tcp-to-tls-proxy.js - A simple NodeJS proxy to forward a given unencrypted TCP connection to a TLS encrypted server

tcp-to-tls-proxy.js

/*
  tcp-to-tls-proxy.js - A simple NodeJS proxy to forward a given unencrypted TCP connection to a TLS encrypted server.
  by InvoxiPlayGames, hereby released into the public domain. Not that there's much to it to license.
  
  I created this as a way to connect to my modern, TLS 1.3-supporting XMPP server from iChat on a
  PowerBook running OS X Leopard (hence the default ports), but this can be used for anything that
  accepts a raw TLS connection where a legacy client can only handle an unencrypted connection.
  Please be safe with this, don't run this over an external network as it *is* reducing security.
  
  To use, replace the host and port in tls_settings with your target server, and host_port with
  the port number you wish to host the proxy on, then run "node tcp-to-tls-proxy.js". No dependencies!
*/

const net = require("net");
const tls = require("tls");

var tls_settings = {
    host: "target-hostname.lit",
    port: 5223
};
var host_port = 5222;

function connection_proxy(conn) {
    var remote_address = conn.remoteAddress + ':' + conn.remotePort;  
    var client = tls.connect(tls_settings, () => {
        console.log(`Client at ${remote_address} connected, and proxy established.`);
        conn.on('data', (data) => { client.write(data) });
        client.on('data', (data) => { conn.write(data) });
        conn.on('close', () => { console.log(`Client at ${remote_address} has dropped connection.`); client.end() });
        client.on('end', () => { console.log(`Server has dropped connection to ${remote_address}.`); conn.end(); });
    });
}

var server = net.createServer();    
server.on('connection', connection_proxy);
server.listen(host_port, () => {
    console.log(`Proxy listening on ${host_port} (target: ${tls_settings.host}:${tls_settings.port})`)
});