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.
$id$ */
/* System */
#include <string.h>
#include <arpa/inet.h>
#include <stdio.h>
/* Libowfat */
#include "socket.h"
#include "io.h"
/* Opentracker */
#include "trackerlogic.h"
#include "ot_udp.h"
#include "ot_stats.h"
static char static_inbuf[8192];
static char static_outbuf[8192];
static const uint8_t g_static_connid[8] = { 0x23, 0x42, 0x05, 0x17, 0xde, 0x41, 0x50, 0xff };
static void udp_make_connectionid( uint32_t * connid, const char * remoteip ) {
/* Touch unused variable */
(void)remoteip;
/* Use a static secret for now */
memcpy( connid, g_static_connid, 8 );
}
static int udp_test_connectionid( const uint32_t * const connid, const char * remoteip ) {
/* Touch unused variable */
(void)remoteip;
/* Test against our static secret */
return !memcmp( connid, g_static_connid, 8 );
}
/* 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];
uint32_t *inpacket = (uint32_t*)static_inbuf;
uint32_t *outpacket = (uint32_t*)static_outbuf;
uint32_t numwant, left, event;
uint16_t port, remoteport;
size_t r, r_out;
r = socket_recv4( serversocket, static_inbuf, sizeof( static_inbuf ), remoteip, &remoteport);
stats_issue_event( EVENT_ACCEPT, FLAG_UDP, ntohl(*(uint32_t*)remoteip) );
stats_issue_event( EVENT_READ, FLAG_UDP, r );
/* Minimum udp tracker packet size, also catches error */
if( r < 16 )
return;
/* fprintf( stderr, "UDP Connection id: %16llX\n", *(uint64_t*)inpacket ); */
switch( ntohl( inpacket[2] ) ) {
case 0: /* This is a connect action */
/* look for udp bittorrent magic id */
if( (ntohl(inpacket[0]) != 0x00000417) || (ntohl(inpacket[1]) != 0x27101980) )
return;
outpacket[0] = 0;
outpacket[1] = inpacket[3];
udp_make_connectionid( outpacket + 2, remoteip );
socket_send4( serversocket, static_outbuf, 16, remoteip, remoteport );
stats_issue_event( EVENT_CONNECT, FLAG_UDP, 16 );
break;
case 1: /* This is an announce action */
/* Minimum udp announce packet size */
if( r < 98 )
return;
if( !udp_test_connectionid( inpacket, remoteip ))
fprintf( stderr, "UDP connect Connection id missmatch.\n" );
/* We do only want to know, if it is zero */
left = inpacket[64/4] | inpacket[68/4];
numwant = ntohl( inpacket[92/4] );
if (numwant > 200) numwant = 200;
event = ntohl( inpacket[80/4] );
port = *(uint16_t*)( 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, FLAG_UDP );
else {
torrent = add_peer_to_torrent( hash, &peer WANT_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, FLAG_UDP, r );
break;
case 2: /* This is a scrape action */
if( !udp_test_connectionid( inpacket, remoteip ))
fprintf( stderr, "UDP scrape Connection id missmatch.\n" );
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, FLAG_UDP, r );
break;
}
}
const char *g_version_udp_c = "$Source: /home/cvsroot/opentracker/ot_udp.c,v $: $Revision: 1.14 $\n";