An open and free bittorrent tracker https://erdgeist.org/gitweb/opentracker
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/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
It is considered beerware. Prost. Skol. Cheers or whatever. */
/* System */
#include <string.h>
#include <arpa/inet.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;
}
}