udp_listener.py

#!/usr/bin/env python
################################################################################
# The MIT License (MIT)
#
# Copyright (c) 2021 Mark LaPerriere
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
################################################################################
"""
Simple UDP server that prints out messages it receives.

Requires: Python3.6+
"""
import atexit
import argparse
import socket
import sys
from typing import Any, Callable, Tuple

DEFAULT_BUFSIZE = 1024

def cli() -> argparse.Namespace:
    parser = argparse.ArgumentParser('UDP Server - prints out data received')
    parser.add_argument(dest='ip', help='ip address to listen on')
    parser.add_argument(dest='port', type=int, help='UDP port to listen on')
    return parser.parse_args()


def setup_socket(ip: str, port: int) -> socket.socket:
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.bind((ip, port))
    atexit.register(sock.close)
    return sock


def listen(sock: socket.socket, data_handler: Callable, bufsize: int = DEFAULT_BUFSIZE):
    while True:
        try:
            data, addr = sock.recvfrom(bufsize)
        except (SystemExit, KeyboardInterrupt):
            break
        data_handler(data, addr)


def print_addr_and_data(data: Any, addr: Tuple[str, int]):
    print(f'[{addr}] {data}')


def main(args) -> int:
    print(f'Listening for UDP messages on {args.ip}:{args.port}...\n')
    sock = setup_socket(args.ip, args.port)
    listen(sock, print_addr_and_data)
    print('\nClosing up shop...')
    return 0

if __name__ == '__main__':
    sys.exit(main(cli()))