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A simple multicast sender/listener. Adapted from https://pymotw.com/3/socket/multicast.html to contain both the sender and the listener in the same script.
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| #!/usr/bin/env python | |
| import argparse | |
| import datetime | |
| import socket | |
| import struct | |
| import time | |
| def listener(args): | |
| multicast_group = args.address | |
| server_address = ("", args.port) | |
| # Create the socket | |
| sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) | |
| # Bind to the server address | |
| sock.bind(server_address) | |
| # Tell the operating system to add the socket to | |
| # the multicast group on all interfaces. | |
| group = socket.inet_aton(multicast_group) | |
| mreq = struct.pack("4sL", group, socket.INADDR_ANY) | |
| sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq) | |
| # Receive/respond loop | |
| while True: | |
| print("\nwaiting to receive message") | |
| data, address = sock.recvfrom(1024) | |
| print(f"received {len(data)} bytes from {address}") | |
| print(data) | |
| print(f"sending acknowledgement to {address}") | |
| sock.sendto(b"ack", address) | |
| def sender(args): | |
| message = datetime.datetime.today().isoformat() | |
| multicast_group = (args.address, args.port) | |
| # Create the datagram socket | |
| sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) | |
| # Set a timeout so the socket does not block | |
| # indefinitely when trying to receive data. | |
| sock.settimeout(0.2) | |
| # Set the time-to-live for messages to 1 so they do not | |
| # go past the local network segment. | |
| ttl = struct.pack("b", 1) | |
| sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl) | |
| try: | |
| # Send data to the multicast group | |
| print(f"sending {message}") | |
| sock.sendto(bytes(message, "utf-8"), multicast_group) | |
| # Look for responses from all recipients | |
| while True: | |
| print("waiting to receive") | |
| try: | |
| data, server = sock.recvfrom(16) | |
| except socket.timeout: | |
| print("timed out, no more responses") | |
| break | |
| else: | |
| print(f"received {data} from {server}") | |
| finally: | |
| print("closing socket") | |
| sock.close() | |
| if __name__ == "__main__": | |
| default_address = "224.3.29.71" | |
| default_port = 10000 | |
| parser = argparse.ArgumentParser( | |
| description="""A multicast sender/listener. | |
| Adapted from https://pymotw.com/3/socket/multicast.html | |
| to include both the listener and the sender in a single script.""" | |
| ) | |
| parser.add_argument( | |
| "-a", | |
| "--address", | |
| metavar="address", | |
| type=str, | |
| help="multicast address to connect to (default = {})".format(default_address), | |
| default=default_address, | |
| ) | |
| parser.add_argument( | |
| "-p", | |
| "--port", | |
| metavar="port", | |
| type=int, | |
| help="multicast port (default = {})".format(default_port), | |
| default=default_port, | |
| ) | |
| parser.add_argument( | |
| "-l", "--listen", help="listen to multicast traffic", action="store_true" | |
| ) | |
| parser.add_argument( | |
| "-s", "--send", help="send multicast traffic", action="store_true" | |
| ) | |
| args = parser.parse_args() | |
| if args.listen: | |
| listener(args) | |
| elif args.send: | |
| while True: | |
| sender(args) | |
| time.sleep(3.14) | |
| else: | |
| parser.print_help() |
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