patches misplaced changes fom issue/16592

* UserController: first check for param 'backUrl' before using referer

original author: Robert Lange <robert.lange@uni-leipzig.de>

module/fid/src/Controller/UserController.php

@@ -430,9 +430,7 @@ class UserController extends AbstractBase
         $viewModel = $this->createViewModel();
         $viewModel->setTemplate('fid/user/policy');
 
-        if (isset($_REQUEST['lbreferer'])) {
-            $viewModel->setVariable('backUrl', $_REQUEST['lbreferer']);
-        }
+        $this->setBackUrl($viewModel);
 
         return $viewModel;
     }
@@ -442,9 +440,7 @@ class UserController extends AbstractBase
         $viewModel = $this->createViewModel();
         $viewModel->setTemplate('fid/user/terms');
 
-        if (isset($_REQUEST['lbreferer'])) {
-            $viewModel->setVariable('backUrl', $_REQUEST['lbreferer']);
-        }
+        $this->setBackUrl($viewModel);
 
         return $viewModel;
     }
@@ -719,4 +715,23 @@ class UserController extends AbstractBase
         }
     }
 
+    /**
+     * @param ViewModel $viewModel
+     * @return bool
+     */
+    protected function setBackUrl(ViewModel $viewModel): bool
+    {
+        if (!empty($query = $this->getRequest()->getQuery()) && !empty($query->get('backUrl'))) {
+            $viewModel->setVariable('backUrl', $this->getRequest()->getQuery()->get('backUrl'));
+            return true;
+        }
+
+        if (isset($_REQUEST['lbreferer'])) {
+            $viewModel->setVariable('backUrl', $_REQUEST['lbreferer']);
+            return true;
+        }
+
+        return false;
+    }
+
 }