pinvoke.net: Edit: advapi32.OpenThreadToken

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Summary: Opens the access token associated with a thread

!!!!C# Signature:
 [DllImport("advapi32.dll", SetLastError=true)]
 static extern bool OpenThreadToken(
 	IntPtr ThreadHandle,
 	uint DesiredAccess,
 	bool OpenAsSelf,
 	out IntPtr TokenHandle);
!!!!VB Signature:
 Declare Function OpenThreadToken Lib "advapi32.dll" (
   ThreadHandle As IntPtr,
   DesiredAccess As Integer,
   OpenAsSelf As Boolean,
   ByRef TokenHandle As IntPtr) As Boolean
!!!!User-Defined Types:
None.

!!!!Notes:
None.

!!!!Tips & Tricks:
Please add some!

!!!!Sample Code:
/// <summary>
/// HoldImpersonationCloak enables temporarily dropping the 'cloak' of 
/// impersonation to access items as the process identity, so hiding another 
/// account/password pair is not required.  Useful in double-hop
/// situations where the process ID can be safely used for remote access.
/// </summary>
/// <example>
///     using (HoldImpersonationCloak hic = new HoldImpersonationCloak())
///     {
///         //operate here as process identity
///         GC.KeepAlive(hic); //prevent over-eager garbage collection optimization from taking it too soon
///     }
/// </example>
public class HoldImpersonationCloak : IDisposable
{
    #region Constants

//Some declarations and code taken from http://support.microsoft.com/kb/306158/,
    // http://pluralsight.com/wiki/default.aspx/Keith.GuideBook/HowToImpersonateAUserGivenHerToken.html,
    // http://pluralsight.com/wiki/default.aspx/Keith.GuideBook/HowToCreateAWindowsPrincipalGivenAToken.html,
    // http://www.pinvoke.net

private const int TOKEN_READ = 0x00020008; //From VC\PlatformSDK\Include\Winnt.h
    private const int TOKEN_IMPERSONATE = 0x0004;
    private const int ERROR_NO_TOKEN = 1008; //From VC\PlatformSDK\Include\WinError.h

#endregion

#region External Declarations

[System.Runtime.InteropServices.DllImport("kernel32.dll", SetLastError = true)]
    private static extern IntPtr GetCurrentThread();

[System.Runtime.InteropServices.DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool OpenThreadToken(IntPtr ThreadHandle,
        uint DesiredAccess,
        bool OpenAsSelf,
        out IntPtr TokenHandle);

[System.Runtime.InteropServices.DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool SetThreadToken(IntPtr pHandle,
        IntPtr hToken);

[System.Runtime.InteropServices.DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool RevertToSelf();

[System.Runtime.InteropServices.DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool CloseHandle(IntPtr handle);

#endregion

#region Variables

private IntPtr hToken = IntPtr.Zero;
    private int dw;
    
    #endregion

public HoldImpersonationCloak()
	{
        if (!OpenThreadToken(GetCurrentThread(), TOKEN_READ | TOKEN_IMPERSONATE, true, out hToken))
        {
            dw = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
            if (ERROR_NO_TOKEN == dw) // 
            {
                System.Diagnostics.Trace.WriteLine("Not impersonating, cloak is a no-op!", "Impersonation");
            }
            else
            {
                System.Diagnostics.Trace.WriteLine("Unexpected error 0x" + dw.ToString("x4") + " on OpenThreadToken", "Impersonation");
            }
            hToken = IntPtr.Zero;
        }
        else
        {
            if (!RevertToSelf())
            {
                dw = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
                System.Diagnostics.Trace.WriteLine("Failed to revert!, error 0x" + dw.ToString("x4"), "Impersonation");
            }
        }
    }

//Implement IDisposable. (from Implementing Finalize and Dispose to Clean Up Unmanaged Resources )
   public void Dispose() 
   {
        Dispose(true);
        GC.SuppressFinalize(this); 
   }

protected virtual void Dispose(bool disposing) 
   {
      if (disposing) 
      {
         // Free other state (managed objects).
          if (IntPtr.Zero != hToken)
          {
              if (!SetThreadToken(IntPtr.Zero, hToken))
              {
                  dw = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
                  System.Diagnostics.Trace.WriteLine("Could not reset cloak!, error 0x" + dw.ToString("x4"), "Impersonation");
              }
          }

}
      // Free your own state (unmanaged objects).
      if (IntPtr.Zero != hToken)
      {
          if (!CloseHandle(hToken))
          {
              dw = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
              System.Diagnostics.Trace.WriteLine("Could not close cloak token!, error 0x" + dw.ToString("x4"), "Impersonation"); ;
          }
          hToken = IntPtr.Zero;
      }
     // Set large fields to null.
   }

// Use C# destructor syntax for finalization code.
    ~HoldImpersonationCloak()
   {
      // Simply call Dispose(false).
      Dispose (false);
   }

}

!!!!Alternative Managed API:
Do you know one?  Please contribute it!

Documentation: OpenThreadToken@msdn on MSDN