1 files changed, 156 insertions, 0 deletions

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);
+}