CODEWITHSUNDEEP
node.js
erik.brannstrom
erik.brannstrom

Reputation: 123

Unable to override net.Socket.write

I can't seem to override net.Socket.write. The example below is not my real use case, but rather a scaled down, runnable example to demonstrate the issue.

const net = require("net");

class UTF8Socket extends net.Socket {
    constructor () {
        super();
        this.setEncoding("utf8");
    }

    write(data, cb) {
        console.log("Sending...");
        super.write(data, "utf8", cb);
    }

    end(data) {
        console.log("Ending socket...");
        super.end(data);
    }
}

// Setup server
const server = net.createServer(socket => {
    socket.setEncoding("utf8");
    socket.on("data", (res) => console.log("Server received data:", res));
});
server.listen(8080, '127.0.0.1');

// Create a UTF8Socket and write to server
const socket = new UTF8Socket();
socket.connect(8080, "127.0.0.1", () => {
    socket.write("test write\n");
    socket.end("test end");
});

Expected output:

Sending...

Ending socket...

Server received data: test write

test end

Actual output:

Ending socket...

Server received data: test write

test end

The overridden end function is called as you can see from the output, but only the original net.Socket.write is ever called. I feel like I'm missing something...

Upvotes: 0

Views: 440

Answers (1)

robertklep
robertklep

Reputation: 203474

I guess it's because of this code in the implementation of net.Socket.connect():

if (this.write !== Socket.prototype.write)
  this.write = Socket.prototype.write;

Possible workaround:

connect() {
  let result = super.connect.apply(this, arguments);
  this.write = UTF8Socket.prototype.write.bind(this);
  return result;
}

Upvotes: 2

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