activitypub / includes / handler / class-follow.php

class-follow.php in ActivityPub trunk, at includes/handler/class-follow.php

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1	<?php
2	/**
3	* Follow handler file.
4	*
5	* @package Activitypub
6	*/
7
8	namespace Activitypub\Handler;
9
10	use Activitypub\Activity\Activity;
11	use Activitypub\Application;
12	use Activitypub\Collection\Actors;
13	use Activitypub\Collection\Followers;
14	use Activitypub\Collection\Remote_Actors;
15	use Activitypub\Http;
16
17	use function Activitypub\add_to_outbox;
18	use function Activitypub\object_to_uri;
19
20	/**
21	* Handle Follow requests.
22	*/
23	class Follow {
24	/**
25	* Initialize the class, registering WordPress hooks.
26	*/
27	public static function init() {
28	\add_action( 'activitypub_inbox_follow', array( self::class, 'handle_follow' ), 10, 2 );
29	\add_action( 'activitypub_handled_follow', array( self::class, 'queue_accept' ), 10, 4 );
30
31	// The Application actor cannot be followed; explicitly reject such Follows so they don't sit "pending" on the remote instance forever.
32	\add_action( 'activitypub_inbox_shared_follow', array( self::class, 'reject_application_follow' ), 10, 2 );
33	}
34
35	/**
36	* Handle "Follow" requests.
37	*
38	* @param array $activity The activity object.
39	* @param int\|int[] $user_ids The user ID(s).
40	*/
41	public static function handle_follow( $activity, $user_ids ) {
42	// Extract the user ID (follow requests are always for a single user).
43	$user_id = \is_array( $user_ids ) ? \reset( $user_ids ) : $user_ids;
44
45	// Check if the actor already follows the user.
46	$already_following = false;
47	$remote_actor = Remote_Actors::get_by_uri( $activity['actor'] );
48	if ( ! \is_wp_error( $remote_actor ) ) {
49	$already_following = Followers::follows( $remote_actor->ID, $user_id );
50	}
51
52	// Save follower if not already following.
53	if ( $already_following ) {
54	$success = false;
55	} else {
56	$remote_actor = Followers::add( $user_id, $activity['actor'] );
57	$success = ! \is_wp_error( $remote_actor );
58
59	if ( $success ) {
60	$remote_actor = \get_post( $remote_actor );
61	}
62	}
63
64	/**
65	* Fires after a new follower has been added.
66	*
67	* @deprecated 7.5.0 Use "activitypub_handled_follow" instead.
68	*
69	* @param string $actor The URL of the actor (follower) who initiated the follow.
70	* @param array $activity The complete activity data of the follow request.
71	* @param int $user_id The ID of the WordPress user being followed.
72	* @param \WP_Post\|\WP_Error $remote_actor The Actor object containing the new follower's data.
73	*/
74	\do_action_deprecated( 'activitypub_followers_post_follow', array( $activity['actor'], $activity, $user_id, $remote_actor ), '7.5.0', 'activitypub_handled_follow' );
75
76	/**
77	* Fires after a Follow activity has been handled.
78	*
79	* @param array $activity The ActivityPub activity data.
80	* @param int[] $user_ids The local user IDs.
81	* @param bool $success True on success, false otherwise.
82	* @param \WP_Post\|\WP_Error $remote_actor The remote actor/follower, or WP_Error if failed.
83	*/
84	\do_action( 'activitypub_handled_follow', $activity, (array) $user_ids, $success, $remote_actor );
85	}
86
87	/**
88	* Send Accept response.
89	*
90	* @param array $activity_object The ActivityPub activity data.
91	* @param int\|int[] $user_ids The local user IDs.
92	* @param bool $success True on success, false otherwise.
93	* @param \WP_Post\|\WP_Error $remote_actor The remote actor/follower, or WP_Error if failed.
94	*/
95	public static function queue_accept( $activity_object, $user_ids, $success, $remote_actor ) {
96	if ( \is_wp_error( $remote_actor ) ) {
97	// Impossible to send a "Reject" because we can not get the Remote-Inbox.
98	return;
99	}
100
101	// Extract the user ID from the array (follow requests are always for a single user).
102	$user_id = \is_array( $user_ids ) ? \reset( $user_ids ) : $user_ids;
103
104	$actor = $activity_object['actor'];
105
106	// Only send minimal data.
107	$activity_object = \array_intersect_key(
108	$activity_object,
109	array(
110	'id' => 1,
111	'type' => 1,
112	'actor' => 1,
113	'object' => 1,
114	)
115	);
116
117	$activity = new Activity();
118	$activity->set_type( 'Accept' );
119	$activity->set_actor( Actors::get_by_id( $user_id )->get_id() );
120	$activity->set_object( $activity_object );
121	$activity->set_to( array( $actor ) );
122
123	add_to_outbox( $activity, null, $user_id, ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE );
124	}
125
126	/**
127	* Reject Follow requests aimed at the Application actor.
128	*
129	* The Application advertises `manuallyApprovesFollowers` but is not followable,
130	* so an explicit Reject is the only way a remote follow request gets resolved.
131	* The Reject is sent directly instead of through the Outbox, which only
132	* dispatches for real actors, and is signed with the Application key.
133	*
134	* @since 9.1.0
135	*
136	* @param array $activity The Follow activity data.
137	* @param int[] $user_ids The local recipient IDs the inbox resolved.
138	*/
139	public static function reject_application_follow( $activity, $user_ids ) {
140	// A resolved recipient means the Follow targets a real actor, not the Application.
141	if ( ! empty( $user_ids ) ) {
142	return;
143	}
144
145	if ( empty( $activity['object'] ) \|\| ! Application::is_application_resource( object_to_uri( $activity['object'] ) ) ) {
146	return;
147	}
148
149	$actor = object_to_uri( $activity['actor'] );
150	$remote_actor = Remote_Actors::fetch_by_uri( $actor );
151
152	if ( \is_wp_error( $remote_actor ) ) {
153	return;
154	}
155
156	$inbox = \get_post_meta( $remote_actor->ID, '_activitypub_inbox', true );
157
158	if ( ! $inbox ) {
159	return;
160	}
161
162	// Only send minimal data.
163	$origin_activity = \array_intersect_key(
164	$activity,
165	array(
166	'id' => 1,
167	'type' => 1,
168	'actor' => 1,
169	'object' => 1,
170	)
171	);
172
173	$reject = new Activity();
174	$reject->set_type( 'Reject' );
175	$reject->set_id( Application::get_id() . '#reject-' . \md5( \wp_json_encode( $origin_activity ) ) );
176	$reject->set_actor( Application::get_id() );
177	$reject->set_object( $origin_activity );
178	$reject->set_to( array( $actor ) );
179
180	Http::post( $inbox, $reject->to_json(), null );
181	}
182	}
183