Impersonate Class

Impersonator.cs

namespace ImpersonateTestApp
{
    public class Impersonator :
        IDisposable
    {
        #region Public methods.
        public Impersonator(
            string userName,
            string domainName,
            string password)
        {
            ImpersonateValidUser(userName, domainName, password);
        }
        // -----------------------------------------------------------------
        #endregion
        #region IDisposable member.
        // ---------------------------------------------------------
        public void Dispose()
        {
            UndoImpersonation();
        }
        // -----------------------------------------------------------------
        #endregion
        
        #region P/Invoke.
        // ---------------------------------------------------------
        [DllImport("advapi32.dll", SetLastError = true)]
        private 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)]
        private static extern int DuplicateToken(
            IntPtr hToken,
            int impersonationLevel,
            ref IntPtr hNewToken);
            
        [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern bool RevertToSelf();
        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        private static extern bool CloseHandle(
            IntPtr handle);
        private const int LOGON32_LOGON_INTERACTIVE = 2;
        private const int LOGON32_PROVIDER_DEFAULT = 0;
        // -----------------------------------------------------------------
        #endregion
        
        #region Private member.
        // ---------------------------------------------------------
        private void ImpersonateValidUser(
            string userName,
            string domain,
            string password)
        {
            WindowsIdentity tempWindowsIdentity = null;
            IntPtr token = IntPtr.Zero;
            IntPtr tokenDuplicate = IntPtr.Zero;
         try
            {
                if (RevertToSelf())
                {
                    if (LogonUser(
                        userName,
                        domain,
                        password,
                        LOGON32_LOGON_INTERACTIVE,
                        LOGON32_PROVIDER_DEFAULT,
                        ref token) != 0)
                    {
                        if (DuplicateToken(token, 2, ref tokenDuplicate) != 0)
                        {
                            tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
                            impersonationContext = tempWindowsIdentity.Impersonate();
                        }
                        else
                        {
                            throw new Win32Exception(Marshal.GetLastWin32Error());
                        }
                    }
                    else
                    {
                        throw new Win32Exception(Marshal.GetLastWin32Error());
                    }
                }
                else
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            finally
            {
                if (token != IntPtr.Zero)
                {
                    CloseHandle(token);
                }
                if (tokenDuplicate != IntPtr.Zero)
                {
                    CloseHandle(tokenDuplicate);
                }
            }
        }
        /// <summary>
        /// Reverts the impersonation.
        /// </summary>
        private void UndoImpersonation()
        {
            if (impersonationContext != null)
            {
                impersonationContext.Undo();
            }
        }
        private WindowsImpersonationContext impersonationContext = null;
        // -----------------------------------------------------------------
        #endregion
    }
}