slow TCP proxy

sockolepsy.js

/**
 * Usage: node sockolepsy.js <listen> <forward> <delay>
 *
 * Creates a generic TCP proxy that can introduce a controllable degree of
 * delay per packet.
 *
 * Params:
 *   listen - the port to listen on.
 *   forward - the port to foward to.
 *   delay - the amount of delay to introduce, in ms.
 *
 * For example, to create a proxy to MySQL with 50 milliseconds of delay, you
 * could run:
 *
 *   node sockolepsy.js 9999 3306 500
 *
 * Then connect your MySQL client to port 9999:
 *
 *   mysql -P9999
 *
 */
var net = require('net'),
    sys = require('sys');

var listen = 9999,
    forward = 3306,
    delay = 500,
    server;

if (process.argv.length < 5) {
    sys.puts('Usage: node ' + process.argv[1] + ' <listen> <forward> <delay>');
    process.exit(1);
}

listen = process.argv[2];
forward = process.argv[3];
delay = process.argv[4];

server = net.createServer(function(stream) {
    var client;
    stream.on('connect', function() {
        sys.puts('incoming connection');
        client = net.createConnection(forward);
        client.on('connect', function() {
            sys.puts('connected through');
        });
        client.on('data', function(data) {
            setTimeout(function() {
                stream.write(data);
            }, delay);
        });
    });
    stream.on('data', function(data) {
        client.write(data);
    });
    stream.on('end', function() {
        client.end();
        stream.end();
    })
});

server.listen(listen);