CODEWITHSUNDEEP
htmlhttpgofile-upload
aviv
aviv

Reputation: 2809

ParseMultipartForm always fails although the form is valid

I am trying to handle uploaded files in go http server. But calling ParseMultipartForm always fails with strange error: "multipart: NextPart: EOF" although the form is valid. Debugging it, I can see that I get the full encoded data, and size and parameters. Yet it fails parsing.

Here is the html form:

<html>
<head>
     <title>Upload file</title>
</head>
<body>
<form enctype="multipart/form-data" action="http://localhost:8080/uploadLogo/" method="post">
    <input type="file" name="uploadfile" />
    <input type="hidden" name="token" value="{{.}}" />
    <input type="submit" value="upload" />
</form>
</body>
</html>

And here is the relevant upload function:

// upload logic
func upload(w http.ResponseWriter, r *http.Request) {
    fmt.Println("method:", r.Method)
    if r.Method == "GET" {
        // crutime := time.Now().Unix()
        // h := md5.New()
        // io.WriteString(h, strconv.FormatInt(crutime, 10))
        // token := fmt.Sprintf("%x", h.Sum(nil))

        // t, _ := template.ParseFiles("upload.gtpl")
        // t.Execute(w, token)
    } else {
        err := r.ParseMultipartForm(5 * 1024 * 1024 * 1024)
        if err != nil {
            fmt.Println("Error ParseMultipartForm: ", err) // here it fails !!! with: "multipart: NextPart: EOF"
            return
        }

        file, handler, err := r.FormFile("uploadfile")
        if err != nil {
            fmt.Println("Error parsing file", err)
            return
        }
        defer file.Close()
        fmt.Fprintf(w, "%v", handler.Header)
        fmt.Println("filename:", handler.Filename)
        f, err := os.OpenFile(logosDir + handler.Filename, os.O_WRONLY|os.O_CREATE, 0666)
        if err != nil {
            fmt.Println(err)
            return
        }
        defer f.Close()
        io.Copy(f, file)
   }
}

Couldn't understand why that happens.

Here is how I start my server:

func uploadLogoHandler(w http.ResponseWriter, r *http.Request) {
    //fmt.Fprintf(w, "viewLogoHandler, Path: %s!", r.URL.Path[1:])
    bodyBytes, _ := ioutil.ReadAll(r.Body)
    bodyString := string(bodyBytes)
    writeToLog("uploadLogoHandler:" + r.URL.Path, "bodyString length:" + strconv.Itoa(len(bodyString)))
    upload(w, r)
}

///////////////////////////////////////////////////////////////////////////////////////
// main

func main() {
    if(len(os.Args) < 2) {
        fmt.Println("Usage: receiver [port number]")
        os.Exit(1)
    }

    port := os.Args[1]

    s := &http.Server{
        Addr:           ":" + port,
        ReadTimeout:    10 * time.Second,
        WriteTimeout:   10 * time.Second,
    }   
    http.HandleFunc("/uploadLogo/", uploadLogoHandler)
    http.HandleFunc("/", handler)
    log.Fatal(s.ListenAndServe())
}

Upvotes: 1

Views: 4397

Answers (1)

aviv
aviv

Reputation: 2809

As writing the question I have already found the problem. It is in the handle function. I read all the stream data before calling the upload function. Here is the revised code of the handler, and now everything works:

func uploadLogoHandler(w http.ResponseWriter, r *http.Request) {
    writeToLog("uploadLogoHandler:" + r.URL.Path, "")
    upload(w, r)
}

If I understand correctly so the error: "multipart: NextPart: EOF" means that the form is empty - and it was empty because I emptied the buffer stream before.

Hope it will help others. Best.

Upvotes: 2

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