55 lines
2 KiB
Python
55 lines
2 KiB
Python
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#!/usr/bin/env python3
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"""
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A simple UDP echo server.
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"""
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import argparse
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import itertools
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import logging
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import socket
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logger = logging.getLogger(__name__)
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# the buffer for receiving incoming messages
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BUFFER_SIZE = 4096
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def receive_next(sock):
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"Repeatedly tries receiving on the given socket until some data comes in."
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logger.debug("Waiting to receive data...")
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while True:
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try:
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return sock.recvfrom(BUFFER_SIZE)
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except socket.timeout:
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logger.debug("No data received yet: retrying.")
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pass
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def receive_and_send_one(sock):
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"Waits for a single datagram over the socket and echoes it back."
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input_data, addr = receive_next(sock)
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message = input_data.decode()
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logger.info("Received message from %s: %s (%s bytes).", addr, message, len(input_data))
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output_len = sock.sendto(input_data, addr)
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logger.info("Echoed message back to %s: %s (%s bytes).", addr, message, output_len)
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def start(args):
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"Runs the server."
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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sock.settimeout(5) # seconds
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sock.bind((args.host, args.port))
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logger.info("Listening on %s:%s.", args.host, args.port)
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try:
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for i in itertools.count(1):
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receive_and_send_one(sock)
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finally:
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logger.info("Shutting down.")
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sock.close()
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
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parser.add_argument('--host', help='The host that the server socket should bind to.', default="0.0.0.0")
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parser.add_argument('--port', help='The port that the server socket should bind to.', type=int, default=123)
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parser.add_argument('--verbose', '-v', help="Increases the logging verbosity level.", action='count')
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args = parser.parse_args()
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logging.basicConfig(level=logging.DEBUG if args.verbose else logging.INFO,
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format='%(asctime)s %(levelname)s %(message)s')
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start(args)
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