Android Question httputils: Detect where a php script is called from?

if ( isset($_POST['AUTH']) ) {
    // verify the authentication, re-request if necessary - we expire an AUTH key from time to time
    // if the key is idle for too long, or if it's used from a different IP address
   
    $authQ = $blufDB->query(sprintf("SELECT memberid, lastIP, UNIX_TIMESTAMP(lastAuth) AS lastAuth, appid FROM apiAuth WHERE hash = '%s'",$blufDB->real_escape_string($_POST['AUTH']))) ;
    if ( $authQ->num_rows != 1 ) {
        // the user has been logged out
        send_api_response('reauth','','Session expired or invalid','') ;
        // api_error('Authorisation error') ;
        exit ;
    } else {
       
        $auth = $authQ->fetch_assoc() ;
       
        if ( $_SERVER['REMOTE_ADDR'] != $auth['lastIP'] ) {
            // IP address changed, demand a reauth
            send_api_response('reauth','','IP changed address change detected','') ;
            exit ;
        } elseif ( $auth['lastAuth'] < (time() - ( 60 * $expiryTime )) ) {
            // no request within expiry limit
            send_api_response('reauth','','Auth timeout exceeded','') ;
            exit ;
        } else {
            // update the lastAuth timestamp           
            $blufDB->query(sprintf("UPDATE apiAuth SET lastAuth = NOW() WHERE hash = '%s'",$blufDB->real_escape_string($_POST['AUTH']))) ;
        }
    }
}