[Modify] Replace it

websocket-sharp/WebSocket.cs

@@ -677,11 +677,8 @@ namespace WebSocketSharp
         throw new WebSocketException (CloseStatusCode.PolicyViolation, msg);
       }
 
-      if (_protocol != null
-          && !_context.SecWebSocketProtocols.Contains (protocol => protocol == _protocol)
-      ) {
-        _protocol = null;
-      }
+      if (_protocol != null)
+        processSecWebSocketProtocolHeader (_context.SecWebSocketProtocols);
 
       if (!_ignoreExtensions)
         processSecWebSocketExtensionsHeader (_context.Headers["Sec-WebSocket-Extensions"]);
@@ -1257,6 +1254,15 @@ namespace WebSocketSharp
       }
     }
 
+    // As server
+    private void processSecWebSocketProtocolHeader (IEnumerable<string> values)
+    {
+      if (values.Contains (p => p == _protocol))
+        return;
+
+      _protocol = null;
+    }
+
     private bool processUnsupportedFrame (WebSocketFrame frame)
     {
       _logger.Fatal ("An unsupported frame:" + frame.PrintToString (false));