library/HTMLPurifier/AttrDef/URI/Host.php

   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             $string = idn_to_ascii($string, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46);
 101
 102         // If we have Net_IDNA2 support, we can support IRIs by
 103         // punycoding them. (This is the most portable thing to do,
 104         // since otherwise we have to assume browsers support
 105         } elseif ($config->get('Core.EnableIDNA')) {
 106             $idna = new Net_IDNA2(array('encoding' => 'utf8', 'overlong' => false, 'strict' => true));
 107             // we need to encode each period separately
 108             $parts = explode('.', $string);
 109             try {
 110                 $new_parts = array();
 111                 foreach ($parts as $part) {
 112                     $encodable = false;
 113                     for ($i = 0, $c = strlen($part); $i < $c; $i++) {
 114                         if (ord($part[$i]) > 0x7a) {
 115                             $encodable = true;
 116                             break;
 117                         }
 118                     }
 119                     if (!$encodable) {
 120                         $new_parts[] = $part;
 121                     } else {
 122                         $new_parts[] = $idna->encode($part);
 123                     }
 124                 }
 125                 $string = implode('.', $new_parts);
 126             } catch (Exception $e) {
 127                 // XXX error reporting
 128             }
 129         }
 130         // Try again
 131         if (preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string)) {
 132             return $string;
 133         }
 134         return false;
 135     }
 136 }
 137
 138 // vim: et sw=4 sts=4