how to tell when an underlying socket is closed, or how to force it closed

[timprepscius]

So I need to discover public ips & ports.

I would like to:
a. create a quic connection using a specific socket-port X to a server
b. server sends client, "this is your public IP and port"
c. client closes quic connection
d. close underlying socket completely / or detect when underlying socket is closed

e. create a new quic listener on the same port X

I'm thinking about FIN and FIN_WAIT.

If I:
case QUIC_CONNECTION_EVENT_SHUTDOWN_COMPLETE:
quic->ConnectionClose(Connection);

Is the socket closed at this point?

Can I close the socket and not wait for FIN/FIN_WAIT?

--

How do I know when the underlying socket has closed?

[nibanks]

I suggest you take a look at https://github.com/microsoft/msquic/tree/main/src/tools/ip. This does pretty much exactly what you want I think. I'm also had some serious thought of writing up an official QUIC extension to more fundamentally support this directly in the QUIC protocol. I'd be happy to discuss this topic more on Discord.

A while back, I did start writing up https://github.com/nibanks/quic-new-path which would use something like this to then allow you to explicitly change paths, which can be used for things like punching through NATs and going around VPN bottlenecks.

[timprepscius]

I was reading through the tools/ip code. I was hoping to do this without doing a whole:

    if (MsQuic) {
        if (Registration) {
            MsQuic->RegistrationClose(Registration);
        }
        MsQuicClose(MsQuic);
    }

Is there a way to wait for the socket close without MsQuicClose/RegistrationClose?
Is it closed asynchronously after the ConnectionClose?

I'll read through the quic-new-path now.

[nibanks]

ConnectionClose does close the socket. The RegistrationClose just cleans up everything else and waits for it.

[timprepscius]

Excellent.

Thanks