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<?php
namespace MediaWiki\Parser;
use Wikimedia\RemexHtml\Tokenizer\Attributes;
use Wikimedia\RemexHtml\Tokenizer\PlainAttributes;
use Wikimedia\RemexHtml\Tokenizer\RelayTokenHandler;
use Wikimedia\RemexHtml\Tokenizer\TokenHandler;
/**
* Helper class for Sanitizer::removeSomeTags().
* @internal
*/
class RemexRemoveTagHandler extends RelayTokenHandler {
/**
* @var string The original HTML source string (used for fallback text
* when rejecting an HTML tag).
*/
private $source;
/**
* @var array<string,true> Set of HTML tags which can be self-closed.
*/
private $htmlsingle;
/**
* @var array<string,true> Self-closed tags which are on $htmlsingle
* but not on $htmlsingleonly will be emitted as an empty element.
*/
private $htmlsingleonly;
/**
* @var array<string,true> Set of allowed HTML open/close tags.
*/
private $htmlelements;
/**
* @var ?callable(Attributes,mixed...):Attributes Callback to mutate or
* sanitize attributes.
*/
private $attrCallback;
/**
* @var ?array $args Optional extra arguments to provide to the
* $attrCallback.
*/
private $callbackArgs;
/**
* @param TokenHandler $nextHandler Handler to relay accepted tokens.
* @param string $source Input source string.
* @param array $tagData Information about allowed/rejected tags.
* @param ?callable $attrCallback Attribute handler callback.
* The full signature is ?callable(Attributes,mixed...):Attributes
* @param ?array $callbackArgs Optional arguments to attribute handler.
*/
public function __construct(
TokenHandler $nextHandler,
string $source,
array $tagData,
?callable $attrCallback,
?array $callbackArgs
) {
parent::__construct( $nextHandler );
$this->source = $source;
$this->htmlsingle = $tagData['htmlsingle'];
$this->htmlsingleonly = $tagData['htmlsingleonly'];
$this->htmlelements = $tagData['htmlelements'];
$this->attrCallback = $attrCallback;
$this->callbackArgs = $callbackArgs ?? [];
}
/**
* @inheritDoc
*/
public function comment( $text, $sourceStart, $sourceLength ) {
// Don't relay comments.
}
/**
* Takes attribute names and values for a tag and the tag name and
* validates that the tag is allowed to be present.
* This DOES NOT validate the attributes, nor does it validate the
* tags themselves. This method only handles the special circumstances
* where we may want to allow a tag within content but ONLY when it has
* specific attributes set.
*
* @param string $element
* @param Attributes $attrs
* @return bool
*
* @see Sanitizer::validateTag()
*/
private static function validateTag( string $element, Attributes $attrs ): bool {
if ( $element == 'meta' || $element == 'link' ) {
$params = $attrs->getValues();
if ( !isset( $params['itemprop'] ) ) {
// <meta> and <link> must have an itemprop="" otherwise they are not valid or safe in content
return false;
}
if ( $element == 'meta' && !isset( $params['content'] ) ) {
// <meta> must have a content="" for the itemprop
return false;
}
if ( $element == 'link' && !isset( $params['href'] ) ) {
// <link> must have an associated href=""
return false;
}
}
return true;
}
/**
* @inheritDoc
*/
public function startTag( $name, Attributes $attrs, $selfClose, $sourceStart, $sourceLength ) {
// Handle a start tag from the tokenizer: either relay it to the
// next stage, or re-emit it as raw text.
$badtag = false;
$t = strtolower( $name );
if ( isset( $this->htmlelements[$t] ) ) {
if ( $this->attrCallback ) {
$attrs = ( $this->attrCallback )( $attrs, ...$this->callbackArgs );
}
if ( $selfClose && !( isset( $this->htmlsingle[$t] ) || isset( $this->htmlsingleonly[$t] ) ) ) {
// Remove the self-closing slash, to be consistent with
// HTML5 semantics. T134423
$selfClose = false;
}
if ( !self::validateTag( $t, $attrs ) ) {
$badtag = true;
}
$fixedAttrs = Sanitizer::validateTagAttributes( $attrs->getValues(), $t );
$attrs = new PlainAttributes( $fixedAttrs );
if ( !$badtag ) {
if ( $selfClose && !isset( $this->htmlsingleonly[$t] ) ) {
// Interpret self-closing tags as empty tags even when
// HTML5 would interpret them as start tags. Such input
// is commonly seen on Wikimedia wikis with this intention.
$this->nextHandler->startTag( $name, $attrs, false, $sourceStart, $sourceLength );
$this->nextHandler->endTag( $name, $sourceStart + $sourceLength, 0 );
} else {
$this->nextHandler->startTag( $name, $attrs, $selfClose, $sourceStart, $sourceLength );
}
return;
}
}
// Emit this as a text node instead.
$this->nextHandler->characters( $this->source, $sourceStart, $sourceLength, $sourceStart, $sourceLength );
}
/**
* @inheritDoc
*/
public function endTag( $name, $sourceStart, $sourceLength ) {
// Handle an end tag from the tokenizer: either relay it to the
// next stage, or re-emit it as raw text.
$t = strtolower( $name );
if ( isset( $this->htmlelements[$t] ) ) {
// This is a good tag, relay it.
$this->nextHandler->endTag( $name, $sourceStart, $sourceLength );
} else {
// Emit this as a text node instead.
$this->nextHandler->characters( $this->source, $sourceStart, $sourceLength, $sourceStart, $sourceLength );
}
}
}
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