Simple Proxy Server

simple.js

const net = require('net')
const http = require('http')
const parse = require('url').parse
const port = parseInt(process.argv[2]) || 8080
const server = http.createServer().listen(port)

// MITM Mode
server.on('request', (req, res) => {
	if (!req.url.startsWith('http://')) return res.end('invalid')
	const url = parse(req.url)
	console.log('MITM', '>', url.hostname)
	req.pipe(
		http.request(Object.assign(url, { method: req.method, headers: req.headers }))
		.on('response', proxyRes => {
			res.writeHead(proxyRes.statusCode, proxyRes.headers)
			proxyRes.pipe(res)
		})
		.on('error', () => res.end())
	)
})

// Tunnel Mode
server.on('connect', (req, socket, head) => {
	const url = parse('https://' + req.url)
	console.log('TUNNEL', '>', url.hostname)
	const proxySocket = net.connect(url.port, url.hostname)
	.on('connect', () => {
		socket.write('HTTP/1.1 200 Connection established\r\n\r\n')
		proxySocket.write(head)
		proxySocket.pipe(socket)
		socket.pipe(proxySocket)
	})
	.on('error', () => socket.end())
	socket.on('error', () => socket.end())
})

console.log(`HTTP Server running @ http://0.0.0.0:${port}`)