httpserver for quickly sharing a folder on disks contents

main.go

/*
  syntax:
	httpserver port path cidr

  arguments are optional but expected in the above order

  current directory via just . works
*/

package main

import (
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"strconv"
	"strings"
)

var (
	Port int
	Path string
	Acl  *net.IPNet
)

// log/acl wrapper
func httpLogger(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		remoteIP := net.ParseIP(strings.Split(r.RemoteAddr, ":")[0])
		if Acl.Contains(remoteIP) {
			log.Println(r.RemoteAddr, r.URL)
			h.ServeHTTP(w, r)
			return
		}

		log.Println("denied:", r.RemoteAddr)
		http.Error(w, "Permission Denied", http.StatusForbidden)
	})
}

func init() {
	// configure console logging
	log.SetOutput(os.Stdout)

	// assume some defaults
	Port = 8888
	Path = "."
	_, Acl, _ = net.ParseCIDR("0.0.0.0/0")

	// read/set args if any
	if len(os.Args) >= 2 {
		Port, _ = strconv.Atoi(os.Args[1])
	}
	if len(os.Args) >= 3 {
		Path = os.Args[2]
	}
	if len(os.Args) >= 4 {
		_, Acl, _ = net.ParseCIDR(os.Args[3])
	}

}

func main() {
	log.Println("sharing on port", Port)

	// define server
	srv := &http.Server{
		Addr: fmt.Sprintf(":%d", Port),
		Handler: httpLogger(http.FileServer(http.Dir(Path))),
		ErrorLog: log.New(os.Stdout, "httpserver: ", log.LstdFlags),
	}

	// start server
	if err := srv.ListenAndServe(); err != nil {
		panic(err)
	}
}