<?php

/**
 * Validates an IPv6 address.
 * @author Feyd @ forums.devnetwork.net (public domain)
 * @note This function requires brackets to have been removed from address
 *       in URI.
 */
class HTMLPurifier_AttrDef_URI_IPv6 extends HTMLPurifier_AttrDef_URI_IPv4
{
    
    public function validate($aIP, $config, $context) {
        
        if (!$this->ip4) $this->_loadRegex();
        
        $original = $aIP;
        
        $hex = '[0-9a-fA-F]';
        $blk = '(?:' . $hex . '{1,4})';
        $pre = '(?:/(?:12[0-8]|1[0-1][0-9]|[1-9][0-9]|[0-9]))';   // /0 - /128
        
        //      prefix check
        if (strpos($aIP, '/') !== false)
        {
                if (preg_match('#' . $pre . '$#s', $aIP, $find))
                {
                        $aIP = substr($aIP, 0, 0-strlen($find[0]));
                        unset($find);
                }
                else
                {
                        return false;
                }
        }
        
        //      IPv4-compatiblity check       
        if (preg_match('#(?<=:'.')' . $this->ip4 . '$#s', $aIP, $find))
        {
                $aIP = substr($aIP, 0, 0-strlen($find[0]));
                $ip = explode('.', $find[0]);
                $ip = array_map('dechex', $ip);
                $aIP .= $ip[0] . $ip[1] . ':' . $ip[2] . $ip[3];
                unset($find, $ip);
        }
        
        //      compression check
        $aIP = explode('::', $aIP);
        $c = count($aIP);
        if ($c > 2)
        {
                return false;
        }
        elseif ($c == 2)
        {
                list($first, $second) = $aIP;
                $first = explode(':', $first);
                $second = explode(':', $second);
               
                if (count($first) + count($second) > 8)
                {
                        return false;
                }
               
                while(count($first) < 8)
                {
                        array_push($first, '0');
                }

                array_splice($first, 8 - count($second), 8, $second);
                $aIP = $first;
                unset($first,$second);
        }
        else
        {
                $aIP = explode(':', $aIP[0]);
        }
        $c = count($aIP);
        
        if ($c != 8)
        {
                return false;
        }
       
        //      All the pieces should be 16-bit hex strings. Are they?
        foreach ($aIP as $piece)
        {
                if (!preg_match('#^[0-9a-fA-F]{4}$#s', sprintf('%04s', $piece)))
                {
                        return false;
                }
        }
        
        return $original;
        
    }
    
}

