Simple GO static web contents server.

gohttp.go

package main

import (
	"errors"
	"flag"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
)

type logging struct {
	baseHandler http.Handler
}

func (l *logging) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Printf("%s -> %s %s %s ", r.RemoteAddr, r.Method, r.Proto, r.URL)
	l.baseHandler.ServeHTTP(w, r)
}

func externalIP() (string, error) {
	ifaces, err := net.Interfaces()
	if err != nil {
		return "", err
	}

	for _, iface := range ifaces {
		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
			continue // interface down or loopback interface
		}

		addrs, err := iface.Addrs()
		if err != nil {
			return "", err
		}

		for _, addr := range addrs {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}
			if ip == nil || ip.IsLoopback() {
				continue
			}
			ip = ip.To4()
			if ip == nil {
				continue // not an ipv4 address
			}
			return ip.String(), nil
		}
	}
	return "", errors.New("are you connected to the network?")
}

var port int
var host string
var homeDir string

func init() {
	addr, _ := externalIP()
	flag.IntVar(&port, "port", 8000, "listening port")
	flag.StringVar(&host, "addr", addr, "bind address")
	flag.Parse()

	homeDir = flag.Arg(0)
	if homeDir == "" {
		homeDir = "./"
	}
}

func main() {
	if fi, err := os.Stat(homeDir); err != nil {
		panic(err)
	} else if !fi.IsDir() {
		fmt.Printf("%s is not directory.\n", homeDir)
		os.Exit(1)
	}

	log.Printf("serve on %s:%d at %s\n", host, port, homeDir)
	handler := &logging{baseHandler: http.FileServer(http.Dir(homeDir))}
	panic(http.ListenAndServe(fmt.Sprintf("%s:%d", host, port), handler))
}