3 files changed, 84 insertions, 24 deletions

diff --git a/ot_http.c b/ot_http.c
index 374d6d8..53de0e8 100644
--- a/ot_http.c
+++ b/ot_http.c
@@ -588,7 +588,7 @@ ssize_t http_handle_request( const int64 sock, struct ot_workstruct *ws ) {
   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;
 
diff --git a/trackerlogic.c b/trackerlogic.c
index a0bbeb4..b52b478 100644
--- a/trackerlogic.c
+++ b/trackerlogic.c
@@ -276,32 +276,18 @@ static size_t return_peers_selection( struct ot_workstruct *ws, ot_peerlist *pee
   return result;
 }
 
-/* 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 ) {
+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;
-  char        *r = reply;
-  size_t      compare_size = OT_PEER_COMPARE_SIZE_FROM_PEER_SIZE(peer_size);
 
   if( amount > peer_list->peer_count )
     amount = peer_list->peer_count;
 
-  if( proto == FLAG_TCP ) {
-    int erval = OT_CLIENT_REQUEST_INTERVAL_RANDOM;
-    r += sprintf( r, "d8:completei%zde10:downloadedi%zde10:incompletei%zde8:intervali%ie12:min intervali%ie%s%zd:", peer_list->seed_count, peer_list->down_count, peer_list->peer_count-peer_list->seed_count, erval, erval/2, peer_size == OT_PEER_SIZE6 ? PEERS_BENCODED6 : PEERS_BENCODED4, compare_size * amount );
-  } else {
-    *(uint32_t*)(r+0) = htonl( OT_CLIENT_REQUEST_INTERVAL_RANDOM );
-    *(uint32_t*)(r+4) = htonl( peer_list->peer_count - peer_list->seed_count );
-    *(uint32_t*)(r+8) = htonl( peer_list->seed_count );
-    r += 12;
-  }
+  *(uint32_t*)(r+0) = htonl( OT_CLIENT_REQUEST_INTERVAL_RANDOM );
+  *(uint32_t*)(r+4) = htonl( peer_list->peer_count - peer_list->seed_count );
+  *(uint32_t*)(r+8) = htonl( peer_list->seed_count );
+  r += 12;
 
   if( amount ) {
     if( amount == peer_list->peer_count )
@@ -309,13 +295,87 @@ size_t return_peers_for_torrent( struct ot_workstruct * ws, ot_torrent *torrent,
     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;
+  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;
+  }
+
+  r += sprintf( r, "d8:completei%zde10:downloadedi%zde10:incompletei%zde8:intervali%ie12:min intervali%ie", seed_count, down_count, peer_count, erval, erval/2 );
+
+  if( amount_v4 ) {
+    r += sprintf( r, 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( proto == FLAG_TCP )
-    *r++ = 'e';
+  if( amount_v6 ) {
+    r += sprintf( r, 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 );
+  }
+
+  *r++ = '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;
diff --git a/trackerlogic.h b/trackerlogic.h
index 4fb8bc7..9f5886d 100644
--- a/trackerlogic.h
+++ b/trackerlogic.h
@@ -82,7 +82,7 @@ typedef enum { FLAG_TCP, FLAG_UDP, FLAG_MCA, FLAG_SELFPIPE } PROTO_FLAG;
 #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[1]; /* Generic pointer to a v6 or v4 peer */
+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;