System.Net.Http.WinHttpHandler.WinHttpHandler.SetStatusCallback C# (CSharp) Method

        private void SetStatusCallback(
            SafeWinHttpHandle requestHandle,
            Interop.WinHttp.WINHTTP_STATUS_CALLBACK callback)
        {
            const uint notificationFlags =
                Interop.WinHttp.WINHTTP_CALLBACK_FLAG_ALL_COMPLETIONS |
                Interop.WinHttp.WINHTTP_CALLBACK_FLAG_HANDLES |
                Interop.WinHttp.WINHTTP_CALLBACK_FLAG_REDIRECT |
                Interop.WinHttp.WINHTTP_CALLBACK_FLAG_SEND_REQUEST;

            IntPtr oldCallback = Interop.WinHttp.WinHttpSetStatusCallback(
                requestHandle,
                callback,
                notificationFlags,
                IntPtr.Zero);

            if (oldCallback == new IntPtr(Interop.WinHttp.WINHTTP_INVALID_STATUS_CALLBACK))
            {
                int lastError = Marshal.GetLastWin32Error();
                if (lastError != Interop.WinHttp.ERROR_INVALID_HANDLE) // Ignore error if handle was already closed.
                {
                    throw WinHttpException.CreateExceptionUsingError(lastError);
                }
            }
        }