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transmission/libtransmission/metainfo.cc

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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 <algorithm>
#include <array>
#include <cstring> /* strlen() */
#include <string_view>
#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"
using namespace std::literals;
/***
****
***/
#ifdef _WIN32
auto constexpr PATH_DELIMITER_CHARS = std::array<char, 2>{ '/', '\\' };
#else
auto constexpr PATH_DELIMITER_CHARS = std::array<char, 1>{ '/' };
#endif
static constexpr bool char_is_path_separator(char c)
{
for (auto ch : PATH_DELIMITER_CHARS)
{
if (c == ch)
{
return true;
}
}
return false;
}
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 nullptr;
}
}
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;
}
/***
****
***/
char* tr_metainfo_sanitize_path_component(char const* str, size_t len, bool* is_adjusted)
{
if (len == 0 || (len == 1 && str[0] == '.'))
{
return nullptr;
}
*is_adjusted = false;
/* https://docs.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file */
char const* const reserved_chars = "<>:\"/\\|?*";
auto constexpr ReservedNames = std::array<std::string_view, 22>{
"CON"sv, "PRN"sv, "AUX"sv, "NUL"sv, "COM1"sv, "COM2"sv, "COM3"sv, "COM4"sv, "COM5"sv, "COM6"sv, "COM7"sv,
"COM8"sv, "COM9"sv, "LPT1"sv, "LPT2"sv, "LPT3"sv, "LPT4"sv, "LPT5"sv, "LPT6"sv, "LPT7"sv, "LPT8"sv, "LPT9"sv,
};
char* const ret = tr_new(char, len + 2);
memcpy(ret, str, len);
ret[len] = '\0';
for (size_t i = 0; i < len; ++i)
{
if (strchr(reserved_chars, ret[i]) != nullptr || (unsigned char)ret[i] < 0x20)
{
ret[i] = '_';
*is_adjusted = true;
}
}
for (auto const& reserved_name : ReservedNames)
{
size_t const reserved_name_len = std::size(reserved_name);
if (evutil_ascii_strncasecmp(ret, std::data(reserved_name), reserved_name_len) != 0 ||
(ret[reserved_name_len] != '\0' && ret[reserved_name_len] != '.'))
{
continue;
}
memmove(&ret[reserved_name_len + 1], &ret[reserved_name_len], len - reserved_name_len + 1);
ret[reserved_name_len] = '_';
*is_adjusted = true;
++len;
break;
}
size_t start_pos = 0;
size_t end_pos = len;
while (start_pos < len && ret[start_pos] == ' ')
{
++start_pos;
}
while (end_pos > start_pos && (ret[end_pos - 1] == ' ' || ret[end_pos - 1] == '.'))
{
--end_pos;
}
if (start_pos == end_pos)
{
tr_free(ret);
return nullptr;
}
if (start_pos != 0 || end_pos != len)
{
len = end_pos - start_pos;
memmove(ret, &ret[start_pos], len);
ret[len] = '\0';
*is_adjusted = true;
}
return ret;
}
static bool getfile(char** setme, bool* is_adjusted, char const* root, tr_variant* path, struct evbuffer* buf)
{
bool success = false;
size_t root_len = 0;
*setme = nullptr;
*is_adjusted = false;
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 = 0;
char const* str = nullptr;
if (!tr_variantGetStr(tr_variantListChild(path, i), &str, &len))
{
success = false;
break;
}
bool is_component_adjusted = false;
char* final_str = tr_metainfo_sanitize_path_component(str, len, &is_component_adjusted);
if (final_str == nullptr)
{
continue;
}
*is_adjusted = *is_adjusted || is_component_adjusted;
evbuffer_add(buf, TR_PATH_DELIMITER_STR, 1);
evbuffer_add(buf, final_str, strlen(final_str));
tr_free(final_str);
}
}
if (success && evbuffer_get_length(buf) <= root_len)
{
success = false;
}
if (success)
{
char const* const buf_data = (char*)evbuffer_pullup(buf, -1);
size_t const buf_len = evbuffer_get_length(buf);
*setme = tr_utf8clean(std::string_view{ buf_data, buf_len });
if (!*is_adjusted)
{
*is_adjusted = buf_len != strlen(*setme) || strncmp(buf_data, *setme, buf_len) != 0;
}
}
return success;
}
static char const* parseFiles(tr_info* inf, tr_variant* files, tr_variant const* length)
{
int64_t len = 0;
inf->totalSize = 0;
bool is_root_adjusted = false;
char* const root_name = tr_metainfo_sanitize_path_component(inf->name, strlen(inf->name), &is_root_adjusted);
if (root_name == nullptr)
{
return "path";
}
char const* result = nullptr;
if (tr_variantIsList(files)) /* multi-file mode */
{
evbuffer* const buf = evbuffer_new();
result = nullptr;
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++)
{
auto* const file = tr_variantListChild(files, i);
if (!tr_variantIsDict(file))
{
result = "files";
break;
}
tr_variant* path = nullptr;
if (!tr_variantDictFindList(file, TR_KEY_path_utf_8, &path) && !tr_variantDictFindList(file, TR_KEY_path, &path))
{
result = "path";
break;
}
bool is_file_adjusted = false;
if (!getfile(&inf->files[i].name, &is_file_adjusted, root_name, path, buf))
{
result = "path";
break;
}
if (!tr_variantDictFindInt(file, TR_KEY_length, &len))
{
result = "length";
break;
}
inf->files[i].length = len;
inf->files[i].is_renamed = is_root_adjusted || is_file_adjusted;
inf->totalSize += len;
}
evbuffer_free(buf);
}
else if (tr_variantGetInt(length, &len)) /* single-file mode */
{
inf->isFolder = false;
inf->fileCount = 1;
inf->files = tr_new0(tr_file, 1);
inf->files[0].name = tr_strdup(root_name);
inf->files[0].length = len;
inf->files[0].is_renamed = is_root_adjusted;
inf->totalSize += len;
}
else
{
result = "length";
}
tr_free(root_name);
return result;
}
static char* tr_convertAnnounceToScrape(char const* announce)
{
char* scrape = nullptr;
/* 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. */
char const* s = strrchr(announce, '/');
if (s != nullptr && strncmp(s + 1, "announce", 8) == 0)
{
char const* prefix = announce;
size_t const prefix_len = s + 1 - announce;
char const* suffix = s + 1 + 8;
size_t const suffix_len = strlen(suffix);
size_t const alloc_len = prefix_len + 6 + suffix_len + 1;
scrape = tr_new(char, alloc_len);
char* walk = scrape;
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((size_t)(walk - scrape) == 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 = 0;
char const* str = nullptr;
tr_tracker_info* trackers = nullptr;
int trackerCount = 0;
tr_variant* tiers = nullptr;
/* Announce-list */
if (tr_variantDictFindList(meta, TR_KEY_announce_list, &tiers))
{
int const numTiers = tr_variantListSize(tiers);
int n = 0;
for (int i = 0; i < numTiers; i++)
{
n += tr_variantListSize(tr_variantListChild(tiers, i));
}
trackers = tr_new0(tr_tracker_info, n);
int validTiers = 0;
for (int i = 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 = nullptr;
}
}
/* 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++;
}
}
inf->trackers = trackers;
inf->trackerCount = trackerCount;
return nullptr;
}
/**
* @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)
{
char* ret = nullptr;
char* const url = tr_strdup(url_in);
tr_strstrip(url);
size_t const len = strlen(url);
if (tr_urlIsValid(url))
{
if (inf->fileCount > 1 && len > 0 && url[len - 1] != '/')
{
ret = tr_strdup_printf("%*.*s/", TR_ARG_TUPLE((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 = nullptr;
char const* url = nullptr;
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, nullptr))
{
char* fixed_url = fix_webseed_url(inf, url);
if (fixed_url != nullptr)
{
inf->webseeds[inf->webseedCount++] = fixed_url;
}
}
}
}
else if (tr_variantDictFindStr(meta, TR_KEY_url_list, &url, nullptr)) /* handle single items in webseeds */
{
char* fixed_url = fix_webseed_url(inf, url);
if (fixed_url != nullptr)
{
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 = 0;
size_t len = 0;
char const* str = nullptr;
uint8_t const* raw = nullptr;
tr_variant* const meta = const_cast<tr_variant*>(meta_in);
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. */
tr_variant* infoDict = nullptr;
bool b = tr_variantDictFindDict(meta, TR_KEY_info, &infoDict);
if (hasInfoDict != nullptr)
{
*hasInfoDict = b;
}
if (!b)
{
/* no info dictionary... is this a magnet link? */
tr_variant* d = nullptr;
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 == nullptr)
{
inf->name = tr_strdup(inf->hashString);
}
if (inf->originalName == nullptr)
{
inf->originalName = tr_strdup(inf->hashString);
}
}
else /* not a magnet link and has no info dict... */
{
return "info";
}
}
else
{
size_t blen = 0;
char* bstr = tr_variantToStr(infoDict, TR_VARIANT_FMT_BENC, &blen);
tr_sha1(inf->hash, bstr, (int)blen, nullptr);
tr_sha1_to_hex(inf->hashString, inf->hash);
if (infoDictLength != nullptr)
{
*infoDictLength = blen;
}
tr_free(bstr);
}
/* name */
if (!isMagnet)
{
len = 0;
if (!tr_variantDictFindStr(infoDict, TR_KEY_name_utf_8, &str, &len) &&
!tr_variantDictFindStr(infoDict, TR_KEY_name, &str, &len))
{
str = "";
}
if (tr_str_is_empty(str))
{
return "name";
}
tr_free(inf->name);
tr_free(inf->originalName);
inf->name = tr_utf8clean(std::string_view{ str, len });
inf->originalName = tr_strdup(inf->name);
}
/* comment */
len = 0;
if (!tr_variantDictFindStr(meta, TR_KEY_comment_utf_8, &str, &len) &&
!tr_variantDictFindStr(meta, TR_KEY_comment, &str, &len))
{
str = "";
}
tr_free(inf->comment);
inf->comment = tr_utf8clean(std::string_view{ str, len });
/* created by */
len = 0;
if (!tr_variantDictFindStr(meta, TR_KEY_created_by_utf_8, &str, &len) &&
!tr_variantDictFindStr(meta, TR_KEY_created_by, &str, &len))
{
str = "";
}
tr_free(inf->creator);
inf->creator = tr_utf8clean(std::string_view{ 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) && !tr_variantDictFindInt(meta, TR_KEY_private, &i))
{
i = 0;
}
inf->isPrivate = i != 0;
/* source */
len = 0;
if (!tr_variantDictFindStr(infoDict, TR_KEY_source, &str, &len))
{
if (!tr_variantDictFindStr(meta, TR_KEY_source, &str, &len))
{
str = "";
}
}
tr_free(inf->source);
inf->source = tr_utf8clean(std::string_view{ str, len });
/* 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_sha1_digest_t, inf->pieceCount);
std::copy_n(raw, len, (uint8_t*)(inf->pieces));
}
/* files */
if (!isMagnet)
{
if ((str = parseFiles(inf, tr_variantDictFind(infoDict, TR_KEY_files), tr_variantDictFind(infoDict, TR_KEY_length))) !=
nullptr)
{
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)) != nullptr)
{
return str;
}
/* get the url-list */
geturllist(inf, meta);
/* filename of Transmission's copy */
tr_free(inf->torrent);
inf->torrent = session != nullptr ? getTorrentFilename(session, inf, TR_METAINFO_BASENAME_HASH) : nullptr;
return nullptr;
}
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 == nullptr;
if (badTag != nullptr)
{
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->source);
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 = getTorrentFilename(session, inf, TR_METAINFO_BASENAME_HASH);
tr_sys_path_remove(filename, nullptr);
tr_free(filename);
filename = getTorrentFilename(session, inf, TR_METAINFO_BASENAME_NAME_AND_PARTIAL_HASH);
tr_sys_path_remove(filename, nullptr);
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, nullptr))
{
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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