summaryrefslogtreecommitdiff
path: root/ot_udp.c
blob: 81c4d632895a51c730d8dc976805df41f40d3a47 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
/* 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 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 */
  memmove( 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, struct ot_workstruct *ws ) {
  ot_peer     peer;
  ot_hash    *hash = NULL;
  char        remoteip[4];
  uint32_t   *inpacket = (uint32_t*)ws->inbuf;
  uint32_t   *outpacket = (uint32_t*)ws->outbuf;
  uint32_t    numwant, left, event;
  uint16_t    port, remoteport;
  size_t      r, r_out;

  r = socket_recv4( serversocket, ws->inbuf, ws->inbuf_size, 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;

  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, ws->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*)( ((char*)inpacket) + 96 );
      hash  = (ot_hash*)( ((char*)inpacket) + 16 );

      OT_SETIP( &peer, remoteip );
      OT_SETPORT( &peer, &port );
      OT_PEERFLAG( &peer ) = 0;

      switch( event ) {
        case 1: OT_PEERFLAG( &peer ) |= PEER_FLAG_COMPLETED; break;
        case 3: OT_PEERFLAG( &peer ) |= PEER_FLAG_STOPPED; break;
        default: break;
      }

      if( !left )
        OT_PEERFLAG( &peer )         |= PEER_FLAG_SEEDING;

      outpacket[0] = htonl( 1 );    /* announce action */
      outpacket[1] = inpacket[12/4];

      if( OT_PEERFLAG( &peer ) & PEER_FLAG_STOPPED ) /* Peer is gone. */
        r = remove_peer_from_torrent( hash, &peer, ws->outbuf, FLAG_UDP );
      else
        r = 8 + add_peer_to_torrent_and_return_peers( hash, &peer, FLAG_UDP, numwant, ((char*)outpacket) + 8 );

      socket_send4( serversocket, ws->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*)( ((char*)inpacket) + 16 + 20 * r_out ), ((char*)outpacket) + 8 + 12 * r_out );

      socket_send4( serversocket, ws->outbuf, 8 + 12 * r_out, remoteip, remoteport );
      stats_issue_event( EVENT_SCRAPE, FLAG_UDP, r );
      break;
  }
}

void udp_init( ) {

}

const char *g_version_udp_c = "$Source$: $Revision$\n";