http+websockt reverser proxy

index.js

const URL = require('url')
const HTTP = require('http')
const QUERY = require('querystring')

const port = parseInt(process.argv[2]) || 8223
const server = HTTP.createServer().listen(port)

const target = URL.parse('http://locahost:8080')
const host = target.host

const modifyHeaders = headers => ({
    ...headers,
    host,
    origin: null,
})

const stringifyHeaders = headers => (
    QUERY.stringify(
        headers,
        '\r\n',
        ': ',
        { encodeURIComponent: _ => _ }
    )
)

const createProxyReq = (req) => (
    HTTP.request({
        ...URL.parse(target.resolve(req.url)),
        method: req.method,
        headers: modifyHeaders(req.headers),
    })
)

// http
server.on('request', (req, res) => {
    if (!req.url.startsWith('/')) return res.end('invalid')
    const proxyReq = createProxyReq(req)
        .on('response', proxyRes => {
            res.writeHead(proxyRes.statusCode, proxyRes.headers)
            proxyRes
                .pipe(res)
                .on('error', () => res.end())
        })
        .on('error', () => res.end())
    req
        .pipe(proxyReq)
        .on('error', () => res.end())
})

// websocket
server.on('upgrade', (req, socket, head) => {
    createProxyReq(req)
        .on('upgrade', (proxyRes, proxySocket, proxyHead) => {
            if ((head || {}).length) socket.unshift(head)
            if ((proxyHead || {}).length) proxySocket.unshift(proxyHead)
            socket.write(
                [
                    'HTTP/1.1 101 Switching Protocols',
                    stringifyHeaders(proxyRes.headers),
                    '',
                    '',
                ]
                    .join('\r\n')
            )
            proxySocket
                .pipe(socket)
                .on('error', () => socket.end())
            socket
                .pipe(proxySocket)
                .on('error', () => socket.end())
        })
        .on('error', () => socket.end())
        .end()
})

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