342 lines
13 KiB
PHP
342 lines
13 KiB
PHP
<?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
|