Telethon/telethon/network/connection/tcpmtproxy.py
2019-03-10 03:26:24 +01:00

128 lines
4.2 KiB
Python

import hashlib
import os
from .connection import Connection
from .tcpabridged import AbridgedPacket
from .tcpintermediate import IntermediatePacket, RandomizedIntermediatePacket
from ...crypto import AESModeCTR
class TcpMTProxy(Connection):
"""
Connector which allows user to connect to the Telegram via proxy servers
commonly known as MTProxy.
Implemented very ugly due to the leaky abstractions in Telethon networking
classes that should be refactored later (TODO).
.. warning::
The support for MTProtoProxies class is **EXPERIMENTAL** and prone to
be changed. You shouldn't be using this class yet.
"""
packet_codec = None
@staticmethod
def address_info(proxy_info):
if proxy_info is None:
raise ValueError("No proxy info specified for MTProxy connection")
return proxy_info[:2]
def __init__(self, ip, port, dc_id, *, loop, loggers, proxy=None):
proxy_host, proxy_port = self.address_info(proxy)
super().__init__(
proxy_host, proxy_port, dc_id, loop=loop, loggers=loggers)
self._codec = self.packet_codec()
secret = bytes.fromhex(proxy[2])
is_dd = (len(secret) == 17) and (secret[0] == 0xDD)
if is_dd and (self.packet_codec != RandomizedIntermediatePacket):
raise ValueError(
"Only RandomizedIntermediate can be used with dd-secrets")
secret = secret[:-1] if is_dd else secret
if len(secret) != 16:
raise ValueError(
"MTProxy secret must be a hex-string representing 16 bytes")
self._dc_id = dc_id
self._secret = secret
def _init_conn(self):
self._obfuscation = MTProxyIO(self._reader, self._writer,
self._codec.mtproto_proxy_tag,
self._secret, self._dc_id)
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 ConnectionTcpMTProxyAbridged(TcpMTProxy):
"""
Connect to proxy using abridged protocol
"""
packet_codec = AbridgedPacket
class ConnectionTcpMTProxyIntermediate(TcpMTProxy):
"""
Connect to proxy using intermediate protocol
"""
packet_codec = IntermediatePacket
class ConnectionTcpMTProxyRandomizedIntermediate(TcpMTProxy):
"""
Connect to proxy using randomized intermediate protocol (dd-secrets)
"""
packet_codec = RandomizedIntermediatePacket
class MTProxyIO:
"""
It's very similar to tcpobfuscated.ObfuscatedIO, but the way
encryption keys, protocol tag and dc_id are encoded is different.
"""
header = None
def __init__(self, reader, writer, protocol_tag, secret, dc_id):
self._reader = reader
self._writer = writer
# Obfuscated messages secrets cannot start with any of these
keywords = (b'PVrG', b'GET ', b'POST', b'\xee\xee\xee\xee')
while True:
random = os.urandom(64)
if (random[0] != 0xef and
random[:4] not in keywords and
random[4:4] != b'\0\0\0\0'):
break
random = bytearray(random)
random_reversed = random[55:7:-1] # Reversed (8, len=48)
# Encryption has "continuous buffer" enabled
encrypt_key = hashlib.sha256(
bytes(random[8:40]) + secret).digest()
encrypt_iv = bytes(random[40:56])
decrypt_key = hashlib.sha256(
bytes(random_reversed[:32]) + secret).digest()
decrypt_iv = bytes(random_reversed[32:48])
self._aes_encrypt = AESModeCTR(encrypt_key, encrypt_iv)
self._aes_decrypt = AESModeCTR(decrypt_key, decrypt_iv)
random[56:60] = protocol_tag
dc_id_bytes = dc_id.to_bytes(2, "little", signed=True)
random = random[:60] + dc_id_bytes + random[62:]
random[56:64] = self._aes_encrypt.encrypt(bytes(random))[56:64]
self.header = random
async def readexactly(self, n):
return self._aes_decrypt.encrypt(await self._reader.readexactly(n))
def write(self, data):
self._writer.write(self._aes_encrypt.encrypt(data))