transmission/libtransmission/magnet-metainfo.cc

276 lines
7.6 KiB
C++

// This file Copyright © 2010-2023 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <array>
#include <cstdint> // uint8_t
#include <cstring>
#include <iterator> // back_inserter
#include <optional>
#include <string_view>
#include <fmt/core.h>
#include "libtransmission/crypto-utils.h"
#include "libtransmission/error.h"
#include "libtransmission/error-types.h"
#include "libtransmission/magnet-metainfo.h"
#include "libtransmission/tr-strbuf.h" // for tr_urlbuf
#include "libtransmission/utils.h"
#include "libtransmission/web-utils.h"
using namespace std::literals;
namespace
{
auto constexpr Base32HashStrLen = size_t{ 32 };
/* this base32 code converted from code by Robert Kaye and Gordon Mohr
* and is public domain. see http://bitzi.com/publicdomain for more info */
namespace bitzi
{
auto constexpr Base32Lookup = std::array<int, 80>{
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' */
};
void base32_to_sha1(uint8_t* out, char const* in, size_t const inlen)
{
size_t const outlen = 20;
memset(out, 0, 20);
size_t index = 0;
size_t offset = 0;
for (size_t i = 0; i < inlen; ++i)
{
int const lookup = in[i] - '0';
/* Skip chars outside the lookup table */
if (lookup < 0)
{
continue;
}
/* If this digit is not in the table, ignore it */
int const 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);
}
}
}
} // namespace bitzi
std::optional<tr_sha1_digest_t> parseBase32Hash(std::string_view sv)
{
if (std::size(sv) != Base32HashStrLen)
{
return {};
}
if (!std::all_of(
std::begin(sv),
std::end(sv),
[](unsigned char ch)
{ return '0' <= ch && ch < '0' + std::size(bitzi::Base32Lookup) && bitzi::Base32Lookup[ch - '0'] != 0xFF; }))
{
return {};
}
auto digest = tr_sha1_digest_t{};
bitzi::base32_to_sha1(reinterpret_cast<uint8_t*>(std::data(digest)), std::data(sv), std::size(sv));
return digest;
}
std::optional<tr_sha1_digest_t> parseHash(std::string_view sv)
{
// http://bittorrent.org/beps/bep_0009.html
// Is the info-hash hex encoded, for a total of 40 characters.
// For compatibility with existing links in the wild, clients
// should also support the 32 character base32 encoded info-hash.
if (auto const hash = tr_sha1_from_string(sv); hash)
{
return hash;
}
if (auto const hash = parseBase32Hash(sv); hash)
{
return hash;
}
return {};
}
std::optional<tr_sha256_digest_t> parseHash2(std::string_view sv)
{
// http://bittorrent.org/beps/bep_0009.html
// Is the info-hash v2 hex encoded and tag removed, for a total of 64 characters.
if (auto const hash = tr_sha256_from_string(sv); hash)
{
return hash;
}
return {};
}
} // namespace
// ---
std::string tr_magnet_metainfo::magnet() const
{
auto buf = tr_urlbuf{ "magnet:?xt=urn:btih:"sv, info_hash_string() };
if (!std::empty(name_))
{
buf += "&dn="sv;
tr_urlPercentEncode(std::back_inserter(buf), name_);
}
for (auto const& tracker : this->announce_list())
{
buf += "&tr="sv;
tr_urlPercentEncode(std::back_inserter(buf), tracker.announce.sv());
}
for (auto const& webseed : webseed_urls_)
{
buf += "&ws="sv;
tr_urlPercentEncode(std::back_inserter(buf), webseed);
}
return std::string{ buf.sv() };
}
void tr_magnet_metainfo::add_webseed(std::string_view webseed)
{
if (!tr_urlIsValid(webseed))
{
return;
}
auto& urls = webseed_urls_;
if (auto const it = std::find(std::begin(urls), std::end(urls), webseed); it != std::end(urls))
{
return;
}
urls.emplace_back(webseed);
}
bool tr_magnet_metainfo::parseMagnet(std::string_view magnet_link, tr_error** error)
{
magnet_link = tr_strv_strip(magnet_link);
if (auto const hash = parseHash(magnet_link); hash)
{
return parseMagnet(fmt::format(FMT_STRING("magnet:?xt=urn:btih:{:s}"), tr_sha1_to_string(*hash)));
}
auto const parsed = tr_urlParse(magnet_link);
if (!parsed || parsed->scheme != "magnet"sv)
{
tr_error_set(error, TR_ERROR_EINVAL, "Error parsing URL"sv);
return false;
}
bool got_hash = false;
for (auto const& [key, value] : tr_url_query_view{ parsed->query })
{
if (key == "dn"sv)
{
this->set_name(tr_urlPercentDecode(value));
}
else if (key == "tr"sv || tr_strv_starts_with(key, "tr."sv))
{
// "tr." explanation @ https://trac.transmissionbt.com/ticket/3341
this->announce_list_.add(tr_urlPercentDecode(value));
}
else if (key == "ws"sv)
{
auto const url = tr_urlPercentDecode(value);
auto const url_sv = tr_strv_strip(url);
if (tr_urlIsValid(url_sv))
{
this->webseed_urls_.emplace_back(url_sv);
}
}
else if (static auto constexpr ValPrefix = "urn:btih:"sv; key == "xt"sv && tr_strv_starts_with(value, ValPrefix))
{
// v1 info-hash
if (auto const hash = parseHash(value.substr(std::size(ValPrefix))); hash)
{
this->info_hash_ = *hash;
got_hash = true;
}
}
else if (static auto constexpr ValPrefix2 = "urn:btmh:1220"sv; key == "xt"sv && tr_strv_starts_with(value, ValPrefix2))
{
// v2 info-hash
// The 1220 tag identifies the hash as sha256, removing tag before sending to parseHash2
if (auto const hash = parseHash2(value.substr(std::size(ValPrefix2))); hash)
{
this->info_hash2_ = *hash;
}
}
}
info_hash_str_ = tr_sha1_to_string(this->info_hash());
if (std::empty(name()))
{
this->set_name(info_hash_str_);
}
return got_hash;
}