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   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