HTTP/HTTPS Proxy server

https.js

const net = require('net');

const server = net.createServer();
const PORT = 9000;

// Emitted when an error occurs. The 'close' event will be called directly following this event.
server.on('error', (err) => {
	console.log('Error');
	console.log(err);
});

// Emitted when the server closes. Note that if connections exist, this event is not emitted until all the connections are ended.
server.on('close', () => {
	console.log('Closing client request');
});

// Emitted when a new connection is made. Socket object, the connection object is available to event handler. Socket is an instance of net.Socket.
server.on("connection", (clientListenerSocket) => {
	// Client connected to proxy
	let targetPort = 80, targetAddr;
	let isTLSConnection = false;

	clientListenerSocket.on('error', err => {
		console.log('CLIENT TO PROXY ERROR -> ', targetAddr);
		console.log(err);
	});

	clientListenerSocket.on('close', () => {
		console.log('Connection closed from client -> ', targetAddr);
	});

	// We will only need the first packet data to get the host details.
	clientListenerSocket.once('data', (data) => {
		isTLSConnection = data.toString().indexOf('CONNECT') !== -1;

		if (isTLSConnection) {
			// HTTPS
			targetPort = 443;
			targetAddr = data.toString().split('CONNECT ')[1].split(' ')[0].split(':')[0];
			console.log(targetAddr);
		}
		else {
			// HTTP
			console.log('*******************', data.toString())
			targetAddr = data.toString().split('Host: ')[1].split('\r\n')[0];
		}

		clientListenerSocket.on('data', (chunk) => {
			// console.log("c2p --->",chunk.toString('utf8'));
			proxyListenerSocket.write(chunk);
		});
		let proxyListenerSocket = net.createConnection({
			host: targetAddr,
			port: targetPort
		});

		proxyListenerSocket.on("connect", () => {
			if (isTLSConnection) {
				//Send Back OK to HTTPS CONNECT Request
				clientListenerSocket.write('HTTP/1.1 200 OK\r\n\n');
			} else {
				proxyListenerSocket.write(data);
			}
		});
		proxyListenerSocket.on("data", (chunk) => {
			// console.log("p2s --->",chunk.toString('utf8'));
			clientListenerSocket.write(chunk);
		})

		proxyListenerSocket.on("error", (err) => {
			console.log('PROXY TO SERVER ERROR');
			console.log(err);
		});
		proxyListenerSocket.on('end', () => {
			console.log('Connection end from proxy -> ', targetAddr);
		});
	});
});

server.listen(PORT, () => console.log(`Proxy server running on ${PORT}`));