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tdlib-fork/td/mtproto/AuthData.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/mtproto/AuthKey.h"
#include "td/utils/format.h"
#include "td/utils/logging.h"
#include "td/utils/Random.h"
#include "td/utils/Slice.h"
#include "td/utils/Status.h"
#include "td/utils/Time.h"
#include <algorithm>
#include <set>
namespace td {
namespace mtproto {
struct ServerSalt {
int64 salt;
double valid_since;
double valid_until;
};
template <class StorerT>
void store(const ServerSalt &salt, StorerT &storer) {
storer.template store_binary<int64>(salt.salt);
storer.template store_binary<double>(salt.valid_since);
storer.template store_binary<double>(salt.valid_until);
}
template <class ParserT>
void parse(ServerSalt &salt, ParserT &parser) {
salt.salt = parser.fetch_long();
salt.valid_since = parser.fetch_double();
salt.valid_until = parser.fetch_double();
}
class MessageIdDuplicateChecker {
public:
Status check(int64 message_id) {
// In addition, the identifiers (msg_id) of the last N messages received from the other side must be stored, and if
// a message comes in with msg_id lower than all or equal to any of the stored values, that message is to be
// ignored. Otherwise, the new message msg_id is added to the set, and, if the number of stored msg_id values is
// greater than N, the oldest (i. e. the lowest) is forgotten.
if (saved_message_ids_.size() == MAX_SAVED_MESSAGE_IDS) {
auto oldest_message_id = *saved_message_ids_.begin();
if (message_id < oldest_message_id) {
return Status::Error(1, PSLICE() << "Ignore very old message_id " << tag("oldest message_id", oldest_message_id)
<< tag("got message_id", message_id));
}
}
if (saved_message_ids_.count(message_id) != 0) {
return Status::Error(1, PSLICE() << "Ignore duplicated_message id " << tag("message_id", message_id));
}
saved_message_ids_.insert(message_id);
if (saved_message_ids_.size() > MAX_SAVED_MESSAGE_IDS) {
saved_message_ids_.erase(saved_message_ids_.begin());
}
return Status::OK();
}
private:
static constexpr size_t MAX_SAVED_MESSAGE_IDS = 1000;
std::set<int64> saved_message_ids_;
};
class AuthData {
public:
AuthData() {
server_salt_.salt = Random::secure_int64();
server_salt_.valid_since = -1e10;
server_salt_.valid_until = -1e10;
}
AuthData(const AuthData &) = delete;
AuthData &operator=(const AuthData &) = delete;
virtual ~AuthData() = default;
bool is_ready(double now) {
if (!has_main_auth_key()) {
LOG(INFO) << "Need main auth key";
return false;
}
if (use_pfs() && !has_tmp_auth_key(now)) {
LOG(INFO) << "Need tmp auth key";
return false;
}
if (!has_salt(now)) {
LOG(INFO) << "no salt";
return false;
}
return true;
}
uint64 session_id_;
void set_main_auth_key(AuthKey auth_key) {
main_auth_key_ = std::move(auth_key);
}
const AuthKey &get_main_auth_key() const {
// CHECK(has_main_auth_key());
return main_auth_key_;
}
bool has_main_auth_key() const {
return !main_auth_key_.empty();
}
bool need_main_auth_key() const {
return !has_main_auth_key();
}
void set_tmp_auth_key(AuthKey auth_key) {
CHECK(!auth_key.empty());
tmp_auth_key_ = std::move(auth_key);
}
const AuthKey &get_tmp_auth_key() const {
// CHECK(has_tmp_auth_key());
return tmp_auth_key_;
}
bool was_tmp_auth_key() const {
return use_pfs() && !tmp_auth_key_.empty();
}
bool need_tmp_auth_key(double now) const {
if (!use_pfs()) {
return false;
}
if (tmp_auth_key_.empty()) {
return true;
}
if (now > tmp_auth_key_.expire_at() - 60 * 60 * 2 /*2 hours*/) {
return true;
}
if (!has_tmp_auth_key(now)) {
return true;
}
return false;
}
void drop_main_auth_key() {
main_auth_key_ = AuthKey();
}
void drop_tmp_auth_key() {
tmp_auth_key_ = AuthKey();
}
bool has_tmp_auth_key(double now) const {
if (!use_pfs()) {
return false;
}
if (tmp_auth_key_.empty()) {
return false;
}
if (now > tmp_auth_key_.expire_at() - 60 * 60 /*1 hour*/) {
return false;
}
return true;
}
const AuthKey &get_auth_key() const {
if (use_pfs()) {
return get_tmp_auth_key();
}
return get_main_auth_key();
}
bool has_auth_key(double now) const {
if (use_pfs()) {
return has_tmp_auth_key(now);
}
return has_main_auth_key();
}
bool get_auth_flag() const {
return main_auth_key_.auth_flag();
}
void set_auth_flag(bool auth_flag) {
main_auth_key_.set_auth_flag(auth_flag);
if (!auth_flag) {
tmp_auth_key_.set_auth_flag(auth_flag);
}
}
bool get_bind_flag() const {
return !use_pfs() || tmp_auth_key_.auth_flag();
}
void on_bind() {
CHECK(use_pfs());
tmp_auth_key_.set_auth_flag(true);
}
Slice header() {
if (use_pfs()) {
return tmp_auth_key_.need_header() ? Slice(header_) : Slice();
} else {
return main_auth_key_.need_header() ? Slice(header_) : Slice();
}
}
void set_header(std::string header) {
header_ = std::move(header);
}
void on_api_response() {
if (use_pfs()) {
if (tmp_auth_key_.auth_flag()) {
tmp_auth_key_.set_need_header(false);
}
} else {
if (main_auth_key_.auth_flag()) {
main_auth_key_.set_need_header(false);
}
}
}
uint64 get_session_id() const {
return session_id_;
}
double get_server_time(double now) const {
return server_time_difference_ + now;
}
double get_server_time_difference() const {
return server_time_difference_;
}
// diff == msg_id / 2^32 - now == old_server_now - now <= server_now - now
// server_time_difference >= max{diff}
bool update_server_time_difference(double diff) {
if (!server_time_difference_was_updated_) {
server_time_difference_was_updated_ = true;
LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
server_time_difference_ = diff;
} else if (server_time_difference_ + 1e-4 < diff) {
LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
server_time_difference_ = diff;
} else {
return false;
}
LOG(DEBUG) << "SERVER_TIME: " << format::as_hex(static_cast<int>(get_server_time(Time::now_cached())));
return true;
}
void set_server_time_difference(double diff) {
server_time_difference_was_updated_ = false;
server_time_difference_ = diff;
}
uint64 get_server_salt(double now) {
update_salt(now);
return server_salt_.salt;
}
void set_server_salt(uint64 salt, double now) {
server_salt_.salt = salt;
double server_time = get_server_time(now);
server_salt_.valid_since = server_time;
server_salt_.valid_until = server_time + 60 * 10;
future_salts_.clear();
}
bool is_server_salt_valid(double now) {
return server_salt_.valid_until > get_server_time(now) + 60;
}
bool has_salt(double now) {
update_salt(now);
return is_server_salt_valid(now);
}
bool need_future_salts(double now) {
update_salt(now);
return future_salts_.empty() || !is_server_salt_valid(now);
}
virtual void set_future_salts(const std::vector<ServerSalt> &salts, double now) {
if (salts.empty()) {
return;
}
future_salts_ = salts;
std::sort(future_salts_.begin(), future_salts_.end(),
[](const ServerSalt &a, const ServerSalt &b) { return a.valid_since > b.valid_since; });
update_salt(now);
}
std::vector<ServerSalt> get_future_salts() const {
auto res = future_salts_;
res.push_back(server_salt_);
return res;
}
int64 next_message_id(double now) {
double server_time = get_server_time(now);
int64 t = static_cast<int64>(server_time * (1ll << 32));
// randomize lower bits for clocks with low precision
// TODO(perf) do not do this for systems with good precision?..
auto rx = Random::secure_int32();
auto to_xor = rx & ((1 << 22) - 1);
auto to_mul = ((rx >> 22) & 1023) + 1;
t ^= to_xor;
auto result = t & -4;
if (last_message_id_ >= result) {
result = last_message_id_ + 8 * to_mul;
}
last_message_id_ = result;
return result;
}
bool is_valid_outbound_msg_id(int64 id, double now) {
double server_time = get_server_time(now);
auto id_time = static_cast<double>(id / (1ll << 32));
return server_time - 300 / 2 < id_time && id_time < server_time + 60 / 2;
}
bool is_valid_inbound_msg_id(int64 id, double now) {
double server_time = get_server_time(now);
auto id_time = static_cast<double>(id / (1ll << 32));
return server_time - 300 < id_time && id_time < server_time + 30;
}
Status check_packet(int64 session_id, int64 message_id, double now, bool &time_difference_was_updated) {
// Client is to check that the session_id field in the decrypted message indeed equals to that of an active session
// created by the client.
if (get_session_id() != static_cast<uint64>(session_id)) {
return Status::Error(PSLICE() << "Got packet from different session "
<< tag("current session_id", get_session_id())
<< tag("got session_id", session_id));
}
// Client must check that msg_id has even parity for messages from client to server, and odd parity for messages
// from server to client.
if ((message_id & 1) == 0) {
return Status::Error(PSLICE() << "Got invalid message_id " << tag("message_id", message_id));
}
TRY_STATUS(duplicate_checker_.check(message_id));
time_difference_was_updated = update_server_time_difference(static_cast<uint32>(message_id >> 32) - now);
// In addition, msg_id values that belong over 30 seconds in the future or over 300 seconds in the past are to be
// ignored (recall that msg_id approximately equals unixtime * 2^32). This is especially important for the server.
// The client would also find this useful (to protect from a replay attack), but only if it is certain of its time
// (for example, if its time has been synchronized with that of the server).
if (server_time_difference_was_updated_ && !is_valid_inbound_msg_id(message_id, now)) {
return Status::Error(PSLICE() << "Ignore message with too old or too new message_id "
<< tag("message_id", message_id));
}
return Status::OK();
}
Status check_update(int64 message_id) {
return updates_duplicate_checker_.check(message_id);
}
int32 next_seq_no(bool is_content_related) {
int32 res = seq_no_;
if (is_content_related) {
res |= 1;
seq_no_ += 2;
}
return res;
}
void clear_seq_no() {
seq_no_ = 0;
}
void set_use_pfs(bool use_pfs) {
use_pfs_ = use_pfs;
}
bool use_pfs() const {
return use_pfs_;
}
private:
bool use_pfs_ = true;
AuthKey main_auth_key_;
AuthKey tmp_auth_key_;
bool server_time_difference_was_updated_ = false;
double server_time_difference_ = 0;
ServerSalt server_salt_;
int64 last_message_id_ = 0;
int32 seq_no_ = 0;
std::string header_;
std::vector<ServerSalt> future_salts_;
MessageIdDuplicateChecker duplicate_checker_;
MessageIdDuplicateChecker updates_duplicate_checker_;
void update_salt(double now) {
double server_time = get_server_time(now);
while (!future_salts_.empty() && (future_salts_.back().valid_since < server_time)) {
server_salt_ = future_salts_.back();
future_salts_.pop_back();
}
}
};
} // namespace mtproto
} // namespace td