transmission/libtransmission/torrent-magnet.c

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/*
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* This file Copyright (C) 2009 Mnemosyne LLC
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*
* This file is licensed by the GPL version 2. Works owned by the
* Transmission project are granted a special exemption to clause 2(b)
* so that the bulk of its code can remain under the MIT license.
* This exemption does not extend to derived works not owned by
* the Transmission project.
*
* $Id:$
*/
#include <assert.h>
#include <event.h> /* struct evbuffer */
#include "transmission.h"
#include "bencode.h"
#include "crypto.h"
#include "magnet.h"
#include "metainfo.h"
#include "torrent.h"
#include "torrent-magnet.h"
#include "utils.h"
#include "web.h"
#define dbgmsg( tor, ... ) \
do { \
if( tr_deepLoggingIsActive( ) ) \
tr_deepLog( __FILE__, __LINE__, tor->info.name, __VA_ARGS__ ); \
} while( 0 )
/***
****
***/
enum
{
/* don't ask for the same metadata piece more than this often */
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MIN_REPEAT_INTERVAL_SECS = 3
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};
struct metadata_node
{
time_t requestedAt;
int piece;
};
struct tr_incomplete_metadata
{
uint8_t * metadata;
int metadata_size;
int pieceCount;
/** sorted from least to most recently requested */
struct metadata_node * piecesNeeded;
int piecesNeededCount;
};
static void
incompleteMetadataFree( struct tr_incomplete_metadata * m )
{
tr_free( m->metadata );
tr_free( m->piecesNeeded );
tr_free( m );
}
void
tr_torrentSetMetadataSizeHint( tr_torrent * tor, int size )
{
if( !tr_torrentHasMetadata( tor ) )
{
if( tor->incompleteMetadata == NULL )
{
int i;
struct tr_incomplete_metadata * m;
int n = ( size + ( METADATA_PIECE_SIZE - 1 ) ) / METADATA_PIECE_SIZE;
dbgmsg( tor, "there are %d pieces", n );
m = tr_new( struct tr_incomplete_metadata, 1 );
m->pieceCount = n;
m->metadata = tr_new( uint8_t, size );
m->metadata_size = size;
m->piecesNeededCount = n;
m->piecesNeeded = tr_new( struct metadata_node, n );
for( i=0; i<n; ++i ) {
m->piecesNeeded[i].piece = i;
m->piecesNeeded[i].requestedAt = 0;
}
tor->incompleteMetadata = m;
}
}
}
void*
tr_torrentGetMetadataPiece( const tr_torrent * tor, int piece, int * len )
{
char * ret = NULL;
assert( tr_isTorrent( tor ) );
assert( piece >= 0 );
assert( len != NULL );
if( tor->infoDictLength > 0 )
{
FILE * fp = fopen( tor->info.torrent, "rb" );
if( fp != NULL )
{
const int o = piece * METADATA_PIECE_SIZE;
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if( !fseek( fp, tor->infoDictOffset + o, SEEK_SET ) )
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{
const int l = o + METADATA_PIECE_SIZE <= tor->infoDictLength
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? METADATA_PIECE_SIZE
: tor->infoDictLength - o;
if( 0<l && l<=METADATA_PIECE_SIZE )
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{
char * buf = tr_new( char, l );
const int n = fread( buf, 1, l, fp );
if( n == l )
{
*len = l;
ret = buf;
buf = NULL;
}
tr_free( buf );
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}
}
fclose( fp );
}
}
return ret;
}
void
tr_torrentSetMetadataPiece( tr_torrent * tor,
int piece,
const void * data,
int len )
{
int i;
struct tr_incomplete_metadata * m;
const int offset = piece * METADATA_PIECE_SIZE;
assert( tr_isTorrent( tor ) );
dbgmsg( tor, "got metadata piece %d", piece );
/* are we set up to download metadata? */
m = tor->incompleteMetadata;
if( m == NULL )
return;
/* does this data pass the smell test? */
if( offset + len > m->metadata_size )
return;
/* do we need this piece? */
for( i=0; i<m->piecesNeededCount; ++i )
if( m->piecesNeeded[i].piece == piece )
break;
if( i==m->piecesNeededCount )
return;
memcpy( m->metadata + offset, data, len );
tr_removeElementFromArray( m->piecesNeeded, i,
sizeof( struct metadata_node ),
m->piecesNeededCount-- );
dbgmsg( tor, "saving metainfo piece %d... %d remain", piece, m->piecesNeededCount );
/* are we done? */
if( m->piecesNeededCount == 0 )
{
tr_bool success = FALSE;
uint8_t sha1[SHA_DIGEST_LENGTH];
dbgmsg( tor, "metainfo piece %d was the last one", piece );
tr_sha1( sha1, m->metadata, m->metadata_size, NULL );
if( !memcmp( sha1, tor->info.hash, SHA_DIGEST_LENGTH ) )
{
int err;
tr_benc dict;
struct evbuffer * buf = evbuffer_new( );
dbgmsg( tor, "metadata checksum passed! (length: %d)", (int)m->metadata_size );
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/* add a wrapper dictionary to the benc.
* include the announce-list too,
* so we can save it in the .torrent for future sessions */
evbuffer_add_printf( buf, "d" );
evbuffer_add_printf( buf, "13:announce-list" );
evbuffer_add_printf( buf, "l" );
for( i=0; i<tor->info.trackerCount; ++i ) {
const char * url = tor->info.trackers[i].announce;
evbuffer_add_printf( buf, "l%zu:%se", strlen( url ), url );
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}
evbuffer_add_printf( buf, "e" );
evbuffer_add_printf( buf, "4:info" );
evbuffer_add( buf, m->metadata, m->metadata_size );
evbuffer_add_printf( buf, "e" );
/* does it parse? */
err = tr_bencLoad( EVBUFFER_DATA( buf ), EVBUFFER_LENGTH( buf ), &dict, NULL );
dbgmsg( tor, "err is %d", err );
if( !err )
{
if( tr_metainfoParse( tor->session,
&tor->info,
&tor->infoDictOffset,
&tor->infoDictLength,
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&dict ) )
{
const char * path = tor->info.torrent;
dbgmsg( tor, "saving completed metadata to \"%s\"", path );
success = TRUE;
tr_torrentGotNewInfoDict( tor );
tr_bencToFile( &dict, TR_FMT_BENC, path );
tr_sessionSetTorrentFile( tor->session,
tor->info.hashString, path );
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tr_torrentSetDirty( tor );
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}
tr_bencFree( &dict );
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}
evbuffer_free( buf );
}
if( success )
{
incompleteMetadataFree( tor->incompleteMetadata );
tor->incompleteMetadata = NULL;
}
else /* drat. */
{
const int n = m->pieceCount;
for( i=0; i<n; ++i ) {
m->piecesNeeded[i].piece = i;
m->piecesNeeded[i].requestedAt = 0;
}
m->piecesNeededCount = n;
dbgmsg( tor, "metadata error; trying again. %d pieces left", n );
}
}
}
tr_bool
tr_torrentGetNextMetadataRequest( tr_torrent * tor, time_t now, int * setme_piece )
{
tr_bool have_request = FALSE;
struct tr_incomplete_metadata * m;
assert( tr_isTorrent( tor ) );
m = tor->incompleteMetadata;
if( ( m != NULL )
&& ( m->piecesNeededCount > 0 )
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&& ( m->piecesNeeded[0].requestedAt + MIN_REPEAT_INTERVAL_SECS < now ) )
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{
int i;
const int piece = m->piecesNeeded[0].piece;
tr_removeElementFromArray( m->piecesNeeded, 0,
sizeof( struct metadata_node ),
m->piecesNeededCount-- );
i = m->piecesNeededCount++;
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m->piecesNeeded[i].piece = piece;
m->piecesNeeded[i].requestedAt = now;
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dbgmsg( tor, "next piece to request: %d", piece );
*setme_piece = piece;
have_request = TRUE;
}
return have_request;
}
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float
tr_torrentGetMetadataPercent( const tr_torrent * tor )
{
float ret;
if( tr_torrentHasMetadata( tor ) )
ret = 1.0;
else {
const struct tr_incomplete_metadata * m = tor->incompleteMetadata;
if( m == NULL )
ret = 0.0;
else
ret = (m->pieceCount - m->piecesNeededCount) / (float)m->pieceCount;
}
return ret;
}
char*
tr_torrentGetMagnetLink( const tr_torrent * tor )
{
int i;
char * ret;
struct evbuffer * s;
assert( tr_isTorrent( tor ) );
s = evbuffer_new( );
evbuffer_add_printf( s, "magnet:?xt=urn:btih:%s", tor->info.hashString );
evbuffer_add_printf( s, "%s", "&dn=" );
tr_http_escape( s, tr_torrentName( tor ), -1, TRUE );
for( i=0; i<tor->info.trackerCount; ++i )
{
evbuffer_add_printf( s, "%s", "&tr=" );
tr_http_escape( s, tor->info.trackers[i].announce, -1, TRUE );
}
ret = tr_strndup( EVBUFFER_DATA( s ), EVBUFFER_LENGTH( s ) );
evbuffer_free( s );
return ret;
}