--- /dev/null
+<?php
+
+// why is this a top level function? Because PHP 5.2.0 doesn't seem to
+// understand how to interpret this filter if it's a static method.
+// It's all really silly, but if we go this route it might be reasonable
+// to coalesce all of these methods into one.
+function htmlpurifier_filter_extractstyleblocks_muteerrorhandler()
+{
+}
+
+/**
+ * This filter extracts <style> blocks from input HTML, cleans them up
+ * using CSSTidy, and then places them in $purifier->context->get('StyleBlocks')
+ * so they can be used elsewhere in the document.
+ *
+ * @note
+ * See tests/HTMLPurifier/Filter/ExtractStyleBlocksTest.php for
+ * sample usage.
+ *
+ * @note
+ * This filter can also be used on stylesheets not included in the
+ * document--something purists would probably prefer. Just directly
+ * call HTMLPurifier_Filter_ExtractStyleBlocks->cleanCSS()
+ */
+class HTMLPurifier_Filter_ExtractStyleBlocks extends HTMLPurifier_Filter
+{
+ /**
+ * @type string
+ */
+ public $name = 'ExtractStyleBlocks';
+
+ /**
+ * @type array
+ */
+ private $_styleMatches = array();
+
+ /**
+ * @type csstidy
+ */
+ private $_tidy;
+
+ /**
+ * @type HTMLPurifier_AttrDef_HTML_ID
+ */
+ private $_id_attrdef;
+
+ /**
+ * @type HTMLPurifier_AttrDef_CSS_Ident
+ */
+ private $_class_attrdef;
+
+ /**
+ * @type HTMLPurifier_AttrDef_Enum
+ */
+ private $_enum_attrdef;
+
+ public function __construct()
+ {
+ $this->_tidy = new csstidy();
+ $this->_tidy->set_cfg('lowercase_s', false);
+ $this->_id_attrdef = new HTMLPurifier_AttrDef_HTML_ID(true);
+ $this->_class_attrdef = new HTMLPurifier_AttrDef_CSS_Ident();
+ $this->_enum_attrdef = new HTMLPurifier_AttrDef_Enum(
+ array(
+ 'first-child',
+ 'link',
+ 'visited',
+ 'active',
+ 'hover',
+ 'focus'
+ )
+ );
+ }
+
+ /**
+ * Save the contents of CSS blocks to style matches
+ * @param array $matches preg_replace style $matches array
+ */
+ protected function styleCallback($matches)
+ {
+ $this->_styleMatches[] = $matches[1];
+ }
+
+ /**
+ * Removes inline <style> tags from HTML, saves them for later use
+ * @param string $html
+ * @param HTMLPurifier_Config $config
+ * @param HTMLPurifier_Context $context
+ * @return string
+ * @todo Extend to indicate non-text/css style blocks
+ */
+ public function preFilter($html, $config, $context)
+ {
+ $tidy = $config->get('Filter.ExtractStyleBlocks.TidyImpl');
+ if ($tidy !== null) {
+ $this->_tidy = $tidy;
+ }
+ // NB: this must be NON-greedy because if we have
+ // <style>foo</style> <style>bar</style>
+ // we must not grab foo</style> <style>bar
+ $html = preg_replace_callback('#<style(?:\s.*)?>(.*)<\/style>#isU', array($this, 'styleCallback'), $html);
+ $style_blocks = $this->_styleMatches;
+ $this->_styleMatches = array(); // reset
+ $context->register('StyleBlocks', $style_blocks); // $context must not be reused
+ if ($this->_tidy) {
+ foreach ($style_blocks as &$style) {
+ $style = $this->cleanCSS($style, $config, $context);
+ }
+ }
+ return $html;
+ }
+
+ /**
+ * Takes CSS (the stuff found in <style>) and cleans it.
+ * @warning Requires CSSTidy <http://csstidy.sourceforge.net/>
+ * @param string $css CSS styling to clean
+ * @param HTMLPurifier_Config $config
+ * @param HTMLPurifier_Context $context
+ * @throws HTMLPurifier_Exception
+ * @return string Cleaned CSS
+ */
+ public function cleanCSS($css, $config, $context)
+ {
+ // prepare scope
+ $scope = $config->get('Filter.ExtractStyleBlocks.Scope');
+ if ($scope !== null) {
+ $scopes = array_map('trim', explode(',', $scope));
+ } else {
+ $scopes = array();
+ }
+ // remove comments from CSS
+ $css = trim($css);
+ if (strncmp('<!--', $css, 4) === 0) {
+ $css = substr($css, 4);
+ }
+ if (strlen($css) > 3 && substr($css, -3) == '-->') {
+ $css = substr($css, 0, -3);
+ }
+ $css = trim($css);
+ set_error_handler('htmlpurifier_filter_extractstyleblocks_muteerrorhandler');
+ $this->_tidy->parse($css);
+ restore_error_handler();
+ $css_definition = $config->getDefinition('CSS');
+ $html_definition = $config->getDefinition('HTML');
+ $new_css = array();
+ foreach ($this->_tidy->css as $k => $decls) {
+ // $decls are all CSS declarations inside an @ selector
+ $new_decls = array();
+ foreach ($decls as $selector => $style) {
+ $selector = trim($selector);
+ if ($selector === '') {
+ continue;
+ } // should not happen
+ // Parse the selector
+ // Here is the relevant part of the CSS grammar:
+ //
+ // ruleset
+ // : selector [ ',' S* selector ]* '{' ...
+ // selector
+ // : simple_selector [ combinator selector | S+ [ combinator? selector ]? ]?
+ // combinator
+ // : '+' S*
+ // : '>' S*
+ // simple_selector
+ // : element_name [ HASH | class | attrib | pseudo ]*
+ // | [ HASH | class | attrib | pseudo ]+
+ // element_name
+ // : IDENT | '*'
+ // ;
+ // class
+ // : '.' IDENT
+ // ;
+ // attrib
+ // : '[' S* IDENT S* [ [ '=' | INCLUDES | DASHMATCH ] S*
+ // [ IDENT | STRING ] S* ]? ']'
+ // ;
+ // pseudo
+ // : ':' [ IDENT | FUNCTION S* [IDENT S*]? ')' ]
+ // ;
+ //
+ // For reference, here are the relevant tokens:
+ //
+ // HASH #{name}
+ // IDENT {ident}
+ // INCLUDES ==
+ // DASHMATCH |=
+ // STRING {string}
+ // FUNCTION {ident}\(
+ //
+ // And the lexical scanner tokens
+ //
+ // name {nmchar}+
+ // nmchar [_a-z0-9-]|{nonascii}|{escape}
+ // nonascii [\240-\377]
+ // escape {unicode}|\\[^\r\n\f0-9a-f]
+ // unicode \\{h}}{1,6}(\r\n|[ \t\r\n\f])?
+ // ident -?{nmstart}{nmchar*}
+ // nmstart [_a-z]|{nonascii}|{escape}
+ // string {string1}|{string2}
+ // string1 \"([^\n\r\f\\"]|\\{nl}|{escape})*\"
+ // string2 \'([^\n\r\f\\"]|\\{nl}|{escape})*\'
+ //
+ // We'll implement a subset (in order to reduce attack
+ // surface); in particular:
+ //
+ // - No Unicode support
+ // - No escapes support
+ // - No string support (by proxy no attrib support)
+ // - element_name is matched against allowed
+ // elements (some people might find this
+ // annoying...)
+ // - Pseudo-elements one of :first-child, :link,
+ // :visited, :active, :hover, :focus
+
+ // handle ruleset
+ $selectors = array_map('trim', explode(',', $selector));
+ $new_selectors = array();
+ foreach ($selectors as $sel) {
+ // split on +, > and spaces
+ $basic_selectors = preg_split('/\s*([+> ])\s*/', $sel, -1, PREG_SPLIT_DELIM_CAPTURE);
+ // even indices are chunks, odd indices are
+ // delimiters
+ $nsel = null;
+ $delim = null; // guaranteed to be non-null after
+ // two loop iterations
+ for ($i = 0, $c = count($basic_selectors); $i < $c; $i++) {
+ $x = $basic_selectors[$i];
+ if ($i % 2) {
+ // delimiter
+ if ($x === ' ') {
+ $delim = ' ';
+ } else {
+ $delim = ' ' . $x . ' ';
+ }
+ } else {
+ // simple selector
+ $components = preg_split('/([#.:])/', $x, -1, PREG_SPLIT_DELIM_CAPTURE);
+ $sdelim = null;
+ $nx = null;
+ for ($j = 0, $cc = count($components); $j < $cc; $j++) {
+ $y = $components[$j];
+ if ($j === 0) {
+ if ($y === '*' || isset($html_definition->info[$y = strtolower($y)])) {
+ $nx = $y;
+ } else {
+ // $nx stays null; this matters
+ // if we don't manage to find
+ // any valid selector content,
+ // in which case we ignore the
+ // outer $delim
+ }
+ } elseif ($j % 2) {
+ // set delimiter
+ $sdelim = $y;
+ } else {
+ $attrdef = null;
+ if ($sdelim === '#') {
+ $attrdef = $this->_id_attrdef;
+ } elseif ($sdelim === '.') {
+ $attrdef = $this->_class_attrdef;
+ } elseif ($sdelim === ':') {
+ $attrdef = $this->_enum_attrdef;
+ } else {
+ throw new HTMLPurifier_Exception('broken invariant sdelim and preg_split');
+ }
+ $r = $attrdef->validate($y, $config, $context);
+ if ($r !== false) {
+ if ($r !== true) {
+ $y = $r;
+ }
+ if ($nx === null) {
+ $nx = '';
+ }
+ $nx .= $sdelim . $y;
+ }
+ }
+ }
+ if ($nx !== null) {
+ if ($nsel === null) {
+ $nsel = $nx;
+ } else {
+ $nsel .= $delim . $nx;
+ }
+ } else {
+ // delimiters to the left of invalid
+ // basic selector ignored
+ }
+ }
+ }
+ if ($nsel !== null) {
+ if (!empty($scopes)) {
+ foreach ($scopes as $s) {
+ $new_selectors[] = "$s $nsel";
+ }
+ } else {
+ $new_selectors[] = $nsel;
+ }
+ }
+ }
+ if (empty($new_selectors)) {
+ continue;
+ }
+ $selector = implode(', ', $new_selectors);
+ foreach ($style as $name => $value) {
+ if (!isset($css_definition->info[$name])) {
+ unset($style[$name]);
+ continue;
+ }
+ $def = $css_definition->info[$name];
+ $ret = $def->validate($value, $config, $context);
+ if ($ret === false) {
+ unset($style[$name]);
+ } else {
+ $style[$name] = $ret;
+ }
+ }
+ $new_decls[$selector] = $style;
+ }
+ $new_css[$k] = $new_decls;
+ }
+ // remove stuff that shouldn't be used, could be reenabled
+ // after security risks are analyzed
+ $this->_tidy->css = $new_css;
+ $this->_tidy->import = array();
+ $this->_tidy->charset = null;
+ $this->_tidy->namespace = null;
+ $css = $this->_tidy->print->plain();
+ // we are going to escape any special characters <>& to ensure
+ // that no funny business occurs (i.e. </style> in a font-family prop).
+ if ($config->get('Filter.ExtractStyleBlocks.Escaping')) {
+ $css = str_replace(
+ array('<', '>', '&'),
+ array('\3C ', '\3E ', '\26 '),
+ $css
+ );
+ }
+ return $css;
+ }
+}
+
+// vim: et sw=4 sts=4
projects / yaffs-website / blobdiff