mirror of
https://github.com/LonamiWebs/Telethon.git
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68 lines
2.3 KiB
Python
Executable File
68 lines
2.3 KiB
Python
Executable File
from network import TcpClient
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from binascii import crc32
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from errors import *
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from utils import BinaryWriter
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class TcpTransport:
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def __init__(self, ip_address, port):
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self.tcp_client = TcpClient()
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self.send_counter = 0
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self.tcp_client.connect(ip_address, port)
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# Original reference: https://core.telegram.org/mtproto#tcp-transport
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# The packets are encoded as: total length, sequence number, packet and checksum (CRC32)
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def send(self, packet):
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"""Sends the given packet (bytes array) to the connected peer"""
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if not self.tcp_client.connected:
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raise ConnectionError('Client not connected to server.')
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with BinaryWriter() as writer:
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writer.write_int(len(packet) + 12) # 12 = size_of (integer) * 3
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writer.write_int(self.send_counter)
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writer.write(packet)
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crc = crc32(writer.get_bytes())
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writer.write_int(crc, signed=False)
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self.tcp_client.write(writer.get_bytes())
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self.send_counter += 1
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def receive(self):
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"""Receives a TCP message (tuple(sequence number, body)) from the connected peer"""
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# First read everything we need
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packet_length_bytes = self.tcp_client.read(4)
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packet_length = int.from_bytes(packet_length_bytes, byteorder='little')
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seq_bytes = self.tcp_client.read(4)
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seq = int.from_bytes(seq_bytes, byteorder='little')
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body = self.tcp_client.read(packet_length - 12)
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checksum = int.from_bytes(self.tcp_client.read(4), byteorder='little', signed=False)
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# Then perform the checks
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rv = packet_length_bytes + seq_bytes + body
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valid_checksum = crc32(rv)
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if checksum != valid_checksum:
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raise InvalidChecksumError(checksum, valid_checksum)
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# If we passed the tests, we can then return a valid TCP message
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return seq, body
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def close(self):
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if self.tcp_client.connected:
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self.tcp_client.close()
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def cancel_receive(self):
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"""Cancels (stops) trying to receive from the
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remote peer and raises a ReadCancelledError"""
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self.tcp_client.cancel_read()
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def get_client_delay(self):
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"""Gets the client read delay"""
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return self.tcp_client.delay
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