activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 2.0.0, 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	// use WebFinger plugin if installed
24	if ( \function_exists( '\get_webfinger_resource' ) ) {
25	return \get_webfinger_resource( $user_id, false );
26	}
27
28	$user = Users::get_by_id( $user_id );
29	if ( ! $user \|\| is_wp_error( $user ) ) {
30	return '';
31	}
32
33	return $user->get_webfinger();
34	}
35
36	/**
37	* Resolve a WebFinger resource
38	*
39	* @param string $uri The WebFinger Resource
40	*
41	* @return string\|WP_Error The URL or WP_Error
42	*/
43	public static function resolve( $uri ) {
44	$data = self::get_data( $uri );
45
46	if ( \is_wp_error( $data ) ) {
47	return $data;
48	}
49
50	foreach ( $data['links'] as $link ) {
51	if (
52	'self' === $link['rel'] &&
53	'application/activity+json' === $link['type']
54	) {
55	return $link['href'];
56	}
57	}
58
59	return new WP_Error( 'webfinger_url_no_activitypub', null, $data );
60	}
61
62	/**
63	* Transform a URI to an acct <identifier>@<host>
64	*
65	* @param string $uri The URI (acct:, mailto:, http:, https:)
66	*
67	* @return string\|WP_Error Error or acct URI
68	*/
69	public static function uri_to_acct( $uri ) {
70	$data = self::get_data( $uri );
71
72	if ( is_wp_error( $data ) ) {
73	return $data;
74	}
75
76	// check if subject is an acct URI
77	if (
78	isset( $data['subject'] ) &&
79	\str_starts_with( $data['subject'], 'acct:' )
80	) {
81	return $data['subject'];
82	}
83
84	// search for an acct URI in the aliases
85	if ( isset( $data['aliases'] ) ) {
86	foreach ( $data['aliases'] as $alias ) {
87	if ( \str_starts_with( $alias, 'acct:' ) ) {
88	return $alias;
89	}
90	}
91	}
92
93	return new WP_Error(
94	'webfinger_url_no_acct',
95	__( 'No acct URI found.', 'activitypub' ),
96	$data
97	);
98	}
99
100	/**
101	* Convert a URI string to an identifier and its host.
102	* Automatically adds acct: if it's missing.
103	*
104	* @param string $url The URI (acct:, mailto:, http:, https:)
105	*
106	* @return WP_Error\|array Error reaction or array with
107	* identifier and host as values
108	*/
109	public static function get_identifier_and_host( $url ) {
110	// remove leading @
111	$url = ltrim( $url, '@' );
112
113	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
114	$identifier = 'acct:' . $url;
115	$scheme = 'acct';
116	} else {
117	$identifier = $url;
118	$scheme = $match[1];
119	}
120
121	$host = null;
122
123	switch ( $scheme ) {
124	case 'acct':
125	case 'mailto':
126	case 'xmpp':
127	if ( strpos( $identifier, '@' ) !== false ) {
128	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
129	}
130	break;
131	default:
132	$host = wp_parse_url( $identifier, PHP_URL_HOST );
133	break;
134	}
135
136	if ( empty( $host ) ) {
137	return new WP_Error( 'webfinger_invalid_identifier', __( 'Invalid Identifier', 'activitypub' ) );
138	}
139
140	return array( $identifier, $host );
141	}
142
143	/**
144	* Get the WebFinger data for a given URI
145	*
146	* @param string $uri The Identifier: <identifier>@<host> or URI
147	*
148	* @return WP_Error\|array Error reaction or array with
149	* identifier and host as values
150	*/
151	public static function get_data( $uri ) {
152	$identifier_and_host = self::get_identifier_and_host( $uri );
153
154	if ( is_wp_error( $identifier_and_host ) ) {
155	return $identifier_and_host;
156	}
157
158	$transient_key = self::generate_cache_key( $uri );
159
160	list( $identifier, $host ) = $identifier_and_host;
161
162	$data = \get_transient( $transient_key );
163	if ( $data ) {
164	return $data;
165	}
166
167	$webfinger_url = 'https://' . $host . '/.well-known/webfinger?resource=' . rawurlencode( $identifier );
168
169	$response = wp_safe_remote_get(
170	$webfinger_url,
171	array(
172	'headers' => array( 'Accept' => 'application/jrd+json' ),
173	)
174	);
175
176	if ( is_wp_error( $response ) ) {
177	return new WP_Error(
178	'webfinger_url_not_accessible',
179	__( 'The WebFinger Resource is not accessible.', 'activitypub' ),
180	$webfinger_url
181	);
182	}
183
184	$body = wp_remote_retrieve_body( $response );
185	$data = json_decode( $body, true );
186
187	\set_transient( $transient_key, $data, WEEK_IN_SECONDS );
188
189	return $data;
190	}
191
192	/**
193	* Get the Remote-Follow endpoint for a given URI
194	*
195	* @return string\|WP_Error Error or the Remote-Follow endpoint URI.
196	*/
197	public static function get_remote_follow_endpoint( $uri ) {
198	$data = self::get_data( $uri );
199
200	if ( is_wp_error( $data ) ) {
201	return $data;
202	}
203
204	if ( empty( $data['links'] ) ) {
205	return new WP_Error(
206	'webfinger_missing_links',
207	__( 'No valid Link elements found.', 'activitypub' ),
208	$data
209	);
210	}
211
212	foreach ( $data['links'] as $link ) {
213	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
214	return $link['template'];
215	}
216	}
217
218	return new WP_Error(
219	'webfinger_missing_remote_follow_endpoint',
220	__( 'No valid Remote-Follow endpoint found.', 'activitypub' ),
221	$data
222	);
223	}
224
225	/**
226	* Generate a cache key for a given URI
227	*
228	* @param string $uri A WebFinger Resource URI
229	*
230	* @return string The cache key
231	*/
232	public static function generate_cache_key( $uri ) {
233	$uri = ltrim( $uri, '@' );
234
235	if ( filter_var( $uri, FILTER_VALIDATE_EMAIL ) ) {
236	$uri = 'acct:' . $uri;
237	}
238
239	return 'webfinger_' . md5( $uri );
240	}
241	}
242