com.unity.services.samples.game-lobby/Assets/Scripts/Relay/RelayUtpHost.cs

using System.Collections.Generic;
using Unity.Networking.Transport;
using MsgType = LobbyRelaySample.Relay.RelayUtpSetup.MsgType;

namespace LobbyRelaySample.Relay
{
    /// <summary>
    /// In addition to maintaining a heartbeat with the Relay server to keep it from timing out, the host player must pass network events
    /// from clients to all other clients, since they don't connect to each other.
    /// </summary>
    public class RelayUtpHost : RelayUtpClient, IReceiveMessages
    {
        public override void Initialize(NetworkDriver networkDriver, List<NetworkConnection> connections, LobbyUser localUser, LocalLobby localLobby)
        {
            base.Initialize(networkDriver, connections, localUser, localLobby);
            m_hasSentInitialMessage = true; // The host will be alone in the lobby at first, so they need not send any messages right away.
            Locator.Get.Messenger.Subscribe(this);
        }
        protected override void Uninitialize()
        {
            base.Uninitialize();
            Locator.Get.Messenger.Unsubscribe(this);
        }

        protected override void OnUpdate()
        {
            base.OnUpdate();
            DoHeartbeat();
        }

        /// <summary>
        /// When a new client connects, they need to be given all up-to-date info.
        /// </summary>
        private void OnNewConnection(NetworkConnection conn)
        {
            // When a new client connects, they need to be updated with the current state of everyone else.
            // (We can't exclude this client from the events we send to it, since we don't have its ID in strm, but it will ignore messages about itself on arrival.)
            foreach (var user in m_localLobby.LobbyUsers)
                ForceFullUserUpdate(m_networkDriver, conn, user.Value);
        }

        protected override void ProcessNetworkEventDataAdditional(NetworkConnection conn, DataStreamReader strm, MsgType msgType, string id)
        {
            // Note that the strm contents might have already been consumed, depending on the msgType.

            // Forward messages from clients to other clients.
            if (msgType == MsgType.PlayerName)
            {
                string name = m_localLobby.LobbyUsers[id].DisplayName;
                foreach (NetworkConnection otherConn in m_connections)
                {
                    if (otherConn == conn)
                        continue;
                    WriteString(m_networkDriver, otherConn, id, msgType, name);
                }
            }
            else if (msgType == MsgType.Emote || msgType == MsgType.ReadyState)
            {
                byte value = msgType == MsgType.Emote ? (byte)m_localLobby.LobbyUsers[id].Emote : (byte)m_localLobby.LobbyUsers[id].UserStatus;
                foreach (NetworkConnection otherConn in m_connections)
                {
                    if (otherConn == conn)
                        continue;
                    WriteByte(m_networkDriver, otherConn, id, msgType, value);
                }
            }

            // If a client has changed state, check if this changes whether all players have readied.
            if (msgType == MsgType.ReadyState)
                CheckIfAllUsersReady();
        }

        protected override void ProcessDisconnectEvent(NetworkConnection conn, DataStreamReader strm)
        {
            // TODO: If a client disconnects, see if remaining players are all already ready.
        }

        public void OnReceiveMessage(MessageType type, object msg)
        {
            if (type == MessageType.LobbyUserStatus)
                CheckIfAllUsersReady();
            else if (type == MessageType.EndGame) // This assumes that only the host will have the End Game button available; otherwise, clients need to be able to send this message, too.
            {
                foreach (NetworkConnection connection in m_connections)
                    WriteByte(m_networkDriver, connection, m_localUser.ID, MsgType.EndInGame, 0);
            }
        }

        private void CheckIfAllUsersReady()
        {
            bool haveAllReadied = true;
            foreach (var user in m_localLobby.LobbyUsers)
            {
                if (user.Value.UserStatus != UserStatus.Ready)
                {   haveAllReadied = false;
                    break;
                }
            }
            if (haveAllReadied && m_localLobby.State == LobbyState.Lobby) // Need to notify both this client and all others that all players have readied.
            {
                Locator.Get.Messenger.OnReceiveMessage(MessageType.StartCountdown, null);
                foreach (NetworkConnection connection in m_connections)
                    WriteByte(m_networkDriver, connection, m_localUser.ID, MsgType.StartCountdown, 0);
            }
            else if (!haveAllReadied && m_localLobby.State == LobbyState.CountDown) // Someone cancelled during the countdown, so abort the countdown.
            {
                Locator.Get.Messenger.OnReceiveMessage(MessageType.CancelCountdown, null);
                foreach (NetworkConnection connection in m_connections)
                    WriteByte(m_networkDriver, connection, m_localUser.ID, MsgType.CancelCountdown, 0);
            }
        }

        /// <summary>
        /// In an actual game, after the countdown, there would be some step here where the host and all clients sync up on game state, load assets, etc.
        /// Here, we will instead just signal an "in game" state that can be ended by the host.
        /// </summary>
        public void SendInGameState()
        {
            Locator.Get.Messenger.OnReceiveMessage(MessageType.ConfirmInGameState, null);
            foreach (NetworkConnection connection in m_connections)
                WriteByte(m_networkDriver, connection, m_localUser.ID, MsgType.ConfirmInGame, 0);
        }

        /// <summary>
        /// Clean out destroyed connections, and accept all new ones.
        /// </summary>
        private void DoHeartbeat()
        {
            m_networkDriver.ScheduleUpdate().Complete();

            for (int c = m_connections.Count - 1; c >= 0; c--)
            {
                if (!m_connections[c].IsCreated)
                    m_connections.RemoveAt(c);
            }
            while (true)
            {
                var conn = m_networkDriver.Accept();
                if (!conn.IsCreated) // "Nothing more to accept" is signalled by returning an invalid connection from Accept.
                    break;
                m_connections.Add(conn);
                OnNewConnection(conn);
            }
        }
    }
}