LDAP search filter should not be an empty string

authserv/ldap_model.py

@@ -57,7 +57,7 @@ class UserDb(model.UserDb):
             #
             if 'dn' in ldap_params:
                 base = ldap_params['dn'].replace('%s', escape_dn_chars(username))
-                filt = ldap_params.get('filter', '').replace('%s', escape_filter_chars(username))
+                filt = ldap_params.get('filter', '(objectClass=*)').replace('%s', escape_filter_chars(username))
                 scope = ldap.SCOPE_BASE
             else:
                 base = ldap_params['base'].replace('%s', escape_dn_chars(username))