Block REST API for non-logged in users

block-rest-api.php

<?php

/**
 * Plugin Name: 608 Software - Block REST API
 * Plugin URI: https://608.software
 * Description: Block REST API for users that are not logged in
 * Author: 608 Software
 * Version: 1.0.2
 * Author URI: https://608.software
 * Text Domain: soes-block-rest-api
 * Domain Path: /languages
 * License: GPL-2.0+
 */

class SOES_Block_REST_API {

	function __construct() {
		add_action('init', array($this, 'action_init'));
	}

	public function action_init() {
		add_action( 'pre_get_posts', array($this, 'action_pre_get_posts' ));
		add_filter( 'rest_authentication_errors', array($this, 'filter_rest_authentication_errors' ));
	}

	function action_pre_get_posts( $query ) {
		// Do stuff here
	}

	function filter_rest_authentication_errors( $result ) {
		if ( ! empty( $result ) ) {
			return $result;
		}
		if ( ! is_user_logged_in() ) {
			return new WP_Error( 'rest_not_logged_in', 'You are not currently logged in.', array( 'status' => 401 ) );
		}
		return $result;
	}
	
}
new SOES_Block_REST_API();