268 lines
7.0 KiB
C++
268 lines
7.0 KiB
C++
// This file Copyright © 2007-2023 Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#include <algorithm>
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#include <array>
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#include <cctype>
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#include <iterator>
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#include <random>
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#include <string>
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#include <string_view>
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#include <type_traits>
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#include <vector>
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extern "C"
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{
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#include <b64/cdecode.h>
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#include <b64/cencode.h>
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}
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#include <fmt/core.h>
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#include "libtransmission/transmission.h"
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#include "libtransmission/crypto-utils.h"
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#include "libtransmission/tr-assert.h"
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#include "libtransmission/utils.h"
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using namespace std::literals;
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// ---
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namespace
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{
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constexpr auto TrSha1DigestStrlen = size_t{ 40 };
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constexpr auto TrSha256DigestStrlen = size_t{ 64 };
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namespace ssha1_impl
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{
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auto constexpr DigestStringSize = TrSha1DigestStrlen;
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auto constexpr SaltedPrefix = "{"sv;
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std::string tr_salt(std::string_view plaintext, std::string_view salt)
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{
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static_assert(DigestStringSize == 40);
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// build a sha1 digest of the original content and the salt
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auto const digest = tr_sha1::digest(plaintext, salt);
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// convert it to a string. string holds three parts:
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// DigestPrefix, stringified digest of plaintext + salt, and the salt.
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return fmt::format(FMT_STRING("{:s}{:s}{:s}"), SaltedPrefix, tr_sha1_to_string(digest), salt);
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}
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} // namespace ssha1_impl
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} // namespace
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std::string tr_ssha1(std::string_view plaintext)
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{
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using namespace ssha1_impl;
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// build an array of random Salter chars
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auto constexpr Salter = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ./"sv;
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static_assert(std::size(Salter) == 64);
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auto constexpr SaltSize = size_t{ 8 };
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auto salt = tr_rand_obj<std::array<char, SaltSize>>();
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std::transform(
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std::begin(salt),
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std::end(salt),
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std::begin(salt),
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[&Salter](auto ch) { return Salter[ch % std::size(Salter)]; });
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return tr_salt(plaintext, std::string_view{ std::data(salt), std::size(salt) });
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}
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bool tr_ssha1_test(std::string_view text)
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{
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using namespace ssha1_impl;
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return tr_strv_starts_with(text, SaltedPrefix) && std::size(text) >= std::size(SaltedPrefix) + DigestStringSize;
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}
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bool tr_ssha1_matches(std::string_view ssha1, std::string_view plaintext)
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{
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using namespace ssha1_impl;
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if (!tr_ssha1_test(ssha1))
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{
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return false;
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}
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auto const salt = ssha1.substr(std::size(SaltedPrefix) + DigestStringSize);
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return tr_salt(plaintext, salt) == ssha1;
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}
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// ---
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namespace
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{
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namespace base64_impl
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{
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constexpr size_t base64AllocSize(std::string_view input)
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{
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size_t ret_length = 4 * ((std::size(input) + 2) / 3); // NOLINT misc-const-correctness
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#ifdef USE_SYSTEM_B64
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// Additional space is needed for newlines if we're using unpatched libb64
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ret_length += ret_length / 72 + 1;
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#endif
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return ret_length * 8;
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}
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} // namespace base64_impl
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} // namespace
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std::string tr_base64_encode(std::string_view input)
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{
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using namespace base64_impl;
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auto buf = std::vector<char>(base64AllocSize(input));
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auto state = base64_encodestate{};
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base64_init_encodestate(&state);
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size_t len = base64_encode_block(std::data(input), std::size(input), std::data(buf), &state);
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len += base64_encode_blockend(std::data(buf) + len, &state);
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auto str = std::string{};
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std::copy_if(
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std::data(buf),
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std::data(buf) + len,
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std::back_inserter(str),
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[](auto ch) { return !tr_strv_contains("\r\n"sv, ch); });
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return str;
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}
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std::string tr_base64_decode(std::string_view input)
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{
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auto buf = std::vector<char>(std::size(input) + 8);
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auto state = base64_decodestate{};
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base64_init_decodestate(&state);
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size_t const len = base64_decode_block(std::data(input), std::size(input), std::data(buf), &state);
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return std::string{ std::data(buf), len };
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}
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// ---
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namespace
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{
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namespace hex_impl
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{
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constexpr void tr_binary_to_hex(void const* vinput, void* voutput, size_t byte_length)
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{
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auto constexpr Hex = "0123456789abcdef"sv;
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auto const* input = static_cast<uint8_t const*>(vinput);
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auto* output = static_cast<char*>(voutput);
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/* go from back to front to allow for in-place conversion */
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input += byte_length;
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output += byte_length * 2;
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*output = '\0';
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while (byte_length-- > 0)
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{
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unsigned int const val = *(--input);
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*(--output) = Hex[val & 0xf];
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*(--output) = Hex[val >> 4];
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}
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}
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constexpr void tr_hex_to_binary(char const* input, void* voutput, size_t byte_length)
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{
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auto constexpr Hex = "0123456789abcdef"sv;
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auto* output = static_cast<uint8_t*>(voutput);
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for (size_t i = 0; i < byte_length; ++i)
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{
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auto const upper_nibble = Hex.find(std::tolower(*input++));
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auto const lower_nibble = Hex.find(std::tolower(*input++));
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*output++ = (uint8_t)((upper_nibble << 4) | lower_nibble);
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}
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}
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} // namespace hex_impl
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} // namespace
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std::string tr_sha1_to_string(tr_sha1_digest_t const& digest)
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{
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using namespace hex_impl;
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auto str = std::string(std::size(digest) * 2, '?');
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tr_binary_to_hex(digest.data(), str.data(), std::size(digest));
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return str;
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}
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std::string tr_sha256_to_string(tr_sha256_digest_t const& digest)
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{
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using namespace hex_impl;
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auto str = std::string(std::size(digest) * 2, '?');
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tr_binary_to_hex(digest.data(), str.data(), std::size(digest));
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return str;
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}
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std::optional<tr_sha1_digest_t> tr_sha1_from_string(std::string_view hex)
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{
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using namespace hex_impl;
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if (std::size(hex) != TrSha1DigestStrlen)
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{
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return {};
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}
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if (!std::all_of(std::begin(hex), std::end(hex), [](unsigned char ch) { return isxdigit(ch); }))
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{
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return {};
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}
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auto digest = tr_sha1_digest_t{};
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tr_hex_to_binary(std::data(hex), std::data(digest), std::size(digest));
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return digest;
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}
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std::optional<tr_sha256_digest_t> tr_sha256_from_string(std::string_view hex)
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{
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using namespace hex_impl;
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if (std::size(hex) != TrSha256DigestStrlen)
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{
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return {};
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}
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if (!std::all_of(std::begin(hex), std::end(hex), [](unsigned char ch) { return isxdigit(ch); }))
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{
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return {};
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}
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auto digest = tr_sha256_digest_t{};
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tr_hex_to_binary(std::data(hex), std::data(digest), std::size(digest));
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return digest;
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}
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// fallback implementation in case the system crypto library's RNG fails
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void tr_rand_buffer_std(void* buffer, size_t length)
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{
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thread_local auto gen = std::mt19937{ std::random_device{}() };
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thread_local auto dist = std::uniform_int_distribution<unsigned long long>{};
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for (auto *walk = static_cast<uint8_t*>(buffer), *end = walk + length; walk < end;)
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{
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auto const tmp = dist(gen);
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auto const step = std::min(sizeof(tmp), static_cast<size_t>(end - walk));
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walk = std::copy_n(reinterpret_cast<uint8_t const*>(&tmp), step, walk);
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}
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}
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void tr_rand_buffer(void* buffer, size_t length)
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{
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if (!tr_rand_buffer_crypto(buffer, length))
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{
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tr_rand_buffer_std(buffer, length);
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}
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}
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