WindowsImpersonationContext.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Security / Principal / WindowsImpersonationContext.cs / 1305376 / WindowsImpersonationContext.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// [....]
// 
 
//
// WindowsImpersonationContext.cs 
//
// Representation of an impersonation context.
//
 
namespace System.Security.Principal
{ 
    using Microsoft.Win32; 
    using Microsoft.Win32.SafeHandles;
    using System.Runtime.InteropServices; 
#if FEATURE_CORRUPTING_EXCEPTIONS
    using System.Runtime.ExceptionServices;
#endif // FEATURE_CORRUPTING_EXCEPTIONS
    using System.Security.Permissions; 
    using System.Runtime.ConstrainedExecution;
    using System.Runtime.Versioning; 
    using System.Diagnostics.Contracts; 

    [System.Runtime.InteropServices.ComVisible(true)] 
    public class WindowsImpersonationContext : IDisposable {
        [System.Security.SecurityCritical /*auto-generated*/]
        private SafeTokenHandle m_safeTokenHandle = SafeTokenHandle.InvalidHandle;
        private WindowsIdentity m_wi; 
        private FrameSecurityDescriptor m_fsd;
 
        [System.Security.SecurityCritical]  // auto-generated 
        private WindowsImpersonationContext () {}
 
        [System.Security.SecurityCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
        internal WindowsImpersonationContext (SafeTokenHandle safeTokenHandle, WindowsIdentity wi, bool isImpersonating, FrameSecurityDescriptor fsd) { 
            if (safeTokenHandle.IsInvalid)
                throw new ArgumentException(Environment.GetResourceString("Argument_InvalidImpersonationToken")); 
            Contract.EndContractBlock(); 

            if (isImpersonating) { 
                if (!Win32Native.DuplicateHandle(Win32Native.GetCurrentProcess(),
                                                 safeTokenHandle,
                                                 Win32Native.GetCurrentProcess(),
                                                 ref m_safeTokenHandle, 
                                                 0,
                                                 true, 
                                                 Win32Native.DUPLICATE_SAME_ACCESS)) 
                    throw new SecurityException(Win32Native.GetMessage(Marshal.GetLastWin32Error()));
                m_wi = wi; 
            }
            m_fsd = fsd;
        }
 
        // Revert to previous impersonation (the only public method).
        [System.Security.SecuritySafeCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)] 
        [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
        public void Undo () { 
            int hr = 0;
            if (m_safeTokenHandle.IsInvalid) { // the thread was not initially impersonating
                hr = Win32.RevertToSelf();
                if (hr < 0) 
                    Environment.FailFast(Win32Native.GetMessage(hr));
            } else { 
                hr = Win32.RevertToSelf(); 
                if (hr < 0)
                    Environment.FailFast(Win32Native.GetMessage(hr)); 
                hr = Win32.ImpersonateLoggedOnUser(m_safeTokenHandle);
                if (hr < 0)
                    throw new SecurityException(Win32Native.GetMessage(hr));
            } 
            WindowsIdentity.UpdateThreadWI(m_wi);
            if (m_fsd != null) 
                m_fsd.SetTokenHandles(null, null); 
        }
 
        // Non-throwing version that does not new any exception objects. To be called when reliability matters
        [System.Security.SecurityCritical]  // auto-generated
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        [ResourceExposure(ResourceScope.None)] 
        [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
#if FEATURE_CORRUPTING_EXCEPTIONS 
        [HandleProcessCorruptedStateExceptions] // 
#endif // FEATURE_CORRUPTING_EXCEPTIONS
        internal bool UndoNoThrow() 
        {
            bool bRet = false;
            try{
                int hr = 0; 
                if (m_safeTokenHandle.IsInvalid)
                { // the thread was not initially impersonating 
                    hr = Win32.RevertToSelf(); 
                    if (hr < 0)
                        Environment.FailFast(Win32Native.GetMessage(hr)); 
                }
                else
                {
                    hr = Win32.RevertToSelf(); 
                    if (hr >= 0)
                    { 
                        hr = Win32.ImpersonateLoggedOnUser(m_safeTokenHandle); 
                    }
                    else 
                    {
                        Environment.FailFast(Win32Native.GetMessage(hr));
                    }
                } 
                bRet = (hr >= 0);
                if (m_fsd != null) 
                    m_fsd.SetTokenHandles(null,null); 
            }
            catch 
            {
                bRet = false;
            }
            return bRet; 
        }
 
        // 
        // IDisposable interface.
        // 

        [System.Security.SecuritySafeCritical]  // auto-generated
        [ComVisible(false)]
        protected virtual void Dispose(bool disposing) { 
            if (disposing) {
                if (m_safeTokenHandle != null && !m_safeTokenHandle.IsClosed) { 
                    Undo(); 
                    m_safeTokenHandle.Dispose();
                } 
            }
        }

        [System.Security.SecuritySafeCritical]  // auto-generated 
        [ComVisible(false)]
        public void Dispose () { 
            Dispose(true); 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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WindowsImpersonationContext.cs source code in C# .NET

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