Retreive 'real' IP of remote clients

real-ip.php

/**
 * @function _getRealIPv4
 * @abstract Try all methods of obtaining 'real' IP address
 */
function _getRealIPv4()
{
 return (getenv('HTTP_CLIENT_IP') && $this->_ip(getenv('HTTP_CLIENT_IP'))) ?
          getenv('HTTP_CLIENT_IP') :
           (getenv('HTTP_X_FORWARDED_FOR') && $this->_forwarded(getenv('HTTP_X_FORWARDED_FOR'))) ?
            $this->_forwarded(getenv('HTTP_X_FORWARDED_FOR')) :
             (getenv('HTTP_X_FORWARDED') && $this->_ip(getenv('HTTP_X_FORWARDED'))) ?
               getenv('HTTP_X_FORWARDED') :
                (getenv('HTTP_X_FORWARDED_HOST') && $this->_ip(getenv('HTTP_FORWARDED_HOST'))) ?
                  getenv('HTTP_X_FORWARDED_HOST') :
                   (getenv('HTTP_X_FORWARDED_SERVER') && $this->_ip(getenv('HTTP_X_FORWARDED_SERVER'))) ?
                     getenv('HTTP_X_FORWARDED_SERVER') :
                      (getenv('HTTP_X_CLUSTER_CLIENT_IP') && $this->_ip(getenv('HTTP_X_CLIUSTER_CLIENT_IP'))) ?
                        getenv('HTTP_X_CLUSTER_CLIENT_IP') :
                         getenv('REMOTE_ADDR');
}

/**
 * @function _ip
 * @abstract Attempts to determine if IP is non-routeable
 */
function _ip($ip)
{
 if (!empty($ip) && ip2long($ip)!=-1 && ip2long($ip)!=false){
  $nr = array(array('0.0.0.0','2.255.255.255'),
              array('10.0.0.0','10.255.255.255'),
              array('127.0.0.0','127.255.255.255'),
              array('169.254.0.0','169.254.255.255'),
              array('172.16.0.0','172.31.255.255'),
              array('192.0.2.0','192.0.2.255'),
              array('192.168.0.0','192.168.255.255'),
              array('255.255.255.0','255.255.255.255'));
  foreach($nr as $r){
   $min = ip2long($r[0]);
   $max = ip2long($r[1]);
   if ((ip2long($ip) >= $min) && (ip2long($ip) <= $max)) return false;
  }
  return true;
 } else {
  return false;
 }
}

/**
 * @function _forwarded
 * @abstract A helper for HTTP_X_FORWARDED_FOR, loops over comma
 *           separated list of proxies associated with request
 */
function _forwarded($l)
{
 if (!empty($l)){
  foreach (explode(',', $l) as $i){
   if (_ip(trim($i))) {
    return (!_ip(trim($i))) ? false : $i;
   }
  }
 } else {
  return false;
 }
}