1 files changed, 102 insertions, 0 deletions

diff --git a/ot_udp.c b/ot_udp.c
new file mode 100644
index 0000000..94d7d3c
--- /dev/null
+++ b/ot_udp.c
@@ -0,0 +1,102 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <string.h>
+
+/* Libowfat */
+#include "socket.h"
+#include "io.h"
+
+/* Opentracker */
+#include "trackerlogic.h"
+#include "ot_udp.h"
+#include "ot_stats.h"
+
+/* UDP implementation according to http://xbtt.sourceforge.net/udp_tracker_protocol.html */
+void handle_udp4( int64 serversocket ) {
+  ot_peer     peer;
+  ot_torrent *torrent;
+  ot_hash    *hash = NULL;
+  char        remoteip[4];
+  ot_dword   *inpacket = (ot_dword*)static_inbuf;
+  ot_dword   *outpacket = (ot_dword*)static_outbuf;
+  ot_dword    numwant, left, event;
+  ot_word     port, remoteport;
+  size_t      r, r_out;
+
+  r = socket_recv4( serversocket, static_inbuf, sizeof( static_inbuf ), remoteip, &remoteport);
+
+  stats_issue_event( EVENT_ACCEPT, 0, 0 );
+  stats_issue_event( EVENT_READ, 0, r );
+
+  /* Minimum udp tracker packet size, also catches error */
+  if( r < 16 )
+    return;
+
+  /* look for udp bittorrent magic id */
+  if( (ntohl(inpacket[0]) != 0x00000417) || (ntohl(inpacket[1]) != 0x27101980) )
+    return;
+
+  switch( ntohl( inpacket[2] ) ) {
+    case 0: /* This is a connect action */
+      outpacket[0] = 0;           outpacket[1] = inpacket[3];
+      outpacket[2] = inpacket[0]; outpacket[3] = inpacket[1];
+      socket_send4( serversocket, static_outbuf, 16, remoteip, remoteport );
+      stats_issue_event( EVENT_CONNECT, 0, 16 );
+      break;
+    case 1: /* This is an announce action */
+      /* Minimum udp announce packet size */
+      if( r < 98 )
+        return;
+
+      numwant = 200;
+      /* We do only want to know, if it is zero */
+      left  = inpacket[64/4] | inpacket[68/4];
+
+      event = ntohl( inpacket[80/4] );
+      port  = *(ot_word*)( static_inbuf + 96 );
+      hash  = (ot_hash*)( static_inbuf + 16 );
+
+      OT_SETIP( &peer, remoteip );
+      OT_SETPORT( &peer, &port );
+      OT_FLAG( &peer ) = 0;
+
+      switch( event ) {
+        case 1: OT_FLAG( &peer ) |= PEER_FLAG_COMPLETED; break;
+        case 3: OT_FLAG( &peer ) |= PEER_FLAG_STOPPED; break;
+        default: break;
+      }
+
+      if( !left )
+        OT_FLAG( &peer )         |= PEER_FLAG_SEEDING;
+
+      outpacket[0] = htonl( 1 );    /* announce action */
+      outpacket[1] = inpacket[12/4];
+
+      if( OT_FLAG( &peer ) & PEER_FLAG_STOPPED ) /* Peer is gone. */
+        r = remove_peer_from_torrent( hash, &peer, static_outbuf, 0 );
+      else {
+        torrent = add_peer_to_torrent( hash, &peer  WANT_TRACKER_SYNC_PARAM( 0 ) );
+        if( !torrent )
+          return; /* XXX maybe send error */
+
+        r = 8 + return_peers_for_torrent( hash, numwant, static_outbuf + 8, 0 );
+      }
+
+      socket_send4( serversocket, static_outbuf, r, remoteip, remoteport );
+      stats_issue_event( EVENT_ANNOUNCE, 0, r );
+      break;
+
+    case 2: /* This is a scrape action */
+      outpacket[0] = htonl( 2 );    /* scrape action */
+      outpacket[1] = inpacket[12/4];
+
+      for( r_out = 0; ( r_out * 20 < r - 16) && ( r_out <= 74 ); r_out++ )
+        return_udp_scrape_for_torrent( (ot_hash*)( static_inbuf + 16 + 20 * r_out ), static_outbuf + 8 + 12 * r_out );
+
+      socket_send4( serversocket, static_outbuf, 8 + 12 * r_out, remoteip, remoteport );
+      stats_issue_event( EVENT_SCRAPE, 0, r );
+      break;
+  }
+}