class-cachemiddleware.php
6 days ago
class-httpmiddleware.php
6 days ago
class-redirectionmiddleware.php
6 days ago
middleware-interface.php
6 days ago
class-cachemiddleware.php
554 lines
| 1 | <?php |
| 2 | |
| 3 | namespace WordPress\HttpClient\Middleware; |
| 4 | |
| 5 | use RuntimeException; |
| 6 | use WordPress\HttpClient\Client; |
| 7 | use WordPress\HttpClient\Request; |
| 8 | use WordPress\HttpClient\Response; |
| 9 | |
| 10 | final class CacheMiddleware implements MiddlewareInterface { |
| 11 | /** |
| 12 | * @var MiddlewareInterface |
| 13 | */ |
| 14 | private $next_middleware; |
| 15 | |
| 16 | /** |
| 17 | * @var ClientState |
| 18 | */ |
| 19 | private $state; |
| 20 | |
| 21 | private $dir; |
| 22 | |
| 23 | /** @var array<string,array{req:Request,meta:array,file:resource|null,headerDone:bool,done:bool}> */ |
| 24 | private $replay = array(); |
| 25 | |
| 26 | /** |
| 27 | * Writers keyed by spl_object_hash(req). |
| 28 | * |
| 29 | * @var array |
| 30 | */ |
| 31 | private $temp_handle = array(); |
| 32 | private $temp_path = array(); |
| 33 | |
| 34 | public function __construct( $client_state, $next_middleware, $options = array() ) { |
| 35 | $this->next_middleware = $next_middleware; |
| 36 | $this->state = $client_state; |
| 37 | $this->dir = rtrim( $options['cache_dir'], '/' ); |
| 38 | |
| 39 | if ( ! is_dir( $this->dir ) ) { |
| 40 | throw new RuntimeException( sprintf( 'Cache dir %s does not exist or is not a directory', esc_html( $this->dir ) ) ); |
| 41 | } |
| 42 | } |
| 43 | |
| 44 | public function enqueue( Request $request ) { |
| 45 | $meth = strtoupper( $request->method ); |
| 46 | if ( ! in_array( $meth, array( 'GET', 'HEAD' ), true ) ) { |
| 47 | $this->invalidateCache( $request ); |
| 48 | return $this->next_middleware->enqueue( $request ); |
| 49 | } |
| 50 | |
| 51 | [ $key, $meta ] = $this->lookup( $request ); |
| 52 | $request->cache_key = $key; |
| 53 | |
| 54 | if ( $meta && $this->fresh( $meta ) ) { |
| 55 | $this->startReplay( $request, $meta ); |
| 56 | return; |
| 57 | } |
| 58 | |
| 59 | if ( $meta ) { |
| 60 | $this->addValidators( $request, $meta ); |
| 61 | } |
| 62 | |
| 63 | return $this->next_middleware->enqueue( $request ); |
| 64 | } |
| 65 | |
| 66 | public function await_next_event( $requests_ids ): bool { |
| 67 | /* serve cached replay first. */ |
| 68 | $id = array_keys( $this->replay )[0] ?? null; |
| 69 | if ( null !== $id ) { |
| 70 | $this->fromCache( $id ); |
| 71 | |
| 72 | // When done, close the file handle and clean up the replay entry. |
| 73 | if ( $this->replay[ $id ]['done'] ) { |
| 74 | fclose( $this->replay[ $id ]['file'] ); |
| 75 | unset( $this->replay[ $id ] ); |
| 76 | } |
| 77 | return true; |
| 78 | } |
| 79 | |
| 80 | /* drive next middleware. */ |
| 81 | if ( ! $this->next_middleware->await_next_event( $requests_ids ) ) { |
| 82 | return false; |
| 83 | } |
| 84 | |
| 85 | return $this->handleNetwork(); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Cache replay functionality. |
| 90 | */ |
| 91 | private function startReplay( Request $request, array $meta ): void { |
| 92 | $id = spl_object_hash( $request ); |
| 93 | $file_handle = fopen( $this->bodyPath( $request->cache_key, $request->url ), 'rb' ); |
| 94 | $this->replay[ $id ] = array( |
| 95 | 'req' => $request, |
| 96 | 'meta' => $meta, |
| 97 | 'file' => $file_handle, |
| 98 | 'headerDone' => false, |
| 99 | 'done' => false, |
| 100 | ); |
| 101 | } |
| 102 | |
| 103 | private function start304Replay( Request $request, array $meta ): void { |
| 104 | $id = spl_object_hash( $request ); |
| 105 | $file_handle = fopen( $this->bodyPath( $request->cache_key, $request->url ), 'rb' ); |
| 106 | $this->replay[ $id ] = array( |
| 107 | 'req' => $request, |
| 108 | 'meta' => $meta, |
| 109 | 'file' => $file_handle, |
| 110 | 'headerDone' => false, // Still emit headers for 304 replay. |
| 111 | 'done' => false, |
| 112 | 'is304' => true, // Mark as 304 replay. |
| 113 | ); |
| 114 | } |
| 115 | |
| 116 | private function fromCache( string $id ): void { |
| 117 | $context =& $this->replay[ $id ]; |
| 118 | $request = $context['req']; |
| 119 | |
| 120 | if ( ! $context['headerDone'] ) { |
| 121 | $resp = new Response( $request ); |
| 122 | // For 304 replays, return 200 status with cached headers. |
| 123 | if ( isset( $context['is304'] ) && $context['is304'] ) { |
| 124 | $resp->status_code = 200; // Convert 304 to 200 for the client. |
| 125 | } else { |
| 126 | $resp->status_code = $context['meta']['status']; |
| 127 | } |
| 128 | $resp->headers = $context['meta']['headers']; |
| 129 | |
| 130 | $request->response = $resp; |
| 131 | $this->state->event = Client::EVENT_GOT_HEADERS; |
| 132 | $this->state->request = $request; |
| 133 | |
| 134 | $context['headerDone'] = true; |
| 135 | return; |
| 136 | } |
| 137 | |
| 138 | $chunk = fread( $context['file'], 64 * 1024 ); |
| 139 | if ( '' !== $chunk && false !== $chunk ) { |
| 140 | $this->state->event = Client::EVENT_BODY_CHUNK_AVAILABLE; |
| 141 | $this->state->request = $request; |
| 142 | $this->state->response_body_chunk = $chunk; |
| 143 | return; |
| 144 | } |
| 145 | |
| 146 | $context['done'] = true; |
| 147 | $this->state->event = Client::EVENT_FINISHED; |
| 148 | $this->state->request = $request; |
| 149 | |
| 150 | // For 304 replays, we don't want to override the response. |
| 151 | if ( ! isset( $context['is304'] ) || ! $context['is304'] ) { |
| 152 | $request->response = null; |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Network handling functionality. |
| 158 | */ |
| 159 | private function handleNetwork(): bool { |
| 160 | $event = $this->state->event; |
| 161 | $request = $this->state->request; |
| 162 | $response = $request->response; |
| 163 | |
| 164 | /* HEADERS. */ |
| 165 | if ( Client::EVENT_GOT_HEADERS === $event ) { |
| 166 | if ( 304 === $response->status_code && isset( $request->cache_key ) ) { |
| 167 | [ , $meta ] = $this->lookup( $request, $request->cache_key ); |
| 168 | if ( $meta ) { |
| 169 | // For 304, start a special replay that serves cached body. |
| 170 | $this->start304Replay( $request, $meta ); |
| 171 | return true; |
| 172 | } |
| 173 | } |
| 174 | if ( $this->cacheable( $response ) ) { |
| 175 | // Update cache key based on vary headers if present. |
| 176 | $vary = $response->get_header( 'Vary' ); |
| 177 | if ( $vary ) { |
| 178 | $vary_keys = array_map( 'trim', explode( ',', $vary ) ); |
| 179 | $request->cache_key = $this->varyKey( $request, $vary_keys ); |
| 180 | } |
| 181 | |
| 182 | $tmp = $this->tempPath( $request->cache_key ); |
| 183 | |
| 184 | $this->temp_path[ spl_object_hash( $request ) ] = $tmp; |
| 185 | $this->temp_handle[ spl_object_hash( $request ) ] = fopen( $tmp, 'wb' ); |
| 186 | } |
| 187 | return true; |
| 188 | } |
| 189 | /* BODY. */ |
| 190 | if ( Client::EVENT_BODY_CHUNK_AVAILABLE === $event ) { |
| 191 | $chunk = $this->state->response_body_chunk; |
| 192 | $hash = spl_object_hash( $request ); |
| 193 | if ( isset( $this->temp_handle[ $hash ] ) ) { |
| 194 | fwrite( $this->temp_handle[ $hash ], $chunk ); |
| 195 | } |
| 196 | return true; |
| 197 | } |
| 198 | /* FINISH. */ |
| 199 | if ( Client::EVENT_FINISHED === $event ) { |
| 200 | $hash = spl_object_hash( $request ); |
| 201 | if ( isset( $this->temp_handle[ $hash ] ) ) { |
| 202 | fclose( $this->temp_handle[ $hash ] ); |
| 203 | $this->commit( $request, $response, $this->temp_path[ $hash ] ); |
| 204 | unset( $this->temp_handle[ $hash ], $this->temp_path[ $hash ] ); |
| 205 | } |
| 206 | return true; |
| 207 | } |
| 208 | |
| 209 | return true; |
| 210 | } |
| 211 | |
| 212 | /** |
| 213 | * Cache utilities functionality. |
| 214 | */ |
| 215 | private function metaPath( string $key, ?string $url = null ): string { |
| 216 | if ( $url ) { |
| 217 | $url_hash = sha1( $url ); |
| 218 | return "$this->dir/{$url_hash}_{$key}.json"; |
| 219 | } |
| 220 | return "$this->dir/{$key}.json"; |
| 221 | } |
| 222 | |
| 223 | private function bodyPath( string $key, ?string $url = null ): string { |
| 224 | if ( $url ) { |
| 225 | $url_hash = sha1( $url ); |
| 226 | return "$this->dir/{$url_hash}_{$key}.body"; |
| 227 | } |
| 228 | return "$this->dir/{$key}.body"; |
| 229 | } |
| 230 | |
| 231 | private function tempPath( string $key ): string { |
| 232 | return "$this->dir/{$key}.tmp"; |
| 233 | } |
| 234 | |
| 235 | private function varyKey( Request $request, ?array $vary_keys ): string { |
| 236 | $parts = array( $request->url ); |
| 237 | if ( $vary_keys ) { |
| 238 | // Build a lowercased map of headers for case-insensitive lookup. |
| 239 | $header_map = array(); |
| 240 | foreach ( $request->headers as $k => $v ) { |
| 241 | $header_map[ strtolower( $k ) ] = $v; |
| 242 | } |
| 243 | foreach ( $vary_keys as $header_name ) { |
| 244 | $header_lc = strtolower( $header_name ); |
| 245 | $header_value = $header_map[ $header_lc ] ?? ''; |
| 246 | $parts[] = $header_lc . ':' . $header_value; |
| 247 | } |
| 248 | } |
| 249 | return sha1( implode( '|', $parts ) ); |
| 250 | } |
| 251 | |
| 252 | /** @return array{string,array|null} */ |
| 253 | public function lookup( Request $request, ?string $forced = null ): array { |
| 254 | if ( $forced && is_file( $this->metaPath( $forced, $request->url ) ) ) { |
| 255 | return array( $forced, json_decode( file_get_contents( $this->metaPath( $forced, $request->url ) ), true ) ); |
| 256 | } |
| 257 | |
| 258 | // Look for cache files that match this URL. |
| 259 | $url_hash = sha1( $request->url ); |
| 260 | $glob = glob( $this->dir . '/' . $url_hash . '_*.json' ); |
| 261 | foreach ( $glob as $meta_path ) { |
| 262 | $meta = json_decode( file_get_contents( $meta_path ), true ); |
| 263 | $expected_key = $this->varyKey( $request, $meta['vary'] ?? array() ); |
| 264 | $actual_filename = basename( $meta_path, '.json' ); |
| 265 | $expected_filename = $url_hash . '_' . $expected_key; |
| 266 | |
| 267 | if ( $actual_filename === $expected_filename ) { |
| 268 | return array( $expected_key, $meta ); |
| 269 | } |
| 270 | } |
| 271 | |
| 272 | return array( $this->varyKey( $request, null ), null ); |
| 273 | } |
| 274 | |
| 275 | private function fresh( array $meta ): bool { |
| 276 | $now = time(); |
| 277 | |
| 278 | // Check for must-revalidate directive - if present, never consider fresh without explicit expiry. |
| 279 | $cache_control = $meta['headers']['cache-control'] ?? ''; |
| 280 | $directives = self::directives( $cache_control ); |
| 281 | if ( isset( $directives['must-revalidate'] ) ) { |
| 282 | // With must-revalidate, only consider fresh if we have explicit expiry info. |
| 283 | if ( isset( $meta['max_age'] ) && isset( $meta['stored_at'] ) ) { |
| 284 | $fresh = ( $meta['stored_at'] + (int) $meta['max_age'] ) > $now; |
| 285 | return $fresh; |
| 286 | } |
| 287 | if ( isset( $meta['s_maxage'] ) && isset( $meta['stored_at'] ) ) { |
| 288 | $fresh = ( $meta['stored_at'] + (int) $meta['s_maxage'] ) > $now; |
| 289 | return $fresh; |
| 290 | } |
| 291 | if ( isset( $meta['expires'] ) ) { |
| 292 | $expires = is_numeric( $meta['expires'] ) ? (int) $meta['expires'] : strtotime( $meta['expires'] ); |
| 293 | if ( false !== $expires ) { |
| 294 | $fresh = $expires > $now; |
| 295 | return $fresh; |
| 296 | } |
| 297 | } |
| 298 | // With must-revalidate, don't use heuristic caching. |
| 299 | return false; |
| 300 | } |
| 301 | |
| 302 | // If explicit expiry timestamp is set, use it. |
| 303 | if ( isset( $meta['expires'] ) ) { |
| 304 | $expires = is_numeric( $meta['expires'] ) ? (int) $meta['expires'] : strtotime( $meta['expires'] ); |
| 305 | if ( false !== $expires ) { |
| 306 | $fresh = $expires > $now; |
| 307 | return $fresh; |
| 308 | } |
| 309 | } |
| 310 | |
| 311 | // If explicit TTL (absolute timestamp) is set, use it. |
| 312 | if ( isset( $meta['ttl'] ) ) { |
| 313 | if ( is_numeric( $meta['ttl'] ) ) { |
| 314 | $fresh = (int) $meta['ttl'] > $now; |
| 315 | return $fresh; |
| 316 | } |
| 317 | } |
| 318 | |
| 319 | // If s-maxage is set, check if still valid (takes precedence over max-age). |
| 320 | if ( isset( $meta['s_maxage'] ) && isset( $meta['stored_at'] ) ) { |
| 321 | $fresh = ( $meta['stored_at'] + (int) $meta['s_maxage'] ) > $now; |
| 322 | return $fresh; |
| 323 | } |
| 324 | |
| 325 | // If max_age is set, check if still valid. |
| 326 | if ( isset( $meta['max_age'] ) && isset( $meta['stored_at'] ) ) { |
| 327 | $fresh = ( $meta['stored_at'] + (int) $meta['max_age'] ) > $now; |
| 328 | return $fresh; |
| 329 | } |
| 330 | |
| 331 | // Heuristic: if Last-Modified is present, cache for 10% of its age at storage time. |
| 332 | if ( isset( $meta['last_modified'] ) && isset( $meta['stored_at'] ) ) { |
| 333 | $lm = is_numeric( $meta['last_modified'] ) ? (int) $meta['last_modified'] : strtotime( $meta['last_modified'] ); |
| 334 | if ( false !== $lm ) { |
| 335 | $age = $meta['stored_at'] - $lm; |
| 336 | $heuristic_lifetime = (int) max( 0, $age / 10 ); |
| 337 | $fresh = ( $meta['stored_at'] + $heuristic_lifetime ) > $now; |
| 338 | return $fresh; |
| 339 | } |
| 340 | } |
| 341 | |
| 342 | // Not fresh by any rule. |
| 343 | return false; |
| 344 | } |
| 345 | |
| 346 | private function cacheable( Response $response ): bool { |
| 347 | return self::response_is_cacheable( $response ); |
| 348 | } |
| 349 | |
| 350 | private function addValidators( Request $request, array $meta ): void { |
| 351 | if ( ! empty( $meta['etag'] ) ) { |
| 352 | $request->headers['if-none-match'] = $meta['etag']; |
| 353 | } |
| 354 | if ( ! empty( $meta['last_modified'] ) ) { |
| 355 | $request->headers['if-modified-since'] = $meta['last_modified']; |
| 356 | } |
| 357 | } |
| 358 | |
| 359 | protected function commit( Request $request, Response $response, string $temp_file ) { |
| 360 | $url = $request->url; |
| 361 | $meta = array( |
| 362 | 'url' => $url, |
| 363 | 'status' => $response->status_code, |
| 364 | 'headers' => $response->headers, |
| 365 | 'stored_at' => time(), |
| 366 | 'etag' => $response->get_header( 'ETag' ), |
| 367 | 'last_modified' => $response->get_header( 'Last-Modified' ), |
| 368 | ); |
| 369 | |
| 370 | // Check for Vary header and store vary keys. |
| 371 | $vary = $response->get_header( 'Vary' ); |
| 372 | if ( $vary ) { |
| 373 | $meta['vary'] = array_map( 'trim', explode( ',', $vary ) ); |
| 374 | } |
| 375 | |
| 376 | // Parse Cache-Control for max-age, if present. |
| 377 | $cache_control = $response->get_header( 'Cache-Control' ); |
| 378 | if ( $cache_control ) { |
| 379 | $directives = self::directives( $cache_control ); |
| 380 | if ( isset( $directives['max-age'] ) && is_int( $directives['max-age'] ) ) { |
| 381 | $meta['max_age'] = $directives['max-age']; |
| 382 | } |
| 383 | if ( isset( $directives['s-maxage'] ) && is_int( $directives['s-maxage'] ) ) { |
| 384 | $meta['s_maxage'] = $directives['s-maxage']; |
| 385 | } |
| 386 | } |
| 387 | |
| 388 | // Determine file paths. |
| 389 | $key = $request->cache_key; |
| 390 | $body_file = $this->bodyPath( $key, $url ); |
| 391 | $meta_file = $this->metaPath( $key, $url ); |
| 392 | |
| 393 | // Atomically replace/rename the temp body file to final cache file. |
| 394 | if ( ! rename( $temp_file, $body_file ) ) { |
| 395 | // Handle error (e.g., log failure and abort caching). |
| 396 | return; |
| 397 | } |
| 398 | |
| 399 | // Write metadata with exclusive lock. |
| 400 | $fp = fopen( $meta_file, 'c' ); |
| 401 | if ( $fp ) { |
| 402 | flock( $fp, LOCK_EX ); |
| 403 | ftruncate( $fp, 0 ); |
| 404 | // Serialize or encode CacheEntry (e.g., JSON). |
| 405 | $meta_data = json_encode( $meta ); |
| 406 | fwrite( $fp, $meta_data ); |
| 407 | fflush( $fp ); |
| 408 | flock( $fp, LOCK_UN ); |
| 409 | fclose( $fp ); |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | public function invalidateCache( Request $request ): void { |
| 414 | // Generate cache key if not already set. |
| 415 | if ( ! isset( $request->cache_key ) ) { |
| 416 | [ $key, ] = $this->lookup( $request ); |
| 417 | $request->cache_key = $key; |
| 418 | } |
| 419 | |
| 420 | $key = $request->cache_key; |
| 421 | $body_file = $this->bodyPath( $key, $request->url ); |
| 422 | $meta_file = $this->metaPath( $key, $request->url ); |
| 423 | |
| 424 | // Optionally, acquire lock on meta file to prevent concurrent writes. |
| 425 | $fp = @fopen( $meta_file, 'c' ); |
| 426 | if ( $fp ) { |
| 427 | flock( $fp, LOCK_EX ); |
| 428 | } |
| 429 | |
| 430 | // Delete cache files if they exist. |
| 431 | @unlink( $body_file ); |
| 432 | if ( 'Windows' === PHP_OS_FAMILY && PHP_VERSION_ID < 70300 && isset( $fp ) && $fp ) { |
| 433 | // On Windows, PHP 7.2 or earlier can't "unlink()" files with handles in use. |
| 434 | // In that case, we need to first release the lock, and then unlink the file. |
| 435 | flock( $fp, LOCK_UN ); |
| 436 | fclose( $fp ); |
| 437 | unset( $fp ); |
| 438 | } |
| 439 | @unlink( $meta_file ); |
| 440 | |
| 441 | // Also remove any temp files for this entry. |
| 442 | foreach ( glob( $body_file . '.tmp*' ) as $tmp ) { |
| 443 | @unlink( $tmp ); |
| 444 | } |
| 445 | if ( isset( $fp ) && $fp ) { |
| 446 | flock( $fp, LOCK_UN ); |
| 447 | fclose( $fp ); |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | |
| 452 | /** Return ['no-store'=>true, 'max-age'=>60, …] */ |
| 453 | public static function directives( ?string $value ): array { |
| 454 | if ( null === $value ) { |
| 455 | return array(); |
| 456 | } |
| 457 | $out = array(); |
| 458 | |
| 459 | // Handle quoted values properly by not splitting on commas inside quotes. |
| 460 | $parts = array(); |
| 461 | $current = ''; |
| 462 | $in_quotes = false; |
| 463 | $quote_char = null; |
| 464 | |
| 465 | for ( $i = 0; $i < strlen( $value ); $i++ ) { |
| 466 | $char = $value[ $i ]; |
| 467 | |
| 468 | if ( ! $in_quotes && ( '"' === $char || "'" === $char ) ) { |
| 469 | $in_quotes = true; |
| 470 | $quote_char = $char; |
| 471 | $current .= $char; |
| 472 | } elseif ( $in_quotes && $char === $quote_char ) { |
| 473 | $in_quotes = false; |
| 474 | $quote_char = null; |
| 475 | $current .= $char; |
| 476 | } elseif ( ! $in_quotes && ',' === $char ) { |
| 477 | $parts[] = trim( $current ); |
| 478 | $current = ''; |
| 479 | } else { |
| 480 | $current .= $char; |
| 481 | } |
| 482 | } |
| 483 | |
| 484 | if ( '' !== $current ) { |
| 485 | $parts[] = trim( $current ); |
| 486 | } |
| 487 | |
| 488 | foreach ( $parts as $part ) { |
| 489 | $part = trim( $part ); |
| 490 | if ( '' === $part ) { |
| 491 | continue; |
| 492 | } |
| 493 | if ( false !== strpos( $part, '=' ) ) { |
| 494 | [ $k, $v ] = array_map( 'trim', explode( '=', $part, 2 ) ); |
| 495 | $out[ strtolower( $k ) ] = ctype_digit( $v ) ? (int) $v : $v; |
| 496 | } else { |
| 497 | $out[ strtolower( $part ) ] = true; |
| 498 | } |
| 499 | } |
| 500 | |
| 501 | return $out; |
| 502 | } |
| 503 | |
| 504 | public static function response_is_cacheable( Response $r ): bool { |
| 505 | $req = $r->request; |
| 506 | if ( 'GET' !== $req->method && 'HEAD' !== $req->method ) { |
| 507 | return false; |
| 508 | } |
| 509 | |
| 510 | // Allow caching of successful responses and redirects. |
| 511 | if ( ! ( ( $r->status_code >= 200 && $r->status_code < 300 ) || ( $r->status_code >= 300 && $r->status_code < 400 ) ) ) { |
| 512 | return false; |
| 513 | } |
| 514 | |
| 515 | $d = self::directives( $r->get_header( 'cache-control' ) ); |
| 516 | if ( isset( $d['no-store'] ) ) { |
| 517 | return false; |
| 518 | } |
| 519 | |
| 520 | // Check for explicit freshness indicators, but also validate they're not expired. |
| 521 | if ( isset( $d['max-age'] ) ) { |
| 522 | // Don't cache responses with max-age=0. |
| 523 | if ( is_int( $d['max-age'] ) && $d['max-age'] <= 0 ) { |
| 524 | return false; |
| 525 | } |
| 526 | return true; |
| 527 | } |
| 528 | |
| 529 | if ( isset( $d['s-maxage'] ) ) { |
| 530 | // Don't cache responses with s-maxage=0. |
| 531 | if ( is_int( $d['s-maxage'] ) && $d['s-maxage'] <= 0 ) { |
| 532 | return false; |
| 533 | } |
| 534 | return true; |
| 535 | } |
| 536 | |
| 537 | if ( $r->get_header( 'expires' ) ) { |
| 538 | // Check if expires header indicates an already expired response. |
| 539 | $expires = strtotime( $r->get_header( 'expires' ) ); |
| 540 | if ( false !== $expires && $expires <= time() ) { |
| 541 | return false; // Don't cache already expired responses. |
| 542 | } |
| 543 | return true; |
| 544 | } |
| 545 | |
| 546 | // Cache responses with validation headers (ETag or Last-Modified). |
| 547 | if ( $r->get_header( 'etag' ) || $r->get_header( 'last-modified' ) ) { |
| 548 | return true; |
| 549 | } |
| 550 | |
| 551 | return false; |
| 552 | } |
| 553 | } |
| 554 |