SocketException: Connection reset by peer (OS Error: Connection reset by peer)

[leeflix]

I am using websockets in my dart application. My server occasionally crashes when a "peer resets the connection". I think its odd that an exception crashes the program. Is there any way to handle this?

[mraleph]

You would need to post a reproduction etc. Without code we could debug this is unactionable.

[leeflix]

@mraleph I am not doing anything fancy basically everything i do boils down to this:

    // start listening for ws connections there is no problem here
    
    SecurityContext? securityContext;
    var server;
    if (Env.certificateChainPath != null && Env.privateKeyPath != null) {
      securityContext = SecurityContext()
        ..usePrivateKeyBytes(File(Env.privateKeyPath!).readAsBytesSync())
        ..useCertificateChainBytes(File(Env.certificateChainPath!).readAsBytesSync());
      server = await HttpServer.bindSecure(Env.local ? "localhost" : InternetAddress.anyIPv6, Env.wsPort, securityContext);
    } else {
      server = await HttpServer.bind(Env.local ? "localhost" : InternetAddress.anyIPv6, Env.wsPort);
    }

    // the problem should be after here

    await for (var request in server) {
        if (WebSocketTransformer.isUpgradeRequest(request)) {
          WebSocket ws = await WebSocketTransformer.upgrade(request);
          ws.add(...); // send data
        }
    }

[leeflix]

I don't know where the error exactly occurs:

[leeflix]

can someone tell me a way to handle this exception?

[leeflix]

please help @mraleph i just need someone to tell me how to handle exceptions which are thrown in the lifecycle of the websocket

[mraleph]

@leeflix The challenge I am having here is that we need a way to reproduce this. Without reproduction it is hard to say what and where exactly is going wrong. I have tried some variations of trying to connect to WS server and then abruptly close connections - but I was not able to reproduce this sort of crash.

If this was a raw socket API, then I could just say that the code is using Socket.add and not catching errors from Socket.done / Socket.flush. But with HTTP/WebSockets these errors are handled internally.

So we really need a repro to be able to fix this.

[leeflix]

@mraleph any ideas why it says "SocketException" and not "WebSocketException". does that not indicate that the error is not caught on the Socket API level? also any ideas where this string "Connection reset by peer" comes from?