Node.js: Client Disconnects from Server even with allowHalfOpen set to True

Question

I am trying to make a simple Node.js script which creates a server if the assigned port is not used, or connects to the server if the port is being used. I am using a recursive approach to this (using this link as reference), so I am running the same .js file on two different cmd windows.

The problem is that whenever the client connects to the server, it automatically goes into the 'end' listener, and I don't know why. After reading the docs, I found out about the allowHalfOpen property, of which the following is said in the API:

If allowHalfOpen is true, then the socket won't automatically send a FIN packet when the other end of the socket sends a FIN packet.

I thought this was the obvious solution, so I set the property to true on the server, but that didn't work either.

Here is the code:

var net = require('net');

var PORT_NUMBER = 1337;

connectToPort = function(connection) {
    if(connection === "server") { // Connect as server to the port.
        connectAsServer();
    } else if (connection == "client") { // Connect as client to the port.
        connectAsClient();
    } else {
        console.log("Incorrect Type Of Connection Passed.");
    }
}

connectAsServer = function() {
    // Attempt to create server.
    var server = net.createServer({allowHalfOpen:true}, function (socket) {
        socket.allowHalfOpen = true;

        socket.write('Hello from Server\r\n');
        socket.end("hello");
        console.log("someone went into server.");
        socket.pipe(socket);
    });

    console.log("Trying to Open Port " + PORT_NUMBER);

    server.listen(PORT_NUMBER, function() {
        console.log("\nServer 2 is now the official server. \n");
    });

    server.on('error', function(err) {
        console.log("error is " + err.code);
        if(err.code == 'EADDRINUSE') {
            console.log('Port is in use, becoming client...');
            setTimeout(function () {
              server.close();
              connectToPort("client");
            }, 1000);
        }
        if(err.code == 'ECONNRESET') {
            console.log("connection reset error.");
        }
    });

    server.on('end', function() {
        console.log("server 2 disconnected from port");
    });
}

connectAsClient = function() {

    var client = net.connect({port: PORT_NUMBER}, function() { //'connect' listener
      console.log('THIS IS CLIENT connected to server!');
    });

    client.on('data', function(data) {
      console.log(data.toString());
      client.write('hello world! from client!!\r\n');
    });

    client.on('end', function() {
        // client automatically goes here. 
        console.log('disconnected from server');
    });

    client.on('error', function(err) {
        console.log("there was an error in the client and the error is: " + err.code);
    });
}

connectToPort("server");

And here are the outputs from the console:

For the Server:

For the Client:

What I want essentially is to have the client disconnect only when the server closes or when some other event occurs. But ideally I want it to be connected to the server for exchange of data between them.

Is there something I am doing wrong? Why is the FIN package still sent even when allowHalfOpen is true on the Server?

Thanks,

Answer 1

I saw my mistake, I had the following line:

socket.end("hello");

Inside the server code, which essentially killed the client anyway.