Telethon/telethon/_network/transports/full.py
Lonami Exo f5f0c84553 Completely overhaul connections and transports
Reduce abstraction leaks. Now the transport can hold any state,
rather than just the tag. It's also responsible to initialize on
the first connection, and they can be cleanly reset.

asyncio connections are no longer used, in favour of raw sockets,
which should avoid some annoyances.

For the time being, more obscure transport modes have been removed,
as well as proxy support, until further cleaning is done.
2022-01-15 13:33:50 +01:00

42 lines
1.2 KiB
Python

from .transport import Transport
import struct
from zlib import crc32
class Full(Transport):
def __init__(self):
self._send_counter = 0
self._recv_counter = 0
def recreate_fresh(self):
return type(self)()
def pack(self, input: bytes) -> bytes:
# https://core.telegram.org/mtproto#tcp-transport
length = len(input) + 12
data = struct.pack('<ii', length, self._send_counter) + input
crc = struct.pack('<I', crc32(data))
self._send_counter += 1
return data + crc
def unpack(self, input: bytes) -> (int, bytes):
if len(input) < 12:
raise EOFError()
length, seq = struct.unpack('<ii', input[:8])
if len(input) < length:
raise EOFError()
if seq != self._recv_counter:
raise ValueError(f'expected sequence value {self._recv_counter!r}, got {seq!r}')
body = input[8:length - 4]
checksum = struct.unpack('<I', input[length - 4:length])[0]
valid_checksum = crc32(input[:length - 4])
if checksum != valid_checksum:
raise InvalidChecksumError(checksum, valid_checksum)
self._recv_counter += 1
return length, body