src/uploader/main.go

   1 /*
   2 uploader -- simplest form file uploader
   3 Copyright (C) 2018-2019 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "bufio"
  22         "encoding/base64"
  23         "encoding/hex"
  24         "flag"
  25         "fmt"
  26         "html/template"
  27         "io"
  28         "io/ioutil"
  29         "log"
  30         "mime"
  31         "net"
  32         "net/http"
  33         "os"
  34         "os/exec"
  35         "strings"
  36         "time"
  37
  38         "golang.org/x/crypto/blake2b"
  39         "golang.org/x/net/netutil"
  40 )
  41
  42 const (
  43         WriteBufSize     = 1 << 20
  44         FileFieldName    = "fileupload"
  45         CommentFieldName = "comment"
  46
  47         SendmailCmd = "/usr/sbin/sendmail"
  48 )
  49
  50 var (
  51         Index = template.Must(template.New("index").Parse(`<html>
  52 <head><title>Upload</title></head><body>
  53 <form enctype="multipart/form-data" action="/upload/" method="post">
  54 <input type="file" name="{{.}}" /><br/>
  55 <label for="comment">Optional comment:</label>
  56 <textarea name="comment" cols="80" rows="25" name="comment"></textarea><br/>
  57 <input type="submit" />
  58 </form></body></html>`))
  59         NotifyFromAddr *string
  60         NotifyToAddr   *string
  61 )
  62
  63 func notify(filename, timestamp string, size int64, comment string) {
  64         if *NotifyToAddr == "" {
  65                 return
  66         }
  67         cmd := exec.Command(SendmailCmd, *NotifyToAddr)
  68         cmd.Stdin = io.MultiReader(
  69                 strings.NewReader(fmt.Sprintf(
  70                         `From: %s
  71 To: %s
  72 Subject: %s
  73 MIME-Version: 1.0
  74 Content-Type: text/plain; charset=utf-8
  75 Content-Transfer-Encoding: base64
  76
  77 `,
  78                         *NotifyFromAddr,
  79                         *NotifyToAddr,
  80                         mime.BEncoding.Encode("UTF-8", fmt.Sprintf(
  81                                 "%s (%d KiB)", filename, size/1024,
  82                         )),
  83                 )),
  84                 strings.NewReader(base64.StdEncoding.EncodeToString([]byte(fmt.Sprintf(
  85                         "Timestamp: %s\nSize: %d bytes\nComment: %s\n",
  86                         timestamp,
  87                         size,
  88                         comment,
  89                 )))),
  90         )
  91         cmd.Run()
  92 }
  93
  94 func upload(w http.ResponseWriter, r *http.Request) {
  95         log.Println(r.RemoteAddr, "connected")
  96         if r.Method == http.MethodGet {
  97                 if err := Index.Execute(w, FileFieldName); err != nil {
  98                         log.Println(r.RemoteAddr, err)
  99                 }
 100                 return
 101         }
 102         mr, err := r.MultipartReader()
 103         if err != nil {
 104                 log.Println(r.RemoteAddr, err)
 105                 return
 106         }
 107         p, err := mr.NextPart()
 108         if err != nil {
 109                 log.Println(r.RemoteAddr, err)
 110                 return
 111         }
 112         if p.FormName() != FileFieldName {
 113                 log.Println(r.RemoteAddr, "non file form field")
 114                 return
 115         }
 116         h, err := blake2b.New512(nil)
 117         if err != nil {
 118                 panic(err)
 119         }
 120         fn := time.Now().Format(time.RFC3339Nano)
 121         fnOrig := p.FileName()
 122         fd, err := os.OpenFile(fn+".part", os.O_WRONLY|os.O_CREATE, 0600)
 123         if err != nil {
 124                 log.Println(r.RemoteAddr, fn, fnOrig, err)
 125                 return
 126         }
 127         fdBuf := bufio.NewWriterSize(fd, WriteBufSize)
 128         mw := io.MultiWriter(fdBuf, h)
 129         n, err := io.Copy(mw, p)
 130         if err != nil {
 131                 log.Println(r.RemoteAddr, fn, fnOrig, err)
 132                 fd.Close()
 133                 return
 134         }
 135         if n == 0 {
 136                 log.Println(r.RemoteAddr, fn, fnOrig, "empty")
 137                 os.Remove(fn + ".part")
 138                 fd.Close()
 139                 fmt.Fprintf(w, "Empty file")
 140                 return
 141         }
 142         if err = fdBuf.Flush(); err != nil {
 143                 log.Println(r.RemoteAddr, fn, fnOrig, err)
 144                 fd.Close()
 145                 return
 146         }
 147         fd.Close()
 148         sum := hex.EncodeToString(h.Sum(nil))
 149         if err = os.Rename(fn+".part", fn); err != nil {
 150                 log.Println(r.RemoteAddr, fn, fnOrig, n, sum, err)
 151                 return
 152         }
 153         fmt.Fprintf(w, "Timestamp: %s\nBytes: %d\nBLAKE2b: %s\n", fn, n, sum)
 154         log.Println(r.RemoteAddr, fn, fnOrig, n, sum)
 155         p, err = mr.NextPart()
 156         if err != nil || p.FormName() != CommentFieldName {
 157                 go notify(fnOrig, fn, n, "")
 158                 return
 159         }
 160         comment, err := ioutil.ReadAll(p)
 161         if err != nil || len(comment) == 0 {
 162                 go notify(fnOrig, fn, n, "")
 163                 return
 164         }
 165         ioutil.WriteFile(fn+".txt", comment, os.FileMode(0600))
 166         go notify(fnOrig, fn, n, string(comment))
 167 }
 168
 169 func main() {
 170         bind := flag.String("bind", "[::]:8086", "Address to bind to")
 171         conns := flag.Int("conns", 2, "Maximal number of connections")
 172         NotifyFromAddr = flag.String("notify-from", "uploader@example.com", "Address notifications are send to")
 173         NotifyToAddr = flag.String("notify-to", "", "Address notifications are send from")
 174         flag.Parse()
 175         if len(*NotifyFromAddr) == 0 && len(*NotifyToAddr) > 0 {
 176                 log.Fatalln("notify-from address can not be empty, if notify-to is set")
 177         }
 178         ln, err := net.Listen("tcp", *bind)
 179         if err != nil {
 180                 log.Fatalln(err)
 181         }
 182         log.Println("listening", *bind)
 183         ln = netutil.LimitListener(ln, *conns)
 184         s := &http.Server{
 185                 ReadHeaderTimeout: 10 * time.Second,
 186                 MaxHeaderBytes:    10 * (1 << 10),
 187         }
 188         http.HandleFunc("/upload/", upload)
 189         s.Serve(ln)
 190 }