Graceful failure when websocket is request and the async mode does no…

…t support it

engineio/server.py

@@ -305,8 +305,7 @@ def _handle_connect(self, environ, start_response, transport, b64=False):
             return self._unauthorized()
 
         if transport == 'websocket':
-            s.handle_get_request(environ, start_response)
-            return self._ok()
+            return s.handle_get_request(environ, start_response)
         else:
             s.connected = True
             headers = None

engineio/socket.py

@@ -104,6 +104,10 @@ def _upgrade_websocket(self, environ, start_response):
         """Upgrade the connection from polling to websocket."""
         if self.upgraded:
             raise IOError('Socket has been upgraded already')
+        if self.server.async['websocket'] is None or \
+                self.server.async['websocket_class'] is None:
+            # the selected async mode does not support websocket
+            return self.server._bad_request()
         websocket_class = getattr(self.server.async['websocket'],
                                   self.server.async['websocket_class'])
         ws = websocket_class(self._websocket_handler)

tests/test_socket.py

@@ -204,6 +204,17 @@ def test_upgrade_no_upgrade_packet(self):
         self.assertEqual(s.queue.get().packet_type, packet.NOOP)
         self.assertFalse(s.upgraded)
 
+    def test_upgrade_not_supported(self):
+        mock_server = self._get_mock_server()
+        mock_server.async['websocket'] = None
+        mock_server.async['websocket_class'] = None
+        s = socket.Socket(mock_server, 'sid')
+        s.connected = True
+        environ = "foo"
+        start_response = "bar"
+        s._upgrade_websocket(environ, start_response)
+        mock_server._bad_request.assert_called_once_with()
+
     def test_websocket_read_write(self):
         mock_server = self._get_mock_server()
         s = socket.Socket(mock_server, 'sid')