transmission/libtransmission/magnet.c

248 lines
6.8 KiB
C

/*
* 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 <string.h> /* strchr () */
#include <stdio.h> /* sscanf () */
#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[] =
{
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)
{
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) && val && !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 ((vallen > 0) && (keylen==2) && !memcmp (key, "dn", 2))
displayName = tr_http_unescape (val, vallen);
if ((vallen > 0) && (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 and #5134 */
tr[trCount++] = tr_http_unescape (val, vallen);
}
if ((vallen > 0) && (keylen==2) && !memcmp (key, "ws", 2) && (wsCount < MAX_WEBSEEDS))
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);
}