activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 3.2.3, at includes/class-webfinger.php

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