library/HTMLPurifier/AttrDef/CSS/FontFamily.php

   1 <?php
   2
   3 /**
   4  * Validates a font family list according to CSS spec
   5  * @todo whitelisting allowed fonts would be nice
   6  */
   7 class HTMLPurifier_AttrDef_CSS_FontFamily extends HTMLPurifier_AttrDef
   8 {
   9
  10     public function validate($string, $config, $context) {
  11         static $generic_names = array(
  12             'serif' => true,
  13             'sans-serif' => true,
  14             'monospace' => true,
  15             'fantasy' => true,
  16             'cursive' => true
  17         );
  18
  19         // assume that no font names contain commas in them
  20         $fonts = explode(',', $string);
  21         $final = '';
  22         $non_sgml = HTMLPurifier_Encoder::getNonSgmlCharacters();
  23         foreach($fonts as $font) {
  24             $font = trim($font);
  25             if ($font === '') continue;
  26             // match a generic name
  27             if (isset($generic_names[$font])) {
  28                 $final .= $font . ', ';
  29                 continue;
  30             }
  31             // match a quoted name
  32             if ($font[0] === '"' || $font[0] === "'") {
  33                 $length = strlen($font);
  34                 if ($length <= 2) continue;
  35                 $quote = $font[0];
  36                 if ($font[$length - 1] !== $quote) continue;
  37                 $font = substr($font, 1, $length - 2);
  38
  39                 $new_font = '';
  40                 for ($i = 0, $c = strlen($font); $i < $c; $i++) {
  41                     if ($font[$i] === '\\') {
  42                         $i++;
  43                         if ($i >= $c) {
  44                             $new_font .= '\\';
  45                             break;
  46                         }
  47                         if (ctype_xdigit($font[$i])) {
  48                             $code = $font[$i];
  49                             for ($a = 1, $i++; $i < $c && $a < 6; $i++, $a++) {
  50                                 if (!ctype_xdigit($font[$i])) break;
  51                                 $code .= $font[$i];
  52                             }
  53                             $char = HTMLPurifier_Encoder::unichr(hexdec($code));
  54                             if (isset($non_sgml[$char])) continue;
  55                             $new_font .= $char;
  56                             if ($i < $c && trim($font[$i]) !== '') $i--;
  57                             continue;
  58                         }
  59                         if ($font[$i] === "\n") continue;
  60                     }
  61                     $new_font .= $font[$i];
  62                 }
  63
  64                 $font = $new_font;
  65             }
  66             // $font is a pure representation of the font name
  67
  68             if (ctype_alnum($font) && $font !== '') {
  69                 // very simple font, allow it in unharmed
  70                 $final .= $font . ', ';
  71                 continue;
  72             }
  73
  74             // complicated font, requires quoting
  75
  76             // armor single quotes and new lines
  77             $font = str_replace("\\", "\\\\", $font);
  78             $font = str_replace("'", "\\'", $font);
  79             $final .= "'$font', ";
  80         }
  81         $final = rtrim($final, ', ');
  82         if ($final === '') return false;
  83         return $final;
  84     }
  85
  86 }
  87