mulitpart range req response

gistfile1.txt

var mpbody bytes.Buffer
	mpw := multipart.NewWriter(&mpbody)
	defer mpw.Close()
	mpw.SetBoundary(m.boundary)

	for _, rng := range ranges {
		start, end := rng[0], rng[1]
		mimeh := make(textproto.MIMEHeader)
		mimeh.Set("Content-Type", m.contentType)
		mimeh.Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", start, end, len(m.body)))

		seg := m.body[start : end+1]

		pw, err := mpw.CreatePart(mimeh)
		if err != nil {
			return err
		}

		if _, err := pw.Write(seg); err != nil {
			return err
		}
	}

	res.ContentLength = int64(len(mpbody.Bytes()))
	res.Body = ioutil.NopCloser(bytes.NewReader(mpbody.Bytes()))
	res.Header.Set("Content-Type", fmt.Sprintf("multipart/byteranges; boundary=%s", m.boundary))

	return nil