src/uploader/main.go

   1 /*
   2 uploader -- simplest form file uploader
   3 Copyright (C) 2018-2019 Sergey Matveev <stargrave@stargrave.org>
   4 */
   5
   6 package main
   7
   8 import (
   9         "bufio"
  10         "encoding/hex"
  11         "flag"
  12         "fmt"
  13         "html/template"
  14         "io"
  15         "log"
  16         "net"
  17         "net/http"
  18         "os"
  19         "time"
  20
  21         "golang.org/x/crypto/blake2b"
  22         "golang.org/x/net/netutil"
  23 )
  24
  25 const (
  26         WriteBufSize     = 1 << 20
  27         FileFieldName    = "fileupload"
  28         CommentFieldName = "comment"
  29 )
  30
  31 var (
  32         Index = template.Must(template.New("index").Parse(`<html>
  33 <head><title>Upload</title></head><body>
  34 <form enctype="multipart/form-data" action="/upload/" method="post">
  35 <input type="file" name="{{.}}" /><br/>
  36 <label for="comment">Optional comment:</label>
  37 <textarea name="comment" cols="80" rows="25" name="comment"></textarea><br/>
  38 <input type="submit" />
  39 </form></body></html>`))
  40 )
  41
  42 func upload(w http.ResponseWriter, r *http.Request) {
  43         log.Println(r.RemoteAddr, "connected")
  44         if r.Method == http.MethodGet {
  45                 if err := Index.Execute(w, FileFieldName); err != nil {
  46                         log.Println(r.RemoteAddr, err)
  47                 }
  48                 return
  49         }
  50         mr, err := r.MultipartReader()
  51         if err != nil {
  52                 log.Println(r.RemoteAddr, err)
  53                 return
  54         }
  55         p, err := mr.NextPart()
  56         if err != nil {
  57                 log.Println(r.RemoteAddr, err)
  58                 return
  59         }
  60         if p.FormName() != FileFieldName {
  61                 log.Println(r.RemoteAddr, "non file form field")
  62                 return
  63         }
  64         h, err := blake2b.New256(nil)
  65         if err != nil {
  66                 panic(err)
  67         }
  68         fn := time.Now().Format(time.RFC3339Nano)
  69         fd, err := os.OpenFile(fn+".part", os.O_WRONLY|os.O_CREATE, 0600)
  70         if err != nil {
  71                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  72                 return
  73         }
  74         fdBuf := bufio.NewWriterSize(fd, WriteBufSize)
  75         mw := io.MultiWriter(fdBuf, h)
  76         n, err := io.Copy(mw, p)
  77         if err != nil {
  78                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  79                 fd.Close()
  80                 return
  81         }
  82         if n == 0 {
  83                 log.Println(r.RemoteAddr, fn, p.FileName(), "empty")
  84                 os.Remove(fn + ".part")
  85                 fd.Close()
  86                 fmt.Fprintf(w, "Empty file")
  87                 return
  88         }
  89         if err = fdBuf.Flush(); err != nil {
  90                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  91                 fd.Close()
  92                 return
  93         }
  94         fd.Close()
  95         sum := hex.EncodeToString(h.Sum(nil))
  96         if err = os.Rename(fn+".part", fn); err != nil {
  97                 log.Println(r.RemoteAddr, fn, p.FileName(), n, sum, err)
  98                 return
  99         }
 100         fmt.Fprintf(w, "Timestamp: %s\nBytes: %d\nBLAKE2b: %s\n", fn, n, sum)
 101         log.Println(r.RemoteAddr, fn, p.FileName(), n, sum)
 102         p, err = mr.NextPart()
 103         if err != nil || p.FormName() != CommentFieldName {
 104                 return
 105         }
 106         comment, err := ioutil.ReadAll(p)
 107         if err != nil || len(comment) == 0 {
 108                 return
 109         }
 110         ioutil.WriteFile(fn+".txt", comment, os.FileMode(0600))
 111         go notify(fn, n, string(comment))
 112 }
 113
 114 func main() {
 115         bind := flag.String("bind", "[::]:8086", "Address to bind to")
 116         conns := flag.Int("conns", 2, "Maximal number of connections")
 117         flag.Parse()
 118         ln, err := net.Listen("tcp", *bind)
 119         if err != nil {
 120                 panic(err)
 121         }
 122         log.Println("listening", *bind)
 123         ln = netutil.LimitListener(ln, *conns)
 124         s := &http.Server{
 125                 ReadHeaderTimeout: 10 * time.Second,
 126                 MaxHeaderBytes:    10 * (1 << 10),
 127         }
 128         http.HandleFunc("/upload/", upload)
 129         s.Serve(ln)
 130 }