Basic Announce support

includes/class-handler.php

@@ -1,6 +1,7 @@
 <?php
 namespace Activitypub;
 
+use Activitypub\Handler\Announce;
 use Activitypub\Handler\Create;
 use Activitypub\Handler\Delete;
 use Activitypub\Handler\Follow;
@@ -22,6 +23,7 @@ public static function init() {
 	 * Register handlers.
 	 */
 	public static function register_handlers() {
+		Announce::init();
 		Create::init();
 		Delete::init();
 		Follow::init();

includes/class-http.php

@@ -154,4 +154,98 @@ public static function is_tombstone( $url ) {
 	public static function generate_cache_key( $url ) {
 		return 'activitypub_http_' . \md5( $url );
 	}
+
+	/**
+	 * Requests the Data from the Object-URL or Object-Array
+	 *
+	 * @param array|string $url_or_object The Object or the Object URL.
+	 * @param bool         $cached        If the result should be cached.
+	 *
+	 * @return array|WP_Error The Object data as array or WP_Error on failure.
+	 */
+	public static function get_remote_object( $url_or_object, $cached = true ) {
+		if ( is_array( $url_or_object ) ) {
+			if ( array_key_exists( 'id', $url_or_object ) ) {
+				$url = $url_or_object['id'];
+			} elseif ( array_key_exists( 'url', $url_or_object ) ) {
+				$url = $url_or_object['url'];
+			} else {
+				return new WP_Error(
+					'activitypub_no_valid_actor_identifier',
+					\__( 'The "actor" identifier is not valid', 'activitypub' ),
+					array(
+						'status' => 404,
+						'object' => $url_or_object,
+					)
+				);
+			}
+		} else {
+			$url = $url_or_object;
+		}
+
+		if ( preg_match( '/^@?' . ACTIVITYPUB_USERNAME_REGEXP . '$/i', $url ) ) {
+			$url = Webfinger::resolve( $url );
+		}
+
+		if ( ! $url ) {
+			return new WP_Error(
+				'activitypub_no_valid_actor_identifier',
+				\__( 'The "actor" identifier is not valid', 'activitypub' ),
+				array(
+					'status' => 404,
+					'object' => $url,
+				)
+			);
+		}
+
+		if ( is_wp_error( $url ) ) {
+			return $url;
+		}
+
+		$transient_key = self::generate_cache_key( $url );
+
+		// only check the cache if needed.
+		if ( $cached ) {
+			$data = \get_transient( $transient_key );
+
+			if ( $data ) {
+				return $data;
+			}
+		}
+
+		if ( ! \wp_http_validate_url( $url ) ) {
+			return new WP_Error(
+				'activitypub_no_valid_object_url',
+				\__( 'The "object" is/has no valid URL', 'activitypub' ),
+				array(
+					'status' => 400,
+					'object' => $url,
+				)
+			);
+		}
+
+		$response = self::get( $url );
+
+		if ( \is_wp_error( $response ) ) {
+			return $response;
+		}
+
+		$data = \wp_remote_retrieve_body( $response );
+		$data = \json_decode( $data, true );
+
+		if ( ! $data ) {
+			return new WP_Error(
+				'activitypub_invalid_json',
+				\__( 'No valid JSON data', 'activitypub' ),
+				array(
+					'status' => 400,
+					'object' => $url,
+				)
+			);
+		}
+
+		\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
+
+		return $data;
+	}
 }

includes/handler/class-announce.php

@@ -0,0 +1,69 @@
+<?php
+namespace Activitypub\Handler;
+
+use Activitypub\Http;
+
+use function Activitypub\is_activity_public;
+
+/**
+ * Handle Create requests
+ */
+class Announce {
+	/**
+	 * Initialize the class, registering WordPress hooks
+	 */
+	public static function init() {
+		\add_action(
+			'activitypub_inbox_announce',
+			array( self::class, 'handle_announce' ),
+			10,
+			3
+		);
+	}
+
+	/**
+	 * Handles "Announce" requests
+	 *
+	 * @param array                $array    The activity-object
+	 * @param int                  $user_id  The id of the local blog-user
+	 * @param Activitypub\Activity $activity The activity object
+	 *
+	 * @return void
+	 */
+	public static function handle_announce( $array, $user_id, $activity = null ) { // phpcs:ignore Universal.NamingConventions.NoReservedKeywordParameterNames.arrayFound
+		if ( ACTIVITYPUB_DISABLE_INCOMING_INTERACTIONS ) {
+			return;
+		}
+
+		if ( ! isset( $array['object'] ) ) {
+			return;
+		}
+
+		// check if Activity is public or not
+		if ( ! is_activity_public( $array ) ) {
+			// @todo maybe send email
+			return;
+		}
+
+		// @todo save the `Announce`-Activity itself
+
+		if ( is_string( $array['object'] ) ) {
+			$object = Http::get_remote_object( $array['object'] );
+		} else {
+			$object = $array['object'];
+		}
+
+		if ( ! $object || is_wp_error( $object ) ) {
+			return;
+		}
+
+		if ( ! isset( $object['type'] ) ) {
+			return;
+		}
+
+		$type = \strtolower( $object['type'] );
+
+		\do_action( 'activitypub_inbox', $object, $user_id, $type, $activity );
+		\do_action( "activitypub_inbox_{$type}", $object, $user_id, $activity );
+	}
+}