OnUnnamedMessage callback shows the local client ID as the sender

[simtrip]

Description
I'm currently having an issue with Unnamed Messages that going by documentation would suggest this is a bug. Forgive me if I've misunderstood the intent of this part of the API.

The summary for UnnamedMessageDelegate describes the parameter clientId as:

The clientId that sent the message

However, when subscribing to CustomMessagingManager.OnUnnamedMessage, the clientId parameter passed into the invoked subscriber seems to be the value of the receiving user's client ID, not the sender of the message.

To Reproduce

1. Subscribe to the CustomMessagingManager.OnUnnamedMessage event.
2. Send a message from the host using CustomMessagingManager.SendUnnamedMessage passing null to send to all clients.
3. When the client's subscriber is invoked observe that the value of clientId is not the sender but is equivalent to NetworkManager.LocalClientId

Environment

• OS: Windows 10
• Unity Version: 2020.3.14f1
• MLAPI Version: 0.1.0

Additional context
This was tested between the Unity Editor running as host and a build on the same machine as client.
The MonoBehaviour class I used to test this is below.

using System.IO;
using MLAPI.Messaging;
using MLAPI.Serialization.Pooled;
using UnityEngine;

public class UnnamedMessageTest : MonoBehaviour
{
    [SerializeField]
    private string _messageContent = "Hello";

    private void Awake()
    {
        CustomMessagingManager.OnUnnamedMessage += HandleUnnamedMessage;
    }

    [ContextMenu("Send")]
    private void Send()
    {
        using var buffer = PooledNetworkBuffer.Get();
        using var writer = PooledNetworkWriter.Get(buffer);
        writer.WriteString(_messageContent);
        
        // Send to all clients
        CustomMessagingManager.SendUnnamedMessage(null, buffer);
    }

    private void HandleUnnamedMessage(ulong sender, Stream stream)
    {
        using var reader = PooledNetworkReader.Get(stream);
        var content = reader.ReadString();
        
        Debug.LogFormat("Received unnamed message from sender {0} with content {1}", sender, content);
    }
}

[LukeStampfli]

Might be related to #989

[will-mearns]

fyi, @andrews-unity

[TheCaveOfWonders]

I'm seeing the same issue with Named Messages as well, I'm also using UNetTransport.
Can confirm the issue went away when I switched transport from UNetTransport to LiteNetTransport.

[ShadauxCat]

Is this issue still occurring? I made some changes a while back (#1368) that I think should have fixed this. Can you confirm if your issues are resolved in the latest version?

[SenshiSentou]

@ShadauxCat I just encountered this exact bug on 1.0.0-pre.4, on named messages.

The host (id 0) sends a handshake to the client (id 1), who then receives the message, but sees the senderId as 1. This is on UNetTransport.

[ShadauxCat]

@ShadauxCat I just encountered this exact bug on 1.0.0-pre.4, on named messages.

The host (id 0) sends a handshake to the client (id 1), who then receives the message, but sees the senderId as 1. This is on UNetTransport.

@SenshiSentou already fixed in pr #1597

[SenshiSentou]

@ShadauxCat Awesome, thanks! Any word on when this will be back-ported to the package? Or can we apply this patch on top of it?

[simtrip]

Hi, sorry it's taken me so long to retest this, but it's looking good now 👍

I adjusted my script quite a bit and tried it with 1.0.0-pre6. It seems to successfully report that a client (id 1) receiving an unnamed message from the server (id 0) is receiving it from id 0 as intended.

Below is the updated script

using System.Collections.Generic;
using Unity.Collections;
using Unity.Netcode;
using UnityEngine;

public class UnnamedMessageTest : MonoBehaviour
{
    [SerializeField]
    private string _messageContent = "Hello";
    
    private void Start()
    {
        NetworkManager.Singleton.OnServerStarted += HandleServerStarted;
        NetworkManager.Singleton.OnClientConnectedCallback += SingletonOnOnClientConnectedCallback;
    }
    
    private void HandleServerStarted()
    {
        NetworkManager.Singleton.CustomMessagingManager.OnUnnamedMessage += HandleUnnamedMessage;
    }

    private void SingletonOnOnClientConnectedCallback(ulong obj)
    {
        if (NetworkManager.Singleton.IsClient)
        {
            NetworkManager.Singleton.CustomMessagingManager.OnUnnamedMessage += HandleUnnamedMessage;
        }
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.S))
        {
            NetworkManager.Singleton.StartServer();
        }
        
        if (Input.GetKeyDown(KeyCode.C))
        {
            NetworkManager.Singleton.StartClient();
        }
        
        if (Input.GetKeyDown(KeyCode.Space))
        {
            Send();
        }
    }

    [ContextMenu("Send")]
    private void Send()
    {
        Debug.Log("send");
        
        var buffer = new FastBufferWriter(100, Allocator.Temp);
        buffer.WriteValueSafe(_messageContent);
        
        // Send to all clients
        var clients = new List<ulong>(NetworkManager.Singleton.ConnectedClientsIds);
        clients.Add(NetworkManager.Singleton.LocalClientId);
        
        NetworkManager.Singleton.CustomMessagingManager.SendUnnamedMessage(clients, buffer);
    }

    private void HandleUnnamedMessage(ulong sender, FastBufferReader reader)
    {
        reader.ReadValueSafe(out string value);
        Debug.LogFormat("This client {0} Received unnamed message from sender {1} with content {2}", NetworkManager.Singleton.LocalClientId, sender, value);
    }
}