transmission/libtransmission/magnet.c

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/*
2010-01-04 21:00:47 +00:00
* This file Copyright (C) 2009-2010 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 <string.h> /* strchr() */
#include "transmission.h"
#include "bencode.h"
#include "magnet.h"
#include "utils.h"
#include "web.h"
/***
****
***/
/* this base32 code converted from code by Robert Kaye and Gordon Mohr
* and is public domain. see http://bitzi.com/publicdomain for more info */
static const int base32Lookup[] =
{
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0xFF,0xFF,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F, /* '0', '1', '2', '3', '4', '5', '6', '7' */
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, /* '8', '9', ':', ';', '<', '=', '>', '?' */
0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, /* '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G' */
0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, /* 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O' */
0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, /* 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W' */
0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF, /* 'X', 'Y', 'Z', '[', '\', ']', '^', '_' */
0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, /* '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g' */
0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, /* 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o' */
0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, /* 'p', 'q', 'r', 's', 't', 'u', 'v', 'w' */
0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF /* 'x', 'y', 'z', '{', '|', '}', '~', 'DEL' */
};
static const int base32LookupLen = sizeof( base32Lookup ) / sizeof( base32Lookup[0] );
static void
base32_to_sha1( uint8_t * out, const char * in, const int inlen )
{
const int outlen = 20;
int i, index, offset;
memset( out, 0, 20 );
assert( inlen == 32 );
for( i=0, index=0, offset=0; i<inlen; ++i )
{
int digit;
int lookup = in[i] - '0';
/* Skip chars outside the lookup table */
if( lookup<0 || lookup>=base32LookupLen )
continue;
/* If this digit is not in the table, ignore it */
digit = base32Lookup[lookup];
if( digit == 0xFF )
continue;
if( index <= 3 ) {
index = (index + 5) % 8;
if( index == 0 ) {
out[offset] |= digit;
offset++;
if( offset >= outlen )
break;
} else {
out[offset] |= digit << (8 - index);
}
} else {
index = (index + 5) % 8;
out[offset] |= (digit >> index);
offset++;
if( offset >= outlen )
break;
out[offset] |= digit << (8 - index);
}
}
}
/***
****
***/
#define MAX_TRACKERS 64
#define MAX_WEBSEEDS 64
tr_magnet_info *
tr_magnetParse( const char * uri )
{
tr_bool got_checksum = FALSE;
int trCount = 0;
int wsCount = 0;
char * tr[MAX_TRACKERS];
char * ws[MAX_WEBSEEDS];
char * displayName = NULL;
uint8_t sha1[SHA_DIGEST_LENGTH];
tr_magnet_info * info = NULL;
if( ( uri != NULL ) && !memcmp( uri, "magnet:?", 8 ) )
{
const char * walk;
for( walk=uri+8; walk && *walk; )
{
const char * key = walk;
const char * delim = strchr( key, '=' );
const char * val = delim == NULL ? NULL : delim + 1;
const char * next = strchr( delim == NULL ? key : val, '&' );
int keylen, vallen;
if( delim != NULL )
keylen = delim - key;
else if( next != NULL )
keylen = next - key;
else
keylen = strlen( key );
if( val == NULL )
vallen = 0;
else if( next != NULL )
vallen = next - val;
else
vallen = strlen( val );
if( ( keylen==2 ) && !memcmp( key, "xt", 2 ) && !memcmp( val, "urn:btih:", 9 ) )
{
const char * hash = val + 9;
const int hashlen = vallen - 9;
if( hashlen == 40 ) {
tr_hex_to_sha1( sha1, hash );
got_checksum = TRUE;
}
else if( hashlen == 32 ) {
base32_to_sha1( sha1, hash, hashlen );
got_checksum = TRUE;
}
}
if( ( keylen==2 ) && !memcmp( key, "dn", 2 ) )
displayName = tr_http_unescape( val, vallen );
if( trCount < MAX_TRACKERS ) {
int i;
if( ( keylen==2 ) && !memcmp( key, "tr", 2 ) )
tr[trCount++] = tr_http_unescape( val, vallen );
else if( ( sscanf( key, "tr.%d=", &i ) == 1 ) && ( i > 0 ) ) /* ticket #3341 */
tr[trCount++] = tr_http_unescape( val, vallen );
}
if( ( keylen==2 ) && !memcmp( key, "ws", 2 ) && ( wsCount < MAX_TRACKERS ) )
ws[wsCount++] = tr_http_unescape( val, vallen );
walk = next != NULL ? next + 1 : NULL;
}
}
if( got_checksum )
{
info = tr_new0( tr_magnet_info, 1 );
info->displayName = displayName;
info->trackerCount = trCount;
info->trackers = tr_memdup( tr, sizeof(char*) * trCount );
info->webseedCount = wsCount;
info->webseeds = tr_memdup( ws, sizeof(char*) * wsCount );
memcpy( info->hash, sha1, sizeof(uint8_t) * SHA_DIGEST_LENGTH );
}
return info;
}
void
tr_magnetFree( tr_magnet_info * info )
{
if( info != NULL )
{
int i;
for( i=0; i<info->trackerCount; ++i )
tr_free( info->trackers[i] );
tr_free( info->trackers );
for( i=0; i<info->webseedCount; ++i )
tr_free( info->webseeds[i] );
tr_free( info->webseeds );
tr_free( info->displayName );
tr_free( info );
}
}
void
tr_magnetCreateMetainfo( const tr_magnet_info * info, tr_benc * top )
{
int i;
tr_benc * d;
tr_bencInitDict( top, 4 );
/* announce list */
if( info->trackerCount == 1 )
tr_bencDictAddStr( top, "announce", info->trackers[0] );
else {
tr_benc * trackers = tr_bencDictAddList( top, "announce-list", info->trackerCount );
for( i=0; i<info->trackerCount; ++i )
tr_bencListAddStr( tr_bencListAddList( trackers, 1 ), info->trackers[i] );
}
/* webseeds */
if( info->webseedCount > 0 ) {
tr_benc * urls = tr_bencDictAddList( top, "url-list", info->webseedCount );
for( i=0; i<info->webseedCount; ++i )
tr_bencListAddStr( urls, info->webseeds[i] );
}
/* nonstandard keys */
d = tr_bencDictAddDict( top, "magnet-info", 2 );
tr_bencDictAddRaw( d, "info_hash", info->hash, 20 );
if( info->displayName != NULL )
tr_bencDictAddStr( d, "display-name", info->displayName );
}