wordpress redirect main site

function redirect_to_new_site()
{
    if ( !is_main_site() || is_admin() || is_user_logged_in() || $GLOBALS['pagenow'] === 'wp-login.php' ) {
        return;
    } else {
        exit( wp_redirect( 'http://engineering.utm.my/mechanical/', 301 ) );
    }
}
add_action( 'init', 'redirect_to_new_site' );