shadowtenpo/ccrelay.js

const net = require('net');
const dgram = require('dgram');

// Note: src and dst addresses in this file are full IP strings only.

function CCRelay(host) {
	console.info("Relay started for " + host);
	this.host = host;
	this.sockets = {};
	this.servers = {};
	this.onReceive = function(sport, dport, type, msg) {}
}

CCRelay.prototype.bindUDP = function(port) {
	if (this.sockets['udp'+port]) {
		console.warn('Attempted to bind more than once on '+this.host+':'+this.port);
		return this.sockets['udp'+port];
	}
	var socket = dgram.createSocket('udp4');
	socket.on('error', (e) => {
		console.error('udp '+this.host+':'+port+' error', e);
		socket.close();
		this.sockets['udp'+port] = null;
		this.bindUDP(port);
	});
	socket.on('message', (msg, rinfo) => {
		this.onReceive(rinfo.port, port, 'udp', msg);
	});
	var bindpromise = new Promise((resolve) => {
		socket.bind({address: this.host, port: port}, () => {
			this.sockets['udp'+port] = socket;
			resolve(socket);
		});
	});
	this.sockets['udp'+port] = bindpromise;
	return bindpromise;
};

CCRelay.prototype.sendUDP = function(dst, sport, dport, msg) {
	var socket = this.sockets['udp'+sport];
	if (!socket) {
		socket = this.bindUDP(sport);
	}
	if (socket instanceof Promise) {
		return socket.then(() => {
			return this.sendUDP(dst, sport, dport, msg);
		});
	}
	return new Promise((resolve) => {
		socket.send(msg, dport, dst, resolve);
	});
};

CCRelay.prototype._setupTCPSocket = function(socket, gameport, relayport) {
	socket.on('data', (msg) => {
		this.onReceive(gameport, relayport, 'tcp', msg);
	});
	socket.on('end', () => {
		if (this.sockets['tcp'+gameport+'-'+relayport]) {
			console.info('tcp'+gameport+'-'+relayport + ' fin\'ed');
			this.onReceive(gameport, relayport, 'tcpfin');
		}
	});
	socket.on('close', () => {
		if (this.sockets['tcp'+gameport+'-'+relayport]) {
			console.info('tcp'+gameport+'-'+relayport + ' closed');
			this.sockets['tcp'+gameport+'-'+relayport] = null;
			this.onReceive(gameport, relayport, 'tcpclose');
		}
	});
	socket.on('error', e => {
		if (this.sockets['tcp'+gameport+'-'+relayport]) {
			console.info('tcp'+gameport+'-'+relayport + 'error', e);
			this.sockets['tcp'+gameport+'-'+relayport] = null;
			this.onReceive(gameport, relayport, 'tcpclose');
		}
	});
}

CCRelay.prototype.listenTCP = function(port) {
	if (this.servers['tcp'+port]) {
		console.warn('Attempted to listen more than once on '+this.host+':'+this.port);
		return this.servers['tcp'+port];
	}
	var server = net.createServer();
	server.on('error', (e) => {
		console.error('tcpserver '+this.host+':'+port+' error', e);
		server.close();
		this.servers['tcp'+port] = null;
		this.listenTCP(port);
	});
	server.on('connection', (socket) => {
		console.info('tcp'+socket.remotePort+'-'+port + ' created by accept');
		this._setupTCPSocket(socket, socket.remotePort, port);
		this.sockets['tcp'+socket.remotePort+'-'+port] = socket;
	});
	var listenpromise = new Promise((resolve) => {
		server.listen({host: this.host, port: port}, () => {
			this.servers['tcp'+port] = server;
			resolve(server);
		});
	});
	this.servers['tcp'+port] = listenpromise;
	return listenpromise;
};

CCRelay.prototype.sendTCP = function(dst, sport, dport, msg) {
	var socket = this.sockets['tcp'+dport+'-'+sport];
	if (!socket) {
		socket = new Promise((resolve) => {
			console.info('tcp'+dport+'-'+sport + 'created by connect');
			var newsocket = new net.Socket();
			this._setupTCPSocket(newsocket, dport, sport);
			newsocket.connect({
				port: dport, host: dst,
				localPort: sport, localAddress: this.host
			}, () => {
				this.sockets['tcp'+dport+'-'+sport] = newsocket;
				resolve(newsocket);
			});
		});
		this.sockets['tcp'+dport+'-'+sport] = socket;
	}
	if (socket instanceof Promise) {
		return socket.then(() => {
			return this.sendTCP(dst, sport, dport, msg);
		});
	}
	return new Promise((resolve) => {
		socket.write(msg, null, resolve);
	});
};

CCRelay.prototype.endTCP = function(sport, dport) {
	var socket = this.sockets['tcp'+dport+'-'+sport];
	if (!socket) {
		console.warn('Requested to end nonexistent socket ' + 'tcp'+dport+'-'+sport);
		return;
	}
	console.info('FIN on' + 'tcp'+dport+'-'+sport);
	socket.end();
};

CCRelay.prototype.closeTCP = function(sport, dport) {
	var socket = this.sockets['tcp'+dport+'-'+sport];
	if (!socket) {
		console.warn('Requested to close nonexistent socket ' + 'tcp'+dport+'-'+sport);
		return;
	}
	this.sockets['tcp'+dport+'-'+sport] = null;
	console.info('Close on' + 'tcp'+dport+'-'+sport);
	socket.destroy();
};

module.exports = CCRelay;