An open and free bittorrent tracker https://erdgeist.org/gitweb/opentracker
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#include "trackerlogic.h"
#include <stdlib.h>
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#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <time.h>
#include <glob.h>
// Helper functions for binary_find
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//
int compare_hash( const void *hash1, const void *hash2 ) { return memcmp( hash1, hash2, sizeof( ot_hash )); }
int compare_ip_port( const void *peer1, const void *peer2 ) { return memcmp( &((ot_peer)peer1)->ip, &((ot_peer)peer2)->ip, 6); }
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void *binary_search( const void *key, const void *base,
unsigned long member_count, const unsigned long member_size,
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int (*compar) (const void *, const void *),
int *exactmatch ) {
ot_byte *lookat = ((ot_byte*)base) + member_size * (member_count >> 1);
*exactmatch = 1;
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while( member_count ) {
int cmp = compar((void*)lookat, key);
if (cmp == 0) return (void *)lookat;
if (cmp < 0) {
base = (void*)(lookat + member_size);
--member_count;
}
member_count >>= 1;
lookat = ((ot_byte*)base) + member_size * (member_count >> 1);
}
*exactmatch = 0;
return (void*)lookat;
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}
// Converter function from memory to human readable hex strings
// * definitely not thread safe!!!
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//
char ths[1+2*20];char *to_hex(ot_byte*s){char*m="0123456789ABCDEF";char*e=ths+40;char*t=ths;while(t<e){*t++=m[*s>>4];*t++=m[*s++&15];}*t=0;return ths;}
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// GLOBAL VARIABLES
//
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unsigned long torrents_count = 0;
ot_torrent torrents_list = 0;
ot_byte *scratch_space = 0;
#define SETINVALID( i ) (scratch_space[index] = 3);
#define SETSELECTED( i ) (scratch_space[index] = 1);
#define TESTSELECTED( i ) (scratch_space[index] == 1 )
#define TESTSET( i ) (scratch_space[index])
#define RANDOM random()
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ot_torrent add_peer_to_torrent( ot_hash hash, ot_peer peer ) {
ot_torrent torrent;
ot_peer peer_dest;
int exactmatch;
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torrent = BINARY_FIND( hash, torrents_list, torrents_count, sizeof( *torrent ), compare_hash, &exactmatch );
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if( !exactmatch ) {
// Assume, OS will provide us with space, after all, this is file backed
MEMMOVE( torrent + 1, torrent, ( torrents_list + torrents_count ) - torrent );
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// Create a new torrent entry, then
MEMMOVE( &torrent->hash, hash, sizeof( ot_hash ) );
torrent->peer_list = map_file( to_hex( hash ) );
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torrent->peer_count = 0;
torrent->seed_count = 0;
}
peer_dest = BINARY_FIND( peer, torrent->peer_list, torrent->peer_count, sizeof( *peer_dest ), compare_ip_port, &exactmatch );
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if( exactmatch ) {
// If peer was a seeder but isn't anymore, decrease seeder count
if( ( peer_dest->flags & PEER_FLAG_SEEDING ) && !( peer->flags & PEER_FLAG_SEEDING ) )
torrent->seed_count--;
if( !( peer_dest->flags & PEER_FLAG_SEEDING ) && ( peer->flags & PEER_FLAG_SEEDING ) )
torrent->seed_count++;
} else {
// Assume, OS will provide us with space, after all, this is file backed
MEMMOVE( peer_dest + 1, peer_dest, ( torrent->peer_list + torrent->peer_count ) - peer_dest );
// Create a new peer entry, then
MEMMOVE( peer_dest, peer, sizeof( ot_peer ) );
torrent->peer_count++;
torrent->seed_count+= ( peer->flags & PEER_FLAG_SEEDING ) ? 1 : 0;
}
// Set new time out time
peer_dest->death = NOW + OT_TIMEOUT;
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return torrent;
}
inline int TESTVALIDPEER( ot_peer p ) { return p->death > NOW; }
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// Compiles a list of random peers for a torrent
// * scratch space keeps track of death or already selected peers
// * reply must have enough space to hold 1+(1+16+2+1)*amount+1 bytes
// * Selector function can be anything, maybe test for seeds, etc.
// * that RANDOM may return huge values
// * does not yet check not to return self
// * it is not guaranteed to see all peers, so no assumptions on active seeders/peers may be done
// * since compact format cannot handle v6 addresses, it must be enabled by OT_COMPACT_ONLY
//
void return_peers_for_torrent( ot_torrent torrent, unsigned long amount, char *reply ) {
register ot_peer peer_base = torrent->peer_list;
unsigned long peer_count = torrent->peer_count;
unsigned long selected_count = 0, invalid_count = 0;
unsigned long index = 0;
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// optimize later ;)
BZERO( scratch_space, peer_count );
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while( ( selected_count < amount ) && ( selected_count + invalid_count < peer_count ) ) {
// skip to first non-flagged peer
while( TESTSET(index) ) index = ( index + 1 ) % peer_count;
if( TESTVALIDPEER( peer_base + index ) ) {
SETINVALID(index); invalid_count++;
} else {
SETSELECTED(index); selected_count++;
index = ( index + RANDOM ) % peer_count;
}
}
// Now our scratchspace contains a list of selected_count valid peers
// Collect them into a reply string
index = 0;
#ifndef OT_COMPACT_ONLY
reply += FORMAT_FIXED_STRING( reply, "d5:peersl" );
#else
reply += FORMAT_FORMAT_STRING( reply, "d5:peers%li:",6*selected_count );
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#endif
while( selected_count-- ) {
ot_peer peer;
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while( !TESTSELECTED( index ) ) ++index;
peer = peer_base + index;
#ifdef OT_COMPACT_ONLY
MEMMOVE( reply, &peer->ip, 4 );
MEMMOVE( reply+4, &peer->port, 2 );
reply += 6;
#else
reply += FORMAT_FORMAT_STRING( reply, "d2:ip%d:%s7:peer id20:%20c4:porti%ie",
peer->flags & PEER_IP_LENGTH_MASK,
peer->ip,
peer->id,
peer->port );
#endif
}
#ifndef OT_COMPACT_ONLY
reply += FORMAT_FIXED_STRING( reply, "ee" );
#else
reply += FORMAT_FIXED_STRING( reply, "e" );
#endif
}
// Compacts a torrents peer list
// * torrents older than OT_TIMEOUT are being kicked
// * is rather expansive
// * if this fails, torrent file is invalid, should add flag
//
void heal_torrent( ot_torrent torrent ) {
unsigned long index = 0, base = 0, end, seed_count = 0, now = NOW;
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// Initialize base to first dead peer.
while( ( base < torrent->peer_count ) && torrent->peer_list[base].death <= now ) {
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seed_count += ( torrent->peer_list[base].flags & PEER_FLAG_SEEDING ) ? 1 : 0;
base++;
}
// No dead peers? Home.
if( base == torrent->peer_count ) return;
// From now index always looks to the next living peer while base keeps track of
// the dead peer that marks the beginning of insert space.
index = base + 1;
while( 1 ) {
// Let index search for next living peer
while( ( index < torrent->peer_count ) && torrent->peer_list[index].death > now ) index++;
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// No further living peers found - base is our new peer count
if( index == torrent->peer_count ) {
torrent->peer_count = base;
torrent->seed_count = seed_count;
return;
}
end = index + 1;
// Let end search for next dead peer (end of living peers)
while( ( end < torrent->peer_count ) && torrent->peer_list[end].death <= now ) {
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seed_count += ( torrent->peer_list[end].flags & PEER_FLAG_SEEDING ) ? 1 : 0;
end++;
}
// We either hit a dead peer or the end of our peers
// In both cases: move block towards base
MEMMOVE( torrent->peer_list + base, torrent->peer_list + index, ( end - index ) * sizeof( struct ot_peer ) );
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base += end - index;
index = end;
}
}
void dispose_torrent( ot_torrent torrent ) {
unmap_file( "", torrent->peer_list, 0 );
unlink( to_hex( torrent->hash ) );
MEMMOVE( torrent, torrent + 1, ( torrents_list + torrents_count ) - ( torrent + 1 ) );
torrents_count--;
}
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// This function maps a "huge" file into process space
// * giving no name will aqcuire anonymous growable memory
// * memory will not be "freed" from systems vm if once used, until unmap_file
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// * I guess, we should be checking for more errors...
//
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void *map_file( char *file_name ) {
char *map;
if( file_name ) {
int file_desc=open(file_name,O_RDWR|O_CREAT|O_NDELAY,0644);
if( file_desc < 0) return 0;
lseek( file_desc, OT_HUGE_FILESIZE, SEEK_SET );
map=mmap(0,OT_HUGE_FILESIZE,PROT_READ|PROT_WRITE,MAP_SHARED,file_desc,0);
close(file_desc);
} else
map=mmap(0,OT_HUGE_FILESIZE,PROT_READ|PROT_WRITE,MAP_ANON,-1,0);
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return (map == (char*)-1) ? 0 : map;
}
void unmap_file( char *file_name, void *map, unsigned long real_size ) {
munmap( map, OT_HUGE_FILESIZE );
if( file_name)
truncate( file_name, real_size );
}
void count_peers_and_seeds( ot_peer peer_list, unsigned long *peers, unsigned long *seeds ) {
*peers = *seeds = 0;
if( peer_list[*peers].ip )
do {
*seeds += peer_list[*peers++].flags & PEER_FLAG_SEEDING ? 1 : 0;
} while( compare_ip_port( peer_list + *peers, peer_list + *peers - 1 ) < 0 );
}
int init_logic( char *directory ) {
glob_t globber;
int i;
if( directory )
chdir( directory );
scratch_space = map_file( "" );
torrents_list = map_file( "" );
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torrents_count = 0;
if( !scratch_space || !torrents_list ) {
if( scratch_space || torrents_list )
unmap_file( "", scratch_space ? (void*)scratch_space : (void*)torrents_list, 0 );
return -1;
}
// Scan directory for filenames in the form [0-9A-F]{20}
// * I know this looks ugly, but I've seen A-F to match umlauts as well in strange locales
// * lower case for .. better being safe than sorry, this is not expansive here :)
if( !glob(
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
"[0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef][0-9ABCDEFabcdef]"
, GLOB_NOCHECK, 0, &globber) )
{
for( i=0; i<globber.gl_matchc; ++i ) {
#ifdef _DEBUG
printf( "Found dir: %s\n", globber.gl_pathv[i] );
#endif
if( ( torrents_list[torrents_count].peer_list = map_file( globber.gl_pathv[i] ) ) ) {
MEMMOVE( &torrents_list[torrents_count].hash, globber.gl_pathv[i], sizeof( ot_hash ) );
count_peers_and_seeds( torrents_list[torrents_count].peer_list,
&torrents_list[torrents_count].peer_count,
&torrents_list[torrents_count].seed_count );
torrents_count++;
}
}
}
globfree( &globber );
return 0;
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}
void deinit_logic( ) {
// For all torrents... blablabla
while( torrents_count-- )
unmap_file( to_hex(torrents_list[torrents_count].hash), torrents_list[torrents_count].peer_list, torrents_list[torrents_count].peer_count * sizeof(struct ot_peer) );
unmap_file( "", torrents_list, 0 );
unmap_file( "", scratch_space, 0 );
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}