Created
March 24, 2022 03:01
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Forward local port to an external port through a local network proxy
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| /** | |
| * Forward local port to an external port through a local network proxy | |
| * | |
| * @author Masoud Zohrabi <mdzzohrabi@gmail.com> | |
| */ | |
| let net = require('net'); | |
| let invariant = (expr, error) => { if (!expr) throw Error(error); }; | |
| let log = console.log.bind(console); | |
| function main() { | |
| let [nodePath, scriptPath, ...args] = process.argv; | |
| /** @type {{[name: string]: any}} */ | |
| let Options = {}; | |
| // Parse cli arguments | |
| args.forEach(arg => { | |
| let sub = 0; | |
| if (arg.startsWith('--')) sub = 2; | |
| else if (arg.startsWith('-')) sub = 1; | |
| let [name, value] = arg.substring(sub).split('='); | |
| Options[name] = value || true; | |
| }); | |
| let { proxy, dest, port } = { proxy: null, dest: null, port: 9090, ...Options }; | |
| if (!proxy || !dest || !port) { | |
| return log(`Usage: node forward --port=9090 --proxy=127.0.0.0:8000 --dest=192.168.1.1:1234`); | |
| } | |
| let [proxyHost, proxyPort] = proxy.split(':'); | |
| let [destHost, destPort = 80] = dest.split(':'); | |
| invariant(proxyHost && proxyPort, `Invalid proxy address (e.g: 127.0.0.0:9090)`); | |
| invariant(destHost && destPort, `Invalid destination address (e.g: 127.0.0.0:9090)`); | |
| // Start forwarding server | |
| net.createServer(async client => { | |
| /** @type {net.Socket} */ | |
| let proxy; | |
| let terminateSession = (err) => { | |
| if (err) log('Close client connection because of exception:', err); | |
| if (!client.destroyed) client.end(); | |
| if (proxy && !proxy.destroyed) proxy.end(); | |
| } | |
| // Client connected | |
| client.on('error', terminateSession); | |
| try { | |
| // Create tunnel to server | |
| proxy = await createConnectionThroughProxy(proxyHost, proxyPort, destHost, destPort); | |
| proxy.on('error', terminateSession); | |
| client.pipe(proxy); | |
| proxy.pipe(client); | |
| } catch (err) { | |
| terminateSession(err); | |
| } | |
| }).listen(Number(port), () => { | |
| log(`Listen to ${port} for new connection`) | |
| }); | |
| } | |
| /** | |
| * Connect to a target through proxy | |
| * @param {string} proxyHost | |
| * @param {number} proxyPort | |
| * @param {string} remoteHost | |
| * @param {number} remotePort | |
| * @param {any} request | |
| * @returns {Promise<net.Socket>} | |
| */ | |
| function createConnectionThroughProxy(proxyHost, proxyPort, remoteHost, remotePort, request = '') { | |
| return new Promise((resolve, reject) => { | |
| let connection = net.createConnection(proxyPort, proxyHost, () => { | |
| connection.write(`CONNECT ${remoteHost}:${remotePort} HTTP/1.1\n\n${request}`); | |
| connection.once('data', buffer => { | |
| if (buffer.toString().includes('Connection established')) resolve(connection); | |
| else reject(buffer.toString()); | |
| }); | |
| }); | |
| connection.on('error', reject); | |
| }); | |
| } | |
| main(); |
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