Inconsistent message data

[AriaTheCurseling]

Describe the bug
Seemingly randomly receives the wrong value

Calling Code

// Is not consistent, but it seems to happen about 1 in 20 times.
void BUG() {
        server = SteamNetworkingSockets.CreateRelaySocket<SocketManager>(0);
        manager = SteamNetworkingSockets.ConnectRelay<ConnectionManager>(SteamClient.SteamId, 0);

        server.onConnecting += OnServerConnectionAttempt;
        server.onMessage += OnMessage;

		var data = MemoryMarshal.AsBytes<int>(new int[1] {42});

		manager.Connection.SendMessage(data);
}

void OnMessage(ReadOnlySpan<byte> data, Connection connection, NetIdentity identity, long messageNum, long recvTime, int channel){
        int value = MemoryMarshal.Read<int>(data);

        UnityEngine.Debug.Log($"Received message: Message data size: {data.Length}, {value}");
}

[AriaTheCurseling]

Issue located:
GCHandle.Alloc in NetMsg forces a move of the data, but C# only moves the first byte of the span.

The issue is fully reproducible when using a value that requires multiple bytes to store.

Possible solutions:

• Send T[] instead of Span
• Use fixed instead of addrOfFixedObject to prevent the move
• The Memory may also work as a replacement for Span, as it is designed for thread safety