Add a safety check about expressions and tokens

lizmap_server/core.py

@@ -392,3 +392,19 @@ def _server_feature_id_expression(feature_id: str, pk_attributes: list, fields:
         expression += QgsExpression.createFieldEqualityExpression(field_name, pk_values[i])
 
     return expression
+
+
+def qgis_expression(text: str, only_fields: bool = False) -> Tuple[QgsExpression, bool]:
+    """ Get the QGIS expression. """
+    exp = QgsExpression(text)
+    if only_fields:
+        functions = exp.referencedFunctions()
+        if len(functions) >= 1:
+            logger = Logger()
+            logger.critical(
+                f"The expression below\n{text}\ncontains some functions : {','.join(functions)}\n"
+                f"Returning an empty expression."
+            )
+            return QgsExpression(''), False
+
+    return exp, True

lizmap_server/expression_service.py

@@ -34,6 +34,7 @@
     get_lizmap_groups,
     get_lizmap_user_login,
     get_server_fid,
+    qgis_expression,
     write_json_response,
 )
 from lizmap_server.exception import ExpressionServiceError
@@ -187,7 +188,7 @@ def evaluate(params: Dict[str, str], response: QgsServerResponse, project: QgsPr
         elif isinstance(exp_json, dict):
             exp_items = exp_json.items()
         for k, e in exp_items:
-            exp = QgsExpression(e)
+            exp = qgis_expression(e)[0]
             exp.setGeomCalculator(da)
             exp.setDistanceUnits(project.distanceUnits())
             exp.setAreaUnits(project.areaUnits())
@@ -716,7 +717,7 @@ def get_feature_with_form_scope(
         da.setEllipsoid(project.ellipsoid())
 
         # Get filter expression
-        exp_f = QgsExpression(exp_filter)
+        exp_f = qgis_expression(exp_filter)[0]
         exp_f.setGeomCalculator(da)
         exp_f.setDistanceUnits(project.distanceUnits())
         exp_f.setAreaUnits(project.areaUnits())
@@ -840,7 +841,7 @@ def virtualFields(params: Dict[str, str], response: QgsServerResponse, project:
         exp_map = {}
         exp_parser_errors = []
         for k, e in vir_json.items():
-            exp = QgsExpression(e)
+            exp = qgis_expression(e)[0]
             exp.setGeomCalculator(da)
             exp.setDistanceUnits(project.distanceUnits())
             exp.setAreaUnits(project.areaUnits())
@@ -868,7 +869,7 @@ def virtualFields(params: Dict[str, str], response: QgsServerResponse, project:
         # get filter
         req_filter = params.get('FILTER', '')
         if req_filter:
-            req_exp = QgsExpression(req_filter)
+            req_exp = qgis_expression(req_filter)[0]
             req_exp.setGeomCalculator(da)
             req_exp.setDistanceUnits(project.distanceUnits())
             req_exp.setAreaUnits(project.areaUnits())

lizmap_server/get_feature_info.py

@@ -24,7 +24,7 @@
 )
 from qgis.server import QgsServerFilter, QgsServerProjectUtils
 
-from lizmap_server.core import find_vector_layer, server_feature_id_expression
+from lizmap_server.core import find_vector_layer, server_feature_id_expression, qgis_expression
 from lizmap_server.logger import Logger, exception_handler
 from lizmap_server.tools import to_bool
 from lizmap_server.tooltip import Tooltip
@@ -230,7 +230,7 @@ def responseComplete(self):
 
                 expression = server_feature_id_expression(result.feature_id, result.layer.dataProvider())
                 if expression:
-                    expression_request = QgsFeatureRequest(QgsExpression(expression))
+                    expression_request = QgsFeatureRequest(qgis_expression(expression)[0])
                     if not geometry_result:
                         expression_request.setFlags(QgsFeatureRequest.NoGeometry)
                     feature = QgsFeature()

test/test_server_core.py

@@ -12,6 +12,7 @@
     get_lizmap_config,
     get_lizmap_layer_login_filter,
     get_lizmap_layers_config,
+    qgis_expression,
 )
 from lizmap_server.get_feature_info import GetFeatureInfoFilter
 from lizmap_server.tools import to_bool
@@ -266,3 +267,9 @@ def test_feature_id_expression(self):
             "\"field_1\" = '1' AND \"field_2\" = '2'",
             _server_feature_id_expression("1@@2", ['field_1', 'field_2'], fields),
         )
+
+    def test_expression(self):
+        """ Test about expressions and tokens. """
+        self.assertTrue(qgis_expression('"hi"')[1])
+        self.assertTrue(qgis_expression('hi')[1])
+        self.assertTrue(qgis_expression('lower("hi")')[1])