mirror of
https://github.com/LonamiWebs/Telethon.git
synced 2025-10-30 23:47:33 +03:00
44 lines
1.3 KiB
Python
44 lines
1.3 KiB
Python
import struct
|
|
from zlib import crc32
|
|
|
|
from .connection import Connection, PacketCodec
|
|
from ...errors import InvalidChecksumError
|
|
|
|
|
|
class FullPacketCodec(PacketCodec):
|
|
tag = None
|
|
|
|
def __init__(self, connection):
|
|
super().__init__(connection)
|
|
self._send_counter = 0 # Important or Telegram won't reply
|
|
|
|
def encode_packet(self, data):
|
|
# https://core.telegram.org/mtproto#tcp-transport
|
|
# total length, sequence number, packet and checksum (CRC32)
|
|
length = len(data) + 12
|
|
data = struct.pack('<ii', length, self._send_counter) + data
|
|
crc = struct.pack('<I', crc32(data))
|
|
self._send_counter += 1
|
|
return data + crc
|
|
|
|
async def read_packet(self, reader):
|
|
packet_len_seq = await reader.readexactly(8) # 4 and 4
|
|
packet_len, seq = struct.unpack('<ii', packet_len_seq)
|
|
body = await reader.readexactly(packet_len - 8)
|
|
checksum = struct.unpack('<I', body[-4:])[0]
|
|
body = body[:-4]
|
|
|
|
valid_checksum = crc32(packet_len_seq + body)
|
|
if checksum != valid_checksum:
|
|
raise InvalidChecksumError(checksum, valid_checksum)
|
|
|
|
return body
|
|
|
|
|
|
class ConnectionTcpFull(Connection):
|
|
"""
|
|
Default Telegram mode. Sends 12 additional bytes and
|
|
needs to calculate the CRC value of the packet itself.
|
|
"""
|
|
packet_codec = FullPacketCodec
|