perl - How to detect when socket connection is lost?

Question

I have a script (I don't have the code example here at the moment but I used IO::Async) which connects to socket on a remote server and listens. Client usually just listens for new data.

Problem is that the client is not able to detect if network problems occur and the socket connection is gone. I used IO::Async and I also tried it with IO::Socket. Handle is always "connected" after the initial connection is established.

If the network connection is established again the socket connection is naturally still lost because the script has no idea that it should reconnect.

I was thinking to create some kind of "keepAlive" which "pings" (syswrite) the socket every X seconds (if nothing new came through socket) to check whether the connection is still there.

Is this the correct way to do it or is there maybe an another more creative or cleaner solution?

Answer 1

You can set the SO_KEEPALIVE socket option which, for TCP, sends periodic keepalive messages, and may help detect this condition. If this is detected, you will be delivered an EOF condition (most likely causing the containing IO::Async::Stream to fire on_read_eof).

For a better solution you might consider some sort of application-level keepalive message, such as IRC's PING command.