Stops working on connection change about kcptun-android

[madeye]

Set autoexpire to 10 and try again. It's expected, as kcptun cannot detect network changing correctly.

[Mygod]

Hmm yeah I guess I forgot to merge that change. I noticed that autoexpire was set to 60 though.

Is there a less hacky way to do this? I feel like the system should notify the clients when a UDP connection is shut down.

[madeye]

One possible solution is send a signal to kcptun process, e.g SIGUSR1 when we detected a network change.

[Mygod]

kcptun does check for connection closes, e.g. here. Maybe we should investigate why that isn't working.

[Mygod]

Upon further inspection, this issue seems to only occur in VPN mode. Proxy only mode does not have the same issue. Maybe another Dial call we missed perhaps?

Never mind. It seems like proxy mode also has this problem.

[Mygod]

Okay. It turns out the problem was caused by bindSocket. If we change it back to protect, everything will be fine.

[Mygod]

Okay after a lot of digging around, I might have to agree with you about sending a signal. I also created an issue at upstream since they also have similar issue there: xtaci/kcptun#642 But at this point, we might as well just use QUIC, where there is connection migration, honestly. So let's just say autoexpire is good enough for now.

Also I'm seeing SetDSCP: invalid connection on this build. Thoughts?

[madeye]

I saw SetDSCP: invalid connection as well. Not sure if it's an Android specific issue that we cannot set DSCP on that socket.

But it'd not be a problem, since most of NAT devices would just ignore and drop DSCP.