HTTP PUT servers on Node.js and Go with calculating MD5 sums of uploaded files

server.go

//
// Usage:
//     env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o server server.go && ./server
// Test:
//     dd if=/dev/urandom of=./archive.2gb.zip bs=1024KB count=2000
//     time curl --upload-file archive.2gb.zip http://localhost:9001
//

package main

import (
	"crypto/md5"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
)

const port = 9001
const destination = "/tmp"

func sendError(w http.ResponseWriter, message string, code int) {
	w.WriteHeader(code)
	fmt.Fprint(w, message)
}

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		fmt.Printf("%s %s\n", r.Method, r.URL.Path)

		if r.Method != http.MethodPut {
			w.WriteHeader(http.StatusMethodNotAllowed)
			return
		}

		file := filepath.Join(destination, r.URL.Path)

		// file writer
		fw, err := os.OpenFile(file, os.O_WRONLY|os.O_CREATE, 0660)
		defer fw.Close()
		if err != nil {
			sendError(w, err.Error(), http.StatusInternalServerError)
			return
		}

		// md5 writer
		hw := md5.New()

		// multiwriter to write to both file and md5 hash writers
		mw := io.MultiWriter(fw, hw)

		// write body to multiwriter
		_, err = io.Copy(mw, r.Body)
		if err != nil {
			sendError(w, err.Error(), http.StatusInternalServerError)
			return
		}

		w.WriteHeader(http.StatusOK)
		fmt.Fprintf(w, "OK: %x\n", hw.Sum(nil))
	})

	fmt.Printf("Listening on port %d...\n", port)
	http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
}

server.js

//
// Usage:
//     node ./server.js
// Test:
//     dd if=/dev/urandom of=./archive.2gb.zip bs=1024KB count=2000
//     time curl --upload-file archive.2gb.zip http://localhost:9001
//

'use strict';

const fs = require('fs');
const path = require('path');
const http = require('http');
const crypto = require('crypto');

const port = 9001;
const destination = '/tmp';

function sendError(res, message = 'Internal error', status = 500) {
    console.log(`ERROR: ${message} [${code}]`);
    res.statusCode = status;
    res.end(message);
}

http.createServer()
    .on('request', (req, res) => {
        console.log(req.method, req.url);
        if (req.method !== 'PUT') {
            return sendError(res, 'Method not allowed', 405);
        }
        const file = path.join(destination, req.url);
        const writable = fs.createWriteStream(file);
        const md5 = crypto.createHash('md5');
        req.on('data', chunk => md5.update(chunk))
            .once('error', err => sendError(res, err))
            .pipe(writable)
            .once('error', err => sendError(res, err))
            .on('finish', () => res.end(`OK: ${md5.digest('hex')}\n`));
    })
    .listen(port, () => console.log(`Listening on ${port}...`));