public function groupUserMembershipsFromDn($user) {

    if (!$this->groupDeriveFromDn || !$this->groupDeriveFromDnAttr) {
      return FALSE;
    }
    elseif ($user_ldap_entry = $this->userUserToExistingLdapEntry($user)) {
      return ldap_servers_get_all_rdn_values_from_dn($user_ldap_entry['dn'], $this->groupDeriveFromDnAttr);
    }
    else {
      return FALSE;
    }

  }