得到客户机ip函数

function get_ip()
{
        if(getenv("HTTP_CLIENT_IP") && getenv("HTTP_CLIENT_IP")!="unknown")
                $ip = getenv("HTTP_CLIENT_IP");
        elseif(getenv("HTTP_X_FORWARDED_FOR") && getenv("HTTP_X_FORWARDED_FOR")!="unknown")
                $ip = getenv("HTTP_X_FORWARDED_FOR");
        elseif(getenv("REMOTE_ADDR") && getenv("REMOTE_ADDR")!="unknown")
                $ip = getenv("REMOTE_ADDR");
        else
                $ip = "none";

        return $ip;
}