Validate inet attributes are not multi attributes (#410)

* Validate inet attributes are not multi attributes

Ensure nobody create multi attribute of type inet. This is currently not supported and will cause crashes during runtime in the query executer.

Author: kofrezo

serveradmin/serverdb/forms.py

@@ -41,6 +41,12 @@ class Meta:
         fields = '__all__'
 
     def clean(self):
-        if self.cleaned_data['type'] != 'relation' and self.cleaned_data['target_servertype'] is not None:
+        attr_type = self.cleaned_data.get('type') or self.instance.type # New or existing attribute ?
+
+        if attr_type != 'relation' and self.cleaned_data.get('target_servertype') is not None:
             raise ValidationError('Attribute type must be relation when target servertype is selected!')
+
+        if attr_type == 'inet' and self.cleaned_data.get('multi') is True:
+            raise ValidationError('Multi attributes of type inet are not supported!')
+
         super().clean()