460 lines
16 KiB
C++
460 lines
16 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include "td/mtproto/Transport.h"
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#include "td/mtproto/AuthKey.h"
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#include "td/mtproto/crypto.h"
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#include "td/utils/as.h"
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#include "td/utils/crypto.h"
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#include "td/utils/format.h"
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#include "td/utils/logging.h"
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#include "td/utils/Random.h"
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#include "td/utils/Status.h"
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#include <array>
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#include <tuple>
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namespace td {
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namespace mtproto {
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#pragma pack(push, 4)
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#if TD_MSVC
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#pragma warning(push)
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#pragma warning(disable : 4200)
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#endif
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struct CryptoHeader {
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uint64 auth_key_id;
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UInt128 message_key;
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// encrypted part
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uint64 salt;
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uint64 session_id;
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// It is weird to generate message_id and seq_no while writing a packet.
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//
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// uint64 message_id;
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// uint32 seq_no;
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// uint32 message_data_length;
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uint8 data[0]; // use compiler extension
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static size_t encrypted_header_size() {
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return sizeof(salt) + sizeof(session_id);
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}
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uint8 *encrypt_begin() {
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return reinterpret_cast<uint8 *>(&salt);
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}
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const uint8 *encrypt_begin() const {
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return reinterpret_cast<const uint8 *>(&salt);
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}
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CryptoHeader() = delete;
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CryptoHeader(const CryptoHeader &) = delete;
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CryptoHeader(CryptoHeader &&) = delete;
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CryptoHeader &operator=(const CryptoHeader &) = delete;
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CryptoHeader &operator=(CryptoHeader &&) = delete;
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~CryptoHeader() = delete;
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};
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struct CryptoPrefix {
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uint64 message_id;
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uint32 seq_no;
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uint32 message_data_length;
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};
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struct EndToEndHeader {
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uint64 auth_key_id;
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UInt128 message_key;
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// encrypted part
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// uint32 message_data_length;
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uint8 data[0]; // use compiler extension
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static size_t encrypted_header_size() {
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return 0;
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}
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uint8 *encrypt_begin() {
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return reinterpret_cast<uint8 *>(&data);
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}
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const uint8 *encrypt_begin() const {
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return reinterpret_cast<const uint8 *>(&data);
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}
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EndToEndHeader() = delete;
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EndToEndHeader(const EndToEndHeader &) = delete;
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EndToEndHeader(EndToEndHeader &&) = delete;
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EndToEndHeader &operator=(const EndToEndHeader &) = delete;
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EndToEndHeader &operator=(EndToEndHeader &&) = delete;
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~EndToEndHeader() = delete;
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};
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struct EndToEndPrefix {
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uint32 message_data_length;
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};
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struct NoCryptoHeader {
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uint64 auth_key_id;
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// message_id is removed from CryptoHeader. Should be removed from here too.
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//
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// int64 message_id;
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// uint32 message_data_length;
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uint8 data[0]; // use compiler extension
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NoCryptoHeader() = delete;
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NoCryptoHeader(const NoCryptoHeader &) = delete;
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NoCryptoHeader(NoCryptoHeader &&) = delete;
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NoCryptoHeader &operator=(const NoCryptoHeader &) = delete;
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NoCryptoHeader &operator=(NoCryptoHeader &&) = delete;
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~NoCryptoHeader() = delete;
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};
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#if TD_MSVC
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#pragma warning(pop)
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#endif
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#pragma pack(pop)
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// mtproto v1.0
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template <class HeaderT>
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std::pair<uint32, UInt128> Transport::calc_message_ack_and_key(const HeaderT &head, size_t data_size) {
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Slice part(head.encrypt_begin(), head.data + data_size);
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UInt<160> message_sha1;
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sha1(part, message_sha1.raw);
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return std::make_pair(as<uint32>(message_sha1.raw) | (1u << 31), as<UInt128>(message_sha1.raw + 4));
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}
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template <class HeaderT>
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size_t Transport::calc_crypto_size(size_t data_size) {
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size_t enc_size = HeaderT::encrypted_header_size();
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size_t raw_size = sizeof(HeaderT) - enc_size;
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return raw_size + ((enc_size + data_size + 15) & ~15);
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}
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// mtproto v2.0
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std::pair<uint32, UInt128> Transport::calc_message_key2(const AuthKey &auth_key, int X, Slice to_encrypt) {
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// msg_key_large = SHA256 (substr (auth_key, 88+x, 32) + plaintext + random_padding);
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Sha256State state;
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sha256_init(&state);
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sha256_update(Slice(auth_key.key()).substr(88 + X, 32), &state);
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sha256_update(to_encrypt, &state);
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uint8 msg_key_large_raw[32];
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MutableSlice msg_key_large(msg_key_large_raw, sizeof(msg_key_large_raw));
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sha256_final(&state, msg_key_large);
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// msg_key = substr (msg_key_large, 8, 16);
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UInt128 res;
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as_slice(res).copy_from(msg_key_large.substr(8, 16));
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return std::make_pair(as<uint32>(msg_key_large_raw) | (1u << 31), res);
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}
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template <class HeaderT>
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size_t Transport::calc_crypto_size2(size_t data_size) {
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size_t enc_size = HeaderT::encrypted_header_size();
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size_t raw_size = sizeof(HeaderT) - enc_size;
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size_t encrypted_size = (enc_size + data_size + 12 + 15) & ~15;
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std::array<size_t, 10> sizes{{64, 128, 192, 256, 384, 512, 768, 1024, 1280}};
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for (auto size : sizes) {
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if (encrypted_size <= size) {
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return raw_size + size;
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}
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}
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encrypted_size = (encrypted_size - 1280 + 447) / 448 * 448 + 1280;
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return raw_size + encrypted_size;
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}
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size_t Transport::calc_no_crypto_size(size_t data_size) {
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return sizeof(NoCryptoHeader) + data_size;
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}
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Status Transport::read_no_crypto(MutableSlice message, PacketInfo *info, MutableSlice *data) {
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if (message.size() < sizeof(NoCryptoHeader)) {
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return Status::Error(PSLICE() << "Invalid mtproto message: too small [message.size() = " << message.size()
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<< "] < [sizeof(NoCryptoHeader) = " << sizeof(NoCryptoHeader) << "]");
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}
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size_t data_size = message.size() - sizeof(NoCryptoHeader);
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CHECK(message.size() == calc_no_crypto_size(data_size));
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*data = MutableSlice(message.begin() + sizeof(NoCryptoHeader), data_size);
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return Status::OK();
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}
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template <class HeaderT, class PrefixT>
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Status Transport::read_crypto_impl(int X, MutableSlice message, const AuthKey &auth_key, HeaderT **header_ptr,
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PrefixT **prefix_ptr, MutableSlice *data, PacketInfo *info) {
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if (message.size() < sizeof(HeaderT)) {
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return Status::Error(PSLICE() << "Invalid mtproto message: too small [message.size() = " << message.size()
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<< "] < [sizeof(HeaderT) = " << sizeof(HeaderT) << "]");
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}
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//FIXME: rewrite without reinterpret cast
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auto *header = reinterpret_cast<HeaderT *>(message.begin());
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*header_ptr = header;
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auto to_decrypt = MutableSlice(header->encrypt_begin(), message.uend());
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to_decrypt = to_decrypt.truncate(to_decrypt.size() & ~15);
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if (to_decrypt.size() % 16 != 0) {
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return Status::Error(PSLICE() << "Invalid mtproto message: size of encrypted part is not multiple of 16 [size = "
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<< to_decrypt.size() << "]");
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}
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if (header->auth_key_id != auth_key.id()) {
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return Status::Error(PSLICE() << "Invalid mtproto message: auth_key_id mismatch [found = "
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<< format::as_hex(header->auth_key_id)
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<< "] [expected = " << format::as_hex(auth_key.id()) << "]");
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}
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UInt256 aes_key;
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UInt256 aes_iv;
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if (info->version == 1) {
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KDF(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
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} else {
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KDF2(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
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}
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aes_ige_decrypt(aes_key, &aes_iv, to_decrypt, to_decrypt);
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size_t tail_size = message.end() - reinterpret_cast<char *>(header->data);
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if (tail_size < sizeof(PrefixT)) {
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return Status::Error("Too small encrypted part");
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}
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//FIXME: rewrite without reinterpret cast
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auto *prefix = reinterpret_cast<PrefixT *>(header->data);
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*prefix_ptr = prefix;
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size_t data_size = prefix->message_data_length + sizeof(PrefixT);
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bool is_length_ok = true;
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UInt128 real_message_key;
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if (info->version == 1) {
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is_length_ok &= !info->check_mod4 || prefix->message_data_length % 4 == 0;
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auto expected_size = calc_crypto_size<HeaderT>(data_size);
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is_length_ok = (is_length_ok & (expected_size == message.size())) != 0;
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auto check_size = data_size * is_length_ok + tail_size * (1 - is_length_ok);
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std::tie(info->message_ack, real_message_key) = calc_message_ack_and_key(*header, check_size);
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} else {
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std::tie(info->message_ack, real_message_key) = calc_message_key2(auth_key, X, to_decrypt);
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}
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bool is_key_ok = true;
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for (size_t i = 0; i < sizeof(real_message_key.raw); i++) {
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is_key_ok &= real_message_key.raw[i] == header->message_key.raw[i];
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}
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if (!is_key_ok) {
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return Status::Error(PSLICE() << "Invalid mtproto message: message_key mismatch [found = "
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<< format::as_hex_dump(header->message_key)
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<< "] [expected = " << format::as_hex_dump(real_message_key) << "]");
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}
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if (info->version == 2) {
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if (info->check_mod4 && prefix->message_data_length % 4 != 0) {
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return Status::Error(PSLICE() << "Invalid mtproto message: invalid length (not divisible by four)"
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<< tag("total_size", message.size())
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<< tag("message_data_length", prefix->message_data_length));
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}
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if (tail_size - sizeof(PrefixT) < prefix->message_data_length) {
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return Status::Error(PSLICE() << "Invalid mtproto message: invalid length (message_data_length is too big)"
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<< tag("total_size", message.size())
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<< tag("message_data_length", prefix->message_data_length));
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}
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size_t pad_size = tail_size - data_size;
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if (pad_size < 12 || pad_size > 1024) {
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return Status::Error(PSLICE() << "Invalid mtproto message: invalid length (invalid padding length)"
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<< tag("padding_size", pad_size) << tag("total_size", message.size())
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<< tag("message_data_length", prefix->message_data_length));
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}
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} else {
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if (!is_length_ok) {
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return Status::Error(PSLICE() << "Invalid mtproto message: invalid length " << tag("total_size", message.size())
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<< tag("message_data_length", prefix->message_data_length));
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}
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}
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*data = MutableSlice(header->data, data_size);
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return Status::OK();
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}
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Status Transport::read_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data) {
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CryptoHeader *header = nullptr;
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CryptoPrefix *prefix = nullptr;
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TRY_STATUS(read_crypto_impl(8, message, auth_key, &header, &prefix, data, info));
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CHECK(header != nullptr);
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CHECK(prefix != nullptr);
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CHECK(info != nullptr);
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info->type = PacketInfo::Common;
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info->salt = header->salt;
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info->session_id = header->session_id;
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info->message_id = prefix->message_id;
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info->seq_no = prefix->seq_no;
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return Status::OK();
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}
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Status Transport::read_e2e_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data) {
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EndToEndHeader *header = nullptr;
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EndToEndPrefix *prefix = nullptr;
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TRY_STATUS(read_crypto_impl(info->is_creator && info->version != 1 ? 8 : 0, message, auth_key, &header, &prefix, data,
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info));
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CHECK(header != nullptr);
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CHECK(prefix != nullptr);
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CHECK(info != nullptr);
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info->type = PacketInfo::EndToEnd;
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return Status::OK();
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}
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size_t Transport::write_no_crypto(const Storer &storer, PacketInfo *info, MutableSlice dest) {
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size_t size = calc_no_crypto_size(storer.size());
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if (size > dest.size()) {
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return size;
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}
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// NoCryptoHeader
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as<uint64>(dest.begin()) = uint64(0);
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auto real_size = storer.store(dest.ubegin() + sizeof(uint64));
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CHECK(real_size == storer.size());
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return size;
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}
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template <class HeaderT>
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void Transport::write_crypto_impl(int X, const Storer &storer, const AuthKey &auth_key, PacketInfo *info,
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HeaderT *header, size_t data_size) {
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auto real_data_size = storer.store(header->data);
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CHECK(real_data_size == data_size);
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VLOG(raw_mtproto) << "Send packet of size " << data_size << " to session " << format::as_hex(info->session_id) << ":"
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<< format::as_hex_dump<4>(Slice(header->data, data_size));
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size_t size = 0;
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if (info->version == 1) {
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size = calc_crypto_size<HeaderT>(data_size);
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} else {
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size = calc_crypto_size2<HeaderT>(data_size);
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}
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size_t pad_size = size - (sizeof(HeaderT) + data_size);
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MutableSlice pad(header->data + data_size, pad_size);
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Random::secure_bytes(pad.ubegin(), pad.size());
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MutableSlice to_encrypt = MutableSlice(header->encrypt_begin(), pad.uend());
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if (info->version == 1) {
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std::tie(info->message_ack, info->message_key) = calc_message_ack_and_key(*header, data_size);
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} else {
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std::tie(info->message_ack, info->message_key) = calc_message_key2(auth_key, X, to_encrypt);
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}
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header->message_key = info->message_key;
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UInt256 aes_key;
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UInt256 aes_iv;
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if (info->version == 1) {
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KDF(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
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} else {
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KDF2(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
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}
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aes_ige_encrypt(aes_key, &aes_iv, to_encrypt, to_encrypt);
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}
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size_t Transport::write_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
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size_t data_size = storer.size();
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size_t size;
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if (info->version == 1) {
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size = calc_crypto_size<CryptoHeader>(data_size);
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} else {
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size = calc_crypto_size2<CryptoHeader>(data_size);
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}
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if (size > dest.size()) {
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return size;
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}
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//FIXME: rewrite without reinterpret cast
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auto &header = *reinterpret_cast<CryptoHeader *>(dest.begin());
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header.auth_key_id = auth_key.id();
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header.salt = info->salt;
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header.session_id = info->session_id;
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write_crypto_impl(0, storer, auth_key, info, &header, data_size);
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return size;
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}
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size_t Transport::write_e2e_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
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size_t data_size = storer.size();
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size_t size;
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if (info->version == 1) {
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size = calc_crypto_size<EndToEndHeader>(data_size);
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} else {
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size = calc_crypto_size2<EndToEndHeader>(data_size);
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}
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if (size > dest.size()) {
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return size;
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}
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//FIXME: rewrite without reinterpret cast
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auto &header = *reinterpret_cast<EndToEndHeader *>(dest.begin());
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header.auth_key_id = auth_key.id();
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write_crypto_impl(info->is_creator || info->version == 1 ? 0 : 8, storer, auth_key, info, &header, data_size);
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return size;
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}
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Result<uint64> Transport::read_auth_key_id(Slice message) {
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if (message.size() < 8) {
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return Status::Error(PSLICE() << "Invalid mtproto message: smaller than 8 bytes [size = " << message.size() << "]");
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}
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return as<uint64>(message.begin());
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}
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Result<Transport::ReadResult> Transport::read(MutableSlice message, const AuthKey &auth_key, PacketInfo *info) {
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if (message.size() < 12) {
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if (message.size() < 4) {
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return Status::Error(PSLICE() << "Invalid mtproto message: smaller than 4 bytes [size = " << message.size()
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<< "]");
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}
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int32 code = as<int32>(message.begin());
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if (code == 0) {
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return ReadResult::make_nop();
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} else if (code == -1 && message.size() >= 8) {
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return ReadResult::make_quick_ack(as<uint32>(message.begin() + 4));
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} else {
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return ReadResult::make_error(code);
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}
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}
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info->auth_key_id = as<int64>(message.begin());
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info->no_crypto_flag = info->auth_key_id == 0;
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MutableSlice data;
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if (info->type == PacketInfo::EndToEnd) {
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TRY_STATUS(read_e2e_crypto(message, auth_key, info, &data));
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} else if (info->no_crypto_flag) {
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TRY_STATUS(read_no_crypto(message, info, &data));
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} else {
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if (auth_key.empty()) {
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return Status::Error("Failed to decrypt mtproto message: auth key is empty");
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}
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TRY_STATUS(read_crypto(message, auth_key, info, &data));
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}
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return ReadResult::make_packet(data);
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}
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size_t Transport::write(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
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if (info->type == PacketInfo::EndToEnd) {
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return write_e2e_crypto(storer, auth_key, info, dest);
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}
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if (info->no_crypto_flag) {
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return write_no_crypto(storer, info, dest);
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} else {
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CHECK(!auth_key.empty());
|
|
return write_crypto(storer, auth_key, info, dest);
|
|
}
|
|
}
|
|
|
|
} // namespace mtproto
|
|
} // namespace td
|