LdapRepository: Add method isAmbiguous()

refs #9950

library/Icinga/Repository/LdapRepository.php

@@ -42,6 +42,15 @@ abstract class LdapRepository extends Repository
         'groupofuniquenames'    => 'groupOfUniqueNames'
     );
 
+    /**
+     * Object attributes whose value is not distinguished name
+     *
+     * @var array
+     */
+    protected $ambiguousAttributes = array(
+        'posixGroup' => 'memberUid'
+    );
+
     /**
      * Create a new LDAP repository object
      *
@@ -68,4 +77,17 @@ abstract class LdapRepository extends Repository
 
         return $name;
     }
-}
+
+    /**
+     * Return whether the given object attribute's value is not a distinguished name
+     *
+     * @param   string  $objectClass
+     * @param   string  $attributeName
+     *
+     * @return  bool
+     */
+    protected function isAmbiguous($objectClass, $attributeName)
+    {
+        return isset($this->ambiguousAttributes[$objectClass][$attributeName]);
+    }
+}