← All changes | includes/class-metasync-rate-limiter.php +56 -150 2.6.5 → 2.7.1 View file →

		@@ -1,13 +1,12 @@
1	1	<?php
2	2	/**
3	3	* MetaSync Rate Limiter
4	4	*
5		- * A robust rate limiting implementation that uses direct database storage
6		- * to ensure consistent behavior across all server configurations including:
7		- * - Object caching (Redis, Memcached)
8		- * - Load-balanced environments
9		- * - Server-side page caching
	5	+ * A robust rate limiting implementation that uses per-key WordPress
	6	+ * transients so each IP/token hash is stored as its own row with a
	7	+ * TTL matching the rate-limit window. This avoids the contention,
	8	+ * race conditions, and unbounded growth of a single serialized blob.
10	9	*
11	10	* @package Metasync
12	11	* @subpackage Metasync/includes
13	12	* @since 2.5.17
		@@ -20,11 +19,11 @@
20	19
21	20	class Metasync_Rate_Limiter
22	21	{
23	22	/**
24		- * Option name for storing rate limit data
	23	+ * Prefix for per-key rate limit transients.
25	24	*/
26		- const OPTION_NAME = 'metasync_rate_limits';
	25	+ const TRANSIENT_PREFIX = 'metasync_rl_';
27	26
28	27	/**
29	28	* Singleton instance
30	29	*
		@@ -49,53 +48,63 @@
49	48	* Private constructor for singleton pattern
50	49	*/
51	50	private function __construct()
52	51	{
53		- # Schedule cleanup if not already scheduled
54		- if (!wp_next_scheduled('metasync_rate_limit_cleanup')) {
55		- wp_schedule_event(time(), 'hourly', 'metasync_rate_limit_cleanup');
56		- }
	52	+ # Cancel any previously scheduled hourly cleanup job — transient
	53	+ # expiry handles cleanup automatically now.
	54	+ wp_clear_scheduled_hook('metasync_rate_limit_cleanup');
57	55	}
58	56
59	57	/**
60		- * Check and increment rate limit for a given key
	58	+ * Build the transient key for a given full rate-limit key.
61	59	*
62		- * Uses atomic database operations to ensure consistency across
63		- * all server configurations including object caching and load balancers.
	60	+ * Hashing keeps the resulting transient name comfortably under
	61	+ * WordPress's 172-char limit regardless of the input length.
64	62	*
65		- * @param string $key Unique identifier for rate limiting (e.g., hashed token or IP)
66		- * @param int $max_attempts Maximum number of attempts allowed
	63	+ * @param string $full_key Full rate-limit key (prefix + key).
	64	+ * @return string Transient name.
	65	+ */
	66	+ private function get_transient_key($full_key)
	67	+ {
	68	+ return self::TRANSIENT_PREFIX . substr(hash('sha256', $full_key), 0, 40);
	69	+ }
	70	+
	71	+ /**
	72	+ * Check and increment rate limit for a given key.
	73	+ *
	74	+ * Each key is tracked in its own transient, so concurrent
	75	+ * requests for different keys never share a write lock.
	76	+ *
	77	+ * @param string $key Unique identifier for rate limiting (e.g., hashed token or IP)
	78	+ * @param int $max_attempts Maximum number of attempts allowed
67	79	* @param int $window_seconds Time window in seconds
68		- * @param string $prefix Optional prefix for the rate limit key
	80	+ * @param string $prefix Optional prefix for the rate limit key
69	81	* @return bool|WP_Error True if under limit, WP_Error if rate limit exceeded
70	82	*/
71	83	public function check_rate_limit($key, $max_attempts, $window_seconds, $prefix = '')
72	84	{
73		- global $wpdb;
	85	+ $full_key = $prefix . $key;
	86	+ $transient_key = $this->get_transient_key($full_key);
	87	+ $now = time();
74	88
75		- $full_key = $prefix . $key;
76		- $now = time();
	89	+ $data = get_transient($transient_key);
77	90
78		- # Get current rate limit data with row-level locking for atomicity
79		- # Using direct database query instead of get_option for reliability
80		- $data = $this->get_rate_limit_data();
81		-
82		- # Initialize entry if not exists or expired
83		- if (!isset($data[$full_key]) || $data[$full_key]['expires_at'] < $now) {
84		- $data[$full_key] = array(
85		- 'attempts' => 1,
	91	+ # Initialize entry if not present or expired
	92	+ if ($data === false || !is_array($data) || !isset($data['expires_at']) || $data['expires_at'] < $now) {
	93	+ $data = array(
	94	+ 'attempts' => 1,
86	95	'first_attempt_at' => $now,
87		- 'expires_at' => $now + $window_seconds,
88		- 'window_seconds' => $window_seconds,
	96	+ 'expires_at' => $now + $window_seconds,
	97	+ 'window_seconds' => $window_seconds,
89	98	);
90		- $this->save_rate_limit_data($data);
	99	+ set_transient($transient_key, $data, $window_seconds);
91	100
92	101	return true;
93	102	}
94	103
95	104	# Check if rate limit exceeded
96		- if ($data[$full_key]['attempts'] >= $max_attempts) {
97		- $remaining_seconds = $data[$full_key]['expires_at'] - $now;
	105	+ if ($data['attempts'] >= $max_attempts) {
	106	+ $remaining_seconds = $data['expires_at'] - $now;
98	107	$remaining_minutes = ceil($remaining_seconds / 60);
99	108
100	109	return new WP_Error(
101	110	'rate_limit_exceeded',
		@@ -105,18 +114,18 @@
105	114	$remaining_minutes > 1 ? 's' : ''
106	115	),
107	116	array(
108	117	'retry_after' => $remaining_seconds,
109		- 'attempts' => $data[$full_key]['attempts'],
	118	+ 'attempts' => $data['attempts'],
110	119	'max_attempts' => $max_attempts,
111	120	)
112	121	);
113	122	}
114	123
115		- # Increment attempt count
116		- $data[$full_key]['attempts']++;
117		- $data[$full_key]['last_attempt_at'] = $now;
118		- $this->save_rate_limit_data($data);
	124	+ # Increment attempt count, preserving the original window end
	125	+ $data['attempts']++;
	126	+ $data['last_attempt_at'] = $now;
	127	+ set_transient($transient_key, $data, max(1, $data['expires_at'] - $now));
119	128
120	129	return true;
121	130	}
122	131
		@@ -172,94 +181,8 @@
172	181	return $this->check_rate_limit($token_hash, $max_attempts, $window_seconds, 'token_');
173	182	}
174	183
175	184	/**
176		- * Get rate limit data from database
177		- *
178		- * Uses direct SQL query to bypass object caching and ensure
179		- * we always get the latest data from the database.
180		- *
181		- * @return array Rate limit data
182		- */
183		- private function get_rate_limit_data()
184		- {
185		- global $wpdb;
186		-
187		- # Bypass object cache by using direct SQL query
188		- $value = $wpdb->get_var(
189		- $wpdb->prepare(
190		- "SELECT option_value FROM {$wpdb->options} WHERE option_name = %s LIMIT 1",
191		- self::OPTION_NAME
192		- )
193		- );
194		-
195		- if ($value === null) {
196		- return array();
197		- }
198		-
199		- $data = maybe_unserialize($value);
200		- return is_array($data) ? $data : array();
201		- }
202		-
203		- /**
204		- * Save rate limit data to database
205		- *
206		- * Uses direct SQL query with ON DUPLICATE KEY UPDATE for atomicity.
207		- *
208		- * @param array $data Rate limit data
209		- * @return bool Success
210		- */
211		- private function save_rate_limit_data($data)
212		- {
213		- global $wpdb;
214		-
215		- $serialized = maybe_serialize($data);
216		-
217		- # Use REPLACE to ensure atomic update (INSERT or UPDATE)
218		- $result = $wpdb->query(
219		- $wpdb->prepare(
220		- "INSERT INTO {$wpdb->options} (option_name, option_value, autoload)
221		- VALUES (%s, %s, 'no')
222		- ON DUPLICATE KEY UPDATE option_value = VALUES(option_value)",
223		- self::OPTION_NAME,
224		- $serialized
225		- )
226		- );
227		-
228		- # Clear any object cache for this option
229		- wp_cache_delete(self::OPTION_NAME, 'options');
230		-
231		- return $result !== false;
232		- }
233		-
234		- /**
235		- * Clean up expired rate limit entries
236		- *
237		- * Called via cron job to prevent database bloat.
238		- *
239		- * @return int Number of entries cleaned up
240		- */
241		- public function cleanup_expired_entries()
242		- {
243		- $data = $this->get_rate_limit_data();
244		- $now = time();
245		- $original_count = count($data);
246		-
247		- # Remove expired entries
248		- $data = array_filter($data, function ($entry) use ($now) {
249		- return isset($entry['expires_at']) && $entry['expires_at'] > $now;
250		- });
251		-
252		- $removed_count = $original_count - count($data);
253		-
254		- if ($removed_count > 0) {
255		- $this->save_rate_limit_data($data);
256		- }
257		-
258		- return $removed_count;
259		- }
260		-
261		- /**
262	185	* Get client IP address
263	186	*
264	187	* Handles various proxy configurations and load balancers.
265	188	*
		@@ -304,16 +227,9 @@
304	227	* @return bool Success
305	228	*/
306	229	public function reset_rate_limit($key, $prefix = '')
307	230	{
308		- $full_key = $prefix . $key;
309		- $data = $this->get_rate_limit_data();
310		-
311		- if (isset($data[$full_key])) {
312		- unset($data[$full_key]);
313		- return $this->save_rate_limit_data($data);
314		- }
315		-
	231	+ delete_transient($this->get_transient_key($prefix . $key));
316	232	return true;
317	233	}
318	234
319	235	/**
		@@ -324,32 +240,22 @@
324	240	* @return array|null Rate limit status or null if not found
325	241	*/
326	242	public function get_rate_limit_status($key, $prefix = '')
327	243	{
328		- $full_key = $prefix . $key;
329		- $data = $this->get_rate_limit_data();
	244	+ $data = get_transient($this->get_transient_key($prefix . $key));
330	245
331		- if (!isset($data[$full_key])) {
	246	+ if ($data === false || !is_array($data)) {
332	247	return null;
333	248	}
334	249
335		- $entry = $data[$full_key];
336	250	$now = time();
337	251
338	252	return array(
339		- 'attempts' => $entry['attempts'],
340		- 'expires_at' => $entry['expires_at'],
341		- 'remaining_seconds' => max(0, $entry['expires_at'] - $now),
342		- 'is_expired' => $entry['expires_at'] < $now,
343		- 'first_attempt_at' => $entry['first_attempt_at'],
344		- 'last_attempt_at' => isset($entry['last_attempt_at']) ? $entry['last_attempt_at'] : null,
	253	+ 'attempts' => $data['attempts'],
	254	+ 'expires_at' => $data['expires_at'],
	255	+ 'remaining_seconds' => max(0, $data['expires_at'] - $now),
	256	+ 'is_expired' => $data['expires_at'] < $now,
	257	+ 'first_attempt_at' => $data['first_attempt_at'],
	258	+ 'last_attempt_at' => isset($data['last_attempt_at']) ? $data['last_attempt_at'] : null,
345	259	);
346	260	}
347	261	}
348		-
349		-/**
350		- * Hook for cron cleanup
351		- */
352		-add_action('metasync_rate_limit_cleanup', function () {
353		- $rate_limiter = Metasync_Rate_Limiter::get_instance();
354		- $rate_limiter->cleanup_expired_entries();
355		-});