Telethon/telethon/network/mtproto_sender.py
2017-01-19 15:54:28 +01:00

383 lines
15 KiB
Python
Executable File

import gzip
from datetime import timedelta
from threading import RLock, Thread
from time import sleep
import telethon.helpers as utils
from telethon.crypto import AES
from telethon.errors import *
from telethon.tl.all_tlobjects import tlobjects
from telethon.tl.types import MsgsAck
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 = False
self.updates_thread = Thread(
target=self.updates_thread_method, name='Updates thread')
self.updates_thread_running = False
self.updates_thread_receiving = False
# Determine whether the received acknowledge request confirm
# our requests or not. This is not desired until we initialize
# our connection, because it breaks things when we call InvokeWithLayer
# TODO There might be a better way to handle msgs_ack requests
self.ack_requests_confirm = False
def disconnect(self):
"""Disconnects and **stops all the running threads** if any"""
self.set_listen_for_updates(enabled=False)
self.transport.close()
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"""
first_handler = not self.on_update_handlers
self.on_update_handlers.append(handler)
# If this is the first added handler,
# we must start the thread to receive updates
if first_handler:
self.set_listen_for_updates(enabled=True)
def remove_update_handler(self, handler):
self.on_update_handlers.remove(handler)
# If there are no more update handlers, stop the thread
if not self.on_update_handlers:
self.set_listen_for_updates(False)
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(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:
self.transport.cancel_receive()
# Now only us can be using this method
with self.lock:
# Set the flag to true so the updates thread stops trying to receive
self.waiting_receive = True
# 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()
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:
# Don't stop trying to receive until we get the request we wanted
while not request.confirm_received:
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)
# We can now set the flag to False thus resuming the updates thread
self.waiting_receive = False
# 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 self.ack_requests_confirm and code == 0x62d6b459:
ack = reader.tgread_object()
if request and request.msg_id in ack.msg_ids:
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()
for handler in self.on_update_handlers:
handler(tlobject)
return False
def handle_pong(self, msg_id, sequence, reader, request):
reader.read_int(signed=False) # code
recv_msg_id = reader.read_long(signed=False)
if recv_msg_id == request.msg_id:
request.confirm_received = True
return False
def handle_container(self, msg_id, sequence, reader, request):
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()
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):
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):
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):
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())
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_'):
print('Should wait {}s. Sleeping until then.'.format(
error.additional_data))
sleep(error.additional_data)
elif error.message.startswith('PHONE_MIGRATE_'):
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.')
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)
def handle_gzip_packed(self, msg_id, sequence, reader, request):
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_listen_for_updates(self, enabled):
if enabled:
if not self.updates_thread_running:
self.updates_thread_running = True
self.updates_thread_receiving = False
self.updates_thread.start()
else:
self.updates_thread_running = False
if self.updates_thread_receiving:
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:
# Only try to receive updates if we're not waiting to receive a request
if not self.waiting_receive:
with self.lock:
try:
self.updates_thread_receiving = True
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)
except (ReadCancelledError, TimeoutError):
pass
self.updates_thread_receiving = False
# If we are here, it is because the read was cancelled
# Sleep a bit just to give enough time for the other thread
# to acquire the lock. No need to sleep if we're not running anymore
if self.updates_thread_running:
sleep(0.1)