client6: Listen on all interfaces

client6.py

@@ -16,7 +16,12 @@ sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
 sock.bind(server_address)
 
 # on all interfaces.
-sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, socket.inet_pton(socket.AF_INET6, args.multicast_group) + struct.pack('@I', 0))
+for ifidx, ifname in socket.socket.if_nameindex():
+    print("joining %s @ [%d]%s" % (args.multicast_group, ifidx, ifname))
+    bifidx = struct.pack("@i", ifidx)
+    mreq = socket.inet_pton(socket.AF_INET6, args.multicast_group) + \
+            bifidx
+    sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)  # = IPV6_ADD_MEMBERSHIP
 
 try:
     while True: