dir-server

main.go (5334B)

---

 /*dir-server - simple http or https server for current directory
 
   Copyright (C) 2019-2020 Brian C. Lane <bcl@brianlane.com>
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 package main
 
 import (
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
 	"flag"
 	"fmt"
 	"log"
 	"math/big"
 	"net/http"
 	"os"
 	"time"
 )
 
 type cmdlineArgs struct {
 	ListenIP   string
 	ListenPort int
 	TLS        bool
 	Cert       string
 	Key        string
 	SinglePage bool
 	Path       string
 }
 
 var cfg = cmdlineArgs{
 	ListenIP:   "0.0.0.0",
 	ListenPort: 8000,
 	TLS:        false,
 	Cert:       "/var/tmp/cert.pem",
 	Key:        "/var/tmp/key.pem",
 	SinglePage: false,
 	Path:       "./",
 }
 
 func init() {
 	flag.StringVar(&cfg.ListenIP, "ip", cfg.ListenIP, "IP Address to Listen to")
 	flag.IntVar(&cfg.ListenPort, "port", cfg.ListenPort, "Port to listen to")
 	flag.BoolVar(&cfg.TLS, "tls", cfg.TLS, "Use https instead of http")
 	flag.StringVar(&cfg.Cert, "cert", cfg.Cert, "Path to temporary cert.pem")
 	flag.StringVar(&cfg.Key, "key", cfg.Key, "Path to temporary key.pem")
 	flag.BoolVar(&cfg.SinglePage, "single", cfg.SinglePage, "Single page app, direct all unknown routes to index.html")
 	flag.StringVar(&cfg.Path, "path", cfg.Path, "Path to serve files from")
 
 	flag.Parse()
 }
 
 func publicKey(priv interface{}) interface{} {
 	switch k := priv.(type) {
 	case *ecdsa.PrivateKey:
 		return &k.PublicKey
 	default:
 		return nil
 	}
 }
 
 // This generates a self-signed cert good for 6 hours using ecdsa P256 curve
 func makeSelfSigned(cert, key string) {
 	hostname, err := os.Hostname()
 	if err != nil {
 		log.Fatalf("Error getting hostname: %s", err)
 	}
 
 	// these are temporary certs, only valid for 6 hours
 	notBefore := time.Now()
 	notAfter := notBefore.Add(6 * time.Hour)
 
 	var priv interface{}
 	priv, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
 	if err != nil {
 		log.Fatalf("Failed to generate private key: %s", err)
 	}
 	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
 	if err != nil {
 		log.Fatalf("Failed to generate serial number: %s", err)
 	}
 	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
 
 	template := x509.Certificate{
 		SerialNumber: serialNumber,
 		Subject: pkix.Name{
 			Organization: []string{"Random Bits UNL"},
 		},
 		NotBefore:             notBefore,
 		NotAfter:              notAfter,
 		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
 		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
 		BasicConstraintsValid: true,
 		DNSNames:              []string{hostname},
 	}
 	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
 	if err != nil {
 		log.Fatalf("Failed to create certificate: %s", err)
 	}
 
 	certOut, err := os.Create(cert)
 	if err != nil {
 		log.Fatalf("Failed to open %s for writing: %s", cert, err)
 	}
 	if err := pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
 		log.Fatalf("Failed to write data to cert.pem: %s", err)
 	}
 	if err := certOut.Close(); err != nil {
 		log.Fatalf("Error closing %s: %s", cert, err)
 	}
 	log.Printf("wrote %s\n", cert)
 
 	keyOut, err := os.OpenFile(key, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
 		log.Fatalf("Failed to open %s for writing: %s", key, err)
 	}
 	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
 	if err != nil {
 		log.Fatalf("Unable to marshal private key: %v", err)
 	}
 	if err := pem.Encode(keyOut, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes}); err != nil {
 		log.Fatalf("Failed to write data to %s: %s", key, err)
 	}
 	if err := keyOut.Close(); err != nil {
 		log.Fatalf("Error closing %s: %s", key, err)
 	}
 	log.Printf("wrote %s\n", key)
 }
 
 type singlePageFile struct {
 	http.File
 }
 
 // singlePageFileServer is an http.FileSystem that returns index.html for all non-existant paths
 type singlePageFileServer struct {
 	http.FileSystem
 }
 
 func (fs singlePageFileServer) Open(name string) (http.File, error) {
 	file, err := fs.FileSystem.Open(name)
 	if err != nil {
 		file, err = fs.FileSystem.Open("/index.html")
 		if err != nil {
 			return nil, err
 		}
 	}
 	return singlePageFile{file}, nil
 }
 
 func main() {
 	if !cfg.SinglePage {
 		http.Handle("/", http.FileServer(http.Dir(cfg.Path)))
 	} else {
 		fs := singlePageFileServer{http.Dir(cfg.Path)}
 		http.Handle("/", http.FileServer(fs))
 	}
 	listen := fmt.Sprintf("%s:%d", cfg.ListenIP, cfg.ListenPort)
 
 	if !cfg.TLS {
 		if err := http.ListenAndServe(listen, nil); err != nil {
 			panic(err)
 		}
 	} else {
 		makeSelfSigned(cfg.Cert, cfg.Key)
 		if err := http.ListenAndServeTLS(listen, cfg.Cert, cfg.Key, nil); err != nil {
 			panic(err)
 		}
 
 	}
 }