400 lines
12 KiB
C++
400 lines
12 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2017
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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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#pragma once
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#include "td/mtproto/AuthKey.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/Slice.h"
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#include "td/utils/Status.h"
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#include "td/utils/Time.h"
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#include <algorithm>
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#include <set>
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namespace td {
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namespace mtproto {
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struct ServerSalt {
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int64 salt;
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double valid_since;
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double valid_until;
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};
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template <class StorerT>
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void store(const ServerSalt &salt, StorerT &storer) {
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storer.template store_binary<int64>(salt.salt);
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storer.template store_binary<double>(salt.valid_since);
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storer.template store_binary<double>(salt.valid_until);
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}
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template <class ParserT>
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void parse(ServerSalt &salt, ParserT &parser) {
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salt.salt = parser.fetch_long();
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salt.valid_since = parser.fetch_double();
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salt.valid_until = parser.fetch_double();
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}
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class MessageIdDuplicateChecker {
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public:
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Status check(int64 message_id) {
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// In addition, the identifiers (msg_id) of the last N messages received from the other side must be stored, and if
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// a message comes in with msg_id lower than all or equal to any of the stored values, that message is to be
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// ignored. Otherwise, the new message msg_id is added to the set, and, if the number of stored msg_id values is
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// greater than N, the oldest (i. e. the lowest) is forgotten.
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if (saved_message_ids_.size() == MAX_SAVED_MESSAGE_IDS) {
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auto oldest_message_id = *saved_message_ids_.begin();
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if (message_id < oldest_message_id) {
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return Status::Error(1, PSLICE() << "Ignore very old message_id " << tag("oldest message_id", oldest_message_id)
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<< tag("got message_id", message_id));
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}
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}
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if (saved_message_ids_.count(message_id) != 0) {
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return Status::Error(1, PSLICE() << "Ignore duplicated_message id " << tag("message_id", message_id));
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}
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saved_message_ids_.insert(message_id);
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if (saved_message_ids_.size() > MAX_SAVED_MESSAGE_IDS) {
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saved_message_ids_.erase(saved_message_ids_.begin());
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}
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return Status::OK();
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}
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private:
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static constexpr size_t MAX_SAVED_MESSAGE_IDS = 1000;
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std::set<int64> saved_message_ids_;
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};
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class AuthData {
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public:
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AuthData() {
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server_salt_.salt = Random::secure_int64();
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server_salt_.valid_since = -1e10;
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server_salt_.valid_until = -1e10;
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}
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AuthData(const AuthData &) = delete;
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AuthData &operator=(const AuthData &) = delete;
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virtual ~AuthData() = default;
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bool is_ready(double now) {
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if (!has_main_auth_key()) {
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LOG(INFO) << "Need main auth key";
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return false;
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}
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if (use_pfs() && !has_tmp_auth_key(now)) {
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LOG(INFO) << "Need tmp auth key";
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return false;
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}
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if (!has_salt(now)) {
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LOG(INFO) << "no salt";
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return false;
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}
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return true;
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}
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uint64 session_id_;
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void set_main_auth_key(AuthKey auth_key) {
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main_auth_key_ = std::move(auth_key);
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}
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const AuthKey &get_main_auth_key() const {
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// CHECK(has_main_auth_key());
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return main_auth_key_;
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}
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bool has_main_auth_key() const {
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return !main_auth_key_.empty();
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}
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bool need_main_auth_key() const {
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return !has_main_auth_key();
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}
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void set_tmp_auth_key(AuthKey auth_key) {
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CHECK(!auth_key.empty());
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tmp_auth_key_ = std::move(auth_key);
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}
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const AuthKey &get_tmp_auth_key() const {
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// CHECK(has_tmp_auth_key());
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return tmp_auth_key_;
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}
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bool was_tmp_auth_key() const {
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return use_pfs() && !tmp_auth_key_.empty();
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}
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bool need_tmp_auth_key(double now) const {
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if (!use_pfs()) {
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return false;
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}
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if (tmp_auth_key_.empty()) {
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return true;
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}
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if (now > tmp_auth_key_.expire_at() - 60 * 60 * 2 /*2 hours*/) {
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return true;
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}
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if (!has_tmp_auth_key(now)) {
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return true;
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}
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return false;
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}
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void drop_main_auth_key() {
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main_auth_key_ = AuthKey();
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}
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void drop_tmp_auth_key() {
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tmp_auth_key_ = AuthKey();
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}
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bool has_tmp_auth_key(double now) const {
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if (!use_pfs()) {
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return false;
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}
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if (tmp_auth_key_.empty()) {
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return false;
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}
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if (now > tmp_auth_key_.expire_at() - 60 * 60 /*1 hour*/) {
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return false;
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}
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return true;
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}
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const AuthKey &get_auth_key() const {
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if (use_pfs()) {
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return get_tmp_auth_key();
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}
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return get_main_auth_key();
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}
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bool has_auth_key(double now) const {
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if (use_pfs()) {
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return has_tmp_auth_key(now);
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}
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return has_main_auth_key();
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}
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bool get_auth_flag() const {
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return main_auth_key_.auth_flag();
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}
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void set_auth_flag(bool auth_flag) {
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main_auth_key_.set_auth_flag(auth_flag);
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if (!auth_flag) {
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tmp_auth_key_.set_auth_flag(auth_flag);
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}
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}
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bool get_bind_flag() const {
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return !use_pfs() || tmp_auth_key_.auth_flag();
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}
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void on_bind() {
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CHECK(use_pfs());
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tmp_auth_key_.set_auth_flag(true);
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}
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Slice header() {
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if (use_pfs()) {
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return tmp_auth_key_.need_header() ? Slice(header_) : Slice();
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} else {
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return main_auth_key_.need_header() ? Slice(header_) : Slice();
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}
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}
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void set_header(std::string header) {
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header_ = std::move(header);
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}
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void on_api_response() {
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if (use_pfs()) {
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if (tmp_auth_key_.auth_flag()) {
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tmp_auth_key_.set_need_header(false);
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}
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} else {
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if (main_auth_key_.auth_flag()) {
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main_auth_key_.set_need_header(false);
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}
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}
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}
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uint64 get_session_id() const {
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return session_id_;
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}
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double get_server_time(double now) const {
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return server_time_difference_ + now;
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}
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double get_server_time_difference() const {
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return server_time_difference_;
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}
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// diff == msg_id / 2^32 - now == old_server_now - now <= server_now - now
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// server_time_difference >= max{diff}
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bool update_server_time_difference(double diff) {
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if (!server_time_difference_was_updated_) {
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server_time_difference_was_updated_ = true;
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LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
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server_time_difference_ = diff;
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} else if (server_time_difference_ + 1e-4 < diff) {
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LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
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server_time_difference_ = diff;
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} else {
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return false;
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}
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LOG(DEBUG) << "SERVER_TIME: " << format::as_hex(static_cast<int>(get_server_time(Time::now_cached())));
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return true;
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}
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void set_server_time_difference(double diff) {
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server_time_difference_was_updated_ = false;
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server_time_difference_ = diff;
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}
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uint64 get_server_salt(double now) {
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update_salt(now);
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return server_salt_.salt;
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}
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void set_server_salt(uint64 salt, double now) {
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server_salt_.salt = salt;
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double server_time = get_server_time(now);
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server_salt_.valid_since = server_time;
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server_salt_.valid_until = server_time + 60 * 10;
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future_salts_.clear();
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}
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bool is_server_salt_valid(double now) {
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return server_salt_.valid_until > get_server_time(now) + 60;
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}
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bool has_salt(double now) {
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update_salt(now);
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return is_server_salt_valid(now);
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}
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bool need_future_salts(double now) {
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update_salt(now);
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return future_salts_.empty() || !is_server_salt_valid(now);
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}
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virtual void set_future_salts(const std::vector<ServerSalt> &salts, double now) {
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if (salts.empty()) {
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return;
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}
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future_salts_ = salts;
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std::sort(future_salts_.begin(), future_salts_.end(),
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[](const ServerSalt &a, const ServerSalt &b) { return a.valid_since > b.valid_since; });
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update_salt(now);
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}
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std::vector<ServerSalt> get_future_salts() const {
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auto res = future_salts_;
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res.push_back(server_salt_);
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return res;
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}
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int64 next_message_id(double now) {
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double server_time = get_server_time(now);
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int64 t = static_cast<int64>(server_time * (1ll << 32));
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// randomize lower bits for clocks with low precision
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// TODO(perf) do not do this for systems with good precision?..
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auto rx = Random::secure_int32();
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auto to_xor = rx & ((1 << 22) - 1);
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auto to_mul = ((rx >> 22) & 1023) + 1;
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t ^= to_xor;
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auto result = t & -4;
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if (last_message_id_ >= result) {
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result = last_message_id_ + 8 * to_mul;
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}
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last_message_id_ = result;
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return result;
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}
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bool is_valid_outbound_msg_id(int64 id, double now) {
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double server_time = get_server_time(now);
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auto id_time = static_cast<double>(id / (1ll << 32));
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return server_time - 300 / 2 < id_time && id_time < server_time + 60 / 2;
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}
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bool is_valid_inbound_msg_id(int64 id, double now) {
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double server_time = get_server_time(now);
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auto id_time = static_cast<double>(id / (1ll << 32));
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return server_time - 300 < id_time && id_time < server_time + 30;
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}
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Status check_packet(int64 session_id, int64 message_id, double now, bool &time_difference_was_updated) {
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// Client is to check that the session_id field in the decrypted message indeed equals to that of an active session
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// created by the client.
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if (get_session_id() != static_cast<uint64>(session_id)) {
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return Status::Error(PSLICE() << "Got packet from different session "
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<< tag("current session_id", get_session_id())
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<< tag("got session_id", session_id));
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}
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// Client must check that msg_id has even parity for messages from client to server, and odd parity for messages
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// from server to client.
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if ((message_id & 1) == 0) {
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return Status::Error(PSLICE() << "Got invalid message_id " << tag("message_id", message_id));
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}
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TRY_STATUS(duplicate_checker_.check(message_id));
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time_difference_was_updated = update_server_time_difference(static_cast<uint32>(message_id >> 32) - now);
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// In addition, msg_id values that belong over 30 seconds in the future or over 300 seconds in the past are to be
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// ignored (recall that msg_id approximately equals unixtime * 2^32). This is especially important for the server.
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// The client would also find this useful (to protect from a replay attack), but only if it is certain of its time
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// (for example, if its time has been synchronized with that of the server).
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if (server_time_difference_was_updated_ && !is_valid_inbound_msg_id(message_id, now)) {
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return Status::Error(PSLICE() << "Ignore message with too old or too new message_id "
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<< tag("message_id", message_id));
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}
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return Status::OK();
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}
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Status check_update(int64 message_id) {
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return updates_duplicate_checker_.check(message_id);
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}
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int32 next_seq_no(bool is_content_related) {
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int32 res = seq_no_;
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if (is_content_related) {
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res |= 1;
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seq_no_ += 2;
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}
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return res;
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}
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void clear_seq_no() {
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seq_no_ = 0;
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}
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void set_use_pfs(bool use_pfs) {
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use_pfs_ = use_pfs;
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}
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bool use_pfs() const {
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return use_pfs_;
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}
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private:
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bool use_pfs_ = true;
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AuthKey main_auth_key_;
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AuthKey tmp_auth_key_;
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bool server_time_difference_was_updated_ = false;
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double server_time_difference_ = 0;
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ServerSalt server_salt_;
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int64 last_message_id_ = 0;
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int32 seq_no_ = 0;
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std::string header_;
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std::vector<ServerSalt> future_salts_;
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MessageIdDuplicateChecker duplicate_checker_;
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MessageIdDuplicateChecker updates_duplicate_checker_;
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void update_salt(double now) {
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double server_time = get_server_time(now);
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while (!future_salts_.empty() && (future_salts_.back().valid_since < server_time)) {
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server_salt_ = future_salts_.back();
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future_salts_.pop_back();
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}
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}
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};
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} // namespace mtproto
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} // namespace td
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