activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 2.5.0, 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	$data
50	);
51	}
52
53	foreach ( $data['links'] as $link ) {
54	if (
55	'self' === $link['rel'] &&
56	(
57	'application/activity+json' === $link['type'] \|\|
58	'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' === $link['type']
59	)
60	) {
61	return $link['href'];
62	}
63	}
64
65	return new WP_Error(
66	'webfinger_url_no_activitypub',
67	__( 'The Site supports WebFinger but not ActivityPub', 'activitypub' ),
68	$data
69	);
70	}
71
72	/**
73	* Transform a URI to an acct <identifier>@<host>
74	*
75	* @param string $uri The URI (acct:, mailto:, http:, https:)
76	*
77	* @return string\|WP_Error Error or acct URI
78	*/
79	public static function uri_to_acct( $uri ) {
80	$data = self::get_data( $uri );
81
82	if ( is_wp_error( $data ) ) {
83	return $data;
84	}
85
86	// check if subject is an acct URI
87	if (
88	isset( $data['subject'] ) &&
89	\str_starts_with( $data['subject'], 'acct:' )
90	) {
91	return $data['subject'];
92	}
93
94	// search for an acct URI in the aliases
95	if ( isset( $data['aliases'] ) ) {
96	foreach ( $data['aliases'] as $alias ) {
97	if ( \str_starts_with( $alias, 'acct:' ) ) {
98	return $alias;
99	}
100	}
101	}
102
103	return new WP_Error(
104	'webfinger_url_no_acct',
105	__( 'No acct URI found.', 'activitypub' ),
106	$data
107	);
108	}
109
110	/**
111	* Convert a URI string to an identifier and its host.
112	* Automatically adds acct: if it's missing.
113	*
114	* @param string $url The URI (acct:, mailto:, http:, https:)
115	*
116	* @return WP_Error\|array Error reaction or array with
117	* identifier and host as values
118	*/
119	public static function get_identifier_and_host( $url ) {
120	// remove leading @
121	$url = ltrim( $url, '@' );
122
123	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
124	$identifier = 'acct:' . $url;
125	$scheme = 'acct';
126	} else {
127	$identifier = $url;
128	$scheme = $match[1];
129	}
130
131	$host = null;
132
133	switch ( $scheme ) {
134	case 'acct':
135	case 'mailto':
136	case 'xmpp':
137	if ( strpos( $identifier, '@' ) !== false ) {
138	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
139	}
140	break;
141	default:
142	$host = wp_parse_url( $identifier, PHP_URL_HOST );
143	break;
144	}
145
146	if ( empty( $host ) ) {
147	return new WP_Error( 'webfinger_invalid_identifier', __( 'Invalid Identifier', 'activitypub' ) );
148	}
149
150	return array( $identifier, $host );
151	}
152
153	/**
154	* Get the WebFinger data for a given URI
155	*
156	* @param string $uri The Identifier: <identifier>@<host> or URI
157	*
158	* @return WP_Error\|array Error reaction or array with
159	* identifier and host as values
160	*/
161	public static function get_data( $uri ) {
162	$identifier_and_host = self::get_identifier_and_host( $uri );
163
164	if ( is_wp_error( $identifier_and_host ) ) {
165	return $identifier_and_host;
166	}
167
168	$transient_key = self::generate_cache_key( $uri );
169
170	list( $identifier, $host ) = $identifier_and_host;
171
172	$data = \get_transient( $transient_key );
173	if ( $data ) {
174	return $data;
175	}
176
177	$webfinger_url = 'https://' . $host . '/.well-known/webfinger?resource=' . rawurlencode( $identifier );
178
179	$response = wp_safe_remote_get(
180	$webfinger_url,
181	array(
182	'headers' => array( 'Accept' => 'application/jrd+json' ),
183	)
184	);
185
186	if ( is_wp_error( $response ) ) {
187	return new WP_Error(
188	'webfinger_url_not_accessible',
189	__( 'The WebFinger Resource is not accessible.', 'activitypub' ),
190	$webfinger_url
191	);
192	}
193
194	$body = wp_remote_retrieve_body( $response );
195	$data = json_decode( $body, true );
196
197	\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
198
199	return $data;
200	}
201
202	/**
203	* Get the Remote-Follow endpoint for a given URI
204	*
205	* @return string\|WP_Error Error or the Remote-Follow endpoint URI.
206	*/
207	public static function get_remote_follow_endpoint( $uri ) {
208	$data = self::get_data( $uri );
209
210	if ( is_wp_error( $data ) ) {
211	return $data;
212	}
213
214	if ( empty( $data['links'] ) ) {
215	return new WP_Error(
216	'webfinger_missing_links',
217	__( 'No valid Link elements found.', 'activitypub' ),
218	$data
219	);
220	}
221
222	foreach ( $data['links'] as $link ) {
223	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
224	return $link['template'];
225	}
226	}
227
228	return new WP_Error(
229	'webfinger_missing_remote_follow_endpoint',
230	__( 'No valid Remote-Follow endpoint found.', 'activitypub' ),
231	$data
232	);
233	}
234
235	/**
236	* Generate a cache key for a given URI
237	*
238	* @param string $uri A WebFinger Resource URI
239	*
240	* @return string The cache key
241	*/
242	public static function generate_cache_key( $uri ) {
243	$uri = ltrim( $uri, '@' );
244
245	if ( filter_var( $uri, FILTER_VALIDATE_EMAIL ) ) {
246	$uri = 'acct:' . $uri;
247	}
248
249	return 'webfinger_' . md5( $uri );
250	}
251	}
252