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   1  <?php
   2  
   3  /**
   4   * Registry for retrieving specific URI scheme validator objects.
   5   */
   6  class HTMLPurifier_URISchemeRegistry
   7  {
   8  
   9      /**
  10       * Retrieve sole instance of the registry.
  11       * @param HTMLPurifier_URISchemeRegistry $prototype Optional prototype to overload sole instance with,
  12       *                   or bool true to reset to default registry.
  13       * @return HTMLPurifier_URISchemeRegistry
  14       * @note Pass a registry object $prototype with a compatible interface and
  15       *       the function will copy it and return it all further times.
  16       */
  17      public static function instance($prototype = null)
  18      {
  19          static $instance = null;
  20          if ($prototype !== null) {
  21              $instance = $prototype;
  22          } elseif ($instance === null || $prototype == true) {
  23              $instance = new HTMLPurifier_URISchemeRegistry();
  24          }
  25          return $instance;
  26      }
  27  
  28      /**
  29       * Cache of retrieved schemes.
  30       * @type HTMLPurifier_URIScheme[]
  31       */
  32      protected $schemes = array();
  33  
  34      /**
  35       * Retrieves a scheme validator object
  36       * @param string $scheme String scheme name like http or mailto
  37       * @param HTMLPurifier_Config $config
  38       * @param HTMLPurifier_Context $context
  39       * @return HTMLPurifier_URIScheme
  40       */
  41      public function getScheme($scheme, $config, $context)
  42      {
  43          if (!$config) {
  44              $config = HTMLPurifier_Config::createDefault();
  45          }
  46  
  47          // important, otherwise attacker could include arbitrary file
  48          $allowed_schemes = $config->get('URI.AllowedSchemes');
  49          if (!$config->get('URI.OverrideAllowedSchemes') &&
  50              !isset($allowed_schemes[$scheme])
  51          ) {
  52              return;
  53          }
  54  
  55          if (isset($this->schemes[$scheme])) {
  56              return $this->schemes[$scheme];
  57          }
  58          if (!isset($allowed_schemes[$scheme])) {
  59              return;
  60          }
  61  
  62          $class = 'HTMLPurifier_URIScheme_' . $scheme;
  63          if (!class_exists($class)) {
  64              return;
  65          }
  66          $this->schemes[$scheme] = new $class();
  67          return $this->schemes[$scheme];
  68      }
  69  
  70      /**
  71       * Registers a custom scheme to the cache, bypassing reflection.
  72       * @param string $scheme Scheme name
  73       * @param HTMLPurifier_URIScheme $scheme_obj
  74       */
  75      public function register($scheme, $scheme_obj)
  76      {
  77          $this->schemes[$scheme] = $scheme_obj;
  78      }
  79  }
  80  
  81  // vim: et sw=4 sts=4