4 * Validates a font family list according to CSS spec
5 * @todo whitelisting allowed fonts would be nice
7 class HTMLPurifier_AttrDef_CSS_FontFamily extends HTMLPurifier_AttrDef
10 public function validate($string, $config, $context) {
11 static $generic_names = array(
19 // assume that no font names contain commas in them
20 $fonts = explode(',', $string);
22 foreach($fonts as $font) {
24 if ($font === '') continue;
25 // match a generic name
26 if (isset($generic_names[$font])) {
27 $final .= $font . ', ';
30 // match a quoted name
31 if ($font[0] === '"' || $font[0] === "'") {
32 $length = strlen($font);
33 if ($length <= 2) continue;
35 if ($font[$length - 1] !== $quote) continue;
36 $font = substr($font, 1, $length - 2);
39 $font = $this->expandCSSEscape($font);
41 // $font is a pure representation of the font name
43 if (ctype_alnum($font) && $font !== '') {
44 // very simple font, allow it in unharmed
45 $final .= $font . ', ';
49 // bugger out on whitespace. form feed (0C) really
50 // shouldn't show up regardless
51 $font = str_replace(array("\n", "\t", "\r", "\x0C"), ' ', $font);
53 // These ugly transforms don't pose a security
54 // risk (as \\ and \" might). We could try to be clever and
55 // use single-quote wrapping when there is a double quote
56 // present, but I have choosen not to implement that.
57 // (warning: this code relies on the selection of quotation
59 $font = str_replace('\\', '\\5C ', $font);
60 $font = str_replace('"', '\\22 ', $font);
62 // complicated font, requires quoting
63 $final .= "\"$font\", "; // note that this will later get turned into "
65 $final = rtrim($final, ', ');
66 if ($final === '') return false;