using System using System Collections Generic using System Text using

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using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Principal;
using System.Runtime.InteropServices;
using System.Security.Permissions;
namespace WindowsFormsApplication1
{
public class ImpersonateUser
{
[DllImport("advapi32.dll", SetLastError = true)]
public static extern bool LogonUser(
String lpszUsername,
String lpszDomain,
String lpszPassword,
int dwLogonType,
int dwLogonProvider,
ref IntPtr phToken);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public extern static bool CloseHandle(IntPtr handle);
private static IntPtr tokenHandle = new IntPtr(0);
private static WindowsImpersonationContext impersonatedUser;
// If you incorporate this code into a DLL, be sure to demand that it
// runs with FullTrust.
[PermissionSetAttribute(SecurityAction.Demand, Name = "FullTrust")]
public void Impersonate(string domainName, string userName, string password)
{
//try
{
// Use the unmanaged LogonUser function to get the user token for
// the specified user, domain, and password.
const int LOGON32_PROVIDER_DEFAULT = 0;
// Passing this parameter causes LogonUser to create a primary token.
const int LOGON32_LOGON_INTERACTIVE = 2;
tokenHandle = IntPtr.Zero;
// ---- Step - 1
// Call LogonUser to obtain a handle to an access token.
bool returnValue = LogonUser(
userName,
domainName,
password,
LOGON32_LOGON_INTERACTIVE,
LOGON32_PROVIDER_DEFAULT,
ref tokenHandle); // tokenHandle - new security token
if (false == returnValue)
{
int ret = Marshal.GetLastWin32Error();
throw new System.ComponentModel.Win32Exception(ret);
}
// ---- Step - 2
WindowsIdentity newId = new WindowsIdentity(tokenHandle);
// ---- Step - 3
impersonatedUser = newId.Impersonate();
}
}
// Stops impersonation
public void Undo()
{
impersonatedUser.Undo();
// Free the tokens.
if (tokenHandle != IntPtr.Zero)
CloseHandle(tokenHandle);
}
}
}