"Invalid argument: setsockopt" in log when running as Windows service, JDK >8, IPv6 stack not present

[justparking]

When running as Windows service which has no IPv6 addressing, I've seen this in the log:

11-24 14:38:30.77 [org.nodel.discovery.NodelDiscoverer.172_16_90_20] 
Socket operation failed; this may occur during network topology transitions. 
Will retry / reinit regardless... 
msg:Invalid argument: setsockopt

This doesn't seem to happen with JDK 8, but I've seen it with 17 and 21.

And it does not happen when you run as a user.

Workaround:
Instruct the JVM to explicitly ignore IPv6 altogether using the JVM option -Djava.net.preferIPv4Stack=true

Service config looks like this:

(you should just need to Stop and Start service)

From my research, this can be fixed using an alternative way to initialise the network interface:

Quick brain dump plus AI hinted, as what part of NodelDiscoverer.java might look like.

MulticastSocket socket = new MulticastSocket(0);

// Find the Network Interface
NetworkInterface ni = NetworkInterface.getByInetAddress(_intf);
if (ni == null || !ni.supportsMulticast())
    // pre-checks should have already avoided this but just in-case
    throw new IOException("Interface not found or does not support multicast: " + _intf);

// This is the line that works reliably under Windows services
socket.setOption(StandardSocketOptions.IP_MULTICAST_IF, ni);
// or: socket.setNetworkInterface(ni);

socket.setSoTimeout(5 * 60000);
socket.setReuseAddress(true);
socket.setTimeToLive(TTL);

socket.joinGroup(new InetSocketAddress(Discovery.MDNS_GROUP, 5353), ni);
// (the two-parameter joinGroup is preferred on Windows anyway)

NetworkInterface ni = NetworkInterface.getByInetAddress(_intf);
socket.setOption(StandardSocketOptions.IP_MULTICAST_IF, ni);