Telethon/telethon/network/connection/connection.py
2019-05-03 21:38:41 +02:00

267 lines
8.2 KiB
Python

import abc
import asyncio
import socket
import ssl as ssl_mod
import sys
from ...errors import InvalidChecksumError
from ... import helpers
class Connection(abc.ABC):
"""
The `Connection` class is a wrapper around ``asyncio.open_connection``.
Subclasses will implement different transport modes as atomic operations,
which this class eases doing since the exposed interface simply puts and
gets complete data payloads to and from queues.
The only error that will raise from send and receive methods is
``ConnectionError``, which will raise when attempting to send if
the client is disconnected (includes remote disconnections).
"""
# this static attribute should be redefined by `Connection` subclasses and
# should be one of `PacketCodec` implementations
packet_codec = None
def __init__(self, ip, port, dc_id, *, loop, loggers, proxy=None):
self._ip = ip
self._port = port
self._dc_id = dc_id # only for MTProxy, it's an abstraction leak
self._loop = loop
self._log = loggers[__name__]
self._proxy = proxy
self._reader = None
self._writer = None
self._connected = False
self._send_task = None
self._recv_task = None
self._codec = None
self._obfuscation = None # TcpObfuscated and MTProxy
self._send_queue = asyncio.Queue(1)
self._recv_queue = asyncio.Queue(1)
async def _connect(self, timeout=None, ssl=None):
if not self._proxy:
self._reader, self._writer = await asyncio.wait_for(
asyncio.open_connection(
self._ip, self._port, loop=self._loop, ssl=ssl),
loop=self._loop, timeout=timeout
)
else:
import socks
if ':' in self._ip:
mode, address = socket.AF_INET6, (self._ip, self._port, 0, 0)
else:
mode, address = socket.AF_INET, (self._ip, self._port)
s = socks.socksocket(mode, socket.SOCK_STREAM)
if isinstance(self._proxy, dict):
s.set_proxy(**self._proxy)
else:
s.set_proxy(*self._proxy)
s.setblocking(False)
await asyncio.wait_for(
self._loop.sock_connect(s, address),
timeout=timeout,
loop=self._loop
)
if ssl:
s.settimeout(timeout)
s = ssl_mod.wrap_socket(
s,
do_handshake_on_connect=True,
ssl_version=ssl_mod.PROTOCOL_SSLv23,
ciphers='ADH-AES256-SHA'
)
s.setblocking(False)
self._reader, self._writer = \
await asyncio.open_connection(sock=s, loop=self._loop)
self._codec = self.packet_codec(self)
self._init_conn()
await self._writer.drain()
async def connect(self, timeout=None, ssl=None):
"""
Establishes a connection with the server.
"""
await self._connect(timeout=timeout, ssl=ssl)
self._connected = True
self._send_task = self._loop.create_task(self._send_loop())
self._recv_task = self._loop.create_task(self._recv_loop())
async def disconnect(self):
"""
Disconnects from the server, and clears
pending outgoing and incoming messages.
"""
self._connected = False
await helpers._cancel(
self._log,
send_task=self._send_task,
recv_task=self._recv_task
)
if self._writer:
self._writer.close()
if sys.version_info >= (3, 7):
await self._writer.wait_closed()
def send(self, data):
"""
Sends a packet of data through this connection mode.
This method returns a coroutine.
"""
if not self._connected:
raise ConnectionError('Not connected')
return self._send_queue.put(data)
async def recv(self):
"""
Receives a packet of data through this connection mode.
This method returns a coroutine.
"""
while self._connected:
result = await self._recv_queue.get()
if result: # None = sentinel value = keep trying
return result
raise ConnectionError('Not connected')
async def _send_loop(self):
"""
This loop is constantly popping items off the queue to send them.
"""
try:
while self._connected:
self._send(await self._send_queue.get())
await self._writer.drain()
except asyncio.CancelledError:
pass
except Exception as e:
if isinstance(e, IOError):
self._log.info('The server closed the connection while sending')
else:
self._log.exception('Unexpected exception in the send loop')
await self.disconnect()
async def _recv_loop(self):
"""
This loop is constantly putting items on the queue as they're read.
"""
while self._connected:
try:
data = await self._recv()
except asyncio.CancelledError:
break
except Exception as e:
if isinstance(e, (IOError, asyncio.IncompleteReadError)):
msg = 'The server closed the connection'
self._log.info(msg)
elif isinstance(e, InvalidChecksumError):
msg = 'The server response had an invalid checksum'
self._log.info(msg)
else:
msg = 'Unexpected exception in the receive loop'
self._log.exception(msg)
await self.disconnect()
# Add a sentinel value to unstuck recv
if self._recv_queue.empty():
self._recv_queue.put_nowait(None)
break
try:
await self._recv_queue.put(data)
except asyncio.CancelledError:
break
def _init_conn(self):
"""
This method will be called after `connect` is called.
After this method finishes, the writer will be drained.
Subclasses should make use of this if they need to send
data to Telegram to indicate which connection mode will
be used.
"""
if self._codec.tag:
self._writer.write(self._codec.tag)
def _send(self, data):
self._writer.write(self._codec.encode_packet(data))
async def _recv(self):
return await self._codec.read_packet(self._reader)
def __str__(self):
return '{}:{}/{}'.format(
self._ip, self._port,
self.__class__.__name__.replace('Connection', '')
)
class ObfuscatedConnection(Connection):
"""
Base class for "obfuscated" connections ("obfuscated2", "mtproto proxy")
"""
"""
This attribute should be redefined by subclasses
"""
obfuscated_io = None
def _init_conn(self):
self._obfuscation = self.obfuscated_io(self)
self._writer.write(self._obfuscation.header)
def _send(self, data):
self._obfuscation.write(self._codec.encode_packet(data))
async def _recv(self):
return await self._codec.read_packet(self._obfuscation)
class PacketCodec(abc.ABC):
"""
Base class for packet codecs
"""
"""
This attribute should be re-defined by subclass to define if some
"magic bytes" should be sent to server right after conection is made to
signal which protocol will be used
"""
tag = None
def __init__(self, connection):
"""
Codec is created when connection is just made.
"""
self._conn = connection
@abc.abstractmethod
def encode_packet(self, data):
"""
Encodes single packet and returns encoded bytes.
"""
raise NotImplementedError
@abc.abstractmethod
async def read_packet(self, reader):
"""
Reads single packet from `reader` object that should have
`readexactly(n)` method.
"""
raise NotImplementedError