index.js

const http = require("http");
const port = process.env.PORT || 9191;
const net = require("net");
const url = require("url");

const requestHandler = (req, res) => {
  // discard all request to proxy server except HTTP/1.1 CONNECT method
  res.writeHead(405, { "Content-Type": "text/plain" });
  res.end("Method not allowed");
};

const server = http.createServer(requestHandler);

const listener = server.listen(port, (err) => {
  if (err) {
    return console.error(err);
  }
  const info = listener.address();
  console.log(
    `Server is listening on address ${info.address} port ${info.port}`
  );
});

server.on("connect", (req, clientSocket, head) => {
  // listen only for HTTP/1.1 CONNECT method
  console.log(
    clientSocket.remoteAddress,
    clientSocket.remotePort,
    req.method,
    req.url
  );
  //   req.url.indexOf("youtube")
  if (!req.headers["proxy-authorization"]) {
    // here you can add check for any username/password, I just check that this header must exist!
    clientSocket.write(
      [
        "HTTP/1.1 407 Proxy Authentication Required",
        'Proxy-Authenticate: Basic realm="proxy"',
        "Proxy-Connection: close",
      ].join("\r\n")
    );
    clientSocket.end("\r\n\r\n"); // empty body
    return;
  }
  const { port, hostname } = url.parse(`//${req.url}`, false, true); // extract destination host and port from CONNECT request
  if (hostname && port) {
    const serverErrorHandler = (err) => {
      console.error(err.message);
      if (clientSocket) {
        clientSocket.end(`HTTP/1.1 500 ${err.message}\r\n`);
      }
    };
    const serverEndHandler = () => {
      if (clientSocket) {
        clientSocket.end(`HTTP/1.1 500 External Server End\r\n`);
      }
    };
    const serverSocket = net.connect(port, hostname); // connect to destination host and port
    const clientErrorHandler = (err) => {
      console.error(err.message);
      if (serverSocket) {
        serverSocket.end();
      }
    };
    const clientEndHandler = () => {
      if (serverSocket) {
        serverSocket.end();
      }
    };
    clientSocket.on("error", clientErrorHandler);
    clientSocket.on("end", clientEndHandler);
    serverSocket.on("error", serverErrorHandler);
    serverSocket.on("end", serverEndHandler);
    serverSocket.on("connect", () => {
      clientSocket.write(
        ["HTTP/1.1 200 Connection Established", "Proxy-agent: Node-VPN"].join(
          "\r\n"
        )
      );
      clientSocket.write("\r\n\r\n"); // empty body
      // "blindly" (for performance) pipe client socket and destination socket between each other
      serverSocket.pipe(clientSocket, { end: false });
      clientSocket.pipe(serverSocket, { end: false });
    });
  } else {
    clientSocket.end("HTTP/1.1 400 Bad Request\r\n");
    clientSocket.destroy();
  }
});