index.js

import express from 'express'
import morgan from 'morgan'

const app = express()

app.use(morgan('combined'))
app.use(express.raw({ type: '*/*' }))

app.all(/.*/, (req, res) => {
	let header = `${req.method} ${req.originalUrl} HTTP/${req.httpVersion}\r\n`
	for (let i = 0; i < req.rawHeaders.length; i += 2) {
		header += `${req.rawHeaders[i]}: ${req.rawHeaders[i + 1]}\r\n`
	}
	header += '\r\n'
	res.contentType('text').send(Buffer.concat([Buffer.from(header), req.body ?? Buffer.alloc(0)]))
})

app.listen(3000).addListener('listening', () => {
	console.log('Listening on http://localhost:3000')
})