MadelineProto/src/danog/MadelineProto/SecretChats/MessageHandler.php

<?php
/*
Copyright 2016-2017 Daniil Gentili
(https://daniil.it)
This file is part of MadelineProto.
MadelineProto is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
MadelineProto is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU Affero General Public License for more details.
You should have received a copy of the GNU General Public License along with MadelineProto.
If not, see <http://www.gnu.org/licenses/>.
*/

namespace danog\MadelineProto\SecretChats;

/**
 * Manages packing and unpacking of messages, and the list of sent and received messages.
 */
trait MessageHandler
{
    public function encrypt_secret_message($chat_id, $message)
    {
        if (!isset($this->secret_chats[$chat_id])) {
            \danog\MadelineProto\Logger::log('I do not have the secret chat '.$chat_id.' in the database, skipping message...');

            return false;
        }

        $this->secret_chats[$chat_id]['ttr']--;
        if (($this->secret_chats[$chat_id]['ttr'] <= 0 || time() - $this->secret_chats[$chat_id]['updated'] > 7 * 24 * 60 * 60) && $this->secret_chats[$chat_id]['rekeying'][0] === 0) {
            $this->rekey($chat_id);
        }
        if ($this->secret_chats[$chat_id]['layer'] !== 8) {
            $message = ['_' => 'decryptedMessageLayer', 'layer' => $this->secret_chats[$chat_id]['layer'], 'in_seq_no' => $this->generate_secret_in_seq_no($chat_id), 'out_seq_no' => $this->generate_secret_out_seq_no($chat_id), 'message' => $message];
        }
        $this->secret_chats[$chat_id]['outgoing'][$this->secret_chats[$chat_id]['out_seq_no']] = $message;
        $message = $this->serialize_object(['type' => $this->secret_chats[$chat_id]['layer'] === 8 ? 'DecryptedMessage' : 'DecryptedMessageLayer'], $message, $this->secret_chats[$chat_id]['layer']);
        $message = $this->pack_unsigned_int(strlen($message)).$message;

        $message_key = substr(sha1($message, true), -16);
        list($aes_key, $aes_iv) = $this->aes_calculate($message_key, $this->secret_chats[$chat_id]['key']['auth_key'], 'to server');

        $message .= $this->random($this->posmod(-strlen($message), 16));
        $this->secret_chats[$chat_id]['out_seq_no']++;

        $message = $this->secret_chats[$chat_id]['key']['fingerprint'].$message_key.$this->ige_encrypt($message, $aes_key, $aes_iv);

        return $message;
    }

    public function handle_encrypted_update($message)
    {
        if (!isset($this->secret_chats[$message['message']['chat_id']])) {
            \danog\MadelineProto\Logger::log('I do not have the secret chat '.$message['message']['chat_id'].' in the database, skipping message...');

            return false;
        }
        $auth_key_id = substr($message['message']['bytes'], 0, 8);
        $old = false;
        if ($auth_key_id !== $this->secret_chats[$message['message']['chat_id']]['key']['fingerprint']) {
            if (isset($this->secret_chats[$message['message']['chat_id']]['old_key']['fingerprint'])) {
                if ($auth_key_id !== $this->secret_chats[$message['message']['chat_id']]['old_key']['fingerprint']) {
                    throw new \danog\MadelineProto\SecurityException('Key fingerprint mismatch');
                }
                $old = true;
            } else {
                throw new \danog\MadelineProto\SecurityException('Key fingerprint mismatch');
            }
        }
        $message_key = substr($message['message']['bytes'], 8, 16);
        $encrypted_data = substr($message['message']['bytes'], 24);
        list($aes_key, $aes_iv) = $this->aes_calculate($message_key, $this->secret_chats[$message['message']['chat_id']][$old ? 'old_key' : 'key']['auth_key'], 'to server');
        $decrypted_data = $this->ige_decrypt($encrypted_data, $aes_key, $aes_iv);
        $message_data_length = unpack('V', substr($decrypted_data, 0, 4))[1];
        if ($message_data_length > strlen($decrypted_data)) {
            throw new \danog\MadelineProto\SecurityException('message_data_length is too big');
        }

        if ((strlen($decrypted_data) - 4) - $message_data_length > 15) {
            throw new \danog\MadelineProto\SecurityException('difference between message_data_length and the length of the remaining decrypted buffer is too big');
        }

        if (strlen($decrypted_data) % 16 != 0) {
            throw new \danog\MadelineProto\SecurityException('length of decrypted data is not divisible by 16');
        }
        $message_data = substr($decrypted_data, 4, $message_data_length);
        if ($message_key != substr(sha1(substr($decrypted_data, 0, 4 + $message_data_length), true), -16)) {
            throw new \danog\MadelineProto\SecurityException('msg_key mismatch');
        }
        $deserialized = $this->deserialize($message_data, ['type' => '']);
        $this->secret_chats[$message['message']['chat_id']]['ttr']--;
        if (($this->secret_chats[$message['message']['chat_id']]['ttr'] <= 0 || time() - $this->secret_chats[$message['message']['chat_id']]['updated'] > 7 * 24 * 60 * 60) && $this->secret_chats[$message['message']['chat_id']]['rekeying'][0] === 0) {
            $this->rekey($message['message']['chat_id']);
        }
        unset($message['message']['bytes']);
        $message['message']['decrypted_message'] = $deserialized;
        $this->secret_chats[$message['message']['chat_id']]['incoming'][$this->secret_chats[$message['message']['chat_id']]['in_seq_no']++] = $message['message'];
        $this->handle_decrypted_update($message);
    }
}