xspeed / includes / class-edge-mode-probe.php

class-edge-mode-probe.php in xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN 1.4.1, at includes/class-edge-mode-probe.php

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1	<?php
2	/**
3	* Whether the Cloudflare edge in front of the site obeys "do not store".
4	*
5	* xSpeed marks first renders, bypassed pages and per-visitor pages
6	* `no-store` for the edge. That only works when the edge reads the site's
7	* headers. A Cloudflare Cache Rule whose Edge TTL ignores the origin, or
8	* Cloudflare Enterprise bought from xCloud with Edge Page Caching in
9	* `override_origin` mode, stores every HTML response anyway, so a cart or
10	* account page can be served to the next visitor. Nothing on the site can
11	* read those settings, so this asks the edge directly: it requests a page
12	* that answers `no-store` twice, and a cached second answer means the edge
13	* ignores the site.
14	*
15	* The round-trips run from cron. Health only reads the stored verdict.
16	*
17	* @package XSpeed
18	*/
19
20	namespace XSpeed;
21
22	defined( 'ABSPATH' ) \|\| exit;
23
24	final class Edge_Mode_Probe {
25
26	/** Stored verdict. */
27	public const TRANSIENT = 'xspeed_edge_mode_probe';
28
29	/** Token the probe page answers to, set for the length of one probe. */
30	private const TOKEN_TRANSIENT = 'xspeed_edge_mode_probe_token';
31
32	/** Query parameter the probe page answers on. */
33	public const PARAM = 'xspeed_edge_probe';
34
35	/** Cron hook for the background run. */
36	public const CRON_HOOK = 'xspeed_edge_mode_probe_refresh';
37
38	/** The edge stored a `no-store` page: it ignores the site's headers. */
39	public const IGNORES_ORIGIN = 'ignores_origin';
40
41	/** The edge did not store it. */
42	public const RESPECTS_ORIGIN = 'respects_origin';
43
44	/** No Cloudflare in front, as far as the probe could see. */
45	public const NOT_CLOUDFLARE = 'not_cloudflare';
46
47	/** The probe could not finish. */
48	public const UNKNOWN = 'unknown';
49
50	/** Answer the probe request, before anything else renders. */
51	public static function boot(): void {
52	add_action( 'init', array( __CLASS__, 'maybe_answer' ), 0 );
53	}
54
55	/**
56	* The verdict from the two answers' Cloudflare headers.
57	*
58	* Pure, so the rule is tested without a network.
59	*
60	* @param array{ray:string,status:string} $first First answer.
61	* @param array{ray:string,status:string} $second Second answer.
62	*/
63	public static function verdict( array $first, array $second ): string {
64	if ( '' === $first['ray'] && '' === $second['ray'] ) {
65	return self::NOT_CLOUDFLARE;
66	}
67	$stored = array( 'HIT', 'STALE', 'UPDATING', 'REVALIDATED' );
68	return in_array( strtoupper( $second['status'] ), $stored, true ) ? self::IGNORES_ORIGIN : self::RESPECTS_ORIGIN;
69	}
70
71	/**
72	* The stored verdict. A cold one schedules a background run and reads
73	* as unknown, so a dashboard load never waits on the edge.
74	*
75	* @return array{verdict:string,checked_at:int}
76	*/
77	public static function cached(): array {
78	$cached = get_transient( self::TRANSIENT );
79	if ( is_array( $cached ) && isset( $cached['verdict'] ) ) {
80	return array(
81	'verdict' => (string) $cached['verdict'],
82	'checked_at' => (int) ( $cached['checked_at'] ?? 0 ),
83	);
84	}
85	self::schedule();
86	return array(
87	'verdict' => self::UNKNOWN,
88	'checked_at' => 0,
89	);
90	}
91
92	/** Queue one background run, unless one is pending. */
93	public static function schedule(): void {
94	if ( ! function_exists( 'wp_next_scheduled' ) \|\| wp_next_scheduled( self::CRON_HOOK ) ) {
95	return;
96	}
97	wp_schedule_single_event( time() + 30, self::CRON_HOOK );
98	}
99
100	/**
101	* Run the probe: two requests through whatever is in front of the site.
102	*
103	* @return array{verdict:string,checked_at:int}
104	*/
105	public static function run(): array {
106	$token = function_exists( 'wp_generate_password' ) ? wp_generate_password( 16, false ) : bin2hex( random_bytes( 8 ) );
107	set_transient( self::TOKEN_TRANSIENT, $token, 2 * MINUTE_IN_SECONDS );
108
109	$url = add_query_arg( self::PARAM, $token, home_url( '/' ) );
110	$first = self::fetch( $url );
111	$second = null === $first ? null : self::fetch( $url );
112	delete_transient( self::TOKEN_TRANSIENT );
113
114	if ( null === $first \|\| null === $second ) {
115	$result = array(
116	'verdict' => self::UNKNOWN,
117	'checked_at' => time(),
118	);
119	set_transient( self::TRANSIENT, $result, HOUR_IN_SECONDS );
120	return $result;
121	}
122
123	$result = array(
124	'verdict' => self::verdict( $first, $second ),
125	'checked_at' => time(),
126	);
127	set_transient( self::TRANSIENT, $result, 12 * HOUR_IN_SECONDS );
128	return $result;
129	}
130
131	/**
132	* One request, or null when it failed.
133	*
134	* @param string $url Probe URL.
135	* @return array{ray:string,status:string}\|null
136	*/
137	private static function fetch( string $url ): ?array {
138	$res = wp_remote_get(
139	$url,
140	array(
141	'timeout' => 10,
142	'redirection' => 0,
143	'headers' => Self_Traffic::headers( array( 'User-Agent' => 'xSpeed Health Probe/1.0' ) ),
144	'cookies' => array(),
145	'sslverify' => ! Cookie_Inspector::is_local_host( home_url( '/' ) ),
146	)
147	);
148	if ( is_wp_error( $res ) \|\| 200 !== (int) wp_remote_retrieve_response_code( $res ) ) {
149	return null;
150	}
151	return array(
152	'ray' => (string) wp_remote_retrieve_header( $res, 'cf-ray' ),
153	'status' => (string) wp_remote_retrieve_header( $res, 'cf-cache-status' ),
154	);
155	}
156
157	/**
158	* Answer the probe with a small HTML page marked `no-store` everywhere.
159	* Only while a probe is running, and only for its token.
160	*/
161	public static function maybe_answer(): void {
162	// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- an anonymous probe; the token below is the check.
163	$given = isset( $_GET[ self::PARAM ] ) ? sanitize_text_field( wp_unslash( $_GET[ self::PARAM ] ) ) : '';
164	if ( ! self::answers( $given ) ) {
165	return;
166	}
167	self::send_answer();
168	exit;
169	}
170
171	/**
172	* Whether a request carrying this token is the running probe.
173	*
174	* @param string $given Token from the query string.
175	*/
176	public static function answers( string $given ): bool {
177	if ( '' === $given ) {
178	return false;
179	}
180	$token = get_transient( self::TOKEN_TRANSIENT );
181	return is_string( $token ) && '' !== $token && hash_equals( $token, $given );
182	}
183
184	/** The probe page's headers and body. */
185	public static function send_answer(): void {
186	if ( ! headers_sent() ) {
187	status_header( 200 );
188	header( 'Content-Type: text/html; charset=utf-8' );
189	header( 'Cache-Control: no-store, private' );
190	header( 'CDN-Cache-Control: no-store' );
191	header( 'Cloudflare-CDN-Cache-Control: no-store' );
192	}
193	echo '<!doctype html><title>xSpeed edge probe</title>';
194	}
195
196	/**
197	* Health row when the edge stores pages it was told not to. Null
198	* otherwise: a site whose edge obeys has nothing to act on.
199	*
200	* @param string $verdict Stored verdict.
201	* @param bool $xcloud_cfe Cloudflare Enterprise comes from xCloud's
202	* purge plugin on this site.
203	* @return array{id:string,tone:string,label:string,detail:string}\|null
204	*/
205	public static function health_row( string $verdict, bool $xcloud_cfe ): ?array {
206	if ( self::IGNORES_ORIGIN !== $verdict ) {
207	return null;
208	}
209	$fix = $xcloud_cfe
210	? 'This domain\'s Cloudflare Enterprise comes from xCloud. Ask xCloud to set its edge caching mode to respect origin (edge_ttl_mode: respect_origin), or turn Edge Page Caching off in xCloud.'
211	: 'A Cloudflare Cache Rule probably sets Edge TTL to "Ignore cache-control header and use this TTL". Set it to "Respect origin TTL", or leave HTML out of that rule.';
212	return array(
213	'id' => 'edge_mode',
214	'tone' => Health::WARN,
215	'label' => 'Cloudflare stores pages marked do-not-store',
216	'detail' => 'A test page sent with "do not store" came back from Cloudflare\'s cache, so cart, account and other per-visitor pages can be served to the wrong visitor. ' . $fix,
217	);
218	}
219	}
220