skip md5 validation if Content-MD5 is not provided

weed/storage/needle/needle_parse_upload.go

@@ -83,11 +83,11 @@ func ParseUpload(r *http.Request, sizeLimit int64, bytesBuffer *bytes.Buffer) (p
 		}
 	}
 
-	// md5
-	h := md5.New()
-	h.Write(pu.UncompressedData)
-	pu.ContentMd5 = base64.StdEncoding.EncodeToString(h.Sum(nil))
+	// verify Content-MD5
 	if expectedChecksum := r.Header.Get("Content-MD5"); expectedChecksum != "" {
+		h := md5.New()
+		h.Write(pu.UncompressedData)
+		pu.ContentMd5 = base64.StdEncoding.EncodeToString(h.Sum(nil))
 		if expectedChecksum != pu.ContentMd5 {
 			e = fmt.Errorf("Content-MD5 did not match md5 of file data expected [%s] received [%s] size %d", expectedChecksum, pu.ContentMd5, len(pu.UncompressedData))
 			return