3 * XHTML sanitizer for MediaWiki
5 * Copyright © 2002-2005 Brion Vibber <brion@pobox.com> et al
6 * http://www.mediawiki.org/
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
21 * http://www.gnu.org/copyleft/gpl.html
28 * XHTML sanitizer for MediaWiki
33 * Regular expression to match various types of character references in
34 * Sanitizer::normalizeCharReferences and Sanitizer::decodeCharReferences
36 const CHAR_REFS_REGEX
=
37 '/&([A-Za-z0-9\x80-\xff]+);
39 |&\#[xX]([0-9A-Fa-f]+);
43 * Blacklist for evil uris like javascript:
44 * WARNING: DO NOT use this in any place that actually requires blacklisting
45 * for security reasons. There are NUMEROUS[1] ways to bypass blacklisting, the
46 * only way to be secure from javascript: uri based xss vectors is to whitelist
47 * things that you know are safe and deny everything else.
48 * [1]: http://ha.ckers.org/xss.html
50 const EVIL_URI_PATTERN
= '!(^|\s|\*/\s*)(javascript|vbscript)([^\w]|$)!i';
51 const XMLNS_ATTRIBUTE_PATTERN
= "/^xmlns:[:A-Z_a-z-.0-9]+$/";
54 * List of all named character entities defined in HTML 4.01
55 * http://www.w3.org/TR/html4/sgml/entities.html
56 * As well as ' which is only defined starting in XHTML1.
59 static $htmlEntities = array(
75 'apos' => 39, // New in XHTML & HTML 5; avoid in output for compatibility with IE.
316 * Character entity aliases accepted by MediaWiki
318 static $htmlEntityAliases = array(
324 * Lazy-initialised attributes regex, see getAttribsRegex()
326 static $attribsRegex;
329 * Regular expression to match HTML/XML attribute pairs within a tag.
330 * Allows some... latitude.
331 * Used in Sanitizer::fixTagAttributes and Sanitizer::decodeTagAttributes
333 static function getAttribsRegex() {
334 if ( self
::$attribsRegex === null ) {
335 $attribFirst = '[:A-Z_a-z0-9]';
336 $attrib = '[:A-Z_a-z-.0-9]';
337 $space = '[\x09\x0a\x0d\x20]';
338 self
::$attribsRegex =
339 "/(?:^|$space)({$attribFirst}{$attrib}*)
342 # The attribute value: quoted or alone
345 | ([a-zA-Z0-9!#$%&()*,\\-.\\/:;<>?@[\\]^_`{|}~]+)
346 | (\#[0-9a-fA-F]+) # Technically wrong, but lots of
347 # colors are specified like this.
348 # We'll be normalizing it.
352 return self
::$attribsRegex;
356 * Cleans up HTML, removes dangerous tags and attributes, and
357 * removes HTML comments
359 * @param $text String
360 * @param $processCallback Callback to do any variable or parameter replacements in HTML attribute values
361 * @param $args Array for the processing callback
362 * @param $extratags Array for any extra tags to include
363 * @param $removetags Array for any tags (default or extra) to exclude
366 static function removeHTMLtags( $text, $processCallback = null, $args = array(), $extratags = array(), $removetags = array() ) {
369 static $htmlpairsStatic, $htmlsingle, $htmlsingleonly, $htmlnest, $tabletags,
370 $htmllist, $listtags, $htmlsingleallowed, $htmlelementsStatic, $staticInitialised;
372 wfProfileIn( __METHOD__
);
374 if ( !$staticInitialised ) {
376 $htmlpairsStatic = array( # Tags that must be closed
377 'b', 'del', 'i', 'ins', 'u', 'font', 'big', 'small', 'sub', 'sup', 'h1',
378 'h2', 'h3', 'h4', 'h5', 'h6', 'cite', 'code', 'em', 's',
379 'strike', 'strong', 'tt', 'var', 'div', 'center',
380 'blockquote', 'ol', 'ul', 'dl', 'table', 'caption', 'pre',
381 'ruby', 'rt' , 'rb' , 'rp', 'p', 'span', 'abbr', 'dfn',
385 'br', 'hr', 'li', 'dt', 'dd'
387 $htmlsingleonly = array( # Elements that cannot have close tags
390 $htmlnest = array( # Tags that can be nested--??
391 'table', 'tr', 'td', 'th', 'div', 'blockquote', 'ol', 'ul',
392 'dl', 'font', 'big', 'small', 'sub', 'sup', 'span'
394 $tabletags = array( # Can only appear inside table, we will close them
397 $htmllist = array( # Tags used by list
400 $listtags = array( # Tags that can appear in a list
404 global $wgAllowImageTag;
405 if ( $wgAllowImageTag ) {
406 $htmlsingle[] = 'img';
407 $htmlsingleonly[] = 'img';
410 $htmlsingleallowed = array_unique( array_merge( $htmlsingle, $tabletags ) );
411 $htmlelementsStatic = array_unique( array_merge( $htmlsingle, $htmlpairsStatic, $htmlnest ) );
413 # Convert them all to hashtables for faster lookup
414 $vars = array( 'htmlpairsStatic', 'htmlsingle', 'htmlsingleonly', 'htmlnest', 'tabletags',
415 'htmllist', 'listtags', 'htmlsingleallowed', 'htmlelementsStatic' );
416 foreach ( $vars as $var ) {
417 $
$var = array_flip( $
$var );
419 $staticInitialised = true;
421 # Populate $htmlpairs and $htmlelements with the $extratags and $removetags arrays
422 $extratags = array_flip( $extratags );
423 $removetags = array_flip( $removetags );
424 $htmlpairs = array_merge( $extratags, $htmlpairsStatic );
425 $htmlelements = array_diff_key( array_merge( $extratags, $htmlelementsStatic ) , $removetags );
427 # Remove HTML comments
428 $text = Sanitizer
::removeHTMLcomments( $text );
429 $bits = explode( '<', $text );
430 $text = str_replace( '>', '>', array_shift( $bits ) );
432 $tagstack = $tablestack = array();
433 foreach ( $bits as $x ) {
435 # $slash: Does the current element start with a '/'?
436 # $t: Current element name
437 # $params: String between element name and >
438 # $brace: Ending '>' or '/>'
439 # $rest: Everything until the next element of $bits
440 if( preg_match( '!^(/?)(\\w+)([^>]*?)(/{0,1}>)([^<]*)$!', $x, $regs ) ) {
441 list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
443 $slash = $t = $params = $brace = $rest = null;
447 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
449 if ( $slash && isset( $htmlsingleonly[$t] ) ) {
451 } elseif ( $slash ) {
452 # Closing a tag... is it the one we just opened?
453 $ot = @array_pop
( $tagstack );
455 if ( isset( $htmlsingleallowed[$ot] ) ) {
456 # Pop all elements with an optional close tag
457 # and see if we find a match below them
459 array_push( $optstack, $ot );
460 $ot = @array_pop
( $tagstack );
461 while ( $ot != $t && isset( $htmlsingleallowed[$ot] ) ) {
462 array_push( $optstack, $ot );
463 $ot = @array_pop
( $tagstack );
466 # No match. Push the optional elements back again
468 while ( $ot = @array_pop
( $optstack ) ) {
469 array_push( $tagstack, $ot );
473 @array_push
( $tagstack, $ot );
474 # <li> can be nested in <ul> or <ol>, skip those cases:
475 if ( !isset( $htmllist[$ot] ) ||
!isset( $listtags[$t] ) ) {
480 if ( $t == 'table' ) {
481 $tagstack = array_pop( $tablestack );
486 # Keep track for later
487 if ( isset( $tabletags[$t] ) &&
488 !in_array( 'table', $tagstack ) ) {
490 } elseif ( in_array( $t, $tagstack ) &&
491 !isset( $htmlnest [$t ] ) ) {
493 # Is it a self closed htmlpair ? (bug 5487)
494 } elseif ( $brace == '/>' &&
495 isset( $htmlpairs[$t] ) ) {
497 } elseif ( isset( $htmlsingleonly[$t] ) ) {
498 # Hack to force empty tag for uncloseable elements
500 } elseif ( isset( $htmlsingle[$t] ) ) {
501 # Hack to not close $htmlsingle tags
503 } elseif ( isset( $tabletags[$t] )
504 && in_array( $t, $tagstack ) ) {
505 // New table tag but forgot to close the previous one
508 if ( $t == 'table' ) {
509 array_push( $tablestack, $tagstack );
512 array_push( $tagstack, $t );
515 # Replace any variables or template parameters with
517 if( is_callable( $processCallback ) ) {
518 call_user_func_array( $processCallback, array( &$params, $args ) );
521 # Strip non-approved attributes from the tag
522 $newparams = Sanitizer
::fixTagAttributes( $params, $t );
525 $rest = str_replace( '>', '>', $rest );
526 $close = ( $brace == '/>' && !$slash ) ?
' /' : '';
527 $text .= "<$slash$t$newparams$close>$rest";
531 $text .= '<' . str_replace( '>', '>', $x);
533 # Close off any remaining tags
534 while ( is_array( $tagstack ) && ($t = array_pop( $tagstack )) ) {
536 if ( $t == 'table' ) { $tagstack = array_pop( $tablestack ); }
539 # this might be possible using tidy itself
540 foreach ( $bits as $x ) {
541 preg_match( '/^(\\/?)(\\w+)([^>]*?)(\\/{0,1}>)([^<]*)$/',
543 @list
( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
544 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
545 if( is_callable( $processCallback ) ) {
546 call_user_func_array( $processCallback, array( &$params, $args ) );
548 $newparams = Sanitizer
::fixTagAttributes( $params, $t );
549 $rest = str_replace( '>', '>', $rest );
550 $text .= "<$slash$t$newparams$brace$rest";
552 $text .= '<' . str_replace( '>', '>', $x);
556 wfProfileOut( __METHOD__
);
561 * Remove '<!--', '-->', and everything between.
562 * To avoid leaving blank lines, when a comment is both preceded
563 * and followed by a newline (ignoring spaces), trim leading and
564 * trailing spaces and one of the newlines.
567 * @param $text String
570 static function removeHTMLcomments( $text ) {
571 wfProfileIn( __METHOD__
);
572 while (($start = strpos($text, '<!--')) !== false) {
573 $end = strpos($text, '-->', $start +
4);
574 if ($end === false) {
575 # Unterminated comment; bail out
581 # Trim space and newline if the comment is both
582 # preceded and followed by a newline
583 $spaceStart = max($start - 1, 0);
584 $spaceLen = $end - $spaceStart;
585 while (substr($text, $spaceStart, 1) === ' ' && $spaceStart > 0) {
589 while (substr($text, $spaceStart +
$spaceLen, 1) === ' ')
591 if (substr($text, $spaceStart, 1) === "\n" and substr($text, $spaceStart +
$spaceLen, 1) === "\n") {
592 # Remove the comment, leading and trailing
593 # spaces, and leave only one newline.
594 $text = substr_replace($text, "\n", $spaceStart, $spaceLen +
1);
597 # Remove just the comment.
598 $text = substr_replace($text, '', $start, $end - $start);
601 wfProfileOut( __METHOD__
);
606 * Take an array of attribute names and values and fix some deprecated values
607 * for the given element type.
608 * This does not validate properties, so you should ensure that you call
609 * validateTagAttributes AFTER this to ensure that the resulting style rule
610 * this may add is safe.
612 * - Converts most presentational attributes like align into inline css
614 * @param $attribs Array
615 * @param $element String
618 static function fixDeprecatedAttributes( $attribs, $element ) {
619 global $wgHtml5, $wgCleanupPresentationalAttributes;
621 // presentational attributes were removed from html5, we can leave them
622 // in when html5 is turned off
623 if ( !$wgHtml5 ||
!$wgCleanupPresentationalAttributes ) {
627 $table = array( 'table' );
628 $cells = array( 'td', 'th' );
629 $colls = array( 'col', 'colgroup' );
630 $tblocks = array( 'tbody', 'tfoot', 'thead' );
631 $h = array( 'h1', 'h2', 'h3', 'h4', 'h5', 'h6' );
633 $presentationalAttribs = array(
634 'align' => array( 'text-align', array_merge( array( 'caption', 'hr', 'div', 'p', 'tr' ), $table, $cells, $colls, $tblocks, $h ) ),
635 'clear' => array( 'clear', array( 'br' ) ),
636 'height' => array( 'height', $cells ),
637 'nowrap' => array( 'white-space', $cells ),
638 'size' => array( 'height', array( 'hr' ) ),
639 'type' => array( 'list-style-type', array( 'li', 'ol', 'ul' ) ),
640 'valign' => array( 'vertical-align', array_merge( $cells, $colls, $tblocks ) ),
641 'width' => array( 'width', array_merge( array( 'hr', 'pre' ), $table, $cells, $colls ) ),
644 // Ensure that any upper case or mixed case attributes are converted to lowercase
645 foreach ( $attribs as $attribute => $value ) {
646 if ( $attribute !== strtolower( $attribute ) && array_key_exists( strtolower( $attribute ), $presentationalAttribs ) ) {
647 $attribs[strtolower( $attribute )] = $value;
648 unset( $attribs[$attribute] );
653 foreach ( $presentationalAttribs as $attribute => $info ) {
654 list( $property, $elements ) = $info;
656 // Skip if this attribute is not relevant to this element
657 if ( !in_array( $element, $elements ) ) {
661 // Skip if the attribute is not used
662 if ( !array_key_exists( $attribute, $attribs ) ) {
666 $value = $attribs[$attribute];
668 // For nowrap the value should be nowrap instead of whatever text is in the value
669 if ( $attribute === 'nowrap' ) {
673 // clear="all" is clear: both; in css
674 if ( $attribute === 'clear' && strtolower( $value ) === 'all' ) {
678 // Size based properties should have px applied to them if they have no unit
679 if ( in_array( $attribute, array( 'height', 'width', 'size' ) ) ) {
680 if ( preg_match( '/^[\d.]+$/', $value ) ) {
681 $value = "{$value}px";
685 $style .= " $property: $value;";
687 unset( $attribs[$attribute] );
691 // Prepend our style rules so that they can be overridden by user css
692 if ( isset($attribs['style']) ) {
693 $style .= " " . $attribs['style'];
695 $attribs['style'] = trim($style);
702 * Take an array of attribute names and values and normalize or discard
703 * illegal values for the given element type.
705 * - Discards attributes not on a whitelist for the given element
706 * - Unsafe style attributes are discarded
707 * - Invalid id attributes are reencoded
709 * @param $attribs Array
710 * @param $element String
713 * @todo Check for legal values where the DTD limits things.
714 * @todo Check for unique id attribute :P
716 static function validateTagAttributes( $attribs, $element ) {
717 return Sanitizer
::validateAttributes( $attribs,
718 Sanitizer
::attributeWhitelist( $element ) );
722 * Take an array of attribute names and values and normalize or discard
723 * illegal values for the given whitelist.
725 * - Discards attributes not the given whitelist
726 * - Unsafe style attributes are discarded
727 * - Invalid id attributes are reencoded
729 * @param $attribs Array
730 * @param $whitelist Array: list of allowed attribute names
733 * @todo Check for legal values where the DTD limits things.
734 * @todo Check for unique id attribute :P
736 static function validateAttributes( $attribs, $whitelist ) {
737 global $wgAllowRdfaAttributes, $wgAllowMicrodataAttributes, $wgHtml5;
739 $whitelist = array_flip( $whitelist );
740 $hrefExp = '/^(' . wfUrlProtocols() . ')[^\s]+$/';
743 foreach( $attribs as $attribute => $value ) {
744 #allow XML namespace declaration if RDFa is enabled
745 if ( $wgAllowRdfaAttributes && preg_match( self
::XMLNS_ATTRIBUTE_PATTERN
, $attribute ) ) {
746 if ( !preg_match( self
::EVIL_URI_PATTERN
, $value ) ) {
747 $out[$attribute] = $value;
753 # Allow any attribute beginning with "data-", if in HTML5 mode
754 if ( !($wgHtml5 && preg_match( '/^data-/i', $attribute )) && !isset( $whitelist[$attribute] ) ) {
758 # Strip javascript "expression" from stylesheets.
759 # http://msdn.microsoft.com/workshop/author/dhtml/overview/recalc.asp
760 if( $attribute == 'style' ) {
761 $value = Sanitizer
::checkCss( $value );
764 if ( $attribute === 'id' ) {
765 $value = Sanitizer
::escapeId( $value, 'noninitial' );
768 //RDFa and microdata properties allow URLs, URIs and/or CURIs. check them for sanity
769 if ( $attribute === 'rel' ||
$attribute === 'rev' ||
770 $attribute === 'about' ||
$attribute === 'property' ||
$attribute === 'resource' ||
#RDFa
771 $attribute === 'datatype' ||
$attribute === 'typeof' ||
#RDFa
772 $attribute === 'itemid' ||
$attribute === 'itemprop' ||
$attribute === 'itemref' ||
#HTML5 microdata
773 $attribute === 'itemscope' ||
$attribute === 'itemtype' ) { #HTML5 microdata
775 //Paranoia. Allow "simple" values but suppress javascript
776 if ( preg_match( self
::EVIL_URI_PATTERN
, $value ) ) {
781 # NOTE: even though elements using href/src are not allowed directly, supply
782 # validation code that can be used by tag hook handlers, etc
783 if ( $attribute === 'href' ||
$attribute === 'src' ) {
784 if ( !preg_match( $hrefExp, $value ) ) {
785 continue; //drop any href or src attributes not using an allowed protocol.
786 //NOTE: this also drops all relative URLs
790 // If this attribute was previously set, override it.
791 // Output should only have one attribute of each name.
792 $out[$attribute] = $value;
795 if ( $wgAllowMicrodataAttributes ) {
796 # itemtype, itemid, itemref don't make sense without itemscope
797 if ( !array_key_exists( 'itemscope', $out ) ) {
798 unset( $out['itemtype'] );
799 unset( $out['itemid'] );
800 unset( $out['itemref'] );
802 # TODO: Strip itemprop if we aren't descendants of an itemscope.
808 * Merge two sets of HTML attributes. Conflicting items in the second set
809 * will override those in the first, except for 'class' attributes which
810 * will be combined (if they're both strings).
812 * @todo implement merging for other attributes such as style
817 static function mergeAttributes( $a, $b ) {
818 $out = array_merge( $a, $b );
819 if( isset( $a['class'] ) && isset( $b['class'] )
820 && is_string( $a['class'] ) && is_string( $b['class'] )
821 && $a['class'] !== $b['class'] ) {
822 $classes = preg_split( '/\s+/', "{$a['class']} {$b['class']}",
823 -1, PREG_SPLIT_NO_EMPTY
);
824 $out['class'] = implode( ' ', array_unique( $classes ) );
830 * Pick apart some CSS and check it for forbidden or unsafe structures.
831 * Returns a sanitized string. This sanitized string will have
832 * character references and escape sequences decoded, and comments
833 * stripped. If the input is just too evil, only a comment complaining
834 * about evilness will be returned.
836 * Currently URL references, 'expression', 'tps' are forbidden.
838 * NOTE: Despite the fact that character references are decoded, the
839 * returned string may contain character references given certain
840 * clever input strings. These character references must
841 * be escaped before the return value is embedded in HTML.
843 * @param $value String
846 static function checkCss( $value ) {
847 // Decode character references like {
848 $value = Sanitizer
::decodeCharReferences( $value );
850 // Decode escape sequences and line continuation
851 // See the grammar in the CSS 2 spec, appendix D.
852 // This has to be done AFTER decoding character references.
853 // This means it isn't possible for this function to return
854 // unsanitized escape sequences. It is possible to manufacture
855 // input that contains character references that decode to
856 // escape sequences that decode to character references, but
857 // it's OK for the return value to contain character references
858 // because the caller is supposed to escape those anyway.
860 if ( !$decodeRegex ) {
861 $space = '[\\x20\\t\\r\\n\\f]';
862 $nl = '(?:\\n|\\r\\n|\\r|\\f)';
864 $decodeRegex = "/ $backslash
866 ($nl) | # 1. Line continuation
867 ([0-9A-Fa-f]{1,6})$space? | # 2. character number
868 (.) | # 3. backslash cancelling special meaning
869 () | # 4. backslash at end of string
872 $value = preg_replace_callback( $decodeRegex,
873 array( __CLASS__
, 'cssDecodeCallback' ), $value );
875 // Remove any comments; IE gets token splitting wrong
876 // This must be done AFTER decoding character references and
877 // escape sequences, because those steps can introduce comments
878 // This step cannot introduce character references or escape
879 // sequences, because it replaces comments with spaces rather
880 // than removing them completely.
881 $value = StringUtils
::delimiterReplace( '/*', '*/', ' ', $value );
883 // Remove anything after a comment-start token, to guard against
884 // incorrect client implementations.
885 $commentPos = strpos( $value, '/*' );
886 if ( $commentPos !== false ) {
887 $value = substr( $value, 0, $commentPos );
890 // Reject problematic keywords and control characters
891 if ( preg_match( '/[\000-\010\016-\037\177]/', $value ) ) {
892 return '/* invalid control char */';
893 } elseif ( preg_match( '! expression | filter\s*: | accelerator\s*: | url\s*\( !ix', $value ) ) {
894 return '/* insecure input */';
900 * @param $matches array
903 static function cssDecodeCallback( $matches ) {
904 if ( $matches[1] !== '' ) {
907 } elseif ( $matches[2] !== '' ) {
908 $char = codepointToUtf8( hexdec( $matches[2] ) );
909 } elseif ( $matches[3] !== '' ) {
914 if ( $char == "\n" ||
$char == '"' ||
$char == "'" ||
$char == '\\' ) {
915 // These characters need to be escaped in strings
916 // Clean up the escape sequence to avoid parsing errors by clients
917 return '\\' . dechex( ord( $char ) ) . ' ';
919 // Decode unnecessary escape
925 * Take a tag soup fragment listing an HTML element's attributes
926 * and normalize it to well-formed XML, discarding unwanted attributes.
927 * Output is safe for further wikitext processing, with escaping of
928 * values that could trigger problems.
930 * - Normalizes attribute names to lowercase
931 * - Discards attributes not on a whitelist for the given element
932 * - Turns broken or invalid entities into plaintext
933 * - Double-quotes all attribute values
934 * - Attributes without values are given the name as attribute
935 * - Double attributes are discarded
936 * - Unsafe style attributes are discarded
937 * - Prepends space if there are attributes.
939 * @param $text String
940 * @param $element String
943 static function fixTagAttributes( $text, $element ) {
944 if( trim( $text ) == '' ) {
948 $decoded = Sanitizer
::decodeTagAttributes( $text );
949 $decoded = Sanitizer
::fixDeprecatedAttributes( $decoded, $element );
950 $stripped = Sanitizer
::validateTagAttributes( $decoded, $element );
953 foreach( $stripped as $attribute => $value ) {
954 $encAttribute = htmlspecialchars( $attribute );
955 $encValue = Sanitizer
::safeEncodeAttribute( $value );
957 $attribs[] = "$encAttribute=\"$encValue\"";
959 return count( $attribs ) ?
' ' . implode( ' ', $attribs ) : '';
963 * Encode an attribute value for HTML output.
964 * @param $text String
965 * @return HTML-encoded text fragment
967 static function encodeAttribute( $text ) {
968 $encValue = htmlspecialchars( $text, ENT_QUOTES
);
970 // Whitespace is normalized during attribute decoding,
971 // so if we've been passed non-spaces we must encode them
972 // ahead of time or they won't be preserved.
973 $encValue = strtr( $encValue, array(
983 * Encode an attribute value for HTML tags, with extra armoring
984 * against further wiki processing.
985 * @param $text String
986 * @return HTML-encoded text fragment
988 static function safeEncodeAttribute( $text ) {
989 $encValue = Sanitizer
::encodeAttribute( $text );
991 # Templates and links may be expanded in later parsing,
992 # creating invalid or dangerous output. Suppress this.
993 $encValue = strtr( $encValue, array(
994 '<' => '<', // This should never happen,
995 '>' => '>', // we've received invalid input
996 '"' => '"', // which should have been escaped.
999 "''" => '''',
1000 'ISBN' => 'ISBN',
1002 'PMID' => 'PMID',
1008 $encValue = preg_replace_callback(
1009 '/(' . wfUrlProtocols() . ')/',
1010 array( 'Sanitizer', 'armorLinksCallback' ),
1016 * Given a value, escape it so that it can be used in an id attribute and
1017 * return it. This will use HTML5 validation if $wgExperimentalHtmlIds is
1018 * true, allowing anything but ASCII whitespace. Otherwise it will use
1019 * HTML 4 rules, which means a narrow subset of ASCII, with bad characters
1020 * escaped with lots of dots.
1022 * To ensure we don't have to bother escaping anything, we also strip ', ",
1023 * & even if $wgExperimentalIds is true. TODO: Is this the best tactic?
1024 * We also strip # because it upsets IE, and % because it could be
1025 * ambiguous if it's part of something that looks like a percent escape
1026 * (which don't work reliably in fragments cross-browser).
1028 * @see http://www.w3.org/TR/html401/types.html#type-name Valid characters
1031 * @see http://www.w3.org/TR/html401/struct/links.html#h-12.2.3 Anchors with the id attribute
1032 * @see http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-id-attribute
1033 * HTML5 definition of id attribute
1035 * @param $id String: id to escape
1036 * @param $options Mixed: string or array of strings (default is array()):
1037 * 'noninitial': This is a non-initial fragment of an id, not a full id,
1038 * so don't pay attention if the first character isn't valid at the
1039 * beginning of an id. Only matters if $wgExperimentalHtmlIds is
1041 * 'legacy': Behave the way the old HTML 4-based ID escaping worked even
1042 * if $wgExperimentalHtmlIds is used, so we can generate extra
1043 * anchors and links won't break.
1046 static function escapeId( $id, $options = array() ) {
1047 global $wgHtml5, $wgExperimentalHtmlIds;
1048 $options = (array)$options;
1050 if ( $wgHtml5 && $wgExperimentalHtmlIds && !in_array( 'legacy', $options ) ) {
1051 $id = Sanitizer
::decodeCharReferences( $id );
1052 $id = preg_replace( '/[ \t\n\r\f_\'"&#%]+/', '_', $id );
1053 $id = trim( $id, '_' );
1055 # Must have been all whitespace to start with.
1062 # HTML4-style escaping
1063 static $replace = array(
1068 $id = urlencode( Sanitizer
::decodeCharReferences( strtr( $id, ' ', '_' ) ) );
1069 $id = str_replace( array_keys( $replace ), array_values( $replace ), $id );
1071 if ( !preg_match( '/^[a-zA-Z]/', $id )
1072 && !in_array( 'noninitial', $options ) ) {
1073 // Initial character must be a letter!
1080 * Given a value, escape it so that it can be used as a CSS class and
1083 * @todo For extra validity, input should be validated UTF-8.
1085 * @see http://www.w3.org/TR/CSS21/syndata.html Valid characters/format
1087 * @param $class String
1090 static function escapeClass( $class ) {
1091 // Convert ugly stuff to underscores and kill underscores in ugly places
1092 return rtrim(preg_replace(
1093 array('/(^[0-9\\-])|[\\x00-\\x20!"#$%&\'()*+,.\\/:;<=>?@[\\]^`{|}~]|\\xC2\\xA0/','/_+/'),
1099 * Given HTML input, escape with htmlspecialchars but un-escape entites.
1100 * This allows (generally harmless) entities like   to survive.
1102 * @param $html String to escape
1103 * @return String: escaped input
1105 static function escapeHtmlAllowEntities( $html ) {
1106 $html = Sanitizer
::decodeCharReferences( $html );
1107 # It seems wise to escape ' as well as ", as a matter of course. Can't
1109 $html = htmlspecialchars( $html, ENT_QUOTES
);
1114 * Regex replace callback for armoring links against further processing.
1115 * @param $matches Array
1118 private static function armorLinksCallback( $matches ) {
1119 return str_replace( ':', ':', $matches[1] );
1123 * Return an associative array of attribute names and values from
1124 * a partial tag string. Attribute names are forces to lowercase,
1125 * character references are decoded to UTF-8 text.
1127 * @param $text String
1130 public static function decodeTagAttributes( $text ) {
1131 if( trim( $text ) == '' ) {
1137 if( !preg_match_all(
1138 self
::getAttribsRegex(),
1141 PREG_SET_ORDER
) ) {
1145 foreach( $pairs as $set ) {
1146 $attribute = strtolower( $set[1] );
1147 $value = Sanitizer
::getTagAttributeCallback( $set );
1149 // Normalize whitespace
1150 $value = preg_replace( '/[\t\r\n ]+/', ' ', $value );
1151 $value = trim( $value );
1153 // Decode character references
1154 $attribs[$attribute] = Sanitizer
::decodeCharReferences( $value );
1160 * Pick the appropriate attribute value from a match set from the
1161 * attribs regex matches.
1166 private static function getTagAttributeCallback( $set ) {
1167 if( isset( $set[6] ) ) {
1168 # Illegal #XXXXXX color with no quotes.
1170 } elseif( isset( $set[5] ) ) {
1173 } elseif( isset( $set[4] ) ) {
1176 } elseif( isset( $set[3] ) ) {
1179 } elseif( !isset( $set[2] ) ) {
1180 # In XHTML, attributes must have a value.
1181 # For 'reduced' form, return explicitly the attribute name here.
1184 throw new MWException( "Tag conditions not met. This should never happen and is a bug." );
1189 * Normalize whitespace and character references in an XML source-
1190 * encoded text for an attribute value.
1192 * See http://www.w3.org/TR/REC-xml/#AVNormalize for background,
1193 * but note that we're not returning the value, but are returning
1194 * XML source fragments that will be slapped into output.
1196 * @param $text String
1199 private static function normalizeAttributeValue( $text ) {
1200 return str_replace( '"', '"',
1201 self
::normalizeWhitespace(
1202 Sanitizer
::normalizeCharReferences( $text ) ) );
1206 * @param $text string
1209 private static function normalizeWhitespace( $text ) {
1210 return preg_replace(
1211 '/\r\n|[\x20\x0d\x0a\x09]/',
1217 * Normalizes whitespace in a section name, such as might be returned
1218 * by Parser::stripSectionName(), for use in the id's that are used for
1221 * @param $section String
1224 static function normalizeSectionNameWhitespace( $section ) {
1225 return trim( preg_replace( '/[ _]+/', ' ', $section ) );
1229 * Ensure that any entities and character references are legal
1230 * for XML and XHTML specifically. Any stray bits will be
1231 * &-escaped to result in a valid text fragment.
1233 * a. named char refs can only be < > & ", others are
1234 * numericized (this way we're well-formed even without a DTD)
1235 * b. any numeric char refs must be legal chars, not invalid or forbidden
1236 * c. use &#x, not &#X
1237 * d. fix or reject non-valid attributes
1239 * @param $text String
1243 static function normalizeCharReferences( $text ) {
1244 return preg_replace_callback(
1245 self
::CHAR_REFS_REGEX
,
1246 array( 'Sanitizer', 'normalizeCharReferencesCallback' ),
1250 * @param $matches String
1253 static function normalizeCharReferencesCallback( $matches ) {
1255 if( $matches[1] != '' ) {
1256 $ret = Sanitizer
::normalizeEntity( $matches[1] );
1257 } elseif( $matches[2] != '' ) {
1258 $ret = Sanitizer
::decCharReference( $matches[2] );
1259 } elseif( $matches[3] != '' ) {
1260 $ret = Sanitizer
::hexCharReference( $matches[3] );
1262 if( is_null( $ret ) ) {
1263 return htmlspecialchars( $matches[0] );
1270 * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1271 * return the equivalent numeric entity reference (except for the core <
1272 * > & "). If the entity is a MediaWiki-specific alias, returns
1273 * the HTML equivalent. Otherwise, returns HTML-escaped text of
1274 * pseudo-entity source (eg &foo;)
1276 * @param $name String
1279 static function normalizeEntity( $name ) {
1280 if ( isset( self
::$htmlEntityAliases[$name] ) ) {
1281 return '&' . self
::$htmlEntityAliases[$name] . ';';
1282 } elseif ( in_array( $name,
1283 array( 'lt', 'gt', 'amp', 'quot' ) ) ) {
1285 } elseif ( isset( self
::$htmlEntities[$name] ) ) {
1286 return '&#' . self
::$htmlEntities[$name] . ';';
1288 return "&$name;";
1294 * @return null|string
1296 static function decCharReference( $codepoint ) {
1297 $point = intval( $codepoint );
1298 if( Sanitizer
::validateCodepoint( $point ) ) {
1299 return sprintf( '&#%d;', $point );
1307 * @return null|string
1309 static function hexCharReference( $codepoint ) {
1310 $point = hexdec( $codepoint );
1311 if( Sanitizer
::validateCodepoint( $point ) ) {
1312 return sprintf( '&#x%x;', $point );
1319 * Returns true if a given Unicode codepoint is a valid character in XML.
1320 * @param $codepoint Integer
1323 private static function validateCodepoint( $codepoint ) {
1324 return ($codepoint == 0x09)
1325 ||
($codepoint == 0x0a)
1326 ||
($codepoint == 0x0d)
1327 ||
($codepoint >= 0x20 && $codepoint <= 0xd7ff)
1328 ||
($codepoint >= 0xe000 && $codepoint <= 0xfffd)
1329 ||
($codepoint >= 0x10000 && $codepoint <= 0x10ffff);
1333 * Decode any character references, numeric or named entities,
1334 * in the text and return a UTF-8 string.
1336 * @param $text String
1339 public static function decodeCharReferences( $text ) {
1340 return preg_replace_callback(
1341 self
::CHAR_REFS_REGEX
,
1342 array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1347 * Decode any character references, numeric or named entities,
1348 * in the next and normalize the resulting string. (bug 14952)
1350 * This is useful for page titles, not for text to be displayed,
1351 * MediaWiki allows HTML entities to escape normalization as a feature.
1353 * @param $text String (already normalized, containing entities)
1354 * @return String (still normalized, without entities)
1356 public static function decodeCharReferencesAndNormalize( $text ) {
1358 $text = preg_replace_callback(
1359 self
::CHAR_REFS_REGEX
,
1360 array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1361 $text, /* limit */ -1, $count );
1364 return $wgContLang->normalize( $text );
1371 * @param $matches String
1374 static function decodeCharReferencesCallback( $matches ) {
1375 if( $matches[1] != '' ) {
1376 return Sanitizer
::decodeEntity( $matches[1] );
1377 } elseif( $matches[2] != '' ) {
1378 return Sanitizer
::decodeChar( intval( $matches[2] ) );
1379 } elseif( $matches[3] != '' ) {
1380 return Sanitizer
::decodeChar( hexdec( $matches[3] ) );
1382 # Last case should be an ampersand by itself
1387 * Return UTF-8 string for a codepoint if that is a valid
1388 * character reference, otherwise U+FFFD REPLACEMENT CHARACTER.
1389 * @param $codepoint Integer
1393 static function decodeChar( $codepoint ) {
1394 if( Sanitizer
::validateCodepoint( $codepoint ) ) {
1395 return codepointToUtf8( $codepoint );
1397 return UTF8_REPLACEMENT
;
1402 * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1403 * return the UTF-8 encoding of that character. Otherwise, returns
1404 * pseudo-entity source (eg &foo;)
1406 * @param $name String
1409 static function decodeEntity( $name ) {
1410 if ( isset( self
::$htmlEntityAliases[$name] ) ) {
1411 $name = self
::$htmlEntityAliases[$name];
1413 if( isset( self
::$htmlEntities[$name] ) ) {
1414 return codepointToUtf8( self
::$htmlEntities[$name] );
1421 * Fetch the whitelist of acceptable attributes for a given element name.
1423 * @param $element String
1426 static function attributeWhitelist( $element ) {
1428 if( !isset( $list ) ) {
1429 $list = Sanitizer
::setupAttributeWhitelist();
1431 return isset( $list[$element] )
1437 * Foreach array key (an allowed HTML element), return an array
1438 * of allowed attributes
1441 static function setupAttributeWhitelist() {
1442 global $wgAllowRdfaAttributes, $wgHtml5, $wgAllowMicrodataAttributes;
1444 $common = array( 'id', 'class', 'lang', 'dir', 'title', 'style' );
1446 if ( $wgAllowRdfaAttributes ) {
1447 #RDFa attributes as specified in section 9 of http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014
1448 $common = array_merge( $common, array(
1449 'about', 'property', 'resource', 'datatype', 'typeof',
1453 if ( $wgHtml5 && $wgAllowMicrodataAttributes ) {
1454 # add HTML5 microdata tages as pecified by http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#the-microdata-model
1455 $common = array_merge( $common, array(
1456 'itemid', 'itemprop', 'itemref', 'itemscope', 'itemtype'
1460 $block = array_merge( $common, array( 'align' ) );
1461 $tablealign = array( 'align', 'char', 'charoff', 'valign' );
1462 $tablecell = array( 'abbr',
1468 'nowrap', # deprecated
1469 'width', # deprecated
1470 'height', # deprecated
1471 'bgcolor' # deprecated
1474 # Numbers refer to sections in HTML 4.01 standard describing the element.
1475 # See: http://www.w3.org/TR/html4/
1476 $whitelist = array (
1479 'center' => $common, # deprecated
1480 'span' => $block, # ??
1498 'strong' => $common,
1509 'blockquote' => array_merge( $common, array( 'cite' ) ),
1520 'br' => array( 'id', 'class', 'title', 'style', 'clear' ),
1523 'pre' => array_merge( $common, array( 'width' ) ),
1526 'ins' => array_merge( $common, array( 'cite', 'datetime' ) ),
1527 'del' => array_merge( $common, array( 'cite', 'datetime' ) ),
1530 'ul' => array_merge( $common, array( 'type' ) ),
1531 'ol' => array_merge( $common, array( 'type', 'start' ) ),
1532 'li' => array_merge( $common, array( 'type', 'value' ) ),
1540 'table' => array_merge( $common,
1541 array( 'summary', 'width', 'border', 'frame',
1542 'rules', 'cellspacing', 'cellpadding',
1547 'caption' => array_merge( $common, array( 'align' ) ),
1550 'thead' => array_merge( $common, $tablealign ),
1551 'tfoot' => array_merge( $common, $tablealign ),
1552 'tbody' => array_merge( $common, $tablealign ),
1555 'colgroup' => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1556 'col' => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1559 'tr' => array_merge( $common, array( 'bgcolor' ), $tablealign ),
1562 'td' => array_merge( $common, $tablecell, $tablealign ),
1563 'th' => array_merge( $common, $tablecell, $tablealign ),
1565 # 12.2 # NOTE: <a> is not allowed directly, but the attrib whitelist is used from the Parser object
1566 'a' => array_merge( $common, array( 'href', 'rel', 'rev' ) ), # rel/rev esp. for RDFa
1569 # Not usually allowed, but may be used for extension-style hooks
1570 # such as <math> when it is rasterized, or if $wgAllowImageTag is
1572 'img' => array_merge( $common, array( 'alt', 'src', 'width', 'height' ) ),
1580 'strike' => $common,
1585 'font' => array_merge( $common, array( 'size', 'color', 'face' ) ),
1589 'hr' => array_merge( $common, array( 'noshade', 'size', 'width' ) ),
1591 # XHTML Ruby annotation text module, simple ruby only.
1592 # http://www.w3c.org/TR/ruby/
1597 'rt' => $common, #array_merge( $common, array( 'rbspan' ) ),
1600 # MathML root element, where used for extensions
1601 # 'title' may not be 100% valid here; it's XHTML
1602 # http://www.w3.org/TR/REC-MathML/
1603 'math' => array( 'class', 'style', 'id', 'title' ),
1609 * Take a fragment of (potentially invalid) HTML and return
1610 * a version with any tags removed, encoded as plain text.
1612 * Warning: this return value must be further escaped for literal
1613 * inclusion in HTML output as of 1.10!
1615 * @param $text String: HTML fragment
1618 static function stripAllTags( $text ) {
1620 $text = StringUtils
::delimiterReplace( '<', '>', '', $text );
1622 # Normalize &entities and whitespace
1623 $text = self
::decodeCharReferences( $text );
1624 $text = self
::normalizeWhitespace( $text );
1630 * Hack up a private DOCTYPE with HTML's standard entity declarations.
1631 * PHP 4 seemed to know these if you gave it an HTML doctype, but
1634 * Use for passing XHTML fragments to PHP's XML parsing functions
1638 static function hackDocType() {
1639 $out = "<!DOCTYPE html [\n";
1640 foreach( self
::$htmlEntities as $entity => $codepoint ) {
1641 $out .= "<!ENTITY $entity \"&#$codepoint;\">";
1648 * @param $url string
1649 * @return mixed|string
1651 static function cleanUrl( $url ) {
1652 # Normalize any HTML entities in input. They will be
1653 # re-escaped by makeExternalLink().
1654 $url = Sanitizer
::decodeCharReferences( $url );
1656 # Escape any control characters introduced by the above step
1657 $url = preg_replace_callback( '/[\][<>"\\x00-\\x20\\x7F\|]/',
1658 array( __CLASS__
, 'cleanUrlCallback' ), $url );
1660 # Validate hostname portion
1662 if( preg_match( '!^([^:]+:)(//[^/]+)?(.*)$!iD', $url, $matches ) ) {
1663 list( /* $whole */, $protocol, $host, $rest ) = $matches;
1665 // Characters that will be ignored in IDNs.
1666 // http://tools.ietf.org/html/3454#section-3.1
1667 // Strip them before further processing so blacklists and such work.
1669 \\s| # general whitespace
1670 \xc2\xad| # 00ad SOFT HYPHEN
1671 \xe1\xa0\x86| # 1806 MONGOLIAN TODO SOFT HYPHEN
1672 \xe2\x80\x8b| # 200b ZERO WIDTH SPACE
1673 \xe2\x81\xa0| # 2060 WORD JOINER
1674 \xef\xbb\xbf| # feff ZERO WIDTH NO-BREAK SPACE
1675 \xcd\x8f| # 034f COMBINING GRAPHEME JOINER
1676 \xe1\xa0\x8b| # 180b MONGOLIAN FREE VARIATION SELECTOR ONE
1677 \xe1\xa0\x8c| # 180c MONGOLIAN FREE VARIATION SELECTOR TWO
1678 \xe1\xa0\x8d| # 180d MONGOLIAN FREE VARIATION SELECTOR THREE
1679 \xe2\x80\x8c| # 200c ZERO WIDTH NON-JOINER
1680 \xe2\x80\x8d| # 200d ZERO WIDTH JOINER
1681 [\xef\xb8\x80-\xef\xb8\x8f] # fe00-fe00f VARIATION SELECTOR-1-16
1684 $host = preg_replace( $strip, '', $host );
1686 // @todo FIXME: Validate hostnames here
1688 return $protocol . $host . $rest;
1695 * @param $matches array
1698 static function cleanUrlCallback( $matches ) {
1699 return urlencode( $matches[0] );
1703 * Does a string look like an e-mail address?
1705 * This validates an email address using an HTML5 specification found at:
1706 * http://www.whatwg.org/specs/web-apps/current-work/multipage/states-of-the-type-attribute.html#valid-e-mail-address
1707 * Which as of 2011-01-24 says:
1709 * A valid e-mail address is a string that matches the ABNF production
1710 * 1*( atext / "." ) "@" ldh-str *( "." ldh-str ) where atext is defined
1711 * in RFC 5322 section 3.2.3, and ldh-str is defined in RFC 1034 section
1714 * This function is an implementation of the specification as requested in
1717 * Client-side forms will use the same standard validation rules via JS or
1718 * HTML 5 validation; additional restrictions can be enforced server-side
1719 * by extensions via the 'isValidEmailAddr' hook.
1721 * Note that this validation doesn't 100% match RFC 2822, but is believed
1722 * to be liberal enough for wide use. Some invalid addresses will still
1723 * pass validation here.
1727 * @param $addr String E-mail address
1730 public static function validateEmail( $addr ) {
1732 if( !wfRunHooks( 'isValidEmailAddr', array( $addr, &$result ) ) ) {
1736 // Please note strings below are enclosed in brackets [], this make the
1737 // hyphen "-" a range indicator. Hence it is double backslashed below.
1739 $rfc5322_atext = "a-z0-9!#$%&'*+\\-\/=?^_`{|}~" ;
1740 $rfc1034_ldh_str = "a-z0-9\\-" ;
1742 $HTML5_email_regexp = "/
1744 [$rfc5322_atext\\.]+ # user part which is liberal :p
1746 [$rfc1034_ldh_str]+ # First domain part
1747 (\\.[$rfc1034_ldh_str]+)* # Following part prefixed with a dot
1749 /ix" ; // case Insensitive, eXtended
1751 return (bool) preg_match( $HTML5_email_regexp, $addr );