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transmission/libtransmission/torrent-magnet.c

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/*
* This file Copyright (C) Mnemosyne LLC
*
* 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 <stdio.h> /* remove() */
#include <string.h> /* memcpy(), memset(), memcmp() */
#include <event2/buffer.h>
#include "transmission.h"
#include "bencode.h"
#include "crypto.h" /* tr_sha1() */
#include "magnet.h"
#include "metainfo.h"
#include "resume.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 */
MIN_REPEAT_INTERVAL_SECS = 3
};
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;
const int n = ( size + ( METADATA_PIECE_SIZE - 1 ) ) / METADATA_PIECE_SIZE;
dbgmsg( tor, "metadata is %d bytes in %d pieces", size, 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;
}
}
}
static int
findInfoDictOffset( const tr_torrent * tor )
{
size_t fileLen;
uint8_t * fileContents;
int offset = 0;
/* load the file, and find the info dict's offset inside the file */
if(( fileContents = tr_loadFile( tor->info.torrent, &fileLen )))
{
tr_benc top;
if( !tr_bencParse( fileContents, fileContents + fileLen, &top, NULL ) )
{
tr_benc * infoDict;
if( tr_bencDictFindDict( &top, "info", &infoDict ) )
{
int infoLen;
char * infoContents = tr_bencToStr( infoDict, TR_FMT_BENC, &infoLen );
const uint8_t * i = (const uint8_t*) tr_memmem( (char*)fileContents, fileLen, infoContents, infoLen );
offset = i != NULL ? i - fileContents : 0;
tr_free( infoContents );
}
tr_bencFree( &top );
}
tr_free( fileContents );
}
return offset;
}
static void
ensureInfoDictOffsetIsCached( tr_torrent * tor )
{
assert( tr_torrentHasMetadata( tor ) );
if( !tor->infoDictOffsetIsCached )
{
tor->infoDictOffset = findInfoDictOffset( tor );
tor->infoDictOffsetIsCached = true;
}
}
void*
tr_torrentGetMetadataPiece( tr_torrent * tor, int piece, int * len )
{
char * ret = NULL;
assert( tr_isTorrent( tor ) );
assert( piece >= 0 );
assert( len != NULL );
if( tr_torrentHasMetadata( tor ) )
{
FILE * fp;
ensureInfoDictOffsetIsCached( tor );
assert( tor->infoDictLength > 0 );
assert( tor->infoDictOffset >= 0 );
fp = fopen( tor->info.torrent, "rb" );
if( fp != NULL )
{
const int o = piece * METADATA_PIECE_SIZE;
if( !fseek( fp, tor->infoDictOffset + o, SEEK_SET ) )
{
const int l = o + METADATA_PIECE_SIZE <= tor->infoDictLength
? METADATA_PIECE_SIZE
: tor->infoDictLength - o;
if( 0<l && l<=METADATA_PIECE_SIZE )
{
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 );
}
}
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 )
{
bool success = false;
bool checksumPassed = false;
bool metainfoParsed = false;
uint8_t sha1[SHA_DIGEST_LENGTH];
/* we've got a complete set of metainfo... see if it passes the checksum test */
dbgmsg( tor, "metainfo piece %d was the last one", piece );
tr_sha1( sha1, m->metadata, m->metadata_size, NULL );
if(( checksumPassed = !memcmp( sha1, tor->info.hash, SHA_DIGEST_LENGTH )))
{
/* checksum passed; now try to parse it as benc */
tr_benc infoDict;
const int err = tr_bencLoad( m->metadata, m->metadata_size, &infoDict, NULL );
dbgmsg( tor, "err is %d", err );
if(( metainfoParsed = !err ))
{
/* yay we have bencoded metainfo... merge it into our .torrent file */
tr_benc newMetainfo;
char * path = tr_strdup( tor->info.torrent );
if( !tr_bencLoadFile( &newMetainfo, TR_FMT_BENC, path ) )
{
bool hasInfo;
tr_info info;
int infoDictLength;
/* remove any old .torrent and .resume files */
remove( path );
tr_torrentRemoveResume( tor );
dbgmsg( tor, "Saving completed metadata to \"%s\"", path );
tr_bencMergeDicts( tr_bencDictAddDict( &newMetainfo, "info", 0 ), &infoDict );
memset( &info, 0, sizeof( tr_info ) );
success = tr_metainfoParse( tor->session, &newMetainfo, &info, &hasInfo, &infoDictLength );
if( success && !tr_getBlockSize( info.pieceSize ) )
{
tr_torrentSetLocalError( tor, "%s", _( "Magnet torrent's metadata is not usable" ) );
success = false;
}
if( success )
{
/* keep the new info */
tor->info = info;
tor->infoDictLength = infoDictLength;
/* save the new .torrent file */
tr_bencToFile( &newMetainfo, TR_FMT_BENC, tor->info.torrent );
tr_sessionSetTorrentFile( tor->session, tor->info.hashString, tor->info.torrent );
tr_torrentGotNewInfoDict( tor );
tr_torrentSetDirty( tor );
}
tr_bencFree( &newMetainfo );
}
tr_bencFree( &infoDict );
tr_free( path );
}
}
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_err( "magnet status: checksum passed %d, metainfo parsed %d",
(int)checksumPassed, (int)metainfoParsed );
}
}
}
bool
tr_torrentGetNextMetadataRequest( tr_torrent * tor, time_t now, int * setme_piece )
{
bool have_request = false;
struct tr_incomplete_metadata * m;
assert( tr_isTorrent( tor ) );
m = tor->incompleteMetadata;
if( ( m != NULL )
&& ( m->piecesNeededCount > 0 )
&& ( m->piecesNeeded[0].requestedAt + MIN_REPEAT_INTERVAL_SECS < now ) )
{
int i;
const int piece = m->piecesNeeded[0].piece;
tr_removeElementFromArray( m->piecesNeeded, 0,
sizeof( struct metadata_node ),
m->piecesNeededCount-- );
i = m->piecesNeededCount++;
m->piecesNeeded[i].piece = piece;
m->piecesNeeded[i].requestedAt = now;
dbgmsg( tor, "next piece to request: %d", piece );
*setme_piece = piece;
have_request = true;
}
return have_request;
}
double
tr_torrentGetMetadataPercent( const tr_torrent * tor )
{
double ret;
if( tr_torrentHasMetadata( tor ) )
ret = 1.0;
else {
const struct tr_incomplete_metadata * m = tor->incompleteMetadata;
if( !m || !m->pieceCount )
ret = 0.0;
else
ret = (m->pieceCount - m->piecesNeededCount) / (double)m->pieceCount;
}
return ret;
}
char*
tr_torrentGetMagnetLink( const tr_torrent * tor )
{
int i;
const char * name;
struct evbuffer * s;
assert( tr_isTorrent( tor ) );
s = evbuffer_new( );
evbuffer_add_printf( s, "magnet:?xt=urn:btih:%s", tor->info.hashString );
name = tr_torrentName( tor );
if( name && *name )
{
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 );
}
return evbuffer_free_to_str( s );
}
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