Ajax Upload File to GoLang Server with Content Type Multipart

I'm trying to upload an audio file to a Golang server using a multipart form. However, Go returns the error:

multipart: NextPart: bufio: buffer full

I believe this indicates there is something not in the multipart format with my Javascript request. This is my Javascript:

function UploadFile(file) {
	var xhr = new XMLHttpRequest();


	if (file.type == "audio/mpeg" && file.size <= $id("MAX_FILE_SIZE").value) {
		// start upload
		var boundary = '---------------------------' + Math.floor(Math.random()*32768) + Math.floor(Math.random()*32768) + Math.floor(Math.random()*32768);

		xhr.open("POST", $id("upload").action, true);
		xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=" + boundary);
		xhr.setRequestHeader("X_FILENAME", file.name);
		xhr.send(file);
	}
}

And this is my Golang server handler:

func FileHandler(w http.ResponseWriter, r *http.Request) {
	var (
		status int
		err    error
	)
	defer func() {
		if nil != err {
			http.Error(w, err.Error(), status)
		}
	}()
	// parse request with maximum memory of _24Kilobits
	const _24K = (1 << 20) * 24
	if err = r.ParseMultipartForm(_24K); nil != err {
		fmt.Println(err)
		status = http.StatusInternalServerError
		return
	}
	for _, fheaders := range r.MultipartForm.File {
		for _, hdr := range fheaders {
			// open uploaded
			var infile multipart.File
			if infile, err = hdr.Open(); nil != err {
				status = http.StatusInternalServerError
				return
			}
			// open destination
			var outfile *os.File
			if outfile, err = os.Create("./uploaded/" + hdr.Filename); nil != err {
				status = http.StatusInternalServerError
				return
			}
			// 32K buffer copy
			var written int64
			if written, err = io.Copy(outfile, infile); nil != err {
				status = http.StatusInternalServerError
				return
			}
		w.Write([]byte("uploaded file:" + hdr.Filename + ";length:" + strconv.Itoa(int(written))))
		}
	}
}

If anyone has any ideas why I'm getting this error, I'd greatly appreciate it.

After a long, arduous battle with the Ajax request, I got it to send the right information. Here's the code I used:

var xhr = new XMLHttpRequest(),
    boundary=Math.random().toString().substr(2);

var formdata = new FormData();
formdata.append("file", file);

xhr.open("POST", $id("upload").action, true);
//xhr.setRequestHeader("content-type", "multipart/form-data; charset=utf-8; boundary=" + boundary);
xhr.send(formdata);

Note the header is no longer in use and I found you can attach data to formdata much easier than any other method such as this: https://stackoverflow.com/questions/5933949/how-to-send-multipart-form-data-form-content-by-ajax-no-jquery#5935286

Not sure whether this answer suits you, but I was able to upload the file via ajax using form-data on a client side and the following small snippet of Go code on the server:

file, handler, err := r.FormFile("img") // img is the key of the form-data
if err != nil {
	fmt.Println(err)
	return
}
defer file.Close()

fmt.Println("File is good")
fmt.Println(handler.Filename)
fmt.Println()
fmt.Println(handler.Header)


f, err := os.OpenFile(handler.Filename, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
	fmt.Println(err)
	return
}
defer f.Close()
io.Copy(f, file)

Here r is *http.Request. P.S. this just stores the file in the same folder and does not perform any security checks.