includes/Sanitizer.php

   1 <?php
   2 /**
   3  * HTML sanitizer for %MediaWiki.
   4  *
   5  * Copyright © 2002-2005 Brion Vibber <brion@pobox.com> et al
   6  * http://www.mediawiki.org/
   7  *
   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.
  12  *
  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.
  17  *
  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
  22  *
  23  * @file
  24  * @ingroup Parser
  25  */
  26
  27 /**
  28  * HTML sanitizer for MediaWiki
  29  * @ingroup Parser
  30  */
  31 class Sanitizer {
  32         /**
  33          * Regular expression to match various types of character references in
  34          * Sanitizer::normalizeCharReferences and Sanitizer::decodeCharReferences
  35          */
  36         const CHAR_REFS_REGEX =
  37                 '/&([A-Za-z0-9\x80-\xff]+);
  38                  |&\#([0-9]+);
  39                  |&\#[xX]([0-9A-Fa-f]+);
  40                  |(&)/x';
  41
  42         /**
  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
  49          */
  50         const EVIL_URI_PATTERN = '!(^|\s|\*/\s*)(javascript|vbscript)([^\w]|$)!i';
  51         const XMLNS_ATTRIBUTE_PATTERN = "/^xmlns:[:A-Z_a-z-.0-9]+$/";
  52
  53         /**
  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 &apos; which is only defined starting in XHTML1.
  57          */
  58         private static $htmlEntities = array(
  59                 'Aacute'   => 193,
  60                 'aacute'   => 225,
  61                 'Acirc'    => 194,
  62                 'acirc'    => 226,
  63                 'acute'    => 180,
  64                 'AElig'    => 198,
  65                 'aelig'    => 230,
  66                 'Agrave'   => 192,
  67                 'agrave'   => 224,
  68                 'alefsym'  => 8501,
  69                 'Alpha'    => 913,
  70                 'alpha'    => 945,
  71                 'amp'      => 38,
  72                 'and'      => 8743,
  73                 'ang'      => 8736,
  74                 'apos'     => 39, // New in XHTML & HTML 5; avoid in output for compatibility with IE.
  75                 'Aring'    => 197,
  76                 'aring'    => 229,
  77                 'asymp'    => 8776,
  78                 'Atilde'   => 195,
  79                 'atilde'   => 227,
  80                 'Auml'     => 196,
  81                 'auml'     => 228,
  82                 'bdquo'    => 8222,
  83                 'Beta'     => 914,
  84                 'beta'     => 946,
  85                 'brvbar'   => 166,
  86                 'bull'     => 8226,
  87                 'cap'      => 8745,
  88                 'Ccedil'   => 199,
  89                 'ccedil'   => 231,
  90                 'cedil'    => 184,
  91                 'cent'     => 162,
  92                 'Chi'      => 935,
  93                 'chi'      => 967,
  94                 'circ'     => 710,
  95                 'clubs'    => 9827,
  96                 'cong'     => 8773,
  97                 'copy'     => 169,
  98                 'crarr'    => 8629,
  99                 'cup'      => 8746,
 100                 'curren'   => 164,
 101                 'dagger'   => 8224,
 102                 'Dagger'   => 8225,
 103                 'darr'     => 8595,
 104                 'dArr'     => 8659,
 105                 'deg'      => 176,
 106                 'Delta'    => 916,
 107                 'delta'    => 948,
 108                 'diams'    => 9830,
 109                 'divide'   => 247,
 110                 'Eacute'   => 201,
 111                 'eacute'   => 233,
 112                 'Ecirc'    => 202,
 113                 'ecirc'    => 234,
 114                 'Egrave'   => 200,
 115                 'egrave'   => 232,
 116                 'empty'    => 8709,
 117                 'emsp'     => 8195,
 118                 'ensp'     => 8194,
 119                 'Epsilon'  => 917,
 120                 'epsilon'  => 949,
 121                 'equiv'    => 8801,
 122                 'Eta'      => 919,
 123                 'eta'      => 951,
 124                 'ETH'      => 208,
 125                 'eth'      => 240,
 126                 'Euml'     => 203,
 127                 'euml'     => 235,
 128                 'euro'     => 8364,
 129                 'exist'    => 8707,
 130                 'fnof'     => 402,
 131                 'forall'   => 8704,
 132                 'frac12'   => 189,
 133                 'frac14'   => 188,
 134                 'frac34'   => 190,
 135                 'frasl'    => 8260,
 136                 'Gamma'    => 915,
 137                 'gamma'    => 947,
 138                 'ge'       => 8805,
 139                 'gt'       => 62,
 140                 'harr'     => 8596,
 141                 'hArr'     => 8660,
 142                 'hearts'   => 9829,
 143                 'hellip'   => 8230,
 144                 'Iacute'   => 205,
 145                 'iacute'   => 237,
 146                 'Icirc'    => 206,
 147                 'icirc'    => 238,
 148                 'iexcl'    => 161,
 149                 'Igrave'   => 204,
 150                 'igrave'   => 236,
 151                 'image'    => 8465,
 152                 'infin'    => 8734,
 153                 'int'      => 8747,
 154                 'Iota'     => 921,
 155                 'iota'     => 953,
 156                 'iquest'   => 191,
 157                 'isin'     => 8712,
 158                 'Iuml'     => 207,
 159                 'iuml'     => 239,
 160                 'Kappa'    => 922,
 161                 'kappa'    => 954,
 162                 'Lambda'   => 923,
 163                 'lambda'   => 955,
 164                 'lang'     => 9001,
 165                 'laquo'    => 171,
 166                 'larr'     => 8592,
 167                 'lArr'     => 8656,
 168                 'lceil'    => 8968,
 169                 'ldquo'    => 8220,
 170                 'le'       => 8804,
 171                 'lfloor'   => 8970,
 172                 'lowast'   => 8727,
 173                 'loz'      => 9674,
 174                 'lrm'      => 8206,
 175                 'lsaquo'   => 8249,
 176                 'lsquo'    => 8216,
 177                 'lt'       => 60,
 178                 'macr'     => 175,
 179                 'mdash'    => 8212,
 180                 'micro'    => 181,
 181                 'middot'   => 183,
 182                 'minus'    => 8722,
 183                 'Mu'       => 924,
 184                 'mu'       => 956,
 185                 'nabla'    => 8711,
 186                 'nbsp'     => 160,
 187                 'ndash'    => 8211,
 188                 'ne'       => 8800,
 189                 'ni'       => 8715,
 190                 'not'      => 172,
 191                 'notin'    => 8713,
 192                 'nsub'     => 8836,
 193                 'Ntilde'   => 209,
 194                 'ntilde'   => 241,
 195                 'Nu'       => 925,
 196                 'nu'       => 957,
 197                 'Oacute'   => 211,
 198                 'oacute'   => 243,
 199                 'Ocirc'    => 212,
 200                 'ocirc'    => 244,
 201                 'OElig'    => 338,
 202                 'oelig'    => 339,
 203                 'Ograve'   => 210,
 204                 'ograve'   => 242,
 205                 'oline'    => 8254,
 206                 'Omega'    => 937,
 207                 'omega'    => 969,
 208                 'Omicron'  => 927,
 209                 'omicron'  => 959,
 210                 'oplus'    => 8853,
 211                 'or'       => 8744,
 212                 'ordf'     => 170,
 213                 'ordm'     => 186,
 214                 'Oslash'   => 216,
 215                 'oslash'   => 248,
 216                 'Otilde'   => 213,
 217                 'otilde'   => 245,
 218                 'otimes'   => 8855,
 219                 'Ouml'     => 214,
 220                 'ouml'     => 246,
 221                 'para'     => 182,
 222                 'part'     => 8706,
 223                 'permil'   => 8240,
 224                 'perp'     => 8869,
 225                 'Phi'      => 934,
 226                 'phi'      => 966,
 227                 'Pi'       => 928,
 228                 'pi'       => 960,
 229                 'piv'      => 982,
 230                 'plusmn'   => 177,
 231                 'pound'    => 163,
 232                 'prime'    => 8242,
 233                 'Prime'    => 8243,
 234                 'prod'     => 8719,
 235                 'prop'     => 8733,
 236                 'Psi'      => 936,
 237                 'psi'      => 968,
 238                 'quot'     => 34,
 239                 'radic'    => 8730,
 240                 'rang'     => 9002,
 241                 'raquo'    => 187,
 242                 'rarr'     => 8594,
 243                 'rArr'     => 8658,
 244                 'rceil'    => 8969,
 245                 'rdquo'    => 8221,
 246                 'real'     => 8476,
 247                 'reg'      => 174,
 248                 'rfloor'   => 8971,
 249                 'Rho'      => 929,
 250                 'rho'      => 961,
 251                 'rlm'      => 8207,
 252                 'rsaquo'   => 8250,
 253                 'rsquo'    => 8217,
 254                 'sbquo'    => 8218,
 255                 'Scaron'   => 352,
 256                 'scaron'   => 353,
 257                 'sdot'     => 8901,
 258                 'sect'     => 167,
 259                 'shy'      => 173,
 260                 'Sigma'    => 931,
 261                 'sigma'    => 963,
 262                 'sigmaf'   => 962,
 263                 'sim'      => 8764,
 264                 'spades'   => 9824,
 265                 'sub'      => 8834,
 266                 'sube'     => 8838,
 267                 'sum'      => 8721,
 268                 'sup'      => 8835,
 269                 'sup1'     => 185,
 270                 'sup2'     => 178,
 271                 'sup3'     => 179,
 272                 'supe'     => 8839,
 273                 'szlig'    => 223,
 274                 'Tau'      => 932,
 275                 'tau'      => 964,
 276                 'there4'   => 8756,
 277                 'Theta'    => 920,
 278                 'theta'    => 952,
 279                 'thetasym' => 977,
 280                 'thinsp'   => 8201,
 281                 'THORN'    => 222,
 282                 'thorn'    => 254,
 283                 'tilde'    => 732,
 284                 'times'    => 215,
 285                 'trade'    => 8482,
 286                 'Uacute'   => 218,
 287                 'uacute'   => 250,
 288                 'uarr'     => 8593,
 289                 'uArr'     => 8657,
 290                 'Ucirc'    => 219,
 291                 'ucirc'    => 251,
 292                 'Ugrave'   => 217,
 293                 'ugrave'   => 249,
 294                 'uml'      => 168,
 295                 'upsih'    => 978,
 296                 'Upsilon'  => 933,
 297                 'upsilon'  => 965,
 298                 'Uuml'     => 220,
 299                 'uuml'     => 252,
 300                 'weierp'   => 8472,
 301                 'Xi'       => 926,
 302                 'xi'       => 958,
 303                 'Yacute'   => 221,
 304                 'yacute'   => 253,
 305                 'yen'      => 165,
 306                 'Yuml'     => 376,
 307                 'yuml'     => 255,
 308                 'Zeta'     => 918,
 309                 'zeta'     => 950,
 310                 'zwj'      => 8205,
 311                 'zwnj'     => 8204
 312         );
 313
 314         /**
 315          * Character entity aliases accepted by MediaWiki
 316          */
 317         private static $htmlEntityAliases = array(
 318                 'רלמ' => 'rlm',
 319                 'رلم' => 'rlm',
 320         );
 321
 322         /**
 323          * Lazy-initialised attributes regex, see getAttribsRegex()
 324          */
 325         private static $attribsRegex;
 326
 327         /**
 328          * Regular expression to match HTML/XML attribute pairs within a tag.
 329          * Allows some... latitude.
 330          * Used in Sanitizer::fixTagAttributes and Sanitizer::decodeTagAttributes
 331          */
 332         static function getAttribsRegex() {
 333                 if ( self::$attribsRegex === null ) {
 334                         $attribFirst = '[:A-Z_a-z0-9]';
 335                         $attrib = '[:A-Z_a-z-.0-9]';
 336                         $space = '[\x09\x0a\x0d\x20]';
 337                         self::$attribsRegex =
 338                                 "/(?:^|$space)({$attribFirst}{$attrib}*)
 339                                   ($space*=$space*
 340                                         (?:
 341                                          # The attribute value: quoted or alone
 342                                           \"([^<\"]*)\"
 343                                          | '([^<']*)'
 344                                          |  ([a-zA-Z0-9!#$%&()*,\\-.\\/:;<>?@[\\]^_`{|}~]+)
 345                                          |  (\#[0-9a-fA-F]+) # Technically wrong, but lots of
 346                                                                                  # colors are specified like this.
 347                                                                                  # We'll be normalizing it.
 348                                         )
 349                                 )?(?=$space|\$)/sx";
 350                 }
 351                 return self::$attribsRegex;
 352         }
 353
 354         /**
 355          * Cleans up HTML, removes dangerous tags and attributes, and
 356          * removes HTML comments
 357          * @private
 358          * @param string $text
 359          * @param callable $processCallback Callback to do any variable or parameter
 360          *   replacements in HTML attribute values
 361          * @param array $args Arguments for the processing callback
 362          * @param array $extratags For any extra tags to include
 363          * @param array $removetags For any tags (default or extra) to exclude
 364          * @return string
 365          */
 366         static function removeHTMLtags( $text, $processCallback = null,
 367                 $args = array(), $extratags = array(), $removetags = array()
 368         ) {
 369                 global $wgUseTidy, $wgAllowMicrodataAttributes, $wgAllowImageTag;
 370
 371                 static $htmlpairsStatic, $htmlsingle, $htmlsingleonly, $htmlnest, $tabletags,
 372                         $htmllist, $listtags, $htmlsingleallowed, $htmlelementsStatic, $staticInitialised;
 373
 374                 wfProfileIn( __METHOD__ );
 375
 376                 // Base our staticInitialised variable off of the global config state so that if the globals
 377                 // are changed (like in the screwed up test system) we will re-initialise the settings.
 378                 $globalContext = implode( '-', compact( 'wgAllowMicrodataAttributes', 'wgAllowImageTag' ) );
 379                 if ( !$staticInitialised || $staticInitialised != $globalContext ) {
 380
 381                         $htmlpairsStatic = array( # Tags that must be closed
 382                                 'b', 'bdi', 'del', 'i', 'ins', 'u', 'font', 'big', 'small', 'sub', 'sup', 'h1',
 383                                 'h2', 'h3', 'h4', 'h5', 'h6', 'cite', 'code', 'em', 's',
 384                                 'strike', 'strong', 'tt', 'var', 'div', 'center',
 385                                 'blockquote', 'ol', 'ul', 'dl', 'table', 'caption', 'pre',
 386                                 'ruby', 'rt', 'rb', 'rp', 'p', 'span', 'abbr', 'dfn',
 387                                 'kbd', 'samp', 'data', 'time', 'mark'
 388                         );
 389                         $htmlsingle = array(
 390                                 'br', 'wbr', 'hr', 'li', 'dt', 'dd'
 391                         );
 392                         $htmlsingleonly = array( # Elements that cannot have close tags
 393                                 'br', 'wbr', 'hr'
 394                         );
 395                         if ( $wgAllowMicrodataAttributes ) {
 396                                 $htmlsingle[] = $htmlsingleonly[] = 'meta';
 397                                 $htmlsingle[] = $htmlsingleonly[] = 'link';
 398                         }
 399                         $htmlnest = array( # Tags that can be nested--??
 400                                 'table', 'tr', 'td', 'th', 'div', 'blockquote', 'ol', 'ul',
 401                                 'li', 'dl', 'dt', 'dd', 'font', 'big', 'small', 'sub', 'sup', 'span',
 402                                 'var', 'kbd', 'samp', 'em', 'strong', 'q', 'ruby', 'bdo'
 403                         );
 404                         $tabletags = array( # Can only appear inside table, we will close them
 405                                 'td', 'th', 'tr',
 406                         );
 407                         $htmllist = array( # Tags used by list
 408                                 'ul', 'ol',
 409                         );
 410                         $listtags = array( # Tags that can appear in a list
 411                                 'li',
 412                         );
 413
 414                         if ( $wgAllowImageTag ) {
 415                                 $htmlsingle[] = 'img';
 416                                 $htmlsingleonly[] = 'img';
 417                         }
 418
 419                         $htmlsingleallowed = array_unique( array_merge( $htmlsingle, $tabletags ) );
 420                         $htmlelementsStatic = array_unique( array_merge( $htmlsingle, $htmlpairsStatic, $htmlnest ) );
 421
 422                         # Convert them all to hashtables for faster lookup
 423                         $vars = array( 'htmlpairsStatic', 'htmlsingle', 'htmlsingleonly', 'htmlnest', 'tabletags',
 424                                 'htmllist', 'listtags', 'htmlsingleallowed', 'htmlelementsStatic' );
 425                         foreach ( $vars as $var ) {
 426                                 $$var = array_flip( $$var );
 427                         }
 428                         $staticInitialised = $globalContext;
 429                 }
 430                 # Populate $htmlpairs and $htmlelements with the $extratags and $removetags arrays
 431                 $extratags = array_flip( $extratags );
 432                 $removetags = array_flip( $removetags );
 433                 $htmlpairs = array_merge( $extratags, $htmlpairsStatic );
 434                 $htmlelements = array_diff_key( array_merge( $extratags, $htmlelementsStatic ), $removetags );
 435
 436                 # Remove HTML comments
 437                 $text = Sanitizer::removeHTMLcomments( $text );
 438                 $bits = explode( '<', $text );
 439                 $text = str_replace( '>', '&gt;', array_shift( $bits ) );
 440                 if ( !$wgUseTidy ) {
 441                         $tagstack = $tablestack = array();
 442                         foreach ( $bits as $x ) {
 443                                 $regs = array();
 444                                 # $slash: Does the current element start with a '/'?
 445                                 # $t: Current element name
 446                                 # $params: String between element name and >
 447                                 # $brace: Ending '>' or '/>'
 448                                 # $rest: Everything until the next element of $bits
 449                                 if ( preg_match( '!^(/?)([^\\s/>]+)([^>]*?)(/{0,1}>)([^<]*)$!', $x, $regs ) ) {
 450                                         list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
 451                                 } else {
 452                                         $slash = $t = $params = $brace = $rest = null;
 453                                 }
 454
 455                                 $badtag = false;
 456                                 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
 457                                         # Check our stack
 458                                         if ( $slash && isset( $htmlsingleonly[$t] ) ) {
 459                                                 $badtag = true;
 460                                         } elseif ( $slash ) {
 461                                                 # Closing a tag... is it the one we just opened?
 462                                                 $ot = @array_pop( $tagstack );
 463                                                 if ( $ot != $t ) {
 464                                                         if ( isset( $htmlsingleallowed[$ot] ) ) {
 465                                                                 # Pop all elements with an optional close tag
 466                                                                 # and see if we find a match below them
 467                                                                 $optstack = array();
 468                                                                 array_push( $optstack, $ot );
 469                                                                 wfSuppressWarnings();
 470                                                                 $ot = array_pop( $tagstack );
 471                                                                 wfRestoreWarnings();
 472                                                                 while ( $ot != $t && isset( $htmlsingleallowed[$ot] ) ) {
 473                                                                         array_push( $optstack, $ot );
 474                                                                         wfSuppressWarnings();
 475                                                                         $ot = array_pop( $tagstack );
 476                                                                         wfRestoreWarnings();
 477                                                                 }
 478                                                                 if ( $t != $ot ) {
 479                                                                         # No match. Push the optional elements back again
 480                                                                         $badtag = true;
 481                                                                         wfSuppressWarnings();
 482                                                                         $ot = array_pop( $optstack );
 483                                                                         wfRestoreWarnings();
 484                                                                         while ( $ot ) {
 485                                                                                 array_push( $tagstack, $ot );
 486                                                                                 wfSuppressWarnings();
 487                                                                                 $ot = array_pop( $optstack );
 488                                                                                 wfRestoreWarnings();
 489                                                                         }
 490                                                                 }
 491                                                         } else {
 492                                                                 @array_push( $tagstack, $ot );
 493                                                                 # <li> can be nested in <ul> or <ol>, skip those cases:
 494                                                                 if ( !isset( $htmllist[$ot] ) || !isset( $listtags[$t] ) ) {
 495                                                                         $badtag = true;
 496                                                                 }
 497                                                         }
 498                                                 } else {
 499                                                         if ( $t == 'table' ) {
 500                                                                 $tagstack = array_pop( $tablestack );
 501                                                         }
 502                                                 }
 503                                                 $newparams = '';
 504                                         } else {
 505                                                 # Keep track for later
 506                                                 if ( isset( $tabletags[$t] ) &&
 507                                                 !in_array( 'table', $tagstack ) ) {
 508                                                         $badtag = true;
 509                                                 } elseif ( in_array( $t, $tagstack ) &&
 510                                                 !isset( $htmlnest[$t] ) ) {
 511                                                         $badtag = true;
 512                                                 # Is it a self closed htmlpair ? (bug 5487)
 513                                                 } elseif ( $brace == '/>' &&
 514                                                 isset( $htmlpairs[$t] ) ) {
 515                                                         $badtag = true;
 516                                                 } elseif ( isset( $htmlsingleonly[$t] ) ) {
 517                                                         # Hack to force empty tag for unclosable elements
 518                                                         $brace = '/>';
 519                                                 } elseif ( isset( $htmlsingle[$t] ) ) {
 520                                                         # Hack to not close $htmlsingle tags
 521                                                         $brace = null;
 522                                                         # Still need to push this optionally-closed tag to
 523                                                         # the tag stack so that we can match end tags
 524                                                         # instead of marking them as bad.
 525                                                         array_push( $tagstack, $t );
 526                                                 } elseif ( isset( $tabletags[$t] )
 527                                                 && in_array( $t, $tagstack ) ) {
 528                                                         // New table tag but forgot to close the previous one
 529                                                         $text .= "</$t>";
 530                                                 } else {
 531                                                         if ( $t == 'table' ) {
 532                                                                 array_push( $tablestack, $tagstack );
 533                                                                 $tagstack = array();
 534                                                         }
 535                                                         array_push( $tagstack, $t );
 536                                                 }
 537
 538                                                 # Replace any variables or template parameters with
 539                                                 # plaintext results.
 540                                                 if ( is_callable( $processCallback ) ) {
 541                                                         call_user_func_array( $processCallback, array( &$params, $args ) );
 542                                                 }
 543
 544                                                 if ( !Sanitizer::validateTag( $params, $t ) ) {
 545                                                         $badtag = true;
 546                                                 }
 547
 548                                                 # Strip non-approved attributes from the tag
 549                                                 $newparams = Sanitizer::fixTagAttributes( $params, $t );
 550                                         }
 551                                         if ( !$badtag ) {
 552                                                 $rest = str_replace( '>', '&gt;', $rest );
 553                                                 $close = ( $brace == '/>' && !$slash ) ? ' /' : '';
 554                                                 $text .= "<$slash$t$newparams$close>$rest";
 555                                                 continue;
 556                                         }
 557                                 }
 558                                 $text .= '&lt;' . str_replace( '>', '&gt;', $x );
 559                         }
 560                         # Close off any remaining tags
 561                         while ( is_array( $tagstack ) && ( $t = array_pop( $tagstack ) ) ) {
 562                                 $text .= "</$t>\n";
 563                                 if ( $t == 'table' ) {
 564                                         $tagstack = array_pop( $tablestack );
 565                                 }
 566                         }
 567                 } else {
 568                         # this might be possible using tidy itself
 569                         foreach ( $bits as $x ) {
 570                                 preg_match( '/^(\\/?)(\\w+)([^>]*?)(\\/{0,1}>)([^<]*)$/',
 571                                 $x, $regs );
 572                                 @list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
 573                                 $badtag = false;
 574                                 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
 575                                         if ( is_callable( $processCallback ) ) {
 576                                                 call_user_func_array( $processCallback, array( &$params, $args ) );
 577                                         }
 578
 579                                         if ( !Sanitizer::validateTag( $params, $t ) ) {
 580                                                 $badtag = true;
 581                                         }
 582
 583                                         $newparams = Sanitizer::fixTagAttributes( $params, $t );
 584                                         if ( !$badtag ) {
 585                                                 $rest = str_replace( '>', '&gt;', $rest );
 586                                                 $text .= "<$slash$t$newparams$brace$rest";
 587                                                 continue;
 588                                         }
 589                                 }
 590                                 $text .= '&lt;' . str_replace( '>', '&gt;', $x );
 591                         }
 592                 }
 593                 wfProfileOut( __METHOD__ );
 594                 return $text;
 595         }
 596
 597         /**
 598          * Remove '<!--', '-->', and everything between.
 599          * To avoid leaving blank lines, when a comment is both preceded
 600          * and followed by a newline (ignoring spaces), trim leading and
 601          * trailing spaces and one of the newlines.
 602          *
 603          * @private
 604          * @param string $text
 605          * @return string
 606          */
 607         static function removeHTMLcomments( $text ) {
 608                 wfProfileIn( __METHOD__ );
 609                 while ( ( $start = strpos( $text, '<!--' ) ) !== false ) {
 610                         $end = strpos( $text, '-->', $start + 4 );
 611                         if ( $end === false ) {
 612                                 # Unterminated comment; bail out
 613                                 break;
 614                         }
 615
 616                         $end += 3;
 617
 618                         # Trim space and newline if the comment is both
 619                         # preceded and followed by a newline
 620                         $spaceStart = max( $start - 1, 0 );
 621                         $spaceLen = $end - $spaceStart;
 622                         while ( substr( $text, $spaceStart, 1 ) === ' ' && $spaceStart > 0 ) {
 623                                 $spaceStart--;
 624                                 $spaceLen++;
 625                         }
 626                         while ( substr( $text, $spaceStart + $spaceLen, 1 ) === ' ' ) {
 627                                 $spaceLen++;
 628                         }
 629                         if ( substr( $text, $spaceStart, 1 ) === "\n"
 630                                 && substr( $text, $spaceStart + $spaceLen, 1 ) === "\n" ) {
 631                                 # Remove the comment, leading and trailing
 632                                 # spaces, and leave only one newline.
 633                                 $text = substr_replace( $text, "\n", $spaceStart, $spaceLen + 1 );
 634                         }
 635                         else {
 636                                 # Remove just the comment.
 637                                 $text = substr_replace( $text, '', $start, $end - $start );
 638                         }
 639                 }
 640                 wfProfileOut( __METHOD__ );
 641                 return $text;
 642         }
 643
 644         /**
 645          * Takes attribute names and values for a tag and the tag name and
 646          * validates that the tag is allowed to be present.
 647          * This DOES NOT validate the attributes, nor does it validate the
 648          * tags themselves. This method only handles the special circumstances
 649          * where we may want to allow a tag within content but ONLY when it has
 650          * specific attributes set.
 651          *
 652          * @param string $params
 653          * @param string $element
 654          * @return bool
 655          */
 656         static function validateTag( $params, $element ) {
 657                 $params = Sanitizer::decodeTagAttributes( $params );
 658
 659                 if ( $element == 'meta' || $element == 'link' ) {
 660                         if ( !isset( $params['itemprop'] ) ) {
 661                                 // <meta> and <link> must have an itemprop="" otherwise they are not valid or safe in content
 662                                 return false;
 663                         }
 664                         if ( $element == 'meta' && !isset( $params['content'] ) ) {
 665                                 // <meta> must have a content="" for the itemprop
 666                                 return false;
 667                         }
 668                         if ( $element == 'link' && !isset( $params['href'] ) ) {
 669                                 // <link> must have an associated href=""
 670                                 return false;
 671                         }
 672                 }
 673
 674                 return true;
 675         }
 676
 677         /**
 678          * Take an array of attribute names and values and normalize or discard
 679          * illegal values for the given element type.
 680          *
 681          * - Discards attributes not on a whitelist for the given element
 682          * - Unsafe style attributes are discarded
 683          * - Invalid id attributes are re-encoded
 684          *
 685          * @param array $attribs
 686          * @param string $element
 687          * @return array
 688          *
 689          * @todo Check for legal values where the DTD limits things.
 690          * @todo Check for unique id attribute :P
 691          */
 692         static function validateTagAttributes( $attribs, $element ) {
 693                 return Sanitizer::validateAttributes( $attribs,
 694                         Sanitizer::attributeWhitelist( $element ) );
 695         }
 696
 697         /**
 698          * Take an array of attribute names and values and normalize or discard
 699          * illegal values for the given whitelist.
 700          *
 701          * - Discards attributes not the given whitelist
 702          * - Unsafe style attributes are discarded
 703          * - Invalid id attributes are re-encoded
 704          *
 705          * @param array $attribs
 706          * @param array $whitelist list of allowed attribute names
 707          * @return array
 708          *
 709          * @todo Check for legal values where the DTD limits things.
 710          * @todo Check for unique id attribute :P
 711          */
 712         static function validateAttributes( $attribs, $whitelist ) {
 713                 global $wgAllowRdfaAttributes, $wgAllowMicrodataAttributes;
 714
 715                 $whitelist = array_flip( $whitelist );
 716                 $hrefExp = '/^(' . wfUrlProtocols() . ')[^\s]+$/';
 717
 718                 $out = array();
 719                 foreach ( $attribs as $attribute => $value ) {
 720                         #allow XML namespace declaration if RDFa is enabled
 721                         if ( $wgAllowRdfaAttributes && preg_match( self::XMLNS_ATTRIBUTE_PATTERN, $attribute ) ) {
 722                                 if ( !preg_match( self::EVIL_URI_PATTERN, $value ) ) {
 723                                         $out[$attribute] = $value;
 724                                 }
 725
 726                                 continue;
 727                         }
 728
 729                         # Allow any attribute beginning with "data-"
 730                         if ( !preg_match( '/^data-/i', $attribute ) && !isset( $whitelist[$attribute] ) ) {
 731                                 continue;
 732                         }
 733
 734                         # Strip javascript "expression" from stylesheets.
 735                         # http://msdn.microsoft.com/workshop/author/dhtml/overview/recalc.asp
 736                         if ( $attribute == 'style' ) {
 737                                 $value = Sanitizer::checkCss( $value );
 738                         }
 739
 740                         if ( $attribute === 'id' ) {
 741                                 $value = Sanitizer::escapeId( $value, 'noninitial' );
 742                         }
 743
 744                         # WAI-ARIA
 745                         # http://www.w3.org/TR/wai-aria/
 746                         # http://www.whatwg.org/html/elements.html#wai-aria
 747                         # For now we only support role="presentation" until we work out what roles should be
 748                         # usable by content and we ensure that our code explicitly rejects patterns that
 749                         # violate HTML5's ARIA restrictions.
 750                         if ( $attribute === 'role' && $value !== 'presentation' ) {
 751                                 continue;
 752                         }
 753
 754                         // RDFa and microdata properties allow URLs, URIs and/or CURIs.
 755                         // Check them for sanity.
 756                         if ( $attribute === 'rel' || $attribute === 'rev'
 757                                 # RDFa
 758                                 || $attribute === 'about' || $attribute === 'property'
 759                                 || $attribute === 'resource' || $attribute === 'datatype'
 760                                 || $attribute === 'typeof'
 761                                 # HTML5 microdata
 762                                 || $attribute === 'itemid' || $attribute === 'itemprop'
 763                                 || $attribute === 'itemref' || $attribute === 'itemscope'
 764                                 || $attribute === 'itemtype'
 765                         ) {
 766                                 //Paranoia. Allow "simple" values but suppress javascript
 767                                 if ( preg_match( self::EVIL_URI_PATTERN, $value ) ) {
 768                                         continue;
 769                                 }
 770                         }
 771
 772                         # NOTE: even though elements using href/src are not allowed directly, supply
 773                         #       validation code that can be used by tag hook handlers, etc
 774                         if ( $attribute === 'href' || $attribute === 'src' ) {
 775                                 if ( !preg_match( $hrefExp, $value ) ) {
 776                                         continue; //drop any href or src attributes not using an allowed protocol.
 777                                         // NOTE: this also drops all relative URLs
 778                                 }
 779                         }
 780
 781                         // If this attribute was previously set, override it.
 782                         // Output should only have one attribute of each name.
 783                         $out[$attribute] = $value;
 784                 }
 785
 786                 if ( $wgAllowMicrodataAttributes ) {
 787                         # itemtype, itemid, itemref don't make sense without itemscope
 788                         if ( !array_key_exists( 'itemscope', $out ) ) {
 789                                 unset( $out['itemtype'] );
 790                                 unset( $out['itemid'] );
 791                                 unset( $out['itemref'] );
 792                         }
 793                         # TODO: Strip itemprop if we aren't descendants of an itemscope or pointed to by an itemref.
 794                 }
 795                 return $out;
 796         }
 797
 798         /**
 799          * Merge two sets of HTML attributes.  Conflicting items in the second set
 800          * will override those in the first, except for 'class' attributes which
 801          * will be combined (if they're both strings).
 802          *
 803          * @todo implement merging for other attributes such as style
 804          * @param array $a
 805          * @param array $b
 806          * @return array
 807          */
 808         static function mergeAttributes( $a, $b ) {
 809                 $out = array_merge( $a, $b );
 810                 if ( isset( $a['class'] ) && isset( $b['class'] )
 811                         && is_string( $a['class'] ) && is_string( $b['class'] )
 812                         && $a['class'] !== $b['class']
 813                 ) {
 814                         $classes = preg_split( '/\s+/', "{$a['class']} {$b['class']}",
 815                                 -1, PREG_SPLIT_NO_EMPTY );
 816                         $out['class'] = implode( ' ', array_unique( $classes ) );
 817                 }
 818                 return $out;
 819         }
 820
 821         /**
 822          * Pick apart some CSS and check it for forbidden or unsafe structures.
 823          * Returns a sanitized string. This sanitized string will have
 824          * character references and escape sequences decoded and comments
 825          * stripped (unless it is itself one valid comment, in which case the value
 826          * will be passed through). If the input is just too evil, only a comment
 827          * complaining about evilness will be returned.
 828          *
 829          * Currently URL references, 'expression', 'tps' are forbidden.
 830          *
 831          * NOTE: Despite the fact that character references are decoded, the
 832          * returned string may contain character references given certain
 833          * clever input strings. These character references must
 834          * be escaped before the return value is embedded in HTML.
 835          *
 836          * @param string $value
 837          * @return string
 838          */
 839         static function checkCss( $value ) {
 840                 // Decode character references like &#123;
 841                 $value = Sanitizer::decodeCharReferences( $value );
 842
 843                 // Decode escape sequences and line continuation
 844                 // See the grammar in the CSS 2 spec, appendix D.
 845                 // This has to be done AFTER decoding character references.
 846                 // This means it isn't possible for this function to return
 847                 // unsanitized escape sequences. It is possible to manufacture
 848                 // input that contains character references that decode to
 849                 // escape sequences that decode to character references, but
 850                 // it's OK for the return value to contain character references
 851                 // because the caller is supposed to escape those anyway.
 852                 static $decodeRegex;
 853                 if ( !$decodeRegex ) {
 854                         $space = '[\\x20\\t\\r\\n\\f]';
 855                         $nl = '(?:\\n|\\r\\n|\\r|\\f)';
 856                         $backslash = '\\\\';
 857                         $decodeRegex = "/ $backslash
 858                                 (?:
 859                                         ($nl) |  # 1. Line continuation
 860                                         ([0-9A-Fa-f]{1,6})$space? |  # 2. character number
 861                                         (.) | # 3. backslash cancelling special meaning
 862                                         () | # 4. backslash at end of string
 863                                 )/xu";
 864                 }
 865                 $value = preg_replace_callback( $decodeRegex,
 866                         array( __CLASS__, 'cssDecodeCallback' ), $value );
 867
 868                 // Normalize Halfwidth and Fullwidth Unicode block that IE6 might treat as ascii
 869                 $value = preg_replace_callback(
 870                         '/[！-ｚ]/u', // U+FF01 to U+FF5A
 871                         function ( $matches ) {
 872                                 $cp = utf8ToCodepoint( $matches[0] );
 873                                 if ( $cp === false ) {
 874                                         return '';
 875                                 }
 876                                 return chr( $cp - 65248 ); // ASCII range \x21-\x7A
 877                         },
 878                         $value
 879                 );
 880
 881                 // Convert more characters IE6 might treat as ascii
 882                 // U+0280, U+0274, U+207F, U+029F, U+026A, U+207D, U+208D
 883                 $value = str_replace(
 884                         array( 'ʀ', 'ɴ', 'ⁿ', 'ʟ', 'ɪ', '⁽', '₍' ),
 885                         array( 'r', 'n', 'n', 'l', 'i', '(', '(' ),
 886                         $value
 887                 );
 888
 889                 // Let the value through if it's nothing but a single comment, to
 890                 // allow other functions which may reject it to pass some error
 891                 // message through.
 892                 if ( !preg_match( '! ^ \s* /\* [^*\\/]* \*/ \s* $ !x', $value ) ) {
 893                         // Remove any comments; IE gets token splitting wrong
 894                         // This must be done AFTER decoding character references and
 895                         // escape sequences, because those steps can introduce comments
 896                         // This step cannot introduce character references or escape
 897                         // sequences, because it replaces comments with spaces rather
 898                         // than removing them completely.
 899                         $value = StringUtils::delimiterReplace( '/*', '*/', ' ', $value );
 900
 901                         // Remove anything after a comment-start token, to guard against
 902                         // incorrect client implementations.
 903                         $commentPos = strpos( $value, '/*' );
 904                         if ( $commentPos !== false ) {
 905                                 $value = substr( $value, 0, $commentPos );
 906                         }
 907                 }
 908
 909                 // S followed by repeat, iteration, or prolonged sound marks,
 910                 // which IE will treat as "ss"
 911                 $value = preg_replace(
 912                         '/s(?:
 913                                 \xE3\x80\xB1 | # U+3031
 914                                 \xE3\x82\x9D | # U+309D
 915                                 \xE3\x83\xBC | # U+30FC
 916                                 \xE3\x83\xBD | # U+30FD
 917                                 \xEF\xB9\xBC | # U+FE7C
 918                                 \xEF\xB9\xBD | # U+FE7D
 919                                 \xEF\xBD\xB0   # U+FF70
 920                         )/ix',
 921                         'ss',
 922                         $value
 923                 );
 924
 925                 // Reject problematic keywords and control characters
 926                 if ( preg_match( '/[\000-\010\013\016-\037\177]/', $value ) ) {
 927                         return '/* invalid control char */';
 928                 } elseif ( preg_match(
 929                         '! expression | filter\s*: | accelerator\s*: | url\s*\( | image\s*\( | image-set\s*\( !ix',
 930                         $value
 931                 ) ) {
 932                         return '/* insecure input */';
 933                 }
 934                 return $value;
 935         }
 936
 937         /**
 938          * @param array $matches
 939          * @return string
 940          */
 941         static function cssDecodeCallback( $matches ) {
 942                 if ( $matches[1] !== '' ) {
 943                         // Line continuation
 944                         return '';
 945                 } elseif ( $matches[2] !== '' ) {
 946                         $char = codepointToUtf8( hexdec( $matches[2] ) );
 947                 } elseif ( $matches[3] !== '' ) {
 948                         $char = $matches[3];
 949                 } else {
 950                         $char = '\\';
 951                 }
 952                 if ( $char == "\n" || $char == '"' || $char == "'" || $char == '\\' ) {
 953                         // These characters need to be escaped in strings
 954                         // Clean up the escape sequence to avoid parsing errors by clients
 955                         return '\\' . dechex( ord( $char ) ) . ' ';
 956                 } else {
 957                         // Decode unnecessary escape
 958                         return $char;
 959                 }
 960         }
 961
 962         /**
 963          * Take a tag soup fragment listing an HTML element's attributes
 964          * and normalize it to well-formed XML, discarding unwanted attributes.
 965          * Output is safe for further wikitext processing, with escaping of
 966          * values that could trigger problems.
 967          *
 968          * - Normalizes attribute names to lowercase
 969          * - Discards attributes not on a whitelist for the given element
 970          * - Turns broken or invalid entities into plaintext
 971          * - Double-quotes all attribute values
 972          * - Attributes without values are given the name as attribute
 973          * - Double attributes are discarded
 974          * - Unsafe style attributes are discarded
 975          * - Prepends space if there are attributes.
 976          *
 977          * @param string $text
 978          * @param string $element
 979          * @return string
 980          */
 981         static function fixTagAttributes( $text, $element ) {
 982                 if ( trim( $text ) == '' ) {
 983                         return '';
 984                 }
 985
 986                 $decoded = Sanitizer::decodeTagAttributes( $text );
 987                 $stripped = Sanitizer::validateTagAttributes( $decoded, $element );
 988
 989                 return Sanitizer::safeEncodeTagAttributes( $stripped );
 990         }
 991
 992         /**
 993          * Encode an attribute value for HTML output.
 994          * @param string $text
 995          * @return string HTML-encoded text fragment
 996          */
 997         static function encodeAttribute( $text ) {
 998                 $encValue = htmlspecialchars( $text, ENT_QUOTES );
 999
1000                 // Whitespace is normalized during attribute decoding,
1001                 // so if we've been passed non-spaces we must encode them
1002                 // ahead of time or they won't be preserved.
1003                 $encValue = strtr( $encValue, array(
1004                         "\n" => '&#10;',
1005                         "\r" => '&#13;',
1006                         "\t" => '&#9;',
1007                 ) );
1008
1009                 return $encValue;
1010         }
1011
1012         /**
1013          * Encode an attribute value for HTML tags, with extra armoring
1014          * against further wiki processing.
1015          * @param string $text
1016          * @return string HTML-encoded text fragment
1017          */
1018         static function safeEncodeAttribute( $text ) {
1019                 $encValue = Sanitizer::encodeAttribute( $text );
1020
1021                 # Templates and links may be expanded in later parsing,
1022                 # creating invalid or dangerous output. Suppress this.
1023                 $encValue = strtr( $encValue, array(
1024                         '<'    => '&lt;',   // This should never happen,
1025                         '>'    => '&gt;',   // we've received invalid input
1026                         '"'    => '&quot;', // which should have been escaped.
1027                         '{'    => '&#123;',
1028                         '['    => '&#91;',
1029                         "''"   => '&#39;&#39;',
1030                         'ISBN' => '&#73;SBN',
1031                         'RFC'  => '&#82;FC',
1032                         'PMID' => '&#80;MID',
1033                         '|'    => '&#124;',
1034                         '__'   => '&#95;_',
1035                 ) );
1036
1037                 # Stupid hack
1038                 $encValue = preg_replace_callback(
1039                         '/((?i)' . wfUrlProtocols() . ')/',
1040                         array( 'Sanitizer', 'armorLinksCallback' ),
1041                         $encValue );
1042                 return $encValue;
1043         }
1044
1045         /**
1046          * Given a value, escape it so that it can be used in an id attribute and
1047          * return it.  This will use HTML5 validation if $wgExperimentalHtmlIds is
1048          * true, allowing anything but ASCII whitespace.  Otherwise it will use
1049          * HTML 4 rules, which means a narrow subset of ASCII, with bad characters
1050          * escaped with lots of dots.
1051          *
1052          * To ensure we don't have to bother escaping anything, we also strip ', ",
1053          * & even if $wgExperimentalIds is true.  TODO: Is this the best tactic?
1054          * We also strip # because it upsets IE, and % because it could be
1055          * ambiguous if it's part of something that looks like a percent escape
1056          * (which don't work reliably in fragments cross-browser).
1057          *
1058          * @see http://www.w3.org/TR/html401/types.html#type-name Valid characters
1059          *   in the id and name attributes
1060          * @see http://www.w3.org/TR/html401/struct/links.html#h-12.2.3 Anchors with
1061          *   the id attribute
1062          * @see http://www.whatwg.org/html/elements.html#the-id-attribute
1063          *   HTML5 definition of id attribute
1064          *
1065          * @param string $id id to escape
1066          * @param $options Mixed: string or array of strings (default is array()):
1067          *   'noninitial': This is a non-initial fragment of an id, not a full id,
1068          *       so don't pay attention if the first character isn't valid at the
1069          *       beginning of an id.  Only matters if $wgExperimentalHtmlIds is
1070          *       false.
1071          *   'legacy': Behave the way the old HTML 4-based ID escaping worked even
1072          *       if $wgExperimentalHtmlIds is used, so we can generate extra
1073          *       anchors and links won't break.
1074          * @return string
1075          */
1076         static function escapeId( $id, $options = array() ) {
1077                 global $wgExperimentalHtmlIds;
1078                 $options = (array)$options;
1079
1080                 if ( $wgExperimentalHtmlIds && !in_array( 'legacy', $options ) ) {
1081                         $id = Sanitizer::decodeCharReferences( $id );
1082                         $id = preg_replace( '/[ \t\n\r\f_\'"&#%]+/', '_', $id );
1083                         $id = trim( $id, '_' );
1084                         if ( $id === '' ) {
1085                                 # Must have been all whitespace to start with.
1086                                 return '_';
1087                         } else {
1088                                 return $id;
1089                         }
1090                 }
1091
1092                 # HTML4-style escaping
1093                 static $replace = array(
1094                         '%3A' => ':',
1095                         '%' => '.'
1096                 );
1097
1098                 $id = urlencode( Sanitizer::decodeCharReferences( strtr( $id, ' ', '_' ) ) );
1099                 $id = str_replace( array_keys( $replace ), array_values( $replace ), $id );
1100
1101                 if ( !preg_match( '/^[a-zA-Z]/', $id )
1102                 && !in_array( 'noninitial', $options ) ) {
1103                         // Initial character must be a letter!
1104                         $id = "x$id";
1105                 }
1106                 return $id;
1107         }
1108
1109         /**
1110          * Given a value, escape it so that it can be used as a CSS class and
1111          * return it.
1112          *
1113          * @todo For extra validity, input should be validated UTF-8.
1114          *
1115          * @see http://www.w3.org/TR/CSS21/syndata.html Valid characters/format
1116          *
1117          * @param string $class
1118          * @return string
1119          */
1120         static function escapeClass( $class ) {
1121                 // Convert ugly stuff to underscores and kill underscores in ugly places
1122                 return rtrim( preg_replace(
1123                         array( '/(^[0-9\\-])|[\\x00-\\x20!"#$%&\'()*+,.\\/:;<=>?@[\\]^`{|}~]|\\xC2\\xA0/', '/_+/' ),
1124                         '_',
1125                         $class ), '_' );
1126         }
1127
1128         /**
1129          * Given HTML input, escape with htmlspecialchars but un-escape entities.
1130          * This allows (generally harmless) entities like &#160; to survive.
1131          *
1132          * @param string $html HTML to escape
1133          * @return string: escaped input
1134          */
1135         static function escapeHtmlAllowEntities( $html ) {
1136                 $html = Sanitizer::decodeCharReferences( $html );
1137                 # It seems wise to escape ' as well as ", as a matter of course.  Can't
1138                 # hurt.
1139                 $html = htmlspecialchars( $html, ENT_QUOTES );
1140                 return $html;
1141         }
1142
1143         /**
1144          * Regex replace callback for armoring links against further processing.
1145          * @param array $matches
1146          * @return string
1147          */
1148         private static function armorLinksCallback( $matches ) {
1149                 return str_replace( ':', '&#58;', $matches[1] );
1150         }
1151
1152         /**
1153          * Return an associative array of attribute names and values from
1154          * a partial tag string. Attribute names are forces to lowercase,
1155          * character references are decoded to UTF-8 text.
1156          *
1157          * @param string $text
1158          * @return array
1159          */
1160         public static function decodeTagAttributes( $text ) {
1161                 if ( trim( $text ) == '' ) {
1162                         return array();
1163                 }
1164
1165                 $attribs = array();
1166                 $pairs = array();
1167                 if ( !preg_match_all(
1168                         self::getAttribsRegex(),
1169                         $text,
1170                         $pairs,
1171                         PREG_SET_ORDER ) ) {
1172                         return $attribs;
1173                 }
1174
1175                 foreach ( $pairs as $set ) {
1176                         $attribute = strtolower( $set[1] );
1177                         $value = Sanitizer::getTagAttributeCallback( $set );
1178
1179                         // Normalize whitespace
1180                         $value = preg_replace( '/[\t\r\n ]+/', ' ', $value );
1181                         $value = trim( $value );
1182
1183                         // Decode character references
1184                         $attribs[$attribute] = Sanitizer::decodeCharReferences( $value );
1185                 }
1186                 return $attribs;
1187         }
1188
1189         /**
1190          * Build a partial tag string from an associative array of attribute
1191          * names and values as returned by decodeTagAttributes.
1192          *
1193          * @param array $assoc_array
1194          * @return string
1195          */
1196         public static function safeEncodeTagAttributes( $assoc_array ) {
1197                 $attribs = array();
1198                 foreach ( $assoc_array as $attribute => $value ) {
1199                         $encAttribute = htmlspecialchars( $attribute );
1200                         $encValue = Sanitizer::safeEncodeAttribute( $value );
1201
1202                         $attribs[] = "$encAttribute=\"$encValue\"";
1203                 }
1204                 return count( $attribs ) ? ' ' . implode( ' ', $attribs ) : '';
1205         }
1206
1207         /**
1208          * Pick the appropriate attribute value from a match set from the
1209          * attribs regex matches.
1210          *
1211          * @param array $set
1212          * @throws MWException when tag conditions are not met.
1213          * @return string
1214          */
1215         private static function getTagAttributeCallback( $set ) {
1216                 if ( isset( $set[6] ) ) {
1217                         # Illegal #XXXXXX color with no quotes.
1218                         return $set[6];
1219                 } elseif ( isset( $set[5] ) ) {
1220                         # No quotes.
1221                         return $set[5];
1222                 } elseif ( isset( $set[4] ) ) {
1223                         # Single-quoted
1224                         return $set[4];
1225                 } elseif ( isset( $set[3] ) ) {
1226                         # Double-quoted
1227                         return $set[3];
1228                 } elseif ( !isset( $set[2] ) ) {
1229                         # In XHTML, attributes must have a value.
1230                         # For 'reduced' form, return explicitly the attribute name here.
1231                         return $set[1];
1232                 } else {
1233                         throw new MWException( "Tag conditions not met. This should never happen and is a bug." );
1234                 }
1235         }
1236
1237         /**
1238          * Normalize whitespace and character references in an XML source-
1239          * encoded text for an attribute value.
1240          *
1241          * See http://www.w3.org/TR/REC-xml/#AVNormalize for background,
1242          * but note that we're not returning the value, but are returning
1243          * XML source fragments that will be slapped into output.
1244          *
1245          * @param string $text
1246          * @return string
1247          * @todo Remove, unused?
1248          */
1249         private static function normalizeAttributeValue( $text ) {
1250                 return str_replace( '"', '&quot;',
1251                         self::normalizeWhitespace(
1252                                 Sanitizer::normalizeCharReferences( $text ) ) );
1253         }
1254
1255         /**
1256          * @param string $text
1257          * @return string
1258          */
1259         private static function normalizeWhitespace( $text ) {
1260                 return preg_replace(
1261                         '/\r\n|[\x20\x0d\x0a\x09]/',
1262                         ' ',
1263                         $text );
1264         }
1265
1266         /**
1267          * Normalizes whitespace in a section name, such as might be returned
1268          * by Parser::stripSectionName(), for use in the id's that are used for
1269          * section links.
1270          *
1271          * @param string $section
1272          * @return string
1273          */
1274         static function normalizeSectionNameWhitespace( $section ) {
1275                 return trim( preg_replace( '/[ _]+/', ' ', $section ) );
1276         }
1277
1278         /**
1279          * Ensure that any entities and character references are legal
1280          * for XML and XHTML specifically. Any stray bits will be
1281          * &amp;-escaped to result in a valid text fragment.
1282          *
1283          * a. named char refs can only be &lt; &gt; &amp; &quot;, others are
1284          *   numericized (this way we're well-formed even without a DTD)
1285          * b. any numeric char refs must be legal chars, not invalid or forbidden
1286          * c. use lower cased "&#x", not "&#X"
1287          * d. fix or reject non-valid attributes
1288          *
1289          * @param string $text
1290          * @return string
1291          * @private
1292          */
1293         static function normalizeCharReferences( $text ) {
1294                 return preg_replace_callback(
1295                         self::CHAR_REFS_REGEX,
1296                         array( 'Sanitizer', 'normalizeCharReferencesCallback' ),
1297                         $text );
1298         }
1299         /**
1300          * @param string $matches
1301          * @return string
1302          */
1303         static function normalizeCharReferencesCallback( $matches ) {
1304                 $ret = null;
1305                 if ( $matches[1] != '' ) {
1306                         $ret = Sanitizer::normalizeEntity( $matches[1] );
1307                 } elseif ( $matches[2] != '' ) {
1308                         $ret = Sanitizer::decCharReference( $matches[2] );
1309                 } elseif ( $matches[3] != '' ) {
1310                         $ret = Sanitizer::hexCharReference( $matches[3] );
1311                 }
1312                 if ( is_null( $ret ) ) {
1313                         return htmlspecialchars( $matches[0] );
1314                 } else {
1315                         return $ret;
1316                 }
1317         }
1318
1319         /**
1320          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1321          * return the equivalent numeric entity reference (except for the core &lt;
1322          * &gt; &amp; &quot;). If the entity is a MediaWiki-specific alias, returns
1323          * the HTML equivalent. Otherwise, returns HTML-escaped text of
1324          * pseudo-entity source (eg &amp;foo;)
1325          *
1326          * @param string $name
1327          * @return string
1328          */
1329         static function normalizeEntity( $name ) {
1330                 if ( isset( self::$htmlEntityAliases[$name] ) ) {
1331                         return '&' . self::$htmlEntityAliases[$name] . ';';
1332                 } elseif ( in_array( $name,
1333                 array( 'lt', 'gt', 'amp', 'quot' ) ) ) {
1334                         return "&$name;";
1335                 } elseif ( isset( self::$htmlEntities[$name] ) ) {
1336                         return '&#' . self::$htmlEntities[$name] . ';';
1337                 } else {
1338                         return "&amp;$name;";
1339                 }
1340         }
1341
1342         /**
1343          * @param int $codepoint
1344          * @return null|string
1345          */
1346         static function decCharReference( $codepoint ) {
1347                 $point = intval( $codepoint );
1348                 if ( Sanitizer::validateCodepoint( $point ) ) {
1349                         return sprintf( '&#%d;', $point );
1350                 } else {
1351                         return null;
1352                 }
1353         }
1354
1355         /**
1356          * @param int $codepoint
1357          * @return null|string
1358          */
1359         static function hexCharReference( $codepoint ) {
1360                 $point = hexdec( $codepoint );
1361                 if ( Sanitizer::validateCodepoint( $point ) ) {
1362                         return sprintf( '&#x%x;', $point );
1363                 } else {
1364                         return null;
1365                 }
1366         }
1367
1368         /**
1369          * Returns true if a given Unicode codepoint is a valid character in XML.
1370          * @param int $codepoint
1371          * @return bool
1372          */
1373         private static function validateCodepoint( $codepoint ) {
1374                 return $codepoint == 0x09
1375                         || $codepoint == 0x0a
1376                         || $codepoint == 0x0d
1377                         || ( $codepoint >= 0x20 && $codepoint <= 0xd7ff )
1378                         || ( $codepoint >= 0xe000 && $codepoint <= 0xfffd )
1379                         || ( $codepoint >= 0x10000 && $codepoint <= 0x10ffff );
1380         }
1381
1382         /**
1383          * Decode any character references, numeric or named entities,
1384          * in the text and return a UTF-8 string.
1385          *
1386          * @param string $text
1387          * @return string
1388          */
1389         public static function decodeCharReferences( $text ) {
1390                 return preg_replace_callback(
1391                         self::CHAR_REFS_REGEX,
1392                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1393                         $text );
1394         }
1395
1396         /**
1397          * Decode any character references, numeric or named entities,
1398          * in the next and normalize the resulting string. (bug 14952)
1399          *
1400          * This is useful for page titles, not for text to be displayed,
1401          * MediaWiki allows HTML entities to escape normalization as a feature.
1402          *
1403          * @param string $text Already normalized, containing entities
1404          * @return string Still normalized, without entities
1405          */
1406         public static function decodeCharReferencesAndNormalize( $text ) {
1407                 global $wgContLang;
1408                 $text = preg_replace_callback(
1409                         self::CHAR_REFS_REGEX,
1410                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1411                         $text, /* limit */ -1, $count );
1412
1413                 if ( $count ) {
1414                         return $wgContLang->normalize( $text );
1415                 } else {
1416                         return $text;
1417                 }
1418         }
1419
1420         /**
1421          * @param string $matches
1422          * @return string
1423          */
1424         static function decodeCharReferencesCallback( $matches ) {
1425                 if ( $matches[1] != '' ) {
1426                         return Sanitizer::decodeEntity( $matches[1] );
1427                 } elseif ( $matches[2] != '' ) {
1428                         return Sanitizer::decodeChar( intval( $matches[2] ) );
1429                 } elseif ( $matches[3] != '' ) {
1430                         return Sanitizer::decodeChar( hexdec( $matches[3] ) );
1431                 }
1432                 # Last case should be an ampersand by itself
1433                 return $matches[0];
1434         }
1435
1436         /**
1437          * Return UTF-8 string for a codepoint if that is a valid
1438          * character reference, otherwise U+FFFD REPLACEMENT CHARACTER.
1439          * @param int $codepoint
1440          * @return string
1441          * @private
1442          */
1443         static function decodeChar( $codepoint ) {
1444                 if ( Sanitizer::validateCodepoint( $codepoint ) ) {
1445                         return codepointToUtf8( $codepoint );
1446                 } else {
1447                         return UTF8_REPLACEMENT;
1448                 }
1449         }
1450
1451         /**
1452          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1453          * return the UTF-8 encoding of that character. Otherwise, returns
1454          * pseudo-entity source (eg "&foo;")
1455          *
1456          * @param string $name
1457          * @return string
1458          */
1459         static function decodeEntity( $name ) {
1460                 if ( isset( self::$htmlEntityAliases[$name] ) ) {
1461                         $name = self::$htmlEntityAliases[$name];
1462                 }
1463                 if ( isset( self::$htmlEntities[$name] ) ) {
1464                         return codepointToUtf8( self::$htmlEntities[$name] );
1465                 } else {
1466                         return "&$name;";
1467                 }
1468         }
1469
1470         /**
1471          * Fetch the whitelist of acceptable attributes for a given element name.
1472          *
1473          * @param string $element
1474          * @return array
1475          */
1476         static function attributeWhitelist( $element ) {
1477                 $list = Sanitizer::setupAttributeWhitelist();
1478                 return isset( $list[$element] )
1479                         ? $list[$element]
1480                         : array();
1481         }
1482
1483         /**
1484          * Foreach array key (an allowed HTML element), return an array
1485          * of allowed attributes
1486          * @return array
1487          */
1488         static function setupAttributeWhitelist() {
1489                 global $wgAllowRdfaAttributes, $wgAllowMicrodataAttributes;
1490
1491                 static $whitelist, $staticInitialised;
1492                 $globalContext = implode( '-', compact( 'wgAllowRdfaAttributes', 'wgAllowMicrodataAttributes' ) );
1493
1494                 if ( isset( $whitelist ) && $staticInitialised == $globalContext ) {
1495                         return $whitelist;
1496                 }
1497
1498                 $common = array(
1499                         # HTML
1500                         'id',
1501                         'class',
1502                         'style',
1503                         'lang',
1504                         'dir',
1505                         'title',
1506
1507                         # WAI-ARIA
1508                         'role',
1509                 );
1510
1511                 if ( $wgAllowRdfaAttributes ) {
1512                         # RDFa attributes as specified in section 9 of
1513                         # http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014
1514                         $common = array_merge( $common, array(
1515                                 'about', 'property', 'resource', 'datatype', 'typeof',
1516                         ) );
1517                 }
1518
1519                 if ( $wgAllowMicrodataAttributes ) {
1520                         # add HTML5 microdata tags as specified by
1521                         # http://www.whatwg.org/html/microdata.html#the-microdata-model
1522                         $common = array_merge( $common, array(
1523                                 'itemid', 'itemprop', 'itemref', 'itemscope', 'itemtype'
1524                         ) );
1525                 }
1526
1527                 $block = array_merge( $common, array( 'align' ) );
1528                 $tablealign = array( 'align', 'valign' );
1529                 $tablecell = array(
1530                         'abbr',
1531                         'axis',
1532                         'headers',
1533                         'scope',
1534                         'rowspan',
1535                         'colspan',
1536                         'nowrap', # deprecated
1537                         'width', # deprecated
1538                         'height', # deprecated
1539                         'bgcolor', # deprecated
1540                 );
1541
1542                 # Numbers refer to sections in HTML 4.01 standard describing the element.
1543                 # See: http://www.w3.org/TR/html4/
1544                 $whitelist = array(
1545                         # 7.5.4
1546                         'div'        => $block,
1547                         'center'     => $common, # deprecated
1548                         'span'       => $common,
1549
1550                         # 7.5.5
1551                         'h1'         => $block,
1552                         'h2'         => $block,
1553                         'h3'         => $block,
1554                         'h4'         => $block,
1555                         'h5'         => $block,
1556                         'h6'         => $block,
1557
1558                         # 7.5.6
1559                         # address
1560
1561                         # 8.2.4
1562                         'bdo'        => $common,
1563
1564                         # 9.2.1
1565                         'em'         => $common,
1566                         'strong'     => $common,
1567                         'cite'       => $common,
1568                         'dfn'        => $common,
1569                         'code'       => $common,
1570                         'samp'       => $common,
1571                         'kbd'        => $common,
1572                         'var'        => $common,
1573                         'abbr'       => $common,
1574                         # acronym
1575
1576                         # 9.2.2
1577                         'blockquote' => array_merge( $common, array( 'cite' ) ),
1578                         'q'          => array_merge( $common, array( 'cite' ) ),
1579
1580                         # 9.2.3
1581                         'sub'        => $common,
1582                         'sup'        => $common,
1583
1584                         # 9.3.1
1585                         'p'          => $block,
1586
1587                         # 9.3.2
1588                         'br'         => array_merge( $common, array( 'clear' ) ),
1589
1590                         # http://www.whatwg.org/html/text-level-semantics.html#the-wbr-element
1591                         'wbr'        => $common,
1592
1593                         # 9.3.4
1594                         'pre'        => array_merge( $common, array( 'width' ) ),
1595
1596                         # 9.4
1597                         'ins'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1598                         'del'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1599
1600                         # 10.2
1601                         'ul'         => array_merge( $common, array( 'type' ) ),
1602                         'ol'         => array_merge( $common, array( 'type', 'start' ) ),
1603                         'li'         => array_merge( $common, array( 'type', 'value' ) ),
1604
1605                         # 10.3
1606                         'dl'         => $common,
1607                         'dd'         => $common,
1608                         'dt'         => $common,
1609
1610                         # 11.2.1
1611                         'table'      => array_merge( $common,
1612                                                                 array( 'summary', 'width', 'border', 'frame',
1613                                                                                 'rules', 'cellspacing', 'cellpadding',
1614                                                                                 'align', 'bgcolor',
1615                                                                 ) ),
1616
1617                         # 11.2.2
1618                         'caption'    => $block,
1619
1620                         # 11.2.3
1621                         'thead'      => $common,
1622                         'tfoot'      => $common,
1623                         'tbody'      => $common,
1624
1625                         # 11.2.4
1626                         'colgroup'   => array_merge( $common, array( 'span' ) ),
1627                         'col'        => array_merge( $common, array( 'span' ) ),
1628
1629                         # 11.2.5
1630                         'tr'         => array_merge( $common, array( 'bgcolor' ), $tablealign ),
1631
1632                         # 11.2.6
1633                         'td'         => array_merge( $common, $tablecell, $tablealign ),
1634                         'th'         => array_merge( $common, $tablecell, $tablealign ),
1635
1636                         # 12.2
1637                         # NOTE: <a> is not allowed directly, but the attrib
1638                         # whitelist is used from the Parser object
1639                         'a'          => array_merge( $common, array( 'href', 'rel', 'rev' ) ), # rel/rev esp. for RDFa
1640
1641                         # 13.2
1642                         # Not usually allowed, but may be used for extension-style hooks
1643                         # such as <math> when it is rasterized, or if $wgAllowImageTag is
1644                         # true
1645                         'img'        => array_merge( $common, array( 'alt', 'src', 'width', 'height' ) ),
1646
1647                         # 15.2.1
1648                         'tt'         => $common,
1649                         'b'          => $common,
1650                         'i'          => $common,
1651                         'big'        => $common,
1652                         'small'      => $common,
1653                         'strike'     => $common,
1654                         's'          => $common,
1655                         'u'          => $common,
1656
1657                         # 15.2.2
1658                         'font'       => array_merge( $common, array( 'size', 'color', 'face' ) ),
1659                         # basefont
1660
1661                         # 15.3
1662                         'hr'         => array_merge( $common, array( 'width' ) ),
1663
1664                         # HTML Ruby annotation text module, simple ruby only.
1665                         # http://www.whatwg.org/html/text-level-semantics.html#the-ruby-element
1666                         'ruby'       => $common,
1667                         # rbc
1668                         # rtc
1669                         'rb'         => $common,
1670                         'rt'         => $common, #array_merge( $common, array( 'rbspan' ) ),
1671                         'rp'         => $common,
1672
1673                         # MathML root element, where used for extensions
1674                         # 'title' may not be 100% valid here; it's XHTML
1675                         # http://www.w3.org/TR/REC-MathML/
1676                         'math'       => array( 'class', 'style', 'id', 'title' ),
1677
1678                         # HTML 5 section 4.6
1679                         'bdi' => $common,
1680
1681                         # HTML5 elements, defined by:
1682                         # http://www.whatwg.org/html/
1683                         'data' => array_merge( $common, array( 'value' ) ),
1684                         'time' => array_merge( $common, array( 'datetime' ) ),
1685                         'mark' => $common,
1686
1687                         // meta and link are only permitted by removeHTMLtags when Microdata
1688                         // is enabled so we don't bother adding a conditional to hide these
1689                         // Also meta and link are only valid in WikiText as Microdata elements
1690                         // (ie: validateTag rejects tags missing the attributes needed for Microdata)
1691                         // So we don't bother including $common attributes that have no purpose.
1692                         'meta' => array( 'itemprop', 'content' ),
1693                         'link' => array( 'itemprop', 'href' ),
1694                 );
1695
1696                 $staticInitialised = $globalContext;
1697
1698                 return $whitelist;
1699         }
1700
1701         /**
1702          * Take a fragment of (potentially invalid) HTML and return
1703          * a version with any tags removed, encoded as plain text.
1704          *
1705          * Warning: this return value must be further escaped for literal
1706          * inclusion in HTML output as of 1.10!
1707          *
1708          * @param string $text HTML fragment
1709          * @return string
1710          */
1711         static function stripAllTags( $text ) {
1712                 # Actual <tags>
1713                 $text = StringUtils::delimiterReplace( '<', '>', '', $text );
1714
1715                 # Normalize &entities and whitespace
1716                 $text = self::decodeCharReferences( $text );
1717                 $text = self::normalizeWhitespace( $text );
1718
1719                 return $text;
1720         }
1721
1722         /**
1723          * Hack up a private DOCTYPE with HTML's standard entity declarations.
1724          * PHP 4 seemed to know these if you gave it an HTML doctype, but
1725          * PHP 5.1 doesn't.
1726          *
1727          * Use for passing XHTML fragments to PHP's XML parsing functions
1728          *
1729          * @return string
1730          */
1731         static function hackDocType() {
1732                 $out = "<!DOCTYPE html [\n";
1733                 foreach ( self::$htmlEntities as $entity => $codepoint ) {
1734                         $out .= "<!ENTITY $entity \"&#$codepoint;\">";
1735                 }
1736                 $out .= "]>\n";
1737                 return $out;
1738         }
1739
1740         /**
1741          * @param string $url
1742          * @return mixed|string
1743          */
1744         static function cleanUrl( $url ) {
1745                 # Normalize any HTML entities in input. They will be
1746                 # re-escaped by makeExternalLink().
1747                 $url = Sanitizer::decodeCharReferences( $url );
1748
1749                 # Escape any control characters introduced by the above step
1750                 $url = preg_replace_callback( '/[\][<>"\\x00-\\x20\\x7F\|]/',
1751                         array( __CLASS__, 'cleanUrlCallback' ), $url );
1752
1753                 # Validate hostname portion
1754                 $matches = array();
1755                 if ( preg_match( '!^([^:]+:)(//[^/]+)?(.*)$!iD', $url, $matches ) ) {
1756                         list( /* $whole */, $protocol, $host, $rest ) = $matches;
1757
1758                         // Characters that will be ignored in IDNs.
1759                         // http://tools.ietf.org/html/3454#section-3.1
1760                         // Strip them before further processing so blacklists and such work.
1761                         $strip = "/
1762                                 \\s|          # general whitespace
1763                                 \xc2\xad|     # 00ad SOFT HYPHEN
1764                                 \xe1\xa0\x86| # 1806 MONGOLIAN TODO SOFT HYPHEN
1765                                 \xe2\x80\x8b| # 200b ZERO WIDTH SPACE
1766                                 \xe2\x81\xa0| # 2060 WORD JOINER
1767                                 \xef\xbb\xbf| # feff ZERO WIDTH NO-BREAK SPACE
1768                                 \xcd\x8f|     # 034f COMBINING GRAPHEME JOINER
1769                                 \xe1\xa0\x8b| # 180b MONGOLIAN FREE VARIATION SELECTOR ONE
1770                                 \xe1\xa0\x8c| # 180c MONGOLIAN FREE VARIATION SELECTOR TWO
1771                                 \xe1\xa0\x8d| # 180d MONGOLIAN FREE VARIATION SELECTOR THREE
1772                                 \xe2\x80\x8c| # 200c ZERO WIDTH NON-JOINER
1773                                 \xe2\x80\x8d| # 200d ZERO WIDTH JOINER
1774                                 [\xef\xb8\x80-\xef\xb8\x8f] # fe00-fe0f VARIATION SELECTOR-1-16
1775                                 /xuD";
1776
1777                         $host = preg_replace( $strip, '', $host );
1778
1779                         // @todo FIXME: Validate hostnames here
1780
1781                         return $protocol . $host . $rest;
1782                 } else {
1783                         return $url;
1784                 }
1785         }
1786
1787         /**
1788          * @param array $matches
1789          * @return string
1790          */
1791         static function cleanUrlCallback( $matches ) {
1792                 return urlencode( $matches[0] );
1793         }
1794
1795         /**
1796          * Does a string look like an e-mail address?
1797          *
1798          * This validates an email address using an HTML5 specification found at:
1799          * http://www.whatwg.org/html/states-of-the-type-attribute.html#valid-e-mail-address
1800          * Which as of 2011-01-24 says:
1801          *
1802          *   A valid e-mail address is a string that matches the ABNF production
1803          *   1*( atext / "." ) "@" ldh-str *( "." ldh-str ) where atext is defined
1804          *   in RFC 5322 section 3.2.3, and ldh-str is defined in RFC 1034 section
1805          *   3.5.
1806          *
1807          * This function is an implementation of the specification as requested in
1808          * bug 22449.
1809          *
1810          * Client-side forms will use the same standard validation rules via JS or
1811          * HTML 5 validation; additional restrictions can be enforced server-side
1812          * by extensions via the 'isValidEmailAddr' hook.
1813          *
1814          * Note that this validation doesn't 100% match RFC 2822, but is believed
1815          * to be liberal enough for wide use. Some invalid addresses will still
1816          * pass validation here.
1817          *
1818          * @since 1.18
1819          *
1820          * @param string $addr E-mail address
1821          * @return bool
1822          */
1823         public static function validateEmail( $addr ) {
1824                 $result = null;
1825                 if ( !wfRunHooks( 'isValidEmailAddr', array( $addr, &$result ) ) ) {
1826                         return $result;
1827                 }
1828
1829                 // Please note strings below are enclosed in brackets [], this make the
1830                 // hyphen "-" a range indicator. Hence it is double backslashed below.
1831                 // See bug 26948
1832                 $rfc5322_atext = "a-z0-9!#$%&'*+\\-\/=?^_`{|}~";
1833                 $rfc1034_ldh_str = "a-z0-9\\-";
1834
1835                 $HTML5_email_regexp = "/
1836                 ^                      # start of string
1837                 [$rfc5322_atext\\.]+    # user part which is liberal :p
1838                 @                      # 'apostrophe'
1839                 [$rfc1034_ldh_str]+       # First domain part
1840                 (\\.[$rfc1034_ldh_str]+)*  # Following part prefixed with a dot
1841                 $                      # End of string
1842                 /ix"; // case Insensitive, eXtended
1843
1844                 return (bool)preg_match( $HTML5_email_regexp, $addr );
1845         }
1846 }