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  * Regular expression to match various types of character references in
  29  * Sanitizer::normalizeCharReferences and Sanitizer::decodeCharReferences
  30  */
  31 define( 'MW_CHAR_REFS_REGEX',
  32         '/&([A-Za-z0-9\x80-\xff]+);
  33          |&\#([0-9]+);
  34          |&\#[xX]([0-9A-Fa-f]+);
  35          |(&)/x' );
  36
  37 /**
  38  * Regular expression to match HTML/XML attribute pairs within a tag.
  39  * Allows some... latitude.
  40  * Used in Sanitizer::fixTagAttributes and Sanitizer::decodeTagAttributes
  41  */
  42 $attribFirst = '[:A-Z_a-z0-9]';
  43 $attrib = '[:A-Z_a-z-.0-9]';
  44 $space = '[\x09\x0a\x0d\x20]';
  45 define( 'MW_ATTRIBS_REGEX',
  46         "/(?:^|$space)({$attribFirst}{$attrib}*)
  47           ($space*=$space*
  48                 (?:
  49                  # The attribute value: quoted or alone
  50                   \"([^<\"]*)\"
  51                  | '([^<']*)'
  52                  |  ([a-zA-Z0-9!#$%&()*,\\-.\\/:;<>?@[\\]^_`{|}~]+)
  53                  |  (\#[0-9a-fA-F]+) # Technically wrong, but lots of
  54                                                          # colors are specified like this.
  55                                                          # We'll be normalizing it.
  56                 )
  57            )?(?=$space|\$)/sx" );
  58
  59 /**
  60  * Regular expression to match URIs that could trigger script execution
  61  */
  62 define( 'MW_EVIL_URI_PATTERN', '!(^|\s|\*/\s*)(javascript|vbscript)([^\w]|$)!i' );
  63
  64 /**
  65  * Regular expression to match namespace attributes
  66  */
  67 define( 'MW_XMLNS_ATTRIBUTE_PATTRN', "/^xmlns:$attrib+$/" );
  68
  69 /**
  70  * List of all named character entities defined in HTML 4.01
  71  * http://www.w3.org/TR/html4/sgml/entities.html
  72  * @private
  73  */
  74 global $wgHtmlEntities;
  75 $wgHtmlEntities = array(
  76         'Aacute'   => 193,
  77         'aacute'   => 225,
  78         'Acirc'    => 194,
  79         'acirc'    => 226,
  80         'acute'    => 180,
  81         'AElig'    => 198,
  82         'aelig'    => 230,
  83         'Agrave'   => 192,
  84         'agrave'   => 224,
  85         'alefsym'  => 8501,
  86         'Alpha'    => 913,
  87         'alpha'    => 945,
  88         'amp'      => 38,
  89         'and'      => 8743,
  90         'ang'      => 8736,
  91         'Aring'    => 197,
  92         'aring'    => 229,
  93         'asymp'    => 8776,
  94         'Atilde'   => 195,
  95         'atilde'   => 227,
  96         'Auml'     => 196,
  97         'auml'     => 228,
  98         'bdquo'    => 8222,
  99         'Beta'     => 914,
 100         'beta'     => 946,
 101         'brvbar'   => 166,
 102         'bull'     => 8226,
 103         'cap'      => 8745,
 104         'Ccedil'   => 199,
 105         'ccedil'   => 231,
 106         'cedil'    => 184,
 107         'cent'     => 162,
 108         'Chi'      => 935,
 109         'chi'      => 967,
 110         'circ'     => 710,
 111         'clubs'    => 9827,
 112         'cong'     => 8773,
 113         'copy'     => 169,
 114         'crarr'    => 8629,
 115         'cup'      => 8746,
 116         'curren'   => 164,
 117         'dagger'   => 8224,
 118         'Dagger'   => 8225,
 119         'darr'     => 8595,
 120         'dArr'     => 8659,
 121         'deg'      => 176,
 122         'Delta'    => 916,
 123         'delta'    => 948,
 124         'diams'    => 9830,
 125         'divide'   => 247,
 126         'Eacute'   => 201,
 127         'eacute'   => 233,
 128         'Ecirc'    => 202,
 129         'ecirc'    => 234,
 130         'Egrave'   => 200,
 131         'egrave'   => 232,
 132         'empty'    => 8709,
 133         'emsp'     => 8195,
 134         'ensp'     => 8194,
 135         'Epsilon'  => 917,
 136         'epsilon'  => 949,
 137         'equiv'    => 8801,
 138         'Eta'      => 919,
 139         'eta'      => 951,
 140         'ETH'      => 208,
 141         'eth'      => 240,
 142         'Euml'     => 203,
 143         'euml'     => 235,
 144         'euro'     => 8364,
 145         'exist'    => 8707,
 146         'fnof'     => 402,
 147         'forall'   => 8704,
 148         'frac12'   => 189,
 149         'frac14'   => 188,
 150         'frac34'   => 190,
 151         'frasl'    => 8260,
 152         'Gamma'    => 915,
 153         'gamma'    => 947,
 154         'ge'       => 8805,
 155         'gt'       => 62,
 156         'harr'     => 8596,
 157         'hArr'     => 8660,
 158         'hearts'   => 9829,
 159         'hellip'   => 8230,
 160         'Iacute'   => 205,
 161         'iacute'   => 237,
 162         'Icirc'    => 206,
 163         'icirc'    => 238,
 164         'iexcl'    => 161,
 165         'Igrave'   => 204,
 166         'igrave'   => 236,
 167         'image'    => 8465,
 168         'infin'    => 8734,
 169         'int'      => 8747,
 170         'Iota'     => 921,
 171         'iota'     => 953,
 172         'iquest'   => 191,
 173         'isin'     => 8712,
 174         'Iuml'     => 207,
 175         'iuml'     => 239,
 176         'Kappa'    => 922,
 177         'kappa'    => 954,
 178         'Lambda'   => 923,
 179         'lambda'   => 955,
 180         'lang'     => 9001,
 181         'laquo'    => 171,
 182         'larr'     => 8592,
 183         'lArr'     => 8656,
 184         'lceil'    => 8968,
 185         'ldquo'    => 8220,
 186         'le'       => 8804,
 187         'lfloor'   => 8970,
 188         'lowast'   => 8727,
 189         'loz'      => 9674,
 190         'lrm'      => 8206,
 191         'lsaquo'   => 8249,
 192         'lsquo'    => 8216,
 193         'lt'       => 60,
 194         'macr'     => 175,
 195         'mdash'    => 8212,
 196         'micro'    => 181,
 197         'middot'   => 183,
 198         'minus'    => 8722,
 199         'Mu'       => 924,
 200         'mu'       => 956,
 201         'nabla'    => 8711,
 202         'nbsp'     => 160,
 203         'ndash'    => 8211,
 204         'ne'       => 8800,
 205         'ni'       => 8715,
 206         'not'      => 172,
 207         'notin'    => 8713,
 208         'nsub'     => 8836,
 209         'Ntilde'   => 209,
 210         'ntilde'   => 241,
 211         'Nu'       => 925,
 212         'nu'       => 957,
 213         'Oacute'   => 211,
 214         'oacute'   => 243,
 215         'Ocirc'    => 212,
 216         'ocirc'    => 244,
 217         'OElig'    => 338,
 218         'oelig'    => 339,
 219         'Ograve'   => 210,
 220         'ograve'   => 242,
 221         'oline'    => 8254,
 222         'Omega'    => 937,
 223         'omega'    => 969,
 224         'Omicron'  => 927,
 225         'omicron'  => 959,
 226         'oplus'    => 8853,
 227         'or'       => 8744,
 228         'ordf'     => 170,
 229         'ordm'     => 186,
 230         'Oslash'   => 216,
 231         'oslash'   => 248,
 232         'Otilde'   => 213,
 233         'otilde'   => 245,
 234         'otimes'   => 8855,
 235         'Ouml'     => 214,
 236         'ouml'     => 246,
 237         'para'     => 182,
 238         'part'     => 8706,
 239         'permil'   => 8240,
 240         'perp'     => 8869,
 241         'Phi'      => 934,
 242         'phi'      => 966,
 243         'Pi'       => 928,
 244         'pi'       => 960,
 245         'piv'      => 982,
 246         'plusmn'   => 177,
 247         'pound'    => 163,
 248         'prime'    => 8242,
 249         'Prime'    => 8243,
 250         'prod'     => 8719,
 251         'prop'     => 8733,
 252         'Psi'      => 936,
 253         'psi'      => 968,
 254         'quot'     => 34,
 255         'radic'    => 8730,
 256         'rang'     => 9002,
 257         'raquo'    => 187,
 258         'rarr'     => 8594,
 259         'rArr'     => 8658,
 260         'rceil'    => 8969,
 261         'rdquo'    => 8221,
 262         'real'     => 8476,
 263         'reg'      => 174,
 264         'rfloor'   => 8971,
 265         'Rho'      => 929,
 266         'rho'      => 961,
 267         'rlm'      => 8207,
 268         'rsaquo'   => 8250,
 269         'rsquo'    => 8217,
 270         'sbquo'    => 8218,
 271         'Scaron'   => 352,
 272         'scaron'   => 353,
 273         'sdot'     => 8901,
 274         'sect'     => 167,
 275         'shy'      => 173,
 276         'Sigma'    => 931,
 277         'sigma'    => 963,
 278         'sigmaf'   => 962,
 279         'sim'      => 8764,
 280         'spades'   => 9824,
 281         'sub'      => 8834,
 282         'sube'     => 8838,
 283         'sum'      => 8721,
 284         'sup'      => 8835,
 285         'sup1'     => 185,
 286         'sup2'     => 178,
 287         'sup3'     => 179,
 288         'supe'     => 8839,
 289         'szlig'    => 223,
 290         'Tau'      => 932,
 291         'tau'      => 964,
 292         'there4'   => 8756,
 293         'Theta'    => 920,
 294         'theta'    => 952,
 295         'thetasym' => 977,
 296         'thinsp'   => 8201,
 297         'THORN'    => 222,
 298         'thorn'    => 254,
 299         'tilde'    => 732,
 300         'times'    => 215,
 301         'trade'    => 8482,
 302         'Uacute'   => 218,
 303         'uacute'   => 250,
 304         'uarr'     => 8593,
 305         'uArr'     => 8657,
 306         'Ucirc'    => 219,
 307         'ucirc'    => 251,
 308         'Ugrave'   => 217,
 309         'ugrave'   => 249,
 310         'uml'      => 168,
 311         'upsih'    => 978,
 312         'Upsilon'  => 933,
 313         'upsilon'  => 965,
 314         'Uuml'     => 220,
 315         'uuml'     => 252,
 316         'weierp'   => 8472,
 317         'Xi'       => 926,
 318         'xi'       => 958,
 319         'Yacute'   => 221,
 320         'yacute'   => 253,
 321         'yen'      => 165,
 322         'Yuml'     => 376,
 323         'yuml'     => 255,
 324         'Zeta'     => 918,
 325         'zeta'     => 950,
 326         'zwj'      => 8205,
 327         'zwnj'     => 8204 );
 328
 329 /**
 330  * Character entity aliases accepted by MediaWiki
 331  */
 332 global $wgHtmlEntityAliases;
 333 $wgHtmlEntityAliases = array(
 334         'רלמ' => 'rlm',
 335         'رلم' => 'rlm',
 336 );
 337
 338
 339 /**
 340  * XHTML sanitizer for MediaWiki
 341  * @ingroup Parser
 342  */
 343 class Sanitizer {
 344         /**
 345          * Cleans up HTML, removes dangerous tags and attributes, and
 346          * removes HTML comments
 347          * @private
 348          * @param $text String
 349          * @param $processCallback Callback to do any variable or parameter replacements in HTML attribute values
 350          * @param $args Array for the processing callback
 351          * @param $extratags Array for any extra tags to include
 352          * @param $removetags Array for any tags (default or extra) to exclude
 353          * @return string
 354          */
 355         static function removeHTMLtags( $text, $processCallback = null, $args = array(), $extratags = array(), $removetags = array() ) {
 356                 global $wgUseTidy;
 357
 358                 static $htmlpairsStatic, $htmlsingle, $htmlsingleonly, $htmlnest, $tabletags,
 359                         $htmllist, $listtags, $htmlsingleallowed, $htmlelementsStatic, $staticInitialised;
 360
 361                 wfProfileIn( __METHOD__ );
 362
 363                 if ( !$staticInitialised ) {
 364
 365                         $htmlpairsStatic = array( # Tags that must be closed
 366                                 'b', 'del', 'i', 'ins', 'u', 'font', 'big', 'small', 'sub', 'sup', 'h1',
 367                                 'h2', 'h3', 'h4', 'h5', 'h6', 'cite', 'code', 'em', 's',
 368                                 'strike', 'strong', 'tt', 'var', 'div', 'center',
 369                                 'blockquote', 'ol', 'ul', 'dl', 'table', 'caption', 'pre',
 370                                 'ruby', 'rt' , 'rb' , 'rp', 'p', 'span', 'abbr', 'dfn',
 371                                 'kbd', 'samp'
 372                         );
 373                         $htmlsingle = array(
 374                                 'br', 'hr', 'li', 'dt', 'dd'
 375                         );
 376                         $htmlsingleonly = array( # Elements that cannot have close tags
 377                                 'br', 'hr'
 378                         );
 379                         $htmlnest = array( # Tags that can be nested--??
 380                                 'table', 'tr', 'td', 'th', 'div', 'blockquote', 'ol', 'ul',
 381                                 'dl', 'font', 'big', 'small', 'sub', 'sup', 'span'
 382                         );
 383                         $tabletags = array( # Can only appear inside table, we will close them
 384                                 'td', 'th', 'tr',
 385                         );
 386                         $htmllist = array( # Tags used by list
 387                                 'ul','ol',
 388                         );
 389                         $listtags = array( # Tags that can appear in a list
 390                                 'li',
 391                         );
 392
 393                         global $wgAllowImageTag;
 394                         if ( $wgAllowImageTag ) {
 395                                 $htmlsingle[] = 'img';
 396                                 $htmlsingleonly[] = 'img';
 397                         }
 398
 399                         $htmlsingleallowed = array_unique( array_merge( $htmlsingle, $tabletags ) );
 400                         $htmlelementsStatic = array_unique( array_merge( $htmlsingle, $htmlpairsStatic, $htmlnest ) );
 401
 402                         # Convert them all to hashtables for faster lookup
 403                         $vars = array( 'htmlpairsStatic', 'htmlsingle', 'htmlsingleonly', 'htmlnest', 'tabletags',
 404                                 'htmllist', 'listtags', 'htmlsingleallowed', 'htmlelementsStatic' );
 405                         foreach ( $vars as $var ) {
 406                                 $$var = array_flip( $$var );
 407                         }
 408                         $staticInitialised = true;
 409                 }
 410                 # Populate $htmlpairs and $htmlelements with the $extratags and $removetags arrays
 411                 $extratags = array_flip( $extratags );
 412                 $removetags = array_flip( $removetags );
 413                 $htmlpairs = array_merge( $extratags, $htmlpairsStatic );
 414                 $htmlelements = array_diff_key( array_merge( $extratags, $htmlelementsStatic ) , $removetags );
 415
 416                 # Remove HTML comments
 417                 $text = Sanitizer::removeHTMLcomments( $text );
 418                 $bits = explode( '<', $text );
 419                 $text = str_replace( '>', '&gt;', array_shift( $bits ) );
 420                 if ( !$wgUseTidy ) {
 421                         $tagstack = $tablestack = array();
 422                         foreach ( $bits as $x ) {
 423                                 $regs = array();
 424                                 # $slash: Does the current element start with a '/'?
 425                                 # $t: Current element name
 426                                 # $params: String between element name and >
 427                                 # $brace: Ending '>' or '/>'
 428                                 # $rest: Everything until the next element of $bits
 429                                 if( preg_match( '!^(/?)(\\w+)([^>]*?)(/{0,1}>)([^<]*)$!', $x, $regs ) ) {
 430                                         list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
 431                                 } else {
 432                                         $slash = $t = $params = $brace = $rest = null;
 433                                 }
 434
 435                                 $badtag = false;
 436                                 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
 437                                         # Check our stack
 438                                         if ( $slash && isset( $htmlsingleonly[$t] ) ) {
 439                                                 $badtag = true;
 440                                         } elseif ( $slash ) {
 441                                                 # Closing a tag... is it the one we just opened?
 442                                                 $ot = @array_pop( $tagstack );
 443                                                 if ( $ot != $t ) {
 444                                                         if ( isset( $htmlsingleallowed[$ot] ) ) {
 445                                                                 # Pop all elements with an optional close tag
 446                                                                 # and see if we find a match below them
 447                                                                 $optstack = array();
 448                                                                 array_push( $optstack, $ot );
 449                                                                 $ot = @array_pop( $tagstack );
 450                                                                 while ( $ot != $t && isset( $htmlsingleallowed[$ot] ) ) {
 451                                                                         array_push( $optstack, $ot );
 452                                                                         $ot = @array_pop( $tagstack );
 453                                                                 }
 454                                                                 if ( $t != $ot ) {
 455                                                                         # No match. Push the optional elements back again
 456                                                                         $badtag = true;
 457                                                                         while ( $ot = @array_pop( $optstack ) ) {
 458                                                                                 array_push( $tagstack, $ot );
 459                                                                         }
 460                                                                 }
 461                                                         } else {
 462                                                                 @array_push( $tagstack, $ot );
 463                                                                 # <li> can be nested in <ul> or <ol>, skip those cases:
 464                                                                 if ( !isset( $htmllist[$ot] ) || !isset( $listtags[$t] ) ) {
 465                                                                         $badtag = true;
 466                                                                 }
 467                                                         }
 468                                                 } else {
 469                                                         if ( $t == 'table' ) {
 470                                                                 $tagstack = array_pop( $tablestack );
 471                                                         }
 472                                                 }
 473                                                 $newparams = '';
 474                                         } else {
 475                                                 # Keep track for later
 476                                                 if ( isset( $tabletags[$t] ) &&
 477                                                 !in_array( 'table', $tagstack ) ) {
 478                                                         $badtag = true;
 479                                                 } elseif ( in_array( $t, $tagstack ) &&
 480                                                 !isset( $htmlnest [$t ] ) ) {
 481                                                         $badtag = true;
 482                                                 # Is it a self closed htmlpair ? (bug 5487)
 483                                                 } elseif ( $brace == '/>' &&
 484                                                 isset( $htmlpairs[$t] ) ) {
 485                                                         $badtag = true;
 486                                                 } elseif ( isset( $htmlsingleonly[$t] ) ) {
 487                                                         # Hack to force empty tag for uncloseable elements
 488                                                         $brace = '/>';
 489                                                 } elseif ( isset( $htmlsingle[$t] ) ) {
 490                                                         # Hack to not close $htmlsingle tags
 491                                                         $brace = null;
 492                                                 } elseif ( isset( $tabletags[$t] )
 493                                                 && in_array( $t, $tagstack ) ) {
 494                                                         // New table tag but forgot to close the previous one
 495                                                         $text .= "</$t>";
 496                                                 } else {
 497                                                         if ( $t == 'table' ) {
 498                                                                 array_push( $tablestack, $tagstack );
 499                                                                 $tagstack = array();
 500                                                         }
 501                                                         array_push( $tagstack, $t );
 502                                                 }
 503
 504                                                 # Replace any variables or template parameters with
 505                                                 # plaintext results.
 506                                                 if( is_callable( $processCallback ) ) {
 507                                                         call_user_func_array( $processCallback, array( &$params, $args ) );
 508                                                 }
 509
 510                                                 # Strip non-approved attributes from the tag
 511                                                 $newparams = Sanitizer::fixTagAttributes( $params, $t );
 512                                         }
 513                                         if ( !$badtag ) {
 514                                                 $rest = str_replace( '>', '&gt;', $rest );
 515                                                 $close = ( $brace == '/>' && !$slash ) ? ' /' : '';
 516                                                 $text .= "<$slash$t$newparams$close>$rest";
 517                                                 continue;
 518                                         }
 519                                 }
 520                                 $text .= '&lt;' . str_replace( '>', '&gt;', $x);
 521                         }
 522                         # Close off any remaining tags
 523                         while ( is_array( $tagstack ) && ($t = array_pop( $tagstack )) ) {
 524                                 $text .= "</$t>\n";
 525                                 if ( $t == 'table' ) { $tagstack = array_pop( $tablestack ); }
 526                         }
 527                 } else {
 528                         # this might be possible using tidy itself
 529                         foreach ( $bits as $x ) {
 530                                 preg_match( '/^(\\/?)(\\w+)([^>]*?)(\\/{0,1}>)([^<]*)$/',
 531                                 $x, $regs );
 532                                 @list( /* $qbar */, $slash, $t, $params, $brace, $rest ) = $regs;
 533                                 if ( isset( $htmlelements[$t = strtolower( $t )] ) ) {
 534                                         if( is_callable( $processCallback ) ) {
 535                                                 call_user_func_array( $processCallback, array( &$params, $args ) );
 536                                         }
 537                                         $newparams = Sanitizer::fixTagAttributes( $params, $t );
 538                                         $rest = str_replace( '>', '&gt;', $rest );
 539                                         $text .= "<$slash$t$newparams$brace$rest";
 540                                 } else {
 541                                         $text .= '&lt;' . str_replace( '>', '&gt;', $x);
 542                                 }
 543                         }
 544                 }
 545                 wfProfileOut( __METHOD__ );
 546                 return $text;
 547         }
 548
 549         /**
 550          * Remove '<!--', '-->', and everything between.
 551          * To avoid leaving blank lines, when a comment is both preceded
 552          * and followed by a newline (ignoring spaces), trim leading and
 553          * trailing spaces and one of the newlines.
 554          *
 555          * @private
 556          * @param $text String
 557          * @return string
 558          */
 559         static function removeHTMLcomments( $text ) {
 560                 wfProfileIn( __METHOD__ );
 561                 while (($start = strpos($text, '<!--')) !== false) {
 562                         $end = strpos($text, '-->', $start + 4);
 563                         if ($end === false) {
 564                                 # Unterminated comment; bail out
 565                                 break;
 566                         }
 567
 568                         $end += 3;
 569
 570                         # Trim space and newline if the comment is both
 571                         # preceded and followed by a newline
 572                         $spaceStart = max($start - 1, 0);
 573                         $spaceLen = $end - $spaceStart;
 574                         while (substr($text, $spaceStart, 1) === ' ' && $spaceStart > 0) {
 575                                 $spaceStart--;
 576                                 $spaceLen++;
 577                         }
 578                         while (substr($text, $spaceStart + $spaceLen, 1) === ' ')
 579                                 $spaceLen++;
 580                         if (substr($text, $spaceStart, 1) === "\n" and substr($text, $spaceStart + $spaceLen, 1) === "\n") {
 581                                 # Remove the comment, leading and trailing
 582                                 # spaces, and leave only one newline.
 583                                 $text = substr_replace($text, "\n", $spaceStart, $spaceLen + 1);
 584                         }
 585                         else {
 586                                 # Remove just the comment.
 587                                 $text = substr_replace($text, '', $start, $end - $start);
 588                         }
 589                 }
 590                 wfProfileOut( __METHOD__ );
 591                 return $text;
 592         }
 593
 594         /**
 595          * Take an array of attribute names and values and normalize or discard
 596          * illegal values for the given element type.
 597          *
 598          * - Discards attributes not on a whitelist for the given element
 599          * - Unsafe style attributes are discarded
 600          * - Invalid id attributes are reencoded
 601          *
 602          * @param $attribs Array
 603          * @param $element String
 604          * @return Array
 605          *
 606          * @todo Check for legal values where the DTD limits things.
 607          * @todo Check for unique id attribute :P
 608          */
 609         static function validateTagAttributes( $attribs, $element ) {
 610                 return Sanitizer::validateAttributes( $attribs,
 611                         Sanitizer::attributeWhitelist( $element ) );
 612         }
 613
 614         /**
 615          * Take an array of attribute names and values and normalize or discard
 616          * illegal values for the given whitelist.
 617          *
 618          * - Discards attributes not the given whitelist
 619          * - Unsafe style attributes are discarded
 620          * - Invalid id attributes are reencoded
 621          *
 622          * @param $attribs Array
 623          * @param $whitelist Array: list of allowed attribute names
 624          * @return Array
 625          *
 626          * @todo Check for legal values where the DTD limits things.
 627          * @todo Check for unique id attribute :P
 628          */
 629         static function validateAttributes( $attribs, $whitelist ) {
 630                 global $wgAllowRdfaAttributes, $wgAllowMicrodataAttributes, $wgHtml5;
 631
 632                 $whitelist = array_flip( $whitelist );
 633                 $hrefExp = '/^(' . wfUrlProtocols() . ')[^\s]+$/';
 634
 635                 $out = array();
 636                 foreach( $attribs as $attribute => $value ) {
 637                         #allow XML namespace declaration if RDFa is enabled
 638                         if ( $wgAllowRdfaAttributes && preg_match( MW_XMLNS_ATTRIBUTE_PATTRN, $attribute ) ) {
 639                                 if ( !preg_match( MW_EVIL_URI_PATTERN, $value ) ) {
 640                                         $out[$attribute] = $value;
 641                                 }
 642
 643                                 continue;
 644                         }
 645
 646                         # Allow any attribute beginning with "data-", if in HTML5 mode
 647                         if ( !($wgHtml5 && preg_match( '/^data-/i', $attribute )) && !isset( $whitelist[$attribute] ) ) {
 648                                 continue;
 649                         }
 650
 651                         # Strip javascript "expression" from stylesheets.
 652                         # http://msdn.microsoft.com/workshop/author/dhtml/overview/recalc.asp
 653                         if( $attribute == 'style' ) {
 654                                 $value = Sanitizer::checkCss( $value );
 655                         }
 656
 657                         if ( $attribute === 'id' ) {
 658                                 $value = Sanitizer::escapeId( $value, 'noninitial' );
 659                         }
 660
 661                         //RDFa and microdata properties allow URLs, URIs and/or CURIs. check them for sanity
 662                         if ( $attribute === 'rel' || $attribute === 'rev' ||
 663                                 $attribute === 'about' || $attribute === 'property' || $attribute === 'resource' || #RDFa
 664                                 $attribute === 'datatype' || $attribute === 'typeof' ||                             #RDFa
 665                                 $attribute === 'itemid' || $attribute === 'itemprop' || $attribute === 'itemref' || #HTML5 microdata
 666                                 $attribute === 'itemscope' || $attribute === 'itemtype' ) {                         #HTML5 microdata
 667
 668                                 //Paranoia. Allow "simple" values but suppress javascript
 669                                 if ( preg_match( MW_EVIL_URI_PATTERN, $value ) ) {
 670                                         continue;
 671                                 }
 672                         }
 673
 674                         # NOTE: even though elements using href/src are not allowed directly, supply
 675                         #       validation code that can be used by tag hook handlers, etc
 676                         if ( $attribute === 'href' || $attribute === 'src' ) {
 677                                 if ( !preg_match( $hrefExp, $value ) ) {
 678                                         continue; //drop any href or src attributes not using an allowed protocol.
 679                                                   //NOTE: this also drops all relative URLs
 680                                 }
 681                         }
 682
 683                         // If this attribute was previously set, override it.
 684                         // Output should only have one attribute of each name.
 685                         $out[$attribute] = $value;
 686                 }
 687
 688                 if ( $wgAllowMicrodataAttributes ) {
 689                         # There are some complicated validity constraints we need to
 690                         # enforce here.  First of all, we don't want to allow non-standard
 691                         # itemtypes.
 692                         $allowedTypes = array(
 693                                 'http://microformats.org/profile/hcard',
 694                                 'http://microformats.org/profile/hcalendar#vevent',
 695                                 'http://n.whatwg.org/work',
 696                         );
 697                         if ( isset( $out['itemtype'] ) && !in_array( $out['itemtype'],
 698                         $allowedTypes ) ) {
 699                                 # Kill everything
 700                                 unset( $out['itemscope'] );
 701                         }
 702                         # itemtype, itemid, itemref don't make sense without itemscope
 703                         if ( !array_key_exists( 'itemscope', $out ) ) {
 704                                 unset( $out['itemtype'] );
 705                                 unset( $out['itemid'] );
 706                                 unset( $out['itemref'] );
 707                         }
 708                         # TODO: Strip itemprop if we aren't descendants of an itemscope.
 709                 }
 710                 return $out;
 711         }
 712
 713         /**
 714          * Merge two sets of HTML attributes.  Conflicting items in the second set
 715          * will override those in the first, except for 'class' attributes which
 716          * will be combined (if they're both strings).
 717          *
 718          * @todo implement merging for other attributes such as style
 719          * @param $a Array
 720          * @param $b Array
 721          * @return array
 722          */
 723         static function mergeAttributes( $a, $b ) {
 724                 $out = array_merge( $a, $b );
 725                 if( isset( $a['class'] ) && isset( $b['class'] )
 726                 && is_string( $a['class'] ) && is_string( $b['class'] )
 727                 && $a['class'] !== $b['class'] ) {
 728                         $classes = preg_split( '/\s+/', "{$a['class']} {$b['class']}",
 729                                 -1, PREG_SPLIT_NO_EMPTY );
 730                         $out['class'] = implode( ' ', array_unique( $classes ) );
 731                 }
 732                 return $out;
 733         }
 734
 735         /**
 736          * Pick apart some CSS and check it for forbidden or unsafe structures.
 737          * Returns a sanitized string, or false if it was just too evil.
 738          *
 739          * Currently URL references, 'expression', 'tps' are forbidden.
 740          *
 741          * @param $value String
 742          * @return Mixed
 743          */
 744         static function checkCss( $value ) {
 745                 $value = Sanitizer::decodeCharReferences( $value );
 746
 747                 // Remove any comments; IE gets token splitting wrong
 748                 $value = StringUtils::delimiterReplace( '/*', '*/', ' ', $value );
 749
 750                 // Remove anything after a comment-start token, to guard against
 751                 // incorrect client implementations.
 752                 $commentPos = strpos( $value, '/*' );
 753                 if ( $commentPos !== false ) {
 754                         $value = substr( $value, 0, $commentPos );
 755                 }
 756
 757                 // Decode escape sequences and line continuation
 758                 // See the grammar in the CSS 2 spec, appendix D.
 759                 static $decodeRegex;
 760                 if ( !$decodeRegex ) {
 761                         $space = '[\\x20\\t\\r\\n\\f]';
 762                         $nl = '(?:\\n|\\r\\n|\\r|\\f)';
 763                         $backslash = '\\\\';
 764                         $decodeRegex = "/ $backslash
 765                                 (?:
 766                                         ($nl) |  # 1. Line continuation
 767                                         ([0-9A-Fa-f]{1,6})$space? |  # 2. character number
 768                                         (.) | # 3. backslash cancelling special meaning
 769                                         () | # 4. backslash at end of string
 770                                 )/xu";
 771                 }
 772                 $value = preg_replace_callback( $decodeRegex,
 773                         array( __CLASS__, 'cssDecodeCallback' ), $value );
 774
 775                 // Reject problematic keywords and control characters
 776                 if ( preg_match( '/[\000-\010\016-\037\177]/', $value ) ) {
 777                         return '/* invalid control char */';
 778                 } elseif ( preg_match( '! expression | filter\s*: | accelerator\s*: | url\s*\( !ix', $value ) ) {
 779                         return '/* insecure input */';
 780                 }
 781                 return $value;
 782         }
 783
 784         static function cssDecodeCallback( $matches ) {
 785                 if ( $matches[1] !== '' ) {
 786                         // Line continuation
 787                         return '';
 788                 } elseif ( $matches[2] !== '' ) {
 789                         $char = codepointToUtf8( hexdec( $matches[2] ) );
 790                 } elseif ( $matches[3] !== '' ) {
 791                         $char = $matches[3];
 792                 } else {
 793                         $char = '\\';
 794                 }
 795                 if ( $char == "\n" || $char == '"' || $char == "'" || $char == '\\' ) {
 796                         // These characters need to be escaped in strings
 797                         // Clean up the escape sequence to avoid parsing errors by clients
 798                         return '\\' . dechex( ord( $char ) ) . ' ';
 799                 } else {
 800                         // Decode unnecessary escape
 801                         return $char;
 802                 }
 803         }
 804
 805         /**
 806          * Take a tag soup fragment listing an HTML element's attributes
 807          * and normalize it to well-formed XML, discarding unwanted attributes.
 808          * Output is safe for further wikitext processing, with escaping of
 809          * values that could trigger problems.
 810          *
 811          * - Normalizes attribute names to lowercase
 812          * - Discards attributes not on a whitelist for the given element
 813          * - Turns broken or invalid entities into plaintext
 814          * - Double-quotes all attribute values
 815          * - Attributes without values are given the name as attribute
 816          * - Double attributes are discarded
 817          * - Unsafe style attributes are discarded
 818          * - Prepends space if there are attributes.
 819          *
 820          * @param $text String
 821          * @param $element String
 822          * @return String
 823          */
 824         static function fixTagAttributes( $text, $element ) {
 825                 if( trim( $text ) == '' ) {
 826                         return '';
 827                 }
 828
 829                 $stripped = Sanitizer::validateTagAttributes(
 830                         Sanitizer::decodeTagAttributes( $text ), $element );
 831
 832                 $attribs = array();
 833                 foreach( $stripped as $attribute => $value ) {
 834                         $encAttribute = htmlspecialchars( $attribute );
 835                         $encValue = Sanitizer::safeEncodeAttribute( $value );
 836
 837                         $attribs[] = "$encAttribute=\"$encValue\"";
 838                 }
 839                 return count( $attribs ) ? ' ' . implode( ' ', $attribs ) : '';
 840         }
 841
 842         /**
 843          * Encode an attribute value for HTML output.
 844          * @param $text String
 845          * @return HTML-encoded text fragment
 846          */
 847         static function encodeAttribute( $text ) {
 848                 $encValue = htmlspecialchars( $text, ENT_QUOTES );
 849
 850                 // Whitespace is normalized during attribute decoding,
 851                 // so if we've been passed non-spaces we must encode them
 852                 // ahead of time or they won't be preserved.
 853                 $encValue = strtr( $encValue, array(
 854                         "\n" => '&#10;',
 855                         "\r" => '&#13;',
 856                         "\t" => '&#9;',
 857                 ) );
 858
 859                 return $encValue;
 860         }
 861
 862         /**
 863          * Encode an attribute value for HTML tags, with extra armoring
 864          * against further wiki processing.
 865          * @param $text String
 866          * @return HTML-encoded text fragment
 867          */
 868         static function safeEncodeAttribute( $text ) {
 869                 $encValue = Sanitizer::encodeAttribute( $text );
 870
 871                 # Templates and links may be expanded in later parsing,
 872                 # creating invalid or dangerous output. Suppress this.
 873                 $encValue = strtr( $encValue, array(
 874                         '<'    => '&lt;',   // This should never happen,
 875                         '>'    => '&gt;',   // we've received invalid input
 876                         '"'    => '&quot;', // which should have been escaped.
 877                         '{'    => '&#123;',
 878                         '['    => '&#91;',
 879                         "''"   => '&#39;&#39;',
 880                         'ISBN' => '&#73;SBN',
 881                         'RFC'  => '&#82;FC',
 882                         'PMID' => '&#80;MID',
 883                         '|'    => '&#124;',
 884                         '__'   => '&#95;_',
 885                 ) );
 886
 887                 # Stupid hack
 888                 $encValue = preg_replace_callback(
 889                         '/(' . wfUrlProtocols() . ')/',
 890                         array( 'Sanitizer', 'armorLinksCallback' ),
 891                         $encValue );
 892                 return $encValue;
 893         }
 894
 895         /**
 896          * Given a value, escape it so that it can be used in an id attribute and
 897          * return it.  This will use HTML5 validation if $wgExperimentalHtmlIds is
 898          * true, allowing anything but ASCII whitespace.  Otherwise it will use
 899          * HTML 4 rules, which means a narrow subset of ASCII, with bad characters
 900          * escaped with lots of dots.
 901          *
 902          * To ensure we don't have to bother escaping anything, we also strip ', ",
 903          * & even if $wgExperimentalIds is true.  TODO: Is this the best tactic?
 904          * We also strip # because it upsets IE, and % because it could be
 905          * ambiguous if it's part of something that looks like a percent escape
 906          * (which don't work reliably in fragments cross-browser).
 907          *
 908          * @see http://www.w3.org/TR/html401/types.html#type-name Valid characters
 909          *                                                          in the id and
 910          *                                                          name attributes
 911          * @see http://www.w3.org/TR/html401/struct/links.html#h-12.2.3 Anchors with the id attribute
 912          * @see http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-id-attribute
 913          *   HTML5 definition of id attribute
 914          *
 915          * @param $id String: id to escape
 916          * @param $options Mixed: string or array of strings (default is array()):
 917          *   'noninitial': This is a non-initial fragment of an id, not a full id,
 918          *       so don't pay attention if the first character isn't valid at the
 919          *       beginning of an id.  Only matters if $wgExperimentalHtmlIds is
 920          *       false.
 921          *   'legacy': Behave the way the old HTML 4-based ID escaping worked even
 922          *       if $wgExperimentalHtmlIds is used, so we can generate extra
 923          *       anchors and links won't break.
 924          * @return String
 925          */
 926         static function escapeId( $id, $options = array() ) {
 927                 global $wgHtml5, $wgExperimentalHtmlIds;
 928                 $options = (array)$options;
 929
 930                 if ( $wgHtml5 && $wgExperimentalHtmlIds && !in_array( 'legacy', $options ) ) {
 931                         $id = Sanitizer::decodeCharReferences( $id );
 932                         $id = preg_replace( '/[ \t\n\r\f_\'"&#%]+/', '_', $id );
 933                         $id = trim( $id, '_' );
 934                         if ( $id === '' ) {
 935                                 # Must have been all whitespace to start with.
 936                                 return '_';
 937                         } else {
 938                                 return $id;
 939                         }
 940                 }
 941
 942                 # HTML4-style escaping
 943                 static $replace = array(
 944                         '%3A' => ':',
 945                         '%' => '.'
 946                 );
 947
 948                 $id = urlencode( Sanitizer::decodeCharReferences( strtr( $id, ' ', '_' ) ) );
 949                 $id = str_replace( array_keys( $replace ), array_values( $replace ), $id );
 950
 951                 if ( !preg_match( '/^[a-zA-Z]/', $id )
 952                 && !in_array( 'noninitial', $options ) )  {
 953                         // Initial character must be a letter!
 954                         $id = "x$id";
 955                 }
 956                 return $id;
 957         }
 958
 959         /**
 960          * Given a value, escape it so that it can be used as a CSS class and
 961          * return it.
 962          *
 963          * @todo For extra validity, input should be validated UTF-8.
 964          *
 965          * @see http://www.w3.org/TR/CSS21/syndata.html Valid characters/format
 966          *
 967          * @param $class String
 968          * @return String
 969          */
 970         static function escapeClass( $class ) {
 971                 // Convert ugly stuff to underscores and kill underscores in ugly places
 972                 return rtrim(preg_replace(
 973                         array('/(^[0-9\\-])|[\\x00-\\x20!"#$%&\'()*+,.\\/:;<=>?@[\\]^`{|}~]|\\xC2\\xA0/','/_+/'),
 974                         '_',
 975                         $class ), '_');
 976         }
 977
 978         /**
 979          * Given HTML input, escape with htmlspecialchars but un-escape entites.
 980          * This allows (generally harmless) entities like &#160; to survive.
 981          *
 982          * @param $html String to escape
 983          * @return String: escaped input
 984          */
 985         static function escapeHtmlAllowEntities( $html ) {
 986                 $html = Sanitizer::decodeCharReferences( $html );
 987                 # It seems wise to escape ' as well as ", as a matter of course.  Can't
 988                 # hurt.
 989                 $html = htmlspecialchars( $html, ENT_QUOTES );
 990                 return $html;
 991         }
 992
 993         /**
 994          * Regex replace callback for armoring links against further processing.
 995          * @param $matches Array
 996          * @return string
 997          */
 998         private static function armorLinksCallback( $matches ) {
 999                 return str_replace( ':', '&#58;', $matches[1] );
1000         }
1001
1002         /**
1003          * Return an associative array of attribute names and values from
1004          * a partial tag string. Attribute names are forces to lowercase,
1005          * character references are decoded to UTF-8 text.
1006          *
1007          * @param $text String
1008          * @return Array
1009          */
1010         public static function decodeTagAttributes( $text ) {
1011                 if( trim( $text ) == '' ) {
1012                         return array();
1013                 }
1014
1015                 $attribs = array();
1016                 $pairs = array();
1017                 if( !preg_match_all(
1018                         MW_ATTRIBS_REGEX,
1019                         $text,
1020                         $pairs,
1021                         PREG_SET_ORDER ) ) {
1022                         return $attribs;
1023                 }
1024
1025                 foreach( $pairs as $set ) {
1026                         $attribute = strtolower( $set[1] );
1027                         $value = Sanitizer::getTagAttributeCallback( $set );
1028
1029                         // Normalize whitespace
1030                         $value = preg_replace( '/[\t\r\n ]+/', ' ', $value );
1031                         $value = trim( $value );
1032
1033                         // Decode character references
1034                         $attribs[$attribute] = Sanitizer::decodeCharReferences( $value );
1035                 }
1036                 return $attribs;
1037         }
1038
1039         /**
1040          * Pick the appropriate attribute value from a match set from the
1041          * MW_ATTRIBS_REGEX matches.
1042          *
1043          * @param $set Array
1044          * @return String
1045          */
1046         private static function getTagAttributeCallback( $set ) {
1047                 if( isset( $set[6] ) ) {
1048                         # Illegal #XXXXXX color with no quotes.
1049                         return $set[6];
1050                 } elseif( isset( $set[5] ) ) {
1051                         # No quotes.
1052                         return $set[5];
1053                 } elseif( isset( $set[4] ) ) {
1054                         # Single-quoted
1055                         return $set[4];
1056                 } elseif( isset( $set[3] ) ) {
1057                         # Double-quoted
1058                         return $set[3];
1059                 } elseif( !isset( $set[2] ) ) {
1060                         # In XHTML, attributes must have a value.
1061                         # For 'reduced' form, return explicitly the attribute name here.
1062                         return $set[1];
1063                 } else {
1064                         throw new MWException( "Tag conditions not met. This should never happen and is a bug." );
1065                 }
1066         }
1067
1068         /**
1069          * Normalize whitespace and character references in an XML source-
1070          * encoded text for an attribute value.
1071          *
1072          * See http://www.w3.org/TR/REC-xml/#AVNormalize for background,
1073          * but note that we're not returning the value, but are returning
1074          * XML source fragments that will be slapped into output.
1075          *
1076          * @param $text String
1077          * @return String
1078          */
1079         private static function normalizeAttributeValue( $text ) {
1080                 return str_replace( '"', '&quot;',
1081                         self::normalizeWhitespace(
1082                                 Sanitizer::normalizeCharReferences( $text ) ) );
1083         }
1084
1085         private static function normalizeWhitespace( $text ) {
1086                 return preg_replace(
1087                         '/\r\n|[\x20\x0d\x0a\x09]/',
1088                         ' ',
1089                         $text );
1090         }
1091
1092         /**
1093          * Normalizes whitespace in a section name, such as might be returned
1094          * by Parser::stripSectionName(), for use in the id's that are used for
1095          * section links.
1096          *
1097          * @param $section String
1098          * @return String
1099          */
1100         static function normalizeSectionNameWhitespace( $section ) {
1101                 return trim( preg_replace( '/[ _]+/', ' ', $section ) );
1102         }
1103
1104         /**
1105          * Ensure that any entities and character references are legal
1106          * for XML and XHTML specifically. Any stray bits will be
1107          * &amp;-escaped to result in a valid text fragment.
1108          *
1109          * a. any named char refs must be known in XHTML
1110          * b. any numeric char refs must be legal chars, not invalid or forbidden
1111          * c. use &#x, not &#X
1112          * d. fix or reject non-valid attributes
1113          *
1114          * @param $text String
1115          * @return String
1116          * @private
1117          */
1118         static function normalizeCharReferences( $text ) {
1119                 return preg_replace_callback(
1120                         MW_CHAR_REFS_REGEX,
1121                         array( 'Sanitizer', 'normalizeCharReferencesCallback' ),
1122                         $text );
1123         }
1124         /**
1125          * @param $matches String
1126          * @return String
1127          */
1128         static function normalizeCharReferencesCallback( $matches ) {
1129                 $ret = null;
1130                 if( $matches[1] != '' ) {
1131                         $ret = Sanitizer::normalizeEntity( $matches[1] );
1132                 } elseif( $matches[2] != '' ) {
1133                         $ret = Sanitizer::decCharReference( $matches[2] );
1134                 } elseif( $matches[3] != ''  ) {
1135                         $ret = Sanitizer::hexCharReference( $matches[3] );
1136                 }
1137                 if( is_null( $ret ) ) {
1138                         return htmlspecialchars( $matches[0] );
1139                 } else {
1140                         return $ret;
1141                 }
1142         }
1143
1144         /**
1145          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1146          * return the named entity reference as is. If the entity is a
1147          * MediaWiki-specific alias, returns the HTML equivalent. Otherwise,
1148          * returns HTML-escaped text of pseudo-entity source (eg &amp;foo;)
1149          *
1150          * @param $name String
1151          * @return String
1152          */
1153         static function normalizeEntity( $name ) {
1154                 global $wgHtmlEntities, $wgHtmlEntityAliases;
1155                 if ( isset( $wgHtmlEntityAliases[$name] ) ) {
1156                         return "&{$wgHtmlEntityAliases[$name]};";
1157                 } elseif( isset( $wgHtmlEntities[$name] ) ) {
1158                         return "&$name;";
1159                 } else {
1160                         return "&amp;$name;";
1161                 }
1162         }
1163
1164         static function decCharReference( $codepoint ) {
1165                 $point = intval( $codepoint );
1166                 if( Sanitizer::validateCodepoint( $point ) ) {
1167                         return sprintf( '&#%d;', $point );
1168                 } else {
1169                         return null;
1170                 }
1171         }
1172
1173         static function hexCharReference( $codepoint ) {
1174                 $point = hexdec( $codepoint );
1175                 if( Sanitizer::validateCodepoint( $point ) ) {
1176                         return sprintf( '&#x%x;', $point );
1177                 } else {
1178                         return null;
1179                 }
1180         }
1181
1182         /**
1183          * Returns true if a given Unicode codepoint is a valid character in XML.
1184          * @param $codepoint Integer
1185          * @return Boolean
1186          */
1187         private static function validateCodepoint( $codepoint ) {
1188                 return ($codepoint ==    0x09)
1189                         || ($codepoint ==    0x0a)
1190                         || ($codepoint ==    0x0d)
1191                         || ($codepoint >=    0x20 && $codepoint <=   0xd7ff)
1192                         || ($codepoint >=  0xe000 && $codepoint <=   0xfffd)
1193                         || ($codepoint >= 0x10000 && $codepoint <= 0x10ffff);
1194         }
1195
1196         /**
1197          * Decode any character references, numeric or named entities,
1198          * in the text and return a UTF-8 string.
1199          *
1200          * @param $text String
1201          * @return String
1202          */
1203         public static function decodeCharReferences( $text ) {
1204                 return preg_replace_callback(
1205                         MW_CHAR_REFS_REGEX,
1206                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1207                         $text );
1208         }
1209
1210         /**
1211          * Decode any character references, numeric or named entities,
1212          * in the next and normalize the resulting string. (bug 14952)
1213          *
1214          * This is useful for page titles, not for text to be displayed,
1215          * MediaWiki allows HTML entities to escape normalization as a feature.
1216          *
1217          * @param $text String (already normalized, containing entities)
1218          * @return String (still normalized, without entities)
1219          */
1220         public static function decodeCharReferencesAndNormalize( $text ) {
1221                 global $wgContLang;
1222                 $text = preg_replace_callback(
1223                         MW_CHAR_REFS_REGEX,
1224                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1225                         $text, /* limit */ -1, $count );
1226
1227                 if ( $count ) {
1228                         return $wgContLang->normalize( $text );
1229                 } else {
1230                         return $text;
1231                 }
1232         }
1233
1234         /**
1235          * @param $matches String
1236          * @return String
1237          */
1238         static function decodeCharReferencesCallback( $matches ) {
1239                 if( $matches[1] != '' ) {
1240                         return Sanitizer::decodeEntity( $matches[1] );
1241                 } elseif( $matches[2] != '' ) {
1242                         return  Sanitizer::decodeChar( intval( $matches[2] ) );
1243                 } elseif( $matches[3] != ''  ) {
1244                         return  Sanitizer::decodeChar( hexdec( $matches[3] ) );
1245                 }
1246                 # Last case should be an ampersand by itself
1247                 return $matches[0];
1248         }
1249
1250         /**
1251          * Return UTF-8 string for a codepoint if that is a valid
1252          * character reference, otherwise U+FFFD REPLACEMENT CHARACTER.
1253          * @param $codepoint Integer
1254          * @return String
1255          * @private
1256          */
1257         static function decodeChar( $codepoint ) {
1258                 if( Sanitizer::validateCodepoint( $codepoint ) ) {
1259                         return codepointToUtf8( $codepoint );
1260                 } else {
1261                         return UTF8_REPLACEMENT;
1262                 }
1263         }
1264
1265         /**
1266          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1267          * return the UTF-8 encoding of that character. Otherwise, returns
1268          * pseudo-entity source (eg &foo;)
1269          *
1270          * @param $name Strings
1271          * @return String
1272          */
1273         static function decodeEntity( $name ) {
1274                 global $wgHtmlEntities, $wgHtmlEntityAliases;
1275                 if ( isset( $wgHtmlEntityAliases[$name] ) ) {
1276                         $name = $wgHtmlEntityAliases[$name];
1277                 }
1278                 if( isset( $wgHtmlEntities[$name] ) ) {
1279                         return codepointToUtf8( $wgHtmlEntities[$name] );
1280                 } else {
1281                         return "&$name;";
1282                 }
1283         }
1284
1285         /**
1286          * Fetch the whitelist of acceptable attributes for a given element name.
1287          *
1288          * @param $element String
1289          * @return Array
1290          */
1291         static function attributeWhitelist( $element ) {
1292                 static $list;
1293                 if( !isset( $list ) ) {
1294                         $list = Sanitizer::setupAttributeWhitelist();
1295                 }
1296                 return isset( $list[$element] )
1297                         ? $list[$element]
1298                         : array();
1299         }
1300
1301         /**
1302          * Foreach array key (an allowed HTML element), return an array
1303          * of allowed attributes
1304          * @return Array
1305          */
1306         static function setupAttributeWhitelist() {
1307                 global $wgAllowRdfaAttributes, $wgHtml5, $wgAllowMicrodataAttributes;
1308
1309                 $common = array( 'id', 'class', 'lang', 'dir', 'title', 'style' );
1310
1311                 if ( $wgAllowRdfaAttributes ) {
1312                         #RDFa attributes as specified in section 9 of http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014
1313                         $common = array_merge( $common, array(
1314                             'about', 'property', 'resource', 'datatype', 'typeof',
1315                         ) );
1316                 }
1317
1318                 if ( $wgHtml5 && $wgAllowMicrodataAttributes ) {
1319                         # add HTML5 microdata tages as pecified by http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#the-microdata-model
1320                         $common = array_merge( $common, array(
1321                             'itemid', 'itemprop', 'itemref', 'itemscope', 'itemtype'
1322                         ) );
1323                 }
1324
1325                 $block = array_merge( $common, array( 'align' ) );
1326                 $tablealign = array( 'align', 'char', 'charoff', 'valign' );
1327                 $tablecell = array( 'abbr',
1328                                     'axis',
1329                                     'headers',
1330                                     'scope',
1331                                     'rowspan',
1332                                     'colspan',
1333                                     'nowrap', # deprecated
1334                                     'width',  # deprecated
1335                                     'height', # deprecated
1336                                     'bgcolor' # deprecated
1337                                     );
1338
1339                 # Numbers refer to sections in HTML 4.01 standard describing the element.
1340                 # See: http://www.w3.org/TR/html4/
1341                 $whitelist = array (
1342                         # 7.5.4
1343                         'div'        => $block,
1344                         'center'     => $common, # deprecated
1345                         'span'       => $block, # ??
1346
1347                         # 7.5.5
1348                         'h1'         => $block,
1349                         'h2'         => $block,
1350                         'h3'         => $block,
1351                         'h4'         => $block,
1352                         'h5'         => $block,
1353                         'h6'         => $block,
1354
1355                         # 7.5.6
1356                         # address
1357
1358                         # 8.2.4
1359                         # bdo
1360
1361                         # 9.2.1
1362                         'em'         => $common,
1363                         'strong'     => $common,
1364                         'cite'       => $common,
1365                         'dfn'        => $common,
1366                         'code'       => $common,
1367                         'samp'       => $common,
1368                         'kbd'        => $common,
1369                         'var'        => $common,
1370                         'abbr'       => $common,
1371                         # acronym
1372
1373                         # 9.2.2
1374                         'blockquote' => array_merge( $common, array( 'cite' ) ),
1375                         # q
1376
1377                         # 9.2.3
1378                         'sub'        => $common,
1379                         'sup'        => $common,
1380
1381                         # 9.3.1
1382                         'p'          => $block,
1383
1384                         # 9.3.2
1385                         'br'         => array( 'id', 'class', 'title', 'style', 'clear' ),
1386
1387                         # 9.3.4
1388                         'pre'        => array_merge( $common, array( 'width' ) ),
1389
1390                         # 9.4
1391                         'ins'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1392                         'del'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1393
1394                         # 10.2
1395                         'ul'         => array_merge( $common, array( 'type' ) ),
1396                         'ol'         => array_merge( $common, array( 'type', 'start' ) ),
1397                         'li'         => array_merge( $common, array( 'type', 'value' ) ),
1398
1399                         # 10.3
1400                         'dl'         => $common,
1401                         'dd'         => $common,
1402                         'dt'         => $common,
1403
1404                         # 11.2.1
1405                         'table'      => array_merge( $common,
1406                                                                 array( 'summary', 'width', 'border', 'frame',
1407                                                                                 'rules', 'cellspacing', 'cellpadding',
1408                                                                                 'align', 'bgcolor',
1409                                                                 ) ),
1410
1411                         # 11.2.2
1412                         'caption'    => array_merge( $common, array( 'align' ) ),
1413
1414                         # 11.2.3
1415                         'thead'      => array_merge( $common, $tablealign ),
1416                         'tfoot'      => array_merge( $common, $tablealign ),
1417                         'tbody'      => array_merge( $common, $tablealign ),
1418
1419                         # 11.2.4
1420                         'colgroup'   => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1421                         'col'        => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1422
1423                         # 11.2.5
1424                         'tr'         => array_merge( $common, array( 'bgcolor' ), $tablealign ),
1425
1426                         # 11.2.6
1427                         'td'         => array_merge( $common, $tablecell, $tablealign ),
1428                         'th'         => array_merge( $common, $tablecell, $tablealign ),
1429
1430                         # 12.2 # NOTE: <a> is not allowed directly, but the attrib whitelist is used from the Parser object
1431                         'a'          => array_merge( $common, array( 'href', 'rel', 'rev' ) ), # rel/rev esp. for RDFa
1432
1433                         # 13.2
1434                         # Not usually allowed, but may be used for extension-style hooks
1435                         # such as <math> when it is rasterized, or if $wgAllowImageTag is
1436                         # true
1437                         'img'        => array_merge( $common, array( 'alt', 'src', 'width', 'height' ) ),
1438
1439                         # 15.2.1
1440                         'tt'         => $common,
1441                         'b'          => $common,
1442                         'i'          => $common,
1443                         'big'        => $common,
1444                         'small'      => $common,
1445                         'strike'     => $common,
1446                         's'          => $common,
1447                         'u'          => $common,
1448
1449                         # 15.2.2
1450                         'font'       => array_merge( $common, array( 'size', 'color', 'face' ) ),
1451                         # basefont
1452
1453                         # 15.3
1454                         'hr'         => array_merge( $common, array( 'noshade', 'size', 'width' ) ),
1455
1456                         # XHTML Ruby annotation text module, simple ruby only.
1457                         # http://www.w3c.org/TR/ruby/
1458                         'ruby'       => $common,
1459                         # rbc
1460                         # rtc
1461                         'rb'         => $common,
1462                         'rt'         => $common, #array_merge( $common, array( 'rbspan' ) ),
1463                         'rp'         => $common,
1464
1465                         # MathML root element, where used for extensions
1466                         # 'title' may not be 100% valid here; it's XHTML
1467                         # http://www.w3.org/TR/REC-MathML/
1468                         'math'       => array( 'class', 'style', 'id', 'title' ),
1469                         );
1470                 return $whitelist;
1471         }
1472
1473         /**
1474          * Take a fragment of (potentially invalid) HTML and return
1475          * a version with any tags removed, encoded as plain text.
1476          *
1477          * Warning: this return value must be further escaped for literal
1478          * inclusion in HTML output as of 1.10!
1479          *
1480          * @param $text String: HTML fragment
1481          * @return String
1482          */
1483         static function stripAllTags( $text ) {
1484                 # Actual <tags>
1485                 $text = StringUtils::delimiterReplace( '<', '>', '', $text );
1486
1487                 # Normalize &entities and whitespace
1488                 $text = self::decodeCharReferences( $text );
1489                 $text = self::normalizeWhitespace( $text );
1490
1491                 return $text;
1492         }
1493
1494         /**
1495          * Hack up a private DOCTYPE with HTML's standard entity declarations.
1496          * PHP 4 seemed to know these if you gave it an HTML doctype, but
1497          * PHP 5.1 doesn't.
1498          *
1499          * Use for passing XHTML fragments to PHP's XML parsing functions
1500          *
1501          * @return String
1502          */
1503         static function hackDocType() {
1504                 global $wgHtmlEntities;
1505                 $out = "<!DOCTYPE html [\n";
1506                 foreach( $wgHtmlEntities as $entity => $codepoint ) {
1507                         $out .= "<!ENTITY $entity \"&#$codepoint;\">";
1508                 }
1509                 $out .= "]>\n";
1510                 return $out;
1511         }
1512
1513         static function cleanUrl( $url ) {
1514                 # Normalize any HTML entities in input. They will be
1515                 # re-escaped by makeExternalLink().
1516                 $url = Sanitizer::decodeCharReferences( $url );
1517
1518                 # Escape any control characters introduced by the above step
1519                 $url = preg_replace( '/[\][<>"\\x00-\\x20\\x7F\|]/e', "urlencode('\\0')", $url );
1520
1521                 # Validate hostname portion
1522                 $matches = array();
1523                 if( preg_match( '!^([^:]+:)(//[^/]+)?(.*)$!iD', $url, $matches ) ) {
1524                         list( /* $whole */, $protocol, $host, $rest ) = $matches;
1525
1526                         // Characters that will be ignored in IDNs.
1527                         // http://tools.ietf.org/html/3454#section-3.1
1528                         // Strip them before further processing so blacklists and such work.
1529                         $strip = "/
1530                                 \\s|          # general whitespace
1531                                 \xc2\xad|     # 00ad SOFT HYPHEN
1532                                 \xe1\xa0\x86| # 1806 MONGOLIAN TODO SOFT HYPHEN
1533                                 \xe2\x80\x8b| # 200b ZERO WIDTH SPACE
1534                                 \xe2\x81\xa0| # 2060 WORD JOINER
1535                                 \xef\xbb\xbf| # feff ZERO WIDTH NO-BREAK SPACE
1536                                 \xcd\x8f|     # 034f COMBINING GRAPHEME JOINER
1537                                 \xe1\xa0\x8b| # 180b MONGOLIAN FREE VARIATION SELECTOR ONE
1538                                 \xe1\xa0\x8c| # 180c MONGOLIAN FREE VARIATION SELECTOR TWO
1539                                 \xe1\xa0\x8d| # 180d MONGOLIAN FREE VARIATION SELECTOR THREE
1540                                 \xe2\x80\x8c| # 200c ZERO WIDTH NON-JOINER
1541                                 \xe2\x80\x8d| # 200d ZERO WIDTH JOINER
1542                                 [\xef\xb8\x80-\xef\xb8\x8f] # fe00-fe00f VARIATION SELECTOR-1-16
1543                                 /xuD";
1544
1545                         $host = preg_replace( $strip, '', $host );
1546
1547                         // @todo Fixme: validate hostnames here
1548
1549                         return $protocol . $host . $rest;
1550                 } else {
1551                         return $url;
1552                 }
1553         }
1554
1555 }