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Developer Documentation
- Bug fixes for general core bugs in 4.2.x will end 22 April 2024 (12 months).
- Bug fixes for security issues in 4.2.x will end 7 October 2024 (18 months).
- PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.1.x is supported too.
/lib/htmlpurifier/HTMLPurifier/Lexer/ -> DOMLex.php (source)
1 <?php 2 3 /** 4 * Parser that uses PHP 5's DOM extension (part of the core). 5 * 6 * In PHP 5, the DOM XML extension was revamped into DOM and added to the core. 7 * It gives us a forgiving HTML parser, which we use to transform the HTML 8 * into a DOM, and then into the tokens. It is blazingly fast (for large 9 * documents, it performs twenty times faster than 10 * HTMLPurifier_Lexer_DirectLex,and is the default choice for PHP 5. 11 * 12 * @note Any empty elements will have empty tokens associated with them, even if 13 * this is prohibited by the spec. This is cannot be fixed until the spec 14 * comes into play. 15 * 16 * @note PHP's DOM extension does not actually parse any entities, we use 17 * our own function to do that. 18 * 19 * @warning DOM tends to drop whitespace, which may wreak havoc on indenting. 20 * If this is a huge problem, due to the fact that HTML is hand 21 * edited and you are unable to get a parser cache that caches the 22 * the output of HTML Purifier while keeping the original HTML lying 23 * around, you may want to run Tidy on the resulting output or use 24 * HTMLPurifier_DirectLex 25 */ 26 27 class HTMLPurifier_Lexer_DOMLex extends HTMLPurifier_Lexer 28 { 29 30 /** 31 * @type HTMLPurifier_TokenFactory 32 */ 33 private $factory; 34 35 public function __construct() 36 { 37 // setup the factory 38 parent::__construct(); 39 $this->factory = new HTMLPurifier_TokenFactory(); 40 } 41 42 /** 43 * @param string $html 44 * @param HTMLPurifier_Config $config 45 * @param HTMLPurifier_Context $context 46 * @return HTMLPurifier_Token[] 47 */ 48 public function tokenizeHTML($html, $config, $context) 49 { 50 $html = $this->normalize($html, $config, $context); 51 52 // attempt to armor stray angled brackets that cannot possibly 53 // form tags and thus are probably being used as emoticons 54 if ($config->get('Core.AggressivelyFixLt')) { 55 $char = '[^a-z!\/]'; 56 $comment = "/<!--(.*?)(-->|\z)/is"; 57 $html = preg_replace_callback($comment, array($this, 'callbackArmorCommentEntities'), $html); 58 do { 59 $old = $html; 60 $html = preg_replace("/<($char)/i", '<\\1', $html); 61 } while ($html !== $old); 62 $html = preg_replace_callback($comment, array($this, 'callbackUndoCommentSubst'), $html); // fix comments 63 } 64 65 // preprocess html, essential for UTF-8 66 $html = $this->wrapHTML($html, $config, $context); 67 68 $doc = new DOMDocument(); 69 $doc->encoding = 'UTF-8'; // theoretically, the above has this covered 70 71 $options = 0; 72 if ($config->get('Core.AllowParseManyTags') && defined('LIBXML_PARSEHUGE')) { 73 $options |= LIBXML_PARSEHUGE; 74 } 75 76 set_error_handler(array($this, 'muteErrorHandler')); 77 // loadHTML() fails on PHP 5.3 when second parameter is given 78 if ($options) { 79 $doc->loadHTML($html, $options); 80 } else { 81 $doc->loadHTML($html); 82 } 83 restore_error_handler(); 84 85 $body = $doc->getElementsByTagName('html')->item(0)-> // <html> 86 getElementsByTagName('body')->item(0); // <body> 87 88 $div = $body->getElementsByTagName('div')->item(0); // <div> 89 $tokens = array(); 90 $this->tokenizeDOM($div, $tokens, $config); 91 // If the div has a sibling, that means we tripped across 92 // a premature </div> tag. So remove the div we parsed, 93 // and then tokenize the rest of body. We can't tokenize 94 // the sibling directly as we'll lose the tags in that case. 95 if ($div->nextSibling) { 96 $body->removeChild($div); 97 $this->tokenizeDOM($body, $tokens, $config); 98 } 99 return $tokens; 100 } 101 102 /** 103 * Iterative function that tokenizes a node, putting it into an accumulator. 104 * To iterate is human, to recurse divine - L. Peter Deutsch 105 * @param DOMNode $node DOMNode to be tokenized. 106 * @param HTMLPurifier_Token[] $tokens Array-list of already tokenized tokens. 107 * @return HTMLPurifier_Token of node appended to previously passed tokens. 108 */ 109 protected function tokenizeDOM($node, &$tokens, $config) 110 { 111 $level = 0; 112 $nodes = array($level => new HTMLPurifier_Queue(array($node))); 113 $closingNodes = array(); 114 do { 115 while (!$nodes[$level]->isEmpty()) { 116 $node = $nodes[$level]->shift(); // FIFO 117 $collect = $level > 0 ? true : false; 118 $needEndingTag = $this->createStartNode($node, $tokens, $collect, $config); 119 if ($needEndingTag) { 120 $closingNodes[$level][] = $node; 121 } 122 if ($node->childNodes && $node->childNodes->length) { 123 $level++; 124 $nodes[$level] = new HTMLPurifier_Queue(); 125 foreach ($node->childNodes as $childNode) { 126 $nodes[$level]->push($childNode); 127 } 128 } 129 } 130 $level--; 131 if ($level && isset($closingNodes[$level])) { 132 while ($node = array_pop($closingNodes[$level])) { 133 $this->createEndNode($node, $tokens); 134 } 135 } 136 } while ($level > 0); 137 } 138 139 /** 140 * Portably retrieve the tag name of a node; deals with older versions 141 * of libxml like 2.7.6 142 * @param DOMNode $node 143 */ 144 protected function getTagName($node) 145 { 146 if (isset($node->tagName)) { 147 return $node->tagName; 148 } else if (isset($node->nodeName)) { 149 return $node->nodeName; 150 } else if (isset($node->localName)) { 151 return $node->localName; 152 } 153 return null; 154 } 155 156 /** 157 * Portably retrieve the data of a node; deals with older versions 158 * of libxml like 2.7.6 159 * @param DOMNode $node 160 */ 161 protected function getData($node) 162 { 163 if (isset($node->data)) { 164 return $node->data; 165 } else if (isset($node->nodeValue)) { 166 return $node->nodeValue; 167 } else if (isset($node->textContent)) { 168 return $node->textContent; 169 } 170 return null; 171 } 172 173 174 /** 175 * @param DOMNode $node DOMNode to be tokenized. 176 * @param HTMLPurifier_Token[] $tokens Array-list of already tokenized tokens. 177 * @param bool $collect Says whether or start and close are collected, set to 178 * false at first recursion because it's the implicit DIV 179 * tag you're dealing with. 180 * @return bool if the token needs an endtoken 181 * @todo data and tagName properties don't seem to exist in DOMNode? 182 */ 183 protected function createStartNode($node, &$tokens, $collect, $config) 184 { 185 // intercept non element nodes. WE MUST catch all of them, 186 // but we're not getting the character reference nodes because 187 // those should have been preprocessed 188 if ($node->nodeType === XML_TEXT_NODE) { 189 $data = $this->getData($node); // Handle variable data property 190 if ($data !== null) { 191 $tokens[] = $this->factory->createText($data); 192 } 193 return false; 194 } elseif ($node->nodeType === XML_CDATA_SECTION_NODE) { 195 // undo libxml's special treatment of <script> and <style> tags 196 $last = end($tokens); 197 $data = $node->data; 198 // (note $node->tagname is already normalized) 199 if ($last instanceof HTMLPurifier_Token_Start && ($last->name == 'script' || $last->name == 'style')) { 200 $new_data = trim($data); 201 if (substr($new_data, 0, 4) === '<!--') { 202 $data = substr($new_data, 4); 203 if (substr($data, -3) === '-->') { 204 $data = substr($data, 0, -3); 205 } else { 206 // Highly suspicious! Not sure what to do... 207 } 208 } 209 } 210 $tokens[] = $this->factory->createText($this->parseText($data, $config)); 211 return false; 212 } elseif ($node->nodeType === XML_COMMENT_NODE) { 213 // this is code is only invoked for comments in script/style in versions 214 // of libxml pre-2.6.28 (regular comments, of course, are still 215 // handled regularly) 216 $tokens[] = $this->factory->createComment($node->data); 217 return false; 218 } elseif ($node->nodeType !== XML_ELEMENT_NODE) { 219 // not-well tested: there may be other nodes we have to grab 220 return false; 221 } 222 $attr = $node->hasAttributes() ? $this->transformAttrToAssoc($node->attributes) : array(); 223 $tag_name = $this->getTagName($node); // Handle variable tagName property 224 if (empty($tag_name)) { 225 return (bool) $node->childNodes->length; 226 } 227 // We still have to make sure that the element actually IS empty 228 if (!$node->childNodes->length) { 229 if ($collect) { 230 $tokens[] = $this->factory->createEmpty($tag_name, $attr); 231 } 232 return false; 233 } else { 234 if ($collect) { 235 $tokens[] = $this->factory->createStart($tag_name, $attr); 236 } 237 return true; 238 } 239 } 240 241 /** 242 * @param DOMNode $node 243 * @param HTMLPurifier_Token[] $tokens 244 */ 245 protected function createEndNode($node, &$tokens) 246 { 247 $tag_name = $this->getTagName($node); // Handle variable tagName property 248 $tokens[] = $this->factory->createEnd($tag_name); 249 } 250 251 /** 252 * Converts a DOMNamedNodeMap of DOMAttr objects into an assoc array. 253 * 254 * @param DOMNamedNodeMap $node_map DOMNamedNodeMap of DOMAttr objects. 255 * @return array Associative array of attributes. 256 */ 257 protected function transformAttrToAssoc($node_map) 258 { 259 // NamedNodeMap is documented very well, so we're using undocumented 260 // features, namely, the fact that it implements Iterator and 261 // has a ->length attribute 262 if ($node_map->length === 0) { 263 return array(); 264 } 265 $array = array(); 266 foreach ($node_map as $attr) { 267 $array[$attr->name] = $attr->value; 268 } 269 return $array; 270 } 271 272 /** 273 * An error handler that mutes all errors 274 * @param int $errno 275 * @param string $errstr 276 */ 277 public function muteErrorHandler($errno, $errstr) 278 { 279 } 280 281 /** 282 * Callback function for undoing escaping of stray angled brackets 283 * in comments 284 * @param array $matches 285 * @return string 286 */ 287 public function callbackUndoCommentSubst($matches) 288 { 289 return '<!--' . strtr($matches[1], array('&' => '&', '<' => '<')) . $matches[2]; 290 } 291 292 /** 293 * Callback function that entity-izes ampersands in comments so that 294 * callbackUndoCommentSubst doesn't clobber them 295 * @param array $matches 296 * @return string 297 */ 298 public function callbackArmorCommentEntities($matches) 299 { 300 return '<!--' . str_replace('&', '&', $matches[1]) . $matches[2]; 301 } 302 303 /** 304 * Wraps an HTML fragment in the necessary HTML 305 * @param string $html 306 * @param HTMLPurifier_Config $config 307 * @param HTMLPurifier_Context $context 308 * @return string 309 */ 310 protected function wrapHTML($html, $config, $context, $use_div = true) 311 { 312 $def = $config->getDefinition('HTML'); 313 $ret = ''; 314 315 if (!empty($def->doctype->dtdPublic) || !empty($def->doctype->dtdSystem)) { 316 $ret .= '<!DOCTYPE html '; 317 if (!empty($def->doctype->dtdPublic)) { 318 $ret .= 'PUBLIC "' . $def->doctype->dtdPublic . '" '; 319 } 320 if (!empty($def->doctype->dtdSystem)) { 321 $ret .= '"' . $def->doctype->dtdSystem . '" '; 322 } 323 $ret .= '>'; 324 } 325 326 $ret .= '<html><head>'; 327 $ret .= '<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />'; 328 // No protection if $html contains a stray </div>! 329 $ret .= '</head><body>'; 330 if ($use_div) $ret .= '<div>'; 331 $ret .= $html; 332 if ($use_div) $ret .= '</div>'; 333 $ret .= '</body></html>'; 334 return $ret; 335 } 336 } 337 338 // vim: et sw=4 sts=4
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