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- <?php
- namespace Drupal\Component\Utility;
- /**
- * Provides DOMDocument helpers for parsing and serializing HTML strings.
- *
- * @ingroup utility
- */
- class Html {
- /**
- * An array of previously cleaned HTML classes.
- *
- * @var array
- */
- protected static $classes = [];
- /**
- * An array of the initial IDs used in one request.
- *
- * @var array
- */
- protected static $seenIdsInit;
- /**
- * An array of IDs, including incremented versions when an ID is duplicated.
- * @var array
- */
- protected static $seenIds;
- /**
- * Stores whether the current request was sent via AJAX.
- *
- * @var bool
- */
- protected static $isAjax = FALSE;
- /**
- * All attributes that may contain URIs.
- *
- * - The attributes 'code' and 'codebase' are omitted, because they only exist
- * for the <applet> tag. The time of Java applets has passed.
- * - The attribute 'icon' is omitted, because no browser implements the
- * <command> tag anymore.
- * See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/command.
- * - The 'manifest' attribute is omitted because it only exists for the <html>
- * tag. That tag only makes sense in a HTML-served-as-HTML context, in which
- * case relative URLs are guaranteed to work.
- *
- * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes
- * @see https://stackoverflow.com/questions/2725156/complete-list-of-html-tag-attributes-which-have-a-url-value
- *
- * @var string[]
- */
- protected static $uriAttributes = ['href', 'poster', 'src', 'cite', 'data', 'action', 'formaction', 'srcset', 'about'];
- /**
- * Prepares a string for use as a valid class name.
- *
- * Do not pass one string containing multiple classes as they will be
- * incorrectly concatenated with dashes, i.e. "one two" will become "one-two".
- *
- * @param mixed $class
- * The class name to clean. It can be a string or anything that can be cast
- * to string.
- *
- * @return string
- * The cleaned class name.
- */
- public static function getClass($class) {
- $class = (string) $class;
- if (!isset(static::$classes[$class])) {
- static::$classes[$class] = static::cleanCssIdentifier(mb_strtolower($class));
- }
- return static::$classes[$class];
- }
- /**
- * Prepares a string for use as a CSS identifier (element, class, or ID name).
- *
- * Link below shows the syntax for valid CSS identifiers (including element
- * names, classes, and IDs in selectors).
- *
- * @see http://www.w3.org/TR/CSS21/syndata.html#characters
- *
- * @param string $identifier
- * The identifier to clean.
- * @param array $filter
- * An array of string replacements to use on the identifier.
- *
- * @return string
- * The cleaned identifier.
- */
- public static function cleanCssIdentifier($identifier, array $filter = [
- ' ' => '-',
- '_' => '-',
- '/' => '-',
- '[' => '-',
- ']' => '',
- ]) {
- // We could also use strtr() here but its much slower than str_replace(). In
- // order to keep '__' to stay '__' we first replace it with a different
- // placeholder after checking that it is not defined as a filter.
- $double_underscore_replacements = 0;
- if (!isset($filter['__'])) {
- $identifier = str_replace('__', '##', $identifier, $double_underscore_replacements);
- }
- $identifier = str_replace(array_keys($filter), array_values($filter), $identifier);
- // Replace temporary placeholder '##' with '__' only if the original
- // $identifier contained '__'.
- if ($double_underscore_replacements > 0) {
- $identifier = str_replace('##', '__', $identifier);
- }
- // Valid characters in a CSS identifier are:
- // - the hyphen (U+002D)
- // - a-z (U+0030 - U+0039)
- // - A-Z (U+0041 - U+005A)
- // - the underscore (U+005F)
- // - 0-9 (U+0061 - U+007A)
- // - ISO 10646 characters U+00A1 and higher
- // We strip out any character not in the above list.
- $identifier = preg_replace('/[^\x{002D}\x{0030}-\x{0039}\x{0041}-\x{005A}\x{005F}\x{0061}-\x{007A}\x{00A1}-\x{FFFF}]/u', '', $identifier);
- // Identifiers cannot start with a digit, two hyphens, or a hyphen followed by a digit.
- $identifier = preg_replace([
- '/^[0-9]/',
- '/^(-[0-9])|^(--)/',
- ], ['_', '__'], $identifier);
- return $identifier;
- }
- /**
- * Sets if this request is an Ajax request.
- *
- * @param bool $is_ajax
- * TRUE if this request is an Ajax request, FALSE otherwise.
- */
- public static function setIsAjax($is_ajax) {
- static::$isAjax = $is_ajax;
- }
- /**
- * Prepares a string for use as a valid HTML ID and guarantees uniqueness.
- *
- * This function ensures that each passed HTML ID value only exists once on
- * the page. By tracking the already returned ids, this function enables
- * forms, blocks, and other content to be output multiple times on the same
- * page, without breaking (X)HTML validation.
- *
- * For already existing IDs, a counter is appended to the ID string.
- * Therefore, JavaScript and CSS code should not rely on any value that was
- * generated by this function and instead should rely on manually added CSS
- * classes or similarly reliable constructs.
- *
- * Two consecutive hyphens separate the counter from the original ID. To
- * manage uniqueness across multiple Ajax requests on the same page, Ajax
- * requests POST an array of all IDs currently present on the page, which are
- * used to prime this function's cache upon first invocation.
- *
- * To allow reverse-parsing of IDs submitted via Ajax, any multiple
- * consecutive hyphens in the originally passed $id are replaced with a
- * single hyphen.
- *
- * @param string $id
- * The ID to clean.
- *
- * @return string
- * The cleaned ID.
- */
- public static function getUniqueId($id) {
- // If this is an Ajax request, then content returned by this page request
- // will be merged with content already on the base page. The HTML IDs must
- // be unique for the fully merged content. Therefore use unique IDs.
- if (static::$isAjax) {
- return static::getId($id) . '--' . Crypt::randomBytesBase64(8);
- }
- // @todo Remove all that code once we switch over to random IDs only,
- // see https://www.drupal.org/node/1090592.
- if (!isset(static::$seenIdsInit)) {
- static::$seenIdsInit = [];
- }
- if (!isset(static::$seenIds)) {
- static::$seenIds = static::$seenIdsInit;
- }
- $id = static::getId($id);
- // Ensure IDs are unique by appending a counter after the first occurrence.
- // The counter needs to be appended with a delimiter that does not exist in
- // the base ID. Requiring a unique delimiter helps ensure that we really do
- // return unique IDs and also helps us re-create the $seen_ids array during
- // Ajax requests.
- if (isset(static::$seenIds[$id])) {
- $id = $id . '--' . ++static::$seenIds[$id];
- }
- else {
- static::$seenIds[$id] = 1;
- }
- return $id;
- }
- /**
- * Prepares a string for use as a valid HTML ID.
- *
- * Only use this function when you want to intentionally skip the uniqueness
- * guarantee of self::getUniqueId().
- *
- * @param string $id
- * The ID to clean.
- *
- * @return string
- * The cleaned ID.
- *
- * @see self::getUniqueId()
- */
- public static function getId($id) {
- $id = str_replace([' ', '_', '[', ']'], ['-', '-', '-', ''], mb_strtolower($id));
- // As defined in http://www.w3.org/TR/html4/types.html#type-name, HTML IDs can
- // only contain letters, digits ([0-9]), hyphens ("-"), underscores ("_"),
- // colons (":"), and periods ("."). We strip out any character not in that
- // list. Note that the CSS spec doesn't allow colons or periods in identifiers
- // (http://www.w3.org/TR/CSS21/syndata.html#characters), so we strip those two
- // characters as well.
- $id = preg_replace('/[^A-Za-z0-9\-_]/', '', $id);
- // Removing multiple consecutive hyphens.
- $id = preg_replace('/\-+/', '-', $id);
- return $id;
- }
- /**
- * Resets the list of seen IDs.
- */
- public static function resetSeenIds() {
- static::$seenIds = NULL;
- }
- /**
- * Normalizes an HTML snippet.
- *
- * This function is essentially \DOMDocument::normalizeDocument(), but
- * operates on an HTML string instead of a \DOMDocument.
- *
- * @param string $html
- * The HTML string to normalize.
- *
- * @return string
- * The normalized HTML string.
- */
- public static function normalize($html) {
- $document = static::load($html);
- return static::serialize($document);
- }
- /**
- * Parses an HTML snippet and returns it as a DOM object.
- *
- * This function loads the body part of a partial (X)HTML document and returns
- * a full \DOMDocument object that represents this document.
- *
- * Use \Drupal\Component\Utility\Html::serialize() to serialize this
- * \DOMDocument back to a string.
- *
- * @param string $html
- * The partial (X)HTML snippet to load. Invalid markup will be corrected on
- * import.
- *
- * @return \DOMDocument
- * A \DOMDocument that represents the loaded (X)HTML snippet.
- */
- public static function load($html) {
- $document = <<<EOD
- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
- <html xmlns="http://www.w3.org/1999/xhtml">
- <head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /></head>
- <body>!html</body>
- </html>
- EOD;
- // PHP's \DOMDocument serialization adds extra whitespace when the markup
- // of the wrapping document contains newlines, so ensure we remove all
- // newlines before injecting the actual HTML body to be processed.
- $document = strtr($document, ["\n" => '', '!html' => $html]);
- $dom = new \DOMDocument();
- // Ignore warnings during HTML soup loading.
- @$dom->loadHTML($document);
- return $dom;
- }
- /**
- * Converts the body of a \DOMDocument back to an HTML snippet.
- *
- * The function serializes the body part of a \DOMDocument back to an (X)HTML
- * snippet. The resulting (X)HTML snippet will be properly formatted to be
- * compatible with HTML user agents.
- *
- * @param \DOMDocument $document
- * A \DOMDocument object to serialize, only the tags below the first <body>
- * node will be converted.
- *
- * @return string
- * A valid (X)HTML snippet, as a string.
- */
- public static function serialize(\DOMDocument $document) {
- $body_node = $document->getElementsByTagName('body')->item(0);
- $html = '';
- if ($body_node !== NULL) {
- foreach ($body_node->getElementsByTagName('script') as $node) {
- static::escapeCdataElement($node);
- }
- foreach ($body_node->getElementsByTagName('style') as $node) {
- static::escapeCdataElement($node, '/*', '*/');
- }
- foreach ($body_node->childNodes as $node) {
- $html .= $document->saveXML($node);
- }
- }
- return $html;
- }
- /**
- * Adds comments around a <!CDATA section in a \DOMNode.
- *
- * \DOMDocument::loadHTML() in \Drupal\Component\Utility\Html::load() makes
- * CDATA sections from the contents of inline script and style tags. This can
- * cause HTML4 browsers to throw exceptions.
- *
- * This function attempts to solve the problem by creating a
- * \DOMDocumentFragment to comment the CDATA tag.
- *
- * @param \DOMNode $node
- * The element potentially containing a CDATA node.
- * @param string $comment_start
- * (optional) A string to use as a comment start marker to escape the CDATA
- * declaration. Defaults to '//'.
- * @param string $comment_end
- * (optional) A string to use as a comment end marker to escape the CDATA
- * declaration. Defaults to an empty string.
- */
- public static function escapeCdataElement(\DOMNode $node, $comment_start = '//', $comment_end = '') {
- foreach ($node->childNodes as $child_node) {
- if ($child_node instanceof \DOMCdataSection) {
- $embed_prefix = "\n<!--{$comment_start}--><![CDATA[{$comment_start} ><!--{$comment_end}\n";
- $embed_suffix = "\n{$comment_start}--><!]]>{$comment_end}\n";
- // Prevent invalid cdata escaping as this would throw a DOM error.
- // This is the same behavior as found in libxml2.
- // Related W3C standard: http://www.w3.org/TR/REC-xml/#dt-cdsection
- // Fix explanation: http://wikipedia.org/wiki/CDATA#Nesting
- $data = str_replace(']]>', ']]]]><![CDATA[>', $child_node->data);
- $fragment = $node->ownerDocument->createDocumentFragment();
- $fragment->appendXML($embed_prefix . $data . $embed_suffix);
- $node->appendChild($fragment);
- $node->removeChild($child_node);
- }
- }
- }
- /**
- * Decodes all HTML entities including numerical ones to regular UTF-8 bytes.
- *
- * Double-escaped entities will only be decoded once ("&lt;" becomes
- * "<", not "<"). Be careful when using this function, as it will revert
- * previous sanitization efforts (<script> will become <script>).
- *
- * This method is not the opposite of Html::escape(). For example, this method
- * will convert "é" to "é", whereas Html::escape() will not convert "é"
- * to "é".
- *
- * @param string $text
- * The text to decode entities in.
- *
- * @return string
- * The input $text, with all HTML entities decoded once.
- *
- * @see html_entity_decode()
- * @see \Drupal\Component\Utility\Html::escape()
- */
- public static function decodeEntities($text) {
- return html_entity_decode($text, ENT_QUOTES, 'UTF-8');
- }
- /**
- * Escapes text by converting special characters to HTML entities.
- *
- * This method escapes HTML for sanitization purposes by replacing the
- * following special characters with their HTML entity equivalents:
- * - & (ampersand) becomes &
- * - " (double quote) becomes "
- * - ' (single quote) becomes '
- * - < (less than) becomes <
- * - > (greater than) becomes >
- * Special characters that have already been escaped will be double-escaped
- * (for example, "<" becomes "&lt;"), and invalid UTF-8 encoding
- * will be converted to the Unicode replacement character ("�").
- *
- * This method is not the opposite of Html::decodeEntities(). For example,
- * this method will not encode "é" to "é", whereas
- * Html::decodeEntities() will convert all HTML entities to UTF-8 bytes,
- * including "é" and "<" to "é" and "<".
- *
- * When constructing @link theme_render render arrays @endlink passing the output of Html::escape() to
- * '#markup' is not recommended. Use the '#plain_text' key instead and the
- * renderer will autoescape the text.
- *
- * @param string $text
- * The input text.
- *
- * @return string
- * The text with all HTML special characters converted.
- *
- * @see htmlspecialchars()
- * @see \Drupal\Component\Utility\Html::decodeEntities()
- *
- * @ingroup sanitization
- */
- public static function escape($text) {
- return htmlspecialchars($text, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
- }
- /**
- * Converts all root-relative URLs to absolute URLs.
- *
- * Does not change any existing protocol-relative or absolute URLs. Does not
- * change other relative URLs because they would result in different absolute
- * URLs depending on the current path. For example: when the same content
- * containing such a relative URL (for example 'image.png'), is served from
- * its canonical URL (for example 'http://example.com/some-article') or from
- * a listing or feed (for example 'http://example.com/all-articles') their
- * "current path" differs, resulting in different absolute URLs:
- * 'http://example.com/some-article/image.png' versus
- * 'http://example.com/all-articles/image.png'. Only one can be correct.
- * Therefore relative URLs that are not root-relative cannot be safely
- * transformed and should generally be avoided.
- *
- * Necessary for HTML that is served outside of a website, for example, RSS
- * and e-mail.
- *
- * @param string $html
- * The partial (X)HTML snippet to load. Invalid markup will be corrected on
- * import.
- * @param string $scheme_and_host
- * The root URL, which has a URI scheme, host and optional port.
- *
- * @return string
- * The updated (X)HTML snippet.
- */
- public static function transformRootRelativeUrlsToAbsolute($html, $scheme_and_host) {
- assert(empty(array_diff(array_keys(parse_url($scheme_and_host)), ["scheme", "host", "port"])), '$scheme_and_host contains scheme, host and port at most.');
- assert(isset(parse_url($scheme_and_host)["scheme"]), '$scheme_and_host is absolute and hence has a scheme.');
- assert(isset(parse_url($scheme_and_host)["host"]), '$base_url is absolute and hence has a host.');
- $html_dom = Html::load($html);
- $xpath = new \DOMXpath($html_dom);
- // Update all root-relative URLs to absolute URLs in the given HTML.
- foreach (static::$uriAttributes as $attr) {
- foreach ($xpath->query("//*[starts-with(@$attr, '/') and not(starts-with(@$attr, '//'))]") as $node) {
- $node->setAttribute($attr, $scheme_and_host . $node->getAttribute($attr));
- }
- foreach ($xpath->query("//*[@srcset]") as $node) {
- // @see https://html.spec.whatwg.org/multipage/embedded-content.html#attr-img-srcset
- // @see https://html.spec.whatwg.org/multipage/embedded-content.html#image-candidate-string
- $image_candidate_strings = explode(',', $node->getAttribute('srcset'));
- $image_candidate_strings = array_map('trim', $image_candidate_strings);
- for ($i = 0; $i < count($image_candidate_strings); $i++) {
- $image_candidate_string = $image_candidate_strings[$i];
- if ($image_candidate_string[0] === '/' && $image_candidate_string[1] !== '/') {
- $image_candidate_strings[$i] = $scheme_and_host . $image_candidate_string;
- }
- }
- $node->setAttribute('srcset', implode(', ', $image_candidate_strings));
- }
- }
- return Html::serialize($html_dom);
- }
- }
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