node.js tcp proxy

proxy.js

var net = require("net");

var Proxy = function() {
};
Proxy.to = function(dst_host, dst_port) {
	var proxy = new Proxy();
	proxy.dstHost = dst_host;
	proxy.dstPort = dst_port;
	proxy.mid = [];
	return proxy;
};

Proxy.prototype.use = function(fn) {
	this.mid.push(fn);
	return this;
}

Proxy.prototype._handle = function(buf, src, dst, out) {
	var evt = {
		"buf": buf,
		"src": src,
		"dst": dst,
		"out": out
	};
	var next = Proxy.nop;
	for(var i = this.mid.length - 1; i >= 0; i--) {
		next = this.mid[i].bind(this, evt, next);
	}
	next();
	return this;
};

Proxy.prototype.listen = function(port) {
	var self = this;
	this.server = net.createServer(function (sockA) {
		console.log("sockA " + sockA.address().address + ":" + sockA.address().port);
		var preb = [];
		sockA.on("data", pre = function(data) {
			preb.push(data);
		});
		var sockB = net.connect(self.dstPort, self.dstHost, function() {
			console.log("sockB " + sockB.address().address + ":" + sockB.address().port);
			sockA.removeListener("data", pre);
			while(preb.length) {
				self._handle(preb.shift(), sockA, sockB, true);
			}
			sockA.on("data", function(buf) {
				self._handle(buf, sockA, sockB, true);
			});
			sockB.on("data", function(buf) {
				self._handle(buf, sockB, sockA, false);
			});
			sockA.on("end", function() {
				console.log("sockA end");
				sockB.removeAllListeners();
				sockB.end();
			});
			sockB.on("end", function() {
				console.log("sockB end");
				sockA.removeAllListeners();
				sockA.end();
			});
		});
	});
	this.server.listen(port, function() {
		// hello I am listening
	});
	return this;
};

// built-in middlewares

Proxy.nop = function() {
};

Proxy.send = function(evt, next) {
	evt.dst.write(evt.buf);
	next();
};

Proxy.consoleLogMeta = function(evt, next) {
	console.log(
		(evt.out ? "\x1B[35m" : "\x1B[33m")
		+ evt.src.remoteAddress + ":" + evt.src.remotePort
		+ "  ——>  "
		+ evt.dst.remoteAddress + ":" + evt.dst.remotePort
		+ " —— " + evt.buf.length + " bytes"
		+ "\x1B[0m"
	);
	next();
};

Proxy.consoleLogString = function(evt, next) {
	console.log(evt.buf.toString());
	next();
};

Proxy.consoleLogBuffer = function(evt, next) {
	var i = 0;
	while(i + 16 < evt.buf.length) {
		console.log(evt.buf.slice(i, i + 16));
		i += 16;
	}
	if(i < evt.buf.length) console.log(evt.buf.slice(i));
	next();
};

Proxy.consoleLogSnippet = function(evt, next) {
	var str = evt.buf.toString();
	var i;
	var ellip = false;
	i = str.indexOf("\n"); if(i != -1) {
		str = str.substr(0, i);
		ellip = true;
	}
	i = str.indexOf("\r"); if(i != -1) {
		str = str.substr(0, i);
		ellip = true;
	}
	var rows = 80; //process.binding('stdio').getRows();
	if(str.length > rows) {
		str = str.substr(0, rows);
		ellip = true;
	}
	if(ellip) {
		str += "…";
	}
	console.log(str);
	next();
};

module.exports = Proxy;


/* Usage:

var Proxy = require("./lib/proxy");

Proxy.to("test.com", 80)
.use(Proxy.consoleLogMeta)
.use(Proxy.send)
.listen(8080);

*/

Hey Brandon, thanks for this proxy. It worked for me on node 0.6.8, but not on node 0.8.8. Trying to see if anything has changed in the net module, but thought of letting you know.

I added a revision that was newer, try that revision https://gist.github.com/brandon-lockaby/2020839/2692bec6c64f8aa85e51eb9401f0320bd62d0220