def test_tcp_client():
port = random.randint(50000, 60000) # Arbitrary non-privileged port
run_server_echo_thread(port)
msg = b'Unit testing...'
client = TcpClient()
client.connect('localhost', port)
client.write(msg)
assert msg == client.read(
16), 'Read message does not equal sent message'
client.close()
class TcpTransport:
def __init__(self, ip_address, port):
self.tcp_client = TcpClient()
self.send_counter = 0
self.tcp_client.connect(ip_address, port)
# Original reference: https://core.telegram.org/mtproto#tcp-transport
# The packets are encoded as: total length, sequence number, packet and checksum (CRC32)
def send(self, packet):
"""Sends the given packet (bytes array) to the connected peer"""
if not self.tcp_client.connected:
raise ConnectionError('Client not connected to server.')
with BinaryWriter() as writer:
writer.write_int(len(packet) + 12) # 12 = size_of (integer) * 3
writer.write_int(self.send_counter)
writer.write(packet)
crc = crc32(writer.get_bytes())
writer.write_int(crc, signed=False)
self.send_counter += 1
self.tcp_client.write(writer.get_bytes())
def receive(self, timeout=timedelta(seconds=5)):
"""Receives a TCP message (tuple(sequence number, body)) from the connected peer.
There is a default timeout of 5 seconds before the operation is cancelled.
Timeout can be set to None for no timeout"""
# First read everything we need
packet_length_bytes = self.tcp_client.read(4, timeout)
packet_length = int.from_bytes(packet_length_bytes, byteorder='little')
seq_bytes = self.tcp_client.read(4, timeout)
seq = int.from_bytes(seq_bytes, byteorder='little')
body = self.tcp_client.read(packet_length - 12, timeout)
checksum = int.from_bytes(
self.tcp_client.read(4, timeout), byteorder='little', signed=False)
# Then perform the checks
rv = packet_length_bytes + seq_bytes + body
valid_checksum = crc32(rv)
if checksum != valid_checksum:
raise InvalidChecksumError(checksum, valid_checksum)
# If we passed the tests, we can then return a valid TCP message
return seq, body
def close(self):
if self.tcp_client.connected:
self.tcp_client.close()
def cancel_receive(self):
"""Cancels (stops) trying to receive from the
remote peer and raises a ReadCancelledError"""
self.tcp_client.cancel_read()
def get_client_delay(self):
"""Gets the client read delay"""
return self.tcp_client.delay