php获取客户端公网ip代码

<?php
/*如果是本地服务器获取客户端的ip地址是 127.0.0.1
如果是域名服务器获取客户端的是公网ip地址*/
function get_client_ip() 
 {
      $ipaddress = '';
      if (getenv('HTTP_CLIENT_IP'))
          $ipaddress = getenv('HTTP_CLIENT_IP');
      else if(getenv('HTTP_X_FORWARDED_FOR'))
          $ipaddress = getenv('HTTP_X_FORWARDED_FOR');
      else if(getenv('HTTP_X_FORWARDED'))
          $ipaddress = getenv('HTTP_X_FORWARDED');
      else if(getenv('HTTP_FORWARDED_FOR'))
          $ipaddress = getenv('HTTP_FORWARDED_FOR');
      else if(getenv('HTTP_FORWARDED'))
          $ipaddress = getenv('HTTP_FORWARDED');
      else if(getenv('REMOTE_ADDR'))
          $ipaddress = getenv('REMOTE_ADDR');
      else
          $ipaddress = 'UNKNOWN';

      return $ipaddress; 
 }
echo get_client_ip();
?>