library/HTMLPurifier/URIFilter/Munge.php

   1 <?php
   2
   3 class HTMLPurifier_URIFilter_Munge extends HTMLPurifier_URIFilter
   4 {
   5     /**
   6      * @type string
   7      */
   8     public $name = 'Munge';
   9
  10     /**
  11      * @type bool
  12      */
  13     public $post = true;
  14
  15     /**
  16      * @type string
  17      */
  18     private $target;
  19
  20     /**
  21      * @type HTMLPurifier_URIParser
  22      */
  23     private $parser;
  24
  25     /**
  26      * @type bool
  27      */
  28     private $doEmbed;
  29
  30     /**
  31      * @type string
  32      */
  33     private $secretKey;
  34
  35     /**
  36      * @type array
  37      */
  38     protected $replace = array();
  39
  40     /**
  41      * @param HTMLPurifier_Config $config
  42      * @return bool
  43      */
  44     public function prepare($config)
  45     {
  46         $this->target = $config->get('URI.' . $this->name);
  47         $this->parser = new HTMLPurifier_URIParser();
  48         $this->doEmbed = $config->get('URI.MungeResources');
  49         $this->secretKey = $config->get('URI.MungeSecretKey');
  50         if ($this->secretKey && !function_exists('hash_hmac')) {
  51             throw new Exception("Cannot use %URI.MungeSecretKey without hash_hmac support.");
  52         }
  53         return true;
  54     }
  55
  56     /**
  57      * @param HTMLPurifier_URI $uri
  58      * @param HTMLPurifier_Config $config
  59      * @param HTMLPurifier_Context $context
  60      * @return bool
  61      */
  62     public function filter(&$uri, $config, $context)
  63     {
  64         if ($context->get('EmbeddedURI', true) && !$this->doEmbed) {
  65             return true;
  66         }
  67
  68         $scheme_obj = $uri->getSchemeObj($config, $context);
  69         if (!$scheme_obj) {
  70             return true;
  71         } // ignore unknown schemes, maybe another postfilter did it
  72         if (!$scheme_obj->browsable) {
  73             return true;
  74         } // ignore non-browseable schemes, since we can't munge those in a reasonable way
  75         if ($uri->isBenign($config, $context)) {
  76             return true;
  77         } // don't redirect if a benign URL
  78
  79         $this->makeReplace($uri, $config, $context);
  80         $this->replace = array_map('rawurlencode', $this->replace);
  81
  82         $new_uri = strtr($this->target, $this->replace);
  83         $new_uri = $this->parser->parse($new_uri);
  84         // don't redirect if the target host is the same as the
  85         // starting host
  86         if ($uri->host === $new_uri->host) {
  87             return true;
  88         }
  89         $uri = $new_uri; // overwrite
  90         return true;
  91     }
  92
  93     /**
  94      * @param HTMLPurifier_URI $uri
  95      * @param HTMLPurifier_Config $config
  96      * @param HTMLPurifier_Context $context
  97      */
  98     protected function makeReplace($uri, $config, $context)
  99     {
 100         $string = $uri->toString();
 101         // always available
 102         $this->replace['%s'] = $string;
 103         $this->replace['%r'] = $context->get('EmbeddedURI', true);
 104         $token = $context->get('CurrentToken', true);
 105         $this->replace['%n'] = $token ? $token->name : null;
 106         $this->replace['%m'] = $context->get('CurrentAttr', true);
 107         $this->replace['%p'] = $context->get('CurrentCSSProperty', true);
 108         // not always available
 109         if ($this->secretKey) {
 110             $this->replace['%t'] = hash_hmac("sha256", $string, $this->secretKey);
 111         }
 112     }
 113 }
 114
 115 // vim: et sw=4 sts=4