src/uploader/main.go

   1 /*
   2 uploader -- simplest form file uploader
   3 Copyright (C) 2018 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/blake2s"
  22         "golang.org/x/net/netutil"
  23 )
  24
  25 const (
  26         WriteBufSize  = 1 << 20
  27         FileFieldName = "fileupload"
  28 )
  29
  30 var (
  31         Index = template.Must(template.New("index").Parse(`<html>
  32 <head><title>Upload</title></head><body>
  33 <form enctype="multipart/form-data" action="/upload/" method="post">
  34 <input type="file" name="{{.}}" /><input type="submit" />
  35 </form></body></html>`))
  36 )
  37
  38 func upload(w http.ResponseWriter, r *http.Request) {
  39         log.Println(r.RemoteAddr, "connected")
  40         if r.Method == http.MethodGet {
  41                 if err := Index.Execute(w, FileFieldName); err != nil {
  42                         log.Println(r.RemoteAddr, err)
  43                 }
  44                 return
  45         }
  46         mr, err := r.MultipartReader()
  47         if err != nil {
  48                 log.Println(r.RemoteAddr, err)
  49                 return
  50         }
  51         p, err := mr.NextPart()
  52         if err != nil {
  53                 log.Println(r.RemoteAddr, err)
  54                 return
  55         }
  56         if p.FormName() != FileFieldName {
  57                 log.Println(r.RemoteAddr, "non file form field")
  58                 return
  59         }
  60         h, err := blake2s.New256(nil)
  61         if err != nil {
  62                 panic(err)
  63         }
  64         fn := time.Now().Format(time.RFC3339Nano)
  65         fd, err := os.OpenFile(fn+".part", os.O_WRONLY|os.O_CREATE, 0600)
  66         if err != nil {
  67                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  68                 return
  69         }
  70         fdBuf := bufio.NewWriterSize(fd, WriteBufSize)
  71         mw := io.MultiWriter(fdBuf, h)
  72         n, err := io.Copy(mw, p)
  73         if err != nil {
  74                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  75                 fd.Close()
  76                 return
  77         }
  78         if err = fdBuf.Flush(); err != nil {
  79                 log.Println(r.RemoteAddr, fn, p.FileName(), err)
  80                 fd.Close()
  81                 return
  82         }
  83         fd.Close()
  84         sum := hex.EncodeToString(h.Sum(nil))
  85         if err = os.Rename(fn+".part", fn); err != nil {
  86                 log.Println(r.RemoteAddr, fn, p.FileName(), n, sum, err)
  87                 return
  88         }
  89         fmt.Fprintf(w, "bytes: %d\nBLAKE2s: %s\n", n, sum)
  90         log.Println(r.RemoteAddr, fn, p.FileName(), n, sum)
  91 }
  92
  93 func main() {
  94         bind := flag.String("bind", "[::]:8086", "Address to bind to")
  95         conns := flag.Int("conns", 2, "Maximal number of connections")
  96         flag.Parse()
  97         ln, err := net.Listen("tcp", *bind)
  98         if err != nil {
  99                 panic(err)
 100         }
 101         log.Println("listening", *bind)
 102         ln = netutil.LimitListener(ln, *conns)
 103         s := &http.Server{
 104                 ReadHeaderTimeout: 10 * time.Second,
 105                 MaxHeaderBytes:    10 * (1 << 10),
 106         }
 107         http.HandleFunc("/upload/", upload)
 108         s.Serve(ln)
 109 }