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<?php |
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/** |
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* This is a lightweight proxy for serving images, generally meant to be used alongside SSL |
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* |
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* Simple Machines Forum (SMF) |
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* |
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* @package SMF |
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* @author Simple Machines http://www.simplemachines.org |
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* @copyright 2018 Simple Machines and individual contributors |
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* @license http://www.simplemachines.org/about/smf/license.php BSD |
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* |
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* @version 2.1 Beta 4 |
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*/ |
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if (!defined('SMF')) |
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define('SMF', 'proxy'); |
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global $proxyhousekeeping; |
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/** |
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* Class ProxyServer |
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*/ |
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class ProxyServer |
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{ |
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/** @var bool $enabled Whether or not this is enabled */ |
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protected $enabled; |
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/** @var int $maxSize The maximum size for files to cache */ |
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protected $maxSize; |
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/** @var string $secret A secret code used for hashing */ |
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protected $secret; |
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/** @var string The cache directory */ |
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protected $cache; |
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/** @var int $maxDays until enties get deleted */ |
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protected $maxDays; |
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/** |
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* Constructor, loads up the Settings for the proxy |
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* |
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* @access public |
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*/ |
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public function __construct() |
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{ |
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global $image_proxy_enabled, $image_proxy_maxsize, $image_proxy_secret, $cachedir, $sourcedir; |
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require_once(dirname(__FILE__) . '/Settings.php'); |
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require_once($sourcedir . '/Subs.php'); |
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// Turn off all error reporting; any extra junk makes for an invalid image. |
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error_reporting(0); |
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$this->enabled = (bool) $image_proxy_enabled; |
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$this->maxSize = (int) $image_proxy_maxsize; |
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$this->secret = (string) $image_proxy_secret; |
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$this->cache = $cachedir . '/images'; |
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$this->maxDays = 5; |
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} |
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/** |
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* Checks whether the request is valid or not |
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* |
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* @access public |
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* @return bool Whether the request is valid |
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*/ |
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public function checkRequest() |
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{ |
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if (!$this->enabled) |
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return false; |
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// Try to create the image cache directory if it doesn't exist |
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if (!file_exists($this->cache)) |
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if (!mkdir($this->cache) || !copy(dirname($this->cache) . '/index.php', $this->cache . '/index.php')) |
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return false; |
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// Basic sanity check |
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$_GET['request'] = validate_iri($_GET['request']); |
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// We aren't going anywhere without these |
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if (empty($_GET['hash']) || empty($_GET['request'])) |
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return false; |
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$hash = $_GET['hash']; |
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$request = $_GET['request']; |
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if (md5($request . $this->secret) != $hash) |
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return false; |
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// Ensure any non-ASCII characters in the URL are encoded correctly |
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$request = iri_to_url($request); |
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// Attempt to cache the request if it doesn't exist |
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if (!$this->isCached($request)) |
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return $this->cacheImage($request); |
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return true; |
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} |
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/** |
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* Serves the request |
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* |
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* @access public |
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* @return void |
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*/ |
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public function serve() |
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{ |
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$request = $_GET['request']; |
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$cached_file = $this->getCachedPath($request); |
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$cached = json_decode(file_get_contents($cached_file), true); |
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// Did we get an error when trying to fetch the image |
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$response = $this->checkRequest(); |
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if ($response === -1) |
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{ |
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// Throw a 404 |
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header('HTTP/1.0 404 Not Found'); |
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exit; |
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} |
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// Right, image not cached? Simply redirect, then. |
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if ($response === 0) |
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{ |
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$this::redirectexit($request); |
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} |
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$time = time(); |
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// Is the cache expired? |
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if (!$cached || $time - $cached['time'] > ($this->maxDays * 86400)) |
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{ |
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@unlink($cached_file); |
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if ($this->checkRequest()) |
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$this->serve(); |
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$this::redirectexit($request); |
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} |
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$eTag = '"' . substr(sha1($request) . $cached['time'], 0, 64) . '"'; |
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View Code Duplication |
if (!empty($_SERVER['HTTP_IF_NONE_MATCH']) && strpos($_SERVER['HTTP_IF_NONE_MATCH'], $eTag) !== false) |
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{ |
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header('HTTP/1.1 304 Not Modified'); |
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exit; |
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} |
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// Make sure we're serving an image |
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$contentParts = explode('/', !empty($cached['content_type']) ? $cached['content_type'] : ''); |
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if ($contentParts[0] != 'image') |
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exit; |
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$max_age = $time - $cached['time'] + (5 * 86400); |
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header('content-type: ' . $cached['content_type']); |
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header('content-length: ' . $cached['size']); |
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header('cache-control: public, max-age=' . $max_age ); |
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header('last-modified: ' . gmdate('D, d M Y H:i:s', $cached['time']) . ' GMT'); |
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header('etag: ' . $eTag); |
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echo base64_decode($cached['body']); |
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} |
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/** |
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* Returns the request's hashed filepath |
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* |
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* @access public |
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* @param string $request The request to get the path for |
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* @return string The hashed filepath for the specified request |
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*/ |
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protected function getCachedPath($request) |
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{ |
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return $this->cache . '/' . sha1($request . $this->secret); |
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} |
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/** |
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* Check whether the image exists in local cache or not |
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* |
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* @access protected |
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* @param string $request The image to check for in the cache |
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* @return bool Whether or not the requested image is cached |
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*/ |
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protected function isCached($request) |
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{ |
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return file_exists($this->getCachedPath($request)); |
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} |
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/** |
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* Attempts to cache the image while validating it |
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* |
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* @access protected |
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* @param string $request The image to cache/validate |
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* @return int -1 error, 0 too big, 1 valid image |
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*/ |
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protected function cacheImage($request) |
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{ |
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$dest = $this->getCachedPath($request); |
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$ext = strtolower(pathinfo(parse_url($request, PHP_URL_PATH), PATHINFO_EXTENSION)); |
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$image = fetch_web_data($request); |
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// Looks like nobody was home |
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if (empty($image)) |
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return -1; |
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// What kind of file did they give us? |
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$finfo = finfo_open(FILEINFO_MIME_TYPE); |
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$mime_type = finfo_buffer($finfo, $image); |
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// SVG needs a little extra care |
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if ($ext == 'svg' && $mime_type == 'text/plain') |
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$mime_type = 'image/svg+xml'; |
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// Make sure the url is returning an image |
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if (strpos($mime_type, 'image/') !== 0) |
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return -1; |
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// Validate the filesize |
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$size = strlen($image); |
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if ($size > ($this->maxSize * 1024)) |
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return 0; |
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// Cache it for later |
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return file_put_contents($dest, json_encode(array( |
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'content_type' => $mime_type, |
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'size' => $size, |
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'time' => time(), |
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'body' => base64_encode($image), |
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))) === false ? -1 : 1; |
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} |
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/** |
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* Static helper function to redirect a request |
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* |
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* @access public |
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* @param type $request |
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* @return void |
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*/ |
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static public function redirectexit($request) |
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{ |
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header('Location: ' . $request, false, 301); |
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exit; |
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} |
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/** |
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* Delete all old entries |
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* |
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* @access public |
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* @return void |
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*/ |
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public function housekeeping() |
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{ |
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$path = $this->cache . '/'; |
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if ($handle = opendir($path)) |
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{ |
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while (false !== ($file = readdir($handle))) |
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{ |
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$filelastmodified = filemtime($path . $file); |
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if ((time() - $filelastmodified) > ($this->maxDays * 86400)) |
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{ |
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unlink($path . $file); |
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} |
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} |
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closedir($handle); |
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} |
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} |
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} |
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if (empty($proxyhousekeeping)) |
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{ |
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$proxy = new ProxyServer(); |
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$proxy->serve(); |
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} |
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?> |
Instead of relying on
globalstate, we recommend one of these alternatives:1. Pass all data via parameters
2. Create a class that maintains your state