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