library/HTMLPurifier/AttrDef/Lang.php

   1 <?php
   2
   3 /**
   4  * Validates the HTML attribute lang, effectively a language code.
   5  * @note Built according to RFC 3066, which obsoleted RFC 1766
   6  */
   7 class HTMLPurifier_AttrDef_Lang extends HTMLPurifier_AttrDef
   8 {
   9
  10     /**
  11      * @param string $string
  12      * @param HTMLPurifier_Config $config
  13      * @param HTMLPurifier_Context $context
  14      * @return bool|string
  15      */
  16     public function validate($string, $config, $context)
  17     {
  18         $string = trim($string);
  19         if (!$string) {
  20             return false;
  21         }
  22
  23         $subtags = explode('-', $string);
  24         $num_subtags = count($subtags);
  25
  26         if ($num_subtags == 0) { // sanity check
  27             return false;
  28         }
  29
  30         // process primary subtag : $subtags[0]
  31         $length = strlen($subtags[0]);
  32         switch ($length) {
  33             case 0:
  34                 return false;
  35             case 1:
  36                 if (!($subtags[0] == 'x' || $subtags[0] == 'i')) {
  37                     return false;
  38                 }
  39                 break;
  40             case 2:
  41             case 3:
  42                 if (!ctype_alpha($subtags[0])) {
  43                     return false;
  44                 } elseif (!ctype_lower($subtags[0])) {
  45                     $subtags[0] = strtolower($subtags[0]);
  46                 }
  47                 break;
  48             default:
  49                 return false;
  50         }
  51
  52         $new_string = $subtags[0];
  53         if ($num_subtags == 1) {
  54             return $new_string;
  55         }
  56
  57         // process second subtag : $subtags[1]
  58         $length = strlen($subtags[1]);
  59         if ($length == 0 || ($length == 1 && $subtags[1] != 'x') || $length > 8 || !ctype_alnum($subtags[1])) {
  60             return $new_string;
  61         }
  62         if (!ctype_lower($subtags[1])) {
  63             $subtags[1] = strtolower($subtags[1]);
  64         }
  65
  66         $new_string .= '-' . $subtags[1];
  67         if ($num_subtags == 2) {
  68             return $new_string;
  69         }
  70
  71         // process all other subtags, index 2 and up
  72         for ($i = 2; $i < $num_subtags; $i++) {
  73             $length = strlen($subtags[$i]);
  74             if ($length == 0 || $length > 8 || !ctype_alnum($subtags[$i])) {
  75                 return $new_string;
  76             }
  77             if (!ctype_lower($subtags[$i])) {
  78                 $subtags[$i] = strtolower($subtags[$i]);
  79             }
  80             $new_string .= '-' . $subtags[$i];
  81         }
  82         return $new_string;
  83     }
  84 }
  85
  86 // vim: et sw=4 sts=4