` 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( $content, '<' ) ) {
return '>';
}
/*
* When certain invalid syntax constructs appear, the HTML parser
* shifts into what's called the "bogus comment state." This is a
* plaintext state that consumes everything until the nearest `>`
* and then transforms the entire span into an HTML comment.
*
* Preserve these comments and do not treat them like tags.
*
* @see https://html.spec.whatwg.org/#bogus-comment-state
*/
if ( 1 === preg_match( '~^(?:]*>|]*>)$~', $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 );
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.
$content = preg_replace( '/-$/', '', $content );
return "";
}
// It's seriously malformed.
if ( ! preg_match( '%^<\s*(/\s*)?([a-zA-Z0-9-]+)([^>]*)>?$%', $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 "";
}
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 `
`) or not (``). 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( '/(�*58(?![;0-9])|�*3a(?![;a-f0-9]))/i', '$1;', $content );
$content2 = preg_split( '/:|�*58;|�*3a;|:/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&T`, `:` to `:`, `&#XYZZY;` to `&#XYZZY;` and so on.
*
* When `$context` is set to 'xml', HTML entities are converted to their code points. For
* example, `AT&T…&#XYZZY;` is converted to `AT&T…&#XYZZY;`.
*
* @since 1.0.0
* @since 5.5.0 Added `$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 &
$content = str_replace( '&', '&', $content );
/*
* Decode any character references that are now double-encoded.
*
* It's important that the following normalizations happen in the correct order.
*
* At this point, all `&` have been transformed to `&`. Double-encoded named character
* references like `&` will be decoded back to their single-encoded form `&`.
*
* First, numeric (decimal and hexadecimal) character references must be handled so that
* `	` becomes ` `. If the named character references were handled first, there
* would be no way to know whether the double-encoded character reference had been produced
* in this function or was the original input.
*
* Consider the two examples, first with named entity decoding followed by numeric
* entity decoding. We'll use U+002E FULL STOP (.) in our example, this table follows the
* string processing from left to right:
*
* | Input | &-encoded | Named ref double-decoded | Numeric ref double-decoded |
* | ------------ | ---------------- | ------------------------- | -------------------------- |
* | `.` | `.` | `.` | `.` |
* | `.` | `&#x2E;` | `.` | `.` |
*
* Notice in the example above that different inputs result in the same result. The second case
* was not normalized and produced HTML that is semantically different from the input.
*
* | Input | &-encoded | Numeric ref double-decoded | Named ref double-decoded |
* | ------------ | ---------------- | --------------------------- | ------------------------ |
* | `.` | `.` | `.` | `.` |
* | `.` | `&#x2E;` | `&#x2E;` | `.` |
*
* Here, each input is normalized to an appropriate output.
*/
$content = preg_replace_callback( '/&#(0*[0-9]{1,7});/', 'wp_kses_normalize_entities2', $content );
$content = preg_replace_callback( '/&#[Xx](0*[0-9A-Fa-f]{1,6});/', 'wp_kses_normalize_entities3', $content );
if ( 'xml' === $context ) {
$content = preg_replace_callback( '/&([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_xml_named_entities', $content );
} else {
$content = preg_replace_callback( '/&([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_named_entities', $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, $allowedentitynames, true ) ) ? "&$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 "&$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 {
$i = "&#$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( $hexchars ) ) ) ? "&#x$hexchars;" : '&#x' . ltrim( $hexchars, '0' ) . ';';
}
/**
* Determines if a Unicode codepoint is valid.
*
* The definition of a valid Unicode codepoint is taken from the XML definition:
*
* > Characters
* >
* > …
* > Legal characters are tab, carriage return, line feed, and the legal characters of
* > Unicode and ISO/IEC 10646.
* > …
* > Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
*
* @since 2.7.0
*
* @see https://www.w3.org/TR/xml/#charsets
*
* @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 || // U+0009 HORIZONTAL TABULATION (HT)
0xA === $i || // U+000A LINE FEED (LF)
0xD === $i || // U+000D CARRIAGE RETURN (CR)
/*
* The valid Unicode characters according to the XML specification:
*
* > any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.
*/
( 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 (`A` and `A`).
* It doesn't do anything with named entities like `ä`, 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`.
* @since 6.9.0 Added support for `white-space`.
*
* @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',
'white-space',
'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',
'opacity',
'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;
}