CRM/Utils/Http.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | CiviCRM version 5                                                  |
   5  +--------------------------------------------------------------------+
   6  | Copyright CiviCRM LLC (c) 2004-2018                                |
   7  +--------------------------------------------------------------------+
   8  | This file is a part of CiviCRM.                                    |
   9  |                                                                    |
  10  | CiviCRM is free software; you can copy, modify, and distribute it  |
  11  | under the terms of the GNU Affero General Public License           |
  12  | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
  13  |                                                                    |
  14  | CiviCRM is distributed in the hope that it will be useful, but     |
  15  | WITHOUT ANY WARRANTY; without even the implied warranty of         |
  16  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               |
  17  | See the GNU Affero General Public License for more details.        |
  18  |                                                                    |
  19  | You should have received a copy of the GNU Affero General Public   |
  20  | License and the CiviCRM Licensing Exception along                  |
  21  | with this program; if not, contact CiviCRM LLC                     |
  22  | at info[AT]civicrm[DOT]org. If you have questions about the        |
  23  | GNU Affero General Public License or the licensing of CiviCRM,     |
  24  | see the CiviCRM license FAQ at http://civicrm.org/licensing        |
  25  +--------------------------------------------------------------------+
  26  */
  27
  28 /**
  29  *
  30  * @package CiviCRM_Hook
  31  * @copyright CiviCRM LLC (c) 2004-2018
  32  */
  33 class CRM_Utils_Http {
  34
  35   /**
  36    * Parse the expiration time from a series of HTTP headers.
  37    *
  38    * @param array $headers
  39    * @return int|NULL
  40    *   Expiration tme as seconds since epoch, or NULL if not cacheable.
  41    */
  42   public static function parseExpiration($headers) {
  43     $headers = CRM_Utils_Array::rekey($headers, function ($k, $v) {
  44       return strtolower($k);
  45     });
  46
  47     if (!empty($headers['cache-control'])) {
  48       $cc = self::parseCacheControl($headers['cache-control']);
  49       if ($cc['max-age'] && is_numeric($cc['max-age'])) {
  50         return CRM_Utils_Time::getTimeRaw() + $cc['max-age'];
  51       }
  52     }
  53
  54     return NULL;
  55   }
  56
  57   /**
  58    * @param string $value
  59    *   Ex: "max-age=86400, public".
  60    * @return array
  61    *   Ex: Array("max-age"=>86400, "public"=>1).
  62    */
  63   public static function parseCacheControl($value) {
  64     $result = array();
  65
  66     $parts = preg_split('/, */', $value);
  67     foreach ($parts as $part) {
  68       if (strpos($part, '=') !== FALSE) {
  69         list ($key, $value) = explode('=', $part, 2);
  70         $result[$key] = $value;
  71       }
  72       else {
  73         $result[$part] = TRUE;
  74       }
  75     }
  76
  77     return $result;
  78   }
  79
  80 }