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          |&\#x([0-9A-Za-z]+);
  35          |&\#X([0-9A-Za-z]+);
  36          |(&)/x' );
  37
  38 /**
  39  * Regular expression to match HTML/XML attribute pairs within a tag.
  40  * Allows some... latitude.
  41  * Used in Sanitizer::fixTagAttributes and Sanitizer::decodeTagAttributes
  42  */
  43 $attrib_first = '[:A-Z_a-z]';
  44 $attrib = '[:A-Z_a-z-.0-9]';
  45 $space = '[\x09\x0a\x0d\x20]';
  46 define( 'MW_ATTRIBS_REGEX',
  47         "/(?:^|$space)({$attrib_first}{$attrib}*)
  48           ($space*=$space*
  49                 (?:
  50                  # The attribute value: quoted or alone
  51                   \"([^<\"]*)\"
  52                  | '([^<']*)'
  53                  |  ([a-zA-Z0-9!#$%&()*,\\-.\\/:;<>?@[\\]^_`{|}~]+)
  54                  |  (\#[0-9a-fA-F]+) # Technically wrong, but lots of
  55                                                          # colors are specified like this.
  56                                                          # We'll be normalizing it.
  57                 )
  58            )?(?=$space|\$)/sx" );
  59
  60 /**
  61  * Regular expression to match URIs that could trigger script execution
  62  */
  63 define( 'MW_EVIL_URI_PATTERN', '!(^|\s|\*/\s*)(javascript|vbscript)([^\w]|$)!i' );
  64
  65 /**
  66  * Regular expression to match namespace attributes
  67  */
  68 define( 'MW_XMLNS_ATTRIBUTE_PATTRN', "/^xmlns:$attrib+$/" );
  69
  70 /**
  71  * List of all named character entities defined in HTML 4.01
  72  * http://www.w3.org/TR/html4/sgml/entities.html
  73  * @private
  74  */
  75 global $wgHtmlEntities;
  76 $wgHtmlEntities = array(
  77         'Aacute'   => 193,
  78         'aacute'   => 225,
  79         'Acirc'    => 194,
  80         'acirc'    => 226,
  81         'acute'    => 180,
  82         'AElig'    => 198,
  83         'aelig'    => 230,
  84         'Agrave'   => 192,
  85         'agrave'   => 224,
  86         'alefsym'  => 8501,
  87         'Alpha'    => 913,
  88         'alpha'    => 945,
  89         'amp'      => 38,
  90         'and'      => 8743,
  91         'ang'      => 8736,
  92         'Aring'    => 197,
  93         'aring'    => 229,
  94         'asymp'    => 8776,
  95         'Atilde'   => 195,
  96         'atilde'   => 227,
  97         'Auml'     => 196,
  98         'auml'     => 228,
  99         'bdquo'    => 8222,
 100         'Beta'     => 914,
 101         'beta'     => 946,
 102         'brvbar'   => 166,
 103         'bull'     => 8226,
 104         'cap'      => 8745,
 105         'Ccedil'   => 199,
 106         'ccedil'   => 231,
 107         'cedil'    => 184,
 108         'cent'     => 162,
 109         'Chi'      => 935,
 110         'chi'      => 967,
 111         'circ'     => 710,
 112         'clubs'    => 9827,
 113         'cong'     => 8773,
 114         'copy'     => 169,
 115         'crarr'    => 8629,
 116         'cup'      => 8746,
 117         'curren'   => 164,
 118         'dagger'   => 8224,
 119         'Dagger'   => 8225,
 120         'darr'     => 8595,
 121         'dArr'     => 8659,
 122         'deg'      => 176,
 123         'Delta'    => 916,
 124         'delta'    => 948,
 125         'diams'    => 9830,
 126         'divide'   => 247,
 127         'Eacute'   => 201,
 128         'eacute'   => 233,
 129         'Ecirc'    => 202,
 130         'ecirc'    => 234,
 131         'Egrave'   => 200,
 132         'egrave'   => 232,
 133         'empty'    => 8709,
 134         'emsp'     => 8195,
 135         'ensp'     => 8194,
 136         'Epsilon'  => 917,
 137         'epsilon'  => 949,
 138         'equiv'    => 8801,
 139         'Eta'      => 919,
 140         'eta'      => 951,
 141         'ETH'      => 208,
 142         'eth'      => 240,
 143         'Euml'     => 203,
 144         'euml'     => 235,
 145         'euro'     => 8364,
 146         'exist'    => 8707,
 147         'fnof'     => 402,
 148         'forall'   => 8704,
 149         'frac12'   => 189,
 150         'frac14'   => 188,
 151         'frac34'   => 190,
 152         'frasl'    => 8260,
 153         'Gamma'    => 915,
 154         'gamma'    => 947,
 155         'ge'       => 8805,
 156         'gt'       => 62,
 157         'harr'     => 8596,
 158         'hArr'     => 8660,
 159         'hearts'   => 9829,
 160         'hellip'   => 8230,
 161         'Iacute'   => 205,
 162         'iacute'   => 237,
 163         'Icirc'    => 206,
 164         'icirc'    => 238,
 165         'iexcl'    => 161,
 166         'Igrave'   => 204,
 167         'igrave'   => 236,
 168         'image'    => 8465,
 169         'infin'    => 8734,
 170         'int'      => 8747,
 171         'Iota'     => 921,
 172         'iota'     => 953,
 173         'iquest'   => 191,
 174         'isin'     => 8712,
 175         'Iuml'     => 207,
 176         'iuml'     => 239,
 177         'Kappa'    => 922,
 178         'kappa'    => 954,
 179         'Lambda'   => 923,
 180         'lambda'   => 955,
 181         'lang'     => 9001,
 182         'laquo'    => 171,
 183         'larr'     => 8592,
 184         'lArr'     => 8656,
 185         'lceil'    => 8968,
 186         'ldquo'    => 8220,
 187         'le'       => 8804,
 188         'lfloor'   => 8970,
 189         'lowast'   => 8727,
 190         'loz'      => 9674,
 191         'lrm'      => 8206,
 192         'lsaquo'   => 8249,
 193         'lsquo'    => 8216,
 194         'lt'       => 60,
 195         'macr'     => 175,
 196         'mdash'    => 8212,
 197         'micro'    => 181,
 198         'middot'   => 183,
 199         'minus'    => 8722,
 200         'Mu'       => 924,
 201         'mu'       => 956,
 202         'nabla'    => 8711,
 203         'nbsp'     => 160,
 204         'ndash'    => 8211,
 205         'ne'       => 8800,
 206         'ni'       => 8715,
 207         'not'      => 172,
 208         'notin'    => 8713,
 209         'nsub'     => 8836,
 210         'Ntilde'   => 209,
 211         'ntilde'   => 241,
 212         'Nu'       => 925,
 213         'nu'       => 957,
 214         'Oacute'   => 211,
 215         'oacute'   => 243,
 216         'Ocirc'    => 212,
 217         'ocirc'    => 244,
 218         'OElig'    => 338,
 219         'oelig'    => 339,
 220         'Ograve'   => 210,
 221         'ograve'   => 242,
 222         'oline'    => 8254,
 223         'Omega'    => 937,
 224         'omega'    => 969,
 225         'Omicron'  => 927,
 226         'omicron'  => 959,
 227         'oplus'    => 8853,
 228         'or'       => 8744,
 229         'ordf'     => 170,
 230         'ordm'     => 186,
 231         'Oslash'   => 216,
 232         'oslash'   => 248,
 233         'Otilde'   => 213,
 234         'otilde'   => 245,
 235         'otimes'   => 8855,
 236         'Ouml'     => 214,
 237         'ouml'     => 246,
 238         'para'     => 182,
 239         'part'     => 8706,
 240         'permil'   => 8240,
 241         'perp'     => 8869,
 242         'Phi'      => 934,
 243         'phi'      => 966,
 244         'Pi'       => 928,
 245         'pi'       => 960,
 246         'piv'      => 982,
 247         'plusmn'   => 177,
 248         'pound'    => 163,
 249         'prime'    => 8242,
 250         'Prime'    => 8243,
 251         'prod'     => 8719,
 252         'prop'     => 8733,
 253         'Psi'      => 936,
 254         'psi'      => 968,
 255         'quot'     => 34,
 256         'radic'    => 8730,
 257         'rang'     => 9002,
 258         'raquo'    => 187,
 259         'rarr'     => 8594,
 260         'rArr'     => 8658,
 261         'rceil'    => 8969,
 262         'rdquo'    => 8221,
 263         'real'     => 8476,
 264         'reg'      => 174,
 265         'rfloor'   => 8971,
 266         'Rho'      => 929,
 267         'rho'      => 961,
 268         'rlm'      => 8207,
 269         'rsaquo'   => 8250,
 270         'rsquo'    => 8217,
 271         'sbquo'    => 8218,
 272         'Scaron'   => 352,
 273         'scaron'   => 353,
 274         'sdot'     => 8901,
 275         'sect'     => 167,
 276         'shy'      => 173,
 277         'Sigma'    => 931,
 278         'sigma'    => 963,
 279         'sigmaf'   => 962,
 280         'sim'      => 8764,
 281         'spades'   => 9824,
 282         'sub'      => 8834,
 283         'sube'     => 8838,
 284         'sum'      => 8721,
 285         'sup'      => 8835,
 286         'sup1'     => 185,
 287         'sup2'     => 178,
 288         'sup3'     => 179,
 289         'supe'     => 8839,
 290         'szlig'    => 223,
 291         'Tau'      => 932,
 292         'tau'      => 964,
 293         'there4'   => 8756,
 294         'Theta'    => 920,
 295         'theta'    => 952,
 296         'thetasym' => 977,
 297         'thinsp'   => 8201,
 298         'THORN'    => 222,
 299         'thorn'    => 254,
 300         'tilde'    => 732,
 301         'times'    => 215,
 302         'trade'    => 8482,
 303         'Uacute'   => 218,
 304         'uacute'   => 250,
 305         'uarr'     => 8593,
 306         'uArr'     => 8657,
 307         'Ucirc'    => 219,
 308         'ucirc'    => 251,
 309         'Ugrave'   => 217,
 310         'ugrave'   => 249,
 311         'uml'      => 168,
 312         'upsih'    => 978,
 313         'Upsilon'  => 933,
 314         'upsilon'  => 965,
 315         'Uuml'     => 220,
 316         'uuml'     => 252,
 317         'weierp'   => 8472,
 318         'Xi'       => 926,
 319         'xi'       => 958,
 320         'Yacute'   => 221,
 321         'yacute'   => 253,
 322         'yen'      => 165,
 323         'Yuml'     => 376,
 324         'yuml'     => 255,
 325         'Zeta'     => 918,
 326         'zeta'     => 950,
 327         'zwj'      => 8205,
 328         'zwnj'     => 8204 );
 329
 330 /**
 331  * Character entity aliases accepted by MediaWiki
 332  */
 333 global $wgHtmlEntityAliases;
 334 $wgHtmlEntityAliases = array(
 335         'רלמ' => 'rlm',
 336         'رلم' => 'rlm',
 337 );
 338
 339
 340 /**
 341  * XHTML sanitizer for MediaWiki
 342  * @ingroup Parser
 343  */
 344 class Sanitizer {
 345         /**
 346          * Cleans up HTML, removes dangerous tags and attributes, and
 347          * removes HTML comments
 348          * @private
 349          * @param $text String
 350          * @param $processCallback Callback to do any variable or parameter replacements in HTML attribute values
 351          * @param $args Array for the processing callback
 352          * @param $extratags Array for any extra tags to include
 353          * @param $removetags Array for any tags (default or extra) to exclude
 354          * @return string
 355          */
 356         static function removeHTMLtags( $text, $processCallback = null, $args = array(), $extratags = array(), $removetags = array() ) {
 357                 global $wgUseTidy;
 358
 359                 static $htmlpairsStatic, $htmlsingle, $htmlsingleonly, $htmlnest, $tabletags,
 360                         $htmllist, $listtags, $htmlsingleallowed, $htmlelementsStatic, $staticInitialised;
 361
 362                 wfProfileIn( __METHOD__ );
 363
 364                 if ( !$staticInitialised ) {
 365
 366                         $htmlpairsStatic = array( # Tags that must be closed
 367                                 'b', 'del', 'i', 'ins', 'u', 'font', 'big', 'small', 'sub', 'sup', 'h1',
 368                                 'h2', 'h3', 'h4', 'h5', 'h6', 'cite', 'code', 'em', 's',
 369                                 'strike', 'strong', 'tt', 'var', 'div', 'center',
 370                                 'blockquote', 'ol', 'ul', 'dl', 'table', 'caption', 'pre',
 371                                 'ruby', 'rt' , 'rb' , 'rp', 'p', 'span', 'u', 'abbr', 'dfn'
 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                 // Decode escape sequences and line continuation
 751                 // See the grammar in the CSS 2 spec, appendix D.
 752                 static $decodeRegex;
 753                 if ( !$decodeRegex ) {
 754                         $space = '[\\x20\\t\\r\\n\\f]';
 755                         $nl = '(?:\\n|\\r\\n|\\r|\\f)';
 756                         $backslash = '\\\\';
 757                         $decodeRegex = "/ $backslash
 758                                 (?:
 759                                         ($nl) |  # 1. Line continuation
 760                                         ([0-9A-Fa-f]{1,6})$space? |  # 2. character number
 761                                         (.) | # 3. backslash cancelling special meaning
 762                                         () | # 4. backslash at end of string
 763                                 )/xu";
 764                 }
 765                 $value = preg_replace_callback( $decodeRegex,
 766                         array( __CLASS__, 'cssDecodeCallback' ), $value );
 767
 768                 // Reject problematic keywords and control characters
 769                 if ( preg_match( '/[\000-\010\016-\037\177]/', $value ) ) {
 770                         return '/* invalid control char */';
 771                 } elseif ( preg_match( '! expression | filter\s*: | accelerator\s*: | url\s*\( !ix', $value ) ) {
 772                         return '/* insecure input */';
 773                 }
 774                 return $value;
 775         }
 776
 777         static function cssDecodeCallback( $matches ) {
 778                 if ( $matches[1] !== '' ) {
 779                         // Line continuation
 780                         return '';
 781                 } elseif ( $matches[2] !== '' ) {
 782                         $char = codepointToUtf8( hexdec( $matches[2] ) );
 783                 } elseif ( $matches[3] !== '' ) {
 784                         $char = $matches[3];
 785                 } else {
 786                         $char = '\\';
 787                 }
 788                 if ( $char == "\n" || $char == '"' || $char == "'" || $char == '\\' ) {
 789                         // These characters need to be escaped in strings
 790                         // Clean up the escape sequence to avoid parsing errors by clients
 791                         return '\\' . dechex( ord( $char ) ) . ' ';
 792                 } else {
 793                         // Decode unnecessary escape
 794                         return $char;
 795                 }
 796         }
 797
 798         /**
 799         * Take an associative array of attribute name/value pairs
 800         * and generate a css style representing all the style-related
 801         * attributes. If there already a style attribute in the array,
 802         * it is also included in the value returned.
 803         */
 804         static function styleFromAttributes( $attributes ) {
 805                 $styles = array();
 806
 807                 foreach ( $attributes as $attribute => $value ) {
 808                         if ( $attribute == 'bgcolor' ) {
 809                                 $styles[] = "background-color: $value";
 810                         } else if ( $attribute == 'border' ) {
 811                                 $styles[] = "border-width: $value";
 812                         } else if ( $attribute == 'align' ) {
 813                                 $styles[] = "text-align: $value";
 814                         } else if ( $attribute == 'valign' ) {
 815                                 $styles[] = "vertical-align: $value";
 816                         } else if ( $attribute == 'width' ) {
 817                                 if ( preg_match( '/\d+/', $value ) === false ) {
 818                                       $value .= 'px';
 819                                 }
 820
 821                                 $styles[] = "width: $value";
 822                         } else if ( $attribute == 'height' ) {
 823                                 if ( preg_match( '/\d+/', $value ) === false ) {
 824                                       $value .= 'px';
 825                                 }
 826
 827                                 $styles[] = "height: $value";
 828                         } else if ( $attribute == 'nowrap' ) {
 829                                 if ( $value ) {
 830                                         $styles[] = "white-space: nowrap";
 831                                 }
 832                         }
 833                 }
 834
 835                 if ( isset( $attributes[ 'style' ] ) ) {
 836                         $styles[] = $attributes[ 'style' ];
 837                 }
 838
 839                 if ( !$styles ) return '';
 840                 else return implode( '; ', $styles );
 841         }
 842
 843         /**
 844          * Take a tag soup fragment listing an HTML element's attributes
 845          * and normalize it to well-formed XML, discarding unwanted attributes.
 846          * Output is safe for further wikitext processing, with escaping of
 847          * values that could trigger problems.
 848          *
 849          * - Normalizes attribute names to lowercase
 850          * - Discards attributes not on a whitelist for the given element
 851          * - Turns broken or invalid entities into plaintext
 852          * - Double-quotes all attribute values
 853          * - Attributes without values are given the name as attribute
 854          * - Double attributes are discarded
 855          * - Unsafe style attributes are discarded
 856          * - Prepends space if there are attributes.
 857          *
 858          * @param $text String
 859          * @param $element String
 860          * @param $defaults Array (optional) associative array of default attributes to splice in.
 861          *                      class and style attributes are combined. Otherwise, values from
 862          *                      $attributes take precedence over values from $defaults.
 863          * @return String
 864          */
 865         static function fixTagAttributes( $text, $element, $defaults = null ) {
 866                 if( trim( $text ) == '' ) {
 867                         return '';
 868                 }
 869
 870                 $decoded = Sanitizer::decodeTagAttributes( $text );
 871                 $stripped = Sanitizer::validateTagAttributes( $decoded, $element );
 872                 $attribs = Sanitizer::collapseTagAttributes( $stripped, $defaults );
 873
 874                 return $attribs;
 875         }
 876
 877         /**
 878          * Take an associative array or attribute name/value pairs
 879          * and collapses it to well-formed XML.
 880          * Does not filter attributes.
 881          * Output is safe for further wikitext processing, with escaping of
 882          * values that could trigger problems.
 883          *
 884          * - Double-quotes all attribute values
 885          * - Prepends space if there are attributes.
 886          *
 887          * @param $attributes Array is an associative array of attribute name/value pairs.
 888          *                      Assumed to be sanitized already.
 889          * @param $defaults Array (optional) associative array of default attributes to splice in.
 890          *                      class and style attributes are combined. Otherwise, values from
 891          *                      $attributes take precedence over values from $defaults.
 892          * @return String
 893          */
 894         static function collapseTagAttributes( $attributes, $defaults = null ) {
 895                 if ( $defaults ) {
 896                         foreach( $defaults as $attribute => $value ) {
 897                                 if ( isset( $attributes[ $attribute ] ) ) {
 898                                         if ( $attribute == 'class' ) {
 899                                                 $value .= ' '. $attributes[ $attribute ];
 900                                         } else if ( $attribute == 'style' ) {
 901                                                 $value .= '; ' . $attributes[ $attribute ];
 902                                         } else {
 903                                                 continue;
 904                                         }
 905                                 }
 906
 907                                 $attributes[ $attribute ] = $value;
 908                         }
 909                 }
 910
 911                 $chunks = array();
 912
 913                 foreach( $attributes as $attribute => $value ) {
 914                         $encAttribute = htmlspecialchars( $attribute );
 915                         $encValue = Sanitizer::safeEncodeAttribute( $value );
 916
 917                         $chunks[] = "$encAttribute=\"$encValue\"";
 918                 }
 919                 return count( $chunks ) ? ' ' . implode( ' ', $chunks ) : '';
 920         }
 921
 922         /**
 923          * Encode an attribute value for HTML output.
 924          * @param $text String
 925          * @return HTML-encoded text fragment
 926          */
 927         static function encodeAttribute( $text ) {
 928                 $encValue = htmlspecialchars( $text, ENT_QUOTES );
 929
 930                 // Whitespace is normalized during attribute decoding,
 931                 // so if we've been passed non-spaces we must encode them
 932                 // ahead of time or they won't be preserved.
 933                 $encValue = strtr( $encValue, array(
 934                         "\n" => '&#10;',
 935                         "\r" => '&#13;',
 936                         "\t" => '&#9;',
 937                 ) );
 938
 939                 return $encValue;
 940         }
 941
 942         /**
 943          * Encode an attribute value for HTML tags, with extra armoring
 944          * against further wiki processing.
 945          * @param $text String
 946          * @return HTML-encoded text fragment
 947          */
 948         static function safeEncodeAttribute( $text ) {
 949                 $encValue = Sanitizer::encodeAttribute( $text );
 950
 951                 # Templates and links may be expanded in later parsing,
 952                 # creating invalid or dangerous output. Suppress this.
 953                 $encValue = strtr( $encValue, array(
 954                         '<'    => '&lt;',   // This should never happen,
 955                         '>'    => '&gt;',   // we've received invalid input
 956                         '"'    => '&quot;', // which should have been escaped.
 957                         '{'    => '&#123;',
 958                         '['    => '&#91;',
 959                         "''"   => '&#39;&#39;',
 960                         'ISBN' => '&#73;SBN',
 961                         'RFC'  => '&#82;FC',
 962                         'PMID' => '&#80;MID',
 963                         '|'    => '&#124;',
 964                         '__'   => '&#95;_',
 965                 ) );
 966
 967                 # Stupid hack
 968                 $encValue = preg_replace_callback(
 969                         '/(' . wfUrlProtocols() . ')/',
 970                         array( 'Sanitizer', 'armorLinksCallback' ),
 971                         $encValue );
 972                 return $encValue;
 973         }
 974
 975         /**
 976          * Given a value, escape it so that it can be used in an id attribute and
 977          * return it.  This will use HTML5 validation if $wgExperimentalHtmlIds is
 978          * true, allowing anything but ASCII whitespace.  Otherwise it will use
 979          * HTML 4 rules, which means a narrow subset of ASCII, with bad characters
 980          * escaped with lots of dots.
 981          *
 982          * To ensure we don't have to bother escaping anything, we also strip ', ",
 983          * & even if $wgExperimentalIds is true.  TODO: Is this the best tactic?
 984          * We also strip # because it upsets IE, and % because it could be
 985          * ambiguous if it's part of something that looks like a percent escape
 986          * (which don't work reliably in fragments cross-browser).
 987          *
 988          * @see http://www.w3.org/TR/html401/types.html#type-name Valid characters
 989          *                                                          in the id and
 990          *                                                          name attributes
 991          * @see http://www.w3.org/TR/html401/struct/links.html#h-12.2.3 Anchors with the id attribute
 992          * @see http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-id-attribute
 993          *   HTML5 definition of id attribute
 994          *
 995          * @param $id String: id to escape
 996          * @param $options Mixed: string or array of strings (default is array()):
 997          *   'noninitial': This is a non-initial fragment of an id, not a full id,
 998          *       so don't pay attention if the first character isn't valid at the
 999          *       beginning of an id.  Only matters if $wgExperimentalHtmlIds is
1000          *       false.
1001          *   'legacy': Behave the way the old HTML 4-based ID escaping worked even
1002          *       if $wgExperimentalHtmlIds is used, so we can generate extra
1003          *       anchors and links won't break.
1004          * @return String
1005          */
1006         static function escapeId( $id, $options = array() ) {
1007                 global $wgHtml5, $wgExperimentalHtmlIds;
1008                 $options = (array)$options;
1009
1010                 if ( $wgHtml5 && $wgExperimentalHtmlIds && !in_array( 'legacy', $options ) ) {
1011                         $id = Sanitizer::decodeCharReferences( $id );
1012                         $id = preg_replace( '/[ \t\n\r\f_\'"&#%]+/', '_', $id );
1013                         $id = trim( $id, '_' );
1014                         if ( $id === '' ) {
1015                                 # Must have been all whitespace to start with.
1016                                 return '_';
1017                         } else {
1018                                 return $id;
1019                         }
1020                 }
1021
1022                 # HTML4-style escaping
1023                 static $replace = array(
1024                         '%3A' => ':',
1025                         '%' => '.'
1026                 );
1027
1028                 $id = urlencode( Sanitizer::decodeCharReferences( strtr( $id, ' ', '_' ) ) );
1029                 $id = str_replace( array_keys( $replace ), array_values( $replace ), $id );
1030
1031                 if ( !preg_match( '/^[a-zA-Z]/', $id )
1032                 && !in_array( 'noninitial', $options ) )  {
1033                         // Initial character must be a letter!
1034                         $id = "x$id";
1035                 }
1036                 return $id;
1037         }
1038
1039         /**
1040          * Given a value, escape it so that it can be used as a CSS class and
1041          * return it.
1042          *
1043          * @todo For extra validity, input should be validated UTF-8.
1044          *
1045          * @see http://www.w3.org/TR/CSS21/syndata.html Valid characters/format
1046          *
1047          * @param $class String
1048          * @return String
1049          */
1050         static function escapeClass( $class ) {
1051                 // Convert ugly stuff to underscores and kill underscores in ugly places
1052                 return rtrim(preg_replace(
1053                         array('/(^[0-9\\-])|[\\x00-\\x20!"#$%&\'()*+,.\\/:;<=>?@[\\]^`{|}~]|\\xC2\\xA0/','/_+/'),
1054                         '_',
1055                         $class ), '_');
1056         }
1057
1058         /**
1059          * Given HTML input, escape with htmlspecialchars but un-escape entites.
1060          * This allows (generally harmless) entities like &#160; to survive.
1061          *
1062          * @param $html String to escape
1063          * @return String: escaped input
1064          */
1065         static function escapeHtmlAllowEntities( $html ) {
1066                 $html = Sanitizer::decodeCharReferences( $html );
1067                 # It seems wise to escape ' as well as ", as a matter of course.  Can't
1068                 # hurt.
1069                 $html = htmlspecialchars( $html, ENT_QUOTES );
1070                 return $html;
1071         }
1072
1073         /**
1074          * Regex replace callback for armoring links against further processing.
1075          * @param $matches Array
1076          * @return string
1077          */
1078         private static function armorLinksCallback( $matches ) {
1079                 return str_replace( ':', '&#58;', $matches[1] );
1080         }
1081
1082         /**
1083          * Return an associative array of attribute names and values from
1084          * a partial tag string. Attribute names are forces to lowercase,
1085          * character references are decoded to UTF-8 text.
1086          *
1087          * @param $text String
1088          * @return Array
1089          */
1090         public static function decodeTagAttributes( $text ) {
1091                 if( trim( $text ) == '' ) {
1092                         return array();
1093                 }
1094
1095                 $attribs = array();
1096                 $pairs = array();
1097                 if( !preg_match_all(
1098                         MW_ATTRIBS_REGEX,
1099                         $text,
1100                         $pairs,
1101                         PREG_SET_ORDER ) ) {
1102                         return $attribs;
1103                 }
1104
1105                 foreach( $pairs as $set ) {
1106                         $attribute = strtolower( $set[1] );
1107                         $value = Sanitizer::getTagAttributeCallback( $set );
1108
1109                         // Normalize whitespace
1110                         $value = preg_replace( '/[\t\r\n ]+/', ' ', $value );
1111                         $value = trim( $value );
1112
1113                         // Decode character references
1114                         $attribs[$attribute] = Sanitizer::decodeCharReferences( $value );
1115                 }
1116                 return $attribs;
1117         }
1118
1119         /**
1120          * Pick the appropriate attribute value from a match set from the
1121          * MW_ATTRIBS_REGEX matches.
1122          *
1123          * @param $set Array
1124          * @return String
1125          */
1126         private static function getTagAttributeCallback( $set ) {
1127                 if( isset( $set[6] ) ) {
1128                         # Illegal #XXXXXX color with no quotes.
1129                         return $set[6];
1130                 } elseif( isset( $set[5] ) ) {
1131                         # No quotes.
1132                         return $set[5];
1133                 } elseif( isset( $set[4] ) ) {
1134                         # Single-quoted
1135                         return $set[4];
1136                 } elseif( isset( $set[3] ) ) {
1137                         # Double-quoted
1138                         return $set[3];
1139                 } elseif( !isset( $set[2] ) ) {
1140                         # In XHTML, attributes must have a value.
1141                         # For 'reduced' form, return explicitly the attribute name here.
1142                         return $set[1];
1143                 } else {
1144                         throw new MWException( "Tag conditions not met. This should never happen and is a bug." );
1145                 }
1146         }
1147
1148         /**
1149          * Normalize whitespace and character references in an XML source-
1150          * encoded text for an attribute value.
1151          *
1152          * See http://www.w3.org/TR/REC-xml/#AVNormalize for background,
1153          * but note that we're not returning the value, but are returning
1154          * XML source fragments that will be slapped into output.
1155          *
1156          * @param $text String
1157          * @return String
1158          */
1159         private static function normalizeAttributeValue( $text ) {
1160                 return str_replace( '"', '&quot;',
1161                         self::normalizeWhitespace(
1162                                 Sanitizer::normalizeCharReferences( $text ) ) );
1163         }
1164
1165         private static function normalizeWhitespace( $text ) {
1166                 return preg_replace(
1167                         '/\r\n|[\x20\x0d\x0a\x09]/',
1168                         ' ',
1169                         $text );
1170         }
1171
1172         /**
1173          * Normalizes whitespace in a section name, such as might be returned
1174          * by Parser::stripSectionName(), for use in the id's that are used for
1175          * section links.
1176          *
1177          * @param $section String
1178          * @return String
1179          */
1180         static function normalizeSectionNameWhitespace( $section ) {
1181                 return trim( preg_replace( '/[ _]+/', ' ', $section ) );
1182         }
1183
1184         /**
1185          * Ensure that any entities and character references are legal
1186          * for XML and XHTML specifically. Any stray bits will be
1187          * &amp;-escaped to result in a valid text fragment.
1188          *
1189          * a. any named char refs must be known in XHTML
1190          * b. any numeric char refs must be legal chars, not invalid or forbidden
1191          * c. use &#x, not &#X
1192          * d. fix or reject non-valid attributes
1193          *
1194          * @param $text String
1195          * @return String
1196          * @private
1197          */
1198         static function normalizeCharReferences( $text ) {
1199                 return preg_replace_callback(
1200                         MW_CHAR_REFS_REGEX,
1201                         array( 'Sanitizer', 'normalizeCharReferencesCallback' ),
1202                         $text );
1203         }
1204         /**
1205          * @param $matches String
1206          * @return String
1207          */
1208         static function normalizeCharReferencesCallback( $matches ) {
1209                 $ret = null;
1210                 if( $matches[1] != '' ) {
1211                         $ret = Sanitizer::normalizeEntity( $matches[1] );
1212                 } elseif( $matches[2] != '' ) {
1213                         $ret = Sanitizer::decCharReference( $matches[2] );
1214                 } elseif( $matches[3] != ''  ) {
1215                         $ret = Sanitizer::hexCharReference( $matches[3] );
1216                 } elseif( $matches[4] != '' ) {
1217                         $ret = Sanitizer::hexCharReference( $matches[4] );
1218                 }
1219                 if( is_null( $ret ) ) {
1220                         return htmlspecialchars( $matches[0] );
1221                 } else {
1222                         return $ret;
1223                 }
1224         }
1225
1226         /**
1227          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1228          * return the named entity reference as is. If the entity is a
1229          * MediaWiki-specific alias, returns the HTML equivalent. Otherwise,
1230          * returns HTML-escaped text of pseudo-entity source (eg &amp;foo;)
1231          *
1232          * @param $name String
1233          * @return String
1234          */
1235         static function normalizeEntity( $name ) {
1236                 global $wgHtmlEntities, $wgHtmlEntityAliases;
1237                 if ( isset( $wgHtmlEntityAliases[$name] ) ) {
1238                         return "&{$wgHtmlEntityAliases[$name]};";
1239                 } elseif( isset( $wgHtmlEntities[$name] ) ) {
1240                         return "&$name;";
1241                 } else {
1242                         return "&amp;$name;";
1243                 }
1244         }
1245
1246         static function decCharReference( $codepoint ) {
1247                 $point = intval( $codepoint );
1248                 if( Sanitizer::validateCodepoint( $point ) ) {
1249                         return sprintf( '&#%d;', $point );
1250                 } else {
1251                         return null;
1252                 }
1253         }
1254
1255         static function hexCharReference( $codepoint ) {
1256                 $point = hexdec( $codepoint );
1257                 if( Sanitizer::validateCodepoint( $point ) ) {
1258                         return sprintf( '&#x%x;', $point );
1259                 } else {
1260                         return null;
1261                 }
1262         }
1263
1264         /**
1265          * Returns true if a given Unicode codepoint is a valid character in XML.
1266          * @param $codepoint Integer
1267          * @return Boolean
1268          */
1269         private static function validateCodepoint( $codepoint ) {
1270                 return ($codepoint ==    0x09)
1271                         || ($codepoint ==    0x0a)
1272                         || ($codepoint ==    0x0d)
1273                         || ($codepoint >=    0x20 && $codepoint <=   0xd7ff)
1274                         || ($codepoint >=  0xe000 && $codepoint <=   0xfffd)
1275                         || ($codepoint >= 0x10000 && $codepoint <= 0x10ffff);
1276         }
1277
1278         /**
1279          * Decode any character references, numeric or named entities,
1280          * in the text and return a UTF-8 string.
1281          *
1282          * @param $text String
1283          * @return String
1284          */
1285         public static function decodeCharReferences( $text ) {
1286                 return preg_replace_callback(
1287                         MW_CHAR_REFS_REGEX,
1288                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1289                         $text );
1290         }
1291
1292         /**
1293          * Decode any character references, numeric or named entities,
1294          * in the next and normalize the resulting string. (bug 14952)
1295          *
1296          * This is useful for page titles, not for text to be displayed,
1297          * MediaWiki allows HTML entities to escape normalization as a feature.
1298          *
1299          * @param $text String (already normalized, containing entities)
1300          * @return String (still normalized, without entities)
1301          */
1302         public static function decodeCharReferencesAndNormalize( $text ) {
1303                 global $wgContLang;
1304                 $text = preg_replace_callback(
1305                         MW_CHAR_REFS_REGEX,
1306                         array( 'Sanitizer', 'decodeCharReferencesCallback' ),
1307                         $text, /* limit */ -1, $count );
1308
1309                 if ( $count ) {
1310                         return $wgContLang->normalize( $text );
1311                 } else {
1312                         return $text;
1313                 }
1314         }
1315
1316         /**
1317          * @param $matches String
1318          * @return String
1319          */
1320         static function decodeCharReferencesCallback( $matches ) {
1321                 if( $matches[1] != '' ) {
1322                         return Sanitizer::decodeEntity( $matches[1] );
1323                 } elseif( $matches[2] != '' ) {
1324                         return  Sanitizer::decodeChar( intval( $matches[2] ) );
1325                 } elseif( $matches[3] != ''  ) {
1326                         return  Sanitizer::decodeChar( hexdec( $matches[3] ) );
1327                 } elseif( $matches[4] != '' ) {
1328                         return  Sanitizer::decodeChar( hexdec( $matches[4] ) );
1329                 }
1330                 # Last case should be an ampersand by itself
1331                 return $matches[0];
1332         }
1333
1334         /**
1335          * Return UTF-8 string for a codepoint if that is a valid
1336          * character reference, otherwise U+FFFD REPLACEMENT CHARACTER.
1337          * @param $codepoint Integer
1338          * @return String
1339          * @private
1340          */
1341         static function decodeChar( $codepoint ) {
1342                 if( Sanitizer::validateCodepoint( $codepoint ) ) {
1343                         return codepointToUtf8( $codepoint );
1344                 } else {
1345                         return UTF8_REPLACEMENT;
1346                 }
1347         }
1348
1349         /**
1350          * If the named entity is defined in the HTML 4.0/XHTML 1.0 DTD,
1351          * return the UTF-8 encoding of that character. Otherwise, returns
1352          * pseudo-entity source (eg &foo;)
1353          *
1354          * @param $name Strings
1355          * @return String
1356          */
1357         static function decodeEntity( $name ) {
1358                 global $wgHtmlEntities, $wgHtmlEntityAliases;
1359                 if ( isset( $wgHtmlEntityAliases[$name] ) ) {
1360                         $name = $wgHtmlEntityAliases[$name];
1361                 }
1362                 if( isset( $wgHtmlEntities[$name] ) ) {
1363                         return codepointToUtf8( $wgHtmlEntities[$name] );
1364                 } else {
1365                         return "&$name;";
1366                 }
1367         }
1368
1369         /**
1370          * Fetch the whitelist of acceptable attributes for a given element name.
1371          *
1372          * @param $element String
1373          * @return Array
1374          */
1375         static function attributeWhitelist( $element ) {
1376                 static $list;
1377                 if( !isset( $list ) ) {
1378                         $list = Sanitizer::setupAttributeWhitelist();
1379                 }
1380                 return isset( $list[$element] )
1381                         ? $list[$element]
1382                         : array();
1383         }
1384
1385         /**
1386          * Foreach array key (an allowed HTML element), return an array
1387          * of allowed attributes
1388          * @return Array
1389          */
1390         static function setupAttributeWhitelist() {
1391                 global $wgAllowRdfaAttributes, $wgHtml5, $wgAllowMicrodataAttributes;
1392
1393                 $common = array( 'id', 'class', 'lang', 'dir', 'title', 'style' );
1394
1395                 if ( $wgAllowRdfaAttributes ) {
1396                         #RDFa attributes as specified in section 9 of http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014
1397                         $common = array_merge( $common, array(
1398                             'about', 'property', 'resource', 'datatype', 'typeof',
1399                         ) );
1400                 }
1401
1402                 if ( $wgHtml5 && $wgAllowMicrodataAttributes ) {
1403                         # add HTML5 microdata tages as pecified by http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#the-microdata-model
1404                         $common = array_merge( $common, array(
1405                             'itemid', 'itemprop', 'itemref', 'itemscope', 'itemtype'
1406                         ) );
1407                 }
1408
1409                 $block = array_merge( $common, array( 'align' ) );
1410                 $tablealign = array( 'align', 'char', 'charoff', 'valign' );
1411                 $tablecell = array( 'abbr',
1412                                     'axis',
1413                                     'headers',
1414                                     'scope',
1415                                     'rowspan',
1416                                     'colspan',
1417                                     'nowrap', # deprecated
1418                                     'width',  # deprecated
1419                                     'height', # deprecated
1420                                     'bgcolor' # deprecated
1421                                     );
1422
1423                 # Numbers refer to sections in HTML 4.01 standard describing the element.
1424                 # See: http://www.w3.org/TR/html4/
1425                 $whitelist = array (
1426                         # 7.5.4
1427                         'div'        => $block,
1428                         'center'     => $common, # deprecated
1429                         'span'       => $block, # ??
1430
1431                         # 7.5.5
1432                         'h1'         => $block,
1433                         'h2'         => $block,
1434                         'h3'         => $block,
1435                         'h4'         => $block,
1436                         'h5'         => $block,
1437                         'h6'         => $block,
1438
1439                         # 7.5.6
1440                         # address
1441
1442                         # 8.2.4
1443                         # bdo
1444
1445                         # 9.2.1
1446                         'em'         => $common,
1447                         'strong'     => $common,
1448                         'cite'       => $common,
1449                         'dfn'        => $common,
1450                         'code'       => $common,
1451                         # samp
1452                         # kbd
1453                         'var'        => $common,
1454                         'abbr'       => $common,
1455                         # acronym
1456
1457                         # 9.2.2
1458                         'blockquote' => array_merge( $common, array( 'cite' ) ),
1459                         # q
1460
1461                         # 9.2.3
1462                         'sub'        => $common,
1463                         'sup'        => $common,
1464
1465                         # 9.3.1
1466                         'p'          => $block,
1467
1468                         # 9.3.2
1469                         'br'         => array( 'id', 'class', 'title', 'style', 'clear' ),
1470
1471                         # 9.3.4
1472                         'pre'        => array_merge( $common, array( 'width' ) ),
1473
1474                         # 9.4
1475                         'ins'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1476                         'del'        => array_merge( $common, array( 'cite', 'datetime' ) ),
1477
1478                         # 10.2
1479                         'ul'         => array_merge( $common, array( 'type' ) ),
1480                         'ol'         => array_merge( $common, array( 'type', 'start' ) ),
1481                         'li'         => array_merge( $common, array( 'type', 'value' ) ),
1482
1483                         # 10.3
1484                         'dl'         => $common,
1485                         'dd'         => $common,
1486                         'dt'         => $common,
1487
1488                         # 11.2.1
1489                         'table'      => array_merge( $common,
1490                                                                 array( 'summary', 'width', 'border', 'frame',
1491                                                                                 'rules', 'cellspacing', 'cellpadding',
1492                                                                                 'align', 'bgcolor',
1493                                                                 ) ),
1494
1495                         # 11.2.2
1496                         'caption'    => array_merge( $common, array( 'align' ) ),
1497
1498                         # 11.2.3
1499                         'thead'      => array_merge( $common, $tablealign ),
1500                         'tfoot'      => array_merge( $common, $tablealign ),
1501                         'tbody'      => array_merge( $common, $tablealign ),
1502
1503                         # 11.2.4
1504                         'colgroup'   => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1505                         'col'        => array_merge( $common, array( 'span', 'width' ), $tablealign ),
1506
1507                         # 11.2.5
1508                         'tr'         => array_merge( $common, array( 'bgcolor' ), $tablealign ),
1509
1510                         # 11.2.6
1511                         'td'         => array_merge( $common, $tablecell, $tablealign ),
1512                         'th'         => array_merge( $common, $tablecell, $tablealign ),
1513
1514                         # 12.2 # NOTE: <a> is not allowed directly, but the attrib whitelist is used from the Parser object
1515                         'a'          => array_merge( $common, array( 'href', 'rel', 'rev' ) ), # rel/rev esp. for RDFa
1516
1517                         # 13.2
1518                         # Not usually allowed, but may be used for extension-style hooks
1519                         # such as <math> when it is rasterized, or if $wgAllowImageTag is
1520                         # true
1521                         'img'        => array_merge( $common, array( 'alt', 'src', 'width', 'height' ) ),
1522
1523                         # 15.2.1
1524                         'tt'         => $common,
1525                         'b'          => $common,
1526                         'i'          => $common,
1527                         'big'        => $common,
1528                         'small'      => $common,
1529                         'strike'     => $common,
1530                         's'          => $common,
1531                         'u'          => $common,
1532
1533                         # 15.2.2
1534                         'font'       => array_merge( $common, array( 'size', 'color', 'face' ) ),
1535                         # basefont
1536
1537                         # 15.3
1538                         'hr'         => array_merge( $common, array( 'noshade', 'size', 'width' ) ),
1539
1540                         # XHTML Ruby annotation text module, simple ruby only.
1541                         # http://www.w3c.org/TR/ruby/
1542                         'ruby'       => $common,
1543                         # rbc
1544                         # rtc
1545                         'rb'         => $common,
1546                         'rt'         => $common, #array_merge( $common, array( 'rbspan' ) ),
1547                         'rp'         => $common,
1548
1549                         # MathML root element, where used for extensions
1550                         # 'title' may not be 100% valid here; it's XHTML
1551                         # http://www.w3.org/TR/REC-MathML/
1552                         'math'       => array( 'class', 'style', 'id', 'title' ),
1553                         );
1554                 return $whitelist;
1555         }
1556
1557         /**
1558          * Take a fragment of (potentially invalid) HTML and return
1559          * a version with any tags removed, encoded as plain text.
1560          *
1561          * Warning: this return value must be further escaped for literal
1562          * inclusion in HTML output as of 1.10!
1563          *
1564          * @param $text String: HTML fragment
1565          * @return String
1566          */
1567         static function stripAllTags( $text ) {
1568                 # Actual <tags>
1569                 $text = StringUtils::delimiterReplace( '<', '>', '', $text );
1570
1571                 # Normalize &entities and whitespace
1572                 $text = self::decodeCharReferences( $text );
1573                 $text = self::normalizeWhitespace( $text );
1574
1575                 return $text;
1576         }
1577
1578         /**
1579          * Hack up a private DOCTYPE with HTML's standard entity declarations.
1580          * PHP 4 seemed to know these if you gave it an HTML doctype, but
1581          * PHP 5.1 doesn't.
1582          *
1583          * Use for passing XHTML fragments to PHP's XML parsing functions
1584          *
1585          * @return String
1586          */
1587         static function hackDocType() {
1588                 global $wgHtmlEntities;
1589                 $out = "<!DOCTYPE html [\n";
1590                 foreach( $wgHtmlEntities as $entity => $codepoint ) {
1591                         $out .= "<!ENTITY $entity \"&#$codepoint;\">";
1592                 }
1593                 $out .= "]>\n";
1594                 return $out;
1595         }
1596
1597         static function cleanUrl( $url ) {
1598                 # Normalize any HTML entities in input. They will be
1599                 # re-escaped by makeExternalLink().
1600                 $url = Sanitizer::decodeCharReferences( $url );
1601
1602                 # Escape any control characters introduced by the above step
1603                 $url = preg_replace( '/[\][<>"\\x00-\\x20\\x7F\|]/e', "urlencode('\\0')", $url );
1604
1605                 # Validate hostname portion
1606                 $matches = array();
1607                 if( preg_match( '!^([^:]+:)(//[^/]+)?(.*)$!iD', $url, $matches ) ) {
1608                         list( /* $whole */, $protocol, $host, $rest ) = $matches;
1609
1610                         // Characters that will be ignored in IDNs.
1611                         // http://tools.ietf.org/html/3454#section-3.1
1612                         // Strip them before further processing so blacklists and such work.
1613                         $strip = "/
1614                                 \\s|          # general whitespace
1615                                 \xc2\xad|     # 00ad SOFT HYPHEN
1616                                 \xe1\xa0\x86| # 1806 MONGOLIAN TODO SOFT HYPHEN
1617                                 \xe2\x80\x8b| # 200b ZERO WIDTH SPACE
1618                                 \xe2\x81\xa0| # 2060 WORD JOINER
1619                                 \xef\xbb\xbf| # feff ZERO WIDTH NO-BREAK SPACE
1620                                 \xcd\x8f|     # 034f COMBINING GRAPHEME JOINER
1621                                 \xe1\xa0\x8b| # 180b MONGOLIAN FREE VARIATION SELECTOR ONE
1622                                 \xe1\xa0\x8c| # 180c MONGOLIAN FREE VARIATION SELECTOR TWO
1623                                 \xe1\xa0\x8d| # 180d MONGOLIAN FREE VARIATION SELECTOR THREE
1624                                 \xe2\x80\x8c| # 200c ZERO WIDTH NON-JOINER
1625                                 \xe2\x80\x8d| # 200d ZERO WIDTH JOINER
1626                                 [\xef\xb8\x80-\xef\xb8\x8f] # fe00-fe00f VARIATION SELECTOR-1-16
1627                                 /xuD";
1628
1629                         $host = preg_replace( $strip, '', $host );
1630
1631                         // @todo Fixme: validate hostnames here
1632
1633                         return $protocol . $host . $rest;
1634                 } else {
1635                         return $url;
1636                 }
1637         }
1638
1639 }