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

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

        /// <summary>
        /// When a new client connects, they need to be given all up-to-date info.
        /// </summary>
        protected override void ProcessNetworkEventAdditional(DataStreamReader strm, NetworkEvent.Type cmd)
        {
            if (cmd == NetworkEvent.Type.Connect)
            {

            }
        }

        protected override void ProcessNetworkEventDataAdditional(NetworkConnection conn, DataStreamReader strm, MsgType msgType, string id)
        {
            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);
                }
            }

            // Note that the strm contents might have already been consumed, depending on the msgType.
            if (msgType == MsgType.ReadyState)
            {
                // TODO: Check if all players have readied.
            }
        }

        /// <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 con = m_networkDriver.Accept();
                if (!con.IsCreated) // "Nothing more to accept" is signalled by returning an invalid connection from Accept.
                    break;
                m_connections.Add(con);
            }
        }
    }
}