Make sure all inverse references are removed on node deletion

Iterating over the references list and deleting inside the same list
resulted in dangling inverse references if nodes where deleted.

Fix this by iterating over a copy of the references list.

Author: helmut-jacob

opcua/server/address_space.py

@@ -330,7 +330,7 @@ def _delete_node(self, item, user):
 
         if item.DeleteTargetReferences:
             for elem in self._aspace.keys():
-                for rdesc in self._aspace[elem].references:
+                for rdesc in self._aspace[elem].references[:]:
                     if rdesc.NodeId == item.NodeId:
                         self._aspace[elem].references.remove(rdesc)
 

tests/tests_common.py

@@ -118,6 +118,27 @@ def test_delete_nodes(self):
         childs = fold.get_children()
         self.assertNotIn(var, childs)
 
+
+    def test_delete_nodes_with_inverse_references(self):
+        obj = self.opc.get_objects_node()
+        fold = obj.add_folder(2, "FolderToDelete")
+        var = fold.add_variable(2, "VarToDelete", 9.1)
+        var2 = fold.add_variable(2, "VarWithReference", 9.2)
+        childs = fold.get_children()
+        self.assertIn(var, childs)
+        self.assertIn(var2, childs)
+        # add two references to var, this includes adding the inverse references to var2
+        var.add_reference(var2.nodeid, reftype=ua.ObjectIds.HasDescription, forward=True, bidirectional=True)
+        var.add_reference(var2.nodeid, reftype=ua.ObjectIds.HasEffect, forward=True, bidirectional=True)
+        self.opc.delete_nodes([var])
+        childs = fold.get_children()
+        assert var not in childs
+        has_desc_refs = var2.get_referenced_nodes(refs=ua.ObjectIds.HasDescription, direction=ua.BrowseDirection.Inverse)
+        assert len(has_desc_refs) == 0
+        has_effect_refs = var2.get_referenced_nodes(refs=ua.ObjectIds.HasEffect, direction=ua.BrowseDirection.Inverse)
+        assert len(has_effect_refs) == 0
+
+
     def test_delete_nodes_recursive(self):
         obj = self.opc.get_objects_node()
         fold = obj.add_folder(2, "FolderToDeleteR")