import gzip from datetime import timedelta from threading import RLock from .. import helpers as utils from ..crypto import AES from ..errors import BadMessageError, InvalidDCError, rpc_message_to_error from ..tl.all_tlobjects import tlobjects from ..tl.types import MsgsAck from ..extensions import BinaryReader, BinaryWriter import logging logging.getLogger(__name__).addHandler(logging.NullHandler()) class MtProtoSender: """MTProto Mobile Protocol sender (https://core.telegram.org/mtproto/description)""" def __init__(self, transport, session): self.transport = transport self.session = session self._logger = logging.getLogger(__name__) self._need_confirmation = [] # Message IDs that need confirmation self._pending_receive = [] # Requests sent waiting to be received # Store an RLock instance to make this class safely multi-threaded self._lock = RLock() # 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 def connect(self): """Connects to the server""" self.transport.connect() def is_connected(self): return self.transport.is_connected() def disconnect(self): """Disconnects from the server""" self.transport.close() # region Send and receive def send(self, request): """Sends the specified MTProtoRequest, previously sending any message which needed confirmation.""" # Now only us can be using this method with self._lock: self._logger.debug('send() acquired the lock') # If any message needs confirmation send an AckRequest first self._send_acknowledges() # Finally send our packed request with BinaryWriter() as writer: request.on_send(writer) self._send_packet(writer.get_bytes(), request) self._pending_receive.append(request) # And update the saved session self.session.save() self._logger.debug('send() released the lock') def _send_acknowledges(self): """Sends a messages acknowledge for all those who _need_confirmation""" 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[:] def receive(self, request=None, updates=None, **kwargs): """Receives the specified MTProtoRequest ("fills in it" the received data). This also restores the updates thread. An optional named parameter 'timeout' can be specified if one desires to override 'self.transport.timeout'. If 'request' is None, a single item will be read into the 'updates' list (which cannot be None). If 'request' is not None, any update received before reading the request's result will be put there unless it's None, in which case updates will be ignored. """ if request is None and updates is None: raise ValueError('Both the "request" and "updates"' 'parameters cannot be None at the same time.') with self._lock: self._logger.debug('receive() acquired the lock') # Don't stop trying to receive until we get the request we wanted # or, if there is no request, until we read an update while (request and not request.confirm_received) or \ (not request and not updates): self._logger.debug('Trying to .receive() the request result...') seq, body = self.transport.receive(**kwargs) message, remote_msg_id, remote_seq = self._decode_msg(body) with BinaryReader(message) as reader: self._process_msg( remote_msg_id, remote_seq, reader, updates) # We're done receiving, remove the request from pending, if any if request: try: self._pending_receive.remove(request) except ValueError: pass self._logger.debug('Request result received') self._logger.debug('receive() released the lock') def receive_updates(self, **kwargs): """Wrapper for .receive(request=None, updates=[])""" updates = [] self.receive(updates=updates, **kwargs) return updates def cancel_receive(self): """Cancels any pending receive operation by raising a ReadCancelledError""" self.transport.cancel_receive() # 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.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.request_msg_id) plain_writer.write_int( self.session.generate_sequence(request.content_related)) 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, updates): """Processes and handles a Telegram message. Returns True if the message was handled correctly and doesn't need to be skipped. Returns False otherwise. """ # 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) if code == 0x347773c5: # pong return self._handle_pong(msg_id, sequence, reader) if code == 0x73f1f8dc: # msg_container return self._handle_container(msg_id, sequence, reader, updates) if code == 0x3072cfa1: # gzip_packed return self._handle_gzip_packed(msg_id, sequence, reader, updates) if code == 0xedab447b: # bad_server_salt return self._handle_bad_server_salt(msg_id, sequence, reader) 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() for r in self._pending_receive: if r.request_msg_id in ack.msg_ids: self._logger.debug('Ack found for the a request') if self.logging_out: self._logger.debug('Message ack confirmed a request') r.confirm_received = True return True # 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: result = reader.tgread_object() if updates is None: self._logger.debug('Ignored update for %s', repr(result)) else: self._logger.debug('Read update for %s', repr(result)) updates.append(result) return True self._logger.debug('Unknown message: {}'.format(hex(code))) return False # endregion # region Message handling def _handle_pong(self, msg_id, sequence, reader): self._logger.debug('Handling pong') reader.read_int(signed=False) # code received_msg_id = reader.read_long() try: request = next(r for r in self._pending_receive if r.request_msg_id == received_msg_id) self._logger.debug('Pong confirmed a request') request.confirm_received = True except StopIteration: pass return True def _handle_container(self, msg_id, sequence, reader, updates): self._logger.debug('Handling container') reader.read_int(signed=False) # code size = reader.read_int() for _ in range(size): inner_msg_id = reader.read_long() reader.read_int() # inner_sequence inner_length = reader.read_int() begin_position = reader.tell_position() # Note that this code is IMPORTANT for skipping RPC results of # lost requests (i.e., ones from the previous connection session) try: if not self._process_msg( inner_msg_id, sequence, reader, updates): reader.set_position(begin_position + inner_length) except: # If any error is raised, something went wrong; skip the packet reader.set_position(begin_position + inner_length) raise return True def _handle_bad_server_salt(self, msg_id, sequence, reader): self._logger.debug('Handling bad server salt') reader.read_int(signed=False) # code bad_msg_id = reader.read_long() reader.read_int() # bad_msg_seq_no reader.read_int() # error_code new_salt = reader.read_long(signed=False) self.session.salt = new_salt try: request = next(r for r in self._pending_receive if r.request_msg_id == bad_msg_id) self.send(request) except StopIteration: pass return True def _handle_bad_msg_notification(self, msg_id, sequence, reader): self._logger.debug('Handling bad message notification') reader.read_int(signed=False) # code reader.read_long() # request_id reader.read_int() # request_sequence error_code = reader.read_int() error = BadMessageError(error_code) if error_code in (16, 17): # sent msg_id too low or too high (respectively). # Use the current msg_id to determine the right time offset. self.session.update_time_offset(correct_msg_id=msg_id) self.session.save() self._logger.debug('Read Bad Message error: ' + str(error)) self._logger.debug('Attempting to use the correct time offset.') return True else: raise error def _handle_rpc_result(self, msg_id, sequence, reader): self._logger.debug('Handling RPC result') reader.read_int(signed=False) # code request_id = reader.read_long() inner_code = reader.read_int(signed=False) try: request = next(r for r in self._pending_receive if r.request_msg_id == request_id) request.confirm_received = True except StopIteration: request = None if inner_code == 0x2144ca19: # RPC Error error = rpc_message_to_error( reader.read_int(), reader.tgread_string()) # Acknowledge that we received the error self._need_confirmation.append(request_id) self._send_acknowledges() self._logger.debug('Read RPC error: %s', str(error)) if isinstance(error, InvalidDCError): # Must resend this request, if any if request: request.confirm_received = False raise error else: if request: self._logger.debug('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) request.on_response(reader) return True else: # If it's really a result for RPC from previous connection # session, it will be skipped by the handle_container() self._logger.debug('Lost request will be skipped.') return False def _handle_gzip_packed(self, msg_id, sequence, reader, updates): self._logger.debug('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, updates) # endregion