Search moodle.org's
Developer Documentation

  • Bug fixes for general core bugs in 3.11.x will end 14 Nov 2022 (12 months plus 6 months extension).
  • Bug fixes for security issues in 3.11.x will end 13 Nov 2023 (18 months plus 12 months extension).
  • PHP version: minimum PHP 7.3.0 Note: minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is supported too.
  • Differences Between: [Versions 37 and 311] [Versions 38 and 311]

       1  <?php
       2  
       3  /**
    
       4   * Validates a host according to the IPv4, IPv6 and DNS (future) specifications.
    
       5   */
       6  class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
       7  {
       8  
       9      /**
    
      10       * IPv4 sub-validator.
    
      11       * @type HTMLPurifier_AttrDef_URI_IPv4
    
      12       */
      13      protected $ipv4;
      14  
      15      /**
    
      16       * IPv6 sub-validator.
    
      17       * @type HTMLPurifier_AttrDef_URI_IPv6
    
      18       */
      19      protected $ipv6;
      20  
      21      public function __construct()
      22      {
      23          $this->ipv4 = new HTMLPurifier_AttrDef_URI_IPv4();
      24          $this->ipv6 = new HTMLPurifier_AttrDef_URI_IPv6();
      25      }
      26  
      27      /**
    
      28       * @param string $string
    
      29       * @param HTMLPurifier_Config $config
    
      30       * @param HTMLPurifier_Context $context
    
      31       * @return bool|string
    
      32       */
      33      public function validate($string, $config, $context)
      34      {
      35          $length = strlen($string);
      36          // empty hostname is OK; it's usually semantically equivalent:
    
      37          // the default host as defined by a URI scheme is used:
    
      38          //
    
      39          //      If the URI scheme defines a default for host, then that
    
      40          //      default applies when the host subcomponent is undefined
    
      41          //      or when the registered name is empty (zero length).
    
      42          if ($string === '') {
      43              return '';
      44          }
      45          if ($length > 1 && $string[0] === '[' && $string[$length - 1] === ']') {
      46              //IPv6
    
      47              $ip = substr($string, 1, $length - 2);
      48              $valid = $this->ipv6->validate($ip, $config, $context);
      49              if ($valid === false) {
      50                  return false;
      51              }
      52              return '[' . $valid . ']';
      53          }
      54  
      55          // need to do checks on unusual encodings too
    
      56          $ipv4 = $this->ipv4->validate($string, $config, $context);
      57          if ($ipv4 !== false) {
      58              return $ipv4;
      59          }
      60  
      61          // A regular domain name.
    
      62  
      63          // This doesn't match I18N domain names, but we don't have proper IRI support,
    
      64          // so force users to insert Punycode.
    
      65  
      66          // There is not a good sense in which underscores should be
    
      67          // allowed, since it's technically not! (And if you go as
    
      68          // far to allow everything as specified by the DNS spec...
    
      69          // well, that's literally everything, modulo some space limits
    
      70          // for the components and the overall name (which, by the way,
    
      71          // we are NOT checking!).  So we (arbitrarily) decide this:
    
      72          // let's allow underscores wherever we would have allowed
    
      73          // hyphens, if they are enabled.  This is a pretty good match
    
      74          // for browser behavior, for example, a large number of browsers
    
      75          // cannot handle foo_.example.com, but foo_bar.example.com is
    
      76          // fairly well supported.
    
      77          $underscore = $config->get('Core.AllowHostnameUnderscore') ? '_' : '';
      78  
      79          // Based off of RFC 1738, but amended so that
    
      80          // as per RFC 3696, the top label need only not be all numeric.
    
      81          // The productions describing this are:
    
      82          $a   = '[a-z]';     // alpha
    
      83          $an  = '[a-z0-9]';  // alphanum
    
      84          $and = "[a-z0-9-$underscore]"; // alphanum | "-"
    
      85          // domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
    
      86          $domainlabel = "$an(?:$and*$an)?";
      87          // AMENDED as per RFC 3696
    
      88          // toplabel    = alphanum | alphanum *( alphanum | "-" ) alphanum
    
      89          //      side condition: not all numeric
    
      90          $toplabel = "$an(?:$and*$an)?";
      91          // hostname    = *( domainlabel "." ) toplabel [ "." ]
    
      92          if (preg_match("/^(?:$domainlabel\.)*($toplabel)\.?$/i", $string, $matches)) {
      93              if (!ctype_digit($matches[1])) {
      94                  return $string;
      95              }
      96          }
      97  
      98          // PHP 5.3 and later support this functionality natively
    
      99          if (function_exists('idn_to_ascii')) {
     100              if (defined('IDNA_NONTRANSITIONAL_TO_ASCII') && defined('INTL_IDNA_VARIANT_UTS46')) {
     101                  $string = idn_to_ascii($string, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46);
     102              } else {
     103                  $string = idn_to_ascii($string);
     104              }
     105  
     106          // If we have Net_IDNA2 support, we can support IRIs by
    
     107          // punycoding them. (This is the most portable thing to do,
    
     108          // since otherwise we have to assume browsers support
    
     109          } elseif ($config->get('Core.EnableIDNA')) {
     110              $idna = new Net_IDNA2(array('encoding' => 'utf8', 'overlong' => false, 'strict' => true));
     111              // we need to encode each period separately
    
     112              $parts = explode('.', $string);
     113              try {
     114                  $new_parts = array();
     115                  foreach ($parts as $part) {
     116                      $encodable = false;
     117                      for ($i = 0, $c = strlen($part); $i < $c; $i++) {
     118                          if (ord($part[$i]) > 0x7a) {
     119                              $encodable = true;
     120                              break;
     121                          }
     122                      }
     123                      if (!$encodable) {
     124                          $new_parts[] = $part;
     125                      } else {
     126                          $new_parts[] = $idna->encode($part);
     127                      }
     128                  }
     129                  $string = implode('.', $new_parts);
     130              } catch (Exception $e) {
     131                  // XXX error reporting
    
     132              }
     133          }
     134          // Try again
    
     135          if (preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string)) {
     136              return $string;
     137          }
     138          return false;
     139      }
     140  }
     141  
     142  // vim: et sw=4 sts=4