Caching WP REST API

readme.md

@@ -151,6 +151,7 @@ Standard features of the following plugins will be manipulated or extended.
 ### WP REST CACHE
 
 * Fade out Icon @ Admin Bar
+* ActivityPub Endpoints Caching
 
 ### wpRocket
 
@@ -215,6 +216,7 @@ This project is licensed under the GPL3 License.
 
 Release pending.
 
+* Added: Caching of ActivityPub Endpoints in WP REST API
 * Added: Fade out WB REST CACHE Icon @ Admin Bar
 * Added: Disable UpdraftPlus @ Admin Bar
 

unmus.php

@@ -47,6 +47,7 @@
 require_once('unmus_activitypub.php');
 require_once('unmus_widgets.php');
 require_once('unmus_visibility.php');
+require_once('unmus_cache.php');
 
 // Ensure that all required functions are available during setup
 require_once( ABSPATH . 'wp-admin/includes/upgrade.php');

unmus_cache.php

@@ -0,0 +1,171 @@
+<?php
+
+/**
+ * Caching
+ * 
+ * Rocket-related Caching, see unmus_rocket.php
+ * Following is referring to WP REST API (Plugin WP-REST-CACHE)
+ * 
+ * @package unmus
+ * @since 0.9
+ * 
+ * @link https://epiph.yt/en/blog/2025/activitypub-plugin-and-accidental-ddos/
+ */
+
+// Security: Stops code execution if WordPress is not loaded
+if (!defined('ABSPATH')) { exit; }
+
+// Import Caching Class from WP_Rest_Cache_Plugin
+use WP_Rest_Cache_Plugin\Includes\Caching\Caching;
+
+/**
+ * Get ActivityPub REST API Namespace
+ * 
+ * @since 0.9
+ * 
+ * @return string The ActivityPub REST API namespace
+ */
+
+ function unmus_cache_get_activitypub_restapi_namespace() {
+
+    $activitypub_api_namespace = 'activitypub/1.0';
+    return $activitypub_api_namespace;
+}
+
+/**
+ * Get ActivityPub endpoints to be cached
+ * 
+ * @since 0.9
+ * 
+ * @return array The ActivityPub endpoints to be cached
+ */
+
+function unmus_cache_get_activitypub_endpoints() {
+
+    $endpoints = [ unmus_cache_get_activitypub_restapi_namespace() => [
+        '',
+        'actors',
+        'application',
+        'collections',
+        'comments',
+        'inbox',
+        'interactions',
+        'nodeinfo',
+        'posts',
+        'users',
+        'webfinger'
+    ]];
+
+    return $endpoints;
+}
+
+/**
+ * Add ActivityPub Endpoints to Cache
+ * 
+ * @since 0.9
+ * 
+ * @param array Endpoints that are allowed to be cached
+ * @return array Allowed Endpoints extended with ActivityPub
+ */
+
+function unmus_cache_add_activitypub_endpoints( $allowed_endpoints ) {
+
+    $activitypub_api_namespace = unmus_cache_get_activitypub_restapi_namespace();
+    $endpoints = unmus_cache_get_activitypub_endpoints();
+
+    if(!isset($allowed_endpoints[$activitypub_api_namespace])) {
+        $allowed_endpoints[$activitypub_api_namespace] = $endpoints[$activitypub_api_namespace];
+    }
+
+    return $allowed_endpoints;
+
+}
+add_filter( 'wp_rest_cache/allowed_endpoints', 'unmus_cache_add_activitypub_endpoints', 10, 1);
+
+/**
+ * Is ActivityPub Endpoint
+ *
+ * @param string $uri URI to test
+ * @return bool Whether the current endpoint is an ActivityPub endpoint
+ */
+
+function unmus_is_activitypub_endpoint( string $uri ) :bool {
+
+    $search = '/' . unmus_cache_get_activitypub_restapi_namespace() . '/';
+
+    return \str_contains( $uri, $search ) || \str_contains( $uri, 'rest_route=' . \rawurlencode( $search ) );
+}
+
+/**
+ * Determine Object Type
+ * 
+ * @since 0.9
+ * 
+ * @param string $object_type Object type
+ * @param string $cache_key Object key
+ * @param mixed	$data Data to cache
+ * @param string $uri Request URI
+ * @return string Updated object type
+ */
+
+function unmus_cache_determine_object_type( $object_type, $cache_key, $data, $uri ) {
+
+    if (unmus_is_activitypub_endpoint( $uri ) ) {
+        $object_type = 'ActivityPub';
+        return $object_type;
+    }
+}
+add_filter( 'wp_rest_cache/determine_object_type', 'unmus_cache_determine_object_type', 10, 4 );
+
+/**
+ * Reset Cache by Transition Post Status
+ *
+ * @since 0.9
+ * 
+ * @param string $new_status New post status
+ * @param string $old_status Old post status
+ * @param \WP_Post $post Post object
+ */
+
+function unmus_cache_reset_by_transition_post_status( string $new_status, string $old_status, \WP_Post $post ): void {
+
+    if ( $new_status !== 'publish' && $old_status !== 'publish' ) {
+        return;
+    }
+
+    $supported_post_types = (array) \get_option( 'activitypub_support_post_types', [] );
+
+    if ( ! \in_array( $post->post_type, $supported_post_types, true ) ) {
+        return;
+    }
+
+    if ( ! \class_exists( 'WP_Rest_Cache_Plugin\Includes\Caching\Caching' ) ) {
+        return;
+    }
+
+    Caching::get_instance()->delete_object_type_caches( 'ActivityPub' );
+}
+add_action( 'transition_post_status', 'unmus_cache_reset_by_transition_post_status', 10, 3 );
+
+/**
+ * Set whether the cache represents a single item.
+ *
+ * Always return false for ActivityPub endpoints, 
+ * since cache entries cannot be flushed otherwise.
+ *
+ * @param	bool	$is_single Whether the current cache represents a single item
+ * @param	mixed	$data Data to cache
+ * @param	string	$uri Request URI
+ * @return	bool Whether the cache represents a single item
+ */
+
+function set_is_single_item( bool $is_single, mixed $data, string $uri ): bool {
+    if ( unmus_is_activitypub_endpoint( $uri ) ) {
+        return false;
+    }
+
+    return $is_single;
+}
+add_filter( 'wp_rest_cache/is_single_item', 'set_is_single_item' , 10, 3 );
+
+?>