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

class-proxy-controller.php in ActivityPub 9.0.0, 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	use Activitypub\Webfinger;
16
17	use function Activitypub\is_actor;
18
19	/**
20	* Proxy Controller.
21	*
22	* Provides a bridge between C2S OAuth authentication and S2S HTTP Signature authentication.
23	* Allows C2S clients to fetch remote ActivityPub objects through their home server.
24	*/
25	class Proxy_Controller extends \WP_REST_Controller {
26	use Event_Stream;
27	use Verification;
28
29	/**
30	* The namespace of this controller's route.
31	*
32	* @var string
33	*/
34	protected $namespace = ACTIVITYPUB_REST_NAMESPACE;
35
36	/**
37	* The base of this controller's route.
38	*
39	* @var string
40	*/
41	protected $rest_base = 'proxy';
42
43	/**
44	* Register routes.
45	*/
46	public function register_routes() {
47	\register_rest_route(
48	$this->namespace,
49	'/' . $this->rest_base,
50	array(
51	array(
52	'methods' => \WP_REST_Server::CREATABLE,
53	'callback' => array( $this, 'create_item' ),
54	'permission_callback' => array( $this, 'verify_authentication' ),
55	'args' => array(
56	'id' => array(
57	'description' => 'The remote ActivityPub object to fetch: an HTTPS URL or an acct identifier (`user@host`, `@user@host`, or `acct:user@host`).',
58	'type' => 'string',
59	'required' => true,
60	'sanitize_callback' => array( $this, 'sanitize_url' ),
61	'validate_callback' => array( $this, 'validate_url' ),
62	),
63	),
64	),
65	'schema' => array( $this, 'get_item_schema' ),
66	)
67	);
68
69	\register_rest_route(
70	$this->namespace,
71	'/' . $this->rest_base . '/stream',
72	array(
73	array(
74	'methods' => \WP_REST_Server::READABLE,
75	'callback' => array( $this, 'get_stream' ),
76	'permission_callback' => array( $this, 'get_stream_permissions_check' ),
77	'args' => array(
78	'id' => array(
79	'description' => 'The remote actor identifier (URL or WebFinger acct) whose eventStream to proxy.',
80	'type' => 'string',
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	* Sanitize the `id` parameter.
93	*
94	* Accepts either an HTTPS URL or an acct identifier (`user@host`,
95	* `@user@host`, or `acct:user@host`). Acct identifiers are returned
96	* as-is; URLs are run through `sanitize_url()`. Matches the dual-shape
97	* contract of `Remote_Actors::fetch_by_various()`.
98	*
99	* @see https://developer.wordpress.org/reference/functions/sanitize_url/
100	*
101	* @param string $url The urlencoded URL or acct identifier to sanitize.
102	* @return string The sanitized value.
103	*/
104	public function sanitize_url( $url ) {
105	$decoded = \urldecode( $url );
106
107	if ( Webfinger::is_acct( $decoded ) ) {
108	return $decoded;
109	}
110
111	return \sanitize_url( $decoded );
112	}
113
114	/**
115	* Validate the `id` parameter.
116	*
117	* Accepts either an HTTPS URL (validated via `wp_http_validate_url()`,
118	* which blocks local/private IPs and restricts ports) or an acct
119	* identifier in any of the forms accepted by `Webfinger::is_acct()`:
120	* `user@host`, `@user@host`, or `acct:user@host`. Matches the
121	* dual-shape contract of `Remote_Actors::fetch_by_various()`.
122	*
123	* @see https://developer.wordpress.org/reference/functions/wp_http_validate_url/
124	*
125	* @param string $url The URL or acct identifier to validate.
126	* @return bool True if valid, false otherwise.
127	*/
128	public function validate_url( $url ) {
129	$decoded_url = \urldecode( $url );
130
131	if ( Webfinger::is_acct( $decoded_url ) ) {
132	return true;
133	}
134
135	// Must be HTTPS.
136	if ( 'https' !== \wp_parse_url( $decoded_url, PHP_URL_SCHEME ) ) {
137	return false;
138	}
139
140	// Use WordPress built-in validation (blocks local IPs, restricts ports).
141	return (bool) \wp_http_validate_url( $decoded_url );
142	}
143
144	/**
145	* Fetch a remote ActivityPub object via the proxy.
146	*
147	* @see https://www.w3.org/wiki/ActivityPub/Primer/proxyUrl_endpoint
148	*
149	* @param \WP_REST_Request $request Full details about the request.
150	* @return \WP_REST_Response\|\WP_Error Response object on success, WP_Error on failure.
151	*/
152	public function create_item( $request ) {
153	// Rate-limit proxy requests (max 30 per minute per user).
154	$user_id = \get_current_user_id();
155	$transient_key = 'ap_proxy_' . $user_id;
156	$count = (int) \get_transient( $transient_key );
157
158	if ( $count >= 30 ) {
159	return new \WP_Error(
160	'activitypub_rate_limit',
161	\__( 'Too many proxy requests. Please try again later.', 'activitypub' ),
162	array( 'status' => 429 )
163	);
164	}
165
166	\set_transient( $transient_key, $count + 1, MINUTE_IN_SECONDS );
167
168	$url = $request->get_param( 'id' );
169
170	// Try to fetch as an actor first using Remote_Actors which handles caching.
171	$post = Remote_Actors::fetch_by_various( $url );
172
173	if ( ! \is_wp_error( $post ) ) {
174	$actor = Remote_Actors::get_actor( $post );
175
176	if ( ! \is_wp_error( $actor ) ) {
177	$response = new \WP_REST_Response( $actor->to_array(), 200 );
178	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
179
180	return $response;
181	}
182	}
183
184	// Fall back to fetching as a generic object.
185	$object = Http::get_remote_object( $url );
186
187	if ( \is_wp_error( $object ) ) {
188	return new \WP_Error(
189	'activitypub_fetch_failed',
190	\__( 'Failed to fetch the remote object.', 'activitypub' ),
191	array( 'status' => 502 )
192	);
193	}
194
195	// If it's an actor, store it for future use.
196	if ( is_actor( $object ) ) {
197	Remote_Actors::upsert( $object );
198	}
199
200	$response = new \WP_REST_Response( $object, 200 );
201	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
202
203	return $response;
204	}
205
206	/**
207	* Get the schema for the proxy endpoint.
208	*
209	* @return array Schema array.
210	*/
211	public function get_item_schema() {
212	return array(
213	'$schema' => 'http://json-schema.org/draft-04/schema#',
214	'title' => 'proxy',
215	'type' => 'object',
216	'properties' => array(
217	'id' => array(
218	'description' => \__( 'The URI of the remote ActivityPub object.', 'activitypub' ),
219	'type' => 'string',
220	'format' => 'uri',
221	'context' => array( 'view' ),
222	),
223	),
224	);
225	}
226
227	/**
228	* Proxy a remote eventStream.
229	*
230	* Fetches the remote object to discover its eventStream URL,
231	* then opens a streaming connection and relays SSE events.
232	*
233	* @param \WP_REST_Request $request Full details about the request.
234	*
235	* @return \WP_Error\|void WP_Error on failure, exits on success.
236	*/
237	public function get_stream( $request ) {
238	$remote_id = $request->get_param( 'id' );
239
240	$object = Http::get_remote_object( $remote_id );
241
242	if ( \is_wp_error( $object ) ) {
243	return new \WP_Error(
244	'activitypub_proxy_fetch_failed',
245	\__( 'Failed to fetch the remote object.', 'activitypub' ),
246	array( 'status' => 502 )
247	);
248	}
249
250	$stream_url = isset( $object['eventStream'] ) ? $object['eventStream'] : null;
251
252	if ( ! $stream_url ) {
253	return new \WP_Error(
254	'activitypub_no_event_stream',
255	\__( 'The remote object does not advertise an eventStream.', 'activitypub' ),
256	array( 'status' => 404 )
257	);
258	}
259
260	if ( ! $this->validate_url( $stream_url ) ) {
261	return new \WP_Error(
262	'activitypub_invalid_event_stream',
263	\__( 'The remote eventStream URL is not valid.', 'activitypub' ),
264	array( 'status' => 400 )
265	);
266	}
267
268	$this->relay_remote_stream( $stream_url );
269	}
270	}
271