main.go

   1 /*
   2 uploader -- simplest form file uploader
   3 Copyright (C) 2018-2023 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         "bytes"
  23         "encoding/base64"
  24         "encoding/hex"
  25         "flag"
  26         "fmt"
  27         "html/template"
  28         "io"
  29         "log"
  30         "mime"
  31         "net"
  32         "net/http"
  33         "os"
  34         "os/exec"
  35         "strconv"
  36         "strings"
  37         "sync"
  38         "time"
  39
  40         "go.cypherpunks.ru/recfile"
  41         "go.cypherpunks.ru/tai64n/v2"
  42         "golang.org/x/net/netutil"
  43         "lukechampine.com/blake3"
  44 )
  45
  46 const (
  47         WriteBufSize     = 1 << 20
  48         FileFieldName    = "file"
  49         CommentFieldName = "comment"
  50
  51         SendmailCmd = "/usr/sbin/sendmail"
  52 )
  53
  54 var (
  55         Index = template.Must(template.New("index").Parse(`<html>
  56 <head><title>Upload</title></head><body>
  57 Example command line usage:
  58 <pre>
  59 $ curl -F file=@somedata.tar.gpg [-F comment="optional comment"] http://.../upload/
  60 $ b3sum somedata.tar.gpg # to verify BLAKE3-256 checksum
  61 </pre>
  62 <form enctype="multipart/form-data" action="/upload/" method="post">
  63 <label for="file">File to upload:</label><br/>
  64 <input name="file" type="file" name="{{.}}" /><br/>
  65 <label for="comment">Optional comment:</label></br>
  66 <textarea name="comment" cols="80" rows="25" name="comment"></textarea><br/>
  67 <input type="submit" />
  68 </form></body></html>`))
  69         NotifyFromAddr *string
  70         NotifyToAddr   *string
  71         Jobs           sync.WaitGroup
  72 )
  73
  74 func upload(w http.ResponseWriter, r *http.Request) {
  75         log.Println(r.RemoteAddr, "connected")
  76         if r.Method == http.MethodGet {
  77                 if err := Index.Execute(w, FileFieldName); err != nil {
  78                         log.Println(r.RemoteAddr, err)
  79                 }
  80                 return
  81         }
  82         mr, err := r.MultipartReader()
  83         if err != nil {
  84                 log.Println(r.RemoteAddr, err)
  85                 return
  86         }
  87         p, err := mr.NextPart()
  88         if err != nil {
  89                 log.Println(r.RemoteAddr, err)
  90                 return
  91         }
  92         if p.FormName() != FileFieldName {
  93                 log.Println(r.RemoteAddr, "non file form field")
  94                 return
  95         }
  96         t := time.Now()
  97         ts := new(tai64n.TAI64N)
  98         ts.FromTime(t)
  99         tai := tai64n.Encode(ts[:])[1:]
 100         fnOrig := p.FileName()
 101         fd, err := os.OpenFile(tai+".part", os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
 102         if err != nil {
 103                 log.Println(r.RemoteAddr, tai, fnOrig, err)
 104                 return
 105         }
 106         fdBuf := bufio.NewWriterSize(fd, WriteBufSize)
 107         h := blake3.New(32, nil)
 108         mw := io.MultiWriter(fdBuf, h)
 109         n, err := io.Copy(mw, p)
 110         if err != nil {
 111                 log.Println(r.RemoteAddr, tai, fnOrig, err)
 112                 fd.Close()
 113                 return
 114         }
 115         if n == 0 {
 116                 log.Println(r.RemoteAddr, tai, fnOrig, "empty")
 117                 os.Remove(tai + ".part")
 118                 fd.Close()
 119                 fmt.Fprintf(w, "Empty file")
 120                 return
 121         }
 122         if err = fdBuf.Flush(); err != nil {
 123                 log.Println(r.RemoteAddr, tai, fnOrig, err)
 124                 fd.Close()
 125                 return
 126         }
 127         if err = fd.Sync(); err != nil {
 128                 log.Println(r.RemoteAddr, tai, fnOrig, err)
 129                 fd.Close()
 130                 return
 131         }
 132         fd.Close()
 133         sum := hex.EncodeToString(h.Sum(nil))
 134         if err = os.Rename(tai+".part", tai); err != nil {
 135                 log.Println(r.RemoteAddr, tai, fnOrig, n, sum, err)
 136                 return
 137         }
 138
 139         var rec bytes.Buffer
 140         wr := recfile.NewWriter(&rec)
 141         if _, err = wr.WriteFields(
 142                 recfile.Field{Name: "TAI64N", Value: tai},
 143                 recfile.Field{Name: "Size", Value: strconv.FormatInt(n, 10)},
 144                 recfile.Field{Name: "Checksum", Value: sum},
 145         ); err != nil {
 146                 log.Println(r.RemoteAddr, tai, fnOrig, n, sum, err)
 147                 return
 148         }
 149         if _, err = w.Write(rec.Bytes()); err == nil {
 150                 log.Println(r.RemoteAddr, tai, fnOrig, n, sum)
 151         } else {
 152                 log.Println(r.RemoteAddr, tai, fnOrig, n, sum, err)
 153                 return
 154         }
 155
 156         if _, err = wr.WriteFields(
 157                 recfile.Field{Name: "Filename", Value: fnOrig},
 158         ); err != nil {
 159                 log.Println(r.RemoteAddr, tai, fnOrig, n, sum, err)
 160                 return
 161         }
 162
 163         var commentLines []string
 164         p, err = mr.NextPart()
 165         if err == nil && p.FormName() == CommentFieldName {
 166                 comment, err := io.ReadAll(p)
 167                 if err == nil && len(comment) > 0 {
 168                         commentLines = strings.Split(string(comment), "\n")
 169                         wr.WriteFieldMultiline("Comment", commentLines)
 170                 }
 171         }
 172
 173         os.WriteFile(tai+".rec", rec.Bytes(), os.FileMode(0666))
 174         if *NotifyToAddr == "" {
 175                 return
 176         }
 177         cmd := exec.Command(SendmailCmd, *NotifyToAddr)
 178         cmd.Stdin = io.MultiReader(
 179                 strings.NewReader(fmt.Sprintf(
 180                         `From: %s
 181 To: %s
 182 Subject: %s
 183 MIME-Version: 1.0
 184 Content-Type: text/plain; charset=utf-8
 185 Content-Transfer-Encoding: base64
 186
 187 `,
 188                         *NotifyFromAddr,
 189                         *NotifyToAddr,
 190                         mime.BEncoding.Encode("UTF-8", fmt.Sprintf("%s (%d KiB)", fnOrig, n/1024)),
 191                 )),
 192                 strings.NewReader(base64.StdEncoding.EncodeToString(rec.Bytes())),
 193         )
 194         Jobs.Add(1)
 195         go func() {
 196                 cmd.Run()
 197                 Jobs.Done()
 198         }()
 199 }
 200
 201 func main() {
 202         doUCSPI := flag.Bool("ucspi", false, "Work as UCSPI-TCP service")
 203         bind := flag.String("bind", "[::]:8086", "Address to bind to")
 204         conns := flag.Int("conns", 2, "Maximal number of connections")
 205         NotifyFromAddr = flag.String("notify-from", "uploader@example.com", "Address notifications are sent to")
 206         NotifyToAddr = flag.String("notify-to", "", "Address notifications are sent from")
 207         flag.Parse()
 208         log.SetFlags(log.Lshortfile)
 209         if !*doUCSPI {
 210                 log.SetOutput(os.Stdout)
 211         }
 212         if len(*NotifyFromAddr) == 0 && len(*NotifyToAddr) > 0 {
 213                 log.Fatalln("notify-from address can not be empty, if notify-to is set")
 214         }
 215         s := &http.Server{
 216                 ReadHeaderTimeout: 10 * time.Second,
 217                 MaxHeaderBytes:    10 * (1 << 10),
 218         }
 219         http.HandleFunc("/upload/", upload)
 220         if *doUCSPI {
 221                 s.SetKeepAlivesEnabled(false)
 222                 ln := &UCSPI{}
 223                 s.ConnState = connStater
 224                 err := s.Serve(ln)
 225                 if _, ok := err.(UCSPIAlreadyAccepted); !ok {
 226                         log.Fatalln(err)
 227                 }
 228                 Jobs.Wait()
 229         } else {
 230                 ln, err := net.Listen("tcp", *bind)
 231                 if err != nil {
 232                         log.Fatalln(err)
 233                 }
 234                 log.Println("listening", *bind)
 235                 ln = netutil.LimitListener(ln, *conns)
 236                 if err = s.Serve(ln); err != nil {
 237                         log.Fatalln(err)
 238                 }
 239         }
 240 }