transmission/libtransmission/magnet.c

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/*
* This file Copyright (C) 2009 Charles Kerr <charles@transmissionbt.com>
*
* 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 <ctype.h> /* tolower() */
#include <string.h> /* strchr() */
#include "transmission.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[] =
{
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
tr_magnet_info *
tr_magnetParse( const char * uri )
{
tr_bool got_checksum = FALSE;
int announceCount = 0;
char * announceURLs[MAX_TRACKERS];
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( ( keylen==2 ) && !memcmp( key, "tr", 2 ) )
announceURLs[announceCount++] = 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->announceCount = announceCount;
info->announceURLs = tr_memdup( announceURLs, sizeof(char*) * announceCount );
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->announceCount; ++i )
tr_free( info->announceURLs[i] );
tr_free( info->announceURLs );
tr_free( info->displayName );
tr_free( info );
}
}