CRM/Utils/Http.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | Copyright CiviCRM LLC. All rights reserved.                        |
   5  |                                                                    |
   6  | This work is published under the GNU AGPLv3 license with some      |
   7  | permitted exceptions and without any warranty. For full license    |
   8  | and copyright information, see https://civicrm.org/licensing       |
   9  +--------------------------------------------------------------------+
  10  */
  11
  12 /**
  13  *
  14  * @package CiviCRM_Hook
  15  * @copyright CiviCRM LLC https://civicrm.org/licensing
  16  */
  17 class CRM_Utils_Http {
  18
  19   /**
  20    * Parse the expiration time from a series of HTTP headers.
  21    *
  22    * @param array $headers
  23    * @return int|null
  24    *   Expiration tme as seconds since epoch, or NULL if not cacheable.
  25    */
  26   public static function parseExpiration($headers) {
  27     $headers = CRM_Utils_Array::rekey($headers, function ($k, $v) {
  28       return strtolower($k);
  29     });
  30
  31     if (!empty($headers['cache-control'])) {
  32       $cc = self::parseCacheControl($headers['cache-control']);
  33       if ($cc['max-age'] && is_numeric($cc['max-age'])) {
  34         return CRM_Utils_Time::getTimeRaw() + $cc['max-age'];
  35       }
  36     }
  37
  38     return NULL;
  39   }
  40
  41   /**
  42    * @param string $value
  43    *   Ex: "max-age=86400, public".
  44    * @return array
  45    *   Ex: Array("max-age"=>86400, "public"=>1).
  46    */
  47   public static function parseCacheControl($value) {
  48     $result = [];
  49
  50     $parts = preg_split('/, */', $value);
  51     foreach ($parts as $part) {
  52       if (strpos($part, '=') !== FALSE) {
  53         list ($key, $value) = explode('=', $part, 2);
  54         $result[$key] = $value;
  55       }
  56       else {
  57         $result[$part] = TRUE;
  58       }
  59     }
  60
  61     return $result;
  62   }
  63
  64 }