C# .Net Native AoT - How to get pointer to Managed class to pass as parameter to Com Object

Question

C# .Net Native AoT - How to get pointer to Managed class to pass as parameter to Com Object

Gueztt 1

I have implemented INetworkListManagerEvents interface to get network connectivity state changes as a C# class.

In my project, the INetworkListManagerEvents is code generated via CsWin32 source generator.

Now at some point I have to use IConnectionPoint::Advise for it to work as intended.

How can I pass the instance of my C# class implementing INetworkListManagerEvents to IConnectionPoint::Advise as IUnknown*.

I can't use Marshal class so to make it trim friendly and have Native AoT compatibility.

Edit 1:

Above scenario is just for an example. There are other scenarios where event sinks needs to be implemented in c#, to get notified about, where c# managed class needs to be passed as pointer to the relevant Advise(...) function for it to work.

RLWA32 50,071 Reputation points

2025-07-23T18:38:56.6+00:00

The following documentation looks like it might be helpful for you. https://learn.microsoft.com/en-us/dotnet/standard/native-interop/tutorial-comwrappers

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RLWA32 50,071 Reputation points

2025-07-23T18:38:56.6+00:00

The following documentation looks like it might be helpful for you. https://learn.microsoft.com/en-us/dotnet/standard/native-interop/tutorial-comwrappers

Answer 1

You can call Advise inside the class and use this.

This test works for on my Windows 10 22H2 OS :

public partial class NetworkListManagerEventsClass : INetworkListManagerEvents
{
    private INetworkListManager nlm;
    private IConnectionPoint cp;
    private int nCookie = 0;

    public NetworkListManagerEventsClass()
    {
        nlm = new NetworkListManager();
        IConnectionPointContainer cpc = (IConnectionPointContainer)nlm;
        if (cpc != null)
        {
            Guid guid = typeof(INetworkListManagerEvents).GUID;
            cpc.FindConnectionPoint(ref guid, out cp);
            cp.Advise(this, out nCookie);
        }
    }

    ~NetworkListManagerEventsClass()
    {
        cp.Unadvise(nCookie);
    }

    void INetworkListManagerEvents.ConnectivityChanged(NLM_CONNECTIVITY newConnectivity)
    {
        if ((newConnectivity & NLM_CONNECTIVITY.NLM_CONNECTIVITY_DISCONNECTED) != 0)
        {
            System.Diagnostics.Debug.WriteLine("Disconnected");
        }
        if ((newConnectivity & NLM_CONNECTIVITY.NLM_CONNECTIVITY_IPV4_LOCALNETWORK) != 0  ||
            (newConnectivity & NLM_CONNECTIVITY.NLM_CONNECTIVITY_IPV6_LOCALNETWORK) != 0)
        {
            System.Diagnostics.Debug.WriteLine("Local Network");
        }
        if ((newConnectivity & NLM_CONNECTIVITY.NLM_CONNECTIVITY_IPV4_INTERNET) != 0 ||
            (newConnectivity & NLM_CONNECTIVITY.NLM_CONNECTIVITY_IPV6_INTERNET) != 0)
        {
            System.Diagnostics.Debug.WriteLine("Internet");
        }
    }
}

Gueztt 1 Reputation point

2025-07-23T16:22:24.93+00:00

@Castorix31 Thank you for your time. This doesn't work as all the native objects are generated by CsWin32 source generator. I had this kind of scenarios working well, but I wanted to try AoT optimisation. IConnectionPoint.Advise expects Iunknown* pointer. I am out of ideas how to convert managed class to IUnknown* without using Marshal class to make it AoT compatible.

For this instance, I'm just going to do polling with timer using INetworkListManager::GetConnectivity. Bit I'm not sure there can be alternate ways to accomplish same for other such cases.

Would you be knowing any possible way to convert managed class to IUnknown* without using Marshal class to ensure AoT compatibility.

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C# .Net Native AoT - How to get pointer to Managed class to pass as parameter to Com Object

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