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-rw-r--r--ot_udp.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/ot_udp.c b/ot_udp.c
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1/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
2 It is considered beerware. Prost. Skol. Cheers or whatever. */
3
4/* System */
5#include <string.h>
6
7/* Libowfat */
8#include "socket.h"
9#include "io.h"
10
11/* Opentracker */
12#include "trackerlogic.h"
13#include "ot_udp.h"
14#include "ot_stats.h"
15
16/* UDP implementation according to http://xbtt.sourceforge.net/udp_tracker_protocol.html */
17void handle_udp4( int64 serversocket ) {
18 ot_peer peer;
19 ot_torrent *torrent;
20 ot_hash *hash = NULL;
21 char remoteip[4];
22 ot_dword *inpacket = (ot_dword*)static_inbuf;
23 ot_dword *outpacket = (ot_dword*)static_outbuf;
24 ot_dword numwant, left, event;
25 ot_word port, remoteport;
26 size_t r, r_out;
27
28 r = socket_recv4( serversocket, static_inbuf, sizeof( static_inbuf ), remoteip, &remoteport);
29
30 stats_issue_event( EVENT_ACCEPT, 0, 0 );
31 stats_issue_event( EVENT_READ, 0, r );
32
33 /* Minimum udp tracker packet size, also catches error */
34 if( r < 16 )
35 return;
36
37 /* look for udp bittorrent magic id */
38 if( (ntohl(inpacket[0]) != 0x00000417) || (ntohl(inpacket[1]) != 0x27101980) )
39 return;
40
41 switch( ntohl( inpacket[2] ) ) {
42 case 0: /* This is a connect action */
43 outpacket[0] = 0; outpacket[1] = inpacket[3];
44 outpacket[2] = inpacket[0]; outpacket[3] = inpacket[1];
45 socket_send4( serversocket, static_outbuf, 16, remoteip, remoteport );
46 stats_issue_event( EVENT_CONNECT, 0, 16 );
47 break;
48 case 1: /* This is an announce action */
49 /* Minimum udp announce packet size */
50 if( r < 98 )
51 return;
52
53 numwant = 200;
54 /* We do only want to know, if it is zero */
55 left = inpacket[64/4] | inpacket[68/4];
56
57 event = ntohl( inpacket[80/4] );
58 port = *(ot_word*)( static_inbuf + 96 );
59 hash = (ot_hash*)( static_inbuf + 16 );
60
61 OT_SETIP( &peer, remoteip );
62 OT_SETPORT( &peer, &port );
63 OT_FLAG( &peer ) = 0;
64
65 switch( event ) {
66 case 1: OT_FLAG( &peer ) |= PEER_FLAG_COMPLETED; break;
67 case 3: OT_FLAG( &peer ) |= PEER_FLAG_STOPPED; break;
68 default: break;
69 }
70
71 if( !left )
72 OT_FLAG( &peer ) |= PEER_FLAG_SEEDING;
73
74 outpacket[0] = htonl( 1 ); /* announce action */
75 outpacket[1] = inpacket[12/4];
76
77 if( OT_FLAG( &peer ) & PEER_FLAG_STOPPED ) /* Peer is gone. */
78 r = remove_peer_from_torrent( hash, &peer, static_outbuf, 0 );
79 else {
80 torrent = add_peer_to_torrent( hash, &peer WANT_TRACKER_SYNC_PARAM( 0 ) );
81 if( !torrent )
82 return; /* XXX maybe send error */
83
84 r = 8 + return_peers_for_torrent( hash, numwant, static_outbuf + 8, 0 );
85 }
86
87 socket_send4( serversocket, static_outbuf, r, remoteip, remoteport );
88 stats_issue_event( EVENT_ANNOUNCE, 0, r );
89 break;
90
91 case 2: /* This is a scrape action */
92 outpacket[0] = htonl( 2 ); /* scrape action */
93 outpacket[1] = inpacket[12/4];
94
95 for( r_out = 0; ( r_out * 20 < r - 16) && ( r_out <= 74 ); r_out++ )
96 return_udp_scrape_for_torrent( (ot_hash*)( static_inbuf + 16 + 20 * r_out ), static_outbuf + 8 + 12 * r_out );
97
98 socket_send4( serversocket, static_outbuf, 8 + 12 * r_out, remoteip, remoteport );
99 stats_issue_event( EVENT_SCRAPE, 0, r );
100 break;
101 }
102}