GodotTicTacToe/scripts/Net.cs

using Godot;
using System;

public class Net : Node {
    
    private PacketPeerUDP PacketPeer;
    private Client Client;
    private Server Server;

    public bool IsClient { get { return Client != null; } }
    public bool IsServer { get { return Server != null; } }

    public override void _Ready() {
        PacketPeer = new PacketPeerUDP();
    }

    public override void _Process(float delta) {
        if (IsServer) { Server.Update(delta); }
        if (IsClient) { Client.Update(delta); }
    }

    public override void _ExitTree() {
        if (IsServer) { Server.Free(); }
        if (IsClient) { Client.Free(); }
    }

    public void StartClient(string address, int port) {
        if (IsClient || IsServer) { return; }
        Client = new Client(PacketPeer);
        Client.Initialize(address, port);
    }

    public void StartServer(string address, int port) {
        if (IsClient || IsServer) { return; }
        Server = new Server(PacketPeer);
        Server.Initialize(address, port);
    }
}