extlib/HTMLPurifier/HTMLPurifier/Strategy/MakeWellFormed.php

   1 <?php
   2
   3 /**
   4  * Takes tokens makes them well-formed (balance end tags, etc.)
   5  *
   6  * Specification of the armor attributes this strategy uses:
   7  *
   8  *      - MakeWellFormed_TagClosedError: This armor field is used to
   9  *        suppress tag closed errors for certain tokens [TagClosedSuppress],
  10  *        in particular, if a tag was generated automatically by HTML
  11  *        Purifier, we may rely on our infrastructure to close it for us
  12  *        and shouldn't report an error to the user [TagClosedAuto].
  13  */
  14 class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
  15 {
  16
  17     /**
  18      * Array stream of tokens being processed.
  19      * @type HTMLPurifier_Token[]
  20      */
  21     protected $tokens;
  22
  23     /**
  24      * Current token.
  25      * @type HTMLPurifier_Token
  26      */
  27     protected $token;
  28
  29     /**
  30      * Zipper managing the true state.
  31      * @type HTMLPurifier_Zipper
  32      */
  33     protected $zipper;
  34
  35     /**
  36      * Current nesting of elements.
  37      * @type array
  38      */
  39     protected $stack;
  40
  41     /**
  42      * Injectors active in this stream processing.
  43      * @type HTMLPurifier_Injector[]
  44      */
  45     protected $injectors;
  46
  47     /**
  48      * Current instance of HTMLPurifier_Config.
  49      * @type HTMLPurifier_Config
  50      */
  51     protected $config;
  52
  53     /**
  54      * Current instance of HTMLPurifier_Context.
  55      * @type HTMLPurifier_Context
  56      */
  57     protected $context;
  58
  59     /**
  60      * @param HTMLPurifier_Token[] $tokens
  61      * @param HTMLPurifier_Config $config
  62      * @param HTMLPurifier_Context $context
  63      * @return HTMLPurifier_Token[]
  64      * @throws HTMLPurifier_Exception
  65      */
  66     public function execute($tokens, $config, $context)
  67     {
  68         $definition = $config->getHTMLDefinition();
  69
  70         // local variables
  71         $generator = new HTMLPurifier_Generator($config, $context);
  72         $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
  73         // used for autoclose early abortion
  74         $global_parent_allowed_elements = $definition->info_parent_def->child->getAllowedElements($config);
  75         $e = $context->get('ErrorCollector', true);
  76         $i = false; // injector index
  77         list($zipper, $token) = HTMLPurifier_Zipper::fromArray($tokens);
  78         if ($token === NULL) {
  79             return array();
  80         }
  81         $reprocess = false; // whether or not to reprocess the same token
  82         $stack = array();
  83
  84         // member variables
  85         $this->stack =& $stack;
  86         $this->tokens =& $tokens;
  87         $this->token =& $token;
  88         $this->zipper =& $zipper;
  89         $this->config = $config;
  90         $this->context = $context;
  91
  92         // context variables
  93         $context->register('CurrentNesting', $stack);
  94         $context->register('InputZipper', $zipper);
  95         $context->register('CurrentToken', $token);
  96
  97         // -- begin INJECTOR --
  98
  99         $this->injectors = array();
 100
 101         $injectors = $config->getBatch('AutoFormat');
 102         $def_injectors = $definition->info_injector;
 103         $custom_injectors = $injectors['Custom'];
 104         unset($injectors['Custom']); // special case
 105         foreach ($injectors as $injector => $b) {
 106             // XXX: Fix with a legitimate lookup table of enabled filters
 107             if (strpos($injector, '.') !== false) {
 108                 continue;
 109             }
 110             $injector = "HTMLPurifier_Injector_$injector";
 111             if (!$b) {
 112                 continue;
 113             }
 114             $this->injectors[] = new $injector;
 115         }
 116         foreach ($def_injectors as $injector) {
 117             // assumed to be objects
 118             $this->injectors[] = $injector;
 119         }
 120         foreach ($custom_injectors as $injector) {
 121             if (!$injector) {
 122                 continue;
 123             }
 124             if (is_string($injector)) {
 125                 $injector = "HTMLPurifier_Injector_$injector";
 126                 $injector = new $injector;
 127             }
 128             $this->injectors[] = $injector;
 129         }
 130
 131         // give the injectors references to the definition and context
 132         // variables for performance reasons
 133         foreach ($this->injectors as $ix => $injector) {
 134             $error = $injector->prepare($config, $context);
 135             if (!$error) {
 136                 continue;
 137             }
 138             array_splice($this->injectors, $ix, 1); // rm the injector
 139             trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
 140         }
 141
 142         // -- end INJECTOR --
 143
 144         // a note on reprocessing:
 145         //      In order to reduce code duplication, whenever some code needs
 146         //      to make HTML changes in order to make things "correct", the
 147         //      new HTML gets sent through the purifier, regardless of its
 148         //      status. This means that if we add a start token, because it
 149         //      was totally necessary, we don't have to update nesting; we just
 150         //      punt ($reprocess = true; continue;) and it does that for us.
 151
 152         // isset is in loop because $tokens size changes during loop exec
 153         for (;;
 154              // only increment if we don't need to reprocess
 155              $reprocess ? $reprocess = false : $token = $zipper->next($token)) {
 156
 157             // check for a rewind
 158             if (is_int($i)) {
 159                 // possibility: disable rewinding if the current token has a
 160                 // rewind set on it already. This would offer protection from
 161                 // infinite loop, but might hinder some advanced rewinding.
 162                 $rewind_offset = $this->injectors[$i]->getRewindOffset();
 163                 if (is_int($rewind_offset)) {
 164                     for ($j = 0; $j < $rewind_offset; $j++) {
 165                         if (empty($zipper->front)) break;
 166                         $token = $zipper->prev($token);
 167                         // indicate that other injectors should not process this token,
 168                         // but we need to reprocess it
 169                         unset($token->skip[$i]);
 170                         $token->rewind = $i;
 171                         if ($token instanceof HTMLPurifier_Token_Start) {
 172                             array_pop($this->stack);
 173                         } elseif ($token instanceof HTMLPurifier_Token_End) {
 174                             $this->stack[] = $token->start;
 175                         }
 176                     }
 177                 }
 178                 $i = false;
 179             }
 180
 181             // handle case of document end
 182             if ($token === NULL) {
 183                 // kill processing if stack is empty
 184                 if (empty($this->stack)) {
 185                     break;
 186                 }
 187
 188                 // peek
 189                 $top_nesting = array_pop($this->stack);
 190                 $this->stack[] = $top_nesting;
 191
 192                 // send error [TagClosedSuppress]
 193                 if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
 194                     $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
 195                 }
 196
 197                 // append, don't splice, since this is the end
 198                 $token = new HTMLPurifier_Token_End($top_nesting->name);
 199
 200                 // punt!
 201                 $reprocess = true;
 202                 continue;
 203             }
 204
 205             //echo '<br>'; printZipper($zipper, $token);//printTokens($this->stack);
 206             //flush();
 207
 208             // quick-check: if it's not a tag, no need to process
 209             if (empty($token->is_tag)) {
 210                 if ($token instanceof HTMLPurifier_Token_Text) {
 211                     foreach ($this->injectors as $i => $injector) {
 212                         if (isset($token->skip[$i])) {
 213                             continue;
 214                         }
 215                         if ($token->rewind !== null && $token->rewind !== $i) {
 216                             continue;
 217                         }
 218                         // XXX fuckup
 219                         $r = $token;
 220                         $injector->handleText($r);
 221                         $token = $this->processToken($r, $i);
 222                         $reprocess = true;
 223                         break;
 224                     }
 225                 }
 226                 // another possibility is a comment
 227                 continue;
 228             }
 229
 230             if (isset($definition->info[$token->name])) {
 231                 $type = $definition->info[$token->name]->child->type;
 232             } else {
 233                 $type = false; // Type is unknown, treat accordingly
 234             }
 235
 236             // quick tag checks: anything that's *not* an end tag
 237             $ok = false;
 238             if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
 239                 // claims to be a start tag but is empty
 240                 $token = new HTMLPurifier_Token_Empty(
 241                     $token->name,
 242                     $token->attr,
 243                     $token->line,
 244                     $token->col,
 245                     $token->armor
 246                 );
 247                 $ok = true;
 248             } elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
 249                 // claims to be empty but really is a start tag
 250                 // NB: this assignment is required
 251                 $old_token = $token;
 252                 $token = new HTMLPurifier_Token_End($token->name);
 253                 $token = $this->insertBefore(
 254                     new HTMLPurifier_Token_Start($old_token->name, $old_token->attr, $old_token->line, $old_token->col, $old_token->armor)
 255                 );
 256                 // punt (since we had to modify the input stream in a non-trivial way)
 257                 $reprocess = true;
 258                 continue;
 259             } elseif ($token instanceof HTMLPurifier_Token_Empty) {
 260                 // real empty token
 261                 $ok = true;
 262             } elseif ($token instanceof HTMLPurifier_Token_Start) {
 263                 // start tag
 264
 265                 // ...unless they also have to close their parent
 266                 if (!empty($this->stack)) {
 267
 268                     // Performance note: you might think that it's rather
 269                     // inefficient, recalculating the autoclose information
 270                     // for every tag that a token closes (since when we
 271                     // do an autoclose, we push a new token into the
 272                     // stream and then /process/ that, before
 273                     // re-processing this token.)  But this is
 274                     // necessary, because an injector can make an
 275                     // arbitrary transformations to the autoclosing
 276                     // tokens we introduce, so things may have changed
 277                     // in the meantime.  Also, doing the inefficient thing is
 278                     // "easy" to reason about (for certain perverse definitions
 279                     // of "easy")
 280
 281                     $parent = array_pop($this->stack);
 282                     $this->stack[] = $parent;
 283
 284                     $parent_def = null;
 285                     $parent_elements = null;
 286                     $autoclose = false;
 287                     if (isset($definition->info[$parent->name])) {
 288                         $parent_def = $definition->info[$parent->name];
 289                         $parent_elements = $parent_def->child->getAllowedElements($config);
 290                         $autoclose = !isset($parent_elements[$token->name]);
 291                     }
 292
 293                     if ($autoclose && $definition->info[$token->name]->wrap) {
 294                         // Check if an element can be wrapped by another
 295                         // element to make it valid in a context (for
 296                         // example, <ul><ul> needs a <li> in between)
 297                         $wrapname = $definition->info[$token->name]->wrap;
 298                         $wrapdef = $definition->info[$wrapname];
 299                         $elements = $wrapdef->child->getAllowedElements($config);
 300                         if (isset($elements[$token->name]) && isset($parent_elements[$wrapname])) {
 301                             $newtoken = new HTMLPurifier_Token_Start($wrapname);
 302                             $token = $this->insertBefore($newtoken);
 303                             $reprocess = true;
 304                             continue;
 305                         }
 306                     }
 307
 308                     $carryover = false;
 309                     if ($autoclose && $parent_def->formatting) {
 310                         $carryover = true;
 311                     }
 312
 313                     if ($autoclose) {
 314                         // check if this autoclose is doomed to fail
 315                         // (this rechecks $parent, which his harmless)
 316                         $autoclose_ok = isset($global_parent_allowed_elements[$token->name]);
 317                         if (!$autoclose_ok) {
 318                             foreach ($this->stack as $ancestor) {
 319                                 $elements = $definition->info[$ancestor->name]->child->getAllowedElements($config);
 320                                 if (isset($elements[$token->name])) {
 321                                     $autoclose_ok = true;
 322                                     break;
 323                                 }
 324                                 if ($definition->info[$token->name]->wrap) {
 325                                     $wrapname = $definition->info[$token->name]->wrap;
 326                                     $wrapdef = $definition->info[$wrapname];
 327                                     $wrap_elements = $wrapdef->child->getAllowedElements($config);
 328                                     if (isset($wrap_elements[$token->name]) && isset($elements[$wrapname])) {
 329                                         $autoclose_ok = true;
 330                                         break;
 331                                     }
 332                                 }
 333                             }
 334                         }
 335                         if ($autoclose_ok) {
 336                             // errors need to be updated
 337                             $new_token = new HTMLPurifier_Token_End($parent->name);
 338                             $new_token->start = $parent;
 339                             // [TagClosedSuppress]
 340                             if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
 341                                 if (!$carryover) {
 342                                     $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
 343                                 } else {
 344                                     $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
 345                                 }
 346                             }
 347                             if ($carryover) {
 348                                 $element = clone $parent;
 349                                 // [TagClosedAuto]
 350                                 $element->armor['MakeWellFormed_TagClosedError'] = true;
 351                                 $element->carryover = true;
 352                                 $token = $this->processToken(array($new_token, $token, $element));
 353                             } else {
 354                                 $token = $this->insertBefore($new_token);
 355                             }
 356                         } else {
 357                             $token = $this->remove();
 358                         }
 359                         $reprocess = true;
 360                         continue;
 361                     }
 362
 363                 }
 364                 $ok = true;
 365             }
 366
 367             if ($ok) {
 368                 foreach ($this->injectors as $i => $injector) {
 369                     if (isset($token->skip[$i])) {
 370                         continue;
 371                     }
 372                     if ($token->rewind !== null && $token->rewind !== $i) {
 373                         continue;
 374                     }
 375                     $r = $token;
 376                     $injector->handleElement($r);
 377                     $token = $this->processToken($r, $i);
 378                     $reprocess = true;
 379                     break;
 380                 }
 381                 if (!$reprocess) {
 382                     // ah, nothing interesting happened; do normal processing
 383                     if ($token instanceof HTMLPurifier_Token_Start) {
 384                         $this->stack[] = $token;
 385                     } elseif ($token instanceof HTMLPurifier_Token_End) {
 386                         throw new HTMLPurifier_Exception(
 387                             'Improper handling of end tag in start code; possible error in MakeWellFormed'
 388                         );
 389                     }
 390                 }
 391                 continue;
 392             }
 393
 394             // sanity check: we should be dealing with a closing tag
 395             if (!$token instanceof HTMLPurifier_Token_End) {
 396                 throw new HTMLPurifier_Exception('Unaccounted for tag token in input stream, bug in HTML Purifier');
 397             }
 398
 399             // make sure that we have something open
 400             if (empty($this->stack)) {
 401                 if ($escape_invalid_tags) {
 402                     if ($e) {
 403                         $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
 404                     }
 405                     $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
 406                 } else {
 407                     if ($e) {
 408                         $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
 409                     }
 410                     $token = $this->remove();
 411                 }
 412                 $reprocess = true;
 413                 continue;
 414             }
 415
 416             // first, check for the simplest case: everything closes neatly.
 417             // Eventually, everything passes through here; if there are problems
 418             // we modify the input stream accordingly and then punt, so that
 419             // the tokens get processed again.
 420             $current_parent = array_pop($this->stack);
 421             if ($current_parent->name == $token->name) {
 422                 $token->start = $current_parent;
 423                 foreach ($this->injectors as $i => $injector) {
 424                     if (isset($token->skip[$i])) {
 425                         continue;
 426                     }
 427                     if ($token->rewind !== null && $token->rewind !== $i) {
 428                         continue;
 429                     }
 430                     $r = $token;
 431                     $injector->handleEnd($r);
 432                     $token = $this->processToken($r, $i);
 433                     $this->stack[] = $current_parent;
 434                     $reprocess = true;
 435                     break;
 436                 }
 437                 continue;
 438             }
 439
 440             // okay, so we're trying to close the wrong tag
 441
 442             // undo the pop previous pop
 443             $this->stack[] = $current_parent;
 444
 445             // scroll back the entire nest, trying to find our tag.
 446             // (feature could be to specify how far you'd like to go)
 447             $size = count($this->stack);
 448             // -2 because -1 is the last element, but we already checked that
 449             $skipped_tags = false;
 450             for ($j = $size - 2; $j >= 0; $j--) {
 451                 if ($this->stack[$j]->name == $token->name) {
 452                     $skipped_tags = array_slice($this->stack, $j);
 453                     break;
 454                 }
 455             }
 456
 457             // we didn't find the tag, so remove
 458             if ($skipped_tags === false) {
 459                 if ($escape_invalid_tags) {
 460                     if ($e) {
 461                         $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
 462                     }
 463                     $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
 464                 } else {
 465                     if ($e) {
 466                         $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
 467                     }
 468                     $token = $this->remove();
 469                 }
 470                 $reprocess = true;
 471                 continue;
 472             }
 473
 474             // do errors, in REVERSE $j order: a,b,c with </a></b></c>
 475             $c = count($skipped_tags);
 476             if ($e) {
 477                 for ($j = $c - 1; $j > 0; $j--) {
 478                     // notice we exclude $j == 0, i.e. the current ending tag, from
 479                     // the errors... [TagClosedSuppress]
 480                     if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
 481                         $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
 482                     }
 483                 }
 484             }
 485
 486             // insert tags, in FORWARD $j order: c,b,a with </a></b></c>
 487             $replace = array($token);
 488             for ($j = 1; $j < $c; $j++) {
 489                 // ...as well as from the insertions
 490                 $new_token = new HTMLPurifier_Token_End($skipped_tags[$j]->name);
 491                 $new_token->start = $skipped_tags[$j];
 492                 array_unshift($replace, $new_token);
 493                 if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
 494                     // [TagClosedAuto]
 495                     $element = clone $skipped_tags[$j];
 496                     $element->carryover = true;
 497                     $element->armor['MakeWellFormed_TagClosedError'] = true;
 498                     $replace[] = $element;
 499                 }
 500             }
 501             $token = $this->processToken($replace);
 502             $reprocess = true;
 503             continue;
 504         }
 505
 506         $context->destroy('CurrentToken');
 507         $context->destroy('CurrentNesting');
 508         $context->destroy('InputZipper');
 509
 510         unset($this->injectors, $this->stack, $this->tokens);
 511         return $zipper->toArray($token);
 512     }
 513
 514     /**
 515      * Processes arbitrary token values for complicated substitution patterns.
 516      * In general:
 517      *
 518      * If $token is an array, it is a list of tokens to substitute for the
 519      * current token. These tokens then get individually processed. If there
 520      * is a leading integer in the list, that integer determines how many
 521      * tokens from the stream should be removed.
 522      *
 523      * If $token is a regular token, it is swapped with the current token.
 524      *
 525      * If $token is false, the current token is deleted.
 526      *
 527      * If $token is an integer, that number of tokens (with the first token
 528      * being the current one) will be deleted.
 529      *
 530      * @param HTMLPurifier_Token|array|int|bool $token Token substitution value
 531      * @param HTMLPurifier_Injector|int $injector Injector that performed the substitution; default is if
 532      *        this is not an injector related operation.
 533      * @throws HTMLPurifier_Exception
 534      */
 535     protected function processToken($token, $injector = -1)
 536     {
 537         // normalize forms of token
 538         if (is_object($token)) {
 539             $token = array(1, $token);
 540         }
 541         if (is_int($token)) {
 542             $token = array($token);
 543         }
 544         if ($token === false) {
 545             $token = array(1);
 546         }
 547         if (!is_array($token)) {
 548             throw new HTMLPurifier_Exception('Invalid token type from injector');
 549         }
 550         if (!is_int($token[0])) {
 551             array_unshift($token, 1);
 552         }
 553         if ($token[0] === 0) {
 554             throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
 555         }
 556
 557         // $token is now an array with the following form:
 558         // array(number nodes to delete, new node 1, new node 2, ...)
 559
 560         $delete = array_shift($token);
 561         list($old, $r) = $this->zipper->splice($this->token, $delete, $token);
 562
 563         if ($injector > -1) {
 564             // determine appropriate skips
 565             $oldskip = isset($old[0]) ? $old[0]->skip : array();
 566             foreach ($token as $object) {
 567                 $object->skip = $oldskip;
 568                 $object->skip[$injector] = true;
 569             }
 570         }
 571
 572         return $r;
 573
 574     }
 575
 576     /**
 577      * Inserts a token before the current token. Cursor now points to
 578      * this token.  You must reprocess after this.
 579      * @param HTMLPurifier_Token $token
 580      */
 581     private function insertBefore($token)
 582     {
 583         // NB not $this->zipper->insertBefore(), due to positioning
 584         // differences
 585         $splice = $this->zipper->splice($this->token, 0, array($token));
 586
 587         return $splice[1];
 588     }
 589
 590     /**
 591      * Removes current token. Cursor now points to new token occupying previously
 592      * occupied space.  You must reprocess after this.
 593      */
 594     private function remove()
 595     {
 596         return $this->zipper->delete();
 597     }
 598 }
 599
 600 // vim: et sw=4 sts=4