Basic regex validation on community rule entry form. Fixes #2928. Commit ready for merge.

- Legacy-Id: 17490

ietf/community/forms.py

@@ -4,6 +4,8 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+import re
+
 from django import forms
 from django.db.models import Q
 
@@ -94,7 +96,12 @@ class SearchRuleForm(forms.ModelForm):
             f.required = True
 
     def clean_text(self):
-        return self.cleaned_data["text"].strip().lower() # names are always lower case
+        candidate_text = self.cleaned_data["text"].strip().lower() # names are always lower case
+        try:
+            re.compile(candidate_text)
+        except re.error as e:
+            raise forms.ValidationError(str(e))
+        return candidate_text
 
 
 class SubscriptionForm(forms.ModelForm):