File indexing completed on 2025-01-26 05:29:06

 <?php
 
 /**
  * Validates a host according to the IPv4, IPv6 and DNS (future) specifications.
  */
 class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
 {
 
     /**
      * IPv4 sub-validator.
      * @type HTMLPurifier_AttrDef_URI_IPv4
      */
     protected $ipv4;
 
     /**
      * IPv6 sub-validator.
      * @type HTMLPurifier_AttrDef_URI_IPv6
      */
     protected $ipv6;
 
     public function __construct()
     {
         $this->ipv4 = new HTMLPurifier_AttrDef_URI_IPv4();
         $this->ipv6 = new HTMLPurifier_AttrDef_URI_IPv6();
     }
 
     /**
      * @param string $string
      * @param HTMLPurifier_Config $config
      * @param HTMLPurifier_Context $context
      * @return bool|string
      */
     public function validate($string, $config, $context)
     {
         $length = strlen($string);
         // empty hostname is OK; it's usually semantically equivalent:
         // the default host as defined by a URI scheme is used:
         //
         //      If the URI scheme defines a default for host, then that
         //      default applies when the host subcomponent is undefined
         //      or when the registered name is empty (zero length).
         if ($string === '') {
             return '';
         }
         if ($length > 1 && $string[0] === '[' && $string[$length - 1] === ']') {
             //IPv6
             $ip = substr($string, 1, $length - 2);
             $valid = $this->ipv6->validate($ip, $config, $context);
             if ($valid === false) {
                 return false;
             }
             return '[' . $valid . ']';
         }
 
         // need to do checks on unusual encodings too
         $ipv4 = $this->ipv4->validate($string, $config, $context);
         if ($ipv4 !== false) {
             return $ipv4;
         }
 
         // A regular domain name.
 
         // This doesn't match I18N domain names, but we don't have proper IRI support,
         // so force users to insert Punycode.
 
         // There is not a good sense in which underscores should be
         // allowed, since it's technically not! (And if you go as
         // far to allow everything as specified by the DNS spec...
         // well, that's literally everything, modulo some space limits
         // for the components and the overall name (which, by the way,
         // we are NOT checking!).  So we (arbitrarily) decide this:
         // let's allow underscores wherever we would have allowed
         // hyphens, if they are enabled.  This is a pretty good match
         // for browser behavior, for example, a large number of browsers
         // cannot handle foo_.example.com, but foo_bar.example.com is
         // fairly well supported.
         $underscore = $config->get('Core.AllowHostnameUnderscore') ? '_' : '';
 
         // Based off of RFC 1738, but amended so that
         // as per RFC 3696, the top label need only not be all numeric.
         // The productions describing this are:
         $a   = '[a-z]';     // alpha
         $an  = '[a-z0-9]';  // alphanum
         $and = "[a-z0-9-$underscore]"; // alphanum | "-"
         // domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
         $domainlabel = "$an(?:$and*$an)?";
         // AMENDED as per RFC 3696
         // toplabel    = alphanum | alphanum *( alphanum | "-" ) alphanum
         //      side condition: not all numeric
         $toplabel = "$an(?:$and*$an)?";
         // hostname    = *( domainlabel "." ) toplabel [ "." ]
         if (preg_match("/^(?:$domainlabel\.)*($toplabel)\.?$/i", $string, $matches)) {
             if (!ctype_digit($matches[1])) {
                 return $string;
             }
         }
 
         // PHP 5.3 and later support this functionality natively
         if (function_exists('idn_to_ascii')) {
             $string = idn_to_ascii($string);
 
         // If we have Net_IDNA2 support, we can support IRIs by
         // punycoding them. (This is the most portable thing to do,
         // since otherwise we have to assume browsers support
         } elseif ($config->get('Core.EnableIDNA')) {
             $idna = new Net_IDNA2(array('encoding' => 'utf8', 'overlong' => false, 'strict' => true));
             // we need to encode each period separately
             $parts = explode('.', $string);
             try {
                 $new_parts = array();
                 foreach ($parts as $part) {
                     $encodable = false;
                     for ($i = 0, $c = strlen($part); $i < $c; $i++) {
                         if (ord($part[$i]) > 0x7a) {
                             $encodable = true;
                             break;
                         }
                     }
                     if (!$encodable) {
                         $new_parts[] = $part;
                     } else {
                         $new_parts[] = $idna->encode($part);
                     }
                 }
                 $string = implode('.', $new_parts);
             } catch (Exception $e) {
                 // XXX error reporting
             }
         }
         // Try again
         if (preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string)) {
             return $string;
         }
         return false;
     }
 }
 
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