Darker AO for the stone quary

[0ad.git] / source / network / NetServer.cpp

/* Copyright (C) 2021 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "precompiled.h"

#include "NetServer.h"

#include "NetClient.h"
#include "NetMessage.h"
#include "NetSession.h"
#include "NetServerTurnManager.h"
#include "NetStats.h"

#include "lib/external_libraries/enet.h"
#include "lib/types.h"
#include "network/StunClient.h"
#include "ps/CLogger.h"
#include "ps/ConfigDB.h"
#include "ps/GUID.h"
#include "ps/Hashing.h"
#include "ps/Profile.h"
#include "ps/Threading.h"
#include "scriptinterface/ScriptContext.h"
#include "scriptinterface/ScriptInterface.h"
#include "scriptinterface/JSON.h"
#include "simulation2/Simulation2.h"
#include "simulation2/system/TurnManager.h"

#if CONFIG2_MINIUPNPC
#include <miniupnpc/miniwget.h>
#include <miniupnpc/miniupnpc.h>
#include <miniupnpc/upnpcommands.h>
#include <miniupnpc/upnperrors.h>
#endif

#include <string>

/**
 * Number of peers to allocate for the enet host.
 * Limited by ENET_PROTOCOL_MAXIMUM_PEER_ID (4096).
 *
 * At most 8 players, 32 observers and 1 temporary connection to send the "server full" disconnect-reason.
 */
#define MAX_CLIENTS 41

#define DEFAULT_SERVER_NAME                     L"Unnamed Server"

constexpr int CHANNEL_COUNT = 1;
constexpr int FAILED_PASSWORD_TRIES_BEFORE_BAN = 3;

/**
 * enet_host_service timeout (msecs).
 * Smaller numbers may hurt performance; larger numbers will
 * hurt latency responding to messages from game thread.
 */
static const int HOST_SERVICE_TIMEOUT = 50;

/**
 * Once ping goes above turn length * command delay,
 * the game will start 'freezing' for other clients while we catch up.
 * Since commands are sent client -> server -> client, divide by 2.
 * (duplicated in NetServer.cpp to avoid having to fetch the constants in a header file)
 */
constexpr u32 NETWORK_BAD_PING = DEFAULT_TURN_LENGTH * COMMAND_DELAY_MP / 2;

CNetServer* g_NetServer = NULL;

static CStr DebugName(CNetServerSession* session)
{
        if (session == NULL)
                return "[unknown host]";
        if (session->GetGUID().empty())
                return "[unauthed host]";
        return "[" + session->GetGUID().substr(0, 8) + "...]";
}

/**
 * Async task for receiving the initial game state to be forwarded to another
 * client that is rejoining an in-progress network game.
 */
class CNetFileReceiveTask_ServerRejoin : public CNetFileReceiveTask
{
        NONCOPYABLE(CNetFileReceiveTask_ServerRejoin);
public:
        CNetFileReceiveTask_ServerRejoin(CNetServerWorker& server, u32 hostID)
                : m_Server(server), m_RejoinerHostID(hostID)
        {
        }

        virtual void OnComplete()
        {
                // We've received the game state from an existing player - now
                // we need to send it onwards to the newly rejoining player

                // Find the session corresponding to the rejoining host (if any)
                CNetServerSession* session = NULL;
                for (CNetServerSession* serverSession : m_Server.m_Sessions)
                {
                        if (serverSession->GetHostID() == m_RejoinerHostID)
                        {
                                session = serverSession;
                                break;
                        }
                }

                if (!session)
                {
                        LOGMESSAGE("Net server: rejoining client disconnected before we sent to it");
                        return;
                }

                // Store the received state file, and tell the client to start downloading it from us
                // TODO: this will get kind of confused if there's multiple clients downloading in parallel;
                // they'll race and get whichever happens to be the latest received by the server,
                // which should still work but isn't great
                m_Server.m_JoinSyncFile = m_Buffer;

                // Send the init attributes alongside - these should be correct since the game should be started.
                CJoinSyncStartMessage message;
                message.m_InitAttributes = Script::StringifyJSON(ScriptRequest(m_Server.GetScriptInterface()), &m_Server.m_InitAttributes);
                session->SendMessage(&message);
        }

private:
        CNetServerWorker& m_Server;
        u32 m_RejoinerHostID;
};

/*
 * XXX: We use some non-threadsafe functions from the worker thread.
 * See http://trac.wildfiregames.com/ticket/654
 */

CNetServerWorker::CNetServerWorker(bool useLobbyAuth, int autostartPlayers) :
        m_AutostartPlayers(autostartPlayers),
        m_LobbyAuth(useLobbyAuth),
        m_Shutdown(false),
        m_ScriptInterface(NULL),
        m_NextHostID(1), m_Host(NULL), m_ControllerGUID(), m_Stats(NULL),
        m_LastConnectionCheck(0)
{
        m_State = SERVER_STATE_UNCONNECTED;

        m_ServerTurnManager = NULL;

        m_ServerName = DEFAULT_SERVER_NAME;
}

CNetServerWorker::~CNetServerWorker()
{
        if (m_State != SERVER_STATE_UNCONNECTED)
        {
                // Tell the thread to shut down
                {
                        std::lock_guard<std::mutex> lock(m_WorkerMutex);
                        m_Shutdown = true;
                }

                // Wait for it to shut down cleanly
                m_WorkerThread.join();
        }

#if CONFIG2_MINIUPNPC
        if (m_UPnPThread.joinable())
                m_UPnPThread.detach();
#endif

        // Clean up resources

        delete m_Stats;

        for (CNetServerSession* session : m_Sessions)
        {
                session->DisconnectNow(NDR_SERVER_SHUTDOWN);
                delete session;
        }

        if (m_Host)
                enet_host_destroy(m_Host);

        delete m_ServerTurnManager;
}

void CNetServerWorker::SetPassword(const CStr& hashedPassword)
{
        m_Password = hashedPassword;
}


void CNetServerWorker::SetControllerSecret(const std::string& secret)
{
        m_ControllerSecret = secret;
}


bool CNetServerWorker::CheckPassword(const std::string& password, const std::string& salt) const
{
        return HashCryptographically(m_Password, salt) == password;
}


bool CNetServerWorker::SetupConnection(const u16 port)
{
        ENSURE(m_State == SERVER_STATE_UNCONNECTED);
        ENSURE(!m_Host);

        // Bind to default host
        ENetAddress addr;
        addr.host = ENET_HOST_ANY;
        addr.port = port;

        // Create ENet server
        m_Host = enet_host_create(&addr, MAX_CLIENTS, CHANNEL_COUNT, 0, 0);
        if (!m_Host)
        {
                LOGERROR("Net server: enet_host_create failed");
                return false;
        }

        m_Stats = new CNetStatsTable();
        if (CProfileViewer::IsInitialised())
                g_ProfileViewer.AddRootTable(m_Stats);

        m_State = SERVER_STATE_PREGAME;

        // Launch the worker thread
        m_WorkerThread = std::thread(Threading::HandleExceptions<RunThread>::Wrapper, this);

#if CONFIG2_MINIUPNPC
        // Launch the UPnP thread
        m_UPnPThread = std::thread(Threading::HandleExceptions<SetupUPnP>::Wrapper);
#endif

        return true;
}

#if CONFIG2_MINIUPNPC
void CNetServerWorker::SetupUPnP()
{
        debug_SetThreadName("UPnP");

        // Values we want to set.
        char psPort[6];
        sprintf_s(psPort, ARRAY_SIZE(psPort), "%d", PS_DEFAULT_PORT);
        const char* leaseDuration = "0"; // Indefinite/permanent lease duration.
        const char* description = "0AD Multiplayer";
        const char* protocall = "UDP";
        char internalIPAddress[64];
        char externalIPAddress[40];

        // Variables to hold the values that actually get set.
        char intClient[40];
        char intPort[6];
        char duration[16];

        // Intermediate variables.
        bool allocatedUrls = false;
        struct UPNPUrls urls;
        struct IGDdatas data;
        struct UPNPDev* devlist = NULL;

        // Make sure everything is properly freed.
        std::function<void()> freeUPnP = [&allocatedUrls, &urls, &devlist]()
        {
                if (allocatedUrls)
                        FreeUPNPUrls(&urls);
                freeUPNPDevlist(devlist);
                // IGDdatas does not need to be freed according to UPNP_GetIGDFromUrl
        };

        // Cached root descriptor URL.
        std::string rootDescURL;
        CFG_GET_VAL("network.upnprootdescurl", rootDescURL);
        if (!rootDescURL.empty())
                LOGMESSAGE("Net server: attempting to use cached root descriptor URL: %s", rootDescURL.c_str());

        int ret = 0;

        // Try a cached URL first
        if (!rootDescURL.empty() && UPNP_GetIGDFromUrl(rootDescURL.c_str(), &urls, &data, internalIPAddress, sizeof(internalIPAddress)))
        {
                LOGMESSAGE("Net server: using cached IGD = %s", urls.controlURL);
                ret = 1;
        }
        // No cached URL, or it did not respond. Try getting a valid UPnP device for 10 seconds.
#if defined(MINIUPNPC_API_VERSION) && MINIUPNPC_API_VERSION >= 14
        else if ((devlist = upnpDiscover(10000, 0, 0, 0, 0, 2, 0)) != NULL)
#else
        else if ((devlist = upnpDiscover(10000, 0, 0, 0, 0, 0)) != NULL)
#endif
        {
                ret = UPNP_GetValidIGD(devlist, &urls, &data, internalIPAddress, sizeof(internalIPAddress));
                allocatedUrls = ret != 0; // urls is allocated on non-zero return values
        }
        else
        {
                LOGMESSAGE("Net server: upnpDiscover failed and no working cached URL.");
                freeUPnP();
                return;
        }

        switch (ret)
        {
        case 0:
                LOGMESSAGE("Net server: No IGD found");
                break;
        case 1:
                LOGMESSAGE("Net server: found valid IGD = %s", urls.controlURL);
                break;
        case 2:
                LOGMESSAGE("Net server: found a valid, not connected IGD = %s, will try to continue anyway", urls.controlURL);
                break;
        case 3:
                LOGMESSAGE("Net server: found a UPnP device unrecognized as IGD = %s, will try to continue anyway", urls.controlURL);
                break;
        default:
                debug_warn(L"Unrecognized return value from UPNP_GetValidIGD");
        }

        // Try getting our external/internet facing IP. TODO: Display this on the game-setup page for conviniance.
        ret = UPNP_GetExternalIPAddress(urls.controlURL, data.first.servicetype, externalIPAddress);
        if (ret != UPNPCOMMAND_SUCCESS)
        {
                LOGMESSAGE("Net server: GetExternalIPAddress failed with code %d (%s)", ret, strupnperror(ret));
                freeUPnP();
                return;
        }
        LOGMESSAGE("Net server: ExternalIPAddress = %s", externalIPAddress);

        // Try to setup port forwarding.
        ret = UPNP_AddPortMapping(urls.controlURL, data.first.servicetype, psPort, psPort,
                                                        internalIPAddress, description, protocall, 0, leaseDuration);
        if (ret != UPNPCOMMAND_SUCCESS)
        {
                LOGMESSAGE("Net server: AddPortMapping(%s, %s, %s) failed with code %d (%s)",
                           psPort, psPort, internalIPAddress, ret, strupnperror(ret));
                freeUPnP();
                return;
        }

        // Check that the port was actually forwarded.
        ret = UPNP_GetSpecificPortMappingEntry(urls.controlURL,
                                                                         data.first.servicetype,
                                                                         psPort, protocall,
#if defined(MINIUPNPC_API_VERSION) && MINIUPNPC_API_VERSION >= 10
                                                                         NULL/*remoteHost*/,
#endif
                                                                         intClient, intPort, NULL/*desc*/,
                                                                         NULL/*enabled*/, duration);

        if (ret != UPNPCOMMAND_SUCCESS)
        {
                LOGMESSAGE("Net server: GetSpecificPortMappingEntry() failed with code %d (%s)", ret, strupnperror(ret));
                freeUPnP();
                return;
        }

        LOGMESSAGE("Net server: External %s:%s %s is redirected to internal %s:%s (duration=%s)",
                                   externalIPAddress, psPort, protocall, intClient, intPort, duration);

        // Cache root descriptor URL to try to avoid discovery next time.
        g_ConfigDB.SetValueString(CFG_USER, "network.upnprootdescurl", urls.controlURL);
        g_ConfigDB.WriteValueToFile(CFG_USER, "network.upnprootdescurl", urls.controlURL);
        LOGMESSAGE("Net server: cached UPnP root descriptor URL as %s", urls.controlURL);

        freeUPnP();
}
#endif // CONFIG2_MINIUPNPC

bool CNetServerWorker::SendMessage(ENetPeer* peer, const CNetMessage* message)
{
        ENSURE(m_Host);

        CNetServerSession* session = static_cast<CNetServerSession*>(peer->data);

        return CNetHost::SendMessage(message, peer, DebugName(session).c_str());
}

bool CNetServerWorker::Broadcast(const CNetMessage* message, const std::vector<NetServerSessionState>& targetStates)
{
        ENSURE(m_Host);

        bool ok = true;

        // TODO: this does lots of repeated message serialisation if we have lots
        // of remote peers; could do it more efficiently if that's a real problem

        for (CNetServerSession* session : m_Sessions)
                if (std::find(targetStates.begin(), targetStates.end(), static_cast<NetServerSessionState>(session->GetCurrState())) != targetStates.end() &&
                    !session->SendMessage(message))
                        ok = false;

        return ok;
}

void CNetServerWorker::RunThread(CNetServerWorker* data)
{
        debug_SetThreadName("NetServer");

        data->Run();
}

void CNetServerWorker::Run()
{
        // The script context uses the profiler and therefore the thread must be registered before the context is created
        g_Profiler2.RegisterCurrentThread("Net server");

        // We create a new ScriptContext for this network thread, with a single ScriptInterface.
        shared_ptr<ScriptContext> netServerContext = ScriptContext::CreateContext();
        m_ScriptInterface = new ScriptInterface("Engine", "Net server", netServerContext);
        m_InitAttributes.init(m_ScriptInterface->GetGeneralJSContext(), JS::UndefinedValue());

        while (true)
        {
                if (!RunStep())
                        break;

                // Implement autostart mode
                if (m_State == SERVER_STATE_PREGAME && (int)m_PlayerAssignments.size() == m_AutostartPlayers)
                        StartGame(Script::StringifyJSON(ScriptRequest(m_ScriptInterface), &m_InitAttributes));

                // Update profiler stats
                m_Stats->LatchHostState(m_Host);
        }

        // Clear roots before deleting their context
        m_SavedCommands.clear();

        SAFE_DELETE(m_ScriptInterface);
}

bool CNetServerWorker::RunStep()
{
        // Check for messages from the game thread.
        // (Do as little work as possible while the mutex is held open,
        // to avoid performance problems and deadlocks.)

        m_ScriptInterface->GetContext()->MaybeIncrementalGC(0.5f);

        ScriptRequest rq(m_ScriptInterface);

        std::vector<bool> newStartGame;
        std::vector<std::string> newGameAttributes;
        std::vector<std::pair<CStr, CStr>> newLobbyAuths;
        std::vector<u32> newTurnLength;

        {
                std::lock_guard<std::mutex> lock(m_WorkerMutex);

                if (m_Shutdown)
                        return false;

                newStartGame.swap(m_StartGameQueue);
                newGameAttributes.swap(m_InitAttributesQueue);
                newLobbyAuths.swap(m_LobbyAuthQueue);
                newTurnLength.swap(m_TurnLengthQueue);
        }

        if (!newGameAttributes.empty())
        {
                if (m_State != SERVER_STATE_UNCONNECTED && m_State != SERVER_STATE_PREGAME)
                        LOGERROR("NetServer: Init Attributes cannot be changed after the server starts loading.");
                else
                {
                        JS::RootedValue gameAttributesVal(rq.cx);
                        Script::ParseJSON(rq, newGameAttributes.back(), &gameAttributesVal);
                        m_InitAttributes = gameAttributesVal;
                }
        }

        if (!newTurnLength.empty())
                SetTurnLength(newTurnLength.back());

        while (!newLobbyAuths.empty())
        {
                const std::pair<CStr, CStr>& auth = newLobbyAuths.back();
                ProcessLobbyAuth(auth.first, auth.second);
                newLobbyAuths.pop_back();
        }

        // Perform file transfers
        for (CNetServerSession* session : m_Sessions)
                session->GetFileTransferer().Poll();

        CheckClientConnections();

        // Process network events:

        ENetEvent event;
        int status = enet_host_service(m_Host, &event, HOST_SERVICE_TIMEOUT);
        if (status < 0)
        {
                LOGERROR("CNetServerWorker: enet_host_service failed (%d)", status);
                // TODO: notify game that the server has shut down
                return false;
        }

        if (status == 0)
        {
                // Reached timeout with no events - try again
                return true;
        }

        // Process the event:

        switch (event.type)
        {
        case ENET_EVENT_TYPE_CONNECT:
        {
                // Report the client address
                char hostname[256] = "(error)";
                enet_address_get_host_ip(&event.peer->address, hostname, ARRAY_SIZE(hostname));
                LOGMESSAGE("Net server: Received connection from %s:%u", hostname, (unsigned int)event.peer->address.port);

                // Set up a session object for this peer

                CNetServerSession* session = new CNetServerSession(*this, event.peer);

                m_Sessions.push_back(session);

                SetupSession(session);

                ENSURE(event.peer->data == NULL);
                event.peer->data = session;

                HandleConnect(session);

                break;
        }

        case ENET_EVENT_TYPE_DISCONNECT:
        {
                // If there is an active session with this peer, then reset and delete it

                CNetServerSession* session = static_cast<CNetServerSession*>(event.peer->data);
                if (session)
                {
                        LOGMESSAGE("Net server: Disconnected %s", DebugName(session).c_str());

                        // Remove the session first, so we won't send player-update messages to it
                        // when updating the FSM
                        m_Sessions.erase(remove(m_Sessions.begin(), m_Sessions.end(), session), m_Sessions.end());

                        session->Update((uint)NMT_CONNECTION_LOST, NULL);

                        delete session;
                        event.peer->data = NULL;
                }

                if (m_State == SERVER_STATE_LOADING)
                        CheckGameLoadStatus(NULL);

                break;
        }

        case ENET_EVENT_TYPE_RECEIVE:
        {
                // If there is an active session with this peer, then process the message

                CNetServerSession* session = static_cast<CNetServerSession*>(event.peer->data);
                if (session)
                {
                        // Create message from raw data
                        CNetMessage* msg = CNetMessageFactory::CreateMessage(event.packet->data, event.packet->dataLength, GetScriptInterface());
                        if (msg)
                        {
                                LOGMESSAGE("Net server: Received message %s of size %lu from %s", msg->ToString().c_str(), (unsigned long)msg->GetSerializedLength(), DebugName(session).c_str());

                                HandleMessageReceive(msg, session);

                                delete msg;
                        }
                }

                // Done using the packet
                enet_packet_destroy(event.packet);

                break;
        }

        case ENET_EVENT_TYPE_NONE:
                break;
        }

        return true;
}

void CNetServerWorker::CheckClientConnections()
{
        // Send messages at most once per second
        std::time_t now = std::time(nullptr);
        if (now <= m_LastConnectionCheck)
                return;

        m_LastConnectionCheck = now;

        for (size_t i = 0; i < m_Sessions.size(); ++i)
        {
                u32 lastReceived = m_Sessions[i]->GetLastReceivedTime();
                u32 meanRTT = m_Sessions[i]->GetMeanRTT();

                CNetMessage* message = nullptr;

                // Report if we didn't hear from the client since few seconds
                if (lastReceived > NETWORK_WARNING_TIMEOUT)
                {
                        CClientTimeoutMessage* msg = new CClientTimeoutMessage();
                        msg->m_GUID = m_Sessions[i]->GetGUID();
                        msg->m_LastReceivedTime = lastReceived;
                        message = msg;
                }
                // Report if the client has bad ping
                else if (meanRTT > NETWORK_BAD_PING)
                {
                        CClientPerformanceMessage* msg = new CClientPerformanceMessage();
                        CClientPerformanceMessage::S_m_Clients client;
                        client.m_GUID = m_Sessions[i]->GetGUID();
                        client.m_MeanRTT = meanRTT;
                        msg->m_Clients.push_back(client);
                        message = msg;
                }

                // Send to all clients except the affected one
                // (since that will show the locally triggered warning instead).
                // Also send it to clients that finished the loading screen while
                // the game is still waiting for other clients to finish the loading screen.
                if (message)
                        for (size_t j = 0; j < m_Sessions.size(); ++j)
                        {
                                if (i != j && (
                                    (m_Sessions[j]->GetCurrState() == NSS_PREGAME && m_State == SERVER_STATE_PREGAME) ||
                                    m_Sessions[j]->GetCurrState() == NSS_INGAME))
                                {
                                        m_Sessions[j]->SendMessage(message);
                                }
                        }

                SAFE_DELETE(message);
        }
}

void CNetServerWorker::HandleMessageReceive(const CNetMessage* message, CNetServerSession* session)
{
        // Handle non-FSM messages first
        Status status = session->GetFileTransferer().HandleMessageReceive(*message);
        if (status != INFO::SKIPPED)
                return;

        if (message->GetType() == NMT_FILE_TRANSFER_REQUEST)
        {
                CFileTransferRequestMessage* reqMessage = (CFileTransferRequestMessage*)message;

                // Rejoining client got our JoinSyncStart after we received the state from
                // another client, and has now requested that we forward it to them

                ENSURE(!m_JoinSyncFile.empty());
                session->GetFileTransferer().StartResponse(reqMessage->m_RequestID, m_JoinSyncFile);

                return;
        }

        // Update FSM
        if (!session->Update(message->GetType(), (void*)message))
                LOGERROR("Net server: Error running FSM update (type=%d state=%d)", (int)message->GetType(), (int)session->GetCurrState());
}

void CNetServerWorker::SetupSession(CNetServerSession* session)
{
        void* context = session;

        // Set up transitions for session

        session->AddTransition(NSS_UNCONNECTED, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED);

        session->AddTransition(NSS_HANDSHAKE, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED);
        session->AddTransition(NSS_HANDSHAKE, (uint)NMT_CLIENT_HANDSHAKE, NSS_AUTHENTICATE, (void*)&OnClientHandshake, context);

        session->AddTransition(NSS_LOBBY_AUTHENTICATE, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED);
        session->AddTransition(NSS_LOBBY_AUTHENTICATE, (uint)NMT_AUTHENTICATE, NSS_PREGAME, (void*)&OnAuthenticate, context);

        session->AddTransition(NSS_AUTHENTICATE, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED);
        session->AddTransition(NSS_AUTHENTICATE, (uint)NMT_AUTHENTICATE, NSS_PREGAME, (void*)&OnAuthenticate, context);

        session->AddTransition(NSS_PREGAME, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED, (void*)&OnDisconnect, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_CHAT, NSS_PREGAME, (void*)&OnChat, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_READY, NSS_PREGAME, (void*)&OnReady, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_CLEAR_ALL_READY, NSS_PREGAME, (void*)&OnClearAllReady, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_GAME_SETUP, NSS_PREGAME, (void*)&OnGameSetup, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_ASSIGN_PLAYER, NSS_PREGAME, (void*)&OnAssignPlayer, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_KICKED, NSS_PREGAME, (void*)&OnKickPlayer, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_GAME_START, NSS_PREGAME, (void*)&OnGameStart, context);
        session->AddTransition(NSS_PREGAME, (uint)NMT_LOADED_GAME, NSS_INGAME, (void*)&OnLoadedGame, context);

        session->AddTransition(NSS_JOIN_SYNCING, (uint)NMT_KICKED, NSS_JOIN_SYNCING, (void*)&OnKickPlayer, context);
        session->AddTransition(NSS_JOIN_SYNCING, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED, (void*)&OnDisconnect, context);
        session->AddTransition(NSS_JOIN_SYNCING, (uint)NMT_LOADED_GAME, NSS_INGAME, (void*)&OnJoinSyncingLoadedGame, context);

        session->AddTransition(NSS_INGAME, (uint)NMT_REJOINED, NSS_INGAME, (void*)&OnRejoined, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_KICKED, NSS_INGAME, (void*)&OnKickPlayer, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_CLIENT_PAUSED, NSS_INGAME, (void*)&OnClientPaused, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_CONNECTION_LOST, NSS_UNCONNECTED, (void*)&OnDisconnect, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_CHAT, NSS_INGAME, (void*)&OnChat, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_SIMULATION_COMMAND, NSS_INGAME, (void*)&OnSimulationCommand, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_SYNC_CHECK, NSS_INGAME, (void*)&OnSyncCheck, context);
        session->AddTransition(NSS_INGAME, (uint)NMT_END_COMMAND_BATCH, NSS_INGAME, (void*)&OnEndCommandBatch, context);

        // Set first state
        session->SetFirstState(NSS_HANDSHAKE);
}

bool CNetServerWorker::HandleConnect(CNetServerSession* session)
{
        if (std::find(m_BannedIPs.begin(), m_BannedIPs.end(), session->GetIPAddress()) != m_BannedIPs.end())
        {
                session->Disconnect(NDR_BANNED);
                return false;
        }

        CSrvHandshakeMessage handshake;
        handshake.m_Magic = PS_PROTOCOL_MAGIC;
        handshake.m_ProtocolVersion = PS_PROTOCOL_VERSION;
        handshake.m_SoftwareVersion = PS_PROTOCOL_VERSION;
        return session->SendMessage(&handshake);
}

void CNetServerWorker::OnUserJoin(CNetServerSession* session)
{
        AddPlayer(session->GetGUID(), session->GetUserName());

        CPlayerAssignmentMessage assignMessage;
        ConstructPlayerAssignmentMessage(assignMessage);
        session->SendMessage(&assignMessage);
}

void CNetServerWorker::OnUserLeave(CNetServerSession* session)
{
        std::vector<CStr>::iterator pausing = std::find(m_PausingPlayers.begin(), m_PausingPlayers.end(), session->GetGUID());
        if (pausing != m_PausingPlayers.end())
                m_PausingPlayers.erase(pausing);

        RemovePlayer(session->GetGUID());

        if (m_ServerTurnManager && session->GetCurrState() != NSS_JOIN_SYNCING)
                m_ServerTurnManager->UninitialiseClient(session->GetHostID());

        // TODO: ought to switch the player controlled by that client
        // back to AI control, or something?
}

void CNetServerWorker::AddPlayer(const CStr& guid, const CStrW& name)
{
        // Find all player IDs in active use; we mustn't give them to a second player (excluding the unassigned ID: -1)
        std::set<i32> usedIDs;
        for (const std::pair<const CStr, PlayerAssignment>& p : m_PlayerAssignments)
                if (p.second.m_Enabled && p.second.m_PlayerID != -1)
                        usedIDs.insert(p.second.m_PlayerID);

        // If the player is rejoining after disconnecting, try to give them
        // back their old player ID

        i32 playerID = -1;

        // Try to match GUID first
        for (PlayerAssignmentMap::iterator it = m_PlayerAssignments.begin(); it != m_PlayerAssignments.end(); ++it)
        {
                if (!it->second.m_Enabled && it->first == guid && usedIDs.find(it->second.m_PlayerID) == usedIDs.end())
                {
                        playerID = it->second.m_PlayerID;
                        m_PlayerAssignments.erase(it); // delete the old mapping, since we've got a new one now
                        goto found;
                }
        }

        // Try to match username next
        for (PlayerAssignmentMap::iterator it = m_PlayerAssignments.begin(); it != m_PlayerAssignments.end(); ++it)
        {
                if (!it->second.m_Enabled && it->second.m_Name == name && usedIDs.find(it->second.m_PlayerID) == usedIDs.end())
                {
                        playerID = it->second.m_PlayerID;
                        m_PlayerAssignments.erase(it); // delete the old mapping, since we've got a new one now
                        goto found;
                }
        }

        // Otherwise leave the player ID as -1 (observer) and let gamesetup change it as needed.

found:
        PlayerAssignment assignment;
        assignment.m_Enabled = true;
        assignment.m_Name = name;
        assignment.m_PlayerID = playerID;
        assignment.m_Status = 0;
        m_PlayerAssignments[guid] = assignment;

        // Send the new assignments to all currently active players
        // (which does not include the one that's just joining)
        SendPlayerAssignments();
}

void CNetServerWorker::RemovePlayer(const CStr& guid)
{
        m_PlayerAssignments[guid].m_Enabled = false;

        SendPlayerAssignments();
}

void CNetServerWorker::ClearAllPlayerReady()
{
        for (std::pair<const CStr, PlayerAssignment>& p : m_PlayerAssignments)
                if (p.second.m_Status != 2)
                        p.second.m_Status = 0;

        SendPlayerAssignments();
}

void CNetServerWorker::KickPlayer(const CStrW& playerName, const bool ban)
{
        // Find the user with that name
        std::vector<CNetServerSession*>::iterator it = std::find_if(m_Sessions.begin(), m_Sessions.end(),
                [&](CNetServerSession* session) { return session->GetUserName() == playerName; });

        // and return if no one or the host has that name
        if (it == m_Sessions.end() || (*it)->GetGUID() == m_ControllerGUID)
                return;

        if (ban)
        {
                // Remember name
                if (std::find(m_BannedPlayers.begin(), m_BannedPlayers.end(), playerName) == m_BannedPlayers.end())
                        m_BannedPlayers.push_back(m_LobbyAuth ? CStrW(playerName.substr(0, playerName.find(L" ("))) : playerName);

                // Remember IP address
                u32 ipAddress = (*it)->GetIPAddress();
                if (std::find(m_BannedIPs.begin(), m_BannedIPs.end(), ipAddress) == m_BannedIPs.end())
                        m_BannedIPs.push_back(ipAddress);
        }

        // Disconnect that user
        (*it)->Disconnect(ban ? NDR_BANNED : NDR_KICKED);

        // Send message notifying other clients
        CKickedMessage kickedMessage;
        kickedMessage.m_Name = playerName;
        kickedMessage.m_Ban = ban;
        Broadcast(&kickedMessage, { NSS_PREGAME, NSS_JOIN_SYNCING, NSS_INGAME });
}

void CNetServerWorker::AssignPlayer(int playerID, const CStr& guid)
{
        // Remove anyone who's already assigned to this player
        for (std::pair<const CStr, PlayerAssignment>& p : m_PlayerAssignments)
        {
                if (p.second.m_PlayerID == playerID)
                        p.second.m_PlayerID = -1;
        }

        // Update this host's assignment if it exists
        if (m_PlayerAssignments.find(guid) != m_PlayerAssignments.end())
                m_PlayerAssignments[guid].m_PlayerID = playerID;

        SendPlayerAssignments();
}

void CNetServerWorker::ConstructPlayerAssignmentMessage(CPlayerAssignmentMessage& message)
{
        for (const std::pair<const CStr, PlayerAssignment>& p : m_PlayerAssignments)
        {
                if (!p.second.m_Enabled)
                        continue;

                CPlayerAssignmentMessage::S_m_Hosts h;
                h.m_GUID = p.first;
                h.m_Name = p.second.m_Name;
                h.m_PlayerID = p.second.m_PlayerID;
                h.m_Status = p.second.m_Status;
                message.m_Hosts.push_back(h);
        }
}

void CNetServerWorker::SendPlayerAssignments()
{
        CPlayerAssignmentMessage message;
        ConstructPlayerAssignmentMessage(message);
        Broadcast(&message, { NSS_PREGAME, NSS_JOIN_SYNCING, NSS_INGAME });
}

const ScriptInterface& CNetServerWorker::GetScriptInterface()
{
        return *m_ScriptInterface;
}

void CNetServerWorker::SetTurnLength(u32 msecs)
{
        if (m_ServerTurnManager)
                m_ServerTurnManager->SetTurnLength(msecs);
}

void CNetServerWorker::ProcessLobbyAuth(const CStr& name, const CStr& token)
{
        LOGMESSAGE("Net Server: Received lobby auth message from %s with %s", name, token);
        // Find the user with that guid
        std::vector<CNetServerSession*>::iterator it = std::find_if(m_Sessions.begin(), m_Sessions.end(),
                [&](CNetServerSession* session)
                { return session->GetGUID() == token; });

        if (it == m_Sessions.end())
                return;

        (*it)->SetUserName(name.FromUTF8());
        // Send an empty message to request the authentication message from the client
        // after its identity has been confirmed via the lobby
        CAuthenticateMessage emptyMessage;
        (*it)->SendMessage(&emptyMessage);
}

bool CNetServerWorker::OnClientHandshake(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_CLIENT_HANDSHAKE);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CCliHandshakeMessage* message = (CCliHandshakeMessage*)event->GetParamRef();
        if (message->m_ProtocolVersion != PS_PROTOCOL_VERSION)
        {
                session->Disconnect(NDR_INCORRECT_PROTOCOL_VERSION);
                return false;
        }

        CStr guid = ps_generate_guid();
        int count = 0;
        // Ensure unique GUID
        while(std::find_if(
                server.m_Sessions.begin(), server.m_Sessions.end(),
                [&guid] (const CNetServerSession* session)
                { return session->GetGUID() == guid; }) != server.m_Sessions.end())
        {
                if (++count > 100)
                {
                        session->Disconnect(NDR_GUID_FAILED);
                        return true;
                }
                guid = ps_generate_guid();
        }

        session->SetGUID(guid);

        CSrvHandshakeResponseMessage handshakeResponse;
        handshakeResponse.m_UseProtocolVersion = PS_PROTOCOL_VERSION;
        handshakeResponse.m_GUID = guid;
        handshakeResponse.m_Flags = 0;

        if (server.m_LobbyAuth)
        {
                handshakeResponse.m_Flags |= PS_NETWORK_FLAG_REQUIRE_LOBBYAUTH;
                session->SetNextState(NSS_LOBBY_AUTHENTICATE);
        }

        session->SendMessage(&handshakeResponse);

        return true;
}

bool CNetServerWorker::OnAuthenticate(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_AUTHENTICATE);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        // Prohibit joins while the game is loading
        if (server.m_State == SERVER_STATE_LOADING)
        {
                LOGMESSAGE("Refused connection while the game is loading");
                session->Disconnect(NDR_SERVER_LOADING);
                return true;
        }

        CAuthenticateMessage* message = (CAuthenticateMessage*)event->GetParamRef();
        CStrW username = SanitisePlayerName(message->m_Name);
        CStrW usernameWithoutRating(username.substr(0, username.find(L" (")));

        // Compare the lowercase names as specified by https://xmpp.org/extensions/xep-0029.html#sect-idm139493404168176
        // "[...] comparisons will be made in case-normalized canonical form."
        if (server.m_LobbyAuth && usernameWithoutRating.LowerCase() != session->GetUserName().LowerCase())
        {
                LOGERROR("Net server: lobby auth: %s tried joining as %s",
                        session->GetUserName().ToUTF8(),
                        usernameWithoutRating.ToUTF8());
                session->Disconnect(NDR_LOBBY_AUTH_FAILED);
                return true;
        }

        // Check the password before anything else.
        // NB: m_Name must match the client's salt, @see CNetClient::SetGamePassword
        if (!server.CheckPassword(message->m_Password, message->m_Name.ToUTF8()))
        {
                // Noisy logerror because players are not supposed to be able to get the IP,
                // so this might be someone targeting the host for some reason
                // (or TODO a dedicated server and we do want to log anyways)
                LOGERROR("Net server: user %s tried joining with the wrong password",
                                 session->GetUserName().ToUTF8());
                session->Disconnect(NDR_SERVER_REFUSED);
                return true;
        }

        // Either deduplicate or prohibit join if name is in use
        bool duplicatePlayernames = false;
        CFG_GET_VAL("network.duplicateplayernames", duplicatePlayernames);
        // If lobby authentication is enabled, the clients playername has already been registered.
        // There also can't be any duplicated names.
        if (!server.m_LobbyAuth && duplicatePlayernames)
                username = server.DeduplicatePlayerName(username);
        else
        {
                std::vector<CNetServerSession*>::iterator it = std::find_if(
                        server.m_Sessions.begin(), server.m_Sessions.end(),
                        [&username] (const CNetServerSession* session)
                        { return session->GetUserName() == username; });

                if (it != server.m_Sessions.end() && (*it) != session)
                {
                        session->Disconnect(NDR_PLAYERNAME_IN_USE);
                        return true;
                }
        }

        // Disconnect banned usernames
        if (std::find(server.m_BannedPlayers.begin(), server.m_BannedPlayers.end(), server.m_LobbyAuth ? usernameWithoutRating : username) != server.m_BannedPlayers.end())
        {
                session->Disconnect(NDR_BANNED);
                return true;
        }

        int maxObservers = 0;
        CFG_GET_VAL("network.observerlimit", maxObservers);

        bool isRejoining = false;
        bool serverFull = false;
        if (server.m_State == SERVER_STATE_PREGAME)
        {
                // Don't check for maxObservers in the gamesetup, as we don't know yet who will be assigned
                serverFull = server.m_Sessions.size() >= MAX_CLIENTS;
        }
        else
        {
                bool isObserver = true;
                int disconnectedPlayers = 0;
                int connectedPlayers = 0;
                // (TODO: if GUIDs were stable, we should use them instead)
                for (const std::pair<const CStr, PlayerAssignment>& p : server.m_PlayerAssignments)
                {
                        const PlayerAssignment& assignment = p.second;

                        if (!assignment.m_Enabled && assignment.m_Name == username)
                        {
                                isObserver = assignment.m_PlayerID == -1;
                                isRejoining = true;
                        }

                        if (assignment.m_PlayerID == -1)
                                continue;

                        if (assignment.m_Enabled)
                                ++connectedPlayers;
                        else
                                ++disconnectedPlayers;
                }

                // Optionally allow everyone or only buddies to join after the game has started
                if (!isRejoining)
                {
                        CStr observerLateJoin;
                        CFG_GET_VAL("network.lateobservers", observerLateJoin);

                        if (observerLateJoin == "everyone")
                        {
                                isRejoining = true;
                        }
                        else if (observerLateJoin == "buddies")
                        {
                                CStr buddies;
                                CFG_GET_VAL("lobby.buddies", buddies);
                                std::wstringstream buddiesStream(wstring_from_utf8(buddies));
                                CStrW buddy;
                                while (std::getline(buddiesStream, buddy, L','))
                                {
                                        if (buddy == usernameWithoutRating)
                                        {
                                                isRejoining = true;
                                                break;
                                        }
                                }
                        }
                }

                if (!isRejoining)
                {
                        LOGMESSAGE("Refused connection after game start from not-previously-known user \"%s\"", utf8_from_wstring(username));
                        session->Disconnect(NDR_SERVER_ALREADY_IN_GAME);
                        return true;
                }

                // Ensure all players will be able to rejoin
                serverFull = isObserver && (
                        (int) server.m_Sessions.size() - connectedPlayers > maxObservers ||
                        (int) server.m_Sessions.size() + disconnectedPlayers >= MAX_CLIENTS);
        }

        if (serverFull)
        {
                session->Disconnect(NDR_SERVER_FULL);
                return true;
        }

        u32 newHostID = server.m_NextHostID++;

        session->SetUserName(username);
        session->SetHostID(newHostID);

        CAuthenticateResultMessage authenticateResult;
        authenticateResult.m_Code = isRejoining ? ARC_OK_REJOINING : ARC_OK;
        authenticateResult.m_HostID = newHostID;
        authenticateResult.m_Message = L"Logged in";
        authenticateResult.m_IsController = 0;

        if (message->m_ControllerSecret == server.m_ControllerSecret)
        {
                if (server.m_ControllerGUID.empty())
                {
                        server.m_ControllerGUID = session->GetGUID();
                        authenticateResult.m_IsController = 1;
                }
                // TODO: we could probably handle having several controllers, or swapping?
        }

        session->SendMessage(&authenticateResult);

        server.OnUserJoin(session);

        if (isRejoining)
        {
                ENSURE(server.m_State != SERVER_STATE_UNCONNECTED && server.m_State != SERVER_STATE_PREGAME);

                // Request a copy of the current game state from an existing player,
                // so we can send it on to the new player

                // Assume session 0 is most likely the local player, so they're
                // the most efficient client to request a copy from
                CNetServerSession* sourceSession = server.m_Sessions.at(0);

                sourceSession->GetFileTransferer().StartTask(
                        shared_ptr<CNetFileReceiveTask>(new CNetFileReceiveTask_ServerRejoin(server, newHostID))
                );

                session->SetNextState(NSS_JOIN_SYNCING);
        }

        return true;
}
bool CNetServerWorker::OnSimulationCommand(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_SIMULATION_COMMAND);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CSimulationMessage* message = (CSimulationMessage*)event->GetParamRef();

        // Ignore messages sent by one player on behalf of another player
        // unless cheating is enabled
        bool cheatsEnabled = false;
        const ScriptInterface& scriptInterface = server.GetScriptInterface();
        ScriptRequest rq(scriptInterface);
        JS::RootedValue settings(rq.cx);
        Script::GetProperty(rq, server.m_InitAttributes, "settings", &settings);
        if (Script::HasProperty(rq, settings, "CheatsEnabled"))
                Script::GetProperty(rq, settings, "CheatsEnabled", cheatsEnabled);

        PlayerAssignmentMap::iterator it = server.m_PlayerAssignments.find(session->GetGUID());
        // When cheating is disabled, fail if the player the message claims to
        // represent does not exist or does not match the sender's player name
        if (!cheatsEnabled && (it == server.m_PlayerAssignments.end() || it->second.m_PlayerID != message->m_Player))
                return true;

        // Send it back to all clients that have finished
        // the loading screen (and the synchronization when rejoining)
        server.Broadcast(message, { NSS_INGAME });

        // Save all the received commands
        if (server.m_SavedCommands.size() < message->m_Turn + 1)
                server.m_SavedCommands.resize(message->m_Turn + 1);
        server.m_SavedCommands[message->m_Turn].push_back(*message);

        // TODO: we shouldn't send the message back to the client that first sent it
        return true;
}

bool CNetServerWorker::OnSyncCheck(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_SYNC_CHECK);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CSyncCheckMessage* message = (CSyncCheckMessage*)event->GetParamRef();

        server.m_ServerTurnManager->NotifyFinishedClientUpdate(*session, message->m_Turn, message->m_Hash);
        return true;
}

bool CNetServerWorker::OnEndCommandBatch(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_END_COMMAND_BATCH);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CEndCommandBatchMessage* message = (CEndCommandBatchMessage*)event->GetParamRef();

        // The turn-length field is ignored
        server.m_ServerTurnManager->NotifyFinishedClientCommands(*session, message->m_Turn);
        return true;
}

bool CNetServerWorker::OnChat(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_CHAT);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CChatMessage* message = (CChatMessage*)event->GetParamRef();

        message->m_GUID = session->GetGUID();

        server.Broadcast(message, { NSS_PREGAME, NSS_INGAME });

        return true;
}

bool CNetServerWorker::OnReady(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_READY);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        // Occurs if a client presses not-ready
        // in the very last moment before the hosts starts the game
        if (server.m_State == SERVER_STATE_LOADING)
                return true;

        CReadyMessage* message = (CReadyMessage*)event->GetParamRef();
        message->m_GUID = session->GetGUID();
        server.Broadcast(message, { NSS_PREGAME });

        server.m_PlayerAssignments[message->m_GUID].m_Status = message->m_Status;

        return true;
}

bool CNetServerWorker::OnClearAllReady(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_CLEAR_ALL_READY);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        if (session->GetGUID() == server.m_ControllerGUID)
                server.ClearAllPlayerReady();

        return true;
}

bool CNetServerWorker::OnGameSetup(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_GAME_SETUP);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        // Changing the settings after gamestart is not implemented and would cause an Out-of-sync error.
        // This happened when doubleclicking on the startgame button.
        if (server.m_State != SERVER_STATE_PREGAME)
                return true;

        // Only the controller is allowed to send game setup updates.
        // TODO: it would be good to allow other players to request changes to some settings,
        // e.g. their civilisation.
        // Possibly this should use another message, to enforce a single source of truth.
        if (session->GetGUID() == server.m_ControllerGUID)
        {
                CGameSetupMessage* message = (CGameSetupMessage*)event->GetParamRef();
                server.Broadcast(message, { NSS_PREGAME });
        }
        return true;
}

bool CNetServerWorker::OnAssignPlayer(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_ASSIGN_PLAYER);
        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        if (session->GetGUID() == server.m_ControllerGUID)
        {
                CAssignPlayerMessage* message = (CAssignPlayerMessage*)event->GetParamRef();
                server.AssignPlayer(message->m_PlayerID, message->m_GUID);
        }
        return true;
}

bool CNetServerWorker::OnGameStart(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_GAME_START);
        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        if (session->GetGUID() != server.m_ControllerGUID)
                return true;

        CGameStartMessage* message = (CGameStartMessage*)event->GetParamRef();
        server.StartGame(message->m_InitAttributes);
        return true;
}

bool CNetServerWorker::OnLoadedGame(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_LOADED_GAME);

        CNetServerSession* loadedSession = (CNetServerSession*)context;
        CNetServerWorker& server = loadedSession->GetServer();

        // We're in the loading state, so wait until every client has loaded
        // before starting the game
        ENSURE(server.m_State == SERVER_STATE_LOADING);
        if (server.CheckGameLoadStatus(loadedSession))
                return true;

        CClientsLoadingMessage message;
        // We always send all GUIDs of clients in the loading state
        // so that we don't have to bother about switching GUI pages
        for (CNetServerSession* session : server.m_Sessions)
                if (session->GetCurrState() != NSS_INGAME && loadedSession->GetGUID() != session->GetGUID())
                {
                        CClientsLoadingMessage::S_m_Clients client;
                        client.m_GUID = session->GetGUID();
                        message.m_Clients.push_back(client);
                }

        // Send to the client who has loaded the game but did not reach the NSS_INGAME state yet
        loadedSession->SendMessage(&message);
        server.Broadcast(&message, { NSS_INGAME });

        return true;
}

bool CNetServerWorker::OnJoinSyncingLoadedGame(void* context, CFsmEvent* event)
{
        // A client rejoining an in-progress game has now finished loading the
        // map and deserialized the initial state.
        // The simulation may have progressed since then, so send any subsequent
        // commands to them and set them as an active player so they can participate
        // in all future turns.
        //
        // (TODO: if it takes a long time for them to receive and execute all these
        // commands, the other players will get frozen for that time and may be unhappy;
        // we could try repeating this process a few times until the client converges
        // on the up-to-date state, before setting them as active.)

        ENSURE(event->GetType() == (uint)NMT_LOADED_GAME);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CLoadedGameMessage* message = (CLoadedGameMessage*)event->GetParamRef();

        u32 turn = message->m_CurrentTurn;
        u32 readyTurn = server.m_ServerTurnManager->GetReadyTurn();

        // Send them all commands received since their saved state,
        // and turn-ended messages for any turns that have already been processed
        for (size_t i = turn + 1; i < std::max(readyTurn+1, (u32)server.m_SavedCommands.size()); ++i)
        {
                if (i < server.m_SavedCommands.size())
                        for (size_t j = 0; j < server.m_SavedCommands[i].size(); ++j)
                                session->SendMessage(&server.m_SavedCommands[i][j]);

                if (i <= readyTurn)
                {
                        CEndCommandBatchMessage endMessage;
                        endMessage.m_Turn = i;
                        endMessage.m_TurnLength = server.m_ServerTurnManager->GetSavedTurnLength(i);
                        session->SendMessage(&endMessage);
                }
        }

        // Tell the turn manager to expect commands from this new client
        // Special case: the controller shouldn't be treated as an observer in any case.
        bool isObserver = server.m_PlayerAssignments[session->GetGUID()].m_PlayerID == -1 && server.m_ControllerGUID != session->GetGUID();
        server.m_ServerTurnManager->InitialiseClient(session->GetHostID(), readyTurn, isObserver);

        // Tell the client that everything has finished loading and it should start now
        CLoadedGameMessage loaded;
        loaded.m_CurrentTurn = readyTurn;
        session->SendMessage(&loaded);

        return true;
}

bool CNetServerWorker::OnRejoined(void* context, CFsmEvent* event)
{
        // A client has finished rejoining and the loading screen disappeared.
        ENSURE(event->GetType() == (uint)NMT_REJOINED);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        // Inform everyone of the client having rejoined
        CRejoinedMessage* message = (CRejoinedMessage*)event->GetParamRef();
        message->m_GUID = session->GetGUID();
        server.Broadcast(message, { NSS_INGAME });

        // Send all pausing players to the rejoined client.
        for (const CStr& guid : server.m_PausingPlayers)
        {
                CClientPausedMessage pausedMessage;
                pausedMessage.m_GUID = guid;
                pausedMessage.m_Pause = true;
                session->SendMessage(&pausedMessage);
        }

        return true;
}

bool CNetServerWorker::OnKickPlayer(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_KICKED);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        if (session->GetGUID() == server.m_ControllerGUID)
        {
                CKickedMessage* message = (CKickedMessage*)event->GetParamRef();
                server.KickPlayer(message->m_Name, message->m_Ban);
        }
        return true;
}

bool CNetServerWorker::OnDisconnect(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_CONNECTION_LOST);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        server.OnUserLeave(session);

        return true;
}

bool CNetServerWorker::OnClientPaused(void* context, CFsmEvent* event)
{
        ENSURE(event->GetType() == (uint)NMT_CLIENT_PAUSED);

        CNetServerSession* session = (CNetServerSession*)context;
        CNetServerWorker& server = session->GetServer();

        CClientPausedMessage* message = (CClientPausedMessage*)event->GetParamRef();

        message->m_GUID = session->GetGUID();

        // Update the list of pausing players.
        std::vector<CStr>::iterator player = std::find(server.m_PausingPlayers.begin(), server.m_PausingPlayers.end(), session->GetGUID());

        if (message->m_Pause)
        {
                if (player != server.m_PausingPlayers.end())
                        return true;

                server.m_PausingPlayers.push_back(session->GetGUID());
        }
        else
        {
                if (player == server.m_PausingPlayers.end())
                        return true;

                server.m_PausingPlayers.erase(player);
        }

        // Send messages to clients that are in game, and are not the client who paused.
        for (CNetServerSession* netSession : server.m_Sessions)
                if (netSession->GetCurrState() == NSS_INGAME && message->m_GUID != netSession->GetGUID())
                        netSession->SendMessage(message);

        return true;
}

bool CNetServerWorker::CheckGameLoadStatus(CNetServerSession* changedSession)
{
        for (const CNetServerSession* session : m_Sessions)
                if (session != changedSession && session->GetCurrState() != NSS_INGAME)
                        return false;

        // Inform clients that everyone has loaded the map and that the game can start
        CLoadedGameMessage loaded;
        loaded.m_CurrentTurn = 0;

        // Notice the changedSession is still in the NSS_PREGAME state
        Broadcast(&loaded, { NSS_PREGAME, NSS_INGAME });

        m_State = SERVER_STATE_INGAME;
        return true;
}

void CNetServerWorker::StartGame(const CStr& initAttribs)
{
        for (std::pair<const CStr, PlayerAssignment>& player : m_PlayerAssignments)
                if (player.second.m_Enabled && player.second.m_PlayerID != -1 && player.second.m_Status == 0)
                {
                        LOGERROR("Tried to start the game without player \"%s\" being ready!", utf8_from_wstring(player.second.m_Name).c_str());
                        return;
                }

        m_ServerTurnManager = new CNetServerTurnManager(*this);

        for (CNetServerSession* session : m_Sessions)
        {
                // Special case: the controller shouldn't be treated as an observer in any case.
                bool isObserver = m_PlayerAssignments[session->GetGUID()].m_PlayerID == -1 && m_ControllerGUID != session->GetGUID();
                m_ServerTurnManager->InitialiseClient(session->GetHostID(), 0, isObserver);
        }

        m_State = SERVER_STATE_LOADING;

        // Remove players and observers that are not present when the game starts
        for (PlayerAssignmentMap::iterator it = m_PlayerAssignments.begin(); it != m_PlayerAssignments.end();)
                if (it->second.m_Enabled)
                        ++it;
                else
                        it = m_PlayerAssignments.erase(it);

        SendPlayerAssignments();

        // Update init attributes. They should no longer change.
        Script::ParseJSON(ScriptRequest(m_ScriptInterface), initAttribs, &m_InitAttributes);

        CGameStartMessage gameStart;
        gameStart.m_InitAttributes = initAttribs;
        Broadcast(&gameStart, { NSS_PREGAME });
}

CStrW CNetServerWorker::SanitisePlayerName(const CStrW& original)
{
        const size_t MAX_LENGTH = 32;

        CStrW name = original;
        name.Replace(L"[", L"{"); // remove GUI tags
        name.Replace(L"]", L"}"); // remove for symmetry

        // Restrict the length
        if (name.length() > MAX_LENGTH)
                name = name.Left(MAX_LENGTH);

        // Don't allow surrounding whitespace
        name.Trim(PS_TRIM_BOTH);

        // Don't allow empty name
        if (name.empty())
                name = L"Anonymous";

        return name;
}

CStrW CNetServerWorker::DeduplicatePlayerName(const CStrW& original)
{
        CStrW name = original;

        // Try names "Foo", "Foo (2)", "Foo (3)", etc
        size_t id = 2;
        while (true)
        {
                bool unique = true;
                for (const CNetServerSession* session : m_Sessions)
                {
                        if (session->GetUserName() == name)
                        {
                                unique = false;
                                break;
                        }
                }

                if (unique)
                        return name;

                name = original + L" (" + CStrW::FromUInt(id++) + L")";
        }
}

void CNetServerWorker::SendHolePunchingMessage(const CStr& ipStr, u16 port)
{
        if (m_Host)
                StunClient::SendHolePunchingMessages(*m_Host, ipStr, port);
}




CNetServer::CNetServer(bool useLobbyAuth, int autostartPlayers) :
        m_Worker(new CNetServerWorker(useLobbyAuth, autostartPlayers)),
        m_LobbyAuth(useLobbyAuth), m_UseSTUN(false), m_PublicIp(""), m_PublicPort(20595), m_Password()
{
}

CNetServer::~CNetServer()
{
        delete m_Worker;
}

bool CNetServer::GetUseSTUN() const
{
        return m_UseSTUN;
}

bool CNetServer::UseLobbyAuth() const
{
        return m_LobbyAuth;
}

bool CNetServer::SetupConnection(const u16 port)
{
        return m_Worker->SetupConnection(port);
}

CStr CNetServer::GetPublicIp() const
{
        return m_PublicIp;
}

u16 CNetServer::GetPublicPort() const
{
        return m_PublicPort;
}

u16 CNetServer::GetLocalPort() const
{
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        if (!m_Worker->m_Host)
                return 0;
        return m_Worker->m_Host->address.port;
}

void CNetServer::SetConnectionData(const CStr& ip, const u16 port)
{
        m_PublicIp = ip;
        m_PublicPort = port;
        m_UseSTUN = false;
}

bool CNetServer::SetConnectionDataViaSTUN()
{
        m_UseSTUN = true;
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        if (!m_Worker->m_Host)
                return false;
        return StunClient::FindPublicIP(*m_Worker->m_Host, m_PublicIp, m_PublicPort);
}

bool CNetServer::CheckPasswordAndIncrement(const std::string& username, const std::string& password, const std::string& salt)
{
        std::unordered_map<std::string, int>::iterator it = m_FailedAttempts.find(username);
        if (m_Worker->CheckPassword(password, salt))
        {
                if (it != m_FailedAttempts.end())
                        it->second = 0;
                return true;
        }
        if (it == m_FailedAttempts.end())
                m_FailedAttempts.emplace(username, 1);
        else
                it->second++;
        return false;
}

bool CNetServer::IsBanned(const std::string& username) const
{
        std::unordered_map<std::string, int>::const_iterator it = m_FailedAttempts.find(username);
        return it != m_FailedAttempts.end() && it->second >= FAILED_PASSWORD_TRIES_BEFORE_BAN;
}

void CNetServer::SetPassword(const CStr& password)
{
        m_Password = password;
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->SetPassword(password);
}

void CNetServer::SetControllerSecret(const std::string& secret)
{
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->SetControllerSecret(secret);
}

void CNetServer::StartGame()
{
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->m_StartGameQueue.push_back(true);
}

void CNetServer::UpdateInitAttributes(JS::MutableHandleValue attrs, const ScriptRequest& rq)
{
        // Pass the attributes as JSON, since that's the easiest safe
        // cross-thread way of passing script data
        std::string attrsJSON = Script::StringifyJSON(rq, attrs, false);

        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->m_InitAttributesQueue.push_back(attrsJSON);
}

void CNetServer::OnLobbyAuth(const CStr& name, const CStr& token)
{
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->m_LobbyAuthQueue.push_back(std::make_pair(name, token));
}

void CNetServer::SetTurnLength(u32 msecs)
{
        std::lock_guard<std::mutex> lock(m_Worker->m_WorkerMutex);
        m_Worker->m_TurnLengthQueue.push_back(msecs);
}

void CNetServer::SendHolePunchingMessage(const CStr& ip, u16 port)
{
        m_Worker->SendHolePunchingMessage(ip, port);
}