HostedImpersonationContext.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / ServiceModel / System / ServiceModel / Activation / HostedImpersonationContext.cs / 1 / HostedImpersonationContext.cs
                        
                        
                            //------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------
namespace System.ServiceModel.Activation
{ 
    using System.ServiceModel;
    using System.ServiceModel.Diagnostics; 
    using System.Security.Principal; 
    using System.ServiceModel.ComIntegration;
    using System.ServiceModel.Security; 
    using System.Web.Hosting;
    using System.Runtime.InteropServices;
    using System.ComponentModel;
    using System.Threading; 
    using System.Security;
 
    using SafeCloseHandle = System.IdentityModel.SafeCloseHandleCritical; 
    using SMD = System.ServiceModel.Diagnostics;
 
    /// 
    /// RequiresReview - All member methods are security critical. The class might be used outside of the restricted SecurityContext.
    ///                  Ensure they do not accidentally satisfy any demands
    ///  
    [SecurityRequiresReview]
    class HostedImpersonationContext 
    { 
        /// 
        /// Critical - stores the impersonation token handle. since we're allowing "safe" Impersonation of the token we got from asp.net 
        ///            we need to protect this value
        /// 
        [SecurityCritical]
        SafeCloseHandle tokenHandle; 

        ///  
        /// Critical - controls lifetime of token handle, caller must use care 
        /// 
        [SecurityCritical] 
        int refCount = 0;

        /// 
        /// Critical - a security critical field, caller must use care 
        /// 
        [SecurityCritical] 
        bool isImpersonated; 

        ///  
        /// Critical - calls two safe native methods: GetCurrentThread and OpenCurrentThreadToken; and Marshal.GetLastWin32Error
        ///            captures current thread token in a SecurityCritical field
        /// 
        [SecurityCritical] 
        public HostedImpersonationContext()
        { 
            if (ServiceHostingEnvironment.AspNetCompatibilityEnabled) 
            {
                bool isSuccess = SafeNativeMethods.OpenCurrentThreadTokenCritical(SafeNativeMethods.GetCurrentThread(), 
                    TokenAccessLevels.Query | TokenAccessLevels.Impersonate, true,
                    out tokenHandle);

                int error = Marshal.GetLastWin32Error(); 
                if (isSuccess)
                { 
                    isImpersonated = true; 
                    Interlocked.Increment(ref refCount);
                } 
                else
                {
                    SMD.Utility.CloseInvalidOutSafeHandleCritical(tokenHandle);
                    tokenHandle = null; 
                    if (error != (int)Win32Error.ERROR_NO_TOKEN)
                    { 
                        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new Win32Exception(error, SR.GetString(SR.Hosting_ImpersonationFailed))); 
                    }
                } 
            }
        }

        public bool IsImpersonated 
        {
            ///  
            /// Critical - accesses SecurityCritical isImpersonated field 
            /// Safe     - does not leak control or mutable/harmful data, no potential for harm
            ///  
            [SecurityCritical, SecurityTreatAsSafe]
            get
            {
                return isImpersonated; 
            }
        } 
 
        /// 
        /// Critical - accesses SecurityCritical tokenHandle field and uses LinkDemanded DangerousGetHandle method as well as UnsafeCreate 
        ///            caller should use with care, must take responsibility for reverting impersonation
        /// 
        [SecurityCritical]
        public IDisposable Impersonate() 
        {
            if (!isImpersonated) 
                return null; 

            DiagnosticUtility.DebugAssert(tokenHandle != null, "The token handle was incorrectly released earlier."); 
            HostedInnerImpersonationContext context = null;
            lock(tokenHandle)
            {
                context = HostedInnerImpersonationContext.UnsafeCreate(tokenHandle.DangerousGetHandle()); 
                GC.KeepAlive(tokenHandle);
            } 
            return context; 
        }
 
        /// 
        /// Critical - controls lifetime of token handle, caller must use care
        /// 
        [SecurityCritical] 
        public void AddRef()
        { 
            if (IsImpersonated) 
            {
                Interlocked.Increment(ref refCount); 
            }
        }

        ///  
        /// Critical - controls lifetime of token handle, caller must use care
        ///  
        [SecurityCritical] 
        public void Release()
        { 
            if (IsImpersonated)
            {
                DiagnosticUtility.DebugAssert(tokenHandle != null, "The token handle is incorrectly released earlier.");
                int currentCount = Interlocked.Decrement(ref refCount); 
                if (currentCount == 0)
                { 
                    lock(tokenHandle) 
                    {
                        tokenHandle.Close(); 
                        tokenHandle = null;
                    }
                }
            } 
        }
 
        ///  
        /// Critical - keeps track of impersonated user, caller must use with care and call Dispose at the appropriate time
        ///  
        [SecurityCritical(SecurityCriticalScope.Everything)]
        class HostedInnerImpersonationContext : IDisposable
        {
            IDisposable impersonatedContext; 

            HostedInnerImpersonationContext(IDisposable impersonatedContext) 
            { 
                if (impersonatedContext == null)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(
                        SR.GetString(SR.Hosting_ImpersonationFailed)));
                }
                this.impersonatedContext = impersonatedContext; 
            }
 
            public static HostedInnerImpersonationContext UnsafeCreate(IntPtr token) 
            {
                return new HostedInnerImpersonationContext(HostingEnvironmentWrapper.UnsafeImpersonate(token)); 
            }

            public void Dispose()
            { 
                if (impersonatedContext != null)
                { 
                    impersonatedContext.Dispose(); 
                    impersonatedContext = null;
                } 
            }
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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HostedImpersonationContext.cs source code in C# .NET

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