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Live syncing between multiple tracker instances via udp multicast.

master
Dirk Engling 13 years ago
parent
commit
de7ee67519
  1. 122
      ot_livesync.c
  2. 85
      ot_livesync.h

122
ot_livesync.c

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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 <sys/types.h>
#include <sys/uio.h>
#include <string.h>
/* Libowfat */
#include "socket.h"
/* Opentracker */
#include "trackerlogic.h"
#include "ot_livesync.h"
#include "ot_accesslist.h"
#ifdef WANT_SYNC_LIVE
char groupip_1[4] = { LIVESYNC_MCASTDOMAIN_1 };
/* For outgoing packets */
int64 g_livesync_socket = -1;
static uint8_t livesync_inbuffer[LIVESYNC_BUFFINSIZE];
static uint8_t livesync_outbuffer_start[ LIVESYNC_BUFFSIZE ];
static uint8_t *livesync_outbuffer_pos;
static uint8_t *livesync_outbuffer_highwater = livesync_outbuffer_start + LIVESYNC_BUFFSIZE - LIVESYNC_BUFFWATER;
static ot_time livesync_lastpacket_time;
void livesync_init( ) {
if( g_livesync_socket == -1 )
exerr( "No socket address for live sync specified." );
livesync_outbuffer_pos = livesync_outbuffer_start;
memmove( livesync_outbuffer_pos, &g_tracker_id, sizeof( g_tracker_id ) );
livesync_outbuffer_pos += sizeof( g_tracker_id );
livesync_lastpacket_time = g_now;
}
void livesync_deinit() {
}
void livesync_bind_mcast( char *ip, uint16_t port) {
char tmpip[4] = {0,0,0,0};
if( g_livesync_socket != -1 )
exerr("Livesync listen ip specified twice.");
if( socket_mcjoin4( ot_try_bind(tmpip, port, FLAG_MCA ), groupip_1, ip ) )
exerr("Cant join mcast group.");
g_livesync_socket = ot_try_bind( ip, port, FLAG_UDP );
io_dontwantread(g_livesync_socket);
socket_mcttl4(g_livesync_socket, 1);
socket_mcloop4(g_livesync_socket, 0);
}
static void livesync_issuepacket( ) {
socket_send4(g_livesync_socket, (char*)livesync_outbuffer_start, livesync_outbuffer_pos - livesync_outbuffer_start,
groupip_1, LIVESYNC_PORT);
livesync_outbuffer_pos = livesync_outbuffer_start + sizeof( g_tracker_id );
livesync_lastpacket_time = g_now;
}
/* Inform live sync about whats going on. */
void livesync_tell( ot_hash * const info_hash, const ot_peer * const peer, const uint8_t peerflag ) {
memmove( livesync_outbuffer_pos , info_hash, sizeof(ot_hash));
memmove( livesync_outbuffer_pos + sizeof(ot_hash), peer, sizeof(ot_peer));
OT_FLAG( livesync_outbuffer_pos + sizeof(ot_hash) ) |= peerflag;
livesync_outbuffer_pos += sizeof(ot_hash) + sizeof(ot_peer);
if( livesync_outbuffer_pos >= livesync_outbuffer_highwater )
livesync_issuepacket();
}
/* Tickle the live sync module from time to time, so no events get
stuck when there's not enough traffic to fill udp packets fast
enough */
void livesync_ticker( ) {
if( ( g_now - livesync_lastpacket_time > LIVESYNC_MAXDELAY) &&
( livesync_outbuffer_pos > livesync_outbuffer_start + sizeof( g_tracker_id ) ) )
livesync_issuepacket();
}
/* Handle an incoming live sync packet */
void handle_livesync( int64 serversocket ) {
uint8_t in_ip[4]; uint16_t in_port;
ssize_t datalen = socket_recv4(serversocket, (char*)livesync_inbuffer, LIVESYNC_BUFFINSIZE, (char*)in_ip, &in_port);
int off = 4;
if( datalen < (ssize_t)(sizeof( g_tracker_id ) + sizeof( ot_hash ) + sizeof( ot_peer ) ) ) {
// TODO: log invalid sync packet
return;
}
if( !accesslist_isblessed((char*)in_ip, OT_PERMISSION_MAY_LIVESYNC)) {
// TODO: log invalid sync packet
return;
}
if( !memcmp( livesync_inbuffer, &g_tracker_id, sizeof( g_tracker_id ) ) ) {
// TODO: log packet coming from ourselves
return;
}
// Now basic sanity checks have been done on the live sync packet
// We might add more testing and logging.
while( off + (ssize_t)sizeof( ot_hash ) + (ssize_t)sizeof( ot_peer ) <= datalen ) {
ot_peer *peer = (ot_peer*)(livesync_inbuffer + off + sizeof(ot_hash));
ot_hash *hash = (ot_hash*)(livesync_inbuffer + off);
if( OT_FLAG(peer) & PEER_FLAG_STOPPED )
remove_peer_from_torrent(hash, peer, NULL, FLAG_MCA);
else
add_peer_to_torrent( hash, peer WANT_SYNC_PARAM(1));
off += sizeof( ot_hash ) + sizeof( ot_peer );
}
}
#endif
const char *g_version_livesync_c = "$Source: /home/cvsroot/opentracker/ot_livesync.c,v $: $Revision: 1.1 $\n";

85
ot_livesync.h

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/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
It is considered beerware. Prost. Skol. Cheers or whatever.
$id$ */
#ifndef __OT_LIVESYNC_H__
#define __OT_LIVESYNC_H__
#include "io.h"
#include "trackerlogic.h"
/*
Syncing is done as udp packets in the multicast domain 224.23.42.N port 9696
Each tracker should join the multicast group and send its live sync packets
to that group, using a ttl of 1
Format of a live sync packet is straight forward and depends on N:
For N == 1: (simple tracker2tracker sync)
0x0000 0x04 id of tracker instance
[ 0x0004 0x14 info_hash
0x0018 0x04 peer's ipv4 address
0x001c 0x02 peer's port
0x0020 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
]*
For N == 2: (aggregator syncs)
0x0000 0x04 id of tracker instance
[ 0x0004 0x14 info_hash
0x0018 0x01 number of peers
[ 0x0019 0x04 peer's ipv4 address
0x001a 0x02 peer's port
0x0021 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
]+
]*
*/
#ifdef WANT_SYNC_LIVE
#define LIVESYNC_PORT 9696
#define LIVESYNC_MCASTDOMAIN_1 224,23,42,1
#define LIVESYNC_MCASTDOMAIN_2 224,23,42,2
extern char groupip_1[4];
extern char groupip_2[4];
extern int64 g_livesync_socket;
#define LIVESYNC_BUFFINSIZE (256*256)
#define LIVESYNC_BUFFSIZE 1504
#define LIVESYNC_BUFFWATER (sizeof(ot_peer)+sizeof(ot_hash))
#define LIVESYNC_MAXDELAY 15
void livesync_init();
void livesync_deinit();
/* Join multicast group for listening and create sending socket */
void livesync_bind_mcast( char *ip, uint16_t port );
/* Inform live sync about whats going on. */
void livesync_tell( ot_hash * const info_hash, const ot_peer * const peer, const uint8_t peerflag );
/* Tickle the live sync module from time to time, so no events get
stuck when there's not enough traffic to fill udp packets fast
enough */
void livesync_ticker( );
/* Handle an incoming live sync packet */
void handle_livesync( const int64 serversocket );
#else
/* If no syncing is required, save calling code from #ifdef
constructions */
#define livesync_init()
#define livesync_ticker()
#define handle_livesync(a)
#endif
#endif
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