import gzip from datetime import timedelta from threading import Event, RLock, Thread from time import sleep, time import telethon.helpers as utils from telethon.crypto import AES from telethon.errors import * from telethon.log import Log from telethon.tl.all_tlobjects import tlobjects from telethon.tl.functions.updates import GetStateRequest from telethon.tl.types import MsgsAck from telethon.tl.functions import PingRequest from telethon.utils import BinaryReader, BinaryWriter class MtProtoSender: """MTProto Mobile Protocol sender (https://core.telegram.org/mtproto/description)""" def __init__(self, transport, session): self.transport = transport self.session = session self.need_confirmation = [] # Message IDs that need confirmation self.on_update_handlers = [] # Store an RLock instance to make this class safely multi-threaded self.lock = RLock() # Flag used to determine whether we've received a sent request yet or not # We need this to avoid using the updates thread if we're waiting to read self.waiting_receive = Event() # Used when logging out, the only request that seems to use 'ack' requests # TODO There might be a better way to handle msgs_ack requests self.logging_out = False self.ping_interval = 60 self.ping_time_last = time() # Flags used to determine the status of the updates thread. self.updates_thread_running = Event() self.updates_thread_receiving = Event() # Sleep amount on "must sleep" error for the updates thread to sleep too self.updates_thread_sleep = None self.updates_thread = Thread( name='UpdatesThread', daemon=True, target=self.updates_thread_method) self.connect() def connect(self): """Connects to the server""" self.transport.connect() # The "updates" thread must also be running to make periodic ping requests. self.set_updates_thread(running=True) def disconnect(self): """Disconnects and **stops all the running threads** if any""" self.set_updates_thread(running=False) self.transport.close() def reconnect(self): """Disconnects and connects again (effectively reconnecting)""" self.disconnect() self.connect() def add_update_handler(self, handler): """Adds an update handler (a method with one argument, the received TLObject) that is fired when there are updates available""" # The updates thread is already running for periodic ping requests, # so there is no need to start it when adding update handlers. self.on_update_handlers.append(handler) def remove_update_handler(self, handler): self.on_update_handlers.remove(handler) def generate_sequence(self, confirmed): """Generates the next sequence number, based on whether it was confirmed yet or not""" if confirmed: result = self.session.sequence * 2 + 1 self.session.sequence += 1 return result else: return self.session.sequence * 2 # region Send and receive def send_ping(self): """Sends PingRequest""" request = PingRequest(utils.generate_random_long()) self.send(request) self.receive(request) def send(self, request): """Sends the specified MTProtoRequest, previously sending any message which needed confirmation. This also pauses the updates thread""" # Only cancel the receive *if* it was the # updates thread who was receiving. We do # not want to cancel other pending requests! if self.updates_thread_receiving.is_set(): Log.i('Cancelling updates receive from send()...') self.transport.cancel_receive() # Now only us can be using this method with self.lock: Log.d('send() acquired the lock') # Set the flag to true so the updates thread stops trying to receive self.waiting_receive.set() # If any message needs confirmation send an AckRequest first if self.need_confirmation: msgs_ack = MsgsAck(self.need_confirmation) with BinaryWriter() as writer: msgs_ack.on_send(writer) self.send_packet(writer.get_bytes(), msgs_ack) del self.need_confirmation[:] # Finally send our packed request with BinaryWriter() as writer: request.on_send(writer) self.send_packet(writer.get_bytes(), request) # And update the saved session self.session.save() Log.d('send() released the lock') def receive(self, request, timeout=timedelta(seconds=5)): """Receives the specified MTProtoRequest ("fills in it" the received data). This also restores the updates thread. An optional timeout can be specified to cancel the operation if no data has been read after its time delta""" with self.lock: Log.d('receive() acquired the lock') # Don't stop trying to receive until we get the request we wanted while not request.confirm_received: Log.i('Trying to .receive() the request result...') seq, body = self.transport.receive(timeout) message, remote_msg_id, remote_sequence = self.decode_msg(body) with BinaryReader(message) as reader: self.process_msg(remote_msg_id, remote_sequence, reader, request) Log.i('Request result received') # We can now set the flag to False thus resuming the updates thread self.waiting_receive.clear() Log.d('receive() released the lock') # endregion # region Low level processing def send_packet(self, packet, request): """Sends the given packet bytes with the additional information of the original request. This does NOT lock the threads!""" request.msg_id = self.session.get_new_msg_id() # First calculate plain_text to encrypt it with BinaryWriter() as plain_writer: plain_writer.write_long(self.session.salt, signed=False) plain_writer.write_long(self.session.id, signed=False) plain_writer.write_long(request.msg_id) plain_writer.write_int(self.generate_sequence(request.confirmed)) plain_writer.write_int(len(packet)) plain_writer.write(packet) msg_key = utils.calc_msg_key(plain_writer.get_bytes()) key, iv = utils.calc_key(self.session.auth_key.key, msg_key, True) cipher_text = AES.encrypt_ige(plain_writer.get_bytes(), key, iv) # And then finally send the encrypted packet with BinaryWriter() as cipher_writer: cipher_writer.write_long( self.session.auth_key.key_id, signed=False) cipher_writer.write(msg_key) cipher_writer.write(cipher_text) self.transport.send(cipher_writer.get_bytes()) def decode_msg(self, body): """Decodes an received encrypted message body bytes""" message = None remote_msg_id = None remote_sequence = None with BinaryReader(body) as reader: if len(body) < 8: raise BufferError("Can't decode packet ({})".format(body)) # TODO Check for both auth key ID and msg_key correctness reader.read_long() # remote_auth_key_id msg_key = reader.read(16) key, iv = utils.calc_key(self.session.auth_key.key, msg_key, False) plain_text = AES.decrypt_ige( reader.read(len(body) - reader.tell_position()), key, iv) with BinaryReader(plain_text) as plain_text_reader: plain_text_reader.read_long() # remote_salt plain_text_reader.read_long() # remote_session_id remote_msg_id = plain_text_reader.read_long() remote_sequence = plain_text_reader.read_int() msg_len = plain_text_reader.read_int() message = plain_text_reader.read(msg_len) return message, remote_msg_id, remote_sequence def process_msg(self, msg_id, sequence, reader, request=None): """Processes and handles a Telegram message""" # TODO Check salt, session_id and sequence_number self.need_confirmation.append(msg_id) code = reader.read_int(signed=False) reader.seek(-4) # The following codes are "parsed manually" if code == 0xf35c6d01: # rpc_result, (response of an RPC call, i.e., we sent a request) return self.handle_rpc_result(msg_id, sequence, reader, request) if code == 0x347773c5: # pong return self.handle_pong(msg_id, sequence, reader, request) if code == 0x73f1f8dc: # msg_container return self.handle_container(msg_id, sequence, reader, request) if code == 0x3072cfa1: # gzip_packed return self.handle_gzip_packed(msg_id, sequence, reader, request) if code == 0xedab447b: # bad_server_salt return self.handle_bad_server_salt(msg_id, sequence, reader, request) if code == 0xa7eff811: # bad_msg_notification return self.handle_bad_msg_notification(msg_id, sequence, reader) # msgs_ack, it may handle the request we wanted if code == 0x62d6b459: ack = reader.tgread_object() if request and request.msg_id in ack.msg_ids: Log.w('Ack found for the current request ID') if self.logging_out: Log.i('Message ack confirmed the logout request') request.confirm_received = True return False # If the code is not parsed manually, then it was parsed by the code generator! # In this case, we will simply treat the incoming TLObject as an Update, # if we can first find a matching TLObject if code in tlobjects.keys(): return self.handle_update(msg_id, sequence, reader) print('Unknown message: {}'.format(hex(code))) return False # endregion # region Message handling def handle_update(self, msg_id, sequence, reader): tlobject = reader.tgread_object() Log.d('Handling update for object %s', repr(tlobject)) for handler in self.on_update_handlers: handler(tlobject) return False def handle_pong(self, msg_id, sequence, reader, request): Log.d('Handling pong') reader.read_int(signed=False) # code recv_msg_id = reader.read_long(signed=False) if recv_msg_id == request.msg_id: Log.w('Pong confirmed a request') request.confirm_received = True return False def handle_container(self, msg_id, sequence, reader, request): Log.d('Handling container') reader.read_int(signed=False) # code size = reader.read_int() for _ in range(size): inner_msg_id = reader.read_long(signed=False) reader.read_int() # inner_sequence inner_length = reader.read_int() begin_position = reader.tell_position() # note: this code is IMPORTANT for skipping RPC results of lost # requests (for example, ones from the previous connection session) if not self.process_msg(inner_msg_id, sequence, reader, request): reader.set_position(begin_position + inner_length) return False def handle_bad_server_salt(self, msg_id, sequence, reader, request): Log.d('Handling bad server salt') reader.read_int(signed=False) # code reader.read_long(signed=False) # bad_msg_id reader.read_int() # bad_msg_seq_no reader.read_int() # error_code new_salt = reader.read_long(signed=False) self.session.salt = new_salt if request is None: raise ValueError( 'Tried to handle a bad server salt with no request specified') # Resend self.send(request) return True def handle_bad_msg_notification(self, msg_id, sequence, reader): Log.d('Handling bad message notification') reader.read_int(signed=False) # code reader.read_long(signed=False) # request_id reader.read_int() # request_sequence error_code = reader.read_int() raise BadMessageError(error_code) def handle_rpc_result(self, msg_id, sequence, reader, request): Log.d('Handling RPC result, request is%s None', ' not' if request else '') reader.read_int(signed=False) # code request_id = reader.read_long(signed=False) inner_code = reader.read_int(signed=False) if request and request_id == request.msg_id: request.confirm_received = True if inner_code == 0x2144ca19: # RPC Error error = RPCError( code=reader.read_int(), message=reader.tgread_string()) Log.w('Read RPC error: %s', str(error)) if error.must_resend: if not request: raise ValueError( 'The previously sent request must be resent. ' 'However, no request was previously sent (called from updates thread).') request.confirm_received = False if error.message.startswith('FLOOD_WAIT_'): self.updates_thread_sleep = error.additional_data print('Should wait {}s. Sleeping until then.'.format( error.additional_data)) sleep(error.additional_data) elif '_MIGRATE_' in error.message: raise InvalidDCError(error.additional_data) else: raise error else: if not request: raise ValueError( 'Cannot receive a request from inside an RPC result from the updates thread.') Log.d('Reading request response') if inner_code == 0x3072cfa1: # GZip packed unpacked_data = gzip.decompress(reader.tgread_bytes()) with BinaryReader(unpacked_data) as compressed_reader: request.on_response(compressed_reader) else: reader.seek(-4) if request_id == request.msg_id: request.on_response(reader) else: # note: if it's really a result for RPC from previous connection # session, it will be skipped by the handle_container() Log.w('RPC result found for unknown request (maybe from previous connection session)') def handle_gzip_packed(self, msg_id, sequence, reader, request): Log.d('Handling gzip packed data') reader.read_int(signed=False) # code packed_data = reader.tgread_bytes() unpacked_data = gzip.decompress(packed_data) with BinaryReader(unpacked_data) as compressed_reader: return self.process_msg(msg_id, sequence, compressed_reader, request) # endregion def set_updates_thread(self, running): """Sets the updates thread status (running or not)""" if running == self.updates_thread_running.is_set(): return # Different state, update the saved value and behave as required Log.i('Changing updates thread running status to %s', running) if running: self.updates_thread_running.set() self.updates_thread.start() else: self.updates_thread_running.clear() if self.updates_thread_receiving.is_set(): self.transport.cancel_receive() def updates_thread_method(self): """This method will run until specified and listen for incoming updates""" # Set a reasonable timeout when checking for updates timeout = timedelta(minutes=1) while self.updates_thread_running.is_set(): # Always sleep a bit before each iteration to relax the CPU, # since it's possible to early 'continue' the loop to reach # the next iteration, but we still should to sleep. if self.updates_thread_sleep: sleep(self.updates_thread_sleep) self.updates_thread_sleep = None else: # Longer sleep if we're not expecting updates (only pings) sleep(0.1 if self.on_update_handlers else 1) # Only try to receive updates if we're not waiting to receive a request if not self.waiting_receive.is_set(): with self.lock: Log.d('Updates thread acquired the lock') try: now = time() # If ping_interval seconds passed since last ping, send a new one if now >= self.ping_time_last + self.ping_interval: self.ping_time_last = now self.send_ping() Log.d('Ping sent from the updates thread') # Exit the loop if we're not expecting to receive any updates if not self.on_update_handlers: Log.d('No updates handlers found, continuing') continue self.updates_thread_receiving.set() Log.d('Trying to receive updates from the updates thread') seq, body = self.transport.receive(timeout) message, remote_msg_id, remote_sequence = self.decode_msg( body) Log.i('Received update from the updates thread') with BinaryReader(message) as reader: self.process_msg(remote_msg_id, remote_sequence, reader) except TimeoutError: Log.d('Receiving updates timed out') # TODO Workaround for issue #50 r = GetStateRequest() try: Log.d('Sending GetStateRequest (workaround for issue #50)') self.send(r) self.receive(r) except TimeoutError: Log.w('Timed out inside a timeout, trying to reconnect...') self.reconnect() self.send(r) self.receive(r) except ReadCancelledError: Log.i('Receiving updates cancelled') except OSError: Log.w('OSError on updates thread, %s logging out', 'was' if self.logging_out else 'was not') if self.logging_out: # This error is okay when logging out, means we got disconnected # TODO Not sure why this happens because we call disconnect()… self.set_updates_thread(running=False) else: raise Log.d('Updates thread released the lock') self.updates_thread_receiving.clear()