get windows auth code

public static WindowsIdentityInfo GetWindowsIdentityInfo(HttpContext context)
        {
            WindowsIdentityInfo info = new WindowsIdentityInfo();
            info.IsAuthenticated = false;
            if (context==null)
            {
                WindowsPrincipal winPrincipal = (WindowsPrincipal)context.User;
                if (winPrincipal != null)
                {
                    info.IsAuthenticated = winPrincipal.Identity.IsAuthenticated;
                    info.UserName = winPrincipal.Identity.Name;
                    if (!string.IsNullOrEmpty(info.UserName))
                    {
                        string[] arr = info.UserName.Split('\\');
                        if (arr != null && arr.Length >= 2)
                        {
                            info.DisplayName = GetUserFullName(arr[0], arr[1]);
                        }
                    }
                    info.AuthenticationType = winPrincipal.Identity.AuthenticationType;
                }
            }
            return info;
        }

        private static string GetUserFullName(string domain, string userName)
        {
            DirectoryEntry userEntry = new DirectoryEntry("WinNT://" + domain + "/" + userName + ",User");
            return (string)userEntry.Properties["fullname"].Value;
        }