clientId on OnTransportEvent does not match the final clientId that is connected to the server

[devfox-se]

Description

My goal is to track player states when they are initiating connection and when their connection fails for some reason before completing it. I cannot use OnClientDisconnectCallback since it is triggered only after client disconnects after successful connection is established.

I decided to subscribe to the NetworkTransport events

NetworkManager.Singleton.NetworkConfig.NetworkTransport.OnTransportEvent += OnTransportEvent;

and handle a particular set of events

private void OnTransportEvent(NetworkEvent eventType, ulong clientId, ArraySegment<byte> payload, float receiveTime)
{
    switch (eventType)
    {
        case NetworkEvent.Connect:
            if (NetworkManager.Singleton.LocalClientId != clientId)
            {
                Debug.Log($"[Transport] Client {clientId} attempting to connect...");
            }    
            break;

        case NetworkEvent.Disconnect:
            if (NetworkManager.Singleton.LocalClientId != clientId)
            {
                Debug.Log($"[Transport] Client {clientId} connection lost or failed.");
            }
            break;

        case NetworkEvent.Data:
            // Ignore or handle raw transport data if needed.
            break;
    }
}

The issue I see here is that OnTransportEvent receives the clientId that is supposed to be the clientId of the player that is connecting but the value does not match the actual clientId that is stored in NetworkManager.Singleton.ConnectedClients after the connection is established.

Actual Outcome

clientId on transport events DOES NOT match the client id that is stored in NetworkManager.Singleton.ConnectedClients and is sent by OnClientConnectedCallback and OnClientDisconnectedCallback events

Expected Outcome

The clientId value must be the same for all events

Environment

• OS: Win11
• Unity Version: [e.g. 2022.3.62f]
• Netcode Version: [e.g. 1.14.1]
• Netcode Topology: Client-Server

[EmandM]

Hi! Thanks for reporting this. Out of interest, what is your use-case for using this id?

I see that the naming on that event is confusing. The clientId that you are referring to on the OnTransportEvent is the transport's understanding of a client. Outside of the transport layer, we refer to that id as the transportId. We can't know the correct LocalClientId of the client who sent a Transport.Connect message as we haven't connected them to the Netcode system yet and so we don't actually know their clientId until the full connection handshake has happened.

It is important for security to not tell other clients the transportId of any other connected client. The transportId is how NGO calculates whether a packet was actually sent from the user who said they sent it. If other connected clients know that transportId, it becomes much easier to send malicious packets that pretend to be a user that they aren't.

We do have two functions that may be helpful hereNeworkManager.GetTransportIdFromClientId(ngo_clientId) and NeworkManager.GetClientIdFromTransportId(transport_clientId). These will let you translate between the transportId and the clientId during the game runtime.

[devfox-se]

Out of interest, what is your use-case for using this id?

Thanks for your reply, the use case is to make the server know that there are clients that are still connecting to the "lobby" scene so that server should wait before closing the lobby and let players complete the loading. For that purpose I want to keep a list of pending client ids and pop clientIds from that tracklist once OnClientConnectionCallback is fired

Thank you for pointing the methods I can use, I'll look into it!