activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 2.1.0, 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	'application/activity+json' === $link['type']
57	) {
58	return $link['href'];
59	}
60	}
61
62	return new WP_Error(
63	'webfinger_url_no_activitypub',
64	__( 'The Site supports WebFinger but not ActivityPub', 'activitypub' ),
65	$data
66	);
67	}
68
69	/**
70	* Transform a URI to an acct <identifier>@<host>
71	*
72	* @param string $uri The URI (acct:, mailto:, http:, https:)
73	*
74	* @return string\|WP_Error Error or acct URI
75	*/
76	public static function uri_to_acct( $uri ) {
77	$data = self::get_data( $uri );
78
79	if ( is_wp_error( $data ) ) {
80	return $data;
81	}
82
83	// check if subject is an acct URI
84	if (
85	isset( $data['subject'] ) &&
86	\str_starts_with( $data['subject'], 'acct:' )
87	) {
88	return $data['subject'];
89	}
90
91	// search for an acct URI in the aliases
92	if ( isset( $data['aliases'] ) ) {
93	foreach ( $data['aliases'] as $alias ) {
94	if ( \str_starts_with( $alias, 'acct:' ) ) {
95	return $alias;
96	}
97	}
98	}
99
100	return new WP_Error(
101	'webfinger_url_no_acct',
102	__( 'No acct URI found.', 'activitypub' ),
103	$data
104	);
105	}
106
107	/**
108	* Convert a URI string to an identifier and its host.
109	* Automatically adds acct: if it's missing.
110	*
111	* @param string $url The URI (acct:, mailto:, http:, https:)
112	*
113	* @return WP_Error\|array Error reaction or array with
114	* identifier and host as values
115	*/
116	public static function get_identifier_and_host( $url ) {
117	// remove leading @
118	$url = ltrim( $url, '@' );
119
120	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
121	$identifier = 'acct:' . $url;
122	$scheme = 'acct';
123	} else {
124	$identifier = $url;
125	$scheme = $match[1];
126	}
127
128	$host = null;
129
130	switch ( $scheme ) {
131	case 'acct':
132	case 'mailto':
133	case 'xmpp':
134	if ( strpos( $identifier, '@' ) !== false ) {
135	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
136	}
137	break;
138	default:
139	$host = wp_parse_url( $identifier, PHP_URL_HOST );
140	break;
141	}
142
143	if ( empty( $host ) ) {
144	return new WP_Error( 'webfinger_invalid_identifier', __( 'Invalid Identifier', 'activitypub' ) );
145	}
146
147	return array( $identifier, $host );
148	}
149
150	/**
151	* Get the WebFinger data for a given URI
152	*
153	* @param string $uri The Identifier: <identifier>@<host> or URI
154	*
155	* @return WP_Error\|array Error reaction or array with
156	* identifier and host as values
157	*/
158	public static function get_data( $uri ) {
159	$identifier_and_host = self::get_identifier_and_host( $uri );
160
161	if ( is_wp_error( $identifier_and_host ) ) {
162	return $identifier_and_host;
163	}
164
165	$transient_key = self::generate_cache_key( $uri );
166
167	list( $identifier, $host ) = $identifier_and_host;
168
169	$data = \get_transient( $transient_key );
170	if ( $data ) {
171	return $data;
172	}
173
174	$webfinger_url = 'https://' . $host . '/.well-known/webfinger?resource=' . rawurlencode( $identifier );
175
176	$response = wp_safe_remote_get(
177	$webfinger_url,
178	array(
179	'headers' => array( 'Accept' => 'application/jrd+json' ),
180	)
181	);
182
183	if ( is_wp_error( $response ) ) {
184	return new WP_Error(
185	'webfinger_url_not_accessible',
186	__( 'The WebFinger Resource is not accessible.', 'activitypub' ),
187	$webfinger_url
188	);
189	}
190
191	$body = wp_remote_retrieve_body( $response );
192	$data = json_decode( $body, true );
193
194	\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
195
196	return $data;
197	}
198
199	/**
200	* Get the Remote-Follow endpoint for a given URI
201	*
202	* @return string\|WP_Error Error or the Remote-Follow endpoint URI.
203	*/
204	public static function get_remote_follow_endpoint( $uri ) {
205	$data = self::get_data( $uri );
206
207	if ( is_wp_error( $data ) ) {
208	return $data;
209	}
210
211	if ( empty( $data['links'] ) ) {
212	return new WP_Error(
213	'webfinger_missing_links',
214	__( 'No valid Link elements found.', 'activitypub' ),
215	$data
216	);
217	}
218
219	foreach ( $data['links'] as $link ) {
220	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
221	return $link['template'];
222	}
223	}
224
225	return new WP_Error(
226	'webfinger_missing_remote_follow_endpoint',
227	__( 'No valid Remote-Follow endpoint found.', 'activitypub' ),
228	$data
229	);
230	}
231
232	/**
233	* Generate a cache key for a given URI
234	*
235	* @param string $uri A WebFinger Resource URI
236	*
237	* @return string The cache key
238	*/
239	public static function generate_cache_key( $uri ) {
240	$uri = ltrim( $uri, '@' );
241
242	if ( filter_var( $uri, FILTER_VALIDATE_EMAIL ) ) {
243	$uri = 'acct:' . $uri;
244	}
245
246	return 'webfinger_' . md5( $uri );
247	}
248	}
249