Impersonating Users - e.g. For Unit Tests

http://platinumdogs.wordpress.com/2008/10/30/net-c-impersonation-with-network-credentials/

//---code below---

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security.Principal;

namespace Tools.Network
{
public enum LogonType
{
LOGON32_LOGON_INTERACTIVE = 2,
LOGON32_LOGON_NETWORK = 3,
LOGON32_LOGON_BATCH = 4,
LOGON32_LOGON_SERVICE = 5,
LOGON32_LOGON_UNLOCK = 7,
LOGON32_LOGON_NETWORK_CLEARTEXT = 8, // Win2K or higher
LOGON32_LOGON_NEW_CREDENTIALS = 9 // Win2K or higher
};

public enum LogonProvider
{
LOGON32_PROVIDER_DEFAULT = 0,
LOGON32_PROVIDER_WINNT35 = 1,
LOGON32_PROVIDER_WINNT40 = 2,
LOGON32_PROVIDER_WINNT50 = 3
};

public enum ImpersonationLevel
{
SecurityAnonymous = 0,
SecurityIdentification = 1,
SecurityImpersonation = 2,
SecurityDelegation = 3
}

class Win32NativeMethods
{
[DllImport("advapi32.dll", SetLastError = true)]
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);
}

///

/// Allows code to be executed under the security context of a specified user account.
///

///
///
/// Implements IDispose, so can be used via a using-directive or method calls;
/// ...
///
/// var imp = new Impersonator( "myUsername", "myDomainname", "myPassword" );
/// imp.UndoImpersonation();
///
/// ...
///
/// var imp = new Impersonator();
/// imp.Impersonate("myUsername", "myDomainname", "myPassword");
/// imp.UndoImpersonation();
///
/// ...
///
/// using ( new Impersonator( "myUsername", "myDomainname", "myPassword" ) )
/// {
/// ...
/// [code that executes under the new context]
/// ...
/// }
///
/// ...
///
public class Impersonator : IDisposable
{
private WindowsImpersonationContext _wic;

///

/// Begins impersonation with the given credentials, Logon type and Logon provider.
///

///
Name of the user.
///
Name of the domain.
///
The password.
///
Type of the logon.
///
The logon provider.
public Impersonator(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
{
Impersonate(userName, domainName, password, logonType, logonProvider);
}

///

/// Begins impersonation with the given credentials.
///

///
Name of the user.
///
Name of the domain.
///
The password.
public Impersonator(string userName, string domainName, string password)
{
Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
}

///

/// Initializes a new instance of the class.
///

public Impersonator()
{}

///

/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
///

public void Dispose()
{
UndoImpersonation();
}

///

/// Impersonates the specified user account.
///

///
Name of the user.
///
Name of the domain.
///
The password.
public void Impersonate(string userName, string domainName, string password)
{
Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
}

///

/// Impersonates the specified user account.
///

///
Name of the user.
///
Name of the domain.
///
The password.
///
Type of the logon.
///
The logon provider.
public void Impersonate(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
{
UndoImpersonation();

IntPtr logonToken = IntPtr.Zero;
IntPtr logonTokenDuplicate = IntPtr.Zero;
try
{
// revert to the application pool identity, saving the identity of the current requestor
_wic = WindowsIdentity.Impersonate(IntPtr.Zero);

// do logon & impersonate
if (Win32NativeMethods.LogonUser(userName,
domainName,
password,
(int)logonType,
(int)logonProvider,
ref logonToken) != 0)
{
if (Win32NativeMethods.DuplicateToken(logonToken, (int)ImpersonationLevel.SecurityImpersonation, ref logonTokenDuplicate) != 0)
{
var wi = new WindowsIdentity(logonTokenDuplicate);
wi.Impersonate(); // discard the returned identity context (which is the context of the application pool)
}
else
throw new Win32Exception(Marshal.GetLastWin32Error());
}
else
throw new Win32Exception(Marshal.GetLastWin32Error());
}
finally
{
if (logonToken != IntPtr.Zero)
Win32NativeMethods.CloseHandle(logonToken);

if (logonTokenDuplicate != IntPtr.Zero)
Win32NativeMethods.CloseHandle(logonTokenDuplicate);
}
}

///

/// Stops impersonation.
///

private void UndoImpersonation()
{
// restore saved requestor identity
if (_wic != null)
_wic.Undo();
_wic = null;
}
}
}