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1 efrain 1
<?php
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/**
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 * Validates a host according to the IPv4, IPv6 and DNS (future) specifications.
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 */
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class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
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{
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    /**
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     * IPv4 sub-validator.
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     * @type HTMLPurifier_AttrDef_URI_IPv4
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     */
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    protected $ipv4;
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    /**
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     * IPv6 sub-validator.
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     * @type HTMLPurifier_AttrDef_URI_IPv6
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     */
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    protected $ipv6;
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    public function __construct()
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    {
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        $this->ipv4 = new HTMLPurifier_AttrDef_URI_IPv4();
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        $this->ipv6 = new HTMLPurifier_AttrDef_URI_IPv6();
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    }
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    /**
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     * @param string $string
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     * @param HTMLPurifier_Config $config
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     * @param HTMLPurifier_Context $context
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     * @return bool|string
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     */
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    public function validate($string, $config, $context)
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    {
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        $length = strlen($string);
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        // empty hostname is OK; it's usually semantically equivalent:
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        // the default host as defined by a URI scheme is used:
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        //
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        //      If the URI scheme defines a default for host, then that
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        //      default applies when the host subcomponent is undefined
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        //      or when the registered name is empty (zero length).
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        if ($string === '') {
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            return '';
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        }
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        if ($length > 1 && $string[0] === '[' && $string[$length - 1] === ']') {
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            //IPv6
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            $ip = substr($string, 1, $length - 2);
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            $valid = $this->ipv6->validate($ip, $config, $context);
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            if ($valid === false) {
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                return false;
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            }
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            return '[' . $valid . ']';
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        }
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        // need to do checks on unusual encodings too
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        $ipv4 = $this->ipv4->validate($string, $config, $context);
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        if ($ipv4 !== false) {
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            return $ipv4;
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        }
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        // A regular domain name.
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        // This doesn't match I18N domain names, but we don't have proper IRI support,
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        // so force users to insert Punycode.
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1441 ariadna 66
        // Underscores defined as Unreserved Characters in RFC 3986 are
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        // allowed in a URI. There are cases where we want to consider a
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        // URI containing "_" such as "_dmarc.example.com".
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        // Underscores are not allowed in the default. If you want to
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        // allow it, set Core.AllowHostnameUnderscore to true.
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        $underscore = $config->get('Core.AllowHostnameUnderscore') ? '_' : '';
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        // Based off of RFC 1738, but amended so that
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        // as per RFC 3696, the top label need only not be all numeric.
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        // The productions describing this are:
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        $a   = '[a-z]';     // alpha
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        $an  = "[a-z0-9$underscore]";  // alphanum
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        $and = "[a-z0-9-$underscore]"; // alphanum | "-"
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        // domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
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        $domainlabel = "$an(?:$and*$an)?";
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        // AMENDED as per RFC 3696
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        // toplabel    = alphanum | alphanum *( alphanum | "-" ) alphanum
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        //      side condition: not all numeric
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        $toplabel = "$an(?:$and*$an)?";
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        // hostname    = *( domainlabel "." ) toplabel [ "." ]
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        if (preg_match("/^(?:$domainlabel\.)*($toplabel)\.?$/i", $string, $matches)) {
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            if (!ctype_digit($matches[1])) {
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                return $string;
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            }
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        }
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        // PHP 5.3 and later support this functionality natively
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        if (function_exists('idn_to_ascii')) {
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            if (defined('IDNA_NONTRANSITIONAL_TO_ASCII') && defined('INTL_IDNA_VARIANT_UTS46')) {
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                $string = idn_to_ascii($string, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46);
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            } else {
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                $string = idn_to_ascii($string);
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            }
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        // If we have Net_IDNA2 support, we can support IRIs by
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        // punycoding them. (This is the most portable thing to do,
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        // since otherwise we have to assume browsers support
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        } elseif ($config->get('Core.EnableIDNA') && class_exists('Net_IDNA2')) {
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            $idna = new Net_IDNA2(array('encoding' => 'utf8', 'overlong' => false, 'strict' => true));
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            // we need to encode each period separately
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            $parts = explode('.', $string);
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            try {
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                $new_parts = array();
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                foreach ($parts as $part) {
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                    $encodable = false;
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                    for ($i = 0, $c = strlen($part); $i < $c; $i++) {
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                        if (ord($part[$i]) > 0x7a) {
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                            $encodable = true;
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                            break;
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                        }
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                    }
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                    if (!$encodable) {
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                        $new_parts[] = $part;
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                    } else {
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                        $new_parts[] = $idna->encode($part);
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                    }
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                }
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                $string = implode('.', $new_parts);
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            } catch (Exception $e) {
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                // XXX error reporting
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            }
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        }
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        // Try again
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        if (preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string)) {
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            return $string;
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        }
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        return false;
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    }
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}
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// vim: et sw=4 sts=4