reply_end, "\n");
+  if (*OT_TAG)
+    fmt_append(reply, reply_end, "https://erdgeist.org/gitweb/opentracker/tag/?h=%s\n", OT_TAG);
+}
+
+void return_stats_for_tracker(char **reply, const char *reply_end, int mode, int format) {
+  (void)format;
+  switch (mode & TASK_TASK_MASK) {
+  case TASK_STATS_CONNS:
+    stats_connections_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_SCRAPE:
+    stats_scrape_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_UDP:
+    stats_udpconnections_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_TCP:
+    stats_tcpconnections_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_FULLSCRAPE:
+    stats_fullscrapes_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_COMPLETED:
+    stats_return_completed_mrtg(reply, reply_end);
+    break;
+  case TASK_STATS_HTTPERRORS:
+    stats_httperrors_txt(reply, reply_end);
+    break;
+  case TASK_STATS_RENEW:
+    stats_return_renew_bucket(reply, reply_end);
+    break;
+  case TASK_STATS_SYNCS:
+    stats_return_sync_mrtg(reply, reply_end);
+    break;
+#ifdef WANT_LOG_NUMWANT
+  case TASK_STATS_NUMWANTS:
+    stats_return_numwants(reply, reply_end);
+    break;
+#endif
+  default:
+    break;
+  }
+}
+
+static void stats_make(size_t *iovec_entries, struct iovec **iovector, ot_tasktype mode) {
+  char       *r;
+  const char *r_end;
+
+  *iovec_entries = 0;
+  *iovector      = NULL;
+  if (!(r = iovec_new_chunk(iovec_entries, iovector, OT_STATS_TMPSIZE)))
+    return;
+  r_end = r + OT_STATS_TMPSIZE;
+
+  switch (mode & TASK_TASK_MASK) {
+  case TASK_STATS_TORRENTS:
+    stats_torrents_mrtg(&r, r_end);
+    break;
+  case TASK_STATS_PEERS:
+    stats_peers_mrtg(&r, r_end);
+    break;
+  case TASK_STATS_SLASH24S:
+    stats_slash24s_txt(&r, r_end, 128);
+    break;
+  case TASK_STATS_TOP10:
+    stats_top_txt(&r, r_end, 10);
+    break;
+  case TASK_STATS_TOP100:
+    r = iovec_next_chunk(iovec_entries, iovector, r, 4 * OT_STATS_TMPSIZE);
+    if (!r)
+      return;
+    r_end = r + 4 * OT_STATS_TMPSIZE;
+    stats_top_txt(&r, r_end, 100);
+    break;
+  case TASK_STATS_EVERYTHING:
+    r = iovec_next_chunk(iovec_entries, iovector, r, OT_STATS_TMPSIZE + 64 * OT_PEER_TIMEOUT);
+    if (!r)
+      return;
+    r_end = r + OT_STATS_TMPSIZE + 64 * OT_PEER_TIMEOUT;
+    stats_return_everything(&r, r_end);
+    break;
+#ifdef WANT_SPOT_WOODPECKER
+  case TASK_STATS_WOODPECKERS:
+    stats_return_woodpeckers(&r, r_end, 128);
+    break;
+#endif
+  default:
+    iovec_free(iovec_entries, iovector);
+    return;
+  }
+  iovec_trim_last(iovec_entries, iovector, r);
+}
+
+void stats_issue_event(struct ot_workstruct *ws, ot_status_event event, PROTO_FLAG proto, uintptr_t event_data) {
+  if (!ws)
+    return;
+
+  switch (event) {
+  case EVENT_ACCEPT:
+    if (proto == FLAG_TCP)
+      COUNT(OT_COUNTER_TCP_CONNECTIONS, 1);
+    else
+      COUNT(OT_COUNTER_UDP_CONNECTIONS, 1);
+    break;
+  case EVENT_ANNOUNCE:
+    if (proto == FLAG_TCP)
+      COUNT(OT_COUNTER_TCP_ANNOUNCES, 1);
+    else
+      COUNT(OT_COUNTER_UDP_ANNOUNCES, 1);
+    break;
+  case EVENT_CONNECT:
+    if (proto == FLAG_TCP)
+      COUNT(OT_COUNTER_TCP_CONNECTS, 1);
+    else
+      COUNT(OT_COUNTER_UDP_CONNECTS, 1);
+    break;
+  case EVENT_COMPLETED:
+#ifdef WANT_SYSLOGS
+    {
+      char                  timestring[64];
+      char                  hash_hex[42], peerid_hex[42], ip_readable[64];
+      struct tm             time_now;
+      time_t                ttt;
+
+      time(&ttt);
+      localtime_r(&ttt, &time_now);
+      strftime(timestring, sizeof(timestring), "%FT%T%z", &time_now);
+
+      hex_from_hash(hash_hex, *ws->hash);
+      if (ws->peer_id)
+        hex_from_hash(peerid_hex, (uint8_t *)ws->peer_id);
+      else {
+        *peerid_hex = 0;
+      }
+
+      ip_readable[ip_format(ip_readable, (char *)&ws->peer)] = 0;
+      syslog(LOG_INFO, "time=%s event=completed info_hash=%s peer_id=%s ip=%s", timestring, hash_hex, peerid_hex, ip_readable);
+    }
+#endif
+    COUNT(OT_COUNTER_COMPLETED, 1);
+    break;
+  case EVENT_SCRAPE:
+    if (proto == FLAG_TCP)
+      COUNT(OT_COUNTER_TCP_SCRAPES, 1);
+    else
+      COUNT(OT_COUNTER_UDP_SCRAPES, 1);
+    break;
+  case EVENT_FULLSCRAPE:
+    COUNT(OT_COUNTER_FULLSCRAPES, 1);
+    COUNT(OT_COUNTER_FULLSCRAPE_BYTES, event_data);
+    break;
+  case EVENT_FULLSCRAPE_REQUEST: {
+    ot_ip6 *ip = (ot_ip6 *)event_data; /* ugly hack to transfer ip to stats */
+    char    _debug[512];
+    int     off  = snprintf(_debug, sizeof(_debug), "[%08d] scrp:  ", (unsigned int)(time_now_seconds() - ot_start_time) / 60);
+    off         += ip_format(_debug + off, *ip);
+    off         += snprintf(_debug + off, sizeof(_debug) - off, " - FULL SCRAPE\n");
+    (void)write(2, _debug, off);
+    COUNT(OT_COUNTER_FULLSCRAPE_REQUESTS, 1);
+  } break;
+  case EVENT_FULLSCRAPE_REQUEST_GZIP: {
+    ot_ip6 *ip = (ot_ip6 *)event_data; /* ugly hack to transfer ip to stats */
+    char    _debug[512];
+    int     off  = snprintf(_debug, sizeof(_debug), "[%08d] scrp:  ", (unsigned int)(time_now_seconds() - ot_start_time) / 60);
+    off         += ip_format(_debug + off, *ip);
+    off         += snprintf(_debug + off, sizeof(_debug) - off, " - FULL SCRAPE\n");
+    (void)write(2, _debug, off);
+    COUNT(OT_COUNTER_FULLSCRAPE_REQUESTS, 1);
+  } break;
+  case EVENT_FAILED:
+    COUNT(OT_COUNTER_FAILED + event_data, 1);
+    break;
+  case EVENT_RENEW:
+    COUNT(OT_COUNTER_RENEWED + event_data, 1);
+    break;
+  case EVENT_SYNC:
+    COUNT(OT_COUNTER_SYNCS, event_data);
+    break;
+  case EVENT_BUCKET_LOCKED:
+    COUNT(OT_COUNTER_STALLS, 1);
+    break;
+#ifdef WANT_SPOT_WOODPECKER
+  case EVENT_WOODPECKER:
+    pthread_mutex_lock(&g_woodpeckers_mutex);
+    stat_increase_network_count(&stats_woodpeckers_tree, 0, event_data);
+    pthread_mutex_unlock(&g_woodpeckers_mutex);
+    break;
+#endif
+  case EVENT_CONNID_MISSMATCH:
+    COUNT(OT_COUNTER_UDP_CONNID_MISSMATCH, 1);
+  default:
+    break;
+  }
+}
+
+void stats_cleanup(void) {
+#ifdef WANT_SPOT_WOODPECKER
+  pthread_mutex_lock(&g_woodpeckers_mutex);
+  stats_shift_down_network_count(&stats_woodpeckers_tree, 0, 1);
+  pthread_mutex_unlock(&g_woodpeckers_mutex);
+#endif
+}
+
+static void *stats_worker(void *args) {
+  size_t        iovec_entries;
+  struct iovec *iovector;
+
+  (void)args;
+
+  while (g_opentracker_running) {
+    ot_tasktype tasktype = TASK_STATS;
+    ot_taskid   taskid   = workqueue_poptask(&tasktype);
+    if (!taskid)
+      break;
+    stats_make(&iovec_entries, &iovector, tasktype);
+    if (workqueue_pushresult(taskid, iovec_entries, iovector))
+      iovec_free(&iovec_entries, &iovector);
+  }
+  return NULL;
+}
+
+void stats_deliver(int64_t sock, int tasktype) { workqueue_pushtask(sock, tasktype); }
+
+static pthread_t thread_id;
+void stats_init(void) {
+  ot_start_time = time_now_seconds();
+  pthread_create(&thread_id, NULL, stats_worker, NULL);
+}
+
+void stats_deinit(void) {
+  workqueue_wakeall();
+  pthread_join(thread_id, NULL);
+}
diff --git a/src/ot_stats.h b/src/ot_stats.h
new file mode 100644
index 0000000..45a547e
--- /dev/null
+++ b/src/ot_stats.h
@@ -0,0 +1,40 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_STATS_H__
+#define OT_STATS_H__
+
+#include "trackerlogic.h"
+
+typedef enum {
+  EVENT_ACCEPT,
+  EVENT_READ,
+  EVENT_CONNECT, /* UDP only */
+  EVENT_ANNOUNCE,
+  EVENT_COMPLETED,
+  EVENT_RENEW,
+  EVENT_SYNC,
+  EVENT_SCRAPE,
+  EVENT_FULLSCRAPE_REQUEST,
+  EVENT_FULLSCRAPE_REQUEST_GZIP,
+  EVENT_FULLSCRAPE_REQUEST_ZSTD,
+  EVENT_FULLSCRAPE, /* TCP only */
+  EVENT_FAILED,
+  EVENT_BUCKET_LOCKED,
+  EVENT_WOODPECKER,
+  EVENT_CONNID_MISSMATCH
+} ot_status_event;
+
+void               stats_counters_register(struct ot_workstruct *ws);
+void               stats_counters_retire(struct ot_workstruct *ws);
+
+void               stats_issue_event(struct ot_workstruct *ws, ot_status_event event, PROTO_FLAG proto, uintptr_t event_data);
+void               stats_deliver(int64_t sock, int tasktype);
+void               stats_cleanup(void);
+void               return_stats_for_tracker(char **reply, const char *reply_end, int mode, int format);
+void               stats_return_tracker_version(char **reply, const char *reply_end);
+void               stats_return_tracker_features(char **reply, const char *reply_end);
+void               stats_init(void);
+void               stats_deinit(void);
+
+#endif
diff --git a/src/ot_tcp.c b/src/ot_tcp.c
new file mode 100644
index 0000000..1351b92
--- /dev/null
+++ b/src/ot_tcp.c
@@ -0,0 +1,180 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_batch.h"
+#include "ot_buf.h"
+#include "ot_event.h"
+#include "ot_fdstate.h"
+#include "ot_http.h"
+#include "ot_mutex.h"
+#include "ot_socket.h"
+#include "ot_worker.h"
+#include "ot_stats.h"
+#include "ot_tcp.h"
+#include "trackerlogic.h"
+
+static ssize_t header_complete(char *request, ssize_t byte_count) {
+  ssize_t i = 0, state = 0;
+
+  for (i = 1; i < byte_count; i += 2)
+    if (request[i] <= 13) {
+      i--;
+      for (state = 0; i < byte_count; ++i) {
+        char c = request[i];
+        if (c == '\r' || c == '\n')
+          state = (state >> 2) | ((c << 6) & 0xc0);
+        else
+          break;
+        if (state >= 0xa0 || state == 0x99)
+          return i + 1;
+      }
+    }
+  return 0;
+}
+
+void tcp_read(const int64_t sock, struct ot_workstruct *ws) {
+  struct http_data *cookie     = fdstate_cookie(sock);
+  ssize_t           byte_count = read((int)sock, ws->inbuf, G_INBUF_SIZE);
+
+  if (byte_count == 0 || (byte_count == -1 && errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR)) {
+    http_close(sock);
+    return;
+  }
+
+  if (byte_count == -1)
+    return;
+
+  ws->request      = NULL;
+  ws->request_size = 0;
+  ws->header_size  = 0;
+  ws->keep_alive   = 0;
+
+  /* If we get the whole request in one packet, handle it without copying */
+  if (!cookie->request.data) {
+    if ((ws->header_size = header_complete(ws->inbuf, byte_count))) {
+      ws->request      = ws->inbuf;
+      ws->request_size = byte_count;
+      http_handle_request(sock, ws);
+    } else if (buf_cat(&cookie->request, ws->inbuf, (size_t)byte_count))
+      http_close(sock);
+    return;
+  }
+
+  if (buf_cat(&cookie->request, ws->inbuf, (size_t)byte_count) || cookie->request.size > G_INBUF_SIZE) {
+    http_issue_error(sock, ws, CODE_HTTPERROR_500);
+    return;
+  }
+
+  while ((ws->header_size = header_complete(cookie->request.data, (ssize_t)cookie->request.size))) {
+    ws->request      = cookie->request.data;
+    ws->request_size = (ssize_t)cookie->request.size;
+    http_handle_request(sock, ws);
+#ifdef WANT_KEEPALIVE
+    if (!ws->keep_alive)
+#endif
+      return;
+  }
+}
+
+void tcp_write(const int64_t sock) {
+  struct http_data *cookie     = fdstate_cookie(sock);
+  int               chunked    = 0;
+  int               keep_alive = 0;
+
+  if (cookie) {
+    chunked    = (cookie->flag & STRUCT_HTTP_FLAG_CHUNKED_IN_TRANSFER) != 0;
+    keep_alive = (cookie->flag & STRUCT_HTTP_FLAG_KEEPALIVE) != 0;
+
+    if (cookie->batch) {
+      if (batch_send(sock, cookie->batch) == BATCH_FAILED) {
+        http_close(sock);
+        return;
+      }
+      if (batch_pending(cookie->batch))
+        return;
+    }
+  }
+
+  /* In a chunked transfer, wait for the next piece once everything queued has gone out */
+  if (chunked)
+    http_interest_set(sock, cookie, 0);
+  else if (keep_alive) {
+    /* The reply is out and the client asked to keep the connection, so go
+       back to waiting for the next request */
+    http_interest_set(sock, cookie, EVENT_IN);
+    fdstate_set_expiry(sock, time_future_seconds(OT_CLIENT_TIMEOUT));
+  } else
+    http_close(sock);
+}
+
+/* The fast path, assuming that the complete request has usually arrived by the time a
+   connection is accepted, so it is answered here outside the event loop. The more load
+   a tracker has, the more likely it is that by the time it accepts, the roundtrip to
+   the peer has completed.
+   If the request could not be completely handled, the stack cookie is promoted to heap
+   and the connection handed over to the event loop to finish */
+void tcp_accept(const int64_t serversocket, struct ot_workstruct *ws) {
+  int64_t  sock;
+  ot_ip6   ip;
+  uint16_t port;
+
+  while ((sock = socket_accept(serversocket, ip, &port)) != -1) {
+    struct http_data cookie;
+    uint32_t         generation;
+
+    memset(&cookie, 0, sizeof(cookie));
+    memcpy(cookie.ip, ip, sizeof(ot_ip6));
+    cookie.interest = EVENT_IN;
+    cookie.flag     = STRUCT_HTTP_FLAG_ONSTACK;
+
+    generation = fdstate_open(sock, &cookie, time_future_seconds(OT_CLIENT_TIMEOUT));
+    if (!fdstate_claim((int)sock, generation)) {
+      fdstate_close(sock);
+      event_close((int)sock);
+      continue;
+    }
+
+    stats_issue_event(ws, EVENT_ACCEPT, FLAG_TCP, (uintptr_t)ip);
+
+    tcp_read(sock, ws);
+
+    /* Gone already if it was answered and closed inline */
+    if (fdstate_generation((int)sock) != generation)
+      continue;
+
+    /* Handling it may already have given it a heap home and handed it to
+       another thread, and then it is no longer this frame's to touch */
+    if (fdstate_cookie((int)sock) != &cookie)
+      fdstate_release((int)sock);
+    else if (!http_adopt(sock))
+      http_close(sock);
+    else
+      fdstate_release((int)sock);
+  }
+}
+
+/* A worker blocks in accept and nowhere else: the connection it is handed is
+   non blocking, so a client that stops talking is given to the event loop
+   rather than keeping this thread. */
+static void tcp_run(struct ot_worker *me) {
+  while (g_opentracker_running)
+    tcp_accept(me->sock, &me->ws);
+}
+
+void tcp_worker_install(int64_t sock) {
+  socket_set_blocking((int)sock, 1);
+  socket_defer_accept((int)sock);
+
+  if (worker_start(tcp_run, sock) == -1)
+    fprintf(stderr, "Warning: could not install a tcp worker, this socket stays with the workers already running.\n");
+}
diff --git a/src/ot_tcp.h b/src/ot_tcp.h
new file mode 100644
index 0000000..afed142
--- /dev/null
+++ b/src/ot_tcp.h
@@ -0,0 +1,24 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_TCP_H__
+#define OT_TCP_H__
+
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+/* Take whatever connections are waiting on a listening socket and answer
+   them, each on this thread's stack, handing a connection that cannot be
+   finished to the event loop */
+void tcp_accept(const int64_t serversocket, struct ot_workstruct *ws);
+
+/* Handler connections in the event loop has become readable or writable */
+void tcp_read(const int64_t sock, struct ot_workstruct *ws);
+void tcp_write(const int64_t sock);
+
+/* One thread accepting on one socket. Called once per worker. */
+void tcp_worker_install(int64_t sock);
+
+
+#endif
diff --git a/src/ot_udp.c b/src/ot_udp.c
new file mode 100644
index 0000000..644b71d
--- /dev/null
+++ b/src/ot_udp.c
@@ -0,0 +1,226 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_ip.h"
+#include "ot_random.h"
+#include "ot_rijndael.h"
+#include "ot_socket.h"
+#include "ot_worker.h"
+#include "ot_stats.h"
+#include "ot_udp.h"
+#include "trackerlogic.h"
+
+static uint32_t g_rijndael_round_key[44] = {0};
+static volatile uint32_t g_key_of_the_hour[2] = {0};
+static volatile ot_time  g_hour_of_the_key;
+
+
+static void     udp_generate_rijndael_round_key(void) {
+  uint32_t key[16];
+  random_bytes(key, sizeof(key));
+  rijndaelKeySetupEnc128(g_rijndael_round_key, (uint8_t *)key);
+
+  g_key_of_the_hour[0] = random_uint32();
+  g_hour_of_the_key = time_now_minutes();
+}
+
+/* Generate current and previous connection id for ip */
+static void udp_make_connectionid(uint32_t connid[2], const ot_ip6 remoteip, int age) {
+  uint32_t plain[4], crypt[4];
+  int      i;
+  uint32_t current_key_of_the_hour;
+
+  if (time_now_minutes() - g_hour_of_the_key >= 60) {
+    uint32_t old_key_of_the_hour = g_key_of_the_hour[0];
+    uint32_t new_key_of_the_hour = random_uint32();
+    /* If in the meantime another thread has performed
+       key rotation, do not overwrite their results */
+    if (time_now_minutes() - g_hour_of_the_key >= 60) {
+      /* Upgrade en bloc */
+      g_hour_of_the_key    = time_now_minutes();
+      g_key_of_the_hour[0] = new_key_of_the_hour;
+      g_key_of_the_hour[1] = old_key_of_the_hour;
+    }
+  }
+
+  memcpy(plain, remoteip, sizeof(plain));
+  current_key_of_the_hour = g_key_of_the_hour[age];
+  for (i = 0; i < 4; ++i)
+    plain[i] ^= current_key_of_the_hour;
+  rijndaelEncrypt128(g_rijndael_round_key, (uint8_t *)plain, (uint8_t *)crypt);
+  connid[0] = crypt[0] ^ crypt[1];
+  connid[1] = crypt[2] ^ crypt[3];
+}
+
+/* UDP implementation according to http://xbtt.sourceforge.net/udp_tracker_protocol.html */
+int handle_udp6(int64_t serversocket, struct ot_workstruct *ws) {
+  ot_ip6    remoteip;
+  uint32_t *inpacket  = (uint32_t *)ws->inbuf;
+  uint32_t *outpacket = (uint32_t *)ws->outbuf;
+  uint32_t  left, event;
+  uint32_t  connid[2];
+  uint32_t  action;
+  uint16_t  port, remoteport;
+  size_t    byte_count, scrape_count;
+
+  ssize_t   result = socket_recv(serversocket, ws->inbuf, G_INBUF_SIZE, remoteip, &remoteport);
+  if (result <= 0)
+    return 0;
+  byte_count = (size_t)result;
+
+  stats_issue_event(ws, EVENT_ACCEPT, FLAG_UDP, (uintptr_t)remoteip);
+  stats_issue_event(ws, EVENT_READ, FLAG_UDP, byte_count);
+
+  /* Minimum udp tracker packet size, also catches error */
+  if (byte_count < 16)
+    return 1;
+
+  /* Get action to take. Ignore error messages and broken packets */
+  action = ntohl(inpacket[2]);
+  if (action > 2)
+    return 1;
+
+  /* Generate the connection id we give out and expect to and from
+     the requesting ip address, this prevents udp spoofing */
+  udp_make_connectionid(connid, remoteip, 0);
+
+  /* Initialise hash pointer */
+  ws->hash    = NULL;
+  ws->peer_id = NULL;
+
+  /* If action is not 0 (connect), then we expect the derived
+     connection id in first 64 bit */
+  if ((action > 0) && (inpacket[0] != connid[0] || inpacket[1] != connid[1])) {
+    /* If connection id does not match, try the one that was
+       valid in the previous hour. Only if this also does not
+       match, return an error packet */
+    udp_make_connectionid(connid, remoteip, 1);
+    if (inpacket[0] != connid[0] || inpacket[1] != connid[1]) {
+      const char err_idmiss[] = "Connection ID missmatch.";
+      size_t s = sizeof(err_idmiss);
+      outpacket[0]   = htonl(3);
+      outpacket[1]   = inpacket[3];
+      memcpy(&outpacket[2], &err_idmiss[0], s);
+      socket_send(serversocket, ws->outbuf, 8 + s, remoteip, remoteport);
+      stats_issue_event(ws, EVENT_CONNID_MISSMATCH, FLAG_UDP, 8 + s);
+      return 1;
+    }
+  }
+
+  switch (action) {
+  case 0: /* This is a connect action */
+    /* look for udp bittorrent magic id */
+    if ((ntohl(inpacket[0]) != 0x00000417) || (ntohl(inpacket[1]) != 0x27101980))
+      return 1;
+
+    outpacket[0] = 0;
+    outpacket[1] = inpacket[3];
+    outpacket[2] = connid[0];
+    outpacket[3] = connid[1];
+
+    socket_send(serversocket, ws->outbuf, 16, remoteip, remoteport);
+    stats_issue_event(ws, EVENT_CONNECT, FLAG_UDP, 16);
+    break;
+  case 1: /* This is an announce action */
+    /* Minimum udp announce packet size */
+    if (byte_count < 98)
+      return 1;
+
+    /* We do only want to know, if it is zero */
+    left     = inpacket[64 / 4] | inpacket[68 / 4];
+
+    event    = ntohl(inpacket[80 / 4]);
+    port     = *(uint16_t *)(((char *)inpacket) + 96);
+    ws->hash = (ot_hash *)(((char *)inpacket) + 16);
+
+    OT_SETIP(ws->peer, remoteip);
+    OT_SETPORT(ws->peer, &port);
+    OT_PEERFLAG(ws->peer) = 0;
+
+    switch (event) {
+    case 1:
+      OT_PEERFLAG(ws->peer) |= PEER_FLAG_COMPLETED;
+      break;
+    case 3:
+      OT_PEERFLAG(ws->peer) |= PEER_FLAG_STOPPED;
+      break;
+    default:
+      break;
+    }
+
+    if (!left)
+      OT_PEERFLAG(ws->peer) |= PEER_FLAG_SEEDING;
+
+    outpacket[0] = htonl(1); /* announce action */
+    outpacket[1] = inpacket[12 / 4];
+
+    if (OT_PEERFLAG(ws->peer) & PEER_FLAG_STOPPED) { /* Peer is gone. */
+      ws->reply      = ws->outbuf;
+      ws->reply_size = remove_peer_from_torrent(FLAG_UDP, ws);
+    } else {
+      /* Limit amount of peers to OT_MAX_PEERS_UDP */
+      uint32_t numwant   = ntohl(inpacket[92 / 4]);
+      size_t   max_peers = ip_is_v4mapped(remoteip) ? OT_MAX_PEERS_UDP4 : OT_MAX_PEERS_UDP6;
+      if (numwant > max_peers)
+        numwant = max_peers;
+
+      ws->reply      = ws->outbuf + 8;
+      ws->reply_size = add_peer_to_torrent_and_return_peers(FLAG_UDP, ws, numwant);
+
+      if (!ws->reply_size) {
+        const char err_unauth[] = "Requested download is not authorized for use with this tracker.";
+        size_t s = sizeof(err_unauth);
+        outpacket[0]  = htonl(3);
+        memcpy(&outpacket[2], &err_unauth[0], s);
+        socket_send(serversocket, ws->outbuf, 8 + s, remoteip, remoteport);
+        return 1;
+      }
+      ws->reply_size += 8;
+    }
+
+    socket_send(serversocket, ws->outbuf, ws->reply_size, remoteip, remoteport);
+    stats_issue_event(ws, EVENT_ANNOUNCE, FLAG_UDP, ws->reply_size);
+    break;
+
+  case 2:                    /* This is a scrape action */
+    outpacket[0] = htonl(2); /* scrape action */
+    outpacket[1] = inpacket[12 / 4];
+
+    for (scrape_count = 0; (scrape_count * 20 < byte_count - 16) && (scrape_count <= 74); scrape_count++)
+      return_udp_scrape_for_torrent(*(ot_hash *)(((char *)inpacket) + 16 + 20 * scrape_count), ((char *)outpacket) + 8 + 12 * scrape_count);
+
+    socket_send(serversocket, ws->outbuf, 8 + 12 * scrape_count, remoteip, remoteport);
+    stats_issue_event(ws, EVENT_SCRAPE, FLAG_UDP, scrape_count);
+    break;
+  }
+  return 1;
+}
+
+static void udp_run(struct ot_worker *me) {
+  while (g_opentracker_running)
+    handle_udp6(me->sock, &me->ws);
+}
+
+void udp_init(void) {
+  if (!g_rijndael_round_key[0])
+    udp_generate_rijndael_round_key();
+}
+
+void udp_worker_install(int64_t sock) {
+#ifdef _DEBUG
+  fprintf(stderr, "Installing a worker on udp socket %ld\n", (unsigned long)sock);
+#endif
+  socket_set_blocking((int)sock, 1);
+
+  if (worker_start(udp_run, sock) == -1)
+    fprintf(stderr, "Warning: could not install a udp worker, this socket stays with the workers already running.\n");
+}
diff --git a/src/ot_udp.h b/src/ot_udp.h
new file mode 100644
index 0000000..2710744
--- /dev/null
+++ b/src/ot_udp.h
@@ -0,0 +1,17 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_UDP_H__
+#define OT_UDP_H__
+
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+void udp_init(void);
+/* One thread reading one socket. Called once per worker. */
+void udp_worker_install(int64_t sock);
+
+int  handle_udp6(int64_t serversocket, struct ot_workstruct *ws);
+
+#endif
diff --git a/src/ot_urlencoded.c b/src/ot_urlencoded.c
new file mode 100644
index 0000000..4109bb5
--- /dev/null
+++ b/src/ot_urlencoded.c
@@ -0,0 +1,168 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* Opentracker */
+#include "ot_urlencoded.h"
+
+/* System */
+#include <string.h>
+
+/* Idea is to do a in place replacement or guarantee at least
+   strlen( string ) bytes in deststring
+   watch http://www.ietf.org/rfc/rfc2396.txt
+         unreserved    = alphanum | mark
+         mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
+   we add '%' to the matrix to not stop at encoded chars.
+   After losing too many requests to being too strict, add the following characters to reserved matrix
+         relax         = "+" | "," | "/" | ";" | "<" | ">" | ":"
+*/
+
+/* This matrix holds for each ascii character the information,
+   whether it is a non-terminating character for one of the three
+   scan states we are in, that is 'path', 'param' and 'value' from
+  /path?param=value&param=value, it is encoded in bit 0, 1 and 2
+  respectively
+
+  The top bit of lower nibble indicates, whether this character is
+  a hard terminator, ie. \0, \n or \s, where the whole scanning
+  process should terminate
+  */
+static const unsigned char is_unreserved[256] = {
+  8,0,0,0,0,0,0,0,0,0,8,0,0,8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+  8,7,8,8,8,7,0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,4,7,6,
+  4,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,7,
+  8,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,7,0,
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+};
+
+/* Do a fast nibble to hex representation conversion */
+static unsigned char fromhex(unsigned char x) {
+  x -= '0';
+  if (x <= 9)
+    return x;
+  x &= ~0x20;
+  x -= 'A' - '0';
+  if (x < 6)
+    return x + 10;
+  return 0xff;
+}
+
+/* Skip the value of a param=value pair */
+void urlencoded_skip_value(char **string) {
+  const unsigned char *s = *(const unsigned char **)string;
+  unsigned char        f;
+
+  /* Since we are asked to skip the 'value', we assume to stop at
+     terminators for a 'value' string position */
+  while ((f = is_unreserved[*s++]) & SCAN_SEARCHPATH_VALUE)
+    ;
+
+  /* If we stopped at a hard terminator like \0 or \n, make the
+     next urlencoded_parse encounter it again */
+  if (f & SCAN_SEARCHPATH_TERMINATOR)
+    --s;
+
+  *string = (char *)s;
+}
+
+int urlencoded_match_keyword(const ot_keywords *keywords, char **string, SCAN_SEARCHPATH_FLAG flags) {
+  char   *deststring   = *string;
+  ssize_t match_length = urlencoded_parse(string, deststring, flags);
+
+  if (match_length < 0)
+    return match_length;
+  if (match_length == 0)
+    return -3;
+
+  while (keywords->key) {
+    if (!strncmp(keywords->key, deststring, match_length) && !keywords->key[match_length])
+      return keywords->value;
+    keywords++;
+  }
+
+  return -3;
+}
+
+ssize_t urlencoded_parse(char **string, char *deststring, SCAN_SEARCHPATH_FLAG flags) {
+  const unsigned char *s = *(const unsigned char **)string;
+  unsigned char       *d = (unsigned char *)deststring;
+  unsigned char        b, c;
+
+  /* This is the main decoding loop.
+    'flag' determines, which characters are non-terminating in current context
+    (ie. stop at '=' and '&' if scanning for a 'param'; stop at '?' if scanning for the path )
+  */
+  while (is_unreserved[c = *s++] & flags) {
+
+    /* When encountering an url escaped character, try to decode */
+    if (c == '%') {
+      if ((b = fromhex(*s++)) == 0xff)
+        return -1;
+      if ((c = fromhex(*s++)) == 0xff)
+        return -1;
+      c |= (b << 4);
+    }
+
+    /* Write (possibly decoded) character to output */
+    *d++ = c;
+  }
+
+  switch (c) {
+  case 0:
+  case '\r':
+  case '\n':
+  case ' ':
+    /* If we started scanning on a hard terminator, indicate we've finished */
+    if (d == (unsigned char *)deststring)
+      return -2;
+
+    /* Else make the next call to urlencoded_parse encounter it again */
+    --s;
+    break;
+  case '?':
+    if (flags != SCAN_PATH)
+      return -1;
+    break;
+  case '=':
+    if (flags != SCAN_SEARCHPATH_PARAM)
+      return -1;
+    break;
+  case '&':
+    if (flags == SCAN_PATH)
+      return -1;
+    if (flags == SCAN_SEARCHPATH_PARAM)
+      --s;
+    break;
+  default:
+    return -1;
+  }
+
+  *string = (char *)s;
+  return d - (unsigned char *)deststring;
+}
+
+
+size_t urlencoded_format(char *dest, const uint8_t *src, size_t len) {
+  static const char safe[]     = "$/.=~-_";
+  static const char hexdigit[] = "0123456789abcdef";
+  size_t            written    = 0, i;
+
+  for (i = 0; i < len; ++i) {
+    uint8_t c = src[i];
+
+    /* strchr would find the terminator, so a zero byte never counts as safe */
+    if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || (c && strchr(safe, c))) {
+      dest[written++] = (char)c;
+    } else {
+      dest[written]     = '%';
+      dest[written + 1] = hexdigit[c >> 4];
+      dest[written + 2] = hexdigit[c & 15];
+      written          += 3;
+    }
+  }
+
+  return written;
+}
diff --git a/src/ot_urlencoded.h b/src/ot_urlencoded.h
new file mode 100644
index 0000000..9882468
--- /dev/null
+++ b/src/ot_urlencoded.h
@@ -0,0 +1,53 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef SCAN_URLENCODED_QUERY_H__
+#define SCAN_URLENCODED_QUERY_H__
+
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+typedef struct {
+  const char *key;
+  int         value;
+} ot_keywords;
+
+typedef enum {
+  SCAN_PATH                  = 1,
+  SCAN_SEARCHPATH_PARAM      = 2,
+  SCAN_SEARCHPATH_VALUE      = 4,
+  SCAN_SEARCHPATH_TERMINATOR = 8
+} SCAN_SEARCHPATH_FLAG;
+
+/* string     in: pointer to source
+              out: pointer to next scan position
+   deststring pointer to destination
+   flags      determines, what to parse
+   returns    number of valid converted characters in deststring
+              or -1 for parse error
+              or -2 for terminator found
+*/
+ssize_t urlencoded_parse(char **string, char *deststring, SCAN_SEARCHPATH_FLAG flags);
+
+/* string     in: pointer to source
+              out: pointer to next scan position
+   flags      determines, what to parse
+   returns    value for matched keyword
+              or -1 for parse error
+              or -2 for terminator found
+              or -3 for no keyword matched
+ */
+int     urlencoded_match_keyword(const ot_keywords *keywords, char **string, SCAN_SEARCHPATH_FLAG flags);
+
+/* string     in: pointer to value of a param=value pair to skip
+              out: pointer to next scan position on return
+*/
+void    urlencoded_skip_value(char **string);
+
+
+/* The other direction: percent encode len bytes from src into dest and return
+   how many characters were written. dest needs room for three times len. */
+size_t  urlencoded_format(char *dest, const uint8_t *src, size_t len);
+
+#endif
diff --git a/src/ot_vector.c b/src/ot_vector.c
new file mode 100644
index 0000000..ab0566c
--- /dev/null
+++ b/src/ot_vector.c
@@ -0,0 +1,287 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* Opentracker */
+#include "trackerlogic.h"
+
+static int vector_compare_peer6(const void *peer1, const void *peer2) { return memcmp(peer1, peer2, OT_PEER_COMPARE_SIZE6); }
+static int vector_compare_peer4(const void *peer1, const void *peer2) { return memcmp(peer1, peer2, OT_PEER_COMPARE_SIZE4); }
+
+/* This function gives us a binary search that returns a pointer, even if
+   no exact match is found. In that case it sets exactmatch 0 and gives
+   calling functions the chance to insert data
+*/
+void *vector_binary_search(const void *const key, const void *base, const size_t member_count, const size_t member_size, size_t compare_size, int *exactmatch) {
+  size_t interval = member_count;
+
+  while (interval) {
+    uint8_t *lookat = ((uint8_t *)base) + member_size * (interval / 2);
+    int      cmp    = memcmp(lookat, key, compare_size);
+    if (cmp == 0) {
+      base = lookat;
+      break;
+    }
+    if (cmp < 0) {
+      base = lookat + member_size;
+      interval--;
+    }
+    interval /= 2;
+  }
+
+  *exactmatch = interval;
+  return (void *)base;
+}
+
+static uint8_t vector_hash_peer(ot_peer const *peer, size_t compare_size, size_t bucket_count) {
+  unsigned int hash = 5381;
+  uint8_t     *p    = (uint8_t *)peer;
+  while (compare_size--)
+    hash += (hash << 5) + *(p++);
+  return hash % bucket_count;
+}
+
+/* This is the generic insert operation for our vector type.
+   It tries to locate the object at "key" with size "member_size" by comparing its first "compare_size" bytes with
+   those of objects in vector. Our special "vector_binary_search" function does that and either returns the match or a
+   pointer to where the object is to be inserted. vector_find_or_insert makes space for the object and copies it,
+   if it wasn't found in vector. Caller needs to check the passed "exactmatch" variable to see, whether an insert
+   took place. If resizing the vector failed, NULL is returned, else the pointer to the object in vector.
+*/
+void *vector_find_or_insert(ot_vector *vector, void *key, size_t member_size, size_t compare_size, int *exactmatch) {
+  uint8_t *match = vector_binary_search(key, vector->data, vector->size, member_size, compare_size, exactmatch);
+  size_t   match_offset, bytes_after;
+
+  if (*exactmatch)
+    return match;
+
+  /* Hold the insertion point as an offset rather than a pointer: it survives
+     the realloc below, and an empty vector has no data pointer to offset from
+     in the first place */
+  match_offset = vector->size ? (size_t)(match - (uint8_t *)vector->data) : 0;
+  bytes_after  = member_size * vector->size - match_offset;
+
+  if (vector->size + 1 > vector->space) {
+    size_t   new_space = vector->space ? OT_VECTOR_GROW_RATIO * vector->space : OT_VECTOR_MIN_MEMBERS;
+    uint8_t *new_data  = realloc(vector->data, new_space * member_size);
+
+    if (!new_data)
+      return NULL;
+
+    vector->data  = new_data;
+    vector->space = new_space;
+  }
+
+  match = (uint8_t *)vector->data + match_offset;
+  memmove(match + member_size, match, bytes_after);
+
+  vector->size++;
+  return match;
+}
+
+ot_peer *vector_find_or_insert_peer(ot_vector *vector, ot_peer const *peer, size_t peer_size, int *exactmatch) {
+  ot_peer     *match;
+  const size_t compare_size = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
+  size_t       match_offset, bytes_after;
+
+  /* If space is zero but size is set, we're dealing with a list of vector->size buckets */
+  if (vector->space < vector->size)
+    vector = ((ot_vector *)vector->data) + vector_hash_peer(peer, compare_size, vector->size);
+  match = vector_binary_search(peer, vector->data, vector->size, peer_size, compare_size, exactmatch);
+
+  if (*exactmatch)
+    return match;
+
+  /* Hold the insertion point as an offset rather than a pointer: it survives
+     the realloc below, and an empty vector has no data pointer to offset from
+     in the first place. bytes_after is what has to move up by peer_size to
+     make room for the new peer */
+  match_offset = vector->size ? (size_t)(match - (ot_peer *)vector->data) : 0;
+  bytes_after  = vector->size * peer_size - match_offset;
+
+  if (vector->size + 1 > vector->space) {
+    size_t   new_space = vector->space ? OT_VECTOR_GROW_RATIO * vector->space : OT_VECTOR_MIN_MEMBERS;
+    ot_peer *new_data  = realloc(vector->data, new_space * peer_size);
+
+    if (!new_data)
+      return NULL;
+
+    vector->data  = new_data;
+    vector->space = new_space;
+  }
+
+  match = (ot_peer *)vector->data + match_offset;
+  memmove(match + peer_size, match, bytes_after);
+
+  vector->size++;
+  return match;
+}
+
+/* This is the non-generic delete from vector-operation specialized for peers in pools.
+   It returns 0 if no peer was found (and thus not removed)
+              1 if a non-seeding peer was removed
+              2 if a seeding peer was removed
+*/
+int vector_remove_peer(ot_vector *vector, ot_peer const *peer, size_t peer_size) {
+  int      exactmatch, was_seeder;
+  ot_peer *match, *end;
+  size_t   compare_size = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
+
+  if (!vector->size)
+    return 0;
+
+  /* If space is zero but size is set, we're dealing with a list of vector->size buckets */
+  if (vector->space < vector->size)
+    vector = ((ot_vector *)vector->data) + vector_hash_peer(peer, compare_size, vector->size);
+
+  end   = ((ot_peer *)vector->data) + peer_size * vector->size;
+  match = (ot_peer *)vector_binary_search(peer, vector->data, vector->size, peer_size, compare_size, &exactmatch);
+  if (!exactmatch)
+    return 0;
+
+  was_seeder = (OT_PEERFLAG_D(match, peer_size) & PEER_FLAG_SEEDING) ? 2 : 1;
+  memmove(match, match + peer_size, end - match - peer_size);
+
+  vector->size--;
+  vector_fixup_peers(vector, peer_size);
+  return was_seeder;
+}
+
+void vector_remove_torrent(ot_vector *vector, ot_torrent *match) {
+  ot_torrent *end;
+
+  if (!vector->size)
+    return;
+
+  end = ((ot_torrent *)vector->data) + vector->size;
+
+  free_peerlist(match->peer_list6);
+  free_peerlist(match->peer_list4);
+
+  memmove(match, match + 1, sizeof(ot_torrent) * (end - match - 1));
+  if ((--vector->size * OT_VECTOR_SHRINK_THRESH < vector->space) && (vector->space >= OT_VECTOR_SHRINK_RATIO * OT_VECTOR_MIN_MEMBERS)) {
+    vector->space /= OT_VECTOR_SHRINK_RATIO;
+    vector->data   = realloc(vector->data, vector->space * sizeof(ot_torrent));
+  }
+}
+
+void vector_clean_list(ot_vector *vector, size_t num_buckets) {
+  while (num_buckets--)
+    free(vector[num_buckets].data);
+  free(vector);
+  return;
+}
+
+void vector_redistribute_buckets(ot_peerlist *peer_list, size_t peer_size) {
+  size_t     bucket, bucket_size_new, num_buckets_new, num_buckets_old = 1;
+  ot_vector *bucket_list_new, *bucket_list_old = &peer_list->peers;
+  int (*sort_func)(const void *, const void *) = peer_size == OT_PEER_SIZE6 ? &vector_compare_peer6 : &vector_compare_peer4;
+
+  if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+    num_buckets_old = peer_list->peers.size;
+    bucket_list_old = peer_list->peers.data;
+  }
+
+  if (peer_list->peer_count < 255)
+    num_buckets_new = 1;
+  else if (peer_list->peer_count > 8192)
+    num_buckets_new = 64;
+  else if (peer_list->peer_count >= 512 && peer_list->peer_count < 4096)
+    num_buckets_new = 16;
+  else if (peer_list->peer_count < 512 && num_buckets_old <= 16)
+    num_buckets_new = num_buckets_old;
+  else if (peer_list->peer_count < 512)
+    num_buckets_new = 1;
+  else if (peer_list->peer_count < 8192 && num_buckets_old > 1)
+    num_buckets_new = num_buckets_old;
+  else
+    num_buckets_new = 16;
+
+  if (num_buckets_new == num_buckets_old)
+    return;
+
+  /* Assume near perfect distribution */
+  bucket_list_new = calloc(1, num_buckets_new * sizeof(ot_vector));
+  if (!bucket_list_new)
+    return;
+
+  bucket_size_new = OT_VECTOR_MIN_MEMBERS;
+  while (bucket_size_new * num_buckets_new < peer_list->peer_count)
+    bucket_size_new *= OT_VECTOR_GROW_RATIO;
+
+  /* preallocate vectors to hold all peers */
+  for (bucket = 0; bucket < num_buckets_new; ++bucket) {
+    bucket_list_new[bucket].space = bucket_size_new;
+    bucket_list_new[bucket].data  = malloc(bucket_size_new * peer_size);
+    if (!bucket_list_new[bucket].data) {
+      vector_clean_list(bucket_list_new, num_buckets_new);
+      return;
+    }
+  }
+
+  /* Now sort them into the correct bucket */
+  for (bucket = 0; bucket < num_buckets_old; ++bucket) {
+    ot_peer *peers_old      = bucket_list_old[bucket].data;
+    size_t   peer_count_old = bucket_list_old[bucket].size;
+    while (peer_count_old--) {
+      ot_vector *bucket_dest = bucket_list_new;
+      if (num_buckets_new > 1)
+        bucket_dest += vector_hash_peer(peers_old, OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size), num_buckets_new);
+      if (bucket_dest->size + 1 > bucket_dest->space) {
+        void *tmp = realloc(bucket_dest->data, peer_size * OT_VECTOR_GROW_RATIO * bucket_dest->space);
+        if (!tmp) {
+          vector_clean_list(bucket_list_new, num_buckets_new);
+          return;
+        }
+        bucket_dest->data   = tmp;
+        bucket_dest->space *= OT_VECTOR_GROW_RATIO;
+      }
+      memcpy((ot_peer *)bucket_dest->data + peer_size * bucket_dest->size++, peers_old, peer_size);
+      peers_old += peer_size;
+    }
+  }
+
+  /* Now sort each bucket to later allow bsearch */
+  for (bucket = 0; bucket < num_buckets_new; ++bucket)
+    qsort(bucket_list_new[bucket].data, bucket_list_new[bucket].size, peer_size, sort_func);
+
+  /* Everything worked fine. Now link new bucket_list to peer_list */
+  if (OT_PEERLIST_HASBUCKETS(peer_list))
+    vector_clean_list((ot_vector *)peer_list->peers.data, peer_list->peers.size);
+  else
+    free(peer_list->peers.data);
+
+  if (num_buckets_new > 1) {
+    peer_list->peers.data  = bucket_list_new;
+    peer_list->peers.size  = num_buckets_new;
+    peer_list->peers.space = 0; /* Magic marker for "is list of buckets" */
+  } else {
+    peer_list->peers.data  = bucket_list_new->data;
+    peer_list->peers.size  = bucket_list_new->size;
+    peer_list->peers.space = bucket_list_new->space;
+    free(bucket_list_new);
+  }
+}
+
+void vector_fixup_peers(ot_vector *vector, size_t peer_size) {
+  int need_fix = 0;
+
+  if (!vector->size) {
+    free(vector->data);
+    vector->data  = NULL;
+    vector->space = 0;
+    return;
+  }
+
+  while ((vector->size * OT_VECTOR_SHRINK_THRESH < vector->space) && (vector->space >= OT_VECTOR_SHRINK_RATIO * OT_VECTOR_MIN_MEMBERS)) {
+    vector->space /= OT_VECTOR_SHRINK_RATIO;
+    need_fix++;
+  }
+  if (need_fix)
+    vector->data = realloc(vector->data, vector->space * peer_size);
+}
diff --git a/src/ot_vector.h b/src/ot_vector.h
new file mode 100644
index 0000000..8a5ba86
--- /dev/null
+++ b/src/ot_vector.h
@@ -0,0 +1,39 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_VECTOR_H__
+#define OT_VECTOR_H__
+
+#include <stddef.h>
+
+/* These defines control vectors behaviour */
+#define OT_VECTOR_MIN_MEMBERS   2
+#define OT_VECTOR_GROW_RATIO    2
+#define OT_VECTOR_SHRINK_THRESH 4
+#define OT_VECTOR_SHRINK_RATIO  2
+
+#define OT_PEER_BUCKET_MINCOUNT 512
+#define OT_PEER_BUCKET_MAXCOUNT 256
+
+typedef struct {
+  void  *data;
+  size_t size;
+  size_t space;
+} ot_vector;
+
+/* trackerlogic.h needs ot_vector, break circular dependency here */
+#include "trackerlogic.h"
+
+void    *vector_binary_search(const void *const key, const void *base, const size_t member_count, const size_t member_size, size_t compare_size, int *exactmatch);
+void    *vector_find_or_insert(ot_vector *vector, void *key, size_t member_size, size_t compare_size, int *exactmatch);
+ot_peer *vector_find_or_insert_peer(ot_vector *vector, ot_peer const *peer, size_t peer_size, int *exactmatch);
+
+int      vector_remove_peer(ot_vector *vector, ot_peer const *peer, size_t peer_size);
+void     vector_remove_torrent(ot_vector *vector, ot_torrent *match);
+
+/* For ot_clean.c */
+void     vector_redistribute_buckets(ot_peerlist *peer_list, size_t peer_size);
+void     vector_fixup_peers(ot_vector *vector, size_t peer_size);
+void     vector_clean_list(ot_vector *vector, size_t num_buckets);
+
+#endif
diff --git a/src/ot_worker.c b/src/ot_worker.c
new file mode 100644
index 0000000..432d272
--- /dev/null
+++ b/src/ot_worker.c
@@ -0,0 +1,73 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_worker.h"
+#include "trackerlogic.h"
+
+static struct ot_worker **g_workers;
+static size_t             g_worker_count;
+
+/* Everything a worker needs doing around its own loop, in one place, so that
+   a new kind of worker cannot miss a piece of it. */
+static void *worker_trampoline(void *args) {
+  struct ot_worker *me = args;
+
+  if (workstruct_init(&me->ws) == -1)
+    fprintf(stderr, "Warning: a worker could not get its buffers and will not run.\n");
+  else {
+    me->run(me);
+    workstruct_deinit(&me->ws);
+  }
+
+  atomic_store(&me->left, 1);
+  return NULL;
+}
+
+int worker_start(ot_worker_run run, int64_t sock) {
+  struct ot_worker **grown = realloc(g_workers, (g_worker_count + 1) * sizeof(*g_workers));
+  struct ot_worker  *worker;
+
+  if (!grown)
+    return -1;
+  g_workers = grown;
+
+  if (!(worker = calloc(1, sizeof(*worker))))
+    return -1;
+  worker->sock = sock;
+  worker->run  = run;
+
+  if (pthread_create(&worker->thread, NULL, worker_trampoline, worker)) {
+    free(worker);
+    return -1;
+  }
+  g_workers[g_worker_count++] = worker;
+  return 0;
+}
+
+void worker_stop_all(void) {
+  size_t i;
+
+  for (i = 0; i < g_worker_count; ++i) {
+    struct ot_worker *worker = g_workers[i];
+
+    /* Repeated because a signal only interrupts a call already under way */
+    while (!atomic_load(&worker->left)) {
+      pthread_kill(worker->thread, OT_SIGNAL_WAKE);
+      usleep(1000);
+    }
+    pthread_join(worker->thread, NULL);
+    free(worker);
+  }
+
+  free(g_workers);
+  g_workers      = NULL;
+  g_worker_count = 0;
+}
diff --git a/src/ot_worker.h b/src/ot_worker.h
new file mode 100644
index 0000000..4954773
--- /dev/null
+++ b/src/ot_worker.h
@@ -0,0 +1,37 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_WORKER_H__
+#define OT_WORKER_H__
+
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdint.h>
+
+#include "trackerlogic.h"
+
+struct ot_worker;
+
+/* What a worker does between being started and being told to stop. It reads
+   worker->sock and works out of worker->ws; everything around it, from the
+   buffers to the counters to saying goodbye, is handled here. */
+typedef void (*ot_worker_run)(struct ot_worker *worker);
+
+/* A thread that serves requests on a socket of its own, with the buffers and
+   counters it needs. Each is allocated on its own, so taking on another one
+   never moves the record a running worker holds. */
+struct ot_worker {
+  pthread_t            thread;
+  _Atomic int          left;
+  int64_t              sock;
+  ot_worker_run        run;
+  struct ot_workstruct ws;
+};
+
+/* Start one. Returns -1 if it could not be started. */
+int  worker_start(ot_worker_run run, int64_t sock);
+
+/* Wake every worker until it has left, then join it */
+void worker_stop_all(void);
+
+#endif
diff --git a/src/ot_workqueue.c b/src/ot_workqueue.c
new file mode 100644
index 0000000..56a7cd2
--- /dev/null
+++ b/src/ot_workqueue.c
@@ -0,0 +1,241 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_iovec.h"
+#include "ot_workqueue.h"
+#include "trackerlogic.h"
+
+/* Pushing a result wakes the thread that will send it */
+extern int g_self_pipe[2];
+
+struct ot_task {
+  ot_taskid       taskid;
+  ot_tasktype     tasktype;
+  int64_t         sock;
+  size_t          iovec_entries;
+  struct iovec   *iovec;
+  struct ot_task *next;
+};
+
+static ot_taskid       next_free_taskid = 1;
+static struct ot_task *tasklist;
+static pthread_mutex_t tasklist_mutex;
+static pthread_cond_t  tasklist_being_filled;
+
+int workqueue_pushtask(int64_t sock, ot_tasktype tasktype) {
+  struct ot_task **tmptask, *task;
+
+  task = malloc(sizeof(struct ot_task));
+  if (!task)
+    return -1;
+
+  task->taskid        = 0;
+  task->tasktype      = tasktype;
+  task->sock          = sock;
+  task->iovec_entries = 0;
+  task->iovec         = NULL;
+  task->next          = 0;
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  /* Skip to end of list */
+  tmptask = &tasklist;
+  while (*tmptask)
+    tmptask = &(*tmptask)->next;
+  *tmptask = task;
+
+  /* Inform waiting workers and release lock */
+  pthread_cond_broadcast(&tasklist_being_filled);
+  pthread_mutex_unlock(&tasklist_mutex);
+  return 0;
+}
+
+void workqueue_canceltask(int64_t sock) {
+  struct ot_task **task;
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  for (task = &tasklist; *task; task = &((*task)->next))
+    if ((*task)->sock == sock) {
+      struct iovec   *iovec = (*task)->iovec;
+      struct ot_task *ptask = *task;
+      size_t                   i;
+
+      /* Free task's iovec, the buffers it points at and the vector itself */
+      for (i = 0; i < (*task)->iovec_entries; ++i)
+        free(iovec[i].iov_base);
+      free(iovec);
+
+      *task = (*task)->next;
+      free(ptask);
+      break;
+    }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+}
+
+ot_taskid workqueue_poptask(ot_tasktype *tasktype) {
+  struct ot_task *task;
+  ot_taskid       taskid = 0;
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  while (!taskid) {
+    /* Skip to the first unassigned task this worker wants to do */
+    for (task = tasklist; task; task = task->next)
+      if (!task->taskid && (TASK_CLASS_MASK & task->tasktype) == *tasktype) {
+        /* If we found an outstanding task, assign a taskid to it
+           and leave the loop */
+        task->taskid = taskid = ++next_free_taskid;
+        *tasktype             = task->tasktype;
+        break;
+      }
+
+    /* Wait until the next task is being fed, unless the tracker is on its
+       way out, in which case the worker is meant to leave rather than wait */
+    if (!taskid) {
+      if (!g_opentracker_running)
+        break;
+      pthread_cond_wait(&tasklist_being_filled, &tasklist_mutex);
+    }
+  }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+
+  return taskid;
+}
+
+void workqueue_pushsuccess(ot_taskid taskid) {
+  struct ot_task **task;
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  for (task = &tasklist; *task; task = &((*task)->next))
+    if ((*task)->taskid == taskid) {
+      struct ot_task *ptask = *task;
+      *task = (*task)->next;
+      free(ptask);
+      break;
+    }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+}
+
+int workqueue_pushresult(ot_taskid taskid, size_t iovec_entries, struct iovec *iovec) {
+  struct ot_task *task;
+  const char      byte = 'o';
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  for (task = tasklist; task; task = task->next)
+    if (task->taskid == taskid) {
+      task->iovec_entries = iovec_entries;
+      task->iovec         = iovec;
+      task->tasktype      = TASK_DONE;
+      break;
+    }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+
+  /* A full pipe has already done this nudge's job, so a failure is fine */
+  (void)!write(g_self_pipe[1], &byte, 1);
+
+  /* Indicate whether the worker has to throw away results */
+  return task ? 0 : -1;
+}
+
+int workqueue_pushchunked(ot_taskid taskid, struct iovec *iovec) {
+  struct ot_task *task;
+  const char      byte = 'o';
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  for (task = tasklist; task; task = task->next)
+    if (task->taskid == taskid) {
+      if (iovec) {
+        if (iovec_append(&task->iovec_entries, &task->iovec, iovec))
+          task->tasktype = TASK_DONE_PARTIAL;
+        else
+          task = NULL;
+      } else
+        task->tasktype = TASK_DONE;
+      break;
+    }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+
+  /* A full pipe has already done this nudge's job, so a failure is fine */
+  (void)!write(g_self_pipe[1], &byte, 1);
+
+  /* Indicate whether the worker has to throw away results */
+  return task ? 0 : -1;
+}
+
+int64_t workqueue_popresult(size_t *iovec_entries, struct iovec **iovec, int *is_partial) {
+  struct ot_task **task;
+  int64_t sock = -1;
+
+  *is_partial = 0;
+
+  /* Want exclusive access to tasklist */
+  pthread_mutex_lock(&tasklist_mutex);
+
+  for (task = &tasklist; *task; task = &((*task)->next))
+    if (((*task)->tasktype & TASK_CLASS_MASK) == TASK_DONE) {
+      struct ot_task *ptask = *task;
+      *iovec_entries        = ptask->iovec_entries;
+      *iovec                = ptask->iovec;
+      sock                  = ptask->sock;
+
+      if ((*task)->tasktype == TASK_DONE) {
+        *task = ptask->next;
+        free(ptask);
+      } else {
+        ptask->iovec_entries = 0;
+        ptask->iovec         = NULL;
+        *is_partial          = 1;
+        /* Prevent task from showing up immediately again unless new data was added */
+        (*task)->tasktype    = TASK_FULLSCRAPE;
+      }
+      break;
+    }
+
+  /* Release lock */
+  pthread_mutex_unlock(&tasklist_mutex);
+  return sock;
+}
+
+void workqueue_wakeall(void) {
+  pthread_mutex_lock(&tasklist_mutex);
+  pthread_cond_broadcast(&tasklist_being_filled);
+  pthread_mutex_unlock(&tasklist_mutex);
+}
+
+void workqueue_init(void) {
+  pthread_mutex_init(&tasklist_mutex, NULL);
+  pthread_cond_init(&tasklist_being_filled, NULL);
+}
+
+void workqueue_deinit(void) {
+  pthread_mutex_destroy(&tasklist_mutex);
+  pthread_cond_destroy(&tasklist_being_filled);
+}
diff --git a/src/ot_workqueue.h b/src/ot_workqueue.h
new file mode 100644
index 0000000..82ae29b
--- /dev/null
+++ b/src/ot_workqueue.h
@@ -0,0 +1,74 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_WORKQUEUE_H__
+#define OT_WORKQUEUE_H__
+
+#include <stdint.h>
+#include <sys/uio.h>
+
+#include "trackerlogic.h"
+
+/* Work the tracker hands to a thread of its own: a full scrape or an
+   expensive stats page, which take too long to build while a client waits.
+   The task goes in here, the reply comes back out. */
+
+typedef enum {
+  TASK_STATS_CONNS               = 0x0001,
+  TASK_STATS_TCP                 = 0x0002,
+  TASK_STATS_UDP                 = 0x0003,
+  TASK_STATS_SCRAPE              = 0x0004,
+  TASK_STATS_FULLSCRAPE          = 0x0005,
+  TASK_STATS_TPB                 = 0x0006,
+  TASK_STATS_HTTPERRORS          = 0x0007,
+  TASK_STATS_RENEW               = 0x000a,
+  TASK_STATS_SYNCS               = 0x000b,
+  TASK_STATS_COMPLETED           = 0x000c,
+  TASK_STATS_NUMWANTS            = 0x000d,
+
+  TASK_STATS                     = 0x0100, /* Mask */
+  TASK_STATS_TORRENTS            = 0x0101,
+  TASK_STATS_PEERS               = 0x0102,
+  TASK_STATS_SLASH24S            = 0x0103,
+  TASK_STATS_TOP10               = 0x0104,
+  TASK_STATS_TOP100              = 0x0105,
+  TASK_STATS_EVERYTHING          = 0x0106,
+  TASK_STATS_WOODPECKERS         = 0x0108,
+
+  TASK_FULLSCRAPE                = 0x0200, /* Default mode */
+  TASK_FULLSCRAPE_TPB_BINARY     = 0x0201,
+  TASK_FULLSCRAPE_TPB_ASCII      = 0x0202,
+  TASK_FULLSCRAPE_TPB_ASCII_PLUS = 0x0203,
+  TASK_FULLSCRAPE_TPB_URLENCODED = 0x0204,
+  TASK_FULLSCRAPE_TRACKERSTATE   = 0x0205,
+
+  TASK_DMEM                      = 0x0300,
+
+  TASK_DONE                      = 0x0f00,
+  TASK_DONE_PARTIAL              = 0x0f01,
+
+  TASK_FLAG_GZIP                 = 0x1000,
+  TASK_FLAG_BZIP2                = 0x2000,
+  TASK_FLAG_ZSTD                 = 0x4000,
+  TASK_FLAG_CHUNKED              = 0x8000,
+
+  TASK_TASK_MASK                 = 0x0fff,
+  TASK_CLASS_MASK                = 0x0f00,
+  TASK_FLAGS_MASK                = 0xf000
+} ot_tasktype;
+
+typedef unsigned long ot_taskid;
+
+int        workqueue_pushtask(int64_t sock, ot_tasktype tasktype);
+void       workqueue_canceltask(int64_t sock);
+void       workqueue_pushsuccess(ot_taskid taskid);
+ot_taskid  workqueue_poptask(ot_tasktype *tasktype);
+int        workqueue_pushresult(ot_taskid taskid, size_t iovec_entries, struct iovec *iovector);
+int        workqueue_pushchunked(ot_taskid taskid, struct iovec *iovec);
+int64_t    workqueue_popresult(size_t *iovec_entries, struct iovec **iovector, int *is_partial);
+
+void       workqueue_init(void);
+void       workqueue_deinit(void);
+void       workqueue_wakeall(void);
+
+#endif
diff --git a/src/proxy.c b/src/proxy.c
new file mode 100644
index 0000000..8589db5
--- /dev/null
+++ b/src/proxy.c
@@ -0,0 +1,871 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* This relays sync traffic between trackers, and between multicast domains
+   that have no route to each other, so that no tracker has to reach out to
+   the outside world by itself. Defunc. */
+
+/* System */
+#include <arpa/inet.h>
+#include <ctype.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Libowfat */
+#include "io.h"
+
+/* Opentracker */
+#include "ot_batch.h"
+#include "ot_fdstate.h"
+#include "ot_ip.h"
+#include "ot_mutex.h"
+#include "ot_random.h"
+#include "ot_scan.h"
+#include "ot_socket.h"
+#include "ot_stats.h"
+#include "ot_vector.h"
+#include "trackerlogic.h"
+
+#include "ot_livesync.h"
+
+ot_ip6   g_serverip;
+uint16_t g_serverport = 9009;
+uint32_t g_tracker_id;
+ot_ip6     groupip_1 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 224, 0, 23, 5};
+int      g_self_pipe[2];
+
+/* If you have more than 10 peers, don't use this proxy
+   Use 20 slots for 10 peers to have room for 10 incoming connection slots
+ */
+#define MAX_PEERS                         20
+
+#define LIVESYNC_INCOMING_BUFFSIZE        (256 * 256)
+#define STREAMSYNC_OUTGOING_BUFFSIZE      (256 * 256)
+
+#define LIVESYNC_OUTGOING_BUFFSIZE_PEERS  1480
+#define LIVESYNC_OUTGOING_WATERMARK_PEERS (sizeof(ot_peer) + sizeof(ot_hash))
+#define LIVESYNC_MAXDELAY                 15 /* seconds */
+
+/* The amount of time a complete sync cycle should take */
+#define OT_SYNC_INTERVAL_MINUTES          2
+
+/* So after each bucket wait 1 / OT_BUCKET_COUNT intervals */
+#define OT_SYNC_SLEEP                     (((OT_SYNC_INTERVAL_MINUTES) * 60 * 1000000) / (OT_BUCKET_COUNT))
+
+enum { OT_SYNC_PEER4, OT_SYNC_PEER6 };
+enum { FLAG_SERVERSOCKET = 1 };
+
+/* For incoming packets */
+static int      g_socket_in = -1;
+static uint8_t  g_inbuffer[LIVESYNC_INCOMING_BUFFSIZE];
+
+/* For outgoing packets */
+static int      g_socket_out = -1;
+static uint8_t  g_peerbuffer_start[LIVESYNC_OUTGOING_BUFFSIZE_PEERS];
+static uint8_t *g_peerbuffer_pos;
+static uint8_t *g_peerbuffer_highwater = g_peerbuffer_start + LIVESYNC_OUTGOING_BUFFSIZE_PEERS - LIVESYNC_OUTGOING_WATERMARK_PEERS;
+static ot_time  g_next_packet_time;
+
+static void *livesync_worker(void *args);
+static void *streamsync_worker(void *args);
+static void livesync_proxytell(uint8_t prefix, uint8_t *info_hash, uint8_t *peer);
+
+void exerr(const char *message) {
+  fprintf(stderr, "%s\n", message);
+  exit(111);
+}
+
+void stats_issue_event(struct ot_workstruct *ws, ot_status_event event, PROTO_FLAG proto, uintptr_t event_data) {
+  (void)ws;
+  (void)event;
+  (void)proto;
+  (void)event_data;
+}
+
+void livesync_bind_mcast(ot_ip6 ip, uint16_t port) {
+  if (!ip_is_v4mapped(ip))
+    exerr("v6 mcast support not yet available.");
+
+  if (g_socket_in != -1)
+    exerr("Error: Livesync listen ip specified twice.");
+
+  if ((g_socket_in = socket_mcast_join(groupip_1, ip, port)) == -1)
+    exerr("Error: Cant bind live sync incoming socket.");
+
+  if ((g_socket_out = socket_mcast_bind(ip, port, 1)) == -1)
+    exerr("Error: Cant bind live sync outgoing socket.");
+}
+
+size_t add_peer_to_torrent_proxy(ot_hash hash, ot_peer *peer, size_t peer_size) {
+  int          exactmatch;
+  ot_torrent  *torrent;
+  ot_peerlist *peer_list;
+  ot_peer     *peer_dest;
+  ot_vector   *torrents_list = mutex_bucket_lock_by_hash(hash);
+  size_t       compare_size  = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
+
+  torrent                    = vector_find_or_insert(torrents_list, (void *)hash, sizeof(ot_torrent), compare_size, &exactmatch);
+  if (!torrent)
+    return -1;
+
+  if (!exactmatch) {
+    /* Create a new torrent entry, then */
+    memcpy(torrent->hash, hash, sizeof(ot_hash));
+
+    if (!(torrent->peer_list6 = malloc(sizeof(ot_peerlist))) || !(torrent->peer_list4 = malloc(sizeof(ot_peerlist)))) {
+      vector_remove_torrent(torrents_list, torrent);
+      mutex_bucket_unlock_by_hash(hash, 0);
+      return -1;
+    }
+
+    memset(torrent->peer_list6, 0, sizeof(ot_peerlist));
+    memset(torrent->peer_list4, 0, sizeof(ot_peerlist));
+  }
+
+  peer_list = peer_size == OT_PEER_SIZE6 ? torrent->peer_list6 : torrent->peer_list4;
+
+  /* Check for peer in torrent */
+  peer_dest = vector_find_or_insert_peer(&(peer_list->peers), peer, peer_size, &exactmatch);
+  if (!peer_dest) {
+    mutex_bucket_unlock_by_hash(hash, 0);
+    return -1;
+  }
+  /* Tell peer that it's fresh */
+  OT_PEERTIME(peer, peer_size) = 0;
+
+  /* If we hadn't had a match create peer there */
+  if (!exactmatch) {
+    peer_list->peer_count++;
+    if (OT_PEERFLAG_D(peer, peer_size) & PEER_FLAG_SEEDING)
+      peer_list->seed_count++;
+  }
+  memcpy(peer_dest, peer, peer_size);
+  mutex_bucket_unlock_by_hash(hash, 0);
+  return 0;
+}
+
+size_t remove_peer_from_torrent_proxy(ot_hash hash, ot_peer *peer, size_t peer_size) {
+  int         exactmatch;
+  ot_vector  *torrents_list = mutex_bucket_lock_by_hash(hash);
+  ot_torrent *torrent       = vector_binary_search(hash, torrents_list->data, torrents_list->size, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+
+  if (exactmatch) {
+    ot_peerlist *peer_list = peer_list = peer_size == OT_PEER_SIZE6 ? torrent->peer_list6 : torrent->peer_list4;
+    switch (vector_remove_peer(&peer_list->peers, peer, peer_size)) {
+    case 2:
+      peer_list->seed_count--; /* Intentional fallthrough */
+    case 1:
+      peer_list->peer_count--; /* Intentional fallthrough */
+    default:
+      break;
+    }
+  }
+
+  mutex_bucket_unlock_by_hash(hash, 0);
+  return 0;
+}
+
+void free_peerlist(ot_peerlist *peer_list) {
+  if (peer_list->peers.data) {
+    if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+      ot_vector *bucket_list = (ot_vector *)(peer_list->peers.data);
+
+      while (peer_list->peers.size--)
+        free(bucket_list++->data);
+    }
+    free(peer_list->peers.data);
+  }
+  free(peer_list);
+}
+
+static void livesync_handle_peersync(ssize_t datalen, size_t peer_size) {
+  int off = sizeof(g_tracker_id) + sizeof(uint32_t);
+
+  fprintf(stderr, ".");
+
+  while ((ssize_t)(off + sizeof(ot_hash) + peer_size) <= datalen) {
+    ot_peer *peer = (ot_peer *)(g_inbuffer + off + sizeof(ot_hash));
+    ot_hash *hash = (ot_hash *)(g_inbuffer + off);
+
+    if (OT_PEERFLAG_D(peer, peer_size) & PEER_FLAG_STOPPED)
+      remove_peer_from_torrent_proxy(*hash, peer, peer_size);
+    else
+      add_peer_to_torrent_proxy(*hash, peer, peer_size);
+
+    off += sizeof(ot_hash) + peer_size;
+  }
+}
+
+int usage(char *self) {
+  fprintf(stderr, "Usage: %s -L <livesync_iface_ip> -l <listenip>:<listenport> -c <connectip>:<connectport>\n", self);
+  return 0;
+}
+
+enum {
+  FLAG_OUTGOING      = 0x80,
+
+  FLAG_DISCONNECTED  = 0x00,
+  FLAG_CONNECTING    = 0x01,
+  FLAG_WAITTRACKERID = 0x02,
+  FLAG_CONNECTED     = 0x03,
+
+  FLAG_MASK          = 0x07
+};
+
+#define PROXYPEER_NEEDSCONNECT(flag)     ((flag) == FLAG_OUTGOING)
+#define PROXYPEER_ISCONNECTED(flag)      (((flag) & FLAG_MASK) == FLAG_CONNECTED)
+#define PROXYPEER_SETDISCONNECTED(flag)  (flag) = (((flag) & FLAG_OUTGOING) | FLAG_DISCONNECTED)
+#define PROXYPEER_SETCONNECTING(flag)    (flag) = (((flag) & FLAG_OUTGOING) | FLAG_CONNECTING)
+#define PROXYPEER_SETWAITTRACKERID(flag) (flag) = (((flag) & FLAG_OUTGOING) | FLAG_WAITTRACKERID)
+#define PROXYPEER_SETCONNECTED(flag)     (flag) = (((flag) & FLAG_OUTGOING) | FLAG_CONNECTED)
+
+typedef struct {
+  int      state;             /* Whether we want to connect, how far our handshake is, etc. */
+  ot_ip6   ip;                /* The peer to connect to */
+  uint16_t port;              /* The peers port */
+  uint8_t  indata[8192 * 16]; /* Any data not processed yet */
+  size_t   indata_length;     /* Length of unprocessed data */
+  uint32_t tracker_id;        /* How the other end greeted */
+  int64_t  fd;                /* A file handle, if connected, <= 0 is disconnected (0 initially, -1 else) */
+  ot_batch outdata;           /* The batch containing our sync data */
+
+  size_t   packet_tcount;     /* Number of unprocessed torrents in packet we currently receive */
+  uint8_t  packet_tprefix;    /* Prefix byte for all torrents in current packet */
+  uint8_t  packet_type;       /* Type of current packet */
+  uint32_t packet_tid;        /* Tracker id for current packet */
+
+} proxy_peer;
+static void process_indata(proxy_peer *peer);
+
+void reset_info_block(proxy_peer *peer) {
+  peer->indata_length = 0;
+  peer->tracker_id    = 0;
+  peer->fd            = -1;
+  peer->packet_tcount = 0;
+  batch_reset(&peer->outdata);
+  PROXYPEER_SETDISCONNECTED(peer->state);
+}
+
+/* Number of connections to peers
+ * If a peer's IP is set, we try to reconnect, when the connection drops
+ * If we already have a connected tracker_id in our records for an _incoming_ connection, drop it
+ * Multiple connections to/from the same ip are okay, if tracker_id doesn't match
+ * Reconnect attempts occur only twice a minute
+ */
+static size_t     g_connection_count;
+static ot_time    g_connection_reconn;
+static proxy_peer g_connections[MAX_PEERS];
+
+static void handle_reconnects(void) {
+  size_t i;
+  for (i = 0; i < g_connection_count; ++i)
+    if (PROXYPEER_NEEDSCONNECT(g_connections[i].state)) {
+      int64_t newfd = socket_tcp_connect(g_serverip, g_serverport, g_connections[i].ip, g_connections[i].port);
+      fprintf(stderr, "(Re)connecting to peer...");
+      if (newfd == -1)
+        continue; /* No socket for you */
+      io_fd(newfd);
+      io_wantwrite(newfd); /* So we will be informed when it is connected */
+      fdstate_open(newfd, g_connections + i, 0);
+
+      /* Prepare connection info block */
+      reset_info_block(g_connections + i);
+      g_connections[i].fd = newfd;
+      PROXYPEER_SETCONNECTING(g_connections[i].state);
+    }
+  g_connection_reconn = time(NULL) + 30;
+}
+
+/* Handle incoming connection requests, check against whitelist */
+static void handle_accept(int64_t serversocket) {
+  int64_t newfd;
+  ot_ip6  ip;
+  uint16_t port;
+
+  while ((newfd = socket_accept(serversocket, ip, &port)) != -1) {
+
+    /* XXX some access control */
+
+    /* Put fd into a non-blocking mode */
+    io_nonblock(newfd);
+
+    if (!io_fd(newfd))
+      io_close(newfd);
+    else {
+      /* Find a new home for our incoming connection */
+      int i;
+      for (i = 0; i < MAX_PEERS; ++i)
+        if (g_connections[i].state == FLAG_DISCONNECTED)
+          break;
+      if (i == MAX_PEERS) {
+        fprintf(stderr, "No room for incoming connection.");
+        close(newfd);
+        continue;
+      }
+
+      /* Prepare connection info block */
+      reset_info_block(g_connections + i);
+      PROXYPEER_SETCONNECTING(g_connections[i].state);
+      g_connections[i].port = port;
+      g_connections[i].fd   = newfd;
+
+      fdstate_open(newfd, g_connections + i, 0);
+
+      /* We expect the connecting side to begin with its tracker_id */
+      io_wantread(newfd);
+    }
+  }
+
+  return;
+}
+
+/* New sync data on the stream */
+static void handle_read(int64_t peersocket) {
+  int         i;
+  int64_t     datalen;
+  uint32_t    tracker_id;
+  proxy_peer *peer = fdstate_cookie(peersocket);
+
+  if (!peer) {
+    /* Can't happen ;) */
+    io_close(peersocket);
+    return;
+  }
+  switch (peer->state & FLAG_MASK) {
+  case FLAG_DISCONNECTED:
+    io_close(peersocket);
+    break; /* Shouldnt happen */
+  case FLAG_CONNECTING:
+  case FLAG_WAITTRACKERID:
+    /* We want at least the first four bytes to come at once, to avoid keeping extra states (for now)
+       This also catches 0 bytes reads == EOF and negative values, denoting connection errors */
+    if (io_tryread(peersocket, (void *)&tracker_id, sizeof(tracker_id)) != sizeof(tracker_id))
+      goto close_socket;
+
+    /* See, if we already have a connection to that peer */
+    for (i = 0; i < MAX_PEERS; ++i)
+      if ((g_connections[i].state & FLAG_MASK) == FLAG_CONNECTED && g_connections[i].tracker_id == tracker_id) {
+        fprintf(stderr, "Peer already connected. Closing connection.\n");
+        goto close_socket;
+      }
+
+    /* Also no need for soliloquy */
+    if (tracker_id == g_tracker_id)
+      goto close_socket;
+
+    /* The new connection is good, send our tracker_id on incoming connections */
+    if (peer->state == FLAG_CONNECTING)
+      if (io_trywrite(peersocket, (void *)&g_tracker_id, sizeof(g_tracker_id)) != sizeof(g_tracker_id))
+        goto close_socket;
+
+    peer->tracker_id = tracker_id;
+    PROXYPEER_SETCONNECTED(peer->state);
+
+    if (peer->state & FLAG_OUTGOING)
+      fprintf(stderr, "succeeded.\n");
+    else
+      fprintf(stderr, "Incoming connection successful.\n");
+
+    break;
+  close_socket:
+    fprintf(stderr, "Handshake incomplete, closing socket\n");
+    io_close(peersocket);
+    reset_info_block(peer);
+    break;
+  case FLAG_CONNECTED:
+    /* Here we acutally expect data from peer
+       indata_length should be less than 20+256*7 bytes, for incomplete torrent entries */
+    datalen = io_tryread(peersocket, (void *)(peer->indata + peer->indata_length), sizeof(peer->indata) - peer->indata_length);
+    if (!datalen || datalen < -1) {
+      fprintf(stderr, "Connection closed by remote peer.\n");
+      io_close(peersocket);
+      reset_info_block(peer);
+    } else if (datalen > 0) {
+      peer->indata_length += datalen;
+      process_indata(peer);
+    }
+    break;
+  }
+}
+
+/* Can write new sync data to the stream */
+static void handle_write(int64_t peersocket) {
+  proxy_peer *peer = fdstate_cookie(peersocket);
+
+  if (!peer) {
+    /* Can't happen ;) */
+    io_close(peersocket);
+    return;
+  }
+
+  switch (peer->state & FLAG_MASK) {
+  case FLAG_DISCONNECTED:
+  default: /* Should not happen */
+    io_close(peersocket);
+    break;
+  case FLAG_CONNECTING:
+    /* Ensure that the connection is established and handle connection error */
+    if (peer->state & FLAG_OUTGOING && !socket_is_connected(peersocket)) {
+      fprintf(stderr, "failed\n");
+      reset_info_block(peer);
+      io_close(peersocket);
+      break;
+    }
+
+    if (io_trywrite(peersocket, (void *)&g_tracker_id, sizeof(g_tracker_id)) == sizeof(g_tracker_id)) {
+      PROXYPEER_SETWAITTRACKERID(peer->state);
+      io_dontwantwrite(peersocket);
+      io_wantread(peersocket);
+    } else {
+      fprintf(stderr, "Handshake incomplete, closing socket\n");
+      io_close(peersocket);
+      reset_info_block(peer);
+    }
+    break;
+  case FLAG_CONNECTED:
+    switch (batch_send(peersocket, &peer->outdata)) {
+    case BATCH_DONE:
+      io_dontwantwrite(peersocket);
+      break;
+    case BATCH_FAILED:
+      io_close(peersocket);
+      reset_info_block(peer);
+      break;
+    default: /* Normal operation or eagain */
+      break;
+    }
+    break;
+  }
+
+  return;
+}
+
+static void server_mainloop() {
+  int64_t  sock;
+  uint32_t packet_type;
+
+  /* inlined livesync_init() */
+  memset(g_peerbuffer_start, 0, sizeof(g_peerbuffer_start));
+  g_peerbuffer_pos = g_peerbuffer_start;
+  memcpy(g_peerbuffer_pos, &g_tracker_id, sizeof(g_tracker_id));
+  packet_type         = htonl(OT_SYNC_PEER);
+  memcpy(g_peerbuffer_pos + sizeof(g_tracker_id), &packet_type, sizeof(packet_type));
+  g_peerbuffer_pos   += sizeof(g_tracker_id) + sizeof(uint32_t);
+  g_next_packet_time  = time(NULL) + LIVESYNC_MAXDELAY;
+
+  while (1) {
+    /* See if we need to connect to anyone */
+    if (time(NULL) > g_connection_reconn)
+      handle_reconnects();
+
+    /* Wait for io events until next approx reconn check time */
+    io_waituntil2(30 * 1000);
+
+    /* Loop over readable sockets */
+    while ((sock = io_canread()) != -1) {
+      const void *cookie = fdstate_cookie(sock);
+      if ((uintptr_t)cookie == FLAG_SERVERSOCKET)
+        handle_accept(sock);
+      else
+        handle_read(sock);
+    }
+
+    /* Loop over writable sockets */
+    while ((sock = io_canwrite()) != -1)
+      handle_write(sock);
+
+    livesync_ticker();
+  }
+}
+
+static void panic(const char *routine) {
+  fprintf(stderr, "%s: %s\n", routine, strerror(errno));
+  exit(111);
+}
+
+static int64_t ot_try_bind(ot_ip6 ip, uint16_t port) {
+  int64_t sock = socket_tcp_listen(ip, port, SOCKET_EXCLUSIVE);
+
+  if (sock == -1)
+    panic("socket_tcp_listen");
+
+  if (!io_fd(sock))
+    panic("io_fd");
+
+  fdstate_open(sock, (void *)FLAG_SERVERSOCKET, 0);
+  io_wantread(sock);
+  return sock;
+}
+
+static int scan_ip6_port(const char *src, ot_ip6 ip, uint16_t *port) {
+  const char *s = src;
+  uint64_t    value;
+  int         off, bracket = 0;
+  while (isspace(*s))
+    ++s;
+  if (*s == '[')
+    ++s, ++bracket; /* for v6 style notation */
+  if (!(off = ip_parse(s, ip)))
+    return 0;
+  s += off;
+  if (*s == 0 || isspace(*s))
+    return s - src;
+  if (*s == ']' && bracket)
+    ++s;
+  if (!ip_is_v4mapped(ip)) {
+    if ((bracket && *(s) != ':') || (*(s) != '.'))
+      return 0;
+    s++;
+  } else {
+    if (*(s++) != ':')
+      return 0;
+  }
+  if (!(off = scan_uint(s, &value, 65535)))
+    return 0;
+  *port = (uint16_t)value;
+  return off + s - src;
+}
+
+int main(int argc, char **argv) {
+  static pthread_t sync_in_thread_id;
+  static pthread_t sync_out_thread_id;
+  ot_ip6           serverip;
+  uint16_t         tmpport;
+  int              scanon = 1, lbound = 0, sbound = 0;
+
+  random_init();
+  if (fdstate_init() == -1)
+    panic("fdstate_init");
+  g_tracker_id = random_uint32();
+
+  while (scanon) {
+    switch (getopt(argc, argv, ":l:c:L:h")) {
+    case -1:
+      scanon = 0;
+      break;
+    case 'l':
+      tmpport = 0;
+      if (!scan_ip6_port(optarg, serverip, &tmpport) || !tmpport) {
+        usage(argv[0]);
+        exit(1);
+      }
+      ot_try_bind(serverip, tmpport);
+      ++sbound;
+      break;
+    case 'c':
+      if (g_connection_count > MAX_PEERS / 2)
+        exerr("Connection limit exceeded.\n");
+      tmpport = 0;
+      if (!scan_ip6_port(optarg, g_connections[g_connection_count].ip, &g_connections[g_connection_count].port) || !g_connections[g_connection_count].port) {
+        usage(argv[0]);
+        exit(1);
+      }
+      g_connections[g_connection_count++].state = FLAG_OUTGOING;
+      break;
+    case 'L':
+      tmpport = 9696;
+      if (!scan_ip6_port(optarg, serverip, &tmpport) || !tmpport) {
+        usage(argv[0]);
+        exit(1);
+      }
+      livesync_bind_mcast(serverip, tmpport);
+      ++lbound;
+      break;
+    default:
+    case '?':
+      usage(argv[0]);
+      exit(1);
+    }
+  }
+
+  if (!lbound)
+    exerr("No livesync port bound.");
+  if (!g_connection_count && !sbound)
+    exerr("No streamsync port bound.");
+  pthread_create(&sync_in_thread_id, NULL, livesync_worker, NULL);
+  pthread_create(&sync_out_thread_id, NULL, streamsync_worker, NULL);
+
+  server_mainloop();
+  return 0;
+}
+
+static void *streamsync_worker(void *args) {
+  (void)args;
+  while (1) {
+    size_t bucket;
+    /* For each bucket... */
+    for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+      /* Get exclusive access to that bucket */
+      ot_vector *torrents_list = mutex_bucket_lock(bucket);
+      size_t     tor_offset, count_def = 0, count_one = 0, count_two = 0, count_peers = 0;
+      size_t     mem, mem_a = 0, mem_b = 0;
+      uint8_t   *ptr = 0, *ptr_a, *ptr_b, *ptr_c;
+
+      if (!torrents_list->size)
+        goto unlock_continue;
+
+      /* For each torrent in this bucket.. */
+      for (tor_offset = 0; tor_offset < torrents_list->size; ++tor_offset) {
+        /* Address torrents members */
+        ot_peerlist *peer_list = (((ot_torrent *)(torrents_list->data))[tor_offset]).peer_list;
+        switch (peer_list->peer_count) {
+        case 2:
+          count_two++;
+          break;
+        case 1:
+          count_one++;
+          break;
+        case 0:
+          break;
+        default:
+          count_def++;
+          count_peers += peer_list->peer_count;
+        }
+      }
+
+      /* Maximal memory requirement: max 3 blocks, max torrents * 20 + max peers * 7 */
+      mem = 3 * (1 + 1 + 2) + (count_one + count_two) * (19 + 1) + count_def * (19 + 8) + (count_one + 2 * count_two + count_peers) * 7;
+
+      fprintf(stderr, "Mem: %zd\n", mem);
+
+      ptr = ptr_a = ptr_b = ptr_c = malloc(mem);
+      if (!ptr)
+        goto unlock_continue;
+
+      if (count_one > 4 || !count_def) {
+        mem_a     = 1 + 1 + 2 + count_one * (19 + 7);
+        ptr_b    += mem_a;
+        ptr_c    += mem_a;
+        ptr_a[0]  = 1;                                     /* Offset 0: packet type 1 */
+        ptr_a[1]  = (bucket << 8) >> OT_BUCKET_COUNT_BITS; /* Offset 1: the shared prefix */
+        ptr_a[2]  = count_one >> 8;
+        ptr_a[3]  = count_one & 255;
+        ptr_a    += 4;
+      } else
+        count_def += count_one;
+
+      if (count_two > 4 || !count_def) {
+        mem_b     = 1 + 1 + 2 + count_two * (19 + 14);
+        ptr_c    += mem_b;
+        ptr_b[0]  = 2;                                     /* Offset 0: packet type 2 */
+        ptr_b[1]  = (bucket << 8) >> OT_BUCKET_COUNT_BITS; /* Offset 1: the shared prefix */
+        ptr_b[2]  = count_two >> 8;
+        ptr_b[3]  = count_two & 255;
+        ptr_b    += 4;
+      } else
+        count_def += count_two;
+
+      if (count_def) {
+        ptr_c[0]  = 0;                                     /* Offset 0: packet type 0 */
+        ptr_c[1]  = (bucket << 8) >> OT_BUCKET_COUNT_BITS; /* Offset 1: the shared prefix */
+        ptr_c[2]  = count_def >> 8;
+        ptr_c[3]  = count_def & 255;
+        ptr_c    += 4;
+      }
+
+      /* For each torrent in this bucket.. */
+      for (tor_offset = 0; tor_offset < torrents_list->size; ++tor_offset) {
+        /* Address torrents members */
+        ot_torrent  *torrent   = ((ot_torrent *)(torrents_list->data)) + tor_offset;
+        ot_peerlist *peer_list = torrent->peer_list;
+        ot_peer     *peers     = (ot_peer *)(peer_list->peers.data);
+        uint8_t    **dst;
+
+        /* Determine destination slot */
+        count_peers = peer_list->peer_count;
+        switch (count_peers) {
+        case 0:
+          continue;
+        case 1:
+          dst = mem_a ? &ptr_a : &ptr_c;
+          break;
+        case 2:
+          dst = mem_b ? &ptr_b : &ptr_c;
+          break;
+        default:
+          dst = &ptr_c;
+          break;
+        }
+
+        /* Copy tail of info_hash, advance pointer */
+        memcpy(*dst, ((uint8_t *)torrent->hash) + 1, sizeof(ot_hash) - 1);
+        *dst += sizeof(ot_hash) - 1;
+
+        /* Encode peer count */
+        if (dst == &ptr_c)
+          while (count_peers) {
+            if (count_peers <= 0x7f)
+              *(*dst)++ = count_peers;
+            else
+              *(*dst)++ = 0x80 | (count_peers & 0x7f);
+            count_peers >>= 7;
+          }
+
+        /* Copy peers */
+        count_peers = peer_list->peer_count;
+        while (count_peers--) {
+          memcpy(*dst, peers++, OT_IP_SIZE + 3);
+          *dst += OT_IP_SIZE + 3;
+        }
+        free_peerlist(peer_list);
+      }
+
+      free(torrents_list->data);
+      memset(torrents_list, 0, sizeof(*torrents_list));
+    unlock_continue:
+      mutex_bucket_unlock(bucket, 0);
+
+      if (ptr) {
+        int i;
+
+        if (ptr_b > ptr_c)
+          ptr_c = ptr_b;
+        if (ptr_a > ptr_c)
+          ptr_c = ptr_a;
+        mem = ptr_c - ptr;
+
+        for (i = 0; i < MAX_PEERS; ++i) {
+          if (PROXYPEER_ISCONNECTED(g_connections[i].state)) {
+            void *tmp = malloc(mem);
+            if (tmp) {
+              memcpy(tmp, ptr, mem);
+              batch_add(&g_connections[i].outdata, tmp, mem);
+              io_wantwrite(g_connections[i].fd);
+            }
+          }
+        }
+
+        free(ptr);
+      }
+      usleep(OT_SYNC_SLEEP);
+    }
+  }
+  return 0;
+}
+
+static void livesync_issue_peersync() {
+  socket_mcast_send(g_socket_out, g_peerbuffer_start, (size_t)(g_peerbuffer_pos - g_peerbuffer_start), groupip_1, LIVESYNC_PORT);
+  g_peerbuffer_pos   = g_peerbuffer_start + sizeof(g_tracker_id) + sizeof(uint32_t);
+  g_next_packet_time = time(NULL) + LIVESYNC_MAXDELAY;
+}
+
+void livesync_ticker() {
+  /* livesync_issue_peersync sets g_next_packet_time */
+  if (time(NULL) > g_next_packet_time && g_peerbuffer_pos > g_peerbuffer_start + sizeof(g_tracker_id))
+    livesync_issue_peersync();
+}
+
+static void livesync_proxytell(uint8_t prefix, uint8_t *info_hash, uint8_t *peer) {
+  //  unsigned int i;
+
+  *g_peerbuffer_pos = prefix;
+  memcpy(g_peerbuffer_pos + 1, info_hash, sizeof(ot_hash) - 1);
+  memcpy(g_peerbuffer_pos + sizeof(ot_hash), peer, sizeof(ot_peer) - 1);
+
+#if 0
+  /* Dump info_hash */
+  for( i=0; i<sizeof(ot_hash); ++i )
+    printf( "%02X", g_peerbuffer_pos[i] );
+  putchar( ':' );
+#endif
+  g_peerbuffer_pos += sizeof(ot_hash);
+#if 0
+  printf( "%hhu.%hhu.%hhu.%hhu:%hu (%02X %02X)\n", g_peerbuffer_pos[0], g_peerbuffer_pos[1], g_peerbuffer_pos[2], g_peerbuffer_pos[3],
+    g_peerbuffer_pos[4] | ( g_peerbuffer_pos[5] << 8 ), g_peerbuffer_pos[6], g_peerbuffer_pos[7] );
+#endif
+  g_peerbuffer_pos += sizeof(ot_peer);
+
+  if (g_peerbuffer_pos >= g_peerbuffer_highwater)
+    livesync_issue_peersync();
+}
+
+static void process_indata(proxy_peer *peer) {
+  size_t   consumed, peers;
+  uint8_t *data    = peer->indata, *hash;
+  uint8_t *dataend = data + peer->indata_length;
+
+  while (1) {
+    /* If we're not inside of a packet, make a new one */
+    if (!peer->packet_tcount) {
+      /* Ensure the header is complete or postpone processing */
+      if (data + 4 > dataend)
+        break;
+      peer->packet_type     = data[0];
+      peer->packet_tprefix  = data[1];
+      peer->packet_tcount   = data[2] * 256 + data[3];
+      data                 += 4;
+      printf("type: %hhu, prefix: %02X, torrentcount: %zd\n", peer->packet_type, peer->packet_tprefix, peer->packet_tcount);
+    }
+
+    /* Ensure size for a minimal torrent block */
+    if (data + sizeof(ot_hash) + OT_IP_SIZE + 3 > dataend)
+      break;
+
+    /* Advance pointer to peer count or peers */
+    hash   = data;
+    data  += sizeof(ot_hash) - 1;
+
+    /* Type 0 has peer count encoded before each peers */
+    peers  = peer->packet_type;
+    if (!peers) {
+      int shift = 0;
+      do
+        peers |= (0x7f & *data) << (7 * shift);
+      while (*(data++) & 0x80 && shift++ < 6);
+    }
+#if 0
+printf( "peers: %zd\n", peers );
+#endif
+    /* Ensure enough data being read to hold all peers */
+    if (data + (OT_IP_SIZE + 3) * peers > dataend) {
+      data = hash;
+      break;
+    }
+    while (peers--) {
+      livesync_proxytell(peer->packet_tprefix, hash, data);
+      data += OT_IP_SIZE + 3;
+    }
+    --peer->packet_tcount;
+  }
+
+  consumed = data - peer->indata;
+  memmove(peer->indata, data, peer->indata_length - consumed);
+  peer->indata_length -= consumed;
+}
+
+static void *livesync_worker(void *args) {
+  (void)args;
+  while (1) {
+    ot_ip6   in_ip;
+    uint16_t in_port;
+    uint32_t packet_type;
+    ssize_t  datalen = socket_recv(g_socket_in, g_inbuffer, LIVESYNC_INCOMING_BUFFSIZE, in_ip, &in_port);
+
+    /* Expect at least tracker id and packet type */
+    if (datalen <= (ssize_t)(sizeof(g_tracker_id) + sizeof(uint32_t)))
+      continue;
+    if (!memcmp(g_inbuffer, &g_tracker_id, sizeof(g_tracker_id))) {
+      /* drop packet coming from ourselves */
+      continue;
+    }
+    memcpy(&packet_type, g_inbuffer + sizeof(g_tracker_id), sizeof(packet_type));
+
+    switch (ntohl(packet_type)) {
+    case OT_SYNC_PEER4:
+      livesync_handle_peersync(datalen, OT_PEER_SIZE4);
+      break;
+    case OT_SYNC_PEER6:
+      livesync_handle_peersync(datalen, OT_PEER_SIZE6);
+      break;
+    default:
+      // fprintf( stderr, "Received an unknown live sync packet type %u.\n", ntohl( packet_type ) );
+      break;
+    }
+  }
+  return 0;
+}
diff --git a/src/trackerlogic.c b/src/trackerlogic.c
new file mode 100644
index 0000000..9565090
--- /dev/null
+++ b/src/trackerlogic.c
@@ -0,0 +1,628 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <arpa/inet.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+/* Opentracker */
+#include "ot_accesslist.h"
+#include "ot_clean.h"
+#include "ot_fmt.h"
+#include "ot_fullscrape.h"
+#include "ot_http.h"
+#include "ot_ip.h"
+#include "ot_livesync.h"
+#include "ot_mutex.h"
+#include "ot_workqueue.h"
+#include "ot_random.h"
+#include "ot_stats.h"
+#include "ot_udp.h"
+#include "ot_vector.h"
+#include "trackerlogic.h"
+
+/* Forward declaration */
+size_t return_peers_for_torrent(struct ot_workstruct *ws, ot_torrent *torrent, size_t amount, char *reply, PROTO_FLAG proto);
+
+void free_peerlist(ot_peerlist *peer_list) {
+  if (peer_list && peer_list->peers.data) {
+    if (OT_PEERLIST_HASBUCKETS(peer_list))
+      vector_clean_list((ot_vector *)peer_list->peers.data, peer_list->peers.size);
+    else
+      free(peer_list->peers.data);
+  }
+  free(peer_list);
+}
+
+void add_torrent_from_saved_state(ot_hash const hash, ot_time base, size_t down_count) {
+  int         exactmatch;
+  ot_torrent *torrent;
+  ot_vector  *torrents_list = mutex_bucket_lock_by_hash(hash);
+
+  if (!accesslist_hashisvalid(hash)) {
+    mutex_bucket_unlock_by_hash(hash, 0);
+    return;
+  }
+
+  torrent = vector_find_or_insert(torrents_list, (void *)hash, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+  if (!torrent || exactmatch) {
+    mutex_bucket_unlock_by_hash(hash, 0);
+    return;
+  }
+
+  /* Create a new torrent entry, then */
+  memset(torrent, 0, sizeof(ot_torrent));
+  memcpy(torrent->hash, hash, sizeof(ot_hash));
+
+  if (!(torrent->peer_list6 = malloc(sizeof(ot_peerlist))) || !(torrent->peer_list4 = malloc(sizeof(ot_peerlist)))) {
+    vector_remove_torrent(torrents_list, torrent);
+    mutex_bucket_unlock_by_hash(hash, 0);
+    return;
+  }
+
+  memset(torrent->peer_list6, 0, sizeof(ot_peerlist));
+  memset(torrent->peer_list4, 0, sizeof(ot_peerlist));
+  torrent->peer_list6->base       = base;
+  torrent->peer_list4->base       = base;
+  torrent->peer_list6->down_count = down_count;
+  torrent->peer_list4->down_count = down_count;
+
+  mutex_bucket_unlock_by_hash(hash, 1);
+}
+
+size_t add_peer_to_torrent_and_return_peers(PROTO_FLAG proto, struct ot_workstruct *ws, size_t amount) {
+  int            exactmatch, delta_torrentcount = 0;
+  ot_torrent    *torrent;
+  ot_peer       *peer_dest;
+  ot_vector     *torrents_list = mutex_bucket_lock_by_hash(*ws->hash);
+  ot_peerlist   *peer_list;
+  size_t         peer_size; /* initialized in next line */
+  ot_peer const *peer_src = peer_from_peer6(&ws->peer, &peer_size);
+
+  if (!accesslist_hashisvalid(*ws->hash)) {
+    mutex_bucket_unlock_by_hash(*ws->hash, 0);
+    if (proto == FLAG_TCP) {
+      const char invalid_hash[] = "d14:failure reason63:Requested download is not authorized for use with this tracker.e";
+      memcpy(ws->reply, invalid_hash, strlen(invalid_hash));
+      return strlen(invalid_hash);
+    }
+    return 0;
+  }
+
+  torrent = vector_find_or_insert(torrents_list, (void *)ws->hash, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+  if (!torrent) {
+    mutex_bucket_unlock_by_hash(*ws->hash, 0);
+    return 0;
+  }
+
+  if (!exactmatch) {
+    /* Create a new torrent entry, then */
+    memset(torrent, 0, sizeof(ot_torrent));
+    memcpy(torrent->hash, *ws->hash, sizeof(ot_hash));
+
+    if (!(torrent->peer_list6 = malloc(sizeof(ot_peerlist))) || !(torrent->peer_list4 = malloc(sizeof(ot_peerlist)))) {
+      vector_remove_torrent(torrents_list, torrent);
+      mutex_bucket_unlock_by_hash(*ws->hash, 0);
+      return 0;
+    }
+
+    memset(torrent->peer_list6, 0, sizeof(ot_peerlist));
+    memset(torrent->peer_list4, 0, sizeof(ot_peerlist));
+    delta_torrentcount = 1;
+  } else
+    clean_single_torrent(torrent);
+
+  torrent->peer_list6->base = time_now_minutes();
+  torrent->peer_list4->base = time_now_minutes();
+
+  peer_list = peer_size == OT_PEER_SIZE6 ? torrent->peer_list6 : torrent->peer_list4;
+
+  /* Check for peer in torrent */
+  peer_dest = vector_find_or_insert_peer(&(peer_list->peers), peer_src, peer_size, &exactmatch);
+  if (!peer_dest) {
+    mutex_bucket_unlock_by_hash(*ws->hash, delta_torrentcount);
+    return 0;
+  }
+
+  /* Tell peer that it's fresh */
+  OT_PEERTIME(ws->peer, OT_PEER_SIZE6) = 0;
+
+  /* Sanitize flags: Whoever claims to have completed download, must be a seeder */
+  if ((OT_PEERFLAG(ws->peer) & (PEER_FLAG_COMPLETED | PEER_FLAG_SEEDING)) == PEER_FLAG_COMPLETED)
+    OT_PEERFLAG(ws->peer) ^= PEER_FLAG_COMPLETED;
+
+  /* If we hadn't had a match create peer there */
+  if (!exactmatch) {
+
+#ifdef WANT_SYNC_LIVE
+    if (proto == FLAG_MCA)
+      OT_PEERFLAG(ws->peer) |= PEER_FLAG_FROM_SYNC;
+    else
+      livesync_tell(ws);
+#endif
+
+    peer_list->peer_count++;
+    if (OT_PEERFLAG(ws->peer) & PEER_FLAG_COMPLETED) {
+      peer_list->down_count++;
+      stats_issue_event(ws, EVENT_COMPLETED, 0, 0);
+    }
+    if (OT_PEERFLAG(ws->peer) & PEER_FLAG_SEEDING)
+      peer_list->seed_count++;
+
+  } else {
+    stats_issue_event(ws, EVENT_RENEW, 0, OT_PEERTIME(peer_dest, peer_size));
+#ifdef WANT_SPOT_WOODPECKER
+    if ((OT_PEERTIME(peer_dest, peer_size) > 0) && (OT_PEERTIME(peer_dest, peer_size) < 20))
+      stats_issue_event(ws, EVENT_WOODPECKER, 0, (uintptr_t)&ws->peer);
+#endif
+#ifdef WANT_SYNC_LIVE
+    /* Won't live sync peers that come back too fast. Only exception:
+       fresh "completed" reports */
+    if (proto != FLAG_MCA) {
+      if (OT_PEERTIME(peer_dest, peer_size) > OT_CLIENT_SYNC_RENEW_BOUNDARY ||
+          (!(OT_PEERFLAG_D(peer_dest, peer_size) & PEER_FLAG_COMPLETED) && (OT_PEERFLAG(ws->peer) & PEER_FLAG_COMPLETED)))
+        livesync_tell(ws);
+    }
+#endif
+
+    if ((OT_PEERFLAG_D(peer_dest, peer_size) & PEER_FLAG_SEEDING) && !(OT_PEERFLAG(ws->peer) & PEER_FLAG_SEEDING))
+      peer_list->seed_count--;
+    if (!(OT_PEERFLAG_D(peer_dest, peer_size) & PEER_FLAG_SEEDING) && (OT_PEERFLAG(ws->peer) & PEER_FLAG_SEEDING))
+      peer_list->seed_count++;
+    if (!(OT_PEERFLAG_D(peer_dest, peer_size) & PEER_FLAG_COMPLETED) && (OT_PEERFLAG(ws->peer) & PEER_FLAG_COMPLETED)) {
+      peer_list->down_count++;
+      stats_issue_event(ws, EVENT_COMPLETED, 0, 0);
+    }
+    if (OT_PEERFLAG_D(peer_dest, peer_size) & PEER_FLAG_COMPLETED)
+      OT_PEERFLAG(ws->peer) |= PEER_FLAG_COMPLETED;
+  }
+
+  memcpy(peer_dest, peer_src, peer_size);
+#ifdef WANT_SYNC
+  if (proto == FLAG_MCA) {
+    mutex_bucket_unlock_by_hash(*ws->hash, delta_torrentcount);
+    return 0;
+  }
+#endif
+
+  ws->reply_size = return_peers_for_torrent(ws, torrent, amount, ws->reply, proto);
+  mutex_bucket_unlock_by_hash(*ws->hash, delta_torrentcount);
+  return ws->reply_size;
+}
+
+static size_t return_peers_all(ot_peerlist *peer_list, size_t peer_size, char *reply) {
+  size_t       bucket, num_buckets = 1;
+  ot_vector   *bucket_list  = &peer_list->peers;
+  size_t       compare_size = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
+  size_t       result       = compare_size * peer_list->peer_count;
+  char        *r_end        = reply + result;
+
+  if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+    num_buckets = bucket_list->size;
+    bucket_list = (ot_vector *)bucket_list->data;
+  }
+
+  for (bucket = 0; bucket < num_buckets; ++bucket) {
+    ot_peer *peers      = bucket_list[bucket].data;
+    size_t   peer_count = bucket_list[bucket].size;
+    while (peer_count--) {
+      if (OT_PEERFLAG_D(peers, peer_size) & PEER_FLAG_SEEDING) {
+        r_end -= compare_size;
+        memcpy(r_end, peers, compare_size);
+      } else {
+        memcpy(reply, peers, compare_size);
+        reply += compare_size;
+      }
+      peers += peer_size;
+    }
+  }
+  return result;
+}
+
+static size_t return_peers_selection(struct ot_workstruct *ws, ot_peerlist *peer_list, size_t peer_size, size_t amount, char *reply) {
+  size_t       bucket_offset, bucket_index = 0, num_buckets = 1;
+  ot_vector   *bucket_list  = &peer_list->peers;
+  unsigned int shifted_pc   = peer_list->peer_count;
+  unsigned int shifted_step = 0;
+  unsigned int shift        = 0;
+  size_t       compare_size = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
+  size_t       result       = compare_size * amount;
+  char        *r_end        = reply + result;
+
+  if (OT_PEERLIST_HASBUCKETS(peer_list)) {
+    num_buckets = bucket_list->size;
+    bucket_list = (ot_vector *)bucket_list->data;
+  }
+
+  /* Make fixpoint arithmetic as exact as possible */
+#define MAXPRECBIT (1 << (8 * sizeof(int) - 3))
+  while (!(shifted_pc & MAXPRECBIT)) {
+    shifted_pc <<= 1;
+    shift++;
+  }
+  shifted_step = shifted_pc / amount;
+#undef MAXPRECBIT
+
+  /* Initialize somewhere in the middle of peers so that
+   fixpoint's aliasing doesn't alway miss the same peers */
+  bucket_offset = nrand48(ws->rand48_state) % peer_list->peer_count;
+
+  while (amount--) {
+    ot_peer *peer;
+
+    /* This is the aliased, non shifted range, next value may fall into */
+    unsigned int diff  = (((amount + 1) * shifted_step) >> shift) - ((amount * shifted_step) >> shift);
+    bucket_offset     += 1 + nrand48(ws->rand48_state) % diff;
+
+    while (bucket_offset >= bucket_list[bucket_index].size) {
+      bucket_offset -= bucket_list[bucket_index].size;
+      bucket_index   = (bucket_index + 1) % num_buckets;
+    }
+    peer = (ot_peer*)bucket_list[bucket_index].data + peer_size * bucket_offset;
+    if (OT_PEERFLAG_D(peer, peer_size) & PEER_FLAG_SEEDING) {
+      r_end -= compare_size;
+      memcpy(r_end, peer, compare_size);
+    } else {
+      memcpy(reply, peer, compare_size);
+      reply += compare_size;
+    }
+  }
+  return result;
+}
+
+static size_t return_peers_for_torrent_udp(struct ot_workstruct *ws, ot_torrent *torrent, size_t amount, char *reply) {
+  char        *r          = reply;
+  size_t       peer_size  = peer_size_from_peer6(&ws->peer);
+  ot_peerlist *peer_list  = peer_size == OT_PEER_SIZE6 ? torrent->peer_list6 : torrent->peer_list4;
+  size_t       peer_count = torrent->peer_list6->peer_count + torrent->peer_list4->peer_count;
+  size_t       seed_count = torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+
+  if (amount > peer_list->peer_count)
+    amount = peer_list->peer_count;
+
+  *(uint32_t *)(r + 0)  = htonl(OT_CLIENT_REQUEST_INTERVAL_RANDOM);
+  *(uint32_t *)(r + 4)  = htonl(peer_count - seed_count);
+  *(uint32_t *)(r + 8)  = htonl(seed_count);
+  r                    += 12;
+
+  if (amount) {
+    if (amount == peer_list->peer_count)
+      r += return_peers_all(peer_list, peer_size, r);
+    else
+      r += return_peers_selection(ws, peer_list, peer_size, amount, r);
+  }
+  return r - reply;
+}
+
+static size_t return_peers_for_torrent_tcp(struct ot_workstruct *ws, ot_torrent *torrent, size_t amount, char *reply) {
+  char       *r          = reply;
+  const char *r_end      = ws->outbuf + G_OUTBUF_SIZE;
+  int         erval      = OT_CLIENT_REQUEST_INTERVAL_RANDOM;
+  size_t      seed_count = torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+  size_t      down_count = torrent->peer_list6->down_count + torrent->peer_list4->down_count;
+  size_t      peer_count = torrent->peer_list6->peer_count + torrent->peer_list4->peer_count - seed_count;
+
+  /* Simple case: amount of peers in both lists is less than requested, here we return all results */
+  size_t amount_v4  = torrent->peer_list4->peer_count;
+  size_t amount_v6  = torrent->peer_list6->peer_count;
+
+  /* Complex case: both lists have more than enough entries and we need to split between v4 and v6 clients */
+  if (amount_v4 + amount_v6 > amount) {
+    size_t       amount_left, percent_v6 = 0, percent_v4 = 0, left_v6, left_v4;
+    const size_t SCALE = 1024;
+
+    /* If possible, fill at least a quarter of peer from each family */
+    if (amount / 4 <= amount_v4)
+      amount_v4 = amount / 4;
+    if (amount / 4 <= amount_v6)
+      amount_v6 = amount / 4;
+
+    /* Fill the rest according to which family's pool provides more peers */
+    amount_left = amount - (amount_v4 + amount_v6);
+
+    left_v4     = torrent->peer_list4->peer_count - amount_v4;
+    left_v6     = torrent->peer_list6->peer_count - amount_v6;
+
+    if (left_v4 + left_v6) {
+      percent_v4 = (SCALE * left_v4) / (left_v4 + left_v6);
+      percent_v6 = (SCALE * left_v6) / (left_v4 + left_v6);
+    }
+
+    amount_v4 += (amount_left * percent_v4) / SCALE;
+    amount_v6 += (amount_left * percent_v6) / SCALE;
+
+    /* Integer division rounding can leave out a peer */
+    if (amount_v4 + amount_v6 < amount && amount_v6 < torrent->peer_list6->peer_count)
+      ++amount_v6;
+    if (amount_v4 + amount_v6 < amount && amount_v4 < torrent->peer_list4->peer_count)
+      ++amount_v4;
+  }
+
+  fmt_append(&r, r_end, "d8:completei%zde10:downloadedi%zde10:incompletei%zde8:intervali%ie12:min intervali%ie", seed_count, down_count, peer_count, erval,
+             erval / 2);
+
+  if (amount_v4) {
+    fmt_append(&r, r_end, PEERS_BENCODED4 "%zd:", OT_PEER_COMPARE_SIZE4 * amount_v4);
+    if (amount_v4 == torrent->peer_list4->peer_count)
+      r += return_peers_all(torrent->peer_list4, OT_PEER_SIZE4, r);
+    else
+      r += return_peers_selection(ws, torrent->peer_list4, OT_PEER_SIZE4, amount_v4, r);
+  }
+
+  if (amount_v6) {
+    fmt_append(&r, r_end, PEERS_BENCODED6 "%zd:", OT_PEER_COMPARE_SIZE6 * amount_v6);
+    if (amount_v6 == torrent->peer_list6->peer_count)
+      r += return_peers_all(torrent->peer_list6, OT_PEER_SIZE6, r);
+    else
+      r += return_peers_selection(ws, torrent->peer_list6, OT_PEER_SIZE6, amount_v6, r);
+  }
+
+  fmt_append(&r, r_end, "e");
+
+  return r - reply;
+}
+
+/* Compiles a list of random peers for a torrent
+ * Reply must have enough space to hold:
+ * 92 + 6 * amount bytes for TCP/IPv4
+ * 92 + 18 * amount bytes for TCP/IPv6
+ * 12 + 6 * amount bytes for UDP/IPv4
+ * 12 + 18 * amount bytes for UDP/IPv6
+ * Does not yet check not to return self
+ */
+size_t return_peers_for_torrent(struct ot_workstruct *ws, ot_torrent *torrent, size_t amount, char *reply, PROTO_FLAG proto) {
+  return proto == FLAG_TCP ? return_peers_for_torrent_tcp(ws, torrent, amount, reply) : return_peers_for_torrent_udp(ws, torrent, amount, reply);
+}
+
+/* Fetches scrape info for a specific torrent */
+size_t return_udp_scrape_for_torrent(ot_hash const hash, char *reply) {
+  int         exactmatch, delta_torrentcount = 0;
+  ot_vector  *torrents_list = mutex_bucket_lock_by_hash(hash);
+  ot_torrent *torrent       = vector_binary_search(hash, torrents_list->data, torrents_list->size, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+
+  if (!exactmatch) {
+    memset(reply, 0, 12);
+  } else {
+    uint32_t *r = (uint32_t *)reply;
+
+    if (clean_single_torrent(torrent)) {
+      vector_remove_torrent(torrents_list, torrent);
+      memset(reply, 0, 12);
+      delta_torrentcount = -1;
+    } else {
+      r[0] = htonl(torrent->peer_list6->seed_count + torrent->peer_list4->seed_count);
+      r[1] = htonl(torrent->peer_list6->down_count + torrent->peer_list4->down_count);
+      r[2] = htonl(torrent->peer_list6->peer_count + torrent->peer_list4->peer_count - torrent->peer_list6->seed_count - torrent->peer_list4->seed_count);
+    }
+  }
+  mutex_bucket_unlock_by_hash(hash, delta_torrentcount);
+  return 12;
+}
+
+/* Fetches scrape info for a specific torrent */
+void return_tcp_scrape_for_torrent(ot_hash const *hash_list, size_t amount, char **reply, const char *reply_end) {
+  int    exactmatch;
+  size_t i;
+
+  fmt_append(reply, reply_end, "d5:filesd");
+
+  for (i = 0; i < amount; ++i) {
+    int            delta_torrentcount = 0;
+    ot_hash const *hash               = hash_list + i;
+    ot_vector     *torrents_list      = mutex_bucket_lock_by_hash(*hash);
+    ot_torrent    *torrent            = vector_binary_search(hash, torrents_list->data, torrents_list->size, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+
+    if (exactmatch) {
+      if (clean_single_torrent(torrent)) {
+        vector_remove_torrent(torrents_list, torrent);
+        delta_torrentcount = -1;
+      } else {
+        fmt_append(reply, reply_end, "20:");
+        fmt_bytes(reply, reply_end, hash, sizeof(ot_hash));
+        fmt_append(reply, reply_end, "d8:completei%zde10:downloadedi%zde10:incompletei%zdee",
+                   torrent->peer_list6->seed_count + torrent->peer_list4->seed_count, torrent->peer_list6->down_count + torrent->peer_list4->down_count,
+                   torrent->peer_list6->peer_count + torrent->peer_list4->peer_count - torrent->peer_list6->seed_count - torrent->peer_list4->seed_count);
+      }
+    }
+    mutex_bucket_unlock_by_hash(*hash, delta_torrentcount);
+  }
+
+  fmt_append(reply, reply_end, "ee");
+}
+
+static ot_peerlist dummy_list;
+size_t remove_peer_from_torrent(PROTO_FLAG proto, struct ot_workstruct *ws) {
+  int            exactmatch;
+  ot_vector     *torrents_list = mutex_bucket_lock_by_hash(*ws->hash);
+  ot_torrent    *torrent = vector_binary_search(ws->hash, torrents_list->data, torrents_list->size, sizeof(ot_torrent), OT_HASH_COMPARE_SIZE, &exactmatch);
+  ot_peerlist   *peer_list = &dummy_list;
+  size_t         peer_size; /* initialized in next line */
+  ot_peer const *peer_src   = peer_from_peer6(&ws->peer, &peer_size);
+  size_t         peer_count = 0, seed_count = 0;
+
+#ifdef WANT_SYNC_LIVE
+  if (proto != FLAG_MCA) {
+    OT_PEERFLAG(ws->peer) |= PEER_FLAG_STOPPED;
+    livesync_tell(ws);
+  }
+#endif
+
+  if (exactmatch) {
+    peer_list = peer_size == OT_PEER_SIZE6 ? torrent->peer_list6 : torrent->peer_list4;
+    switch (vector_remove_peer(&peer_list->peers, peer_src, peer_size)) {
+    case 2:
+      peer_list->seed_count--; /* Intentional fallthrough */
+    case 1:
+      peer_list->peer_count--; /* Intentional fallthrough */
+    default:
+      break;
+    }
+
+    peer_count = torrent->peer_list6->peer_count + torrent->peer_list4->peer_count;
+    seed_count = torrent->peer_list6->seed_count + torrent->peer_list4->seed_count;
+  }
+
+  if (proto == FLAG_TCP) {
+    int   erval = OT_CLIENT_REQUEST_INTERVAL_RANDOM;
+    char *r     = ws->reply;
+
+    fmt_append(&r, ws->outbuf + G_OUTBUF_SIZE, "d8:completei%zde10:incompletei%zde8:intervali%ie12:min intervali%ie%s0:e", seed_count, peer_count - seed_count,
+               erval, erval / 2, peer_size == OT_PEER_SIZE6 ? PEERS_BENCODED6 : PEERS_BENCODED4);
+    ws->reply_size = r - ws->reply;
+  }
+
+  /* Handle UDP reply */
+  if (proto == FLAG_UDP) {
+    ((uint32_t *)ws->reply)[2] = htonl(OT_CLIENT_REQUEST_INTERVAL_RANDOM);
+    ((uint32_t *)ws->reply)[3] = htonl(peer_count - seed_count);
+    ((uint32_t *)ws->reply)[4] = htonl(seed_count);
+    ws->reply_size             = 20;
+  }
+
+  mutex_bucket_unlock_by_hash(*ws->hash, 0);
+  return ws->reply_size;
+}
+
+void iterate_all_torrents(int (*for_each)(ot_torrent *torrent, uintptr_t data), uintptr_t data) {
+  size_t bucket, j;
+
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    ot_vector  *torrents_list = mutex_bucket_lock(bucket);
+    ot_torrent *torrents      = (ot_torrent *)(torrents_list->data);
+
+    for (j = 0; j < torrents_list->size; ++j)
+      if (for_each(torrents + j, data))
+        break;
+
+    mutex_bucket_unlock(bucket, 0);
+    if (!g_opentracker_running)
+      return;
+  }
+}
+
+ot_peer *peer_from_peer6(ot_peer6 *peer, size_t *peer_size) {
+  ot_ip6 *ip = (ot_ip6 *)peer;
+  if (!ip_is_v4mapped(ip)) {
+    *peer_size = OT_PEER_SIZE6;
+    return (ot_peer *)peer;
+  }
+  *peer_size = OT_PEER_SIZE4;
+  return (ot_peer *)(((uint8_t *)peer) + 12);
+}
+
+size_t peer_size_from_peer6(ot_peer6 *peer) {
+  ot_ip6 *ip = (ot_ip6 *)peer;
+  if (!ip_is_v4mapped(ip))
+    return OT_PEER_SIZE6;
+  return OT_PEER_SIZE4;
+}
+
+#ifdef _DEBUG_RANDOMTORRENTS
+void trackerlogic_add_random_torrents(size_t amount) {
+  struct ot_workstruct ws;
+  memset(&ws, 0, sizeof(ws));
+
+  ws.inbuf  = malloc(G_INBUF_SIZE);
+  ws.outbuf = malloc(G_OUTBUF_SIZE);
+  ws.reply  = ws.outbuf;
+  ws.hash   = (ot_hash *)ws.inbuf;
+
+  while (amount--) {
+    random_bytes(ws.hash, sizeof(ot_hash));
+    random_bytes(&ws.peer, sizeof(ws.peer));
+
+    OT_PEERFLAG(ws.peer) &= PEER_FLAG_SEEDING | PEER_FLAG_COMPLETED | PEER_FLAG_STOPPED;
+
+    add_peer_to_torrent_and_return_peers(FLAG_TCP, &ws, 1);
+  }
+
+  free(ws.inbuf);
+  free(ws.outbuf);
+}
+#endif
+
+void exerr(const char *message) {
+  fprintf(stderr, "%s\n", message);
+  exit(111);
+}
+
+void trackerlogic_init(void) {
+  g_tracker_id = random_uint32();
+
+  if (!g_stats_path)
+    g_stats_path = "stats";
+  g_stats_path_len = strlen(g_stats_path);
+
+  /* Initialise background worker threads */
+  mutex_init();
+  workqueue_init();
+  clean_init();
+  fullscrape_init();
+  accesslist_init();
+  livesync_init();
+  stats_init();
+}
+
+int workstruct_init(struct ot_workstruct *ws) {
+  memset(ws, 0, sizeof(*ws));
+  ws->inbuf  = malloc(G_INBUF_SIZE);
+  ws->outbuf = malloc(G_OUTBUF_SIZE);
+#ifdef _DEBUG_HTTPERROR
+  ws->debugbuf = malloc(G_DEBUGBUF_SIZE);
+#endif
+  if (!ws->inbuf || !ws->outbuf)
+    return -1;
+
+  /* Picking which peers to hand out starts here, so two workers seeded alike
+     would hand out alike */
+  random_bytes(ws->rand48_state, sizeof(ws->rand48_state));
+
+  stats_counters_register(ws);
+  return 0;
+}
+
+void workstruct_deinit(struct ot_workstruct *ws) {
+  /* The tally goes to the global before this struct goes out of scope */
+  stats_counters_retire(ws);
+
+  free(ws->inbuf);
+  free(ws->outbuf);
+#ifdef _DEBUG_HTTPERROR
+  free(ws->debugbuf);
+#endif
+}
+
+void trackerlogic_deinit(void) {
+  int    delta_torrentcount = 0;
+  size_t bucket, j;
+
+  /* Stop the background workers first */
+  stats_deinit();
+  livesync_deinit();
+  accesslist_deinit();
+  fullscrape_deinit();
+  clean_deinit();
+
+  /* Free all torrents... */
+  for (bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket) {
+    ot_vector *torrents_list = mutex_bucket_lock(bucket);
+    if (torrents_list->size) {
+      for (j = 0; j < torrents_list->size; ++j) {
+        ot_torrent *torrent = ((ot_torrent *)(torrents_list->data)) + j;
+        free_peerlist(torrent->peer_list6);
+        free_peerlist(torrent->peer_list4);
+        delta_torrentcount -= 1;
+      }
+      free(torrents_list->data);
+    }
+    mutex_bucket_unlock(bucket, delta_torrentcount);
+  }
+
+  /* Release mutexes */
+  workqueue_deinit();
+  mutex_deinit();
+}
diff --git a/src/trackerlogic.h b/src/trackerlogic.h
new file mode 100644
index 0000000..7292d36
--- /dev/null
+++ b/src/trackerlogic.h
@@ -0,0 +1,283 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+#ifndef OT_TRACKERLOGIC_H__
+#define OT_TRACKERLOGIC_H__
+
+#include <signal.h>
+#include <stdatomic.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <time.h>
+
+typedef uint8_t ot_hash[20];
+typedef time_t  ot_time;
+typedef char    ot_ip6[16];
+typedef struct {
+  ot_ip6 address;
+  int    bits;
+} ot_net;
+/* List of peers should fit in a single UDP packet (around 1200 bytes) */
+#define OT_MAX_PEERS_UDP6               66
+#define OT_MAX_PEERS_UDP4               200
+
+#define OT_IP_SIZE6                     16
+#define OT_IP_SIZE4                     4
+#define OT_PORT_SIZE                    2
+#define OT_FLAG_SIZE                    1
+#define OT_TIME_SIZE                    1
+
+/* Some tracker behaviour tunable */
+#ifndef OT_CLIENT_TIMEOUT
+#define OT_CLIENT_TIMEOUT               30
+#endif
+#ifndef OT_CLIENT_TIMEOUT_CHECKINTERVAL
+#define OT_CLIENT_TIMEOUT_CHECKINTERVAL 10
+#endif
+#define OT_CLIENT_TIMEOUT_SEND          (60 * 15)
+#define OT_CLIENT_REQUEST_INTERVAL      (60 * 30)
+#define OT_CLIENT_REQUEST_VARIATION     (60 * 6)
+
+#define OT_TORRENT_TIMEOUT_HOURS        24
+#define OT_TORRENT_TIMEOUT              (60 * OT_TORRENT_TIMEOUT_HOURS)
+
+#define OT_CLIENT_REQUEST_INTERVAL_RANDOM                                                                                                                      \
+  (OT_CLIENT_REQUEST_INTERVAL - OT_CLIENT_REQUEST_VARIATION / 2 + (int)(nrand48(ws->rand48_state) % OT_CLIENT_REQUEST_VARIATION))
+
+/* If WANT_MODEST_FULLSCRAPES is on, ip addresses may not
+   fullscrape more frequently than this amount in seconds */
+#define OT_MODEST_PEER_TIMEOUT        (60 * 5)
+
+/* If peers come back before 10 minutes, don't live sync them */
+#define OT_CLIENT_SYNC_RENEW_BOUNDARY 10
+
+/* Number of tracker admin ip addresses allowed */
+#define OT_ADMINIP_MAX                64
+#define OT_MAX_THREADS                64
+
+/* Number of minutes after announce before peer is removed */
+#define OT_PEER_TIMEOUT               45
+
+/* We maintain a list of 1024 pointers to sorted list of ot_torrent structs
+ Sort key is, of course, its hash */
+/* Set from the Makefile, 8 to 16. More buckets means shorter vectors and a
+   cheaper insert, which only pays for a tracker carrying millions of
+   torrents; see DESIGN. */
+#ifndef OT_BUCKET_COUNT_BITS
+#define OT_BUCKET_COUNT_BITS          10
+#endif
+
+#define OT_BUCKET_COUNT               (1 << OT_BUCKET_COUNT_BITS)
+#define OT_BUCKET_COUNT_SHIFT         (32 - OT_BUCKET_COUNT_BITS)
+
+/* if _DEBUG_RANDOMTORRENTS is set, this is the amount of torrents to create
+   on startup */
+#define RANDOMTORRENTS                (1024 * 1024 * 1)
+
+#if defined(CLOCK_REALTIME_COARSE)
+#define OT_CLOCK_CHEAP CLOCK_REALTIME_COARSE /* Linux */
+#elif defined(CLOCK_REALTIME_FAST)
+#define OT_CLOCK_CHEAP CLOCK_REALTIME_FAST /* the BSDs */
+#else
+#define OT_CLOCK_CHEAP CLOCK_REALTIME /* macOS and whatever else */
+#endif
+
+static inline ot_time time_now_seconds(void) {
+  struct timespec now;
+  clock_gettime(OT_CLOCK_CHEAP, &now);
+  return (ot_time)now.tv_sec;
+}
+
+static inline ot_time time_now_minutes(void) { return time_now_seconds() / 60; }
+
+/* For the deadlines the tracker sets on itself, which read better as the
+   span they allow than as an addition to the current second */
+static inline ot_time time_future_seconds(int span) { return time_now_seconds() + span; }
+/* Cleared from the interrupt handler and read by every worker */
+extern _Atomic int    g_opentracker_running;
+
+/* Sent to a thread parked in a blocking read */
+#define OT_SIGNAL_WAKE SIGUSR1
+
+
+extern uint32_t g_tracker_id;
+typedef enum { FLAG_TCP, FLAG_UDP, FLAG_MCA, FLAG_SELFPIPE } PROTO_FLAG;
+
+#define OT_PEER_COMPARE_SIZE6                          ((OT_IP_SIZE6) + (OT_PORT_SIZE))
+#define OT_PEER_COMPARE_SIZE4                          ((OT_IP_SIZE4) + (OT_PORT_SIZE))
+#define OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(PEER_SIZE) ((PEER_SIZE) - (OT_TIME_SIZE) - (OT_FLAG_SIZE))
+
+#define OT_PEER_SIZE6                                  ((OT_TIME_SIZE) + (OT_FLAG_SIZE) + (OT_PEER_COMPARE_SIZE6))
+#define OT_PEER_SIZE4                                  ((OT_TIME_SIZE) + (OT_FLAG_SIZE) + (OT_PEER_COMPARE_SIZE4))
+
+typedef uint8_t      ot_peer; /* Generic pointer to a v6 or v4 peer */
+typedef uint8_t      ot_peer6[OT_PEER_SIZE6];
+typedef uint8_t      ot_peer4[OT_PEER_SIZE4];
+static const uint8_t PEER_FLAG_SEEDING   = 0x80;
+static const uint8_t PEER_FLAG_COMPLETED = 0x40;
+static const uint8_t PEER_FLAG_STOPPED   = 0x20;
+static const uint8_t PEER_FLAG_FROM_SYNC = 0x10;
+static const uint8_t PEER_FLAG_LEECHING  = 0x00;
+
+/* Takes an ot_peer6 and returns the proper pointer to the peer and sets peer_size */
+ot_peer             *peer_from_peer6(ot_peer6 *peer, size_t *peer_size);
+size_t               peer_size_from_peer6(ot_peer6 *peer);
+
+/* New style */
+#define OT_SETIP(peer, ip)            memcpy((uint8_t *)(peer), (ip), OT_IP_SIZE6)
+#define OT_SETPORT(peer, port)        memcpy(((uint8_t *)(peer)) + (OT_IP_SIZE6), (port), 2)
+#define OT_PEERFLAG(peer)             (((uint8_t *)(peer))[(OT_IP_SIZE6) + 2])
+#define OT_PEERFLAG_D(peer, peersize) (((uint8_t *)(peer))[(peersize) - 2])
+#define OT_PEERTIME(peer, peersize)   (((uint8_t *)(peer))[(peersize) - 1])
+
+#define PEERS_BENCODED6               "6:peers6"
+#define PEERS_BENCODED4               "5:peers"
+
+#define OT_HASH_COMPARE_SIZE          (sizeof(ot_hash))
+
+struct ot_peerlist;
+typedef struct ot_peerlist ot_peerlist;
+typedef struct {
+  ot_hash      hash;
+  ot_peerlist *peer_list6;
+  ot_peerlist *peer_list4;
+} ot_torrent;
+
+#include "ot_vector.h"
+
+struct ot_peerlist {
+  ot_time   base;
+  size_t    seed_count;
+  size_t    peer_count;
+  size_t    down_count;
+  /* normal peers vector or
+     pointer to ot_vector[32] buckets if data != NULL and space == 0
+  */
+  ot_vector peers;
+};
+#define OT_PEERLIST_HASBUCKETS(peer_list) ((peer_list)->peers.size > (peer_list)->peers.space)
+
+/* The http replies the tracker counts when it has to refuse a request. */
+enum {
+  CODE_HTTPERROR_302,
+  CODE_HTTPERROR_400,
+  CODE_HTTPERROR_400_PARAM,
+  CODE_HTTPERROR_400_COMPACT,
+  CODE_HTTPERROR_402_NOTMODEST,
+  CODE_HTTPERROR_402_PAYMENT_REQUIRED,
+  CODE_HTTPERROR_403_IP,
+  CODE_HTTPERROR_404,
+  CODE_HTTPERROR_500,
+
+  CODE_HTTPERROR_COUNT
+};
+
+/* One statistic. Used when workers report stats to their workstruct */
+typedef _Atomic unsigned long long ot_counter;
+
+/* What each thread counts for itself. The two runs at the end are indexed by
+   the http error code and by the age in minutes of a renewed peer */
+typedef enum {
+  OT_COUNTER_TCP_CONNECTIONS,
+  OT_COUNTER_UDP_CONNECTIONS,
+  OT_COUNTER_TCP_ANNOUNCES,
+  OT_COUNTER_UDP_ANNOUNCES,
+  OT_COUNTER_TCP_SCRAPES,
+  OT_COUNTER_UDP_SCRAPES,
+  OT_COUNTER_TCP_CONNECTS,
+  OT_COUNTER_UDP_CONNECTS,
+  OT_COUNTER_UDP_CONNID_MISSMATCH,
+  OT_COUNTER_COMPLETED,
+  OT_COUNTER_FULLSCRAPES,
+  OT_COUNTER_FULLSCRAPE_REQUESTS,
+  OT_COUNTER_FULLSCRAPE_BYTES,
+  OT_COUNTER_SYNCS,
+  OT_COUNTER_STALLS,
+
+  OT_COUNTER_FAILED,                                             /* CODE_HTTPERROR_COUNT of them */
+  OT_COUNTER_RENEWED = OT_COUNTER_FAILED + CODE_HTTPERROR_COUNT, /* OT_PEER_TIMEOUT of them */
+
+  OT_COUNTER_COUNT   = OT_COUNTER_RENEWED + OT_PEER_TIMEOUT
+} ot_counter_index;
+
+struct ot_workstruct {
+  /* Thread specific, static */
+
+  /* This thread's own statistics, and the link ot_stats keeps them on */
+  ot_counter            counters[OT_COUNTER_COUNT];
+  struct ot_workstruct *counters_next;
+
+  char *inbuf;
+#define G_INBUF_SIZE 8192
+  char *outbuf;
+#define G_OUTBUF_SIZE 8192
+#ifdef _DEBUG_HTTPERROR
+  char *debugbuf;
+#define G_DEBUGBUF_SIZE 8192
+#endif
+
+  /* The peer currently in the working */
+  ot_peer6 peer; /* Can fit v6 and v4 peers */
+
+  /* Pointers into the request buffer */
+  ot_hash *hash;
+  char    *peer_id;
+
+  /* HTTP specific, non static */
+  char    *request;
+  ssize_t  request_size;
+  ssize_t  header_size;
+  char    *reply;
+  ssize_t  reply_size;
+
+  /* Entropy state for rand48 function so that threads don't need to acquire mutexes for
+     global random() or arc4random() state, which causes heavy load on linuxes */
+  uint16_t rand48_state[3];
+
+  int      keep_alive;
+};
+
+/* Everything a thread that serves requests needs for itself. Set up and torn
+   down in one place so that a new kind of worker cannot miss a piece.
+   Returns -1 if the buffers could not be had. */
+int  workstruct_init(struct ot_workstruct *ws);
+void workstruct_deinit(struct ot_workstruct *ws);
+
+/*
+   Exported functions
+*/
+
+#ifdef WANT_SYNC_LIVE
+#define WANT_SYNC
+#endif
+
+#ifdef WANT_SYNC
+#define WANT_SYNC_PARAM(param) , param
+#else
+#define WANT_SYNC_PARAM(param)
+#endif
+
+void   trackerlogic_init(void);
+void   trackerlogic_deinit(void);
+void   exerr(const char *message);
+
+/* add_peer_to_torrent does only release the torrent bucket if from_sync is set,
+   otherwise it is released in return_peers_for_torrent */
+size_t add_peer_to_torrent_and_return_peers(PROTO_FLAG proto, struct ot_workstruct *ws, size_t amount);
+size_t remove_peer_from_torrent(PROTO_FLAG proto, struct ot_workstruct *ws);
+void   return_tcp_scrape_for_torrent(ot_hash const *hash_list, size_t amount, char **reply, const char *reply_end);
+size_t return_udp_scrape_for_torrent(ot_hash const hash, char *reply);
+void   add_torrent_from_saved_state(ot_hash const hash, ot_time base, size_t down_count);
+#ifdef _DEBUG_RANDOMTORRENTS
+void trackerlogic_add_random_torrents(size_t amount);
+#endif
+
+/* torrent iterator */
+void iterate_all_torrents(int (*for_each)(ot_torrent *torrent, uintptr_t data), uintptr_t data);
+
+/* Helper, before it moves to its own object */
+void free_peerlist(ot_peerlist *peer_list);
+
+#endif