activitypub / includes / rest / class-server.php

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

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1	<?php
2	/**
3	* Server REST-Class file.
4	*
5	* @package Activitypub
6	*/
7
8	namespace Activitypub\Rest;
9
10	/**
11	* ActivityPub Server REST-Class.
12	*
13	* @author Django Doucet
14	*
15	* @see https://www.w3.org/TR/activitypub/#security-verification
16	*/
17	class Server {
18	/**
19	* Initialize the class, registering WordPress hooks.
20	*/
21	public static function init() {
22	\add_filter( 'rest_request_before_callbacks', array( self::class, 'validate_requests' ), 9, 3 );
23	\add_filter( 'rest_request_parameter_order', array( self::class, 'request_parameter_order' ), 10, 2 );
24
25	\add_filter( 'rest_post_dispatch', array( self::class, 'filter_output' ), 10, 3 );
26	\add_filter( 'rest_post_dispatch', array( self::class, 'add_cors_headers' ), 10, 3 );
27	}
28
29	/**
30	* Callback function to validate incoming ActivityPub requests
31	*
32	* @param \WP_REST_Response\|\WP_HTTP_Response\|\WP_Error\|mixed $response Result to send to the client.
33	* Usually a WP_REST_Response or WP_Error.
34	* @param array $handler Route handler used for the request.
35	* @param \WP_REST_Request $request Request used to generate the response.
36	*
37	* @return mixed\|\WP_Error The response, error, or modified response.
38	*/
39	public static function validate_requests( $response, $handler, $request ) {
40	if ( 'HEAD' === $request->get_method() ) {
41	return $response;
42	}
43
44	$route = $request->get_route();
45
46	if (
47	\is_wp_error( $response ) \|\|
48	! \str_starts_with( $route, '/' . ACTIVITYPUB_REST_NAMESPACE )
49	) {
50	return $response;
51	}
52
53	$params = $request->get_json_params();
54
55	// Type is required for ActivityPub requests, so it fail later in the process.
56	if ( ! isset( $params['type'] ) ) {
57	return $response;
58	}
59
60	if (
61	ACTIVITYPUB_DISABLE_INCOMING_INTERACTIONS &&
62	in_array( $params['type'], array( 'Create', 'Like', 'Announce' ), true )
63	) {
64	return new \WP_Error(
65	'activitypub_server_does_not_accept_incoming_interactions',
66	\__( 'This server does not accept incoming interactions.', 'activitypub' ),
67	// We have to use a 2XX status code here, because otherwise the response will be
68	// treated as an error and Mastodon might block this WordPress instance.
69	array( 'status' => 202 )
70	);
71	}
72
73	return $response;
74	}
75
76	/**
77	* Modify the parameter priority order for a REST API request.
78	*
79	* @param string[] $order Array of types to check, in order of priority.
80	* @param \WP_REST_Request $request The request object.
81	*
82	* @return string[] The modified order of types to check.
83	*/
84	public static function request_parameter_order( $order, $request ) {
85	$route = $request->get_route();
86
87	// Check if it is an activitypub request and exclude webfinger and nodeinfo endpoints.
88	if ( ! \str_starts_with( $route, '/' . ACTIVITYPUB_REST_NAMESPACE ) ) {
89	return $order;
90	}
91
92	$method = $request->get_method();
93
94	if ( \WP_REST_Server::CREATABLE !== $method ) {
95	return $order;
96	}
97
98	return array(
99	'JSON',
100	'POST',
101	'URL',
102	'defaults',
103	);
104	}
105
106	/**
107	* Filters the REST API response to properly handle the ActivityPub error formatting.
108	*
109	* @see https://codeberg.org/fediverse/fep/src/branch/main/fep/c180/fep-c180.md
110	*
111	* @param \WP_HTTP_Response $response Result to send to the client. Usually a `WP_REST_Response`.
112	* @param \WP_REST_Server $server Server instance.
113	* @param \WP_REST_Request $request Request used to generate the response.
114	*
115	* @return \WP_HTTP_Response The filtered response.
116	*/
117	public static function filter_output( $response, $server, $request ) {
118	$route = $request->get_route();
119
120	// Check if it is an activitypub request and exclude webfinger and nodeinfo endpoints.
121	if ( ! \str_starts_with( $route, '/' . ACTIVITYPUB_REST_NAMESPACE ) ) {
122	return $response;
123	}
124
125	// Exclude OAuth endpoints - they have their own error format per RFC 6749.
126	if ( \str_starts_with( $route, '/' . ACTIVITYPUB_REST_NAMESPACE . '/oauth' ) ) {
127	return $response;
128	}
129
130	// Only alter responses that return an error status code.
131	if ( $response->get_status() < 400 ) {
132	return $response;
133	}
134
135	$data = $response->get_data();
136
137	// Ensure that `$data` was already converted to a response.
138	if ( \is_wp_error( $data ) ) {
139	$response = \rest_convert_error_to_response( $data );
140	$data = $response->get_data();
141	}
142
143	$error = array(
144	'type' => 'about:blank',
145	'title' => $data['code'] ?? '',
146	'detail' => $data['message'] ?? '',
147	'status' => $response->get_status(),
148
149	/*
150	* Provides the unstructured error data.
151	*
152	* @see https://nodeinfo.diaspora.software/schema.html#metadata.
153	*/
154	'metadata' => $data,
155	);
156
157	$response->set_data( $error );
158
159	return $response;
160	}
161
162	/**
163	* Add CORS headers to ActivityPub REST responses.
164	*
165	* @param \WP_REST_Response $response The REST response.
166	* @param \WP_REST_Server $server The REST server instance.
167	* @param \WP_REST_Request $request The request object.
168	*
169	* @return \WP_REST_Response The modified response.
170	*/
171	public static function add_cors_headers( $response, $server, $request ) {
172	$route = $request->get_route();
173	$namespace = '/' . ACTIVITYPUB_REST_NAMESPACE;
174
175	// Only add CORS to ActivityPub endpoints, except the interactive OAuth authorize endpoint.
176	if ( ! \str_starts_with( $route, $namespace ) \|\| \str_starts_with( $route, $namespace . '/oauth/authorize' ) ) {
177	return $response;
178	}
179
180	/*
181	* ActivityPub data is meant to be publicly readable by federation peers
182	* and browser-side clients. We do not enable credentialed cross-origin
183	* access: cookie auth would still be rejected by WordPress core's
184	* REST nonce check, and OAuth Bearer tokens travel in the
185	* Authorization header — which is permitted via Allow-Headers and
186	* does not require Allow-Credentials.
187	*/
188	$response->header( 'Access-Control-Allow-Origin', '*' );
189	$response->header( 'Access-Control-Allow-Methods', 'GET, POST, OPTIONS' );
190	$response->header( 'Access-Control-Allow-Headers', 'Accept, Content-Type, Authorization, Last-Event-ID' );
191
192	return $response;
193	}
194
195	/**
196	* Send CORS headers directly via header().
197	*
198	* Use this for endpoints that bypass the REST response flow
199	* (e.g. SSE streams that call exit() instead of returning a WP_REST_Response).
200	*
201	* @since 8.1.0
202	*/
203	public static function send_cors_headers() {
204	\header( 'Access-Control-Allow-Origin: *' );
205	\header( 'Access-Control-Allow-Methods: GET, POST, OPTIONS' );
206	\header( 'Access-Control-Allow-Headers: Accept, Content-Type, Authorization, Last-Event-ID' );
207	}
208	}
209