Global.asax handle Application_AuthenticateRequest

protected void Application_AuthenticateRequest(Object sender, EventArgs e)
{
    if (HttpContext.Current.User == null) return;
    if (!HttpContext.Current.User.Identity.IsAuthenticated) return;
    var id = HttpContext.Current.User.Identity as FormsIdentity;
    if (id == null) return;

    FormsAuthenticationTicket ticket = id.Ticket;
    string userData = ticket.UserData;
    string[] roles = userData.Split(',');
    HttpContext.Current.User = new GenericPrincipal(id, roles);
}