How to set Thread.CurrentPrincipal for use throughout the application?

Question

In an ASP.net application I'm using a Login control with a custom membership provider that I wrote. What I want to do is to set Thread.CurrentPrincipal to my custom Principal object, just after the user is authenticated.

I'm using the setter: Thread.CurrentPrincipal and it sets the Principal object for me but, on all the consequent threads this CurrentPrincipal is overridden with the default one.

Here is my code for the Authenticate event of the Login control:

protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
    {
        string username = Login1.UserName;
        string password = Login1.Password;

        if (Membership.ValidateUser(username, password))
        {
            var login = sender as Login;
            var phoenixIdentity = new PhoenixIdentity("B", "Forms" , true);
            var principal = new PhoenixPrincipal(phoenixIdentity);

            Thread.CurrentPrincipal = principal;
            AppDomain.CurrentDomain.SetThreadPrincipal(principal);

            HttpContext.Current.User = principal;

            e.Authenticated = true;
        }
    }

For example, imagine that I login with the username A, everything goes well... Validation passes, but I hardcode the user with the username B in the Identity object which is set to the Principal object I set as the CurrentPrincipal object.

When I check which user is set to the CurrentPrincipal Identity at the end of this method it says it's user B. But when I load another page and then check what the Identity of the CurrentPrincipal is, it says it's user A.

So, how can I make my CurrentPrincipal object to be persistent across all other threads, and where/when does this Login control set the CurrentPrincipal object of the Thread?

Answer 1

Tadas is not wrong, FormsAuthentication correctly implemented will not cause this problem.

Your page is accessible even without login, only in the login page, your thread's principle is set manually by you, but when you hit the other URL, it sure doesnt call your login page and remember each page runs on its own different thread. If you request first page and set thread principle and you request second page in same browser instance, it may or may not be the exact same thread.

This is how FormsAuthentication works,

1. It checks if Auth Cookie is set or not, it then directs user to login page
2. Login page must validate and set auth cookie, like FormsAuthentication.SetAuthCookie
3. Before every page access, Step 1 is executed.
4. After successful validation of Auth Cookie, ASP.NET internally sets the current user and all differnet parameters according to your membership component.
5. ASP.NET Global.asax file can give you some events where in you can plugin your code to check just after authentication is successful you can change your current user, remember setting your current principle on login page will not help

We had similar issue when we were using session to store certain important information, after auth sessions were not rebuilt, so we wrote a HTTP Module, and in it's init method, we attached AfterRequestAcquired event and in this event you can write your code to instantiate all your important user related variables.

Answer 2

You can handle FormsAuthentication_OnAuthenticate(object sender, FormsAuthenticationEventArgs e) (in Global.asax) and set CurrentPrincipal here.

void FormsAuthentication_OnAuthenticate(object sender, FormsAuthenticationEventArgs e)
{
var phoenixIdentity = new PhoenixIdentity("B", "Forms" , true);
var principal = new PhoenixPrincipal(phoenixIdentity);
e.User = principal;
}