Java MulticastSocket with datagram source defined

Question

I am trying to subscribe to a particular market data feed, distributed by multicast via FAST protocol. In Java, there is MulticastSocket and there is DatagramChannel supporting multicast.

The FAST protocol library I use, OpenFAST, accepts MulticastSocket instances to create endpoints, but it seems to be impossible to specify source IP address in its configuration, it binds to "any source", which doesn't work with this market data feed. It is possible (since Java 1.7) to create a DatagramChannel with source IP defined, like described here:

NetworkInterface interf = NetworkInterface.getByName("eth0");
InetAddress group = InetAddress.getByName("225.0.0.100");
InetAddress source = InetAddress.getByName("172.20.40.1");

DatagramChannel dc = DatagramChannel.open(ProtocolFamily.INET)
    .setOption(SocketOption.SO_REUSEADDR, true)
    .bind(new InetSocketAddress(5000))
    .setOption(SocketOption.IP_MULTICAST_IF, interf);

MembershipKey key = dc.join(group, interf, source); // <- source specified

However, I don't see a way to get a MulticastSocket from channel, the socket() method returns just the plain old DatagramSocket.

Is there a way to create a MulticastSocket with source filtering enabled, either directly or from DatagramChannel?

Answer 1

java.nio.MulticastChannel implements source-specific multicast, which is only available in IGMPv3. java.net.MulticastSocket, on the other hand, only supports IGMPv2, so you are out of luck here.

I would suggest you filter unneeded multicast sources out at the firewall level, but you can also try DatagramSocket.connect() to establish source filtering in the app.

Hope this helps.