.Net C#域账号登陆验证

//获取登陆页输入的域账号、密码
string domainIP = "";　　　　　　//域IP
string userAccount = "";　　　　//域账号
string Password = "";　　　　　　//域账号密码 　　　　　　　　　
using DirectoryEntry deUser = new DirectoryEntry@"LDAP://" + domainIP, userAccount, Password))
{
DirectorySearcher src = new DirectorySearcherdeUser);
src.Filter = "&&objectCategory=person)objectClass=user))sAMAccountName=" + userAccount + "))";
src.PropertiesToLoad.Add"cn");
src.SearchRoot = deUser;
src.SearchScope = SearchScope.Subtree;

SearchResult result = src.FindOne);
if result != null)//验证成功
{
DirectoryEntry de = result.GetDirectoryEntry);
string userID = de.Username;
#region 域账号验证通过后判断是否用户在本系统中
var existUser = new DAL.Maintain.UserOP).GetDatauserID);
if existUser == null)
{
ViewBag.ErrorInfo = "提示：您未开通系统的权限，请联系管理员。<br/>You have no access to the system, please contact the administrator!";
return View);
} 
#endregion

FormsAuthentication.SetAuthCookieuserID, false);
Session.Add"UserID", userID);
Logger.DefaultLog.Info"登陆sessionUserID:" + Session["UserID"].ToString));

if string.IsNullOrEmptyReturnUrl))
{
return RedirectUrl.Action"Index", "Home"));
}
else
{
//...
}
}
else
{
ViewBag.ErrorInfo = "提示：登录失败: 未知的用户名或错误密码。<br/>Account or Password is incorrect!";
return View);
}

}