--- /dev/null
+<?php
+
+/**
+ * Validates a font family list according to CSS spec
+ */
+class HTMLPurifier_AttrDef_CSS_FontFamily extends HTMLPurifier_AttrDef
+{
+
+ protected $mask = null;
+
+ public function __construct()
+ {
+ $this->mask = '_- ';
+ for ($c = 'a'; $c <= 'z'; $c++) {
+ $this->mask .= $c;
+ }
+ for ($c = 'A'; $c <= 'Z'; $c++) {
+ $this->mask .= $c;
+ }
+ for ($c = '0'; $c <= '9'; $c++) {
+ $this->mask .= $c;
+ } // cast-y, but should be fine
+ // special bytes used by UTF-8
+ for ($i = 0x80; $i <= 0xFF; $i++) {
+ // We don't bother excluding invalid bytes in this range,
+ // because the our restriction of well-formed UTF-8 will
+ // prevent these from ever occurring.
+ $this->mask .= chr($i);
+ }
+
+ /*
+ PHP's internal strcspn implementation is
+ O(length of string * length of mask), making it inefficient
+ for large masks. However, it's still faster than
+ preg_match 8)
+ for (p = s1;;) {
+ spanp = s2;
+ do {
+ if (*spanp == c || p == s1_end) {
+ return p - s1;
+ }
+ } while (spanp++ < (s2_end - 1));
+ c = *++p;
+ }
+ */
+ // possible optimization: invert the mask.
+ }
+
+ /**
+ * @param string $string
+ * @param HTMLPurifier_Config $config
+ * @param HTMLPurifier_Context $context
+ * @return bool|string
+ */
+ public function validate($string, $config, $context)
+ {
+ static $generic_names = array(
+ 'serif' => true,
+ 'sans-serif' => true,
+ 'monospace' => true,
+ 'fantasy' => true,
+ 'cursive' => true
+ );
+ $allowed_fonts = $config->get('CSS.AllowedFonts');
+
+ // assume that no font names contain commas in them
+ $fonts = explode(',', $string);
+ $final = '';
+ foreach ($fonts as $font) {
+ $font = trim($font);
+ if ($font === '') {
+ continue;
+ }
+ // match a generic name
+ if (isset($generic_names[$font])) {
+ if ($allowed_fonts === null || isset($allowed_fonts[$font])) {
+ $final .= $font . ', ';
+ }
+ continue;
+ }
+ // match a quoted name
+ if ($font[0] === '"' || $font[0] === "'") {
+ $length = strlen($font);
+ if ($length <= 2) {
+ continue;
+ }
+ $quote = $font[0];
+ if ($font[$length - 1] !== $quote) {
+ continue;
+ }
+ $font = substr($font, 1, $length - 2);
+ }
+
+ $font = $this->expandCSSEscape($font);
+
+ // $font is a pure representation of the font name
+
+ if ($allowed_fonts !== null && !isset($allowed_fonts[$font])) {
+ continue;
+ }
+
+ if (ctype_alnum($font) && $font !== '') {
+ // very simple font, allow it in unharmed
+ $final .= $font . ', ';
+ continue;
+ }
+
+ // bugger out on whitespace. form feed (0C) really
+ // shouldn't show up regardless
+ $font = str_replace(array("\n", "\t", "\r", "\x0C"), ' ', $font);
+
+ // Here, there are various classes of characters which need
+ // to be treated differently:
+ // - Alphanumeric characters are essentially safe. We
+ // handled these above.
+ // - Spaces require quoting, though most parsers will do
+ // the right thing if there aren't any characters that
+ // can be misinterpreted
+ // - Dashes rarely occur, but they fairly unproblematic
+ // for parsing/rendering purposes.
+ // The above characters cover the majority of Western font
+ // names.
+ // - Arbitrary Unicode characters not in ASCII. Because
+ // most parsers give little thought to Unicode, treatment
+ // of these codepoints is basically uniform, even for
+ // punctuation-like codepoints. These characters can
+ // show up in non-Western pages and are supported by most
+ // major browsers, for example: "ＭＳ 明朝" is a
+ // legitimate font-name
+ // <http://ja.wikipedia.org/wiki/MS_明朝>. See
+ // the CSS3 spec for more examples:
+ // <http://www.w3.org/TR/2011/WD-css3-fonts-20110324/localizedfamilynames.png>
+ // You can see live samples of these on the Internet:
+ // <http://www.google.co.jp/search?q=font-family+ＭＳ+明朝|ゴシック>
+ // However, most of these fonts have ASCII equivalents:
+ // for example, 'MS Mincho', and it's considered
+ // professional to use ASCII font names instead of
+ // Unicode font names. Thanks Takeshi Terada for
+ // providing this information.
+ // The following characters, to my knowledge, have not been
+ // used to name font names.
+ // - Single quote. While theoretically you might find a
+ // font name that has a single quote in its name (serving
+ // as an apostrophe, e.g. Dave's Scribble), I haven't
+ // been able to find any actual examples of this.
+ // Internet Explorer's cssText translation (which I
+ // believe is invoked by innerHTML) normalizes any
+ // quoting to single quotes, and fails to escape single
+ // quotes. (Note that this is not IE's behavior for all
+ // CSS properties, just some sort of special casing for
+ // font-family). So a single quote *cannot* be used
+ // safely in the font-family context if there will be an
+ // innerHTML/cssText translation. Note that Firefox 3.x
+ // does this too.
+ // - Double quote. In IE, these get normalized to
+ // single-quotes, no matter what the encoding. (Fun
+ // fact, in IE8, the 'content' CSS property gained
+ // support, where they special cased to preserve encoded
+ // double quotes, but still translate unadorned double
+ // quotes into single quotes.) So, because their
+ // fixpoint behavior is identical to single quotes, they
+ // cannot be allowed either. Firefox 3.x displays
+ // single-quote style behavior.
+ // - Backslashes are reduced by one (so \\ -> \) every
+ // iteration, so they cannot be used safely. This shows
+ // up in IE7, IE8 and FF3
+ // - Semicolons, commas and backticks are handled properly.
+ // - The rest of the ASCII punctuation is handled properly.
+ // We haven't checked what browsers do to unadorned
+ // versions, but this is not important as long as the
+ // browser doesn't /remove/ surrounding quotes (as IE does
+ // for HTML).
+ //
+ // With these results in hand, we conclude that there are
+ // various levels of safety:
+ // - Paranoid: alphanumeric, spaces and dashes(?)
+ // - International: Paranoid + non-ASCII Unicode
+ // - Edgy: Everything except quotes, backslashes
+ // - NoJS: Standards compliance, e.g. sod IE. Note that
+ // with some judicious character escaping (since certain
+ // types of escaping doesn't work) this is theoretically
+ // OK as long as innerHTML/cssText is not called.
+ // We believe that international is a reasonable default
+ // (that we will implement now), and once we do more
+ // extensive research, we may feel comfortable with dropping
+ // it down to edgy.
+
+ // Edgy: alphanumeric, spaces, dashes, underscores and Unicode. Use of
+ // str(c)spn assumes that the string was already well formed
+ // Unicode (which of course it is).
+ if (strspn($font, $this->mask) !== strlen($font)) {
+ continue;
+ }
+
+ // Historical:
+ // In the absence of innerHTML/cssText, these ugly
+ // transforms don't pose a security risk (as \\ and \"
+ // might--these escapes are not supported by most browsers).
+ // We could try to be clever and use single-quote wrapping
+ // when there is a double quote present, but I have choosen
+ // not to implement that. (NOTE: you can reduce the amount
+ // of escapes by one depending on what quoting style you use)
+ // $font = str_replace('\\', '\\5C ', $font);
+ // $font = str_replace('"', '\\22 ', $font);
+ // $font = str_replace("'", '\\27 ', $font);
+
+ // font possibly with spaces, requires quoting
+ $final .= "'$font', ";
+ }
+ $final = rtrim($final, ', ');
+ if ($final === '') {
+ return false;
+ }
+ return $final;
+ }
+
+}
+
+// vim: et sw=4 sts=4
projects / yaffs-website / blobdiff