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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      public function validate($string, $config, $context) {
  11  
  12          $string = trim($string);
  13          if (!$string) return false;
  14  
  15          $subtags = explode('-', $string);
  16          $num_subtags = count($subtags);
  17  
  18          if ($num_subtags == 0) return false; // sanity check
  19  
  20          // process primary subtag : $subtags[0]
  21          $length = strlen($subtags[0]);
  22          switch ($length) {
  23              case 0:
  24                  return false;
  25              case 1:
  26                  if (! ($subtags[0] == 'x' || $subtags[0] == 'i') ) {
  27                      return false;
  28                  }
  29                  break;
  30              case 2:
  31              case 3:
  32                  if (! ctype_alpha($subtags[0]) ) {
  33                      return false;
  34                  } elseif (! ctype_lower($subtags[0]) ) {
  35                      $subtags[0] = strtolower($subtags[0]);
  36                  }
  37                  break;
  38              default:
  39                  return false;
  40          }
  41  
  42          $new_string = $subtags[0];
  43          if ($num_subtags == 1) return $new_string;
  44  
  45          // process second subtag : $subtags[1]
  46          $length = strlen($subtags[1]);
  47          if ($length == 0 || ($length == 1 && $subtags[1] != 'x') || $length > 8 || !ctype_alnum($subtags[1])) {
  48              return $new_string;
  49          }
  50          if (!ctype_lower($subtags[1])) $subtags[1] = strtolower($subtags[1]);
  51  
  52          $new_string .= '-' . $subtags[1];
  53          if ($num_subtags == 2) return $new_string;
  54  
  55          // process all other subtags, index 2 and up
  56          for ($i = 2; $i < $num_subtags; $i++) {
  57              $length = strlen($subtags[$i]);
  58              if ($length == 0 || $length > 8 || !ctype_alnum($subtags[$i])) {
  59                  return $new_string;
  60              }
  61              if (!ctype_lower($subtags[$i])) {
  62                  $subtags[$i] = strtolower($subtags[$i]);
  63              }
  64              $new_string .= '-' . $subtags[$i];
  65          }
  66  
  67          return $new_string;
  68  
  69      }
  70  
  71  }
  72  
  73  // vim: et sw=4 sts=4