includes/Sanitizer.php

   1 <?php
   2 /**
   3  * XHTML 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  * XHTML 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          * @private
  58          */
  59         static $htmlEntities = array(
  60                 'Aacute'   => 193,
  61                 'aacute'   => 225,
  62                 'Acirc'    => 194,
  63                 'acirc'    => 226,
  64                 'acute'    => 180,
  65                 'AElig'    => 198,
  66                 'aelig'    => 230,
  67                 'Agrave'   => 192,
  68                 'agrave'   => 224,
  69                 'alefsym'  => 8501,
  70                 'Alpha'    => 913,
  71                 'alpha'    => 945,
  72                 'amp'      => 38,
  73                 'and'      => 8743,
  74                 'ang'      => 8736,
  75                 'apos'     => 39, // New in XHTML & HTML 5; avoid in output for compatibility with IE.
  76                 'Aring'    => 197,
  77                 'aring'    => 229,
  78                 'asymp'    => 8776,
  79                 'Atilde'   => 195,
  80                 'atilde'   => 227,
  81                 'Auml'     => 196,
  82                 'auml'     => 228,
  83                 'bdquo'    => 8222,
  84                 'Beta'     => 914,
  85                 'beta'     => 946,
  86                 'brvbar'   => 166,
  87                 'bull'     => 8226,
  88                 'cap'      => 8745,
  89                 'Ccedil'   => 199,
  90                 'ccedil'   => 231,
  91                 'cedil'    => 184,
  92                 'cent'     => 162,
  93                 'Chi'      => 935,
  94                 'chi'      => 967,
  95                 'circ'     => 710,
  96                 'clubs'    => 9827,
  97                 'cong'     => 8773,
  98                 'copy'     => 169,
  99                 'crarr'    => 8629,
 100                 'cup'      => 8746,
 101                 'curren'   => 164,
 102                 'dagger'   => 8224,
 103                 'Dagger'   => 8225,
 104                 'darr'     => 8595,
 105                 'dArr'     => 8659,
 106                 'deg'      => 176,
 107                 'Delta'    => 916,
 108                 'delta'    => 948,
 109                 'diams'    => 9830,
 110                 'divide'   => 247,
 111                 'Eacute'   => 201,
 112                 'eacute'   => 233,
 113                 'Ecirc'    => 202,
 114                 'ecirc'    => 234,
 115                 'Egrave'   => 200,
 116                 'egrave'   => 232,
 117                 'empty'    => 8709,
 118                 'emsp'     => 8195,
 119                 'ensp'     => 8194,
 120                 'Epsilon'  => 917,
 121                 'epsilon'  => 949,
 122                 'equiv'    => 8801,
 123                 'Eta'      => 919,
 124                 'eta'      => 951,
 125                 'ETH'      => 208,
 126                 'eth'      => 240,
 127                 'Euml'     => 203,
 128                 'euml'     => 235,
 129                 'euro'     => 8364,
 130                 'exist'    => 8707,
 131                 'fnof'     => 402,
 132                 'forall'   => 8704,
 133                 'frac12'   => 189,
 134                 'frac14'   => 188,
 135                 'frac34'   => 190,
 136                 'frasl'    => 8260,
 137                 'Gamma'    => 915,
 138                 'gamma'    => 947,
 139                 'ge'       => 8805,
 140                 'gt'       => 62,
 141                 'harr'     => 8596,
 142                 'hArr'     => 8660,
 143                 'hearts'   => 9829,
 144                 'hellip'   => 8230,
 145                 'Iacute'   => 205,
 146                 'iacute'   => 237,
 147                 'Icirc'    => 206,
 148                 'icirc'    => 238,
 149                 'iexcl'    => 161,
 150                 'Igrave'   => 204,
 151                 'igrave'   => 236,
 152                 'image'    => 8465,
 153                 'infin'    => 8734,
 154                 'int'      => 8747,
 155                 'Iota'     => 921,
 156                 'iota'     => 953,
 157                 'iquest'   => 191,
 158                 'isin'     => 8712,
 159                 'Iuml'     => 207,
 160                 'iuml'     => 239,
 161                 'Kappa'    => 922,
 162                 'kappa'    => 954,
 163                 'Lambda'   => 923,
 164                 'lambda'   => 955,
 165                 'lang'     => 9001,
 166                 'laquo'    => 171,
 167                 'larr'     => 8592,
 168                 'lArr'     => 8656,
 169                 'lceil'    => 8968,
 170                 'ldquo'    => 8220,
 171                 'le'       => 8804,
 172                 'lfloor'   => 8970,
 173                 'lowast'   => 8727,
 174                 'loz'      => 9674,
 175                 'lrm'      => 8206,
 176                 'lsaquo'   => 8249,
 177                 'lsquo'    => 8216,
 178                 'lt'       => 60,
 179                 'macr'     => 175,
 180                 'mdash'    => 8212,
 181                 'micro'    => 181,
 182                 'middot'   => 183,
 183                 'minus'    => 8722,
 184                 'Mu'       => 924,
 185                 'mu'       => 956,
 186                 'nabla'    => 8711,
 187                 'nbsp'     => 160,
 188                 'ndash'    => 8211,
 189                 'ne'       => 8800,
 190                 'ni'       => 8715,
 191                 'not'      => 172,
 192                 'notin'    => 8713,
 193                 'nsub'     => 8836,
 194                 'Ntilde'   => 209,
 195                 'ntilde'   => 241,
 196                 'Nu'       => 925,
 197                 'nu'       => 957,
 198                 'Oacute'   => 211,
 199                 'oacute'   => 243,
 200                 'Ocirc'    => 212,
 201                 'ocirc'    => 244,
 202                 'OElig'    => 338,
 203                 'oelig'    => 339,
 204                 'Ograve'   => 210,
 205                 'ograve'   => 242,
 206                 'oline'    => 8254,
 207                 'Omega'    => 937,
 208                 'omega'    => 969,
 209                 'Omicron'  => 927,
 210                 'omicron'  => 959,
 211                 'oplus'    => 8853,
 212                 'or'       => 8744,
 213                 'ordf'     => 170,
 214                 'ordm'     => 186,
 215                 'Oslash'   => 216,
 216                 'oslash'   => 248,
 217                 'Otilde'   => 213,
 218                 'otilde'   => 245,
 219                 'otimes'   => 8855,
 220                 'Ouml'     => 214,
 221                 'ouml'     => 246,
 222                 'para'     => 182,
 223                 'part'     => 8706,
 224                 'permil'   => 8240,
 225                 'perp'     => 8869,
 226                 'Phi'      => 934,
 227                 'phi'      => 966,
 228                 'Pi'       => 928,
 229                 'pi'       => 960,
 230                 'piv'      => 982,
 231                 'plusmn'   => 177,
 232                 'pound'    => 163,
 233                 'prime'    => 8242,
 234                 'Prime'    => 8243,
 235                 'prod'     => 8719,
 236                 'prop'     => 8733,
 237                 'Psi'      => 936,
 238                 'psi'      => 968,
 239                 'quot'     => 34,
 240                 'radic'    => 8730,
 241                 'rang'     => 9002,
 242                 'raquo'    => 187,
 243                 'rarr'     => 8594,
 244                 'rArr'     => 8658,
 245                 'rceil'    => 8969,
 246                 'rdquo'    => 8221,
 247                 'real'     => 8476,
 248                 'reg'      => 174,
 249                 'rfloor'   => 8971,
 250                 'Rho'      => 929,
 251                 'rho'      => 961,
 252                 'rlm'      => 8207,
 253                 'rsaquo'   => 8250,
 254                 'rsquo'    => 8217,
 255                 'sbquo'    => 8218,
 256                 'Scaron'   => 352,
 257                 'scaron'   => 353,
 258                 'sdot'     => 8901,
 259                 'sect'     => 167,
 260                 'shy'      => 173,
 261                 'Sigma'    => 931,
 262                 'sigma'    => 963,
 263                 'sigmaf'   => 962,
 264                 'sim'      => 8764,
 265                 'spades'   => 9824,
 266                 'sub'      => 8834,
 267                 'sube'     => 8838,
 268                 'sum'      => 8721,
 269                 'sup'      => 8835,
 270                 'sup1'     => 185,
 271                 'sup2'     => 178,
 272                 'sup3'     => 179,
 273                 'supe'     => 8839,
 274                 'szlig'    => 223,
 275                 'Tau'      => 932,
 276                 'tau'      => 964,
 277                 'there4'   => 8756,
 278                 'Theta'    => 920,
 279                 'theta'    => 952,
 280                 'thetasym' => 977,
 281                 'thinsp'   => 8201,
 282                 'THORN'    => 222,
 283                 'thorn'    => 254,
 284                 'tilde'    => 732,
 285                 'times'    => 215,
 286                 'trade'    => 8482,
 287                 'Uacute'   => 218,
 288                 'uacute'   => 250,
 289                 'uarr'     => 8593,
 290                 'uArr'     => 8657,
 291                 'Ucirc'    => 219,
 292                 'ucirc'    => 251,
 293                 'Ugrave'   => 217,
 294                 'ugrave'   => 249,
 295                 'uml'      => 168,
 296                 'upsih'    => 978,
 297                 'Upsilon'  => 933,
 298                 'upsilon'  => 965,
 299                 'Uuml'     => 220,
 300                 'uuml'     => 252,
 301                 'weierp'   => 8472,
 302                 'Xi'       => 926,
 303                 'xi'       => 958,
 304                 'Yacute'   => 221,
 305                 'yacute'   => 253,
 306                 'yen'      => 165,
 307                 'Yuml'     => 376,
 308                 'yuml'     => 255,
 309                 'Zeta'     => 918,
 310                 'zeta'     => 950,
 311                 'zwj'      => 8205,
 312                 'zwnj'     => 8204
 313         );
 314
 315         /**
 316          * Character entity aliases accepted by MediaWiki
 317          */
 318         static $htmlEntityAliases = array(
 319                 'רלמ' => 'rlm',
 320                 'رلم' => 'rlm',
 321         );
 322
 323         /**
 324          * Lazy-initialised attributes regex, see getAttribsRegex()
 325          */
 326         static $attribsRegex;
 327
 328         /**
 329          * Regular expression to match HTML/XML attribute pairs within a tag.
 330          * Allows some... latitude.
 331          * Used in Sanitizer::fixTagAttributes and Sanitizer::decodeTagAttributes
 332          */
 333         static function getAttribsRegex() {
 334                 if ( self::$attribsRegex === null ) {
 335                         $attribFirst = '[:A-Z_a-z0-9]';
 336                         $attrib = '[:A-Z_a-z-.0-9]';
 337                         $space = '[\x09\x0a\x0d\x20]';
 338                         self::$attribsRegex =
 339                                 "/(?:^|$space)({$attribFirst}{$attrib}*)
 340                                   ($space*=$space*
 341                                         (?:
 342                                          # The attribute value: quoted or alone
 343                                           \"([^<\"]*)\"
 344                                          | '([^<']*)'
 345                                          |  ([a-zA-Z0-9!#$%&()*,\\-.\\/:;<>?@[\\]^_`{|}~]+)
 346                                          |  (\#[0-9a-fA-F]+) # Technically wrong, but lots of
 347                                                                                  # colors are specified like this.
 348                                                                                  # We'll be normalizing it.
 349                                         )
 350                                 )?(?=$space|\$)/sx";
 351                 }
 352                 return self::$attribsRegex;
 353         }
 354
 355         /**
 356          * Cleans up HTML, removes dangerous tags and attributes, and
 357          * removes HTML comments
 358          * @private
 359          * @param $text String
 360          * @param $processCallback Callback to do any variable or parameter replacements in HTML attribute values
 361          * @param $args Array for the processing callback
 362          * @param $extratags Array for any extra tags to include
 363          * @param $removetags Array for any tags (default or extra) to exclude
 364          * @return string
 365          */
 366         static function removeHTMLtags( $text, $processCallback = null, $args = array(), $extratags = array(), $removetags = array() ) {
 367                 global $wgUseTidy, $wgHtml5, $wgAllowMicrodataAttributes, $wgAllowImageTag;
 368
 369                 static $htmlpairsStatic, $htmlsingle, $htmlsingleonly, $htmlnest, $tabletags,
 370                         $htmllist, $listtags, $htmlsingleallowed, $htmlelementsStatic, $staticInitialised;
 371
 372                 wfProfileIn( __METHOD__ );
 373
 374                 // Base our staticInitialised variable off of the global config state so that if the globals
 375                 // are changed (like in the secrewed up test system) we will re-initialise the settings.
 376                 $globalContext = implode( '-', compact( 'wgHtml5', 'wgAllowMicrodataAttributes', 'wgAllowImageTag' ) );
 377                 if ( !$staticInitialised || $staticInitialised != $globalContext ) {
 378
 379                         $htmlpairsStatic = array( # Tags that must be closed
 380                                 'b', 'del', 'i', 'ins', 'u', 'font', 'big', 'small', 'sub', 'sup', 'h1',
 381                                 'h2', 'h3', 'h4', 'h5', 'h6', 'cite', 'code', 'em', 's',
 382                                 'strike', 'strong', 'tt', 'var', 'div', 'center',
 383                                 'blockquote', 'ol', 'ul', 'dl', 'table', 'caption', 'pre',
 384                                 'ruby', 'rt' , 'rb' , 'rp', 'p', 'span', 'abbr', 'dfn',
 385                                 'kbd', 'samp'
 386                         );
 387                         if ( $wgHtml5 ) {
 388                                 $htmlpairsStatic = array_merge( $htmlpairsStatic, array( 'data', 'time' ) );
 389                         }
 390                         $htmlsingle = array(
 391                                 'br', 'hr', 'li', 'dt', 'dd'
 392                         );
 393                         $htmlsingleonly = array( # Elements that cannot have close tags
 394                                 'br', 'hr'
 395                         );
 396                         if ( $wgHtml5 && $wgAllowMicrodataAttributes ) {
 397                                 $htmlsingle[] = $htmlsingleonly[] = 'meta';
 398                                 $htmlsingle[] = $htmlsingleonly[] = 'link';
 399                         }
 400                         $htmlnest = array( # Tags that can be nested--??
 401                                 'table', 'tr', 'td', 'th', 'div', 'blockquote', 'ol', 'ul',
 402                                 'dl', 'font', 'big', 'small', 'sub', 'sup', 'span'
 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 $bits
 449                                 if( preg_match( '!^(/?)(\\w+)([^>]*?)(/{0,1}>)([^<]*)$!', $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 uncloseable elements
 518                                                         $brace = '/>';
 519                                                 } elseif ( isset( $htmlsingle[$t] ) ) {
 520                                                         # Hack to not close $htmlsingle tags
 521                                                         $brace = null;
 522                                                 } elseif ( isset( $tabletags[$t] )
 523                                                 && in_array( $t, $tagstack ) ) {
 524                                                         // New table tag but forgot to close the previous one
 525                                                         $text .= "</$t>";
 526                                                 } else {
 527                                                         if ( $t == 'table' ) {
 528                                                                 array_push( $tablestack, $tagstack );
 529                                                                 $tagstack = array();
 530                                                         }
 531                                                         array_push( $tagstack, $t );
 532                                                 }
 533
 534                                                 # Replace any variables or template parameters with
 535                                                 # plaintext results.
 536                                                 if( is_callable( $processCallback ) ) {
 537                                                         call_user_func_array( $processCallback, array( &$params, $args ) );
 538                                                 }
 539
 540                                                 if ( !Sanitizer::validateTag( $params, $t ) ) {
 541                                                         $badtag = true;
 542                                                 }
 543
 544                                                 # Strip non-approved attributes from the tag
 545                                                 $newparams = Sanitizer::fixTagAttributes( $params, $t );
 546                                         }
 547                                         if ( !$badtag ) {
 548                                                 $rest = str_replace( '>', '&gt;', $rest );
 549                                                 $close = ( $brace == '/>' && !$slash ) ? ' /' : '';
 550                                                 $text .= "<$slash$t$newparams$close>$rest";
 551                                                 continue;
 552                                         }
 553                                 }
 554                                 $text .= '&lt;' . str_replace( '>', '&gt;', $x);
 555                         }
 556                         # Close off any remaining tags
 557                         while ( is_array( $tagstack ) && ($t = array_pop( $tagstack )) ) {
 558                                 $text .= "</$t>\n";
 559                                 if ( $t == 'table' ) { $tagstack = array_pop( $tablestack ); }
 560                         }
 561                 } else {
 562                         # this might be possible using tidy itself
 563                         foreach ( $bits as $x ) {
 564                                 preg_match( '/^(\\/?)(\\w+)([^>]*?)(\\/{0,1}>)([^<]*)$/',
 565                                 $x, $regs );
 566                                 @list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
 567                                 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
 568                                         if( is_callable( $processCallback ) ) {
 569                                                 call_user_func_array( $processCallback, array( &$params, $args ) );
 570                                         }
 571                                         $newparams = Sanitizer::fixTagAttributes( $params, $t );
 572                                         $rest = str_replace( '>', '&gt;', $rest );
 573                                         $text .= "<$slash$t$newparams$brace$rest";
 574                                 } else {
 575                                         $text .= '&lt;' . str_replace( '>', '&gt;', $x);
 576                                 }
 577                         }
 578                 }
 579                 wfProfileOut( __METHOD__ );
 580                 return $text;
 581         }
 582
 583         /**
 584          * Remove '<!--', '-->', and everything between.
 585          * To avoid leaving blank lines, when a comment is both preceded
 586          * and followed by a newline (ignoring spaces), trim leading and
 587          * trailing spaces and one of the newlines.
 588          *
 589          * @private
 590          * @param $text String
 591          * @return string
 592          */
 593         static function removeHTMLcomments( $text ) {
 594                 wfProfileIn( __METHOD__ );
 595                 while (($start = strpos($text, '<!--')) !== false) {
 596                         $end = strpos($text, '-->', $start + 4);
 597                         if ($end === false) {
 598                                 # Unterminated comment; bail out
 599                                 break;
 600                         }
 601
 602                         $end += 3;
 603
 604                         # Trim space and newline if the comment is both
 605                         # preceded and followed by a newline
 606                         $spaceStart = max($start - 1, 0);
 607                         $spaceLen = $end - $spaceStart;
 608                         while (substr($text, $spaceStart, 1) === ' ' && $spaceStart > 0) {
 609                                 $spaceStart--;
 610                                 $spaceLen++;
 611                         }
 612                         while (substr($text, $spaceStart + $spaceLen, 1) === ' ')
 613                                 $spaceLen++;
 614                         if (substr($text, $spaceStart, 1) === "\n" and substr($text, $spaceStart + $spaceLen, 1) === "\n") {
 615                                 # Remove the comment, leading and trailing
 616                                 # spaces, and leave only one newline.
 617                                 $text = substr_replace($text, "\n", $spaceStart, $spaceLen + 1);
 618                         }
 619                         else {
 620                                 # Remove just the comment.
 621                                 $text = substr_replace($text, '', $start, $end - $start);
 622                         }
 623                 }
 624                 wfProfileOut( __METHOD__ );
 625                 return $text;
 626         }
 627
 628         /**
 629          * Take an array of attribute names and values and fix some deprecated values
 630          * for the given element type.
 631          * This does not validate properties, so you should ensure that you call
 632          * validateTagAttributes AFTER this to ensure that the resulting style rule
 633          * this may add is safe.
 634          *
 635          * - Converts most presentational attributes like align into inline css
 636          *
 637          * @param $attribs Array
 638          * @param $element String
 639          * @return Array
 640          */
 641         static function fixDeprecatedAttributes( $attribs, $element ) {
 642                 global $wgHtml5, $wgCleanupPresentationalAttributes;
 643
 644                 // presentational attributes were removed from html5, we can leave them
 645                 // in when html5 is turned off
 646                 if ( !$wgHtml5 || !$wgCleanupPresentationalAttributes ) {
 647                         return $attribs;
 648                 }
 649
 650                 $table = array( 'table' );
 651                 $cells = array( 'td', 'th' );
 652                 $colls = array( 'col', 'colgroup' );
 653                 $tblocks = array( 'tbody', 'tfoot', 'thead' );
 654                 $h = array( 'h1', 'h2', 'h3', 'h4', 'h5', 'h6' );
 655
 656                 $presentationalAttribs = array(
 657                         'align' => array( 'text-align', array_merge( array( 'caption', 'hr', 'div', 'p', 'tr' ), $table, $cells, $colls, $tblocks, $h ) ),
 658                         'clear' => array( 'clear', array( 'br' ) ),
 659                         'height' => array( 'height', $cells ),
 660                         'nowrap' => array( 'white-space', $cells ),
 661                         'size' => array( 'height', array( 'hr' ) ),
 662                         'type' => array( 'list-style-type', array( 'li', 'ol', 'ul' ) ),
 663                         'valign' => array( 'vertical-align', array_merge( $cells, $colls, $tblocks ) ),
 664                         'width' => array( 'width', array_merge( array( 'hr', 'pre' ), $table, $cells, $colls ) ),
 665                 );
 666
 667                 // Ensure that any upper case or mixed case attributes are converted to lowercase
 668                 foreach ( $attribs as $attribute => $value ) {
 669                         if ( $attribute !== strtolower( $attribute ) && array_key_exists( strtolower( $attribute ), $presentationalAttribs ) ) {
 670                                 $attribs[strtolower( $attribute )] = $value;
 671                                 unset( $attribs[$attribute] );
 672                         }
 673                 }
 674
 675                 $style = "";
 676                 foreach ( $presentationalAttribs as $attribute => $info ) {
 677                         list( $property, $elements ) = $info;
 678
 679                         // Skip if this attribute is not relevant to this element
 680                         if ( !in_array( $element, $elements ) ) {
 681                                 continue;
 682                         }
 683
 684                         // Skip if the attribute is not used
 685                         if ( !array_key_exists( $attribute, $attribs ) ) {
 686                                 continue;
 687                         }
 688
 689                         $value = $attribs[$attribute];
 690
 691                         // For nowrap the value should be nowrap instead of whatever text is in the value
 692                         if ( $attribute === 'nowrap' ) {
 693                                 $value = 'nowrap';
 694                         }
 695
 696                         // clear="all" is clear: both; in css
 697                         if ( $attribute === 'clear' && strtolower( $value ) === 'all' ) {
 698                                 $value = 'both';
 699                         }
 700
 701                         // Size based properties should have px applied to them if they have no unit
 702                         if ( in_array( $attribute, array( 'height', 'width', 'size' ) ) ) {
 703                                 if ( preg_match( '/^[\d.]+$/', $value ) ) {
 704                                         $value = "{$value}px";
 705                                 }
 706                         }
 707
 708                         $style .= " $property: $value;";
 709
 710                         unset( $attribs[$attribute] );
 711                 }
 712
 713                 if ( $style ) {
 714                         // Prepend our style rules so that they can be overridden by user css
 715                         if ( isset($attribs['style']) ) {
 716                                 $style .= " " . $attribs['style'];
 717                         }
 718                         $attribs['style'] = trim($style);
 719                 }
 720
 721                 return $attribs;
 722         }
 723
 724         /**
 725          * Takes attribute names and values for a tag and the tah name and
 726          * validates that the tag is allowed to be present.
 727          * This DOES NOT validate the attributes, nor does it validate the
 728          * tags themselves. This method only handles the special circumstances
 729          * where we may want to allow a tag within content but ONLY when it has
 730          * specific attributes set.
 731          *
 732          * @param $
 733          */
 734         static function validateTag( $params, $element ) {
 735                 $params = Sanitizer::decodeTagAttributes( $params );
 736
 737                 if ( $element == 'meta' || $element == 'link' ) {
 738                         if ( !isset( $params['itemprop'] ) ) {
 739                                 // <meta> and <link> must have an itemprop="" otherwise they are not valid or safe in content
 740                                 return false;
 741                         }
 742                         if ( $element == 'meta' && !isset( $params['content'] ) ) {
 743                                 // <meta> must have a content="" for the itemprop
 744                                 return false;
 745                         }
 746                         if ( $element == 'link' && !isset( $params['href'] ) ) {
 747                                 // <link> must have an associated href=""
 748                                 return false;
 749                         }
 750                 }
 751
 752                 return true;
 753         }
 754
 755         /**
 756          * Take an array of attribute names and values and normalize or discard
 757          * illegal values for the given element type.
 758          *
 759          * - Discards attributes not on a whitelist for the given element
 760          * - Unsafe style attributes are discarded
 761          * - Invalid id attributes are reencoded
 762          *
 763          * @param $attribs Array
 764          * @param $element String
 765          * @return Array
 766          *
 767          * @todo Check for legal values where the DTD limits things.
 768          * @todo Check for unique id attribute :P
 769          */
 770         static function validateTagAttributes( $attribs, $element ) {
 771                 return Sanitizer::validateAttributes( $attribs,
 772                         Sanitizer::attributeWhitelist( $element ) );
 773         }
 774
 775         /**
 776          * Take an array of attribute names and values and normalize or discard
 777          * illegal values for the given whitelist.
 778          *
 779          * - Discards attributes not the given whitelist
 780          * - Unsafe style attributes are discarded
 781          * - Invalid id attributes are reencoded
 782          *
 783          * @param $attribs Array
 784          * @param $whitelist Array: list of allowed attribute names
 785          * @return Array
 786          *
 787          * @todo Check for legal values where the DTD limits things.
 788          * @todo Check for unique id attribute :P
 789          */
 790         static function validateAttributes( $attribs, $whitelist ) {
 791                 global $wgAllowRdfaAttributes, $wgAllowMicrodataAttributes, $wgHtml5;
 792
 793                 $whitelist = array_flip( $whitelist );
 794                 $hrefExp = '/^(' . wfUrlProtocols() . ')[^\s]+$/';
 795
 796                 $out = array();
 797                 foreach( $attribs as $attribute => $value ) {
 798                         #allow XML namespace declaration if RDFa is enabled
 799                         if ( $wgAllowRdfaAttributes && preg_match( self::XMLNS_ATTRIBUTE_PATTERN, $attribute ) ) {
 800                                 if ( !preg_match( self::EVIL_URI_PATTERN, $value ) ) {
 801                                         $out[$attribute] = $value;
 802                                 }
 803
 804                                 continue;
 805                         }
 806
 807                         # Allow any attribute beginning with "data-", if in HTML5 mode
 808                         if ( !($wgHtml5 && preg_match( '/^data-/i', $attribute )) && !isset( $whitelist[$attribute] ) ) {
 809                                 continue;
 810                         }
 811
 812                         # Strip javascript "expression" from stylesheets.
 813                         # http://msdn.microsoft.com/workshop/author/dhtml/overview/recalc.asp
 814                         if( $attribute == 'style' ) {
 815                                 $value = Sanitizer::checkCss( $value );
 816                         }
 817
 818                         if ( $attribute === 'id' ) {
 819                                 $value = Sanitizer::escapeId( $value, 'noninitial' );
 820                         }
 821
 822                         //RDFa and microdata properties allow URLs, URIs and/or CURIs. check them for sanity
 823                         if ( $attribute === 'rel' || $attribute === 'rev' ||
 824                                 $attribute === 'about' || $attribute === 'property' || $attribute === 'resource' || #RDFa
 825                                 $attribute === 'datatype' || $attribute === 'typeof' ||                             #RDFa
 826                                 $attribute === 'itemid' || $attribute === 'itemprop' || $attribute === 'itemref' || #HTML5 microdata
 827                                 $attribute === 'itemscope' || $attribute === 'itemtype' ) {                         #HTML5 microdata
 828
 829                                 //Paranoia. Allow "simple" values but suppress javascript
 830                                 if ( preg_match( self::EVIL_URI_PATTERN, $value ) ) {
 831                                         continue;
 832                                 }
 833                         }
 834
 835                         # NOTE: even though elements using href/src are not allowed directly, supply
 836                         #       validation code that can be used by tag hook handlers, etc
 837                         if ( $attribute === 'href' || $attribute === 'src' ) {
 838                                 if ( !preg_match( $hrefExp, $value ) ) {
 839                                         continue; //drop any href or src attributes not using an allowed protocol.
 840                                                   //NOTE: this also drops all relative URLs
 841                                 }
 842                         }
 843
 844                         // If this attribute was previously set, override it.
 845                         // Output should only have one attribute of each name.
 846                         $out[$attribute] = $value;
 847                 }
 848
 849                 if ( $wgAllowMicrodataAttributes ) {
 850                         # itemtype, itemid, itemref don't make sense without itemscope
 851                         if ( !array_key_exists( 'itemscope', $out ) ) {
 852                                 unset( $out['itemtype'] );
 853                                 unset( $out['itemid'] );
 854                                 unset( $out['itemref'] );
 855                         }
 856                         # TODO: Strip itemprop if we aren't descendants of an itemscope or pointed to by an itemref.
 857                 }
 858                 return $out;
 859         }
 860
 861         /**
 862          * Merge two sets of HTML attributes.  Conflicting items in the second set
 863          * will override those in the first, except for 'class' attributes which
 864          * will be combined (if they're both strings).
 865          *
 866          * @todo implement merging for other attributes such as style
 867          * @param $a Array
 868          * @param $b Array
 869          * @return array
 870          */
 871         static function mergeAttributes( $a, $b ) {
 872                 $out = array_merge( $a, $b );
 873                 if( isset( $a['class'] ) && isset( $b['class'] )
 874                 && is_string( $a['class'] ) && is_string( $b['class'] )
 875                 && $a['class'] !== $b['class'] ) {
 876                         $classes = preg_split( '/\s+/', "{$a['class']} {$b['class']}",
 877                                 -1, PREG_SPLIT_NO_EMPTY );
 878                         $out['class'] = implode( ' ', array_unique( $classes ) );
 879                 }
 880                 return $out;
 881         }
 882
 883         /**
 884          * Pick apart some CSS and check it for forbidden or unsafe structures.
 885          * Returns a sanitized string. This sanitized string will have
 886          * character references and escape sequences decoded, and comments
 887          * stripped. If the input is just too evil, only a comment complaining
 888          * about evilness will be returned.
 889          *
 890          * Currently URL references, 'expression', 'tps' are forbidden.
 891          *
 892          * NOTE: Despite the fact that character references are decoded, the
 893          * returned string may contain character references given certain
 894          * clever input strings. These character references must
 895          * be escaped before the return value is embedded in HTML.
 896          *
 897          * @param $value String
 898          * @return String
 899          */
 900         static function checkCss( $value ) {
 901                 // Decode character references like &#123;
 902                 $value = Sanitizer::decodeCharReferences( $value );
 903
 904                 // Decode escape sequences and line continuation
 905                 // See the grammar in the CSS 2 spec, appendix D.
 906                 // This has to be done AFTER decoding character references.
 907                 // This means it isn't possible for this function to return
 908                 // unsanitized escape sequences. It is possible to manufacture
 909                 // input that contains character references that decode to
 910                 // escape sequences that decode to character references, but
 911                 // it's OK for the return value to contain character references
 912                 // because the caller is supposed to escape those anyway.
 913                 static $decodeRegex;
 914                 if ( !$decodeRegex ) {
 915                         $space = '[\\x20\\t\\r\\n\\f]';
 916                         $nl = '(?:\\n|\\r\\n|\\r|\\f)';
 917                         $backslash = '\\\\';
 918                         $decodeRegex = "/ $backslash
 919                                 (?:
 920                                         ($nl) |  # 1. Line continuation
 921                                         ([0-9A-Fa-f]{1,6})$space? |  # 2. character number
 922                                         (.) | # 3. backslash cancelling special meaning
 923                                         () | # 4. backslash at end of string
 924                                 )/xu";
 925                 }
 926                 $value = preg_replace_callback( $decodeRegex,
 927                         array( __CLASS__, 'cssDecodeCallback' ), $value );
 928
 929                 // Remove any comments; IE gets token splitting wrong
 930                 // This must be done AFTER decoding character references and
 931                 // escape sequences, because those steps can introduce comments
 932                 // This step cannot introduce character references or escape
 933                 // sequences, because it replaces comments with spaces rather
 934                 // than removing them completely.
 935                 $value = StringUtils::delimiterReplace( '/*', '*/', ' ', $value );
 936
 937                 // Remove anything after a comment-start token, to guard against
 938                 // incorrect client implementations.
 939                 $commentPos = strpos( $value, '/*' );
 940                 if ( $commentPos !== false ) {
 941                         $value = substr( $value, 0, $commentPos );
 942                 }
 943
 944                 // Reject problematic keywords and control characters
 945                 if ( preg_match( '/[\000-\010\016-\037\177]/', $value ) ) {
 946                         return '/* invalid control char */';
 947                 } elseif ( preg_match( '! expression | filter\s*: | accelerator\s*: | url\s*\( !ix', $value ) ) {
 948                         return '/* insecure input */';
 949                 }
 950                 return $value;
 951         }
 952
 953         /**
 954          * @param $matches array
 955          * @return String
 956          */
 957         static function cssDecodeCallback( $matches ) {
 958                 if ( $matches[1] !== '' ) {
 959                         // Line continuation
 960                         return '';
 961                 } elseif ( $matches[2] !== '' ) {
 962                         $char = codepointToUtf8( hexdec( $matches[2] ) );
 963                 } elseif ( $matches[3] !== '' ) {
 964                         $char = $matches[3];
 965                 } else {
 966                         $char = '\\';
 967                 }
 968                 if ( $char == "\n" || $char == '"' || $char == "'" || $char == '\\' ) {
 969                         // These characters need to be escaped in strings
 970                         // Clean up the escape sequence to avoid parsing errors by clients
 971                         return '\\' . dechex( ord( $char ) ) . ' ';
 972                 } else {
 973                         // Decode unnecessary escape
 974                         return $char;
 975                 }
 976         }
 977
 978         /**
 979          * Take a tag soup fragment listing an HTML element's attributes
 980          * and normalize it to well-formed XML, discarding unwanted attributes.
 981          * Output is safe for further wikitext processing, with escaping of
 982          * values that could trigger problems.
 983          *
 984          * - Normalizes attribute names to lowercase
 985          * - Discards attributes not on a whitelist for the given element
 986          * - Turns broken or invalid entities into plaintext
 987          * - Double-quotes all attribute values
 988          * - Attributes without values are given the name as attribute
 989          * - Double attributes are discarded
 990          * - Unsafe style attributes are discarded
 991          * - Prepends space if there are attributes.
 992          *
 993          * @param $text String
 994          * @param $element String
 995          * @return String
 996          */
 997         static function fixTagAttributes( $text, $element ) {
 998                 if( trim( $text ) == '' ) {
 999                         return '';
1000                 }
1001
1002                 $decoded = Sanitizer::decodeTagAttributes( $text );
1003                 $decoded = Sanitizer::fixDeprecatedAttributes( $decoded, $element );
1004                 $stripped = Sanitizer::validateTagAttributes( $decoded, $element );
1005
1006                 $attribs = array();
1007                 foreach( $stripped as $attribute => $value ) {
1008                         $encAttribute = htmlspecialchars( $attribute );
1009                         $encValue = Sanitizer::safeEncodeAttribute( $value );
1010
1011                         $attribs[] = "$encAttribute=\"$encValue\"";
1012                 }
1013                 return count( $attribs ) ? ' ' . implode( ' ', $attribs ) : '';
1014         }
1015
1016         /**
1017          * Encode an attribute value for HTML output.
1018          * @param $text String
1019          * @return HTML-encoded text fragment
1020          */
1021         static function encodeAttribute( $text ) {
1022                 $encValue = htmlspecialchars( $text, ENT_QUOTES );
1023
1024                 // Whitespace is normalized during attribute decoding,
1025                 // so if we've been passed non-spaces we must encode them
1026                 // ahead of time or they won't be preserved.
1027                 $encValue = strtr( $encValue, array(
1028                         "\n" => '&#10;',
1029                         "\r" => '&#13;',
1030                         "\t" => '&#9;',
1031                 ) );
1032
1033                 return $encValue;
1034         }
1035
1036         /**
1037          * Encode an attribute value for HTML tags, with extra armoring
1038          * against further wiki processing.
1039          * @param $text String
1040          * @return HTML-encoded text fragment
1041          */
1042         static function safeEncodeAttribute( $text ) {
1043                 $encValue = Sanitizer::encodeAttribute( $text );
1044
1045                 # Templates and links may be expanded in later parsing,
1046                 # creating invalid or dangerous output. Suppress this.
1047                 $encValue = strtr( $encValue, array(
1048                         '<'    => '&lt;',   // This should never happen,
1049                         '>'    => '&gt;',   // we've received invalid input
1050                         '"'    => '&quot;', // which should have been escaped.
1051                         '{'    => '&#123;',
1052                         '['    => '&#91;',
1053                         "''"   => '&#39;&#39;',
1054                         'ISBN' => '&#73;SBN',
1055                         'RFC'  => '&#82;FC',
1056                         'PMID' => '&#80;MID',
1057                         '|'    => '&#124;',
1058                         '__'   => '&#95;_',
1059                 ) );
1060
1061                 # Stupid hack
1062                 $encValue = preg_replace_callback(
1063                         '/(' . wfUrlProtocols() . ')/',
1064                         array( 'Sanitizer', 'armorLinksCallback' ),
1065                         $encValue );
1066                 return $encValue;
1067         }
1068
1069         /**
1070          * Given a value, escape it so that it can be used in an id attribute and
1071          * return it.  This will use HTML5 validation if $wgExperimentalHtmlIds is
1072          * true, allowing anything but ASCII whitespace.  Otherwise it will use
1073          * HTML 4 rules, which means a narrow subset of ASCII, with bad characters
1074          * escaped with lots of dots.
1075          *
1076          * To ensure we don't have to bother escaping anything, we also strip ', ",
1077          * & even if $wgExperimentalIds is true.  TODO: Is this the best tactic?
1078          * We also strip # because it upsets IE, and % because it could be
1079          * ambiguous if it's part of something that looks like a percent escape
1080          * (which don't work reliably in fragments cross-browser).
1081          *
1082          * @see http://www.w3.org/TR/html401/types.html#type-name Valid characters
1083          *                                                          in the id and
1084          *                                                          name attributes
1085          * @see http://www.w3.org/TR/html401/struct/links.html#h-12.2.3 Anchors with the id attribute
1086          * @see http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-id-attribute
1087          *   HTML5 definition of id attribute
1088          *
1089          * @param $id String: id to escape
1090          * @param $options Mixed: string or array of strings (default is array()):
1091          *   'noninitial': This is a non-initial fragment of an id, not a full id,
1092          *       so don't pay attention if the first character isn't valid at the
1093          *       beginning of an id.  Only matters if $wgExperimentalHtmlIds is
1094          *       false.
1095          *   'legacy': Behave the way the old HTML 4-based ID escaping worked even
1096          *       if $wgExperimentalHtmlIds is used, so we can generate extra
1097          *       anchors and links won't break.
1098          * @return String
1099          */
1100         static function escapeId( $id, $options = array() ) {
1101                 global $wgHtml5, $wgExperimentalHtmlIds;
1102                 $options = (array)$options;
1103
1104                 if ( $wgHtml5 && $wgExperimentalHtmlIds && !in_array( 'legacy', $options ) ) {
1105                         $id = Sanitizer::decodeCharReferences( $id );
1106                         $id = preg_replace( '/[ \t\n\r\f_\'"&#%]+/', '_', $id );
1107                         $id = trim( $id, '_' );
1108                         if ( $id === '' ) {
1109                                 # Must have been all whitespace to start with.
1110                                 return '_';
1111                         } else {
1112                                 return $id;
1113                         }
1114                 }
1115
1116                 # HTML4-style escaping
1117                 static $replace = array(
1118                         '%3A' => ':',
1119                         '%' => '.'
1120                 );
1121
1122                 $id = urlencode( Sanitizer::decodeCharReferences( strtr( $id, ' ', '_' ) ) );
1123                 $id = str_replace( array_keys( $replace ), array_values( $replace ), $id );
1124
1125                 if ( !preg_match( '/^[a-zA-Z]/', $id )
1126                 && !in_array( 'noninitial', $options ) )  {
1127                         // Initial character must be a letter!
1128                         $id = "x$id";
1129                 }
1130                 return $id;
1131         }
1132
1133         /**
1134          * Given a value, escape it so that it can be used as a CSS class and
1135          * return it.
1136          *
1137          * @todo For extra validity, input should be validated UTF-8.
1138          *
1139          * @see http://www.w3.org/TR/CSS21/syndata.html Valid characters/format
1140          *
1141          * @param $class String
1142          * @return String
1143          */
1144         static function escapeClass( $class ) {
1145                 // Convert ugly stuff to underscores and kill underscores in ugly places
1146                 return rtrim(preg_replace(
1147                         array('/(^[0-9\\-])|[\\x00-\\x20!"#$%&\'()*+,.\\/:;<=>?@[\\]^`{|}~]|\\xC2\\xA0/','/_+/'),
1148                         '_',
1149                         $class ), '_');
1150         }
1151
1152         /**
1153          * Given HTML input, escape with htmlspecialchars but un-escape entites.
1154          * This allows (generally harmless) entities like &#160; to survive.
1155          *
1156          * @param $html String to escape
1157          * @return String: escaped input
1158          */
1159         static function escapeHtmlAllowEntities( $html ) {
1160                 $html = Sanitizer::decodeCharReferences( $html );
1161                 # It seems wise to escape ' as well as ", as a matter of course.  Can't
1162                 # hurt.
1163                 $html = htmlspecialchars( $html, ENT_QUOTES );
1164                 return $html;
1165         }
1166
1167         /**
1168          * Regex replace callback for armoring links against further processing.
1169          * @param $matches Array
1170          * @return string
1171          */
1172         private static function armorLinksCallback( $matches ) {
1173                 return str_replace( ':', '&#58;', $matches[1] );
1174         }
1175
1176         /**
1177          * Return an associative array of attribute names and values from
1178          * a partial tag string. Attribute names are forces to lowercase,
1179          * character references are decoded to UTF-8 text.
1180          *
1181          * @param $text String
1182          * @return Array
1183          */
1184         public static function decodeTagAttributes( $text ) {
1185                 if( trim( $text ) == '' ) {
1186                         return array();
1187                 }
1188
1189                 $attribs = array();
1190                 $pairs = array();
1191                 if( !preg_match_all(
1192                         self::getAttribsRegex(),
1193                         $text,
1194                         $pairs,
1195                         PREG_SET_ORDER ) ) {
1196                         return $attribs;
1197                 }
1198
1199                 foreach( $pairs as $set ) {
1200                         $attribute = strtolower( $set[1] );
1201                         $value = Sanitizer::getTagAttributeCallback( $set );
1202
1203                         // Normalize whitespace
1204                         $value = preg_replace( '/[\t\r\n ]+/', ' ', $value );
1205                         $value = trim( $value );
1206
1207                         // Decode character references
1208                         $attribs[$attribute] = Sanitizer::decodeCharReferences( $value );
1209                 }
1210                 return $attribs;
1211         }
1212
1213         /**
1214          * Pick the appropriate attribute value from a match set from the
1215          * attribs regex matches.
1216          *
1217          * @param $set Array
1218          * @return String
1219          */
1220         private static function getTagAttributeCallback( $set ) {
1221                 if( isset( $set[6] ) ) {
1222                         # Illegal #XXXXXX color with no quotes.
1223                         return $set[6];
1224                 } elseif( isset( $set[5] ) ) {
1225                         # No quotes.
1226                         return $set[5];
1227                 } elseif( isset( $set[4] ) ) {
1228                         # Single-quoted
1229                         return $set[4];
1230                 } elseif( isset( $set[3] ) ) {
1231                         # Double-quoted
1232                         return $set[3];
1233                 } elseif( !isset( $set[2] ) ) {
1234                         # In XHTML, attributes must have a value.
1235                         # For 'reduced' form, return explicitly the attribute name here.
1236                         return $set[1];
1237                 } else {
1238                         throw new MWException( "Tag conditions not met. This should never happen and is a bug." );
1239                 }
1240         }
1241
1242         /**
1243          * Normalize whitespace and character references in an XML source-
1244          * encoded text for an attribute value.
1245          *
1246          * See http://www.w3.org/TR/REC-xml/#AVNormalize for background,
1247          * but note that we're not returning the value, but are returning
1248          * XML source fragments that will be slapped into output.
1249          *
1250          * @param $text String
1251          * @return String
1252          */
1253         private static function normalizeAttributeValue( $text ) {
1254                 return str_replace( '"', '&quot;',
1255                         self::normalizeWhitespace(
1256                                 Sanitizer::normalizeCharReferences( $text ) ) );
1257         }
1258
1259         /**
1260          * @param $text string
1261          * @return mixed
1262          */
1263         private static function normalizeWhitespace( $text ) {
1264                 return preg_replace(
1265                         '/\r\n|[\x20\x0d\x0a\x09]/',
1266                         ' ',
1267                         $text );
1268         }
1269
1270         /**
1271          * Normalizes whitespace in a section name, such as might be returned
1272          * by Parser::stripSectionName(), for use in the id's that are used for
1273          * section links.
1274          *
1275          * @param $section String
1276          * @return String
1277          */
1278         static function normalizeSectionNameWhitespace( $section ) {
1279                 return trim( preg_replace( '/[ _]+/', ' ', $section ) );
1280         }
1281
1282         /**
1283          * Ensure that any entities and character references are legal
1284          * for XML and XHTML specifically. Any stray bits will be
1285          * &amp;-escaped to result in a valid text fragment.
1286          *
1287          * a. named char refs can only be &lt; &gt; &amp; &quot;, others are
1288          *   numericized (this way we're well-formed even without a DTD)
1289          * b. any numeric char refs must be legal chars, not invalid or forbidden
1290          * c. use &#x, not &#X
1291          * d. fix or reject non-valid attributes
1292          *
1293          * @param $text String
1294          * @return String
1295          * @private
1296          */
1297         static function normalizeCharReferences( $text ) {
1298                 return preg_replace_callback(
1299                         self::CHAR_REFS_REGEX,
1300                         array( 'Sanitizer', 'normalizeCharReferencesCallback' ),
1301                         $text );
1302         }
1303         /**
1304          * @param $matches String
1305          * @return String
1306          */
1307         static function normalizeCharReferencesCallback( $matches ) {
1308                 $ret = null;
1309                 if( $matches[1] != '' ) {
1310                         $ret = Sanitizer::normalizeEntity( $matches[1] );
1311                 } elseif( $matches[2] != '' ) {
1312                         $ret = Sanitizer::decCharReference( $matches[2] );
1313                 } elseif( $matches[3] != ''  ) {
1314                         $ret = Sanitizer::hexCharReference( $matches[3] );
1315                 }
1316                 if( is_null( $ret ) ) {
1317                         return htmlspecialchars( $matches[0] );
1318                 } else {
1319                         return $ret;
1320                 }
1321         }
1322
1323         /**
1324          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1325          * return the equivalent numeric entity reference (except for the core &lt;
1326          * &gt; &amp; &quot;). If the entity is a MediaWiki-specific alias, returns
1327          * the HTML equivalent. Otherwise, returns HTML-escaped text of
1328          * pseudo-entity source (eg &amp;foo;)
1329          *
1330          * @param $name String
1331          * @return String
1332          */
1333         static function normalizeEntity( $name ) {
1334                 if ( isset( self::$htmlEntityAliases[$name] ) ) {
1335                         return '&' . self::$htmlEntityAliases[$name] . ';';
1336                 } elseif ( in_array( $name,
1337                 array( 'lt', 'gt', 'amp', 'quot' ) ) ) {
1338                         return "&$name;";
1339                 } elseif ( isset( self::$htmlEntities[$name] ) ) {
1340                         return '&#' . self::$htmlEntities[$name] . ';';
1341                 } else {
1342                         return "&amp;$name;";
1343                 }
1344         }
1345
1346         /**
1347          * @param $codepoint
1348          * @return null|string
1349          */
1350         static function decCharReference( $codepoint ) {
1351                 $point = intval( $codepoint );
1352                 if( Sanitizer::validateCodepoint( $point ) ) {
1353                         return sprintf( '&#%d;', $point );
1354                 } else {
1355                         return null;
1356                 }
1357         }
1358
1359         /**
1360          * @param $codepoint
1361          * @return null|string
1362          */
1363         static function hexCharReference( $codepoint ) {
1364                 $point = hexdec( $codepoint );
1365                 if( Sanitizer::validateCodepoint( $point ) ) {
1366                         return sprintf( '&#x%x;', $point );
1367                 } else {
1368                         return null;
1369                 }
1370         }
1371
1372         /**
1373          * Returns true if a given Unicode codepoint is a valid character in XML.
1374          * @param $codepoint Integer
1375          * @return Boolean
1376          */
1377         private static function validateCodepoint( $codepoint ) {
1378                 return ($codepoint ==    0x09)
1379                         || ($codepoint ==    0x0a)
1380                         || ($codepoint ==    0x0d)
1381                         || ($codepoint >=    0x20 && $codepoint <=   0xd7ff)
1382                         || ($codepoint >=  0xe000 && $codepoint <=   0xfffd)
1383                         || ($codepoint >= 0x10000 && $codepoint <= 0x10ffff);
1384         }
1385
1386         /**
1387          * Decode any character references, numeric or named entities,
1388          * in the text and return a UTF-8 string.
1389          *
1390          * @param $text String
1391          * @return String
1392          */
1393         public static function decodeCharReferences( $text ) {
1394                 return preg_replace_callback(
1395                         self::CHAR_REFS_REGEX,
1396                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1397                         $text );
1398         }
1399
1400         /**
1401          * Decode any character references, numeric or named entities,
1402          * in the next and normalize the resulting string. (bug 14952)
1403          *
1404          * This is useful for page titles, not for text to be displayed,
1405          * MediaWiki allows HTML entities to escape normalization as a feature.
1406          *
1407          * @param $text String (already normalized, containing entities)
1408          * @return String (still normalized, without entities)
1409          */
1410         public static function decodeCharReferencesAndNormalize( $text ) {
1411                 global $wgContLang;
1412                 $text = preg_replace_callback(
1413                         self::CHAR_REFS_REGEX,
1414                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1415                         $text, /* limit */ -1, $count );
1416
1417                 if ( $count ) {
1418                         return $wgContLang->normalize( $text );
1419                 } else {
1420                         return $text;
1421                 }
1422         }
1423
1424         /**
1425          * @param $matches String
1426          * @return String
1427          */
1428         static function decodeCharReferencesCallback( $matches ) {
1429                 if( $matches[1] != '' ) {
1430                         return Sanitizer::decodeEntity( $matches[1] );
1431                 } elseif( $matches[2] != '' ) {
1432                         return  Sanitizer::decodeChar( intval( $matches[2] ) );
1433                 } elseif( $matches[3] != ''  ) {
1434                         return  Sanitizer::decodeChar( hexdec( $matches[3] ) );
1435                 }
1436                 # Last case should be an ampersand by itself
1437                 return $matches[0];
1438         }
1439
1440         /**
1441          * Return UTF-8 string for a codepoint if that is a valid
1442          * character reference, otherwise U+FFFD REPLACEMENT CHARACTER.
1443          * @param $codepoint Integer
1444          * @return String
1445          * @private
1446          */
1447         static function decodeChar( $codepoint ) {
1448                 if( Sanitizer::validateCodepoint( $codepoint ) ) {
1449                         return codepointToUtf8( $codepoint );
1450                 } else {
1451                         return UTF8_REPLACEMENT;
1452                 }
1453         }
1454
1455         /**
1456          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1457          * return the UTF-8 encoding of that character. Otherwise, returns
1458          * pseudo-entity source (eg &foo;)
1459          *
1460          * @param $name String
1461          * @return String
1462          */
1463         static function decodeEntity( $name ) {
1464                 if ( isset( self::$htmlEntityAliases[$name] ) ) {
1465                         $name = self::$htmlEntityAliases[$name];
1466                 }
1467                 if( isset( self::$htmlEntities[$name] ) ) {
1468                         return codepointToUtf8( self::$htmlEntities[$name] );
1469                 } else {
1470                         return "&$name;";
1471                 }
1472         }
1473
1474         /**
1475          * Fetch the whitelist of acceptable attributes for a given element name.
1476          *
1477          * @param $element String
1478          * @return Array
1479          */
1480         static function attributeWhitelist( $element ) {
1481                 $list = Sanitizer::setupAttributeWhitelist();
1482                 return isset( $list[$element] )
1483                         ? $list[$element]
1484                         : array();
1485         }
1486
1487         /**
1488          * Foreach array key (an allowed HTML element), return an array
1489          * of allowed attributes
1490          * @return Array
1491          */
1492         static function setupAttributeWhitelist() {
1493                 global $wgAllowRdfaAttributes, $wgHtml5, $wgAllowMicrodataAttributes;
1494
1495                 static $whitelist, $staticInitialised;
1496                 $globalContext = implode( '-', compact( 'wgAllowRdfaAttributes', 'wgHtml5', 'wgAllowMicrodataAttributes' ) );
1497
1498                 if ( isset( $whitelist ) && $staticInitialised == $globalContext ) {
1499                         return $whitelist;
1500                 }
1501
1502                 $common = array( 'id', 'class', 'lang', 'dir', 'title', 'style' );
1503
1504                 if ( $wgAllowRdfaAttributes ) {
1505                         #RDFa attributes as specified in section 9 of http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014
1506                         $common = array_merge( $common, array(
1507                             'about', 'property', 'resource', 'datatype', 'typeof',
1508                         ) );
1509                 }
1510
1511                 if ( $wgHtml5 && $wgAllowMicrodataAttributes ) {
1512                         # add HTML5 microdata tages as pecified by http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#the-microdata-model
1513                         $common = array_merge( $common, array(
1514                             'itemid', 'itemprop', 'itemref', 'itemscope', 'itemtype'
1515                         ) );
1516                 }
1517
1518                 $block = array_merge( $common, array( 'align' ) );
1519                 $tablealign = array( 'align', 'char', 'charoff', 'valign' );
1520                 $tablecell = array( 'abbr',
1521                                     'axis',
1522                                     'headers',
1523                                     'scope',
1524                                     'rowspan',
1525                                     'colspan',
1526                                     'nowrap', # deprecated
1527                                     'width',  # deprecated
1528                                     'height', # deprecated
1529                                     'bgcolor' # deprecated
1530                                     );
1531
1532                 # Numbers refer to sections in HTML 4.01 standard describing the element.
1533                 # See: http://www.w3.org/TR/html4/
1534                 $whitelist = array(
1535                         # 7.5.4
1536                         'div'        => $block,
1537                         'center'     => $common, # deprecated
1538                         'span'       => $block, # ??
1539
1540                         # 7.5.5
1541                         'h1'         => $block,
1542                         'h2'         => $block,
1543                         'h3'         => $block,
1544                         'h4'         => $block,
1545                         'h5'         => $block,
1546                         'h6'         => $block,
1547
1548                         # 7.5.6
1549                         # address
1550
1551                         # 8.2.4
1552                         # bdo
1553
1554                         # 9.2.1
1555                         'em'         => $common,
1556                         'strong'     => $common,
1557                         'cite'       => $common,
1558                         'dfn'        => $common,
1559                         'code'       => $common,
1560                         'samp'       => $common,
1561                         'kbd'        => $common,
1562                         'var'        => $common,
1563                         'abbr'       => $common,
1564                         # acronym
1565
1566                         # 9.2.2
1567                         'blockquote' => array_merge( $common, array( 'cite' ) ),
1568                         # q
1569
1570                         # 9.2.3
1571                         'sub'        => $common,
1572                         'sup'        => $common,
1573
1574                         # 9.3.1
1575                         'p'          => $block,
1576
1577                         # 9.3.2
1578                         'br'         => array( 'id', 'class', 'title', 'style', 'clear' ),
1579
1580                         # 9.3.4
1581                         'pre'        => array_merge( $common, array( 'width' ) ),
1582
1583                         # 9.4
1584                         'ins'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1585                         'del'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1586
1587                         # 10.2
1588                         'ul'         => array_merge( $common, array( 'type' ) ),
1589                         'ol'         => array_merge( $common, array( 'type', 'start' ) ),
1590                         'li'         => array_merge( $common, array( 'type', 'value' ) ),
1591
1592                         # 10.3
1593                         'dl'         => $common,
1594                         'dd'         => $common,
1595                         'dt'         => $common,
1596
1597                         # 11.2.1
1598                         'table'      => array_merge( $common,
1599                                                                 array( 'summary', 'width', 'border', 'frame',
1600                                                                                 'rules', 'cellspacing', 'cellpadding',
1601                                                                                 'align', 'bgcolor',
1602                                                                 ) ),
1603
1604                         # 11.2.2
1605                         'caption'    => array_merge( $common, array( 'align' ) ),
1606
1607                         # 11.2.3
1608                         'thead'      => array_merge( $common, $tablealign ),
1609                         'tfoot'      => array_merge( $common, $tablealign ),
1610                         'tbody'      => array_merge( $common, $tablealign ),
1611
1612                         # 11.2.4
1613                         'colgroup'   => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1614                         'col'        => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1615
1616                         # 11.2.5
1617                         'tr'         => array_merge( $common, array( 'bgcolor' ), $tablealign ),
1618
1619                         # 11.2.6
1620                         'td'         => array_merge( $common, $tablecell, $tablealign ),
1621                         'th'         => array_merge( $common, $tablecell, $tablealign ),
1622
1623                         # 12.2 # NOTE: <a> is not allowed directly, but the attrib whitelist is used from the Parser object
1624                         'a'          => array_merge( $common, array( 'href', 'rel', 'rev' ) ), # rel/rev esp. for RDFa
1625
1626                         # 13.2
1627                         # Not usually allowed, but may be used for extension-style hooks
1628                         # such as <math> when it is rasterized, or if $wgAllowImageTag is
1629                         # true
1630                         'img'        => array_merge( $common, array( 'alt', 'src', 'width', 'height' ) ),
1631
1632                         # 15.2.1
1633                         'tt'         => $common,
1634                         'b'          => $common,
1635                         'i'          => $common,
1636                         'big'        => $common,
1637                         'small'      => $common,
1638                         'strike'     => $common,
1639                         's'          => $common,
1640                         'u'          => $common,
1641
1642                         # 15.2.2
1643                         'font'       => array_merge( $common, array( 'size', 'color', 'face' ) ),
1644                         # basefont
1645
1646                         # 15.3
1647                         'hr'         => array_merge( $common, array( 'noshade', 'size', 'width' ) ),
1648
1649                         # XHTML Ruby annotation text module, simple ruby only.
1650                         # http://www.w3c.org/TR/ruby/
1651                         'ruby'       => $common,
1652                         # rbc
1653                         # rtc
1654                         'rb'         => $common,
1655                         'rt'         => $common, #array_merge( $common, array( 'rbspan' ) ),
1656                         'rp'         => $common,
1657
1658                         # MathML root element, where used for extensions
1659                         # 'title' may not be 100% valid here; it's XHTML
1660                         # http://www.w3.org/TR/REC-MathML/
1661                         'math'       => array( 'class', 'style', 'id', 'title' ),
1662                 );
1663
1664                 if ( $wgHtml5 ) {
1665                         # HTML5 elements, defined by:
1666                         # http://www.whatwg.org/specs/web-apps/current-work/multipage/
1667                         $whitelist += array(
1668                                 'data' => array_merge( $common, array( 'value' ) ),
1669                                 'time' => array_merge( $common, array( 'datetime' ) ),
1670
1671                                 // meta and link are only present when Microdata is allowed anyways
1672                                 // so we don't bother adding another condition here
1673                                 // meta and link are only valid for use as Microdata so we do not
1674                                 // allow the common attributes here.
1675                                 'meta' => array( 'itemprop', 'content' ),
1676                                 'link' => array( 'itemprop', 'href' ),
1677                         );
1678                 }
1679
1680                 $staticInitialised = $globalContext;
1681
1682                 return $whitelist;
1683         }
1684
1685         /**
1686          * Take a fragment of (potentially invalid) HTML and return
1687          * a version with any tags removed, encoded as plain text.
1688          *
1689          * Warning: this return value must be further escaped for literal
1690          * inclusion in HTML output as of 1.10!
1691          *
1692          * @param $text String: HTML fragment
1693          * @return String
1694          */
1695         static function stripAllTags( $text ) {
1696                 # Actual <tags>
1697                 $text = StringUtils::delimiterReplace( '<', '>', '', $text );
1698
1699                 # Normalize &entities and whitespace
1700                 $text = self::decodeCharReferences( $text );
1701                 $text = self::normalizeWhitespace( $text );
1702
1703                 return $text;
1704         }
1705
1706         /**
1707          * Hack up a private DOCTYPE with HTML's standard entity declarations.
1708          * PHP 4 seemed to know these if you gave it an HTML doctype, but
1709          * PHP 5.1 doesn't.
1710          *
1711          * Use for passing XHTML fragments to PHP's XML parsing functions
1712          *
1713          * @return String
1714          */
1715         static function hackDocType() {
1716                 $out = "<!DOCTYPE html [\n";
1717                 foreach( self::$htmlEntities as $entity => $codepoint ) {
1718                         $out .= "<!ENTITY $entity \"&#$codepoint;\">";
1719                 }
1720                 $out .= "]>\n";
1721                 return $out;
1722         }
1723
1724         /**
1725          * @param $url string
1726          * @return mixed|string
1727          */
1728         static function cleanUrl( $url ) {
1729                 # Normalize any HTML entities in input. They will be
1730                 # re-escaped by makeExternalLink().
1731                 $url = Sanitizer::decodeCharReferences( $url );
1732
1733                 # Escape any control characters introduced by the above step
1734                 $url = preg_replace_callback( '/[\][<>"\\x00-\\x20\\x7F\|]/',
1735                         array( __CLASS__, 'cleanUrlCallback' ), $url );
1736
1737                 # Validate hostname portion
1738                 $matches = array();
1739                 if( preg_match( '!^([^:]+:)(//[^/]+)?(.*)$!iD', $url, $matches ) ) {
1740                         list( /* $whole */, $protocol, $host, $rest ) = $matches;
1741
1742                         // Characters that will be ignored in IDNs.
1743                         // http://tools.ietf.org/html/3454#section-3.1
1744                         // Strip them before further processing so blacklists and such work.
1745                         $strip = "/
1746                                 \\s|          # general whitespace
1747                                 \xc2\xad|     # 00ad SOFT HYPHEN
1748                                 \xe1\xa0\x86| # 1806 MONGOLIAN TODO SOFT HYPHEN
1749                                 \xe2\x80\x8b| # 200b ZERO WIDTH SPACE
1750                                 \xe2\x81\xa0| # 2060 WORD JOINER
1751                                 \xef\xbb\xbf| # feff ZERO WIDTH NO-BREAK SPACE
1752                                 \xcd\x8f|     # 034f COMBINING GRAPHEME JOINER
1753                                 \xe1\xa0\x8b| # 180b MONGOLIAN FREE VARIATION SELECTOR ONE
1754                                 \xe1\xa0\x8c| # 180c MONGOLIAN FREE VARIATION SELECTOR TWO
1755                                 \xe1\xa0\x8d| # 180d MONGOLIAN FREE VARIATION SELECTOR THREE
1756                                 \xe2\x80\x8c| # 200c ZERO WIDTH NON-JOINER
1757                                 \xe2\x80\x8d| # 200d ZERO WIDTH JOINER
1758                                 [\xef\xb8\x80-\xef\xb8\x8f] # fe00-fe0f VARIATION SELECTOR-1-16
1759                                 /xuD";
1760
1761                         $host = preg_replace( $strip, '', $host );
1762
1763                         // @todo FIXME: Validate hostnames here
1764
1765                         return $protocol . $host . $rest;
1766                 } else {
1767                         return $url;
1768                 }
1769         }
1770
1771         /**
1772          * @param $matches array
1773          * @return string
1774          */
1775         static function cleanUrlCallback( $matches ) {
1776                 return urlencode( $matches[0] );
1777         }
1778
1779         /**
1780          * Does a string look like an e-mail address?
1781          *
1782          * This validates an email address using an HTML5 specification found at:
1783          * http://www.whatwg.org/specs/web-apps/current-work/multipage/states-of-the-type-attribute.html#valid-e-mail-address
1784          * Which as of 2011-01-24 says:
1785          *
1786          *   A valid e-mail address is a string that matches the ABNF production
1787          *   1*( atext / "." ) "@" ldh-str *( "." ldh-str ) where atext is defined
1788          *   in RFC 5322 section 3.2.3, and ldh-str is defined in RFC 1034 section
1789          *   3.5.
1790          *
1791          * This function is an implementation of the specification as requested in
1792          * bug 22449.
1793          *
1794          * Client-side forms will use the same standard validation rules via JS or
1795          * HTML 5 validation; additional restrictions can be enforced server-side
1796          * by extensions via the 'isValidEmailAddr' hook.
1797          *
1798          * Note that this validation doesn't 100% match RFC 2822, but is believed
1799          * to be liberal enough for wide use. Some invalid addresses will still
1800          * pass validation here.
1801          *
1802          * @since 1.18
1803          *
1804          * @param $addr String E-mail address
1805          * @return Bool
1806          */
1807         public static function validateEmail( $addr ) {
1808                 $result = null;
1809                 if( !wfRunHooks( 'isValidEmailAddr', array( $addr, &$result ) ) ) {
1810                         return $result;
1811                 }
1812
1813                 // Please note strings below are enclosed in brackets [], this make the
1814                 // hyphen "-" a range indicator. Hence it is double backslashed below.
1815                 // See bug 26948
1816                 $rfc5322_atext   = "a-z0-9!#$%&'*+\\-\/=?^_`{|}~" ;
1817                 $rfc1034_ldh_str = "a-z0-9\\-" ;
1818
1819                 $HTML5_email_regexp = "/
1820                 ^                      # start of string
1821                 [$rfc5322_atext\\.]+    # user part which is liberal :p
1822                 @                      # 'apostrophe'
1823                 [$rfc1034_ldh_str]+       # First domain part
1824                 (\\.[$rfc1034_ldh_str]+)*  # Following part prefixed with a dot
1825                 $                      # End of string
1826                 /ix" ; // case Insensitive, eXtended
1827
1828                 return (bool) preg_match( $HTML5_email_regexp, $addr );
1829         }
1830 }