Telethon/telethon/network/connection/tcpmtproxy.py
2019-03-12 20:25:33 +01:00

128 lines
4.1 KiB
Python

import hashlib
import os
from .connection import ObfuscatedConnection
from .tcpabridged import AbridgedPacketCodec
from .tcpintermediate import (
IntermediatePacketCodec,
RandomizedIntermediatePacketCodec
)
from ...crypto import AESModeCTR
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, connection):
self._reader = connection._reader
self._writer = connection._writer
(self.header,
self._encrypt,
self._decrypt) = self.init_header(
connection._secret, connection._dc_id, connection.packet_codec)
def init_header(self, secret, dc_id, packet_codec):
# Validate
is_dd = (len(secret) == 17) and (secret[0] == 0xDD)
is_rand_codec = issubclass(
packet_codec, RandomizedIntermediatePacketCodec)
if is_dd and not is_rand_codec:
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")
# 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])
encryptor = AESModeCTR(encrypt_key, encrypt_iv)
decryptor = AESModeCTR(decrypt_key, decrypt_iv)
random[56:60] = packet_codec.obfuscate_tag
dc_id_bytes = dc_id.to_bytes(2, "little", signed=True)
random = random[:60] + dc_id_bytes + random[62:]
random[56:64] = encryptor.encrypt(bytes(random))[56:64]
return (random, encryptor, decryptor)
async def readexactly(self, n):
return self._decrypt.encrypt(await self._reader.readexactly(n))
def write(self, data):
self._writer.write(self._encrypt.encrypt(data))
class TcpMTProxy(ObfuscatedConnection):
"""
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 TcpMTProxy classes is **EXPERIMENTAL** and prone to
be changed. You shouldn't be using this class yet.
"""
packet_codec = None
obfuscated_io = MTProxyIO
@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):
# connect to proxy's host and port instead of telegram's ones
proxy_host, proxy_port = self.address_info(proxy)
self._secret = bytes.fromhex(proxy[2])
super().__init__(
proxy_host, proxy_port, dc_id, loop=loop, loggers=loggers)
class ConnectionTcpMTProxyAbridged(TcpMTProxy):
"""
Connect to proxy using abridged protocol
"""
packet_codec = AbridgedPacketCodec
class ConnectionTcpMTProxyIntermediate(TcpMTProxy):
"""
Connect to proxy using intermediate protocol
"""
packet_codec = IntermediatePacketCodec
class ConnectionTcpMTProxyRandomizedIntermediate(TcpMTProxy):
"""
Connect to proxy using randomized intermediate protocol (dd-secrets)
"""
packet_codec = RandomizedIntermediatePacketCodec