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   1  <?php
   2  /*
   3   * Limb PHP Framework
   4   *
   5   * @link http://limb-project.com 
   6   * @copyright  Copyright &copy; 2004-2007 BIT(http://bit-creative.com)
   7   * @license    LGPL http://www.gnu.org/copyleft/lesser.html 
   8   */
   9  //inspired by http://alexandre.alapetite.net/doc-alex/php-http-304/

  10  
  11  define('LIMB_HTTP_CACHE_TYPE_PRIVATE', 0);
  12  define('LIMB_HTTP_CACHE_TYPE_PUBLIC', 1);
  13  
  14  /**

  15   * class lmbHttpCache.

  16   *

  17   * @package net

  18   * @version $Id: lmbHttpCache.class.php 5945 2007-06-06 08:31:43Z pachanga $

  19   */
  20  class lmbHttpCache
  21  {
  22    protected $etag;
  23    protected $last_modified_time;
  24    protected $cache_time;
  25    protected $cache_type;
  26  
  27    function __construct()
  28    {
  29      $this->reset();
  30    }
  31  
  32    function reset()
  33    {
  34      $this->last_modified_time = time();
  35      $this->etag = null;
  36      $this->cache_time = 0;
  37      $this->cache_type = LIMB_HTTP_CACHE_TYPE_PRIVATE;
  38    }
  39  
  40    function checkAndWrite($response)
  41    {
  42      if($this->is412())
  43      {
  44        $this->_write412Response($response);
  45        return true;
  46      }
  47      elseif($this->is304())
  48      {
  49        $this->_write304Response($response);
  50        return true;
  51      }
  52      else
  53      {
  54        $this->_writeCachingResponse($response);
  55  
  56        return isset($_SERVER['REQUEST_METHOD']) && $_SERVER['REQUEST_METHOD'] == 'HEAD'; //rfc2616-sec9.html#sec9.4

  57      }
  58    }
  59  
  60    function is412()
  61    {
  62      if (isset($_SERVER['HTTP_IF_MATCH'])) //rfc2616-sec14.html#sec14.24
  63      {
  64        $etag_client = stripslashes($_SERVER['HTTP_IF_MATCH']);
  65        return (($etag_client != '*') &&  (strpos($etag_client, $this->getEtag()) === false));
  66      }
  67  
  68      if (isset($_SERVER['HTTP_IF_UNMODIFIED_SINCE'])) //http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.28
  69      {
  70        return (strcasecmp($_SERVER['HTTP_IF_UNMODIFIED_SINCE'], $this->formatLastModifiedTime()) != 0);
  71      }
  72  
  73      return false;
  74    }
  75  
  76    function is304()
  77    {
  78      if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) //rfc2616-sec14.html#sec14.25 //rfc1945.txt
  79      {
  80        return ($_SERVER['HTTP_IF_MODIFIED_SINCE'] == $this->formatLastModifiedTime());
  81      }
  82  
  83      if (isset($_SERVER['HTTP_IF_NONE_MATCH'])) //rfc2616-sec14.html#sec14.26
  84      {
  85        $etag_client = stripslashes($_SERVER['HTTP_IF_NONE_MATCH']);
  86        return (($etag_client == $this->getEtag()) ||  ($etag_client == '*'));
  87      }
  88  
  89      return false;
  90    }
  91  
  92    protected function _write412Response($response)
  93    {
  94      $response->header('HTTP/1.1 412 Precondition Failed');
  95      $response->header('Cache-Control: protected, max-age=0, must-revalidate');
  96      $response->header('Content-Type: text/plain');
  97  
  98      $response->write("HTTP/1.1 Error 412 Precondition Failed: Precondition request failed positive evaluation\n");
  99    }
 100  
 101    protected function _write304Response($response)
 102    {
 103      $response->header('HTTP/1.0 304 Not Modified');
 104      $response->header('Etag: ' . $this->getEtag());
 105      $response->header('Pragma: ');
 106      $response->header('Cache-Control: ');
 107      $response->header('Last-Modified: ');
 108      $response->header('Expires: ');
 109    }
 110  
 111    protected function _writeCachingResponse($response)
 112    {
 113      $response->header('Cache-Control: ' . $this->_getCacheControl()); //rfc2616-sec14.html#sec14.9

 114      $response->header('Last-Modified: ' . $this->formatLastModifiedTime());
 115      $response->header('Etag: ' . $this->getEtag());
 116      $response->header('Pragma: ');
 117      $response->header('Expires: ');
 118    }
 119  
 120    protected function _getCacheControl()
 121    {
 122      if ($this->cache_time == 0)
 123        $cache = 'protected, must-revalidate, ';
 124      elseif ($this->cache_type == LIMB_HTTP_CACHE_TYPE_PRIVATE)
 125        $cache = 'protected, ';
 126      elseif ($this->cache_type == LIMB_HTTP_CACHE_TYPE_PUBLIC)
 127        $cache = 'public, ';
 128      else
 129        $cache = '';
 130      $cache .= 'max-age=' . floor($this->cache_time);
 131      return $cache;
 132    }
 133  
 134    function formatLastModifiedTime()
 135    {
 136      return $this->_formatGmtTime($this->last_modified_time);
 137    }
 138  
 139    protected function _formatGmtTime($time)
 140    {
 141      return gmdate('D, d M Y H:i:s \G\M\T', $time);
 142    }
 143  
 144    function setLastModifiedTime($last_modified_time)
 145    {
 146      $this->last_modified_time = $last_modified_time;
 147    }
 148  
 149    function getLastModifiedTime()
 150    {
 151      return $this->last_modified_time;
 152    }
 153  
 154    function setEtag($etag)
 155    {
 156      $this->etag = $etag;
 157    }
 158  
 159    function getEtag()
 160    {
 161      if($this->etag)
 162        return $this->etag;
 163  
 164      //rfc2616-sec14.html#sec14.19 //='"0123456789abcdef0123456789abcdef"'

 165      if (isset($_SERVER['QUERY_STRING']))
 166        $query = '?' . $_SERVER['QUERY_STRING'];
 167      else
 168        $query = '';
 169  
 170      $this->etag = '"' . md5($this->_getScriptName() . $query . '#' . $this->last_modified_time ) . '"';
 171  
 172      return $this->etag;
 173    }
 174  
 175    protected function _getScriptName()
 176    {
 177      if (isset($_SERVER['SCRIPT_FILENAME']))
 178        return $_SERVER['SCRIPT_FILENAME'];
 179      elseif (isset($_SERVER['PATH_TRANSLATED']))
 180        return $_SERVER['PATH_TRANSLATED'];
 181      else
 182        return '';
 183    }
 184  
 185    function setCacheTime($cache_time)
 186    {
 187      $this->cache_time = $cache_time;
 188    }
 189  
 190    function getCacheTime()
 191    {
 192      return $this->cache_time;
 193    }
 194  
 195    function setCacheType($cache_type)
 196    {
 197      $this->cache_type = $cache_type;
 198    }
 199  
 200    function getCacheType()
 201    {
 202      return $this->cache_type;
 203    }
 204  }
 205  
 206  ?>