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

class-proxy-controller.php in ActivityPub 9.1.0, at includes/rest/class-proxy-controller.php

267 lines 7.6 KB

Raw Download Zip

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	/**
18	* Proxy Controller.
19	*
20	* Provides a bridge between C2S OAuth authentication and S2S HTTP Signature authentication.
21	* Allows C2S clients to fetch remote ActivityPub objects through their home server.
22	*/
23	class Proxy_Controller extends \WP_REST_Controller {
24	use Event_Stream;
25	use Verification;
26
27	/**
28	* The namespace of this controller's route.
29	*
30	* @var string
31	*/
32	protected $namespace = ACTIVITYPUB_REST_NAMESPACE;
33
34	/**
35	* The base of this controller's route.
36	*
37	* @var string
38	*/
39	protected $rest_base = 'proxy';
40
41	/**
42	* Register routes.
43	*/
44	public function register_routes() {
45	\register_rest_route(
46	$this->namespace,
47	'/' . $this->rest_base,
48	array(
49	array(
50	'methods' => \WP_REST_Server::CREATABLE,
51	'callback' => array( $this, 'create_item' ),
52	'permission_callback' => array( $this, 'verify_authentication' ),
53	'args' => array(
54	'id' => array(
55	'description' => 'The remote ActivityPub object to fetch: an HTTPS URL or an acct identifier (`user@host`, `@user@host`, or `acct:user@host`).',
56	'type' => 'string',
57	'required' => true,
58	'sanitize_callback' => array( $this, 'sanitize_url' ),
59	'validate_callback' => array( $this, 'validate_url' ),
60	),
61	),
62	),
63	'schema' => array( $this, 'get_item_schema' ),
64	)
65	);
66
67	\register_rest_route(
68	$this->namespace,
69	'/' . $this->rest_base . '/stream',
70	array(
71	array(
72	'methods' => \WP_REST_Server::READABLE,
73	'callback' => array( $this, 'get_stream' ),
74	'permission_callback' => array( $this, 'get_stream_permissions_check' ),
75	'args' => array(
76	'id' => array(
77	'description' => 'The remote actor identifier (URL or WebFinger acct) whose eventStream to proxy.',
78	'type' => 'string',
79	'required' => true,
80	'sanitize_callback' => array( $this, 'sanitize_url' ),
81	'validate_callback' => array( $this, 'validate_url' ),
82	),
83	),
84	),
85	)
86	);
87	}
88
89	/**
90	* Sanitize the `id` parameter.
91	*
92	* Accepts either an HTTPS URL or an acct identifier (`user@host`,
93	* `@user@host`, or `acct:user@host`). Acct identifiers are returned
94	* as-is; URLs are run through `sanitize_url()`. Matches the dual-shape
95	* contract of `Remote_Actors::fetch_by_various()`.
96	*
97	* @see https://developer.wordpress.org/reference/functions/sanitize_url/
98	*
99	* @param string $url The urlencoded URL or acct identifier to sanitize.
100	* @return string The sanitized value.
101	*/
102	public function sanitize_url( $url ) {
103	$decoded = \urldecode( $url );
104
105	if ( Webfinger::is_acct( $decoded ) ) {
106	return $decoded;
107	}
108
109	return \sanitize_url( $decoded );
110	}
111
112	/**
113	* Validate the `id` parameter.
114	*
115	* Accepts either an HTTPS URL (validated via `wp_http_validate_url()`,
116	* which blocks local/private IPs and restricts ports) or an acct
117	* identifier in any of the forms accepted by `Webfinger::is_acct()`:
118	* `user@host`, `@user@host`, or `acct:user@host`. Matches the
119	* dual-shape contract of `Remote_Actors::fetch_by_various()`.
120	*
121	* @see https://developer.wordpress.org/reference/functions/wp_http_validate_url/
122	*
123	* @param string $url The URL or acct identifier to validate.
124	* @return bool True if valid, false otherwise.
125	*/
126	public function validate_url( $url ) {
127	$decoded_url = \urldecode( $url );
128
129	if ( Webfinger::is_acct( $decoded_url ) ) {
130	return true;
131	}
132
133	// Must be HTTPS.
134	if ( 'https' !== \wp_parse_url( $decoded_url, PHP_URL_SCHEME ) ) {
135	return false;
136	}
137
138	// Use WordPress built-in validation (blocks local IPs, restricts ports).
139	return (bool) \wp_http_validate_url( $decoded_url );
140	}
141
142	/**
143	* Fetch a remote ActivityPub object via the proxy.
144	*
145	* @see https://www.w3.org/wiki/ActivityPub/Primer/proxyUrl_endpoint
146	*
147	* @param \WP_REST_Request $request Full details about the request.
148	* @return \WP_REST_Response\|\WP_Error Response object on success, WP_Error on failure.
149	*/
150	public function create_item( $request ) {
151	// Rate-limit proxy requests (max 30 per minute per user).
152	$user_id = \get_current_user_id();
153	$transient_key = 'ap_proxy_' . $user_id;
154	$count = (int) \get_transient( $transient_key );
155
156	if ( $count >= 30 ) {
157	return new \WP_Error(
158	'activitypub_rate_limit',
159	\__( 'Too many proxy requests. Please try again later.', 'activitypub' ),
160	array( 'status' => 429 )
161	);
162	}
163
164	\set_transient( $transient_key, $count + 1, MINUTE_IN_SECONDS );
165
166	$url = $request->get_param( 'id' );
167
168	// Try to fetch as an actor first using Remote_Actors which handles caching.
169	$post = Remote_Actors::fetch_by_various( $url );
170
171	if ( ! \is_wp_error( $post ) ) {
172	$actor = Remote_Actors::get_actor( $post );
173
174	if ( ! \is_wp_error( $actor ) ) {
175	$response = new \WP_REST_Response( $actor->to_array(), 200 );
176	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
177
178	return $response;
179	}
180	}
181
182	/*
183	* Fall back to fetching as a generic object. Actors are already resolved and
184	* cached above via fetch_by_various(), so this path only proxies the object.
185	*/
186	$object = Http::get_remote_object( $url );
187
188	if ( \is_wp_error( $object ) ) {
189	return new \WP_Error(
190	'activitypub_fetch_failed',
191	\__( 'Failed to fetch the remote object.', 'activitypub' ),
192	array( 'status' => 502 )
193	);
194	}
195
196	$response = new \WP_REST_Response( $object, 200 );
197	$response->header( 'Content-Type', 'application/activity+json; charset=' . \get_option( 'blog_charset' ) );
198
199	return $response;
200	}
201
202	/**
203	* Get the schema for the proxy endpoint.
204	*
205	* @return array Schema array.
206	*/
207	public function get_item_schema() {
208	return array(
209	'$schema' => 'http://json-schema.org/draft-04/schema#',
210	'title' => 'proxy',
211	'type' => 'object',
212	'properties' => array(
213	'id' => array(
214	'description' => \__( 'The URI of the remote ActivityPub object.', 'activitypub' ),
215	'type' => 'string',
216	'format' => 'uri',
217	'context' => array( 'view' ),
218	),
219	),
220	);
221	}
222
223	/**
224	* Proxy a remote eventStream.
225	*
226	* Fetches the remote object to discover its eventStream URL,
227	* then opens a streaming connection and relays SSE events.
228	*
229	* @param \WP_REST_Request $request Full details about the request.
230	*
231	* @return \WP_Error\|void WP_Error on failure, exits on success.
232	*/
233	public function get_stream( $request ) {
234	$remote_id = $request->get_param( 'id' );
235
236	$object = Http::get_remote_object( $remote_id );
237
238	if ( \is_wp_error( $object ) ) {
239	return new \WP_Error(
240	'activitypub_proxy_fetch_failed',
241	\__( 'Failed to fetch the remote object.', 'activitypub' ),
242	array( 'status' => 502 )
243	);
244	}
245
246	$stream_url = isset( $object['eventStream'] ) ? $object['eventStream'] : null;
247
248	if ( ! $stream_url ) {
249	return new \WP_Error(
250	'activitypub_no_event_stream',
251	\__( 'The remote object does not advertise an eventStream.', 'activitypub' ),
252	array( 'status' => 404 )
253	);
254	}
255
256	if ( ! $this->validate_url( $stream_url ) ) {
257	return new \WP_Error(
258	'activitypub_invalid_event_stream',
259	\__( 'The remote eventStream URL is not valid.', 'activitypub' ),
260	array( 'status' => 400 )
261	);
262	}
263
264	$this->relay_remote_stream( $stream_url );
265	}
266	}
267