embed-privacy / inc / integration / class-activitypub.php

class-activitypub.php in Embed Privacy trunk, at inc/integration/class-activitypub.php

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1	<?php
2	namespace epiphyt\Embed_Privacy\integration;
3
4	use Activitypub\Signature;
5	use DateTimeImmutable;
6	use epiphyt\Embed_Privacy\data\Embed_Cache;
7
8	/**
9	* ActivityPub integration for Embed Privacy.
10	*
11	* @author Epiphyt
12	* @license GPL2
13	* @package epiphyt\Embed_Privacy
14	* @since 1.10.0
15	*/
16	final class Activitypub {
17	/**
18	* @var string Local toot template
19	*/
20	private static $toot_template = '<blockquote class="embed-privacy__toot">
21	%1$s
22	<cite class="embed-privacy__toot--meta">
23	<span class="embed-privacy__toot--author-meta"><a href="%3$s">%2$s</a></span>
24	<span class="embed-privacy__toot--date-meta"><a href="%5$s">%4$s</a></span>
25	</cite>
26	</blockquote>';
27
28	/**
29	* Initialize functionality.
30	*/
31	public static function init() {
32	\add_filter( 'pre_oembed_result', [ self::class, 'maybe_set_cache' ], 9, 2 );
33	\add_filter( 'embed_privacy_custom_oembed_replacement', [ self::class, 'maybe_set_local_toot' ], 10, 4 );
34	\add_filter( 'embed_privacy_is_ignored_request', [ self::class, 'set_ignored_request' ] );
35	}
36
37	/**
38	* Get remote embed data.
39	*
40	* @param string $url URL to retrieve embed data from
41	* @return ?\stdClass JSON object or null
42	*/
43	private static function get_remote_embed_data( $url ) {
44	$date = \gmdate( 'D, d M Y H:i:s T' );
45	$headers = [
46	'Accept' => 'application/activity+json',
47	'Content-Type' => 'application/activity+json',
48	'Date' => $date,
49	];
50
51	if ( \method_exists( '\Activitypub\Signature', 'generate_signature' ) ) {
52	$headers['Signature'] = Signature::generate_signature( -1, 'get', $url, $date );
53	}
54
55	$request = \wp_safe_remote_get(
56	$url,
57	[
58	'headers' => $headers,
59	]
60	);
61
62	if ( \is_wp_error( $request ) ) {
63	return null;
64	}
65
66	$response = \wp_remote_retrieve_body( $request );
67	$json = \json_decode( $response );
68
69	if ( ! $json ) {
70	return null;
71	}
72
73	return $json;
74	}
75
76	/**
77	* Get a local toot.
78	*
79	* @param \stdClass $data ActivityPub response object
80	* @return string Local toot markup
81	*/
82	private static function get_local_toot( $data ) {
83	$date = new DateTimeImmutable( $data->published );
84	$date = $date->setTimezone( \wp_timezone() );
85
86	// phpcs:disable WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
87	return \sprintf(
88	self::$toot_template,
89	\wp_kses_post( $data->content ),
90	\esc_html( self::get_username_from_attributed_to( $data->attributedTo ) ),
91	\esc_url( $data->attributedTo ),
92	$date->format( \get_option( 'date_format' ) . ' ' . \get_option( 'time_format' ) ),
93	\esc_url( $data->url )
94	);
95	// phpcs:enable WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
96	}
97
98	/**
99	* Extract the username from the 'attributedTo' field.
100	*
101	* @param string $attributed_to Content of the 'attributedTo' field
102	* @return string Username in Webfinger format
103	*/
104	private static function get_username_from_attributed_to( $attributed_to ) {
105	$parts = \wp_parse_url( $attributed_to );
106	$username = '';
107
108	if ( isset( $parts['path'] ) ) {
109	if ( \strpos( $parts['path'], '/users/' ) === 0 ) {
110	$username = '@' . \str_replace( '/users/', '', $parts['path'] );
111	}
112	else if ( \strpos( $parts['path'], '/author/' ) === 0 ) {
113	$username = '@' . \str_replace( '/author/', '', $parts['path'] );
114	}
115
116	$username = \rtrim( $username, '/' );
117	}
118
119	if ( isset( $parts['host'] ) ) {
120	$username .= '@' . $parts['host'];
121	}
122
123	return $username;
124	}
125
126	/**
127	* Check, whether the current content is a valid ActivityPub embed.
128	*
129	* @param mixed $content Given content
130	* @return bool Whether the current content is a valid ActivityPub embed
131	*/
132	public static function is_valid_embed( $content ) {
133	if ( ! \is_object( $content ) ) {
134	return false;
135	}
136
137	$supported_types = [
138	'Article',
139	'Document',
140	'Event',
141	'Note',
142	'Page',
143	'Tombstone',
144	];
145
146	$has_context = isset( $content->{'@context'} ) && $content->{'@context'}[0] === 'https://www.w3.org/ns/activitystreams';
147	$is_type = \in_array( $content->type, $supported_types, true );
148
149	return $has_context && $is_type;
150	}
151
152	/**
153	* Maybe set a cache for an ActivityPub embed.
154	* Creates a cache entry only if there is no oEmbed result yet.
155	*
156	* @param ?string $result Current oEmbed result
157	* @param string $url Current oEmbed URL
158	* @return string\|false\|null oEmbed result
159	*/
160	public static function maybe_set_cache( $result, $url ) {
161	if ( ! \get_option( 'embed_privacy_local_activitypub_posts' ) ) {
162	return $result;
163	}
164
165	if ( $result !== null ) {
166	return $result;
167	}
168
169	$cache = Embed_Cache::get( $url );
170
171	if ( $cache === false ) {
172	$cache = self::get_remote_embed_data( $url );
173
174	Embed_Cache::set( $url, $cache );
175	}
176
177	return $result;
178	}
179
180	/**
181	* Set a local toot if it's a valid ActivityPub embed.
182	*
183	* @param string $custom_replacement Current custom replacement
184	* @param string $content The original content
185	* @param \epiphyt\Embed_privacy\embed\Provider $provider Current provider
186	* @param string $url Embed URL
187	* @return string Local toot or original embed
188	*/
189	public static function maybe_set_local_toot( $custom_replacement, $content, $provider, $url ) {
190	if ( ! \get_option( 'embed_privacy_local_activitypub_posts' ) ) {
191	return $custom_replacement;
192	}
193
194	$cache = Embed_Cache::get( $url );
195
196	if ( ! self::is_valid_embed( $cache ) ) {
197	return $custom_replacement;
198	}
199
200	return self::get_local_toot( $cache );
201	}
202
203	/**
204	* Set whether the current request is an ActivityPub request and thus should be ignored.
205	* Return the unaltered value if it's already ignored.
206	*
207	* @param bool $is_ignored Whether the current request is ignored
208	* @return bool Whether the current request is ignored
209	*/
210	public static function set_ignored_request( $is_ignored ) {
211	if ( $is_ignored ) {
212	return $is_ignored;
213	}
214
215	return \function_exists( 'Activitypub\is_activitypub_request' ) && \Activitypub\is_activitypub_request();
216	}
217	}
218