ASP.NET impersonation from code (C#) and connected SQL Server Express user

Question

I'm having trouble with ASP.NET impersonation from code (C#) and using SQL Server Express:

I'm able to impersonate successfully and connect to SQL Server, however executing SELECT CURRENT_USER returns guest instead of TestUser_001.

Note: I've tried impersonation with LOGON32_LOGON_NETWORK_CLEARTEXT and then with LOGON32_LOGON_INTERACTIVE when calling LogonUser - the result remains the same. Account from which I'm executing this impersonation code has Act as part of the operating system set. Tested under IIS Express (F5 from Visual Studio 2013). I never logged in interactively as TestUser_001 and connected to SQL Server Express instance - there is no MY_DOMAIN\TestUser_001 under Security\Logins - would like for this to happen automatically when using the code.

using (var impersonation = new ImpersonationHelper("TestUser_001", "MY_DOMAIN", "pass"))
{
    using (var conn = new SqlConnection(@"Data Source=MY_DOMAIN\SQLEXPRESS;Integrated Security=True;"))
    {
        conn.Open();

        using (var cmd = conn.CreateCommand())
        {
            cmd.CommandText = "SELECT CURRENT_USER";
            var result = cmd.ExecuteScalar();
        }
    }
}

Here is the rudimentary ImpersonationHelper implementation:

public class ImpersonationHelper : IDisposable
{
    public const int LOGON32_LOGON_INTERACTIVE = 2;
    public const int LOGON32_LOGON_NETWORK_CLEARTEXT = 8;
    public const int LOGON32_PROVIDER_DEFAULT = 0;

    [DllImport("advapi32.dll")]
    public static extern int LogonUser(
        string lpszUsername,
        string lpszDomain,
        string lpszPassword,
        int dwLogonType,
        int dwLogonProvider,
        ref IntPtr phToken
    );

    [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern int DuplicateToken(
        IntPtr hToken,
        int impersonationLevel,
        ref IntPtr hNewToken
    );

    [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern bool RevertToSelf();

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public static extern bool CloseHandle(IntPtr handle);

    private readonly WindowsImpersonationContext impersonationContext_;

    public ImpersonationHelper(string username, string domain, string password)
    {
        var token = IntPtr.Zero;
        var token_duplicate = IntPtr.Zero;

        if (RevertToSelf())
        {
            if (LogonUser(username, domain, password, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref token) != 0)
            {
                if (DuplicateToken(token, 2, ref token_duplicate) != 0)
                {
                    var temp_windows_identity = new WindowsIdentity(token_duplicate);
                    impersonationContext_ = temp_windows_identity.Impersonate();

                    if (impersonationContext_ != null)
                    {
                        CloseHandle(token);
                        CloseHandle(token_duplicate);
                        return;
                    }
                }
            }
        }

        if (token != IntPtr.Zero)
            CloseHandle(token);

        if (token_duplicate != IntPtr.Zero)
            CloseHandle(token_duplicate);

        throw new Exception(string.Format("Unable to impersonate as {0}\\{1}.", username, domain));
    }

    public void Dispose()
    {
        impersonationContext_.Undo();
    }
}

Answer 1

Thank you Dan Guzman - SQL Server MVP and all others that helped with this question. I guess I'll mark this as an answer since the impersonation works and correct user is reported by SQL Server.