import asyncio import logging from . import MTProtoPlainSender, authenticator from .. import utils from ..errors import ( BadMessageError, TypeNotFoundError, BrokenAuthKeyError, SecurityError, rpc_message_to_error ) from ..extensions import BinaryReader from ..tl.core import RpcResult, MessageContainer, GzipPacked from ..tl.functions.auth import LogOutRequest from ..tl.types import ( MsgsAck, Pong, BadServerSalt, BadMsgNotification, FutureSalts, MsgNewDetailedInfo, NewSessionCreated, MsgDetailedInfo, MsgsStateReq, MsgsStateInfo, MsgsAllInfo, MsgResendReq ) __log__ = logging.getLogger(__name__) # Place this object in the send queue when a reconnection is needed # so there is an item to read and we can early quit the loop, since # without this it will block until there's something in the queue. _reconnect_sentinel = object() class MTProtoSender: """ MTProto Mobile Protocol sender (https://core.telegram.org/mtproto/description). This class is responsible for wrapping requests into `TLMessage`'s, sending them over the network and receiving them in a safe manner. Automatic reconnection due to temporary network issues is a concern for this class as well, including retry of messages that could not be sent successfully. A new authorization key will be generated on connection if no other key exists yet. """ def __init__(self, state, connection, loop, *, retries=5, auto_reconnect=True, update_callback=None, auth_key_callback=None, auto_reconnect_callback=None): self.state = state self._connection = connection self._loop = loop self._ip = None self._port = None self._retries = retries self._auto_reconnect = auto_reconnect self._update_callback = update_callback self._auth_key_callback = auth_key_callback self._auto_reconnect_callback = auto_reconnect_callback # Whether the user has explicitly connected or disconnected. # # If a disconnection happens for any other reason and it # was *not* user action then the pending messages won't # be cleared but on explicit user disconnection all the # pending futures should be cancelled. self._user_connected = False self._reconnecting = False self._disconnected = None # We need to join the loops upon disconnection self._send_loop_handle = None self._recv_loop_handle = None # Sending something shouldn't block self._send_queue = _ContainerQueue() # Telegram responds to messages out of order. Keep # {id: Message} to set their Future result upon arrival. self._pending_messages = {} # Containers are accepted or rejected as a whole when any of # its inner requests are acknowledged. For this purpose we # all the sent containers here. self._pending_containers = [] # We need to acknowledge every response from Telegram self._pending_ack = set() # Similar to pending_messages but only for the last ack. # Ack can't be put in the messages because Telegram never # responds to acknowledges (they're just that, acknowledges), # so it would grow to infinite otherwise, but on bad salt it's # necessary to resend them just like everything else. self._last_ack = None # Jump table from response ID to method that handles it self._handlers = { RpcResult.CONSTRUCTOR_ID: self._handle_rpc_result, MessageContainer.CONSTRUCTOR_ID: self._handle_container, GzipPacked.CONSTRUCTOR_ID: self._handle_gzip_packed, Pong.CONSTRUCTOR_ID: self._handle_pong, BadServerSalt.CONSTRUCTOR_ID: self._handle_bad_server_salt, BadMsgNotification.CONSTRUCTOR_ID: self._handle_bad_notification, MsgDetailedInfo.CONSTRUCTOR_ID: self._handle_detailed_info, MsgNewDetailedInfo.CONSTRUCTOR_ID: self._handle_new_detailed_info, NewSessionCreated.CONSTRUCTOR_ID: self._handle_new_session_created, MsgsAck.CONSTRUCTOR_ID: self._handle_ack, FutureSalts.CONSTRUCTOR_ID: self._handle_future_salts, MsgsStateReq.CONSTRUCTOR_ID: self._handle_state_forgotten, MsgResendReq.CONSTRUCTOR_ID: self._handle_state_forgotten, MsgsAllInfo.CONSTRUCTOR_ID: self._handle_msg_all, } # Public API async def connect(self, ip, port): """ Connects to the specified ``ip:port``, and generates a new authorization key for the `MTProtoSender.session` if it does not exist yet. """ if self._user_connected: __log__.info('User is already connected!') return self._ip = ip self._port = port self._user_connected = True await self._connect() def is_connected(self): return self._user_connected async def disconnect(self): """ Cleanly disconnects the instance from the network, cancels all pending requests, and closes the send and receive loops. """ if not self._user_connected: __log__.info('User is already disconnected!') return await self._disconnect() async def _disconnect(self, error=None): __log__.info('Disconnecting from {}...'.format(self._ip)) self._user_connected = False try: __log__.debug('Closing current connection...') await self._connection.close() finally: __log__.debug('Cancelling {} pending message(s)...' .format(len(self._pending_messages))) for message in self._pending_messages.values(): if error and not message.future.done(): message.future.set_exception(error) else: message.future.cancel() self._pending_messages.clear() self._pending_ack.clear() self._last_ack = None if self._send_loop_handle: __log__.debug('Cancelling the send loop...') self._send_loop_handle.cancel() if self._recv_loop_handle: __log__.debug('Cancelling the receive loop...') self._recv_loop_handle.cancel() __log__.info('Disconnection from {} complete!'.format(self._ip)) if self._disconnected: if error: self._disconnected.set_exception(error) else: self._disconnected.set_result(None) def send(self, request, ordered=False): """ This method enqueues the given request to be sent. The request will be wrapped inside a `TLMessage` until its response arrives, and the `Future` response of the `TLMessage` is immediately returned so that one can further ``await`` it: .. code-block:: python async def method(): # Sending (enqueued for the send loop) future = sender.send(request) # Receiving (waits for the receive loop to read the result) result = await future Designed like this because Telegram may send the response at any point, and it can send other items while one waits for it. Once the response for this future arrives, it is set with the received result, quite similar to how a ``receive()`` call would otherwise work. Since the receiving part is "built in" the future, it's impossible to await receive a result that was never sent. """ if not self._user_connected: raise ConnectionError('Cannot send requests while disconnected') if utils.is_list_like(request): result = [] after = None for r in request: message = self.state.create_message(r, after=after) self._pending_messages[message.msg_id] = message self._send_queue.put_nowait(message) result.append(message.future) after = ordered and message return result else: message = self.state.create_message(request) self._pending_messages[message.msg_id] = message self._send_queue.put_nowait(message) return message.future @property def disconnected(self): """ Future that resolves when the connection to Telegram ends, either by user action or in the background. """ if self._disconnected is not None: return asyncio.shield(self._disconnected, loop=self._loop) else: raise ConnectionError('Sender was never connected') # Private methods async def _connect(self): """ Performs the actual connection, retrying, generating the authorization key if necessary, and starting the send and receive loops. """ __log__.info('Connecting to {}:{}...'.format(self._ip, self._port)) for retry in range(1, self._retries + 1): try: __log__.debug('Connection attempt {}...'.format(retry)) await self._connection.connect(self._ip, self._port) except (asyncio.TimeoutError, OSError) as e: __log__.warning('Attempt {} at connecting failed: {}: {}' .format(retry, type(e).__name__, e)) else: break else: raise ConnectionError('Connection to Telegram failed {} times' .format(self._retries)) __log__.debug('Connection success!') if self.state.auth_key is None: plain = MTProtoPlainSender(self._connection) for retry in range(1, self._retries + 1): try: __log__.debug('New auth_key attempt {}...'.format(retry)) self.state.auth_key, self.state.time_offset =\ await authenticator.do_authentication(plain) if self._auth_key_callback: self._auth_key_callback(self.state.auth_key) break except (SecurityError, AssertionError) as e: __log__.warning('Attempt {} at new auth_key failed: {}' .format(retry, e)) else: e = ConnectionError('auth_key generation failed {} times' .format(self._retries)) await self._disconnect(error=e) raise e __log__.debug('Starting send loop') self._send_loop_handle = self._loop.create_task(self._send_loop()) __log__.debug('Starting receive loop') self._recv_loop_handle = self._loop.create_task(self._recv_loop()) # First connection or manual reconnection after a failure if self._disconnected is None or self._disconnected.done(): self._disconnected = asyncio.Future() __log__.info('Connection to {} complete!'.format(self._ip)) async def _reconnect(self): """ Cleanly disconnects and then reconnects. """ self._reconnecting = True self._send_queue.put_nowait(_reconnect_sentinel) __log__.debug('Awaiting for the send loop before reconnecting...') await self._send_loop_handle __log__.debug('Awaiting for the receive loop before reconnecting...') await self._recv_loop_handle __log__.debug('Closing current connection...') await self._connection.close() self._reconnecting = False retries = self._retries if self._auto_reconnect else 0 for retry in range(1, retries + 1): try: await self._connect() for m in self._pending_messages.values(): self._send_queue.put_nowait(m) if self._auto_reconnect_callback: self._loop.create_task(self._auto_reconnect_callback()) break except ConnectionError: __log__.info('Failed reconnection retry %d/%d', retry, retries) else: __log__.error('Failed to reconnect automatically.') await self._disconnect(error=ConnectionError()) def _start_reconnect(self): """Starts a reconnection in the background.""" if self._user_connected: self._loop.create_task(self._reconnect()) def _clean_containers(self, msg_ids): """ Helper method to clean containers from the pending messages once a wrapped msg_id of them has been acknowledged. This is the only way we can resend TLMessage(MessageContainer) on bad notifications and also mark them as received once any of their inner TLMessage is acknowledged. """ for i in reversed(range(len(self._pending_containers))): message = self._pending_containers[i] for msg in message.obj.messages: if msg.msg_id in msg_ids: del self._pending_containers[i] del self._pending_messages[message.msg_id] break # Loops async def _send_loop(self): """ This loop is responsible for popping items off the send queue, encrypting them, and sending them over the network. Besides `connect`, only this method ever sends data. """ while self._user_connected and not self._reconnecting: if self._pending_ack: self._last_ack = self.state.create_message( MsgsAck(list(self._pending_ack)) ) self._send_queue.put_nowait(self._last_ack) self._pending_ack.clear() messages = await self._send_queue.get() if messages == _reconnect_sentinel: if self._reconnecting: break else: continue if isinstance(messages, list): message = self.state.create_message(MessageContainer(messages)) self._pending_messages[message.msg_id] = message self._pending_containers.append(message) else: message = messages messages = [message] __log__.debug( 'Packing %d outgoing message(s) %s...', len(messages), ', '.join(x.obj.__class__.__name__ for x in messages) ) body = self.state.pack_message(message) while not any(m.future.cancelled() for m in messages): try: __log__.debug('Sending {} bytes...'.format(len(body))) await self._connection.send(body) break except asyncio.TimeoutError: continue except asyncio.CancelledError: return except Exception as e: if isinstance(e, ConnectionError): __log__.info('Connection reset while sending %s', e) elif isinstance(e, OSError): __log__.warning('OSError while sending %s', e) else: __log__.exception('Unhandled exception while receiving') await asyncio.sleep(1) self._start_reconnect() break else: # Remove the cancelled messages from pending __log__.info('Some futures were cancelled, aborted send') self._clean_containers([m.msg_id for m in messages]) for m in messages: if m.future.cancelled(): self._pending_messages.pop(m.msg_id, None) else: self._send_queue.put_nowait(m) __log__.debug('Outgoing messages {} sent!' .format(', '.join(str(m.msg_id) for m in messages))) async def _recv_loop(self): """ This loop is responsible for reading all incoming responses from the network, decrypting and handling or dispatching them. Besides `connect`, only this method ever receives data. """ while self._user_connected and not self._reconnecting: try: __log__.debug('Receiving items from the network...') body = await self._connection.recv() except asyncio.TimeoutError: continue except asyncio.CancelledError: return except Exception as e: if isinstance(e, ConnectionError): __log__.info('Connection reset while receiving %s', e) elif isinstance(e, OSError): __log__.warning('OSError while receiving %s', e) else: __log__.exception('Unhandled exception while receiving') await asyncio.sleep(1) self._start_reconnect() break # TODO Check salt, session_id and sequence_number __log__.debug('Decoding packet of %d bytes...', len(body)) try: message = self.state.unpack_message(body) except (BrokenAuthKeyError, BufferError) as e: # The authorization key may be broken if a message was # sent malformed, or if the authkey truly is corrupted. # # There may be a buffer error if Telegram's response was too # short and hence not understood. Reset the authorization key # and try again in either case. # # TODO Is it possible to detect malformed messages vs # an actually broken authkey? __log__.warning('Broken authorization key?: {}'.format(e)) self.state.auth_key = None self._start_reconnect() break except SecurityError as e: # A step while decoding had the incorrect data. This message # should not be considered safe and it should be ignored. __log__.warning('Security error while unpacking a ' 'received message: {}'.format(e)) continue except TypeNotFoundError as e: # The payload inside the message was not a known TLObject. __log__.info('Server replied with an unknown type {:08x}: {!r}' .format(e.invalid_constructor_id, e.remaining)) continue except: __log__.exception('Unhandled exception while unpacking') await asyncio.sleep(1) else: try: await self._process_message(message) except asyncio.CancelledError: return except: __log__.exception('Unhandled exception while ' 'processing %s', message) await asyncio.sleep(1) # Response Handlers async def _process_message(self, message): """ Adds the given message to the list of messages that must be acknowledged and dispatches control to different ``_handle_*`` method based on its type. """ self._pending_ack.add(message.msg_id) handler = self._handlers.get(message.obj.CONSTRUCTOR_ID, self._handle_update) await handler(message) async def _handle_rpc_result(self, message): """ Handles the result for Remote Procedure Calls: rpc_result#f35c6d01 req_msg_id:long result:bytes = RpcResult; This is where the future results for sent requests are set. """ rpc_result = message.obj message = self._pending_messages.pop(rpc_result.req_msg_id, None) __log__.debug('Handling RPC result for message %d', rpc_result.req_msg_id) if rpc_result.error: error = rpc_message_to_error(rpc_result.error) self._send_queue.put_nowait(self.state.create_message( MsgsAck([message.msg_id]) )) if not message.future.cancelled(): message.future.set_exception(error) return elif message: # TODO Would be nice to avoid accessing a per-obj read_result # Instead have a variable that indicated how the result should # be read (an enum) and dispatch to read the result, mostly # always it's just a normal TLObject. with BinaryReader(rpc_result.body) as reader: result = message.obj.read_result(reader) if not message.future.cancelled(): message.future.set_result(result) return else: # TODO We should not get responses to things we never sent __log__.info('Received response without parent request: {}' .format(rpc_result.body)) async def _handle_container(self, message): """ Processes the inner messages of a container with many of them: msg_container#73f1f8dc messages:vector<%Message> = MessageContainer; """ __log__.debug('Handling container') for inner_message in message.obj.messages: await self._process_message(inner_message) async def _handle_gzip_packed(self, message): """ Unpacks the data from a gzipped object and processes it: gzip_packed#3072cfa1 packed_data:bytes = Object; """ __log__.debug('Handling gzipped data') with BinaryReader(message.obj.data) as reader: message.obj = reader.tgread_object() await self._process_message(message) async def _handle_update(self, message): __log__.debug('Handling update {}' .format(message.obj.__class__.__name__)) if self._update_callback: self._update_callback(message.obj) async def _handle_pong(self, message): """ Handles pong results, which don't come inside a ``rpc_result`` but are still sent through a request: pong#347773c5 msg_id:long ping_id:long = Pong; """ pong = message.obj __log__.debug('Handling pong for message %d', pong.msg_id) message = self._pending_messages.pop(pong.msg_id, None) if message: message.future.set_result(pong) async def _handle_bad_server_salt(self, message): """ Corrects the currently used server salt to use the right value before enqueuing the rejected message to be re-sent: bad_server_salt#edab447b bad_msg_id:long bad_msg_seqno:int error_code:int new_server_salt:long = BadMsgNotification; """ bad_salt = message.obj __log__.debug('Handling bad salt for message %d', bad_salt.bad_msg_id) self.state.salt = bad_salt.new_server_salt if self._last_ack and bad_salt.bad_msg_id == self._last_ack.msg_id: self._send_queue.put_nowait(self._last_ack) return try: self._send_queue.put_nowait( self._pending_messages[bad_salt.bad_msg_id]) except KeyError: # May be MsgsAck, those are not saved in pending messages __log__.info('Message %d not resent due to bad salt', bad_salt.bad_msg_id) async def _handle_bad_notification(self, message): """ Adjusts the current state to be correct based on the received bad message notification whenever possible: bad_msg_notification#a7eff811 bad_msg_id:long bad_msg_seqno:int error_code:int = BadMsgNotification; """ bad_msg = message.obj msg = self._pending_messages.get(bad_msg.bad_msg_id) __log__.debug('Handling bad msg for message %d', bad_msg.bad_msg_id) if bad_msg.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. to = self.state.update_time_offset(correct_msg_id=message.msg_id) __log__.info('System clock is wrong, set time offset to %ds', to) # Correct the msg_id *of the message to resend*, not all. # # If we correct them all, new "bad message" would not find # the old invalid IDs, causing all awaits to never finish. if msg: del self._pending_messages[msg.msg_id] self.state.update_message_id(msg) self._pending_messages[msg.msg_id] = msg elif bad_msg.error_code == 32: # msg_seqno too low, so just pump it up by some "large" amount # TODO A better fix would be to start with a new fresh session ID self.state._sequence += 64 elif bad_msg.error_code == 33: # msg_seqno too high never seems to happen but just in case self.state._sequence -= 16 else: if msg: del self._pending_messages[msg.msg_id] msg.future.set_exception(BadMessageError(bad_msg.error_code)) return # Messages are to be re-sent once we've corrected the issue if msg: self._send_queue.put_nowait(msg) else: # May be MsgsAck, those are not saved in pending messages __log__.info('Message %d not resent due to bad msg', bad_msg.bad_msg_id) async def _handle_detailed_info(self, message): """ Updates the current status with the received detailed information: msg_detailed_info#276d3ec6 msg_id:long answer_msg_id:long bytes:int status:int = MsgDetailedInfo; """ # TODO https://goo.gl/VvpCC6 msg_id = message.obj.answer_msg_id __log__.debug('Handling detailed info for message %d', msg_id) self._pending_ack.add(msg_id) async def _handle_new_detailed_info(self, message): """ Updates the current status with the received detailed information: msg_new_detailed_info#809db6df answer_msg_id:long bytes:int status:int = MsgDetailedInfo; """ # TODO https://goo.gl/G7DPsR msg_id = message.obj.answer_msg_id __log__.debug('Handling new detailed info for message %d', msg_id) self._pending_ack.add(msg_id) async def _handle_new_session_created(self, message): """ Updates the current status with the received session information: new_session_created#9ec20908 first_msg_id:long unique_id:long server_salt:long = NewSession; """ # TODO https://goo.gl/LMyN7A __log__.debug('Handling new session created') self.state.salt = message.obj.server_salt async def _handle_ack(self, message): """ Handles a server acknowledge about our messages. Normally these can be ignored except in the case of ``auth.logOut``: auth.logOut#5717da40 = Bool; Telegram doesn't seem to send its result so we need to confirm it manually. No other request is known to have this behaviour. Since the ID of sent messages consisting of a container is never returned (unless on a bad notification), this method also removes containers messages when any of their inner messages are acknowledged. """ ack = message.obj __log__.debug('Handling acknowledge for %s', str(ack.msg_ids)) if self._pending_containers: self._clean_containers(ack.msg_ids) for msg_id in ack.msg_ids: msg = self._pending_messages.get(msg_id, None) if msg and isinstance(msg.obj, LogOutRequest): del self._pending_messages[msg_id] msg.future.set_result(True) async def _handle_future_salts(self, message): """ Handles future salt results, which don't come inside a ``rpc_result`` but are still sent through a request: future_salts#ae500895 req_msg_id:long now:int salts:vector = FutureSalts; """ # TODO save these salts and automatically adjust to the # correct one whenever the salt in use expires. __log__.debug('Handling future salts for message %d', message.msg_id) msg = self._pending_messages.pop(message.msg_id, None) if msg: msg.future.set_result(message.obj) async def _handle_state_forgotten(self, message): """ Handles both :tl:`MsgsStateReq` and :tl:`MsgResendReq` by enqueuing a :tl:`MsgsStateInfo` to be sent at a later point. """ self.send(MsgsStateInfo(req_msg_id=message.msg_id, info=chr(1) * len(message.obj.msg_ids))) async def _handle_msg_all(self, message): """ Handles :tl:`MsgsAllInfo` by doing nothing (yet). """ class _ContainerQueue(asyncio.Queue): """ An asyncio queue that's aware of `MessageContainer` instances. The `get` method returns either a single `TLMessage` or a list of them that should be turned into a new `MessageContainer`. Instances of this class can be replaced with the simpler ``asyncio.Queue`` when needed for testing purposes, and a list won't be returned in said case. """ async def get(self): result = await super().get() if self.empty() or result == _reconnect_sentinel or\ isinstance(result.obj, MessageContainer): return result size = result.size() result = [result] while not self.empty(): item = self.get_nowait() if (item == _reconnect_sentinel or isinstance(item.obj, MessageContainer) or size + item.size() > MessageContainer.MAXIMUM_SIZE): self.put_nowait(item) break else: size += item.size() result.append(item) return result