if (req.http.Cookie ~ "(?:^|;\s*)SESS[0-9a-f]+=[^;]{8,}")
{
        cookie.parse(req.http.Cookie);
        cookie.filter_except(regsub(req.http.Cookie, "(?:^|.*;\s*)(SESS[0-9a-f]+)=[^;]{8,}.*", "\1"));
        set req.http.Cookie = cookie.get_string();
}
else
{
        unset req.http.Cookie;
}