activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 7.8.0, 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 Activitypub\Activity\Actor;
11	use Activitypub\Collection\Actors;
12	use Activitypub\Collection\Remote_Actors;
13
14	/**
15	* ActivityPub WebFinger Class.
16	*
17	* @author Matthias Pfefferle
18	*
19	* @see https://webfinger.net/
20	*/
21	class Webfinger {
22	/**
23	* Returns a users WebFinger "resource".
24	*
25	* @param int $user_id The WordPress user id.
26	*
27	* @return string The user-resource.
28	*/
29	public static function get_user_resource( $user_id ) {
30	$user = Actors::get_by_id( $user_id );
31	if ( ! $user \|\| is_wp_error( $user ) ) {
32	return '';
33	}
34
35	return $user->get_webfinger();
36	}
37
38	/**
39	* Resolve a WebFinger resource.
40	*
41	* @param string $uri The WebFinger Resource.
42	*
43	* @return string\|\WP_Error The URL or WP_Error.
44	*/
45	public static function resolve( $uri ) {
46	$data = self::get_data( $uri );
47
48	if ( \is_wp_error( $data ) ) {
49	return $data;
50	}
51
52	if ( ! is_array( $data ) \|\| empty( $data['links'] ) ) {
53	return new \WP_Error(
54	'webfinger_missing_links',
55	__( 'No valid Link elements found.', 'activitypub' ),
56	array(
57	'status' => 400,
58	'data' => $data,
59	)
60	);
61	}
62
63	foreach ( $data['links'] as $link ) {
64	if (
65	'self' === $link['rel'] &&
66	isset( $link['type'] ) &&
67	(
68	'application/activity+json' === $link['type'] \|\|
69	'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' === $link['type']
70	)
71	) {
72	return $link['href'];
73	}
74	}
75
76	return new \WP_Error(
77	'webfinger_url_no_activitypub',
78	__( 'The Site supports WebFinger but not ActivityPub', 'activitypub' ),
79	array(
80	'status' => 400,
81	'data' => $data,
82	)
83	);
84	}
85
86	/**
87	* Transform a URI to an acct <identifier>@<host>.
88	*
89	* @see https://swicg.github.io/activitypub-webfinger/#reverse-discovery
90	*
91	* @param string $uri The URI (acct:, mailto:, http:, https:).
92	*
93	* @return string\|\WP_Error Error or acct URI.
94	*/
95	public static function uri_to_acct( $uri ) {
96	$data = self::get_data( $uri );
97
98	if ( is_wp_error( $data ) ) {
99	return $data;
100	}
101
102	// Check if subject is an acct URI.
103	if (
104	isset( $data['subject'] ) &&
105	\str_starts_with( $data['subject'], 'acct:' )
106	) {
107	return $data['subject'];
108	}
109
110	// Search for an acct URI in the aliases.
111	if ( isset( $data['aliases'] ) ) {
112	foreach ( $data['aliases'] as $alias ) {
113	if ( \str_starts_with( $alias, 'acct:' ) ) {
114	return $alias;
115	}
116	}
117	}
118
119	return new \WP_Error(
120	'webfinger_url_no_acct',
121	__( 'No acct URI found.', 'activitypub' ),
122	array(
123	'status' => 400,
124	'data' => $data,
125	)
126	);
127	}
128
129	/**
130	* Convert a URI string to an identifier and its host.
131	* Automatically adds acct: if it's missing.
132	*
133	* @param string $url The URI (acct:, mailto:, http:, https:).
134	*
135	* @return \WP_Error\|array Error reaction or array with identifier and host as values.
136	*/
137	public static function get_identifier_and_host( $url ) {
138	if ( ! $url ) {
139	return new \WP_Error(
140	'webfinger_invalid_identifier',
141	__( 'Invalid Identifier', 'activitypub' ),
142	array(
143	'status' => 400,
144	'data' => $url,
145	)
146	);
147	}
148
149	// Remove leading @.
150	$url = ltrim( $url, '@' );
151
152	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
153	$identifier = 'acct:' . $url;
154	$scheme = 'acct';
155	} else {
156	$identifier = $url;
157	$scheme = $match[1];
158	}
159
160	$host = null;
161
162	switch ( $scheme ) {
163	case 'acct':
164	case 'mailto':
165	case 'xmpp':
166	if ( strpos( $identifier, '@' ) !== false ) {
167	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
168	}
169	break;
170	default:
171	$host = wp_parse_url( $identifier, PHP_URL_HOST );
172	break;
173	}
174
175	if ( empty( $host ) ) {
176	return new \WP_Error(
177	'webfinger_invalid_identifier',
178	__( 'Invalid Identifier', 'activitypub' ),
179	array(
180	'status' => 400,
181	'data' => $url,
182	)
183	);
184	}
185
186	return array( $identifier, $host );
187	}
188
189	/**
190	* Get the WebFinger data for a given URI.
191	*
192	* @param string $uri The Identifier: <identifier>@<host> or URI.
193	*
194	* @return \WP_Error\|array Error reaction or array with identifier and host as values.
195	*/
196	public static function get_data( $uri ) {
197	$identifier_and_host = self::get_identifier_and_host( $uri );
198
199	if ( is_wp_error( $identifier_and_host ) ) {
200	return $identifier_and_host;
201	}
202
203	$transient_key = self::generate_cache_key( $uri );
204
205	list( $identifier, $host ) = $identifier_and_host;
206
207	$data = \get_transient( $transient_key );
208	if ( $data ) {
209	return $data;
210	}
211
212	$webfinger_url = sprintf(
213	'https://%s/.well-known/webfinger?resource=%s',
214	$host,
215	\rawurlencode( $identifier )
216	);
217
218	$response = \wp_safe_remote_get(
219	$webfinger_url,
220	array(
221	'headers' => array( 'Accept' => 'application/jrd+json' ),
222	)
223	);
224
225	if ( \is_wp_error( $response ) \|\| \wp_remote_retrieve_response_code( $response ) >= 400 ) {
226	return new \WP_Error(
227	'webfinger_url_not_accessible',
228	__( 'The WebFinger Resource is not accessible.', 'activitypub' ),
229	array(
230	'status' => 400,
231	'data' => $webfinger_url,
232	)
233	);
234	}
235
236	$body = \wp_remote_retrieve_body( $response );
237	$data = \json_decode( $body, true );
238
239	\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
240
241	return $data;
242	}
243
244	/**
245	* Get the Remote-Follow endpoint for a given URI.
246	*
247	* @param string $uri The WebFinger Resource URI.
248	*
249	* @return string\|\WP_Error Error or the Remote-Follow endpoint URI.
250	*/
251	public static function get_remote_follow_endpoint( $uri ) {
252	$data = self::get_data( $uri );
253
254	if ( is_wp_error( $data ) ) {
255	return $data;
256	}
257
258	if ( empty( $data['links'] ) ) {
259	return new \WP_Error(
260	'webfinger_missing_links',
261	__( 'No valid Link elements found.', 'activitypub' ),
262	array(
263	'status' => 400,
264	'data' => $data,
265	)
266	);
267	}
268
269	foreach ( $data['links'] as $link ) {
270	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
271	return $link['template'];
272	}
273	}
274
275	return new \WP_Error(
276	'webfinger_missing_remote_follow_endpoint',
277	__( 'No valid Remote-Follow endpoint found.', 'activitypub' ),
278	array(
279	'status' => 400,
280	'data' => $data,
281	)
282	);
283	}
284
285	/**
286	* Generate a cache key for a given URI.
287	*
288	* @param string $uri A WebFinger Resource URI.
289	*
290	* @return string The cache key.
291	*/
292	public static function generate_cache_key( $uri ) {
293	$uri = ltrim( $uri, '@' );
294
295	if ( filter_var( $uri, FILTER_VALIDATE_EMAIL ) ) {
296	$uri = 'acct:' . $uri;
297	}
298
299	return 'webfinger_' . md5( $uri );
300	}
301
302	/**
303	* Infer a shortname from the Actor ID or URL. Used only for fallbacks,
304	* we will try to use what's supplied.
305	*
306	* @param Actor\|string $actor_or_uri The Actor or URI.
307	*
308	* @return string Hopefully the name of the Follower.
309	*/
310	public static function guess( $actor_or_uri ) {
311	if ( ! $actor_or_uri instanceof Actor ) {
312	$actor = Remote_Actors::fetch_by_uri( $actor_or_uri );
313	if ( \is_wp_error( $actor ) ) {
314	return extract_name_from_uri( $actor_or_uri ) . '@' . \wp_parse_url( $actor_or_uri, PHP_URL_HOST );
315	}
316
317	$actor_or_uri = $actor;
318	}
319
320	if ( $actor_or_uri->get_preferred_username() ) {
321	return $actor_or_uri->get_preferred_username() . '@' . \wp_parse_url( $actor_or_uri->get_id(), PHP_URL_HOST );
322	}
323
324	return extract_name_from_uri( $actor_or_uri->get_id() ) . '@' . \wp_parse_url( $actor_or_uri->get_id(), PHP_URL_HOST );
325	}
326	}
327