83 lines
2.3 KiB
Python
83 lines
2.3 KiB
Python
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#!/usr/bin/env python3
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"""
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Send/receive UDP multicast packets.
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Requires that your OS kernel supports IP multicast.
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Usage:
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mcast -s (sender, IPv4)
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mcast -s -6 (sender, IPv6)
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mcast (receivers, IPv4)
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mcast -6 (receivers, IPv6)
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"""
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MYPORT = 8123
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MYGROUP_4 = '225.0.0.250'
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MYGROUP_6 = 'ff15:7079:7468:6f6e:6465:6d6f:6d63:6173'
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MYTTL = 1 # Increase to reach other networks
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import time
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import struct
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import socket
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import sys
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def main():
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group = MYGROUP_6 if "-6" in sys.argv[1:] else MYGROUP_4
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if "-s" in sys.argv[1:]:
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sender(group)
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else:
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receiver(group)
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def sender(group):
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addrinfo = socket.getaddrinfo(group, None)[0]
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s = socket.socket(addrinfo[0], socket.SOCK_DGRAM)
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# Set Time-to-live (optional)
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ttl_bin = struct.pack('@i', MYTTL)
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if addrinfo[0] == socket.AF_INET: # IPv4
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s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl_bin)
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else:
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s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, ttl_bin)
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while True:
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data = repr(time.time()).encode('utf-8') + b'\0'
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s.sendto(data, (addrinfo[4][0], MYPORT))
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time.sleep(1)
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def receiver(group):
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# Look up multicast group address in name server and find out IP version
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addrinfo = socket.getaddrinfo(group, None)[0]
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# Create a socket
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s = socket.socket(addrinfo[0], socket.SOCK_DGRAM)
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# Allow multiple copies of this program on one machine
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# (not strictly needed)
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s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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# Bind it to the port
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s.bind(('', MYPORT))
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group_bin = socket.inet_pton(addrinfo[0], addrinfo[4][0])
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# Join group
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if addrinfo[0] == socket.AF_INET: # IPv4
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mreq = group_bin + struct.pack('=I', socket.INADDR_ANY)
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s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
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else:
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mreq = group_bin + struct.pack('@I', 0)
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s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)
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# Loop, printing any data we receive
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while True:
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data, sender = s.recvfrom(1500)
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while data[-1:] == '\0': data = data[:-1] # Strip trailing \0's
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print(str(sender) + ' ' + repr(data))
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if __name__ == '__main__':
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main()
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