/// <summary>
/// Undo impersonation for calling thread
/// </summary>
/// <param name="token"></param>
/// <param name="context"></param>
/// <returns></returns>
private static bool UndoImpersonation(ref SafeUserToken token,
ref WindowsImpersonationContext context)
{
if (context != null)
{
context.Undo();
context = null;
}
if (token != null)
{
token.Dispose();
token = null;
}
return(true);
}
internal static extern bool LogonUser(string lpszUsername, string lpszDomain, string lpszPassword, int dwLogonType, int dwLogonProvider, out SafeUserToken hToken);
protected override bool ReleaseHandle()
{
return(SafeUserToken.CloseHandle(base.handle));
}
public static TReturn Impersonate <TReturn, TParameter>(
string userName,
string domain,
SecureString password,
TParameter parameter,
ImpersonationWorkFunction <TReturn, TParameter> impersonationWork,
NativeMethod.LogonType logonMethod,
NativeMethod.LogonProvider provider)
{
// Check the parameters
if (string.IsNullOrEmpty(userName))
{
throw new ArgumentNullException("userName");
}
if (password == null)
{
throw new ArgumentNullException("password");
}
if (impersonationWork == null)
{
throw new ArgumentNullException("impersonationWork");
}
if (logonMethod < NativeMethod.LogonType.LOGON32_LOGON_INTERACTIVE |
NativeMethod.LogonType.LOGON32_LOGON_NEW_CREDENTIALS < logonMethod)
{
throw new ArgumentOutOfRangeException("logonMethod");
}
if (provider < NativeMethod.LogonProvider.LOGON32_PROVIDER_DEFAULT |
NativeMethod.LogonProvider.LOGON32_PROVIDER_WINNT50 < provider)
{
throw new ArgumentOutOfRangeException("provider");
}
IntPtr passwordPtr = IntPtr.Zero;
SafeUserToken token = null;
WindowsImpersonationContext context = null;
try
{
// Convert the password to a string
passwordPtr = Marshal.SecureStringToBSTR(password);
IntPtr handle = IntPtr.Zero;
// Attempts to log a user on to the local computer
if (!NativeMethod.LogonUser(userName, domain, passwordPtr,
logonMethod, provider, out handle))
{
throw new Win32Exception();
}
else
{
token = new SafeUserToken(ref handle);
}
}
finally
{
// Erase the memory that the password was stored in
if (!IntPtr.Zero.Equals(passwordPtr))
{
Marshal.ZeroFreeBSTR(passwordPtr);
}
}
try
{
// Impersonate
Debug.Assert(token != null);
context = WindowsIdentity.Impersonate(token.DangerousGetHandle());
// Call out to the work function
return(impersonationWork(parameter));
}
finally
{
// Clean up
UndoImpersonation(ref token, ref context);
}
}
