activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 5.7.0, at includes/class-webfinger.php

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1	<?php
2	/**
3	* WebFinger class file.
4	*
5	* @package Activitypub
6	*/
7
8	namespace Activitypub;
9
10	use WP_Error;
11	use Activitypub\Collection\Actors;
12
13	/**
14	* ActivityPub WebFinger Class.
15	*
16	* @author Matthias Pfefferle
17	*
18	* @see https://webfinger.net/
19	*/
20	class Webfinger {
21	/**
22	* Returns a users WebFinger "resource".
23	*
24	* @param int $user_id The WordPress user id.
25	*
26	* @return string The user-resource.
27	*/
28	public static function get_user_resource( $user_id ) {
29	$user = Actors::get_by_id( $user_id );
30	if ( ! $user \|\| is_wp_error( $user ) ) {
31	return '';
32	}
33
34	return $user->get_webfinger();
35	}
36
37	/**
38	* Resolve a WebFinger resource.
39	*
40	* @param string $uri The WebFinger Resource.
41	*
42	* @return string\|WP_Error The URL or WP_Error.
43	*/
44	public static function resolve( $uri ) {
45	$data = self::get_data( $uri );
46
47	if ( \is_wp_error( $data ) ) {
48	return $data;
49	}
50
51	if ( ! is_array( $data ) \|\| empty( $data['links'] ) ) {
52	return new WP_Error(
53	'webfinger_missing_links',
54	__( 'No valid Link elements found.', 'activitypub' ),
55	array(
56	'status' => 400,
57	'data' => $data,
58	)
59	);
60	}
61
62	foreach ( $data['links'] as $link ) {
63	if (
64	'self' === $link['rel'] &&
65	isset( $link['type'] ) &&
66	(
67	'application/activity+json' === $link['type'] \|\|
68	'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' === $link['type']
69	)
70	) {
71	return $link['href'];
72	}
73	}
74
75	return new WP_Error(
76	'webfinger_url_no_activitypub',
77	__( 'The Site supports WebFinger but not ActivityPub', 'activitypub' ),
78	array(
79	'status' => 400,
80	'data' => $data,
81	)
82	);
83	}
84
85	/**
86	* Transform a URI to an acct <identifier>@<host>.
87	*
88	* @see https://swicg.github.io/activitypub-webfinger/#reverse-discovery
89	*
90	* @param string $uri The URI (acct:, mailto:, http:, https:).
91	*
92	* @return string\|WP_Error Error or acct URI.
93	*/
94	public static function uri_to_acct( $uri ) {
95	$data = self::get_data( $uri );
96
97	if ( is_wp_error( $data ) ) {
98	return $data;
99	}
100
101	// Check if subject is an acct URI.
102	if (
103	isset( $data['subject'] ) &&
104	\str_starts_with( $data['subject'], 'acct:' )
105	) {
106	return $data['subject'];
107	}
108
109	// Search for an acct URI in the aliases.
110	if ( isset( $data['aliases'] ) ) {
111	foreach ( $data['aliases'] as $alias ) {
112	if ( \str_starts_with( $alias, 'acct:' ) ) {
113	return $alias;
114	}
115	}
116	}
117
118	return new WP_Error(
119	'webfinger_url_no_acct',
120	__( 'No acct URI found.', 'activitypub' ),
121	array(
122	'status' => 400,
123	'data' => $data,
124	)
125	);
126	}
127
128	/**
129	* Convert a URI string to an identifier and its host.
130	* Automatically adds acct: if it's missing.
131	*
132	* @param string $url The URI (acct:, mailto:, http:, https:).
133	*
134	* @return WP_Error\|array Error reaction or array with identifier and host as values.
135	*/
136	public static function get_identifier_and_host( $url ) {
137	if ( ! $url ) {
138	return new WP_Error(
139	'webfinger_invalid_identifier',
140	__( 'Invalid Identifier', 'activitypub' ),
141	array(
142	'status' => 400,
143	'data' => $url,
144	)
145	);
146	}
147
148	// Remove leading @.
149	$url = ltrim( $url, '@' );
150
151	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
152	$identifier = 'acct:' . $url;
153	$scheme = 'acct';
154	} else {
155	$identifier = $url;
156	$scheme = $match[1];
157	}
158
159	$host = null;
160
161	switch ( $scheme ) {
162	case 'acct':
163	case 'mailto':
164	case 'xmpp':
165	if ( strpos( $identifier, '@' ) !== false ) {
166	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
167	}
168	break;
169	default:
170	$host = wp_parse_url( $identifier, PHP_URL_HOST );
171	break;
172	}
173
174	if ( empty( $host ) ) {
175	return new WP_Error(
176	'webfinger_invalid_identifier',
177	__( 'Invalid Identifier', 'activitypub' ),
178	array(
179	'status' => 400,
180	'data' => $url,
181	)
182	);
183	}
184
185	return array( $identifier, $host );
186	}
187
188	/**
189	* Get the WebFinger data for a given URI.
190	*
191	* @param string $uri The Identifier: <identifier>@<host> or URI.
192	*
193	* @return WP_Error\|array Error reaction or array with identifier and host as values.
194	*/
195	public static function get_data( $uri ) {
196	$identifier_and_host = self::get_identifier_and_host( $uri );
197
198	if ( is_wp_error( $identifier_and_host ) ) {
199	return $identifier_and_host;
200	}
201
202	$transient_key = self::generate_cache_key( $uri );
203
204	list( $identifier, $host ) = $identifier_and_host;
205
206	$data = \get_transient( $transient_key );
207	if ( $data ) {
208	return $data;
209	}
210
211	$webfinger_url = sprintf(
212	'https://%s/.well-known/webfinger?resource=%s',
213	$host,
214	rawurlencode( $identifier )
215	);
216
217	$response = wp_safe_remote_get(
218	$webfinger_url,
219	array(
220	'headers' => array( 'Accept' => 'application/jrd+json' ),
221	)
222	);
223
224	if ( is_wp_error( $response ) ) {
225	return new WP_Error(
226	'webfinger_url_not_accessible',
227	__( 'The WebFinger Resource is not accessible.', 'activitypub' ),
228	array(
229	'status' => 400,
230	'data' => $webfinger_url,
231	)
232	);
233	}
234
235	$body = wp_remote_retrieve_body( $response );
236	$data = json_decode( $body, true );
237
238	\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
239
240	return $data;
241	}
242
243	/**
244	* Get the Remote-Follow endpoint for a given URI.
245	*
246	* @param string $uri The WebFinger Resource URI.
247	*
248	* @return string\|WP_Error Error or the Remote-Follow endpoint URI.
249	*/
250	public static function get_remote_follow_endpoint( $uri ) {
251	$data = self::get_data( $uri );
252
253	if ( is_wp_error( $data ) ) {
254	return $data;
255	}
256
257	if ( empty( $data['links'] ) ) {
258	return new WP_Error(
259	'webfinger_missing_links',
260	__( 'No valid Link elements found.', 'activitypub' ),
261	array(
262	'status' => 400,
263	'data' => $data,
264	)
265	);
266	}
267
268	foreach ( $data['links'] as $link ) {
269	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
270	return $link['template'];
271	}
272	}
273
274	return new WP_Error(
275	'webfinger_missing_remote_follow_endpoint',
276	__( 'No valid Remote-Follow endpoint found.', 'activitypub' ),
277	array(
278	'status' => 400,
279	'data' => $data,
280	)
281	);
282	}
283
284	/**
285	* Generate a cache key for a given URI.
286	*
287	* @param string $uri A WebFinger Resource URI.
288	*
289	* @return string The cache key.
290	*/
291	public static function generate_cache_key( $uri ) {
292	$uri = ltrim( $uri, '@' );
293
294	if ( filter_var( $uri, FILTER_VALIDATE_EMAIL ) ) {
295	$uri = 'acct:' . $uri;
296	}
297
298	return 'webfinger_' . md5( $uri );
299	}
300	}
301