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transmission/libtransmission/torrent-magnet.c
Mike Gelfand 4cfe7e7ddb #4400, #5462: Move SHA1 helpers to crypto-utils 
On a way to factoring out OpenSSL support to a standalone file to ease
addition of other crypto libraries support in the future, move helpers
providing SHA1 calculation to crypto-utils.{c,h}. OpenSSL-related
functionality (SHA1 context management) is moved to crypto-utils-openssl.c.

Add new tr_sha1_ctx_t type and functions to be implemented by crypto
backends:
* tr_sha1_init - allocate SHA1 context and and initialize it,
* tr_sha1_update - hash some [more] data,
* tr_sha1_final - finish hash calculation and free the context.

Add new files to CMakeLists.txt (leftover from previous commit) to fix
CMake-based configuration.
2014-12-04 12:13:59 +00:00

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/*
* This file Copyright (C) 2012-2014 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
* $Id$
*/
#include <assert.h>
#include <string.h> /* memcpy (), memset (), memcmp () */
#include <event2/buffer.h>
#include "transmission.h"
#include "crypto-utils.h" /* tr_sha1 () */
#include "file.h"
#include "log.h"
#include "magnet.h"
#include "metainfo.h"
#include "resume.h"
#include "torrent.h"
#include "torrent-magnet.h"
#include "utils.h"
#include "variant.h"
#include "web.h"
#define dbgmsg(tor, ...) \
do \
{ \
if (tr_logGetDeepEnabled ()) \
tr_logAddDeep (__FILE__, __LINE__, tr_torrentName (tor), __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_variant top;
if (!tr_variantFromBenc (&top, fileContents, fileLen))
{
tr_variant * infoDict;
if (tr_variantDictFindDict (&top, TR_KEY_info, &infoDict))
{
int infoLen;
char * infoContents = tr_variantToStr (infoDict, TR_VARIANT_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_variantFree (&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))
{
tr_sys_file_t fd;
ensureInfoDictOffsetIsCached (tor);
assert (tor->infoDictLength > 0);
assert (tor->infoDictOffset >= 0);
fd = tr_sys_file_open (tor->info.torrent, TR_SYS_FILE_READ, 0, NULL);
if (fd != TR_BAD_SYS_FILE)
{
const int o = piece * METADATA_PIECE_SIZE;
if (tr_sys_file_seek (fd, tor->infoDictOffset + o, TR_SEEK_SET, NULL, NULL))
{
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);
uint64_t n;
if (tr_sys_file_read (fd, buf, l, &n, NULL) && n == (unsigned int) l)
{
*len = l;
ret = buf;
buf = NULL;
}
tr_free (buf);
}
}
tr_sys_file_close (fd, NULL);
}
}
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_variant infoDict;
const int err = tr_variantFromBenc (&infoDict, m->metadata, m->metadata_size);
dbgmsg (tor, "err is %d", err);
if ((metainfoParsed = !err))
{
/* yay we have bencoded metainfo... merge it into our .torrent file */
tr_variant newMetainfo;
char * path = tr_strdup (tor->info.torrent);
if (!tr_variantFromFile (&newMetainfo, TR_VARIANT_FMT_BENC, path))
{
bool hasInfo;
tr_info info;
int infoDictLength;
/* remove any old .torrent and .resume files */
tr_sys_path_remove (path, NULL);
tr_torrentRemoveResume (tor);
dbgmsg (tor, "Saving completed metadata to \"%s\"", path);
tr_variantMergeDicts (tr_variantDictAddDict (&newMetainfo, TR_KEY_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_variantToFile (&newMetainfo, TR_VARIANT_FMT_BENC, tor->info.torrent);
tr_sessionSetTorrentFile (tor->session, tor->info.hashString, tor->info.torrent);
tr_torrentGotNewInfoDict (tor);
tr_torrentSetDirty (tor);
}
tr_variantFree (&newMetainfo);
}
tr_variantFree (&infoDict);
tr_free (path);
}
}
if (success)
{
incompleteMetadataFree (tor->incompleteMetadata);
tor->incompleteMetadata = NULL;
tor->isStopping = true;
tor->magnetVerify = true;
tor->startAfterVerify = true;
}
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_logAddError ("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;
}
/* FIXME: this should be renamed tr_metainfoGetMagnetLink() and moved to metainfo.c for consistency */
char *
tr_torrentInfoGetMagnetLink (const tr_info * inf)
{
unsigned int i;
const char * name;
struct evbuffer * s = evbuffer_new ();
evbuffer_add_printf (s, "magnet:?xt=urn:btih:%s", inf->hashString);
name = inf->name;
if (name && *name)
{
evbuffer_add_printf (s, "%s", "&dn=");
tr_http_escape (s, name, -1, true);
}
for (i=0; i<inf->trackerCount; ++i)
{
evbuffer_add_printf (s, "%s", "&tr=");
tr_http_escape (s, inf->trackers[i].announce, -1, true);
}
for (i=0; i<inf->webseedCount; i++)
{
evbuffer_add_printf (s, "%s", "&ws=");
tr_http_escape (s, inf->webseeds[i], -1, true);
}
return evbuffer_free_to_str (s);
}
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