testproxy.js

#! /usr/bin/env node

/**
 testProxy 1.3.4
 Test your local websites on other devices
 @copyright 2023 Edwin Martin
 @license MIT
 */

const http = require('http');
const httpProxy = require('http-proxy');

const args = getArguments();

if (args.error) {
	printUsage(args.error);
} else {
	const url = startProxy(args.host, args.port, args.listenPort);

	if (args.qr) {
		showQR(url);
	}
}

//=== Function declarations ============

/**
 * Parse command line arguments
 */
function getArguments() {
	let opt = {};

	if (process.argv.length < 3) {
		return {error: "testProxy does not see enough arguments."};
	}

	process.argv.forEach(arg => {
		parseUrl(opt, arg);
		parseListenPort(opt, arg);
		parseQR(opt, arg);
	});

	return opt;

	//== functions

	function parseListenPort(opt, arg) {
		const match = arg.match(/-[lp] ?([0-9]+)/);

		if (match) {
			opt.listenPort = parseInt(match[1], 10);
		} else if (!opt.listenPort) {
			opt.listenPort = 0;
		}
	}

	function parseUrl(opt, url) {
		const match = url.match(/http(s?):\/\/([-a-z0-9.]+):?([0-9]+)?(\/.*)?/);

		if (match) {
			opt.host = match[2];
			opt.port = match[3] || 80;
			opt.path = match[4];
		}
	}

	function parseQR(opt, arg) {
		if (arg == '-noqr') {
			opt.qr = false;
		} else if (opt.qr == null) {
			opt.qr = true;
		}
	}
}


/**
 * Find ip addresses of local computer
 * @returns {Array} ip-addresses
 */
function getIpAddresses() {
	const os = require('os');
	const ifaces = os.networkInterfaces();

	return Object.keys(ifaces).reduce((prev, iface) =>
			prev.concat(ifaces[iface].filter(address =>
				!address.internal && address.family == 'IPv4'
			))
		, []);
}

/**
 * Start the actual proxy
 * @returns {String} (First) url
 */
function startProxy(hostname, port, listenPort) {
	const proxy = httpProxy.createProxyServer({});
	let returnUrl;

	proxy.on('proxyReq', proxyReq =>
		proxyReq.setHeader('Host', hostname)
	);

	const server = http.createServer((req, res) =>
		proxy.web(req, res, {
			target: `http://${hostname}:${port}`
		})
	);

	server.listen(listenPort);

	if (listenPort === 0) {
		listenPort = server.address().port;
	}

	getIpAddresses().forEach(ip => {
			const url = getUrl(ip.address, listenPort);
			returnUrl = returnUrl || url;
			console.log(`Listening on ${url}`);
		}
	);

	return returnUrl;
}

function printUsage(error) {
	console.error(`Oops. ${error}`);
	console.error("Usage: node testproxy <url> [-l<listen-port>] [-noqr]");
}

/**
 * Show QR code on the terminal
 * @param url
 */
function showQR(url) {
	const qrcode = require('qrcode-terminal');
	qrcode.generate(url);
}

/**
 * Build url from host, port and path
 * @param host
 * @param port
 * @param path
 */
function getUrl(host, port = 80, path = '/') {
	return `http://${host}:${port}${path}`;
}