Telethon/telethon/network/connection/tcpintermediate.py
2019-03-12 01:12:55 +01:00

47 lines
1.3 KiB
Python

import struct
import random
import os
from .connection import Connection, PacketCodec
class IntermediatePacketCodec(PacketCodec):
tag = b'\xee\xee\xee\xee'
obfuscate_tag = tag
def encode_packet(self, data):
return struct.pack('<i', len(data)) + data
async def read_packet(self, reader):
length = struct.unpack('<i', await reader.readexactly(4))[0]
return await reader.readexactly(length)
class RandomizedIntermediatePacketCodec(IntermediatePacketCodec):
"""
Data packets are aligned to 4bytes. This codec adds random bytes of size
from 0 to 3 bytes, which are ignored by decoder.
"""
tag = None
obfuscate_tag = b'\xdd\xdd\xdd\xdd'
def encode_packet(self, data):
pad_size = random.randint(0, 3)
padding = os.urandom(pad_size)
return super().encode_packet(data + padding)
async def read_packet(self, reader):
packet_with_padding = await super().read_packet(reader)
pad_size = len(packet_with_padding) % 4
if pad_size > 0:
return packet_with_padding[:-pad_size]
return packet_with_padding
class ConnectionTcpIntermediate(Connection):
"""
Intermediate mode between `ConnectionTcpFull` and `ConnectionTcpAbridged`.
Always sends 4 extra bytes for the packet length.
"""
packet_codec = IntermediatePacketCodec