activitypub / includes / rest / class-proxy-controller.php

class-proxy-controller.php in ActivityPub 8.2.1, at includes/rest/class-proxy-controller.php

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1	<?php
2	/**
3	* Proxy Controller file.
4	*
5	* Implements the proxyUrl endpoint for C2S clients to fetch remote ActivityPub objects.
6	*
7	* @package Activitypub
8	* @see https://www.w3.org/wiki/ActivityPub/Primer/proxyUrl_endpoint
9	*/
10
11	namespace Activitypub\Rest;
12
13	use Activitypub\Collection\Remote_Actors;
14	use Activitypub\Http;
15
16	use function Activitypub\is_actor;
17
18	/**
19	* Proxy Controller.
20	*
21	* Provides a bridge between C2S OAuth authentication and S2S HTTP Signature authentication.
22	* Allows C2S clients to fetch remote ActivityPub objects through their home server.
23	*/
24	class Proxy_Controller extends \WP_REST_Controller {
25	use Event_Stream;
26	use Verification;
27
28	/**
29	* The namespace of this controller's route.
30	*
31	* @var string
32	*/
33	protected $namespace = ACTIVITYPUB_REST_NAMESPACE;
34
35	/**
36	* The base of this controller's route.
37	*
38	* @var string
39	*/
40	protected $rest_base = 'proxy';
41
42	/**
43	* Register routes.
44	*/
45	public function register_routes() {
46	\register_rest_route(
47	$this->namespace,
48	'/' . $this->rest_base,
49	array(
50	array(
51	'methods' => \WP_REST_Server::CREATABLE,
52	'callback' => array( $this, 'create_item' ),
53	'permission_callback' => array( $this, 'verify_authentication' ),
54	'args' => array(
55	'id' => array(
56	'description' => 'The URI of the remote ActivityPub object to fetch.',
57	'type' => 'string',
58	'required' => true,
59	'sanitize_callback' => array( $this, 'sanitize_url' ),
60	'validate_callback' => array( $this, 'validate_url' ),
61	),
62	),
63	),
64	'schema' => array( $this, 'get_item_schema' ),
65	)
66	);
67
68	\register_rest_route(
69	$this->namespace,
70	'/' . $this->rest_base . '/stream',
71	array(
72	array(
73	'methods' => \WP_REST_Server::READABLE,
74	'callback' => array( $this, 'get_stream' ),
75	'permission_callback' => array( $this, 'get_stream_permissions_check' ),
76	'args' => array(
77	'id' => array(
78	'description' => 'The remote object ID (URI) whose eventStream to proxy.',
79	'type' => 'string',
80	'format' => 'uri',
81	'required' => true,
82	'sanitize_callback' => array( $this, 'sanitize_url' ),
83	'validate_callback' => array( $this, 'validate_url' ),
84	),
85	),
86	),
87	)
88	);
89	}
90
91	/**
92	* Sanitizes the URL parameter.
93	*
94	* @see https://developer.wordpress.org/reference/functions/sanitize_url/
95	*
96	* @param string $url The urlencoded URL to sanitize.
97	* @return string The sanitized URL.
98	*/
99	public function sanitize_url( $url ) {
100	// Decode and sanitize the URL.
101	return sanitize_url( urldecode( $url ) );
102	}
103	/**
104	* Validate the URL parameter.
105	*
106	* Uses wp_http_validate_url() which blocks local/private IPs and restricts ports.
107	*
108	* @see https://developer.wordpress.org/reference/functions/wp_http_validate_url/
109	*
110	* @param string $url The URL to validate.
111	* @return bool True if valid, false otherwise.
112	*/
113	public function validate_url( $url ) {
114	// Decode the url.
115	$decoded_url = urldecode( $url );
116
117	// Must be HTTPS.
118	if ( 'https' !== \wp_parse_url( $decoded_url, PHP_URL_SCHEME ) ) {
119	return false;
120	}
121
122	// Use WordPress built-in validation (blocks local IPs, restricts ports).
123	return (bool) \wp_http_validate_url( $decoded_url );
124	}
125
126	/**
127	* Fetch a remote ActivityPub object via the proxy.
128	*
129	* @see https://www.w3.org/wiki/ActivityPub/Primer/proxyUrl_endpoint
130	*
131	* @param \WP_REST_Request $request Full details about the request.
132	* @return \WP_REST_Response\|\WP_Error Response object on success, WP_Error on failure.
133	*/
134	public function create_item( $request ) {
135	// Rate-limit proxy requests (max 30 per minute per user).
136	$user_id = \get_current_user_id();
137	$transient_key = 'ap_proxy_' . $user_id;
138	$count = (int) \get_transient( $transient_key );
139
140	if ( $count >= 30 ) {
141	return new \WP_Error(
142	'activitypub_rate_limit',
143	\__( 'Too many proxy requests. Please try again later.', 'activitypub' ),
144	array( 'status' => 429 )
145	);
146	}
147
148	\set_transient( $transient_key, $count + 1, MINUTE_IN_SECONDS );
149
150	$url = $request->get_param( 'id' );
151
152	// Try to fetch as an actor first using Remote_Actors which handles caching.
153	$post = Remote_Actors::fetch_by_various( $url );
154
155	if ( ! \is_wp_error( $post ) ) {
156	$actor = Remote_Actors::get_actor( $post );
157
158	if ( ! \is_wp_error( $actor ) ) {
159	$response = new \WP_REST_Response( $actor->to_array(), 200 );
160	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
161
162	return $response;
163	}
164	}
165
166	// Fall back to fetching as a generic object.
167	$object = Http::get_remote_object( $url );
168
169	if ( \is_wp_error( $object ) ) {
170	return new \WP_Error(
171	'activitypub_fetch_failed',
172	\__( 'Failed to fetch the remote object.', 'activitypub' ),
173	array( 'status' => 502 )
174	);
175	}
176
177	// If it's an actor, store it for future use.
178	if ( is_actor( $object ) ) {
179	Remote_Actors::upsert( $object );
180	}
181
182	$response = new \WP_REST_Response( $object, 200 );
183	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
184
185	return $response;
186	}
187
188	/**
189	* Get the schema for the proxy endpoint.
190	*
191	* @return array Schema array.
192	*/
193	public function get_item_schema() {
194	return array(
195	'$schema' => 'http://json-schema.org/draft-04/schema#',
196	'title' => 'proxy',
197	'type' => 'object',
198	'properties' => array(
199	'id' => array(
200	'description' => \__( 'The URI of the remote ActivityPub object.', 'activitypub' ),
201	'type' => 'string',
202	'format' => 'uri',
203	'context' => array( 'view' ),
204	),
205	),
206	);
207	}
208
209	/**
210	* Proxy a remote eventStream.
211	*
212	* Fetches the remote object to discover its eventStream URL,
213	* then opens a streaming connection and relays SSE events.
214	*
215	* @param \WP_REST_Request $request Full details about the request.
216	*
217	* @return \WP_Error\|void WP_Error on failure, exits on success.
218	*/
219	public function get_stream( $request ) {
220	$remote_id = $request->get_param( 'id' );
221
222	$object = Http::get_remote_object( $remote_id );
223
224	if ( \is_wp_error( $object ) ) {
225	return new \WP_Error(
226	'activitypub_proxy_fetch_failed',
227	\__( 'Failed to fetch the remote object.', 'activitypub' ),
228	array( 'status' => 502 )
229	);
230	}
231
232	$stream_url = isset( $object['eventStream'] ) ? $object['eventStream'] : null;
233
234	if ( ! $stream_url ) {
235	return new \WP_Error(
236	'activitypub_no_event_stream',
237	\__( 'The remote object does not advertise an eventStream.', 'activitypub' ),
238	array( 'status' => 404 )
239	);
240	}
241
242	if ( ! $this->validate_url( $stream_url ) ) {
243	return new \WP_Error(
244	'activitypub_invalid_event_stream',
245	\__( 'The remote eventStream URL is not valid.', 'activitypub' ),
246	array( 'status' => 400 )
247	);
248	}
249
250	$this->relay_remote_stream( $stream_url );
251	}
252	}
253