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transmission/libtransmission/metainfo.c
Mike Gelfand bb4741002f Go back to using hash as base name for resume and torrent files 
The format introduced in TRAC-394 is nice but brings its own issues (e.g.
TRAC-4189, #122). I'm okay with a bit of grepping myself if it makes the
experience better for end users.

Using hashes results in filenames well under 255 bytes limit on some
filesystems. If even that will not be enough, I'd suggest reporting the
issue elsewhere.

Fixes: #122
2017-07-26 21:32:26 +03:00

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/*
* This file Copyright (C) 2007-2014 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <string.h> /* strlen() */
#include <event2/buffer.h>
#include "transmission.h"
#include "crypto-utils.h" /* tr_sha1 */
#include "file.h"
#include "log.h"
#include "metainfo.h"
#include "platform.h" /* tr_getTorrentDir() */
#include "session.h"
#include "tr-assert.h"
#include "utils.h"
#include "variant.h"
/***
****
***/
#ifdef _WIN32
#define PATH_DELIMITER_CHARS "/\\"
#else
#define PATH_DELIMITER_CHARS "/"
#endif
static inline bool char_is_path_separator(char c)
{
return strchr(PATH_DELIMITER_CHARS, c) != NULL;
}
static char* metainfoGetBasenameNameAndPartialHash(tr_info const* inf)
{
char const* name = inf->originalName;
size_t const name_len = strlen(name);
char* ret = tr_strdup_printf("%s.%16.16s", name, inf->hashString);
for (size_t i = 0; i < name_len; ++i)
{
if (char_is_path_separator(ret[i]))
{
ret[i] = '_';
}
}
return ret;
}
static char* metainfoGetBasenameHashOnly(tr_info const* inf)
{
return tr_strdup(inf->hashString);
}
char* tr_metainfoGetBasename(tr_info const* inf, enum tr_metainfo_basename_format format)
{
switch (format)
{
case TR_METAINFO_BASENAME_NAME_AND_PARTIAL_HASH:
return metainfoGetBasenameNameAndPartialHash(inf);
case TR_METAINFO_BASENAME_HASH:
return metainfoGetBasenameHashOnly(inf);
default:
TR_ASSERT_MSG(false, "unknown metainfo basename format %d", (int)format);
return NULL;
}
}
static char* getTorrentFilename(tr_session const* session, tr_info const* inf, enum tr_metainfo_basename_format format)
{
char* base = tr_metainfoGetBasename(inf, format);
char* filename = tr_strdup_printf("%s" TR_PATH_DELIMITER_STR "%s.torrent", tr_getTorrentDir(session), base);
tr_free(base);
return filename;
}
/***
****
***/
static bool path_component_is_suspicious(char const* component)
{
return component == NULL || strpbrk(component, PATH_DELIMITER_CHARS) != NULL || strcmp(component, ".") == 0 ||
strcmp(component, "..") == 0;
}
static bool getfile(char** setme, char const* root, tr_variant* path, struct evbuffer* buf)
{
/* root's already been checked by caller */
TR_ASSERT(!path_component_is_suspicious(root));
bool success = false;
size_t root_len = 0;
*setme = NULL;
if (tr_variantIsList(path))
{
success = true;
evbuffer_drain(buf, evbuffer_get_length(buf));
root_len = strlen(root);
evbuffer_add(buf, root, root_len);
for (int i = 0, n = tr_variantListSize(path); i < n; i++)
{
size_t len;
char const* str;
if (!tr_variantGetStr(tr_variantListChild(path, i), &str, &len) || path_component_is_suspicious(str))
{
success = false;
break;
}
if (*str == '\0')
{
continue;
}
evbuffer_add(buf, TR_PATH_DELIMITER_STR, 1);
evbuffer_add(buf, str, len);
}
}
if (success && evbuffer_get_length(buf) <= root_len)
{
success = false;
}
if (success)
{
*setme = tr_utf8clean((char*)evbuffer_pullup(buf, -1), evbuffer_get_length(buf));
/* fprintf(stderr, "[%s]\n", *setme); */
}
return success;
}
static char const* parseFiles(tr_info* inf, tr_variant* files, tr_variant const* length)
{
int64_t len;
inf->totalSize = 0;
if (tr_variantIsList(files)) /* multi-file mode */
{
struct evbuffer* buf;
char const* result;
if (path_component_is_suspicious(inf->name))
{
return "path";
}
buf = evbuffer_new();
result = NULL;
inf->isFolder = true;
inf->fileCount = tr_variantListSize(files);
inf->files = tr_new0(tr_file, inf->fileCount);
for (tr_file_index_t i = 0; i < inf->fileCount; i++)
{
tr_variant* file;
tr_variant* path;
file = tr_variantListChild(files, i);
if (!tr_variantIsDict(file))
{
result = "files";
break;
}
if (!tr_variantDictFindList(file, TR_KEY_path_utf_8, &path))
{
if (!tr_variantDictFindList(file, TR_KEY_path, &path))
{
result = "path";
break;
}
}
if (!getfile(&inf->files[i].name, inf->name, path, buf))
{
result = "path";
break;
}
if (!tr_variantDictFindInt(file, TR_KEY_length, &len))
{
result = "length";
break;
}
inf->files[i].length = len;
inf->totalSize += len;
}
evbuffer_free(buf);
return result;
}
else if (tr_variantGetInt(length, &len)) /* single-file mode */
{
if (path_component_is_suspicious(inf->name))
{
return "path";
}
inf->isFolder = false;
inf->fileCount = 1;
inf->files = tr_new0(tr_file, 1);
inf->files[0].name = tr_strdup(inf->name);
inf->files[0].length = len;
inf->totalSize += len;
}
else
{
return "length";
}
return NULL;
}
static char* tr_convertAnnounceToScrape(char const* announce)
{
char* scrape = NULL;
char const* s;
/* To derive the scrape URL use the following steps:
* Begin with the announce URL. Find the last '/' in it.
* If the text immediately following that '/' isn't 'announce'
* it will be taken as a sign that that tracker doesn't support
* the scrape convention. If it does, substitute 'scrape' for
* 'announce' to find the scrape page. */
if ((s = strrchr(announce, '/')) != NULL && strncmp(++s, "announce", 8) == 0)
{
char const* prefix = announce;
size_t const prefix_len = s - announce;
char const* suffix = s + 8;
size_t const suffix_len = strlen(suffix);
size_t const alloc_len = prefix_len + 6 + suffix_len + 1;
char* walk = scrape = tr_new(char, alloc_len);
memcpy(walk, prefix, prefix_len);
walk += prefix_len;
memcpy(walk, "scrape", 6);
walk += 6;
memcpy(walk, suffix, suffix_len);
walk += suffix_len;
*walk++ = '\0';
TR_ASSERT(walk - scrape == (int)alloc_len);
}
/* Some torrents with UDP announce URLs don't have /announce. */
else if (strncmp(announce, "udp:", 4) == 0)
{
scrape = tr_strdup(announce);
}
return scrape;
}
static char const* getannounce(tr_info* inf, tr_variant* meta)
{
size_t len;
char const* str;
tr_tracker_info* trackers = NULL;
int trackerCount = 0;
tr_variant* tiers;
/* Announce-list */
if (tr_variantDictFindList(meta, TR_KEY_announce_list, &tiers))
{
int n;
int const numTiers = tr_variantListSize(tiers);
n = 0;
for (int i = 0; i < numTiers; i++)
{
n += tr_variantListSize(tr_variantListChild(tiers, i));
}
trackers = tr_new0(tr_tracker_info, n);
for (int i = 0, validTiers = 0; i < numTiers; i++)
{
tr_variant* tier = tr_variantListChild(tiers, i);
int const tierSize = tr_variantListSize(tier);
bool anyAdded = false;
for (int j = 0; j < tierSize; j++)
{
if (tr_variantGetStr(tr_variantListChild(tier, j), &str, &len))
{
char* url = tr_strstrip(tr_strndup(str, len));
if (!tr_urlIsValidTracker(url))
{
tr_free(url);
}
else
{
tr_tracker_info* t = trackers + trackerCount;
t->tier = validTiers;
t->announce = url;
t->scrape = tr_convertAnnounceToScrape(url);
t->id = trackerCount;
anyAdded = true;
++trackerCount;
}
}
}
if (anyAdded)
{
++validTiers;
}
}
/* did we use any of the tiers? */
if (trackerCount == 0)
{
tr_free(trackers);
trackers = NULL;
}
}
/* Regular announce value */
if (trackerCount == 0 && tr_variantDictFindStr(meta, TR_KEY_announce, &str, &len))
{
char* url = tr_strstrip(tr_strndup(str, len));
if (!tr_urlIsValidTracker(url))
{
tr_free(url);
}
else
{
trackers = tr_new0(tr_tracker_info, 1);
trackers[trackerCount].tier = 0;
trackers[trackerCount].announce = url;
trackers[trackerCount].scrape = tr_convertAnnounceToScrape(url);
trackers[trackerCount].id = 0;
trackerCount++;
/* fprintf(stderr, "single announce: [%s]\n", url); */
}
}
inf->trackers = trackers;
inf->trackerCount = trackerCount;
return NULL;
}
/**
* @brief Ensure that the URLs for multfile torrents end in a slash.
*
* See http://bittorrent.org/beps/bep_0019.html#metadata-extension
* for background on how the trailing slash is used for "url-list"
* fields.
*
* This function is to workaround some .torrent generators, such as
* mktorrent and very old versions of utorrent, that don't add the
* trailing slash for multifile torrents if omitted by the end user.
*/
static char* fix_webseed_url(tr_info const* inf, char const* url_in)
{
size_t len;
char* url;
char* ret = NULL;
url = tr_strdup(url_in);
tr_strstrip(url);
len = strlen(url);
if (tr_urlIsValid(url, len))
{
if (inf->fileCount > 1 && len > 0 && url[len - 1] != '/')
{
ret = tr_strdup_printf("%*.*s/", (int)len, (int)len, url);
}
else
{
ret = tr_strndup(url, len);
}
}
tr_free(url);
return ret;
}
static void geturllist(tr_info* inf, tr_variant* meta)
{
tr_variant* urls;
char const* url;
if (tr_variantDictFindList(meta, TR_KEY_url_list, &urls))
{
int const n = tr_variantListSize(urls);
inf->webseedCount = 0;
inf->webseeds = tr_new0(char*, n);
for (int i = 0; i < n; i++)
{
if (tr_variantGetStr(tr_variantListChild(urls, i), &url, NULL))
{
char* fixed_url = fix_webseed_url(inf, url);
if (fixed_url != NULL)
{
inf->webseeds[inf->webseedCount++] = fixed_url;
}
}
}
}
else if (tr_variantDictFindStr(meta, TR_KEY_url_list, &url, NULL)) /* handle single items in webseeds */
{
char* fixed_url = fix_webseed_url(inf, url);
if (fixed_url != NULL)
{
inf->webseedCount = 1;
inf->webseeds = tr_new0(char*, 1);
inf->webseeds[0] = fixed_url;
}
}
}
static char const* tr_metainfoParseImpl(tr_session const* session, tr_info* inf, bool* hasInfoDict, size_t* infoDictLength,
tr_variant const* meta_in)
{
int64_t i;
size_t len;
char const* str;
uint8_t const* raw;
tr_variant* d;
tr_variant* infoDict = NULL;
tr_variant* meta = (tr_variant*)meta_in;
bool b;
bool isMagnet = false;
/* info_hash: urlencoded 20-byte SHA1 hash of the value of the info key
* from the Metainfo file. Note that the value will be a bencoded
* dictionary, given the definition of the info key above. */
b = tr_variantDictFindDict(meta, TR_KEY_info, &infoDict);
if (hasInfoDict != NULL)
{
*hasInfoDict = b;
}
if (!b)
{
/* no info dictionary... is this a magnet link? */
if (tr_variantDictFindDict(meta, TR_KEY_magnet_info, &d))
{
isMagnet = true;
/* get the info-hash */
if (!tr_variantDictFindRaw(d, TR_KEY_info_hash, &raw, &len))
{
return "info_hash";
}
if (len != SHA_DIGEST_LENGTH)
{
return "info_hash";
}
memcpy(inf->hash, raw, len);
tr_sha1_to_hex(inf->hashString, inf->hash);
/* maybe get the display name */
if (tr_variantDictFindStr(d, TR_KEY_display_name, &str, &len))
{
tr_free(inf->name);
tr_free(inf->originalName);
inf->name = tr_strndup(str, len);
inf->originalName = tr_strndup(str, len);
}
if (inf->name == NULL)
{
inf->name = tr_strdup(inf->hashString);
}
if (inf->originalName == NULL)
{
inf->originalName = tr_strdup(inf->hashString);
}
}
else /* not a magnet link and has no info dict... */
{
return "info";
}
}
else
{
size_t len;
char* bstr = tr_variantToStr(infoDict, TR_VARIANT_FMT_BENC, &len);
tr_sha1(inf->hash, bstr, (int)len, NULL);
tr_sha1_to_hex(inf->hashString, inf->hash);
if (infoDictLength != NULL)
{
*infoDictLength = len;
}
tr_free(bstr);
}
/* name */
if (!isMagnet)
{
len = 0;
if (!tr_variantDictFindStr(infoDict, TR_KEY_name_utf_8, &str, &len))
{
if (!tr_variantDictFindStr(infoDict, TR_KEY_name, &str, &len))
{
str = "";
}
}
if (str == NULL || *str == '\0')
{
return "name";
}
tr_free(inf->name);
tr_free(inf->originalName);
inf->name = tr_utf8clean(str, len);
inf->originalName = tr_strdup(inf->name);
}
/* comment */
len = 0;
if (!tr_variantDictFindStr(meta, TR_KEY_comment_utf_8, &str, &len))
{
if (!tr_variantDictFindStr(meta, TR_KEY_comment, &str, &len))
{
str = "";
}
}
tr_free(inf->comment);
inf->comment = tr_utf8clean(str, len);
/* created by */
len = 0;
if (!tr_variantDictFindStr(meta, TR_KEY_created_by_utf_8, &str, &len))
{
if (!tr_variantDictFindStr(meta, TR_KEY_created_by, &str, &len))
{
str = "";
}
}
tr_free(inf->creator);
inf->creator = tr_utf8clean(str, len);
/* creation date */
if (!tr_variantDictFindInt(meta, TR_KEY_creation_date, &i))
{
i = 0;
}
inf->dateCreated = i;
/* private */
if (!tr_variantDictFindInt(infoDict, TR_KEY_private, &i))
{
if (!tr_variantDictFindInt(meta, TR_KEY_private, &i))
{
i = 0;
}
}
inf->isPrivate = i != 0;
/* piece length */
if (!isMagnet)
{
if (!tr_variantDictFindInt(infoDict, TR_KEY_piece_length, &i) || (i < 1))
{
return "piece length";
}
inf->pieceSize = i;
}
/* pieces */
if (!isMagnet)
{
if (!tr_variantDictFindRaw(infoDict, TR_KEY_pieces, &raw, &len))
{
return "pieces";
}
if (len % SHA_DIGEST_LENGTH != 0)
{
return "pieces";
}
inf->pieceCount = len / SHA_DIGEST_LENGTH;
inf->pieces = tr_new0(tr_piece, inf->pieceCount);
for (tr_piece_index_t i = 0; i < inf->pieceCount; i++)
{
memcpy(inf->pieces[i].hash, &raw[i * SHA_DIGEST_LENGTH], SHA_DIGEST_LENGTH);
}
}
/* files */
if (!isMagnet)
{
if ((str = parseFiles(inf, tr_variantDictFind(infoDict, TR_KEY_files), tr_variantDictFind(infoDict, TR_KEY_length))) != NULL)
{
return str;
}
if (inf->fileCount == 0 || inf->totalSize == 0)
{
return "files";
}
if ((uint64_t)inf->pieceCount != (inf->totalSize + inf->pieceSize - 1) / inf->pieceSize)
{
return "files";
}
}
/* get announce or announce-list */
if ((str = getannounce(inf, meta)) != NULL)
{
return str;
}
/* get the url-list */
geturllist(inf, meta);
/* filename of Transmission's copy */
tr_free(inf->torrent);
inf->torrent = session != NULL ? getTorrentFilename(session, inf, TR_METAINFO_BASENAME_HASH) : NULL;
return NULL;
}
bool tr_metainfoParse(tr_session const* session, tr_variant const* meta_in, tr_info* inf, bool* hasInfoDict,
size_t* infoDictLength)
{
char const* badTag = tr_metainfoParseImpl(session, inf, hasInfoDict, infoDictLength, meta_in);
bool const success = badTag == NULL;
if (badTag != NULL)
{
tr_logAddNamedError(inf->name, _("Invalid metadata entry \"%s\""), badTag);
tr_metainfoFree(inf);
}
return success;
}
void tr_metainfoFree(tr_info* inf)
{
for (unsigned int i = 0; i < inf->webseedCount; i++)
{
tr_free(inf->webseeds[i]);
}
for (tr_file_index_t ff = 0; ff < inf->fileCount; ff++)
{
tr_free(inf->files[ff].name);
}
tr_free(inf->webseeds);
tr_free(inf->pieces);
tr_free(inf->files);
tr_free(inf->comment);
tr_free(inf->creator);
tr_free(inf->torrent);
tr_free(inf->originalName);
tr_free(inf->name);
for (unsigned int i = 0; i < inf->trackerCount; i++)
{
tr_free(inf->trackers[i].announce);
tr_free(inf->trackers[i].scrape);
}
tr_free(inf->trackers);
memset(inf, '\0', sizeof(tr_info));
}
void tr_metainfoRemoveSaved(tr_session const* session, tr_info const* inf)
{
char* filename;
filename = getTorrentFilename(session, inf, TR_METAINFO_BASENAME_HASH);
tr_sys_path_remove(filename, NULL);
tr_free(filename);
filename = getTorrentFilename(session, inf, TR_METAINFO_BASENAME_NAME_AND_PARTIAL_HASH);
tr_sys_path_remove(filename, NULL);
tr_free(filename);
}
void tr_metainfoMigrateFile(tr_session const* session, tr_info const* info, enum tr_metainfo_basename_format old_format,
enum tr_metainfo_basename_format new_format)
{
char* old_filename = getTorrentFilename(session, info, old_format);
char* new_filename = getTorrentFilename(session, info, new_format);
if (tr_sys_path_rename(old_filename, new_filename, NULL))
{
tr_logAddNamedError(info->name, "Migrated torrent file from \"%s\" to \"%s\"", old_filename, new_filename);
}
tr_free(new_filename);
tr_free(old_filename);
}
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