activitypub / includes / class-webfinger.php

class-webfinger.php in ActivityPub 1.0.6, 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
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_resource();
34	}
35
36	/**
37	* Resolve a WebFinger resource
38	*
39	* @param string $resource The WebFinger resource
40	*
41	* @return string\|WP_Error The URL or WP_Error
42	*/
43	public static function resolve( $resource ) {
44	if ( ! preg_match( '/^@?' . ACTIVITYPUB_USERNAME_REGEXP . '$/i', $resource, $m ) ) {
45	return null;
46	}
47	$transient_key = 'activitypub_resolve_' . ltrim( $resource, '@' );
48
49	$link = \get_transient( $transient_key );
50	if ( $link ) {
51	return $link;
52	}
53
54	$url = \add_query_arg( 'resource', 'acct:' . ltrim( $resource, '@' ), 'https://' . $m[2] . '/.well-known/webfinger' );
55	if ( ! \wp_http_validate_url( $url ) ) {
56	$response = new WP_Error( 'invalid_webfinger_url', null, $url );
57	\set_transient( $transient_key, $response, HOUR_IN_SECONDS ); // Cache the error for a shorter period.
58	return $response;
59	}
60
61	// try to access author URL
62	$response = \wp_remote_get(
63	$url,
64	array(
65	'headers' => array( 'Accept' => 'application/jrd+json' ),
66	'redirection' => 2,
67	'timeout' => 2,
68	)
69	);
70
71	if ( \is_wp_error( $response ) ) {
72	$link = new WP_Error( 'webfinger_url_not_accessible', null, $url );
73	\set_transient( $transient_key, $link, HOUR_IN_SECONDS ); // Cache the error for a shorter period.
74	return $link;
75	}
76
77	$body = \wp_remote_retrieve_body( $response );
78	$body = \json_decode( $body, true );
79
80	if ( empty( $body['links'] ) ) {
81	$link = new WP_Error( 'webfinger_url_invalid_response', null, $url );
82	\set_transient( $transient_key, $link, HOUR_IN_SECONDS ); // Cache the error for a shorter period.
83	return $link;
84	}
85
86	foreach ( $body['links'] as $link ) {
87	if ( 'self' === $link['rel'] && 'application/activity+json' === $link['type'] ) {
88	\set_transient( $transient_key, $link['href'], WEEK_IN_SECONDS );
89	return $link['href'];
90	}
91	}
92
93	$link = new WP_Error( 'webfinger_url_no_activitypub', null, $body );
94	\set_transient( $transient_key, $link, HOUR_IN_SECONDS ); // Cache the error for a shorter period.
95	return $link;
96	}
97
98	/**
99	* Convert a URI string to an identifier and its host.
100	* Automatically adds acct: if it's missing.
101	*
102	* @param string $url The URI (acct:, mailto:, http:, https:)
103	*
104	* @return WP_Error\|array Error reaction or array with
105	* identifier and host as values
106	*/
107	public static function get_identifier_and_host( $url ) {
108	// remove leading @
109	$url = ltrim( $url, '@' );
110
111	if ( ! preg_match( '/^([a-zA-Z+]+):/', $url, $match ) ) {
112	$identifier = 'acct:' . $url;
113	$scheme = 'acct';
114	} else {
115	$identifier = $url;
116	$scheme = $match[1];
117	}
118
119	$host = null;
120
121	switch ( $scheme ) {
122	case 'acct':
123	case 'mailto':
124	case 'xmpp':
125	if ( strpos( $identifier, '@' ) !== false ) {
126	$host = substr( $identifier, strpos( $identifier, '@' ) + 1 );
127	}
128	break;
129	default:
130	$host = wp_parse_url( $identifier, PHP_URL_HOST );
131	break;
132	}
133
134	if ( empty( $host ) ) {
135	return new WP_Error( 'invalid_identifier', __( 'Invalid Identifier', 'activitypub' ) );
136	}
137
138	return array( $identifier, $host );
139	}
140
141	/**
142	* Get the WebFinger data for a given URI
143	*
144	* @param string $identifier The Identifier: <identifier>@<host>
145	* @param string $host The Host: <identifier>@<host>
146	*
147	* @return WP_Error\|array Error reaction or array with
148	* identifier and host as values
149	*/
150	public static function get_data( $identifier, $host ) {
151	$webfinger_url = 'https://' . $host . '/.well-known/webfinger?resource=' . rawurlencode( $identifier );
152
153	$response = wp_safe_remote_get(
154	$webfinger_url,
155	array(
156	'headers' => array( 'Accept' => 'application/jrd+json' ),
157	'redirection' => 0,
158	'timeout' => 2,
159	)
160	);
161
162	if ( is_wp_error( $response ) ) {
163	return new WP_Error( 'webfinger_url_not_accessible', null, $webfinger_url );
164	}
165
166	$body = wp_remote_retrieve_body( $response );
167
168	return json_decode( $body, true );
169	}
170
171	/**
172	* Undocumented function
173	*
174	* @return void
175	*/
176	public static function get_remote_follow_endpoint( $uri ) {
177	$identifier_and_host = self::get_identifier_and_host( $uri );
178
179	if ( is_wp_error( $identifier_and_host ) ) {
180	return $identifier_and_host;
181	}
182
183	list( $identifier, $host ) = $identifier_and_host;
184
185	$data = self::get_data( $identifier, $host );
186
187	if ( is_wp_error( $data ) ) {
188	return $data;
189	}
190
191	if ( empty( $data['links'] ) ) {
192	return new WP_Error( 'webfinger_url_invalid_response', null, $data );
193	}
194
195	foreach ( $data['links'] as $link ) {
196	if ( 'http://ostatus.org/schema/1.0/subscribe' === $link['rel'] ) {
197	return $link['template'];
198	}
199	}
200
201	return new WP_Error( 'webfinger_remote_follow_endpoint_invalid', $data, array( 'status' => 417 ) );
202	}
203	}
204