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<?php |
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/** |
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* @package s9e\TextFormatter |
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* @copyright Copyright (c) 2010-2017 The s9e Authors |
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* @license http://www.opensource.org/licenses/mit-license.php The MIT License |
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*/ |
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namespace s9e\TextFormatter\Parser\AttributeFilters; |
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use s9e\TextFormatter\Parser\Logger; |
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class UrlFilter |
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{ |
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/** |
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* Filter a URL |
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* |
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* @param mixed $attrValue Original URL |
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* @param array $urlConfig URL config |
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* @param Logger $logger Parser's logger |
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* @return mixed Cleaned up URL if valid, FALSE otherwise |
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*/ |
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public static function filter($attrValue, array $urlConfig, Logger $logger = null) |
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{ |
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/** |
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* Trim the URL to conform with HTML5 then parse it |
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* @link http://dev.w3.org/html5/spec/links.html#attr-hyperlink-href |
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*/ |
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$p = self::parseUrl(trim($attrValue)); |
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$error = self::validateUrl($urlConfig, $p); |
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if (!empty($error)) |
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{ |
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if (isset($logger)) |
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{ |
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$p['attrValue'] = $attrValue; |
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$logger->err($error, $p); |
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} |
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return false; |
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} |
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return self::rebuildUrl($p); |
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} |
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/** |
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* Parse a URL and return its components |
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* |
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* Similar to PHP's own parse_url() except that all parts are always returned |
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* |
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* @param string $url Original URL |
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* @return array |
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*/ |
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protected static function parseUrl($url) |
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{ |
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$regexp = '(^(?:([a-z][-+.\\w]*):)?(?://(?:([^:/?#]*)(?::([^/?#]*)?)?@)?(?:(\\[[a-f\\d:]+\\]|[^:/?#]+)(?::(\\d*))?)?(?![^/?#]))?([^?#]*)(\\?[^#]*)?(#.*)?$)Di'; |
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// NOTE: this regexp always matches because of the last three captures |
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preg_match($regexp, $url, $m); |
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$parts = []; |
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$tokens = ['scheme', 'user', 'pass', 'host', 'port', 'path', 'query', 'fragment']; |
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foreach ($tokens as $i => $name) |
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{ |
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$parts[$name] = (isset($m[$i + 1])) ? $m[$i + 1] : ''; |
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} |
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/** |
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* @link http://tools.ietf.org/html/rfc3986#section-3.1 |
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* |
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* 'An implementation should accept uppercase letters as equivalent to lowercase in |
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* scheme names (e.g., allow "HTTP" as well as "http") for the sake of robustness but |
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* should only produce lowercase scheme names for consistency.' |
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*/ |
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$parts['scheme'] = strtolower($parts['scheme']); |
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/** |
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* Normalize the domain label separators and remove trailing dots |
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* @link http://url.spec.whatwg.org/#domain-label-separators |
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*/ |
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$parts['host'] = rtrim(preg_replace("/\xE3\x80\x82|\xEF(?:\xBC\x8E|\xBD\xA1)/s", '.', $parts['host']), '.'); |
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// Test whether host has non-ASCII characters and punycode it if possible |
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if (preg_match('#[^[:ascii:]]#', $parts['host']) && function_exists('idn_to_ascii')) |
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{ |
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$variant = (defined('INTL_IDNA_VARIANT_UTS46')) ? INTL_IDNA_VARIANT_UTS46 : 0; |
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$parts['host'] = idn_to_ascii($parts['host'], 0, $variant); |
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} |
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return $parts; |
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} |
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/** |
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* Rebuild a parsed URL |
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* |
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* @param array $p Parsed URL |
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* @return string |
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*/ |
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protected static function rebuildUrl(array $p) |
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{ |
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$url = ''; |
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if ($p['scheme'] !== '') |
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{ |
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$url .= $p['scheme'] . ':'; |
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} |
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if ($p['host'] === '') |
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{ |
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// Allow the file: scheme to not have a host and ensure it starts with slashes |
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if ($p['scheme'] === 'file') |
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{ |
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$url .= '//'; |
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} |
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} |
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else |
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{ |
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$url .= '//'; |
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// Add the credentials if applicable |
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if ($p['user'] !== '') |
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{ |
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// Reencode the credentials in case there are invalid chars in them, or suspicious |
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// characters such as : or @ that could confuse a browser into connecting to the |
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// wrong host (or at least, to a host that is different than the one we thought) |
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$url .= rawurlencode(urldecode($p['user'])); |
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if ($p['pass'] !== '') |
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{ |
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$url .= ':' . rawurlencode(urldecode($p['pass'])); |
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} |
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$url .= '@'; |
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} |
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$url .= $p['host']; |
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// Append the port number (note that as per the regexp it can only contain digits) |
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if ($p['port'] !== '') |
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{ |
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$url .= ':' . $p['port']; |
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} |
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} |
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// Build the path, including the query and fragment parts |
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$path = $p['path'] . $p['query'] . $p['fragment']; |
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/** |
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* "For consistency, URI producers and normalizers should use uppercase hexadecimal digits |
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* for all percent- encodings." |
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* |
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* @link http://tools.ietf.org/html/rfc3986#section-2.1 |
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*/ |
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$path = preg_replace_callback( |
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'/%.?[a-f]/', |
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function ($m) |
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{ |
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return strtoupper($m[0]); |
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}, |
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$path |
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); |
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// Append the sanitized path to the URL |
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$url .= self::sanitizeUrl($path); |
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// Replace the first colon if there's no scheme and it could potentially be interpreted as |
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// the scheme separator |
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if (!$p['scheme']) |
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{ |
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$url = preg_replace('#^([^/]*):#', '$1%3A', $url); |
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} |
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return $url; |
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} |
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/** |
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* Sanitize a URL for safe use regardless of context |
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* |
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* This method URL-encodes some sensitive characters in case someone would want to use the URL in |
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* some JavaScript thingy, or in CSS. We also encode characters that are not allowed in the path |
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* of a URL as defined in RFC 3986 appendix A, including percent signs that are not immediately |
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* followed by two hex digits. |
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* |
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* " and ' to prevent breaking out of quotes (JavaScript or otherwise) |
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* ( and ) to prevent the use of functions in JavaScript (eval()) or CSS (expression()) |
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* < and > to prevent breaking out of <script> |
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* \r and \n because they're illegal in JavaScript |
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* [ and ] because the W3 validator rejects them and they "should" be escaped as per RFC 3986 |
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* Non-ASCII characters as per RFC 3986 |
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* Control codes and spaces, as per RFC 3986 |
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* |
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* @link http://sla.ckers.org/forum/read.php?2,51478 |
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* @link http://timelessrepo.com/json-isnt-a-javascript-subset |
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* @link http://www.ietf.org/rfc/rfc3986.txt |
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* @link http://stackoverflow.com/a/1547922 |
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* @link http://tools.ietf.org/html/rfc3986#appendix-A |
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* |
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* @param string $url Original URL |
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* @return string Sanitized URL |
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*/ |
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public static function sanitizeUrl($url) |
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{ |
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return preg_replace_callback( |
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'/%(?![0-9A-Fa-f]{2})|[^!#-&*-;=?-Z_a-z]/S', |
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function ($m) |
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{ |
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return rawurlencode($m[0]); |
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}, |
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$url |
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); |
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} |
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/** |
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* Validate a parsed URL |
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* |
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* @param array $urlConfig URL config |
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* @param array $p Parsed URL |
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* @return string|null Error message if invalid, or NULL |
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*/ |
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protected static function validateUrl(array $urlConfig, array $p) |
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{ |
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if ($p['scheme'] !== '' && !preg_match($urlConfig['allowedSchemes'], $p['scheme'])) |
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{ |
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return 'URL scheme is not allowed'; |
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} |
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if ($p['host'] === '') |
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{ |
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// Reject malformed URLs such as http:///example.org but allow schemeless paths |
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if ($p['scheme'] !== 'file' && $p['scheme'] !== '') |
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{ |
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return 'Missing host'; |
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} |
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} |
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else |
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{ |
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/** |
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* Test whether the host is valid |
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* @link http://tools.ietf.org/html/rfc1035#section-2.3.1 |
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* @link http://tools.ietf.org/html/rfc1123#section-2 |
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*/ |
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$regexp = '/^(?!-)[-a-z0-9]{0,62}[a-z0-9](?:\\.(?!-)[-a-z0-9]{0,62}[a-z0-9])*$/i'; |
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if (!preg_match($regexp, $p['host'])) |
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{ |
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// If the host invalid, retest as an IPv4 and IPv6 address (IPv6 in brackets) |
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if (!NetworkFilter::filterIpv4($p['host']) |
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&& !NetworkFilter::filterIpv6(preg_replace('/^\\[(.*)\\]$/', '$1', $p['host']))) |
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{ |
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return 'URL host is invalid'; |
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} |
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} |
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if ((isset($urlConfig['disallowedHosts']) && preg_match($urlConfig['disallowedHosts'], $p['host'])) |
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|| (isset($urlConfig['restrictedHosts']) && !preg_match($urlConfig['restrictedHosts'], $p['host']))) |
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{ |
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return 'URL host is not allowed'; |
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} |
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} |
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} |
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} |
s9e /
TextFormatter
