WordPress/wp-includes/kses.php
dmsnell 9c25b9d9b8 KSES: Fix tests and detection of HTML Bogus Comment spans.
In [58418] a test was added without the `test_` prefix in its function
name, and because of that, it wasn't run in the test suite.
The prefix has been added to ensure that it runs.

In the original patch, due to a logical bug, a recursive loop to
transform the inside contents of the bogus comments was never run
more than once. This has been fixed.

This patch also includes one more case where `kses` wasn't
properly detecting the bogus comment state, and adds a test case
to cover this. It limits itself to some but not all constructions
of invalid markup declaration so that it doesn't conflict with
existing behaviors around those and other kinds of invalid comments.

Props ellatrix, dmsnell.
See #61009.
Follow-up to [58418].

Built from https://develop.svn.wordpress.org/trunk@58424


git-svn-id: http://core.svn.wordpress.org/trunk@57873 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2024-06-17 12:04:12 +00:00

2780 lines
73 KiB
PHP

<?php
/**
* kses 0.2.2 - HTML/XHTML filter that only allows some elements and attributes
* Copyright (C) 2002, 2003, 2005 Ulf Harnhammar
*
* This program is free software and open source software; you can redistribute
* it and/or modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the License,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
* http://www.gnu.org/licenses/gpl.html
*
* [kses strips evil scripts!]
*
* Added wp_ prefix to avoid conflicts with existing kses users
*
* @version 0.2.2
* @copyright (C) 2002, 2003, 2005
* @author Ulf Harnhammar <http://advogato.org/person/metaur/>
*
* @package External
* @subpackage KSES
*/
/**
* Specifies the default allowable HTML tags.
*
* Using `CUSTOM_TAGS` is not recommended and should be considered deprecated. The
* {@see 'wp_kses_allowed_html'} filter is more powerful and supplies context.
*
* When using this constant, make sure to set all of these globals to arrays:
*
* - `$allowedposttags`
* - `$allowedtags`
* - `$allowedentitynames`
* - `$allowedxmlentitynames`
*
* @see wp_kses_allowed_html()
* @since 1.2.0
*
* @var array[]|false Array of default allowable HTML tags, or false to use the defaults.
*/
if ( ! defined( 'CUSTOM_TAGS' ) ) {
define( 'CUSTOM_TAGS', false );
}
// Ensure that these variables are added to the global namespace
// (e.g. if using namespaces / autoload in the current PHP environment).
global $allowedposttags, $allowedtags, $allowedentitynames, $allowedxmlentitynames;
if ( ! CUSTOM_TAGS ) {
/**
* KSES global for default allowable HTML tags.
*
* Can be overridden with the `CUSTOM_TAGS` constant.
*
* @var array[] $allowedposttags Array of default allowable HTML tags.
* @since 2.0.0
*/
$allowedposttags = array(
'address' => array(),
'a' => array(
'href' => true,
'rel' => true,
'rev' => true,
'name' => true,
'target' => true,
'download' => array(
'valueless' => 'y',
),
),
'abbr' => array(),
'acronym' => array(),
'area' => array(
'alt' => true,
'coords' => true,
'href' => true,
'nohref' => true,
'shape' => true,
'target' => true,
),
'article' => array(
'align' => true,
),
'aside' => array(
'align' => true,
),
'audio' => array(
'autoplay' => true,
'controls' => true,
'loop' => true,
'muted' => true,
'preload' => true,
'src' => true,
),
'b' => array(),
'bdo' => array(),
'big' => array(),
'blockquote' => array(
'cite' => true,
),
'br' => array(),
'button' => array(
'disabled' => true,
'name' => true,
'type' => true,
'value' => true,
),
'caption' => array(
'align' => true,
),
'cite' => array(),
'code' => array(),
'col' => array(
'align' => true,
'char' => true,
'charoff' => true,
'span' => true,
'valign' => true,
'width' => true,
),
'colgroup' => array(
'align' => true,
'char' => true,
'charoff' => true,
'span' => true,
'valign' => true,
'width' => true,
),
'del' => array(
'datetime' => true,
),
'dd' => array(),
'dfn' => array(),
'details' => array(
'align' => true,
'open' => true,
),
'div' => array(
'align' => true,
),
'dl' => array(),
'dt' => array(),
'em' => array(),
'fieldset' => array(),
'figure' => array(
'align' => true,
),
'figcaption' => array(
'align' => true,
),
'font' => array(
'color' => true,
'face' => true,
'size' => true,
),
'footer' => array(
'align' => true,
),
'h1' => array(
'align' => true,
),
'h2' => array(
'align' => true,
),
'h3' => array(
'align' => true,
),
'h4' => array(
'align' => true,
),
'h5' => array(
'align' => true,
),
'h6' => array(
'align' => true,
),
'header' => array(
'align' => true,
),
'hgroup' => array(
'align' => true,
),
'hr' => array(
'align' => true,
'noshade' => true,
'size' => true,
'width' => true,
),
'i' => array(),
'img' => array(
'alt' => true,
'align' => true,
'border' => true,
'height' => true,
'hspace' => true,
'loading' => true,
'longdesc' => true,
'vspace' => true,
'src' => true,
'usemap' => true,
'width' => true,
),
'ins' => array(
'datetime' => true,
'cite' => true,
),
'kbd' => array(),
'label' => array(
'for' => true,
),
'legend' => array(
'align' => true,
),
'li' => array(
'align' => true,
'value' => true,
),
'main' => array(
'align' => true,
),
'map' => array(
'name' => true,
),
'mark' => array(),
'menu' => array(
'type' => true,
),
'nav' => array(
'align' => true,
),
'object' => array(
'data' => array(
'required' => true,
'value_callback' => '_wp_kses_allow_pdf_objects',
),
'type' => array(
'required' => true,
'values' => array( 'application/pdf' ),
),
),
'p' => array(
'align' => true,
),
'pre' => array(
'width' => true,
),
'q' => array(
'cite' => true,
),
'rb' => array(),
'rp' => array(),
'rt' => array(),
'rtc' => array(),
'ruby' => array(),
's' => array(),
'samp' => array(),
'span' => array(
'align' => true,
),
'section' => array(
'align' => true,
),
'small' => array(),
'strike' => array(),
'strong' => array(),
'sub' => array(),
'summary' => array(
'align' => true,
),
'sup' => array(),
'table' => array(
'align' => true,
'bgcolor' => true,
'border' => true,
'cellpadding' => true,
'cellspacing' => true,
'rules' => true,
'summary' => true,
'width' => true,
),
'tbody' => array(
'align' => true,
'char' => true,
'charoff' => true,
'valign' => true,
),
'td' => array(
'abbr' => true,
'align' => true,
'axis' => true,
'bgcolor' => true,
'char' => true,
'charoff' => true,
'colspan' => true,
'headers' => true,
'height' => true,
'nowrap' => true,
'rowspan' => true,
'scope' => true,
'valign' => true,
'width' => true,
),
'textarea' => array(
'cols' => true,
'rows' => true,
'disabled' => true,
'name' => true,
'readonly' => true,
),
'tfoot' => array(
'align' => true,
'char' => true,
'charoff' => true,
'valign' => true,
),
'th' => array(
'abbr' => true,
'align' => true,
'axis' => true,
'bgcolor' => true,
'char' => true,
'charoff' => true,
'colspan' => true,
'headers' => true,
'height' => true,
'nowrap' => true,
'rowspan' => true,
'scope' => true,
'valign' => true,
'width' => true,
),
'thead' => array(
'align' => true,
'char' => true,
'charoff' => true,
'valign' => true,
),
'title' => array(),
'tr' => array(
'align' => true,
'bgcolor' => true,
'char' => true,
'charoff' => true,
'valign' => true,
),
'track' => array(
'default' => true,
'kind' => true,
'label' => true,
'src' => true,
'srclang' => true,
),
'tt' => array(),
'u' => array(),
'ul' => array(
'type' => true,
),
'ol' => array(
'start' => true,
'type' => true,
'reversed' => true,
),
'var' => array(),
'video' => array(
'autoplay' => true,
'controls' => true,
'height' => true,
'loop' => true,
'muted' => true,
'playsinline' => true,
'poster' => true,
'preload' => true,
'src' => true,
'width' => true,
),
);
/**
* @var array[] $allowedtags Array of KSES allowed HTML elements.
* @since 1.0.0
*/
$allowedtags = array(
'a' => array(
'href' => true,
'title' => true,
),
'abbr' => array(
'title' => true,
),
'acronym' => array(
'title' => true,
),
'b' => array(),
'blockquote' => array(
'cite' => true,
),
'cite' => array(),
'code' => array(),
'del' => array(
'datetime' => true,
),
'em' => array(),
'i' => array(),
'q' => array(
'cite' => true,
),
's' => array(),
'strike' => array(),
'strong' => array(),
);
/**
* @var string[] $allowedentitynames Array of KSES allowed HTML entity names.
* @since 1.0.0
*/
$allowedentitynames = array(
'nbsp',
'iexcl',
'cent',
'pound',
'curren',
'yen',
'brvbar',
'sect',
'uml',
'copy',
'ordf',
'laquo',
'not',
'shy',
'reg',
'macr',
'deg',
'plusmn',
'acute',
'micro',
'para',
'middot',
'cedil',
'ordm',
'raquo',
'iquest',
'Agrave',
'Aacute',
'Acirc',
'Atilde',
'Auml',
'Aring',
'AElig',
'Ccedil',
'Egrave',
'Eacute',
'Ecirc',
'Euml',
'Igrave',
'Iacute',
'Icirc',
'Iuml',
'ETH',
'Ntilde',
'Ograve',
'Oacute',
'Ocirc',
'Otilde',
'Ouml',
'times',
'Oslash',
'Ugrave',
'Uacute',
'Ucirc',
'Uuml',
'Yacute',
'THORN',
'szlig',
'agrave',
'aacute',
'acirc',
'atilde',
'auml',
'aring',
'aelig',
'ccedil',
'egrave',
'eacute',
'ecirc',
'euml',
'igrave',
'iacute',
'icirc',
'iuml',
'eth',
'ntilde',
'ograve',
'oacute',
'ocirc',
'otilde',
'ouml',
'divide',
'oslash',
'ugrave',
'uacute',
'ucirc',
'uuml',
'yacute',
'thorn',
'yuml',
'quot',
'amp',
'lt',
'gt',
'apos',
'OElig',
'oelig',
'Scaron',
'scaron',
'Yuml',
'circ',
'tilde',
'ensp',
'emsp',
'thinsp',
'zwnj',
'zwj',
'lrm',
'rlm',
'ndash',
'mdash',
'lsquo',
'rsquo',
'sbquo',
'ldquo',
'rdquo',
'bdquo',
'dagger',
'Dagger',
'permil',
'lsaquo',
'rsaquo',
'euro',
'fnof',
'Alpha',
'Beta',
'Gamma',
'Delta',
'Epsilon',
'Zeta',
'Eta',
'Theta',
'Iota',
'Kappa',
'Lambda',
'Mu',
'Nu',
'Xi',
'Omicron',
'Pi',
'Rho',
'Sigma',
'Tau',
'Upsilon',
'Phi',
'Chi',
'Psi',
'Omega',
'alpha',
'beta',
'gamma',
'delta',
'epsilon',
'zeta',
'eta',
'theta',
'iota',
'kappa',
'lambda',
'mu',
'nu',
'xi',
'omicron',
'pi',
'rho',
'sigmaf',
'sigma',
'tau',
'upsilon',
'phi',
'chi',
'psi',
'omega',
'thetasym',
'upsih',
'piv',
'bull',
'hellip',
'prime',
'Prime',
'oline',
'frasl',
'weierp',
'image',
'real',
'trade',
'alefsym',
'larr',
'uarr',
'rarr',
'darr',
'harr',
'crarr',
'lArr',
'uArr',
'rArr',
'dArr',
'hArr',
'forall',
'part',
'exist',
'empty',
'nabla',
'isin',
'notin',
'ni',
'prod',
'sum',
'minus',
'lowast',
'radic',
'prop',
'infin',
'ang',
'and',
'or',
'cap',
'cup',
'int',
'sim',
'cong',
'asymp',
'ne',
'equiv',
'le',
'ge',
'sub',
'sup',
'nsub',
'sube',
'supe',
'oplus',
'otimes',
'perp',
'sdot',
'lceil',
'rceil',
'lfloor',
'rfloor',
'lang',
'rang',
'loz',
'spades',
'clubs',
'hearts',
'diams',
'sup1',
'sup2',
'sup3',
'frac14',
'frac12',
'frac34',
'there4',
);
/**
* @var string[] $allowedxmlentitynames Array of KSES allowed XML entity names.
* @since 5.5.0
*/
$allowedxmlentitynames = array(
'amp',
'lt',
'gt',
'apos',
'quot',
);
$allowedposttags = array_map( '_wp_add_global_attributes', $allowedposttags );
} else {
$required_kses_globals = array(
'allowedposttags',
'allowedtags',
'allowedentitynames',
'allowedxmlentitynames',
);
$missing_kses_globals = array();
foreach ( $required_kses_globals as $global_name ) {
if ( ! isset( $GLOBALS[ $global_name ] ) || ! is_array( $GLOBALS[ $global_name ] ) ) {
$missing_kses_globals[] = '<code>$' . $global_name . '</code>';
}
}
if ( $missing_kses_globals ) {
_doing_it_wrong(
'wp_kses_allowed_html',
sprintf(
/* translators: 1: CUSTOM_TAGS, 2: Global variable names. */
__( 'When using the %1$s constant, make sure to set these globals to an array: %2$s.' ),
'<code>CUSTOM_TAGS</code>',
implode( ', ', $missing_kses_globals )
),
'6.2.0'
);
}
$allowedtags = wp_kses_array_lc( $allowedtags );
$allowedposttags = wp_kses_array_lc( $allowedposttags );
}
/**
* Filters text content and strips out disallowed HTML.
*
* This function makes sure that only the allowed HTML element names, attribute
* names, attribute values, and HTML entities will occur in the given text string.
*
* This function expects unslashed data.
*
* @see wp_kses_post() for specifically filtering post content and fields.
* @see wp_allowed_protocols() for the default allowed protocols in link URLs.
*
* @since 1.0.0
*
* @param string $content Text content to filter.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Optional. Array of allowed URL protocols.
* Defaults to the result of wp_allowed_protocols().
* @return string Filtered content containing only the allowed HTML.
*/
function wp_kses( $content, $allowed_html, $allowed_protocols = array() ) {
if ( empty( $allowed_protocols ) ) {
$allowed_protocols = wp_allowed_protocols();
}
$content = wp_kses_no_null( $content, array( 'slash_zero' => 'keep' ) );
$content = wp_kses_normalize_entities( $content );
$content = wp_kses_hook( $content, $allowed_html, $allowed_protocols );
return wp_kses_split( $content, $allowed_html, $allowed_protocols );
}
/**
* Filters one HTML attribute and ensures its value is allowed.
*
* This function can escape data in some situations where `wp_kses()` must strip the whole attribute.
*
* @since 4.2.3
*
* @param string $attr The 'whole' attribute, including name and value.
* @param string $element The HTML element name to which the attribute belongs.
* @return string Filtered attribute.
*/
function wp_kses_one_attr( $attr, $element ) {
$uris = wp_kses_uri_attributes();
$allowed_html = wp_kses_allowed_html( 'post' );
$allowed_protocols = wp_allowed_protocols();
$attr = wp_kses_no_null( $attr, array( 'slash_zero' => 'keep' ) );
// Preserve leading and trailing whitespace.
$matches = array();
preg_match( '/^\s*/', $attr, $matches );
$lead = $matches[0];
preg_match( '/\s*$/', $attr, $matches );
$trail = $matches[0];
if ( empty( $trail ) ) {
$attr = substr( $attr, strlen( $lead ) );
} else {
$attr = substr( $attr, strlen( $lead ), -strlen( $trail ) );
}
// Parse attribute name and value from input.
$split = preg_split( '/\s*=\s*/', $attr, 2 );
$name = $split[0];
if ( count( $split ) === 2 ) {
$value = $split[1];
/*
* Remove quotes surrounding $value.
* Also guarantee correct quoting in $attr for this one attribute.
*/
if ( '' === $value ) {
$quote = '';
} else {
$quote = $value[0];
}
if ( '"' === $quote || "'" === $quote ) {
if ( ! str_ends_with( $value, $quote ) ) {
return '';
}
$value = substr( $value, 1, -1 );
} else {
$quote = '"';
}
// Sanitize quotes, angle braces, and entities.
$value = esc_attr( $value );
// Sanitize URI values.
if ( in_array( strtolower( $name ), $uris, true ) ) {
$value = wp_kses_bad_protocol( $value, $allowed_protocols );
}
$attr = "$name=$quote$value$quote";
$vless = 'n';
} else {
$value = '';
$vless = 'y';
}
// Sanitize attribute by name.
wp_kses_attr_check( $name, $value, $attr, $vless, $element, $allowed_html );
// Restore whitespace.
return $lead . $attr . $trail;
}
/**
* Returns an array of allowed HTML tags and attributes for a given context.
*
* @since 3.5.0
* @since 5.0.1 `form` removed as allowable HTML tag.
*
* @global array $allowedposttags
* @global array $allowedtags
* @global array $allowedentitynames
*
* @param string|array $context The context for which to retrieve tags. Allowed values are 'post',
* 'strip', 'data', 'entities', or the name of a field filter such as
* 'pre_user_description', or an array of allowed HTML elements and attributes.
* @return array Array of allowed HTML tags and their allowed attributes.
*/
function wp_kses_allowed_html( $context = '' ) {
global $allowedposttags, $allowedtags, $allowedentitynames;
if ( is_array( $context ) ) {
// When `$context` is an array it's actually an array of allowed HTML elements and attributes.
$html = $context;
$context = 'explicit';
/**
* Filters the HTML tags that are allowed for a given context.
*
* HTML tags and attribute names are case-insensitive in HTML but must be
* added to the KSES allow list in lowercase. An item added to the allow list
* in upper or mixed case will not recognized as permitted by KSES.
*
* @since 3.5.0
*
* @param array[] $html Allowed HTML tags.
* @param string $context Context name.
*/
return apply_filters( 'wp_kses_allowed_html', $html, $context );
}
switch ( $context ) {
case 'post':
/** This filter is documented in wp-includes/kses.php */
$tags = apply_filters( 'wp_kses_allowed_html', $allowedposttags, $context );
// 5.0.1 removed the `<form>` tag, allow it if a filter is allowing it's sub-elements `<input>` or `<select>`.
if ( ! CUSTOM_TAGS && ! isset( $tags['form'] ) && ( isset( $tags['input'] ) || isset( $tags['select'] ) ) ) {
$tags = $allowedposttags;
$tags['form'] = array(
'action' => true,
'accept' => true,
'accept-charset' => true,
'enctype' => true,
'method' => true,
'name' => true,
'target' => true,
);
/** This filter is documented in wp-includes/kses.php */
$tags = apply_filters( 'wp_kses_allowed_html', $tags, $context );
}
return $tags;
case 'user_description':
case 'pre_user_description':
$tags = $allowedtags;
$tags['a']['rel'] = true;
/** This filter is documented in wp-includes/kses.php */
return apply_filters( 'wp_kses_allowed_html', $tags, $context );
case 'strip':
/** This filter is documented in wp-includes/kses.php */
return apply_filters( 'wp_kses_allowed_html', array(), $context );
case 'entities':
/** This filter is documented in wp-includes/kses.php */
return apply_filters( 'wp_kses_allowed_html', $allowedentitynames, $context );
case 'data':
default:
/** This filter is documented in wp-includes/kses.php */
return apply_filters( 'wp_kses_allowed_html', $allowedtags, $context );
}
}
/**
* You add any KSES hooks here.
*
* There is currently only one KSES WordPress hook, {@see 'pre_kses'}, and it is called here.
* All parameters are passed to the hooks and expected to receive a string.
*
* @since 1.0.0
*
* @param string $content Content to filter through KSES.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return string Filtered content through {@see 'pre_kses'} hook.
*/
function wp_kses_hook( $content, $allowed_html, $allowed_protocols ) {
/**
* Filters content to be run through KSES.
*
* @since 2.3.0
*
* @param string $content Content to filter through KSES.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Array of allowed URL protocols.
*/
return apply_filters( 'pre_kses', $content, $allowed_html, $allowed_protocols );
}
/**
* Returns the version number of KSES.
*
* @since 1.0.0
*
* @return string KSES version number.
*/
function wp_kses_version() {
return '0.2.2';
}
/**
* Searches for HTML tags, no matter how malformed.
*
* It also matches stray `>` characters.
*
* @since 1.0.0
* @since 6.6.0 Recognize additional forms of invalid HTML which convert into comments.
*
* @global array[]|string $pass_allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'.
* @global string[] $pass_allowed_protocols Array of allowed URL protocols.
*
* @param string $content Content to filter.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return string Content with fixed HTML tags
*/
function wp_kses_split( $content, $allowed_html, $allowed_protocols ) {
global $pass_allowed_html, $pass_allowed_protocols;
$pass_allowed_html = $allowed_html;
$pass_allowed_protocols = $allowed_protocols;
$token_pattern = <<<REGEX
~
( # Detect comments of various flavors before attempting to find tags.
(<!--.*?(-->|$)) # - Normative HTML comments.
|
</[^a-zA-Z][^>]*> # - Closing tags with invalid tag names.
|
<![^>]*> # - Invalid markup declaration nodes. Not all invalid nodes
# are matched so as to avoid breaking legacy behaviors.
)
|
(<[^>]*(>|$)|>) # Tag-like spans of text.
~x
REGEX;
return preg_replace_callback( $token_pattern, '_wp_kses_split_callback', $content );
}
/**
* Returns an array of HTML attribute names whose value contains a URL.
*
* This function returns a list of all HTML attributes that must contain
* a URL according to the HTML specification.
*
* This list includes URI attributes both allowed and disallowed by KSES.
*
* @link https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes
*
* @since 5.0.1
*
* @return string[] HTML attribute names whose value contains a URL.
*/
function wp_kses_uri_attributes() {
$uri_attributes = array(
'action',
'archive',
'background',
'cite',
'classid',
'codebase',
'data',
'formaction',
'href',
'icon',
'longdesc',
'manifest',
'poster',
'profile',
'src',
'usemap',
'xmlns',
);
/**
* Filters the list of attributes that are required to contain a URL.
*
* Use this filter to add any `data-` attributes that are required to be
* validated as a URL.
*
* @since 5.0.1
*
* @param string[] $uri_attributes HTML attribute names whose value contains a URL.
*/
$uri_attributes = apply_filters( 'wp_kses_uri_attributes', $uri_attributes );
return $uri_attributes;
}
/**
* Callback for `wp_kses_split()`.
*
* @since 3.1.0
* @access private
* @ignore
*
* @global array[]|string $pass_allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'.
* @global string[] $pass_allowed_protocols Array of allowed URL protocols.
*
* @param array $matches preg_replace regexp matches
* @return string
*/
function _wp_kses_split_callback( $matches ) {
global $pass_allowed_html, $pass_allowed_protocols;
return wp_kses_split2( $matches[0], $pass_allowed_html, $pass_allowed_protocols );
}
/**
* Callback for `wp_kses_split()` for fixing malformed HTML tags.
*
* This function does a lot of work. It rejects some very malformed things like
* `<:::>`. It returns an empty string, if the element isn't allowed (look ma, no
* `strip_tags()`!). Otherwise it splits the tag into an element and an attribute
* list.
*
* After the tag is split into an element and an attribute list, it is run
* through another filter which will remove illegal attributes and once that is
* completed, will be returned.
*
* @access private
* @ignore
* @since 1.0.0
* @since 6.6.0 Recognize additional forms of invalid HTML which convert into comments.
*
* @param string $content Content to filter.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Array of allowed URL protocols.
*
* @return string Fixed HTML element
*/
function wp_kses_split2( $content, $allowed_html, $allowed_protocols ) {
$content = wp_kses_stripslashes( $content );
/*
* The regex pattern used to split HTML into chunks attempts
* to split on HTML token boundaries. This function should
* thus receive chunks that _either_ start with meaningful
* syntax tokens, like a tag `<div>` or a comment `<!-- ... -->`.
*
* If the first character of the `$content` chunk _isn't_ one
* of these syntax elements, which always starts with `<`, then
* the match had to be for the final alternation of `>`. In such
* case, it's probably standing on its own and could be encoded
* with a character reference to remove ambiguity.
*
* In other words, if this chunk isn't from a match of a syntax
* token, it's just a plaintext greater-than (`>`) sign.
*/
if ( ! str_starts_with( $content, '<' ) ) {
return '&gt;';
}
/*
* When certain invalid syntax constructs appear, the HTML parser
* shifts into what's called the "bogus comment state." This is a
* plaintext state that consumes everything until the nearest `>`
* and then transforms the entire span into an HTML comment.
*
* Preserve these comments and do not treat them like tags.
*
* @see https://html.spec.whatwg.org/#bogus-comment-state
*/
if ( 1 === preg_match( '~^(?:</[^a-zA-Z][^>]*>|<![a-z][^>]*>)$~', $content ) ) {
/**
* Since the pattern matches `</…>` and also `<!…>`, this will
* preserve the type of the cleaned-up token in the output.
*/
$opener = $content[1];
$content = substr( $content, 2, -1 );
do {
$prev = $content;
$content = wp_kses( $content, $allowed_html, $allowed_protocols );
} while ( $prev !== $content );
// Recombine the modified inner content with the original token structure.
return "<{$opener}{$content}>";
}
/*
* Normative HTML comments should be handled separately as their
* parsing rules differ from those for tags and text nodes.
*/
if ( str_starts_with( $content, '<!--' ) ) {
$content = str_replace( array( '<!--', '-->' ), '', $content );
while ( ( $newstring = wp_kses( $content, $allowed_html, $allowed_protocols ) ) !== $content ) {
$content = $newstring;
}
if ( '' === $content ) {
return '';
}
// Prevent multiple dashes in comments.
$content = preg_replace( '/--+/', '-', $content );
// Prevent three dashes closing a comment.
$content = preg_replace( '/-$/', '', $content );
return "<!--{$content}-->";
}
// It's seriously malformed.
if ( ! preg_match( '%^<\s*(/\s*)?([a-zA-Z0-9-]+)([^>]*)>?$%', $content, $matches ) ) {
return '';
}
$slash = trim( $matches[1] );
$elem = $matches[2];
$attrlist = $matches[3];
if ( ! is_array( $allowed_html ) ) {
$allowed_html = wp_kses_allowed_html( $allowed_html );
}
// They are using a not allowed HTML element.
if ( ! isset( $allowed_html[ strtolower( $elem ) ] ) ) {
return '';
}
// No attributes are allowed for closing elements.
if ( '' !== $slash ) {
return "</$elem>";
}
return wp_kses_attr( $elem, $attrlist, $allowed_html, $allowed_protocols );
}
/**
* Removes all attributes, if none are allowed for this element.
*
* If some are allowed it calls `wp_kses_hair()` to split them further, and then
* it builds up new HTML code from the data that `wp_kses_hair()` returns. It also
* removes `<` and `>` characters, if there are any left. One more thing it does
* is to check if the tag has a closing XHTML slash, and if it does, it puts one
* in the returned code as well.
*
* An array of allowed values can be defined for attributes. If the attribute value
* doesn't fall into the list, the attribute will be removed from the tag.
*
* Attributes can be marked as required. If a required attribute is not present,
* KSES will remove all attributes from the tag. As KSES doesn't match opening and
* closing tags, it's not possible to safely remove the tag itself, the safest
* fallback is to strip all attributes from the tag, instead.
*
* @since 1.0.0
* @since 5.9.0 Added support for an array of allowed values for attributes.
* Added support for required attributes.
*
* @param string $element HTML element/tag.
* @param string $attr HTML attributes from HTML element to closing HTML element tag.
* @param array[]|string $allowed_html An array of allowed HTML elements and attributes,
* or a context name such as 'post'. See wp_kses_allowed_html()
* for the list of accepted context names.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return string Sanitized HTML element.
*/
function wp_kses_attr( $element, $attr, $allowed_html, $allowed_protocols ) {
if ( ! is_array( $allowed_html ) ) {
$allowed_html = wp_kses_allowed_html( $allowed_html );
}
// Is there a closing XHTML slash at the end of the attributes?
$xhtml_slash = '';
if ( preg_match( '%\s*/\s*$%', $attr ) ) {
$xhtml_slash = ' /';
}
// Are any attributes allowed at all for this element?
$element_low = strtolower( $element );
if ( empty( $allowed_html[ $element_low ] ) || true === $allowed_html[ $element_low ] ) {
return "<$element$xhtml_slash>";
}
// Split it.
$attrarr = wp_kses_hair( $attr, $allowed_protocols );
// Check if there are attributes that are required.
$required_attrs = array_filter(
$allowed_html[ $element_low ],
static function ( $required_attr_limits ) {
return isset( $required_attr_limits['required'] ) && true === $required_attr_limits['required'];
}
);
/*
* If a required attribute check fails, we can return nothing for a self-closing tag,
* but for a non-self-closing tag the best option is to return the element with attributes,
* as KSES doesn't handle matching the relevant closing tag.
*/
$stripped_tag = '';
if ( empty( $xhtml_slash ) ) {
$stripped_tag = "<$element>";
}
// Go through $attrarr, and save the allowed attributes for this element in $attr2.
$attr2 = '';
foreach ( $attrarr as $arreach ) {
// Check if this attribute is required.
$required = isset( $required_attrs[ strtolower( $arreach['name'] ) ] );
if ( wp_kses_attr_check( $arreach['name'], $arreach['value'], $arreach['whole'], $arreach['vless'], $element, $allowed_html ) ) {
$attr2 .= ' ' . $arreach['whole'];
// If this was a required attribute, we can mark it as found.
if ( $required ) {
unset( $required_attrs[ strtolower( $arreach['name'] ) ] );
}
} elseif ( $required ) {
// This attribute was required, but didn't pass the check. The entire tag is not allowed.
return $stripped_tag;
}
}
// If some required attributes weren't set, the entire tag is not allowed.
if ( ! empty( $required_attrs ) ) {
return $stripped_tag;
}
// Remove any "<" or ">" characters.
$attr2 = preg_replace( '/[<>]/', '', $attr2 );
return "<$element$attr2$xhtml_slash>";
}
/**
* Determines whether an attribute is allowed.
*
* @since 4.2.3
* @since 5.0.0 Added support for `data-*` wildcard attributes.
*
* @param string $name The attribute name. Passed by reference. Returns empty string when not allowed.
* @param string $value The attribute value. Passed by reference. Returns a filtered value.
* @param string $whole The `name=value` input. Passed by reference. Returns filtered input.
* @param string $vless Whether the attribute is valueless. Use 'y' or 'n'.
* @param string $element The name of the element to which this attribute belongs.
* @param array $allowed_html The full list of allowed elements and attributes.
* @return bool Whether or not the attribute is allowed.
*/
function wp_kses_attr_check( &$name, &$value, &$whole, $vless, $element, $allowed_html ) {
$name_low = strtolower( $name );
$element_low = strtolower( $element );
if ( ! isset( $allowed_html[ $element_low ] ) ) {
$name = '';
$value = '';
$whole = '';
return false;
}
$allowed_attr = $allowed_html[ $element_low ];
if ( ! isset( $allowed_attr[ $name_low ] ) || '' === $allowed_attr[ $name_low ] ) {
/*
* Allow `data-*` attributes.
*
* When specifying `$allowed_html`, the attribute name should be set as
* `data-*` (not to be mixed with the HTML 4.0 `data` attribute, see
* https://www.w3.org/TR/html40/struct/objects.html#adef-data).
*
* Note: the attribute name should only contain `A-Za-z0-9_-` chars.
*/
if ( str_starts_with( $name_low, 'data-' ) && ! empty( $allowed_attr['data-*'] )
&& preg_match( '/^data-[a-z0-9_-]+$/', $name_low, $match )
) {
/*
* Add the whole attribute name to the allowed attributes and set any restrictions
* for the `data-*` attribute values for the current element.
*/
$allowed_attr[ $match[0] ] = $allowed_attr['data-*'];
} else {
$name = '';
$value = '';
$whole = '';
return false;
}
}
if ( 'style' === $name_low ) {
$new_value = safecss_filter_attr( $value );
if ( empty( $new_value ) ) {
$name = '';
$value = '';
$whole = '';
return false;
}
$whole = str_replace( $value, $new_value, $whole );
$value = $new_value;
}
if ( is_array( $allowed_attr[ $name_low ] ) ) {
// There are some checks.
foreach ( $allowed_attr[ $name_low ] as $currkey => $currval ) {
if ( ! wp_kses_check_attr_val( $value, $vless, $currkey, $currval ) ) {
$name = '';
$value = '';
$whole = '';
return false;
}
}
}
return true;
}
/**
* Builds an attribute list from string containing attributes.
*
* This function does a lot of work. It parses an attribute list into an array
* with attribute data, and tries to do the right thing even if it gets weird
* input. It will add quotes around attribute values that don't have any quotes
* or apostrophes around them, to make it easier to produce HTML code that will
* conform to W3C's HTML specification. It will also remove bad URL protocols
* from attribute values. It also reduces duplicate attributes by using the
* attribute defined first (`foo='bar' foo='baz'` will result in `foo='bar'`).
*
* @since 1.0.0
*
* @param string $attr Attribute list from HTML element to closing HTML element tag.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return array[] Array of attribute information after parsing.
*/
function wp_kses_hair( $attr, $allowed_protocols ) {
$attrarr = array();
$mode = 0;
$attrname = '';
$uris = wp_kses_uri_attributes();
// Loop through the whole attribute list.
while ( strlen( $attr ) !== 0 ) {
$working = 0; // Was the last operation successful?
switch ( $mode ) {
case 0:
if ( preg_match( '/^([_a-zA-Z][-_a-zA-Z0-9:.]*)/', $attr, $match ) ) {
$attrname = $match[1];
$working = 1;
$mode = 1;
$attr = preg_replace( '/^[_a-zA-Z][-_a-zA-Z0-9:.]*/', '', $attr );
}
break;
case 1:
if ( preg_match( '/^\s*=\s*/', $attr ) ) { // Equals sign.
$working = 1;
$mode = 2;
$attr = preg_replace( '/^\s*=\s*/', '', $attr );
break;
}
if ( preg_match( '/^\s+/', $attr ) ) { // Valueless.
$working = 1;
$mode = 0;
if ( false === array_key_exists( $attrname, $attrarr ) ) {
$attrarr[ $attrname ] = array(
'name' => $attrname,
'value' => '',
'whole' => $attrname,
'vless' => 'y',
);
}
$attr = preg_replace( '/^\s+/', '', $attr );
}
break;
case 2:
if ( preg_match( '%^"([^"]*)"(\s+|/?$)%', $attr, $match ) ) {
// "value"
$thisval = $match[1];
if ( in_array( strtolower( $attrname ), $uris, true ) ) {
$thisval = wp_kses_bad_protocol( $thisval, $allowed_protocols );
}
if ( false === array_key_exists( $attrname, $attrarr ) ) {
$attrarr[ $attrname ] = array(
'name' => $attrname,
'value' => $thisval,
'whole' => "$attrname=\"$thisval\"",
'vless' => 'n',
);
}
$working = 1;
$mode = 0;
$attr = preg_replace( '/^"[^"]*"(\s+|$)/', '', $attr );
break;
}
if ( preg_match( "%^'([^']*)'(\s+|/?$)%", $attr, $match ) ) {
// 'value'
$thisval = $match[1];
if ( in_array( strtolower( $attrname ), $uris, true ) ) {
$thisval = wp_kses_bad_protocol( $thisval, $allowed_protocols );
}
if ( false === array_key_exists( $attrname, $attrarr ) ) {
$attrarr[ $attrname ] = array(
'name' => $attrname,
'value' => $thisval,
'whole' => "$attrname='$thisval'",
'vless' => 'n',
);
}
$working = 1;
$mode = 0;
$attr = preg_replace( "/^'[^']*'(\s+|$)/", '', $attr );
break;
}
if ( preg_match( "%^([^\s\"']+)(\s+|/?$)%", $attr, $match ) ) {
// value
$thisval = $match[1];
if ( in_array( strtolower( $attrname ), $uris, true ) ) {
$thisval = wp_kses_bad_protocol( $thisval, $allowed_protocols );
}
if ( false === array_key_exists( $attrname, $attrarr ) ) {
$attrarr[ $attrname ] = array(
'name' => $attrname,
'value' => $thisval,
'whole' => "$attrname=\"$thisval\"",
'vless' => 'n',
);
}
// We add quotes to conform to W3C's HTML spec.
$working = 1;
$mode = 0;
$attr = preg_replace( "%^[^\s\"']+(\s+|$)%", '', $attr );
}
break;
} // End switch.
if ( 0 === $working ) { // Not well-formed, remove and try again.
$attr = wp_kses_html_error( $attr );
$mode = 0;
}
} // End while.
if ( 1 === $mode && false === array_key_exists( $attrname, $attrarr ) ) {
/*
* Special case, for when the attribute list ends with a valueless
* attribute like "selected".
*/
$attrarr[ $attrname ] = array(
'name' => $attrname,
'value' => '',
'whole' => $attrname,
'vless' => 'y',
);
}
return $attrarr;
}
/**
* Finds all attributes of an HTML element.
*
* Does not modify input. May return "evil" output.
*
* Based on `wp_kses_split2()` and `wp_kses_attr()`.
*
* @since 4.2.3
*
* @param string $element HTML element.
* @return array|false List of attributes found in the element. Returns false on failure.
*/
function wp_kses_attr_parse( $element ) {
$valid = preg_match( '%^(<\s*)(/\s*)?([a-zA-Z0-9]+\s*)([^>]*)(>?)$%', $element, $matches );
if ( 1 !== $valid ) {
return false;
}
$begin = $matches[1];
$slash = $matches[2];
$elname = $matches[3];
$attr = $matches[4];
$end = $matches[5];
if ( '' !== $slash ) {
// Closing elements do not get parsed.
return false;
}
// Is there a closing XHTML slash at the end of the attributes?
if ( 1 === preg_match( '%\s*/\s*$%', $attr, $matches ) ) {
$xhtml_slash = $matches[0];
$attr = substr( $attr, 0, -strlen( $xhtml_slash ) );
} else {
$xhtml_slash = '';
}
// Split it.
$attrarr = wp_kses_hair_parse( $attr );
if ( false === $attrarr ) {
return false;
}
// Make sure all input is returned by adding front and back matter.
array_unshift( $attrarr, $begin . $slash . $elname );
array_push( $attrarr, $xhtml_slash . $end );
return $attrarr;
}
/**
* Builds an attribute list from string containing attributes.
*
* Does not modify input. May return "evil" output.
* In case of unexpected input, returns false instead of stripping things.
*
* Based on `wp_kses_hair()` but does not return a multi-dimensional array.
*
* @since 4.2.3
*
* @param string $attr Attribute list from HTML element to closing HTML element tag.
* @return array|false List of attributes found in $attr. Returns false on failure.
*/
function wp_kses_hair_parse( $attr ) {
if ( '' === $attr ) {
return array();
}
$regex =
'(?:
[_a-zA-Z][-_a-zA-Z0-9:.]* # Attribute name.
|
\[\[?[^\[\]]+\]\]? # Shortcode in the name position implies unfiltered_html.
)
(?: # Attribute value.
\s*=\s* # All values begin with "=".
(?:
"[^"]*" # Double-quoted.
|
\'[^\']*\' # Single-quoted.
|
[^\s"\']+ # Non-quoted.
(?:\s|$) # Must have a space.
)
|
(?:\s|$) # If attribute has no value, space is required.
)
\s* # Trailing space is optional except as mentioned above.
';
/*
* Although it is possible to reduce this procedure to a single regexp,
* we must run that regexp twice to get exactly the expected result.
*
* Note: do NOT remove the `x` modifiers as they are essential for the above regex!
*/
$validation = "/^($regex)+$/x";
$extraction = "/$regex/x";
if ( 1 === preg_match( $validation, $attr ) ) {
preg_match_all( $extraction, $attr, $attrarr );
return $attrarr[0];
} else {
return false;
}
}
/**
* Performs different checks for attribute values.
*
* The currently implemented checks are "maxlen", "minlen", "maxval", "minval",
* and "valueless".
*
* @since 1.0.0
*
* @param string $value Attribute value.
* @param string $vless Whether the attribute is valueless. Use 'y' or 'n'.
* @param string $checkname What $checkvalue is checking for.
* @param mixed $checkvalue What constraint the value should pass.
* @return bool Whether check passes.
*/
function wp_kses_check_attr_val( $value, $vless, $checkname, $checkvalue ) {
$ok = true;
switch ( strtolower( $checkname ) ) {
case 'maxlen':
/*
* The maxlen check makes sure that the attribute value has a length not
* greater than the given value. This can be used to avoid Buffer Overflows
* in WWW clients and various Internet servers.
*/
if ( strlen( $value ) > $checkvalue ) {
$ok = false;
}
break;
case 'minlen':
/*
* The minlen check makes sure that the attribute value has a length not
* smaller than the given value.
*/
if ( strlen( $value ) < $checkvalue ) {
$ok = false;
}
break;
case 'maxval':
/*
* The maxval check does two things: it checks that the attribute value is
* an integer from 0 and up, without an excessive amount of zeroes or
* whitespace (to avoid Buffer Overflows). It also checks that the attribute
* value is not greater than the given value.
* This check can be used to avoid Denial of Service attacks.
*/
if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {
$ok = false;
}
if ( $value > $checkvalue ) {
$ok = false;
}
break;
case 'minval':
/*
* The minval check makes sure that the attribute value is a positive integer,
* and that it is not smaller than the given value.
*/
if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {
$ok = false;
}
if ( $value < $checkvalue ) {
$ok = false;
}
break;
case 'valueless':
/*
* The valueless check makes sure if the attribute has a value
* (like `<a href="blah">`) or not (`<option selected>`). If the given value
* is a "y" or a "Y", the attribute must not have a value.
* If the given value is an "n" or an "N", the attribute must have a value.
*/
if ( strtolower( $checkvalue ) !== $vless ) {
$ok = false;
}
break;
case 'values':
/*
* The values check is used when you want to make sure that the attribute
* has one of the given values.
*/
if ( false === array_search( strtolower( $value ), $checkvalue, true ) ) {
$ok = false;
}
break;
case 'value_callback':
/*
* The value_callback check is used when you want to make sure that the attribute
* value is accepted by the callback function.
*/
if ( ! call_user_func( $checkvalue, $value ) ) {
$ok = false;
}
break;
} // End switch.
return $ok;
}
/**
* Sanitizes a string and removed disallowed URL protocols.
*
* This function removes all non-allowed protocols from the beginning of the
* string. It ignores whitespace and the case of the letters, and it does
* understand HTML entities. It does its work recursively, so it won't be
* fooled by a string like `javascript:javascript:alert(57)`.
*
* @since 1.0.0
*
* @param string $content Content to filter bad protocols from.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return string Filtered content.
*/
function wp_kses_bad_protocol( $content, $allowed_protocols ) {
$content = wp_kses_no_null( $content );
// Short-circuit if the string starts with `https://` or `http://`. Most common cases.
if (
( str_starts_with( $content, 'https://' ) && in_array( 'https', $allowed_protocols, true ) ) ||
( str_starts_with( $content, 'http://' ) && in_array( 'http', $allowed_protocols, true ) )
) {
return $content;
}
$iterations = 0;
do {
$original_content = $content;
$content = wp_kses_bad_protocol_once( $content, $allowed_protocols );
} while ( $original_content !== $content && ++$iterations < 6 );
if ( $original_content !== $content ) {
return '';
}
return $content;
}
/**
* Removes any invalid control characters in a text string.
*
* Also removes any instance of the `\0` string.
*
* @since 1.0.0
*
* @param string $content Content to filter null characters from.
* @param array $options Set 'slash_zero' => 'keep' when '\0' is allowed. Default is 'remove'.
* @return string Filtered content.
*/
function wp_kses_no_null( $content, $options = null ) {
if ( ! isset( $options['slash_zero'] ) ) {
$options = array( 'slash_zero' => 'remove' );
}
$content = preg_replace( '/[\x00-\x08\x0B\x0C\x0E-\x1F]/', '', $content );
if ( 'remove' === $options['slash_zero'] ) {
$content = preg_replace( '/\\\\+0+/', '', $content );
}
return $content;
}
/**
* Strips slashes from in front of quotes.
*
* This function changes the character sequence `\"` to just `"`. It leaves all other
* slashes alone. The quoting from `preg_replace(//e)` requires this.
*
* @since 1.0.0
*
* @param string $content String to strip slashes from.
* @return string Fixed string with quoted slashes.
*/
function wp_kses_stripslashes( $content ) {
return preg_replace( '%\\\\"%', '"', $content );
}
/**
* Converts the keys of an array to lowercase.
*
* @since 1.0.0
*
* @param array $inarray Unfiltered array.
* @return array Fixed array with all lowercase keys.
*/
function wp_kses_array_lc( $inarray ) {
$outarray = array();
foreach ( (array) $inarray as $inkey => $inval ) {
$outkey = strtolower( $inkey );
$outarray[ $outkey ] = array();
foreach ( (array) $inval as $inkey2 => $inval2 ) {
$outkey2 = strtolower( $inkey2 );
$outarray[ $outkey ][ $outkey2 ] = $inval2;
}
}
return $outarray;
}
/**
* Handles parsing errors in `wp_kses_hair()`.
*
* The general plan is to remove everything to and including some whitespace,
* but it deals with quotes and apostrophes as well.
*
* @since 1.0.0
*
* @param string $attr
* @return string
*/
function wp_kses_html_error( $attr ) {
return preg_replace( '/^("[^"]*("|$)|\'[^\']*(\'|$)|\S)*\s*/', '', $attr );
}
/**
* Sanitizes content from bad protocols and other characters.
*
* This function searches for URL protocols at the beginning of the string, while
* handling whitespace and HTML entities.
*
* @since 1.0.0
*
* @param string $content Content to check for bad protocols.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @param int $count Depth of call recursion to this function.
* @return string Sanitized content.
*/
function wp_kses_bad_protocol_once( $content, $allowed_protocols, $count = 1 ) {
$content = preg_replace( '/(&#0*58(?![;0-9])|&#x0*3a(?![;a-f0-9]))/i', '$1;', $content );
$content2 = preg_split( '/:|&#0*58;|&#x0*3a;|&colon;/i', $content, 2 );
if ( isset( $content2[1] ) && ! preg_match( '%/\?%', $content2[0] ) ) {
$content = trim( $content2[1] );
$protocol = wp_kses_bad_protocol_once2( $content2[0], $allowed_protocols );
if ( 'feed:' === $protocol ) {
if ( $count > 2 ) {
return '';
}
$content = wp_kses_bad_protocol_once( $content, $allowed_protocols, ++$count );
if ( empty( $content ) ) {
return $content;
}
}
$content = $protocol . $content;
}
return $content;
}
/**
* Callback for `wp_kses_bad_protocol_once()` regular expression.
*
* This function processes URL protocols, checks to see if they're in the
* list of allowed protocols or not, and returns different data depending
* on the answer.
*
* @access private
* @ignore
* @since 1.0.0
*
* @param string $scheme URI scheme to check against the list of allowed protocols.
* @param string[] $allowed_protocols Array of allowed URL protocols.
* @return string Sanitized content.
*/
function wp_kses_bad_protocol_once2( $scheme, $allowed_protocols ) {
$scheme = wp_kses_decode_entities( $scheme );
$scheme = preg_replace( '/\s/', '', $scheme );
$scheme = wp_kses_no_null( $scheme );
$scheme = strtolower( $scheme );
$allowed = false;
foreach ( (array) $allowed_protocols as $one_protocol ) {
if ( strtolower( $one_protocol ) === $scheme ) {
$allowed = true;
break;
}
}
if ( $allowed ) {
return "$scheme:";
} else {
return '';
}
}
/**
* Converts and fixes HTML entities.
*
* This function normalizes HTML entities. It will convert `AT&T` to the correct
* `AT&amp;T`, `&#00058;` to `&#058;`, `&#XYZZY;` to `&amp;#XYZZY;` and so on.
*
* When `$context` is set to 'xml', HTML entities are converted to their code points. For
* example, `AT&T&hellip;&#XYZZY;` is converted to `AT&amp;T…&amp;#XYZZY;`.
*
* @since 1.0.0
* @since 5.5.0 Added `$context` parameter.
*
* @param string $content Content to normalize entities.
* @param string $context Context for normalization. Can be either 'html' or 'xml'.
* Default 'html'.
* @return string Content with normalized entities.
*/
function wp_kses_normalize_entities( $content, $context = 'html' ) {
// Disarm all entities by converting & to &amp;
$content = str_replace( '&', '&amp;', $content );
// Change back the allowed entities in our list of allowed entities.
if ( 'xml' === $context ) {
$content = preg_replace_callback( '/&amp;([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_xml_named_entities', $content );
} else {
$content = preg_replace_callback( '/&amp;([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_named_entities', $content );
}
$content = preg_replace_callback( '/&amp;#(0*[0-9]{1,7});/', 'wp_kses_normalize_entities2', $content );
$content = preg_replace_callback( '/&amp;#[Xx](0*[0-9A-Fa-f]{1,6});/', 'wp_kses_normalize_entities3', $content );
return $content;
}
/**
* Callback for `wp_kses_normalize_entities()` regular expression.
*
* This function only accepts valid named entity references, which are finite,
* case-sensitive, and highly scrutinized by HTML and XML validators.
*
* @since 3.0.0
*
* @global array $allowedentitynames
*
* @param array $matches preg_replace_callback() matches array.
* @return string Correctly encoded entity.
*/
function wp_kses_named_entities( $matches ) {
global $allowedentitynames;
if ( empty( $matches[1] ) ) {
return '';
}
$i = $matches[1];
return ( ! in_array( $i, $allowedentitynames, true ) ) ? "&amp;$i;" : "&$i;";
}
/**
* Callback for `wp_kses_normalize_entities()` regular expression.
*
* This function only accepts valid named entity references, which are finite,
* case-sensitive, and highly scrutinized by XML validators. HTML named entity
* references are converted to their code points.
*
* @since 5.5.0
*
* @global array $allowedentitynames
* @global array $allowedxmlentitynames
*
* @param array $matches preg_replace_callback() matches array.
* @return string Correctly encoded entity.
*/
function wp_kses_xml_named_entities( $matches ) {
global $allowedentitynames, $allowedxmlentitynames;
if ( empty( $matches[1] ) ) {
return '';
}
$i = $matches[1];
if ( in_array( $i, $allowedxmlentitynames, true ) ) {
return "&$i;";
} elseif ( in_array( $i, $allowedentitynames, true ) ) {
return html_entity_decode( "&$i;", ENT_HTML5 );
}
return "&amp;$i;";
}
/**
* Callback for `wp_kses_normalize_entities()` regular expression.
*
* This function helps `wp_kses_normalize_entities()` to only accept 16-bit
* values and nothing more for `&#number;` entities.
*
* @access private
* @ignore
* @since 1.0.0
*
* @param array $matches `preg_replace_callback()` matches array.
* @return string Correctly encoded entity.
*/
function wp_kses_normalize_entities2( $matches ) {
if ( empty( $matches[1] ) ) {
return '';
}
$i = $matches[1];
if ( valid_unicode( $i ) ) {
$i = str_pad( ltrim( $i, '0' ), 3, '0', STR_PAD_LEFT );
$i = "&#$i;";
} else {
$i = "&amp;#$i;";
}
return $i;
}
/**
* Callback for `wp_kses_normalize_entities()` for regular expression.
*
* This function helps `wp_kses_normalize_entities()` to only accept valid Unicode
* numeric entities in hex form.
*
* @since 2.7.0
* @access private
* @ignore
*
* @param array $matches `preg_replace_callback()` matches array.
* @return string Correctly encoded entity.
*/
function wp_kses_normalize_entities3( $matches ) {
if ( empty( $matches[1] ) ) {
return '';
}
$hexchars = $matches[1];
return ( ! valid_unicode( hexdec( $hexchars ) ) ) ? "&amp;#x$hexchars;" : '&#x' . ltrim( $hexchars, '0' ) . ';';
}
/**
* Determines if a Unicode codepoint is valid.
*
* @since 2.7.0
*
* @param int $i Unicode codepoint.
* @return bool Whether or not the codepoint is a valid Unicode codepoint.
*/
function valid_unicode( $i ) {
$i = (int) $i;
return ( 0x9 === $i || 0xa === $i || 0xd === $i ||
( 0x20 <= $i && $i <= 0xd7ff ) ||
( 0xe000 <= $i && $i <= 0xfffd ) ||
( 0x10000 <= $i && $i <= 0x10ffff )
);
}
/**
* Converts all numeric HTML entities to their named counterparts.
*
* This function decodes numeric HTML entities (`&#65;` and `&#x41;`).
* It doesn't do anything with named entities like `&auml;`, but we don't
* need them in the allowed URL protocols system anyway.
*
* @since 1.0.0
*
* @param string $content Content to change entities.
* @return string Content after decoded entities.
*/
function wp_kses_decode_entities( $content ) {
$content = preg_replace_callback( '/&#([0-9]+);/', '_wp_kses_decode_entities_chr', $content );
$content = preg_replace_callback( '/&#[Xx]([0-9A-Fa-f]+);/', '_wp_kses_decode_entities_chr_hexdec', $content );
return $content;
}
/**
* Regex callback for `wp_kses_decode_entities()`.
*
* @since 2.9.0
* @access private
* @ignore
*
* @param array $matches preg match
* @return string
*/
function _wp_kses_decode_entities_chr( $matches ) {
return chr( $matches[1] );
}
/**
* Regex callback for `wp_kses_decode_entities()`.
*
* @since 2.9.0
* @access private
* @ignore
*
* @param array $matches preg match
* @return string
*/
function _wp_kses_decode_entities_chr_hexdec( $matches ) {
return chr( hexdec( $matches[1] ) );
}
/**
* Sanitize content with allowed HTML KSES rules.
*
* This function expects slashed data.
*
* @since 1.0.0
*
* @param string $data Content to filter, expected to be escaped with slashes.
* @return string Filtered content.
*/
function wp_filter_kses( $data ) {
return addslashes( wp_kses( stripslashes( $data ), current_filter() ) );
}
/**
* Sanitize content with allowed HTML KSES rules.
*
* This function expects unslashed data.
*
* @since 2.9.0
*
* @param string $data Content to filter, expected to not be escaped.
* @return string Filtered content.
*/
function wp_kses_data( $data ) {
return wp_kses( $data, current_filter() );
}
/**
* Sanitizes content for allowed HTML tags for post content.
*
* Post content refers to the page contents of the 'post' type and not `$_POST`
* data from forms.
*
* This function expects slashed data.
*
* @since 2.0.0
*
* @param string $data Post content to filter, expected to be escaped with slashes.
* @return string Filtered post content with allowed HTML tags and attributes intact.
*/
function wp_filter_post_kses( $data ) {
return addslashes( wp_kses( stripslashes( $data ), 'post' ) );
}
/**
* Sanitizes global styles user content removing unsafe rules.
*
* @since 5.9.0
*
* @param string $data Post content to filter.
* @return string Filtered post content with unsafe rules removed.
*/
function wp_filter_global_styles_post( $data ) {
$decoded_data = json_decode( wp_unslash( $data ), true );
$json_decoding_error = json_last_error();
if (
JSON_ERROR_NONE === $json_decoding_error &&
is_array( $decoded_data ) &&
isset( $decoded_data['isGlobalStylesUserThemeJSON'] ) &&
$decoded_data['isGlobalStylesUserThemeJSON']
) {
unset( $decoded_data['isGlobalStylesUserThemeJSON'] );
$data_to_encode = WP_Theme_JSON::remove_insecure_properties( $decoded_data, 'custom' );
$data_to_encode['isGlobalStylesUserThemeJSON'] = true;
return wp_slash( wp_json_encode( $data_to_encode ) );
}
return $data;
}
/**
* Sanitizes content for allowed HTML tags for post content.
*
* Post content refers to the page contents of the 'post' type and not `$_POST`
* data from forms.
*
* This function expects unslashed data.
*
* @since 2.9.0
*
* @param string $data Post content to filter.
* @return string Filtered post content with allowed HTML tags and attributes intact.
*/
function wp_kses_post( $data ) {
return wp_kses( $data, 'post' );
}
/**
* Navigates through an array, object, or scalar, and sanitizes content for
* allowed HTML tags for post content.
*
* @since 4.4.2
*
* @see map_deep()
*
* @param mixed $data The array, object, or scalar value to inspect.
* @return mixed The filtered content.
*/
function wp_kses_post_deep( $data ) {
return map_deep( $data, 'wp_kses_post' );
}
/**
* Strips all HTML from a text string.
*
* This function expects slashed data.
*
* @since 2.1.0
*
* @param string $data Content to strip all HTML from.
* @return string Filtered content without any HTML.
*/
function wp_filter_nohtml_kses( $data ) {
return addslashes( wp_kses( stripslashes( $data ), 'strip' ) );
}
/**
* Adds all KSES input form content filters.
*
* All hooks have default priority. The `wp_filter_kses()` function is added to
* the 'pre_comment_content' and 'title_save_pre' hooks.
*
* The `wp_filter_post_kses()` function is added to the 'content_save_pre',
* 'excerpt_save_pre', and 'content_filtered_save_pre' hooks.
*
* @since 2.0.0
*/
function kses_init_filters() {
// Normal filtering.
add_filter( 'title_save_pre', 'wp_filter_kses' );
// Comment filtering.
if ( current_user_can( 'unfiltered_html' ) ) {
add_filter( 'pre_comment_content', 'wp_filter_post_kses' );
} else {
add_filter( 'pre_comment_content', 'wp_filter_kses' );
}
// Global Styles filtering: Global Styles filters should be executed before normal post_kses HTML filters.
add_filter( 'content_save_pre', 'wp_filter_global_styles_post', 9 );
add_filter( 'content_filtered_save_pre', 'wp_filter_global_styles_post', 9 );
// Post filtering.
add_filter( 'content_save_pre', 'wp_filter_post_kses' );
add_filter( 'excerpt_save_pre', 'wp_filter_post_kses' );
add_filter( 'content_filtered_save_pre', 'wp_filter_post_kses' );
}
/**
* Removes all KSES input form content filters.
*
* A quick procedural method to removing all of the filters that KSES uses for
* content in WordPress Loop.
*
* Does not remove the `kses_init()` function from {@see 'init'} hook (priority is
* default). Also does not remove `kses_init()` function from {@see 'set_current_user'}
* hook (priority is also default).
*
* @since 2.0.6
*/
function kses_remove_filters() {
// Normal filtering.
remove_filter( 'title_save_pre', 'wp_filter_kses' );
// Comment filtering.
remove_filter( 'pre_comment_content', 'wp_filter_post_kses' );
remove_filter( 'pre_comment_content', 'wp_filter_kses' );
// Global Styles filtering.
remove_filter( 'content_save_pre', 'wp_filter_global_styles_post', 9 );
remove_filter( 'content_filtered_save_pre', 'wp_filter_global_styles_post', 9 );
// Post filtering.
remove_filter( 'content_save_pre', 'wp_filter_post_kses' );
remove_filter( 'excerpt_save_pre', 'wp_filter_post_kses' );
remove_filter( 'content_filtered_save_pre', 'wp_filter_post_kses' );
}
/**
* Sets up most of the KSES filters for input form content.
*
* First removes all of the KSES filters in case the current user does not need
* to have KSES filter the content. If the user does not have `unfiltered_html`
* capability, then KSES filters are added.
*
* @since 2.0.0
*/
function kses_init() {
kses_remove_filters();
if ( ! current_user_can( 'unfiltered_html' ) ) {
kses_init_filters();
}
}
/**
* Filters an inline style attribute and removes disallowed rules.
*
* @since 2.8.1
* @since 4.4.0 Added support for `min-height`, `max-height`, `min-width`, and `max-width`.
* @since 4.6.0 Added support for `list-style-type`.
* @since 5.0.0 Added support for `background-image`.
* @since 5.1.0 Added support for `text-transform`.
* @since 5.2.0 Added support for `background-position` and `grid-template-columns`.
* @since 5.3.0 Added support for `grid`, `flex` and `column` layout properties.
* Extended `background-*` support for individual properties.
* @since 5.3.1 Added support for gradient backgrounds.
* @since 5.7.1 Added support for `object-position`.
* @since 5.8.0 Added support for `calc()` and `var()` values.
* @since 6.1.0 Added support for `min()`, `max()`, `minmax()`, `clamp()`,
* nested `var()` values, and assigning values to CSS variables.
* Added support for `object-fit`, `gap`, `column-gap`, `row-gap`, and `flex-wrap`.
* Extended `margin-*` and `padding-*` support for logical properties.
* @since 6.2.0 Added support for `aspect-ratio`, `position`, `top`, `right`, `bottom`, `left`,
* and `z-index` CSS properties.
* @since 6.3.0 Extended support for `filter` to accept a URL and added support for repeat().
* Added support for `box-shadow`.
* @since 6.4.0 Added support for `writing-mode`.
* @since 6.5.0 Added support for `background-repeat`.
* @since 6.6.0 Added support for `grid-column`, `grid-row`, and `container-type`.
*
* @param string $css A string of CSS rules.
* @param string $deprecated Not used.
* @return string Filtered string of CSS rules.
*/
function safecss_filter_attr( $css, $deprecated = '' ) {
if ( ! empty( $deprecated ) ) {
_deprecated_argument( __FUNCTION__, '2.8.1' ); // Never implemented.
}
$css = wp_kses_no_null( $css );
$css = str_replace( array( "\n", "\r", "\t" ), '', $css );
$allowed_protocols = wp_allowed_protocols();
$css_array = explode( ';', trim( $css ) );
/**
* Filters the list of allowed CSS attributes.
*
* @since 2.8.1
*
* @param string[] $attr Array of allowed CSS attributes.
*/
$allowed_attr = apply_filters(
'safe_style_css',
array(
'background',
'background-color',
'background-image',
'background-position',
'background-repeat',
'background-size',
'background-attachment',
'background-blend-mode',
'border',
'border-radius',
'border-width',
'border-color',
'border-style',
'border-right',
'border-right-color',
'border-right-style',
'border-right-width',
'border-bottom',
'border-bottom-color',
'border-bottom-left-radius',
'border-bottom-right-radius',
'border-bottom-style',
'border-bottom-width',
'border-bottom-right-radius',
'border-bottom-left-radius',
'border-left',
'border-left-color',
'border-left-style',
'border-left-width',
'border-top',
'border-top-color',
'border-top-left-radius',
'border-top-right-radius',
'border-top-style',
'border-top-width',
'border-top-left-radius',
'border-top-right-radius',
'border-spacing',
'border-collapse',
'caption-side',
'columns',
'column-count',
'column-fill',
'column-gap',
'column-rule',
'column-span',
'column-width',
'color',
'filter',
'font',
'font-family',
'font-size',
'font-style',
'font-variant',
'font-weight',
'letter-spacing',
'line-height',
'text-align',
'text-decoration',
'text-indent',
'text-transform',
'height',
'min-height',
'max-height',
'width',
'min-width',
'max-width',
'margin',
'margin-right',
'margin-bottom',
'margin-left',
'margin-top',
'margin-block-start',
'margin-block-end',
'margin-inline-start',
'margin-inline-end',
'padding',
'padding-right',
'padding-bottom',
'padding-left',
'padding-top',
'padding-block-start',
'padding-block-end',
'padding-inline-start',
'padding-inline-end',
'flex',
'flex-basis',
'flex-direction',
'flex-flow',
'flex-grow',
'flex-shrink',
'flex-wrap',
'gap',
'column-gap',
'row-gap',
'grid-template-columns',
'grid-auto-columns',
'grid-column-start',
'grid-column-end',
'grid-column',
'grid-column-gap',
'grid-template-rows',
'grid-auto-rows',
'grid-row-start',
'grid-row-end',
'grid-row',
'grid-row-gap',
'grid-gap',
'justify-content',
'justify-items',
'justify-self',
'align-content',
'align-items',
'align-self',
'clear',
'cursor',
'direction',
'float',
'list-style-type',
'object-fit',
'object-position',
'overflow',
'vertical-align',
'writing-mode',
'position',
'top',
'right',
'bottom',
'left',
'z-index',
'box-shadow',
'aspect-ratio',
'container-type',
// Custom CSS properties.
'--*',
)
);
/*
* CSS attributes that accept URL data types.
*
* This is in accordance to the CSS spec and unrelated to
* the sub-set of supported attributes above.
*
* See: https://developer.mozilla.org/en-US/docs/Web/CSS/url
*/
$css_url_data_types = array(
'background',
'background-image',
'cursor',
'filter',
'list-style',
'list-style-image',
);
/*
* CSS attributes that accept gradient data types.
*
*/
$css_gradient_data_types = array(
'background',
'background-image',
);
if ( empty( $allowed_attr ) ) {
return $css;
}
$css = '';
foreach ( $css_array as $css_item ) {
if ( '' === $css_item ) {
continue;
}
$css_item = trim( $css_item );
$css_test_string = $css_item;
$found = false;
$url_attr = false;
$gradient_attr = false;
$is_custom_var = false;
if ( ! str_contains( $css_item, ':' ) ) {
$found = true;
} else {
$parts = explode( ':', $css_item, 2 );
$css_selector = trim( $parts[0] );
// Allow assigning values to CSS variables.
if ( in_array( '--*', $allowed_attr, true ) && preg_match( '/^--[a-zA-Z0-9-_]+$/', $css_selector ) ) {
$allowed_attr[] = $css_selector;
$is_custom_var = true;
}
if ( in_array( $css_selector, $allowed_attr, true ) ) {
$found = true;
$url_attr = in_array( $css_selector, $css_url_data_types, true );
$gradient_attr = in_array( $css_selector, $css_gradient_data_types, true );
}
if ( $is_custom_var ) {
$css_value = trim( $parts[1] );
$url_attr = str_starts_with( $css_value, 'url(' );
$gradient_attr = str_contains( $css_value, '-gradient(' );
}
}
if ( $found && $url_attr ) {
// Simplified: matches the sequence `url(*)`.
preg_match_all( '/url\([^)]+\)/', $parts[1], $url_matches );
foreach ( $url_matches[0] as $url_match ) {
// Clean up the URL from each of the matches above.
preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/', $url_match, $url_pieces );
if ( empty( $url_pieces[2] ) ) {
$found = false;
break;
}
$url = trim( $url_pieces[2] );
if ( empty( $url ) || wp_kses_bad_protocol( $url, $allowed_protocols ) !== $url ) {
$found = false;
break;
} else {
// Remove the whole `url(*)` bit that was matched above from the CSS.
$css_test_string = str_replace( $url_match, '', $css_test_string );
}
}
}
if ( $found && $gradient_attr ) {
$css_value = trim( $parts[1] );
if ( preg_match( '/^(repeating-)?(linear|radial|conic)-gradient\(([^()]|rgb[a]?\([^()]*\))*\)$/', $css_value ) ) {
// Remove the whole `gradient` bit that was matched above from the CSS.
$css_test_string = str_replace( $css_value, '', $css_test_string );
}
}
if ( $found ) {
/*
* Allow CSS functions like var(), calc(), etc. by removing them from the test string.
* Nested functions and parentheses are also removed, so long as the parentheses are balanced.
*/
$css_test_string = preg_replace(
'/\b(?:var|calc|min|max|minmax|clamp|repeat)(\((?:[^()]|(?1))*\))/',
'',
$css_test_string
);
/*
* Disallow CSS containing \ ( & } = or comments, except for within url(), var(), calc(), etc.
* which were removed from the test string above.
*/
$allow_css = ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string );
/**
* Filters the check for unsafe CSS in `safecss_filter_attr`.
*
* Enables developers to determine whether a section of CSS should be allowed or discarded.
* By default, the value will be false if the part contains \ ( & } = or comments.
* Return true to allow the CSS part to be included in the output.
*
* @since 5.5.0
*
* @param bool $allow_css Whether the CSS in the test string is considered safe.
* @param string $css_test_string The CSS string to test.
*/
$allow_css = apply_filters( 'safecss_filter_attr_allow_css', $allow_css, $css_test_string );
// Only add the CSS part if it passes the regex check.
if ( $allow_css ) {
if ( '' !== $css ) {
$css .= ';';
}
$css .= $css_item;
}
}
}
return $css;
}
/**
* Helper function to add global attributes to a tag in the allowed HTML list.
*
* @since 3.5.0
* @since 5.0.0 Added support for `data-*` wildcard attributes.
* @since 6.0.0 Added `dir`, `lang`, and `xml:lang` to global attributes.
* @since 6.3.0 Added `aria-controls`, `aria-current`, and `aria-expanded` attributes.
* @since 6.4.0 Added `aria-live` and `hidden` attributes.
*
* @access private
* @ignore
*
* @param array $value An array of attributes.
* @return array The array of attributes with global attributes added.
*/
function _wp_add_global_attributes( $value ) {
$global_attributes = array(
'aria-controls' => true,
'aria-current' => true,
'aria-describedby' => true,
'aria-details' => true,
'aria-expanded' => true,
'aria-hidden' => true,
'aria-label' => true,
'aria-labelledby' => true,
'aria-live' => true,
'class' => true,
'data-*' => true,
'dir' => true,
'hidden' => true,
'id' => true,
'lang' => true,
'style' => true,
'title' => true,
'role' => true,
'xml:lang' => true,
);
if ( true === $value ) {
$value = array();
}
if ( is_array( $value ) ) {
return array_merge( $value, $global_attributes );
}
return $value;
}
/**
* Helper function to check if this is a safe PDF URL.
*
* @since 5.9.0
* @access private
* @ignore
*
* @param string $url The URL to check.
* @return bool True if the URL is safe, false otherwise.
*/
function _wp_kses_allow_pdf_objects( $url ) {
// We're not interested in URLs that contain query strings or fragments.
if ( str_contains( $url, '?' ) || str_contains( $url, '#' ) ) {
return false;
}
// If it doesn't have a PDF extension, it's not safe.
if ( ! str_ends_with( $url, '.pdf' ) ) {
return false;
}
// If the URL host matches the current site's media URL, it's safe.
$upload_info = wp_upload_dir( null, false );
$parsed_url = wp_parse_url( $upload_info['url'] );
$upload_host = isset( $parsed_url['host'] ) ? $parsed_url['host'] : '';
$upload_port = isset( $parsed_url['port'] ) ? ':' . $parsed_url['port'] : '';
if ( str_starts_with( $url, "http://$upload_host$upload_port/" )
|| str_starts_with( $url, "https://$upload_host$upload_port/" )
) {
return true;
}
return false;
}