recv_multicast.py

#!/usr/bin/env python3
import socket
import sys
import struct

if len(sys.argv) != 2:
    print("usage: {} intf".format(sys.argv[0]))
    print("interfaces:")
    for idx, name in socket.if_nameindex():
        print("{}: {}".format(idx, name))
    sys.exit(1)

sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 1)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(('', 4242)) # bind all interfaces
group_addr = "ff02::4242:4242"
intf_index = socket.if_nametoindex(sys.argv[1])
mreq = struct.pack("=16si", socket.inet_pton(socket.AF_INET6, group_addr), intf_index)
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)
while True:
    data, sender = sock.recvfrom(1500) # 1500 = max size
    print("msg: {}".format(data))