[Modify] Polish it

websocket-sharp/Ext.cs

@@ -942,31 +942,20 @@ namespace WebSocketSharp
       this Stream stream, byte[] bytes, int bufferLength, Action completed, Action<Exception> error)
     {
       var input = new MemoryStream (bytes);
-      var buff = new byte[bufferLength];
+      input.CopyToAsync (
+        stream,
+        bufferLength,
+        () => {
+          if (completed != null)
+            completed ();
 
-      AsyncCallback callback = null;
-      callback = ar => {
-        try {
-          var nread = input.EndRead (ar);
-          if (nread <= 0) {
-            if (completed != null)
-              completed ();
-
-            input.Dispose ();
-            return;
-          }
-
-          stream.Write (buff, 0, nread);
-          input.BeginRead (buff, 0, bufferLength, callback, null);
-        }
-        catch (Exception ex) {
+          input.Dispose ();
+        },
+        ex => {
           input.Dispose ();
           if (error != null)
             error (ex);
-        }
-      };
-
-      input.BeginRead (buff, 0, bufferLength, callback, null);
+        });
     }
 
     #endregion