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transmission/libtransmission/peerutils.h

396 lines
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/******************************************************************************
* $Id$
*
* Copyright (c) 2005-2006 Transmission authors and contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*****************************************************************************/
static void updateInterest( tr_torrent_t * tor, tr_peer_t * peer );
/***********************************************************************
* peerInit
***********************************************************************
* Allocates a new tr_peer_t and returns a pointer to it.
**********************************************************************/
static tr_peer_t * peerInit()
{
tr_peer_t * peer;
peer = calloc( sizeof( tr_peer_t ), 1 );
peer->amChoking = 1;
peer->peerChoking = 1;
peer->date = tr_date();
peer->keepAlive = peer->date;
peer->download = tr_rcInit();
peer->upload = tr_rcInit();
return peer;
}
/***********************************************************************
* peerAttach
***********************************************************************
* Deallocates the tr_peer_t and returns 0 if we reached the maximum
* authorized number of peers. Otherwise, adds the tr_peer_t to the
* peers list.
**********************************************************************/
static int peerAttach( tr_torrent_t * tor, tr_peer_t * peer )
{
if( tor->peerCount >= TR_MAX_PEER_COUNT )
{
tr_peerDestroy( tor->fdlimit, peer );
return 0;
}
tor->peers[tor->peerCount++] = peer;
return 1;
}
static int peerCmp( tr_peer_t * peer1, tr_peer_t * peer2 )
{
/* Wait until we got the peers' ids */
if( peer1->status < PEER_STATUS_CONNECTED ||
peer2->status < PEER_STATUS_CONNECTED )
{
return 1;
}
return memcmp( peer1->id, peer2->id, 20 );
}
/***********************************************************************
* addWithAddr
***********************************************************************
* Does nothing if we already have a peer matching 'addr' and 'port'.
* Otherwise adds such a new peer.
**********************************************************************/
static void addWithAddr( tr_torrent_t * tor, struct in_addr addr,
in_port_t port )
{
int i;
tr_peer_t * peer;
for( i = 0; i < tor->peerCount; i++ )
{
peer = tor->peers[i];
if( peer->addr.s_addr == addr.s_addr &&
peer->port == port )
{
/* We are already connected to this peer */
return;
}
}
peer = peerInit();
if( !peerAttach( tor, peer ) )
{
return;
}
peer->addr = addr;
peer->port = port;
peer->status = PEER_STATUS_IDLE;
}
static int checkPeer( tr_torrent_t * tor, int i )
{
tr_peer_t * peer = tor->peers[i];
if( peer->status < PEER_STATUS_CONNECTED &&
tr_date() > peer->date + 8000 )
{
/* If it has been too long, don't wait for the socket
to timeout - forget about it now */
peer_dbg( "connection timeout" );
return 1;
}
/* Drop peers who haven't even sent a keep-alive within the
last 3 minutes */
if( tr_date() > peer->date + 180000 )
{
peer_dbg( "read timeout" );
return 1;
}
/* Drop peers which are supposed to upload but actually
haven't sent anything within the last minute */
if( peer->inRequestCount && tr_date() > peer->date + 60000 )
{
peer_dbg( "bad uploader" );
return 1;
}
if( peer->status & PEER_STATUS_CONNECTED )
{
/* Send keep-alive every 2 minutes */
if( tr_date() > peer->keepAlive + 120000 )
{
sendKeepAlive( peer );
peer->keepAlive = tr_date();
}
}
/* Connect */
if( ( peer->status & PEER_STATUS_IDLE ) &&
!tr_fdSocketWillCreate( tor->fdlimit, 0 ) )
{
peer->socket = tr_netOpenTCP( peer->addr, peer->port );
if( peer->socket < 0 )
{
peer_dbg( "connection failed" );
tr_fdSocketClosed( tor->fdlimit, 0 );
return 1;
}
peer->status = PEER_STATUS_CONNECTING;
}
/* Try to send handshake */
if( peer->status & PEER_STATUS_CONNECTING )
{
uint8_t buf[68];
tr_info_t * inf = &tor->info;
int ret;
buf[0] = 19;
memcpy( &buf[1], "BitTorrent protocol", 19 );
memset( &buf[20], 0, 8 );
memcpy( &buf[28], inf->hash, 20 );
memcpy( &buf[48], tor->id, 20 );
ret = tr_netSend( peer->socket, buf, 68 );
if( ret & TR_NET_CLOSE )
{
peer_dbg( "connection closed" );
return 1;
}
else if( !( ret & TR_NET_BLOCK ) )
{
peer_dbg( "SEND handshake" );
peer->status = PEER_STATUS_HANDSHAKE;
}
}
return 0;
}
/***********************************************************************
* isInteresting
***********************************************************************
* Returns 1 if 'peer' has at least one piece that we haven't completed,
* or 0 otherwise.
**********************************************************************/
static int isInteresting( tr_torrent_t * tor, tr_peer_t * peer )
{
tr_info_t * inf = &tor->info;
int i;
int bitfieldSize = ( inf->pieceCount + 7 ) / 8;
uint8_t * bitfield = tr_cpPieceBitfield( tor->completion );
if( !peer->bitfield )
{
/* We don't know what this peer has */
return 0;
}
for( i = 0; i < bitfieldSize; i++ )
{
if( ( peer->bitfield[i] & ~(bitfield[i]) ) & 0xFF )
{
return 1;
}
}
return 0;
}
static void updateInterest( tr_torrent_t * tor, tr_peer_t * peer )
{
int interested = isInteresting( tor, peer );
if( interested && !peer->amInterested )
{
sendInterest( peer, 1 );
}
if( !interested && peer->amInterested )
{
sendInterest( peer, 0 );
}
}
/***********************************************************************
* chooseBlock
***********************************************************************
* At this point, we know the peer has at least one block we have an
* interest in. If he has more than one, we choose which one we are
* going to ask first.
* Our main goal is to complete pieces, so we look the pieces which are
* missing less blocks.
**********************************************************************/
static inline int chooseBlock( tr_torrent_t * tor, tr_peer_t * peer )
{
tr_info_t * inf = &tor->info;
int i;
int missingBlocks, minMissing;
int poolSize, * pool;
int block, minDownloading;
/* Choose a piece */
pool = malloc( inf->pieceCount * sizeof( int ) );
poolSize = 0;
minMissing = tor->blockCount + 1;
for( i = 0; i < inf->pieceCount; i++ )
{
missingBlocks = tr_cpMissingBlocksForPiece( tor->completion, i );
if( missingBlocks < 1 )
{
/* We already have or are downloading all blocks */
continue;
}
if( !tr_bitfieldHas( peer->bitfield, i ) )
{
/* The peer doesn't have this piece */
continue;
}
if( peer->banfield && tr_bitfieldHas( peer->banfield, i ) )
{
/* The peer is banned for this piece */
continue;
}
/* We are interested in this piece, remember it */
if( missingBlocks < minMissing )
{
minMissing = missingBlocks;
poolSize = 0;
}
if( missingBlocks <= minMissing )
{
pool[poolSize++] = i;
}
}
if( poolSize )
{
/* All pieces in 'pool' have 'minMissing' missing blocks. Find
the rarest ones. */
uint8_t * bitfield;
int piece;
int min, foo, j;
int * pool2;
int pool2Size;
pool2 = malloc( poolSize * sizeof( int ) );
pool2Size = 0;
min = TR_MAX_PEER_COUNT + 1;
for( i = 0; i < poolSize; i++ )
{
foo = 0;
for( j = 0; j < tor->peerCount; j++ )
{
bitfield = tor->peers[j]->bitfield;
if( bitfield && tr_bitfieldHas( bitfield, pool[i] ) )
{
foo++;
}
}
if( foo < min )
{
min = foo;
pool2Size = 0;
}
if( foo <= min )
{
pool2[pool2Size++] = pool[i];
}
}
free( pool );
if( pool2Size < 1 )
{
/* Shouldn't happen */
free( pool2 );
return -1;
}
/* All pieces in pool2 have the same number of missing blocks,
and are availabme from the same number of peers. Pick a
random one */
piece = pool2[tr_rand(pool2Size)];
free( pool2 );
/* Pick a block in this piece */
block = tr_cpMissingBlockInPiece( tor->completion, piece );
goto check;
}
free( pool );
/* "End game" mode */
minDownloading = 255;
block = -1;
for( i = 0; i < inf->pieceCount; i++ )
{
int downloaders, block2;
if( !tr_bitfieldHas( peer->bitfield, i ) )
{
/* The peer doesn't have this piece */
continue;
}
if( peer->banfield && tr_bitfieldHas( peer->banfield, i ) )
{
/* The peer is banned for this piece */
continue;
}
if( tr_cpPieceIsComplete( tor->completion, i ) )
{
/* We already have it */
continue;
}
block2 = tr_cpMostMissingBlockInPiece( tor->completion, i, &downloaders );
if( block2 > -1 && downloaders < minDownloading )
{
block = block2;
minDownloading = downloaders;
}
}
check:
if( block < 0 )
{
/* Shouldn't happen */
return -1;
}
for( i = 0; i < peer->inRequestCount; i++ )
{
tr_request_t * r;
r = &peer->inRequests[i];
if( tr_block( r->index, r->begin ) == block )
{
/* We are already asking this peer for this block */
return -1;
}
}
return block;
}
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