network_client.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "../stdafx.h"
#include "network_gui.h"
#include "../saveload/saveload.h"
#include "../saveload/saveload_filter.h"
#include "../command_func.h"
#include "../console_func.h"
#include "../strings_func.h"
#include "../window_func.h"
#include "../company_func.h"
#include "../company_base.h"
#include "../company_gui.h"
#include "../company_cmd.h"
#include "../core/random_func.hpp"
#include "../timer/timer_game_tick.h"
#include "../timer/timer_game_calendar.h"
#include "../gfx_func.h"
#include "../error.h"
#include "../rev.h"
#include "network.h"
#include "network_base.h"
#include "network_client.h"
#include "network_gamelist.h"
#include "../core/backup_type.hpp"
#include "../thread.h"
#include "../social_integration.h"
 
#include "table/strings.h"
 
#include "../safeguards.h"
 
/* This file handles all the client-commands */
 
struct PacketReader : LoadFilter {
  static const size_t CHUNK = 32 * 1024;  
 
  std::vector<uint8_t *> blocks;             
  uint8_t *buf;                              
  uint8_t *bufe;                             
  uint8_t **block;                           
  size_t written_bytes;                   
  size_t read_bytes;                      
 
  PacketReader() : LoadFilter(nullptr), buf(nullptr), bufe(nullptr), block(nullptr), written_bytes(0), read_bytes(0)
  {
  }
 
  ~PacketReader() override
  {
    for (auto p : this->blocks) {
      free(p);
    }
  }
 
  static inline ssize_t TransferOutMemCopy(PacketReader *destination, const char *source, size_t amount)
  {
    memcpy(destination->buf, source, amount);
    destination->buf += amount;
    destination->written_bytes += amount;
    return amount;
  }
 
  void AddPacket(Packet &p)
  {
    assert(this->read_bytes == 0);
    p.TransferOutWithLimit(TransferOutMemCopy, this->bufe - this->buf, this);
 
    /* Did everything fit in the current chunk, then we're done. */
    if (p.RemainingBytesToTransfer() == 0) return;
 
    /* Allocate a new chunk and add the remaining data. */
    this->blocks.push_back(this->buf = CallocT<uint8_t>(CHUNK));
    this->bufe = this->buf + CHUNK;
 
    p.TransferOutWithLimit(TransferOutMemCopy, this->bufe - this->buf, this);
  }
 
  size_t Read(uint8_t *rbuf, size_t size) override
  {
    /* Limit the amount to read to whatever we still have. */
    size_t ret_size = size = std::min(this->written_bytes - this->read_bytes, size);
    this->read_bytes += ret_size;
    const uint8_t *rbufe = rbuf + ret_size;
 
    while (rbuf != rbufe) {
      if (this->buf == this->bufe) {
        this->buf = *this->block++;
        this->bufe = this->buf + CHUNK;
      }
 
      size_t to_write = std::min(this->bufe - this->buf, rbufe - rbuf);
      memcpy(rbuf, this->buf, to_write);
      rbuf += to_write;
      this->buf += to_write;
    }
 
    return ret_size;
  }
 
  void Reset() override
  {
    this->read_bytes = 0;
 
    this->block = this->blocks.data();
    this->buf   = *this->block++;
    this->bufe  = this->buf + CHUNK;
  }
};
 
 
void ClientNetworkEmergencySave()
{
  static FiosNumberedSaveName _netsave_ctr("netsave");
  DoAutoOrNetsave(_netsave_ctr);
}
 
 
ClientNetworkGameSocketHandler::ClientNetworkGameSocketHandler(SOCKET s, const std::string &connection_string) : NetworkGameSocketHandler(s), connection_string(connection_string), savegame(nullptr), status(STATUS_INACTIVE)
{
  assert(ClientNetworkGameSocketHandler::my_client == nullptr);
  ClientNetworkGameSocketHandler::my_client = this;
}
 
ClientNetworkGameSocketHandler::~ClientNetworkGameSocketHandler()
{
  assert(ClientNetworkGameSocketHandler::my_client == this);
  ClientNetworkGameSocketHandler::my_client = nullptr;
 
  delete this->GetInfo();
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::CloseConnection(NetworkRecvStatus status)
{
  assert(status != NETWORK_RECV_STATUS_OKAY);
  if (this->IsPendingDeletion()) return status;
 
  assert(this->sock != INVALID_SOCKET);
 
  if (!this->HasClientQuit()) {
    Debug(net, 3, "Closed client connection {}", this->client_id);
 
    this->SendPackets(true);
 
    /* Wait a number of ticks so our leave message can reach the server.
     * This is especially needed for Windows servers as they seem to get
     * the "socket is closed" message before receiving our leave message,
     * which would trigger the server to close the connection as well. */
    CSleep(3 * MILLISECONDS_PER_TICK);
  }
 
  this->DeferDeletion();
 
  return status;
}
 
void ClientNetworkGameSocketHandler::ClientError(NetworkRecvStatus res)
{
  if (this->IsPendingDeletion()) return;
 
  /* First, send a CLIENT_ERROR to the server, so it knows we are
   *  disconnected (and why!) */
  NetworkErrorCode errorno;
 
  /* We just want to close the connection.. */
  if (res == NETWORK_RECV_STATUS_CLOSE_QUERY) {
    this->NetworkSocketHandler::MarkClosed();
    this->CloseConnection(res);
    _networking = false;
 
    CloseWindowById(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
    return;
  }
 
  switch (res) {
    case NETWORK_RECV_STATUS_DESYNC:          errorno = NETWORK_ERROR_DESYNC; break;
    case NETWORK_RECV_STATUS_SAVEGAME:        errorno = NETWORK_ERROR_SAVEGAME_FAILED; break;
    case NETWORK_RECV_STATUS_NEWGRF_MISMATCH: errorno = NETWORK_ERROR_NEWGRF_MISMATCH; break;
    default:                                  errorno = NETWORK_ERROR_GENERAL; break;
  }
 
  if (res == NETWORK_RECV_STATUS_SERVER_ERROR || res == NETWORK_RECV_STATUS_SERVER_FULL ||
      res == NETWORK_RECV_STATUS_SERVER_BANNED) {
    /* This means the server closed the connection. Emergency save is
     * already created if this was appropriate during handling of the
     * disconnect. */
    this->CloseConnection(res);
  } else {
    /* This means we as client made a boo-boo. */
    SendError(errorno);
 
    /* Close connection before we make an emergency save, as the save can
     * take a bit of time; better that the server doesn't stall while we
     * are doing the save, and already disconnects us. */
    this->CloseConnection(res);
    ClientNetworkEmergencySave();
  }
 
  CloseWindowById(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  if (_game_mode != GM_MENU) _switch_mode = SM_MENU;
  _networking = false;
}
 
 
/* static */ bool ClientNetworkGameSocketHandler::Receive()
{
  if (my_client->CanSendReceive()) {
    NetworkRecvStatus res = my_client->ReceivePackets();
    if (res != NETWORK_RECV_STATUS_OKAY) {
      /* The client made an error of which we can not recover.
       * Close the connection and drop back to the main menu. */
      my_client->ClientError(res);
      return false;
    }
  }
  return _networking;
}
 
/* static */ void ClientNetworkGameSocketHandler::Send()
{
  my_client->SendPackets();
  if (my_client != nullptr) my_client->CheckConnection();
}
 
/* static */ bool ClientNetworkGameSocketHandler::GameLoop()
{
  _frame_counter++;
 
  NetworkExecuteLocalCommandQueue();
 
  StateGameLoop();
 
  /* Check if we are in sync! */
  if (_sync_frame != 0) {
    if (_sync_frame == _frame_counter) {
#ifdef NETWORK_SEND_DOUBLE_SEED
      if (_sync_seed_1 != _random.state[0] || _sync_seed_2 != _random.state[1]) {
#else
      if (_sync_seed_1 != _random.state[0]) {
#endif
        ShowNetworkError(STR_NETWORK_ERROR_DESYNC);
        Debug(desync, 1, "sync_err: {:08x}; {:02x}", TimerGameEconomy::date, TimerGameEconomy::date_fract);
        Debug(net, 0, "Sync error detected");
        my_client->ClientError(NETWORK_RECV_STATUS_DESYNC);
        return false;
      }
 
      /* If this is the first time we have a sync-frame, we
       *   need to let the server know that we are ready and at the same
       *   frame as it is.. so we can start playing! */
      if (_network_first_time) {
        _network_first_time = false;
        SendAck();
      }
 
      _sync_frame = 0;
    } else if (_sync_frame < _frame_counter) {
      Debug(net, 1, "Missed frame for sync-test: {} / {}", _sync_frame, _frame_counter);
      _sync_frame = 0;
    }
  }
 
  return true;
}
 
 
ClientNetworkGameSocketHandler * ClientNetworkGameSocketHandler::my_client = nullptr;
 
static uint32_t last_ack_frame;
 
static uint8_t _network_server_max_companies;
std::string _network_server_name;
 
NetworkJoinInfo _network_join;
 
/***********
 * Sending functions
 ************/
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendJoin()
{
  Debug(net, 9, "Client::SendJoin()");
 
  Debug(net, 9, "Client::status = JOIN");
  my_client->status = STATUS_JOIN;
  Debug(net, 9, "Client::join_status = AUTHORIZING");
  _network_join_status = NETWORK_JOIN_STATUS_AUTHORIZING;
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_JOIN);
  p->Send_string(GetNetworkRevisionString());
  p->Send_uint32(_openttd_newgrf_version);
  my_client->SendPacket(std::move(p));
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendIdentify()
{
  Debug(net, 9, "Client::SendIdentify()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_IDENTIFY);
  p->Send_string(_settings_client.network.client_name); // Client name
  p->Send_uint8(_network_join.company); // PlayAs
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendNewGRFsOk()
{
  Debug(net, 9, "Client::SendNewGRFsOk()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_NEWGRFS_CHECKED);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendAuthResponse()
{
  Debug(net, 9, "Client::SendAuthResponse()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_AUTH_RESPONSE);
  my_client->authentication_handler->SendResponse(*p);
  my_client->SendPacket(std::move(p));
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendGetMap()
{
  Debug(net, 9, "Client::SendGetMap()");
 
  Debug(net, 9, "Client::status = MAP_WAIT");
  my_client->status = STATUS_MAP_WAIT;
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_GETMAP);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendMapOk()
{
  Debug(net, 9, "Client::SendMapOk()");
 
  Debug(net, 9, "Client::status = ACTIVE");
  my_client->status = STATUS_ACTIVE;
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_MAP_OK);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendAck()
{
  Debug(net, 9, "Client::SendAck()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_ACK);
 
  p->Send_uint32(_frame_counter);
  p->Send_uint8 (my_client->token);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendCommand(const CommandPacket &cp)
{
  Debug(net, 9, "Client::SendCommand(): cmd={}", cp.cmd);
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_COMMAND);
  my_client->NetworkGameSocketHandler::SendCommand(*p, cp);
 
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendChat(NetworkAction action, DestType type, int dest, const std::string &msg, int64_t data)
{
  Debug(net, 9, "Client::SendChat(): action={}, type={}, dest={}", action, type, dest);
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_CHAT);
 
  p->Send_uint8 (action);
  p->Send_uint8 (type);
  p->Send_uint32(dest);
  p->Send_string(msg);
  p->Send_uint64(data);
 
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendError(NetworkErrorCode errorno)
{
  Debug(net, 9, "Client::SendError(): errorno={}", errorno);
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_ERROR);
 
  p->Send_uint8(errorno);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendSetName(const std::string &name)
{
  Debug(net, 9, "Client::SendSetName()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_SET_NAME);
 
  p->Send_string(name);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendQuit()
{
  Debug(net, 9, "Client::SendQuit()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_QUIT);
 
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendRCon(const std::string &pass, const std::string &command)
{
  Debug(net, 9, "Client::SendRCon()");
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_RCON);
  p->Send_string(pass);
  p->Send_string(command);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::SendMove(CompanyID company)
{
  Debug(net, 9, "Client::SendMove(): company={}", company);
 
  auto p = std::make_unique<Packet>(my_client, PACKET_CLIENT_MOVE);
  p->Send_uint8(company);
  my_client->SendPacket(std::move(p));
  return NETWORK_RECV_STATUS_OKAY;
}
 
bool ClientNetworkGameSocketHandler::IsConnected()
{
  return my_client != nullptr && my_client->status == STATUS_ACTIVE;
}
 
 
/***********
 * Receiving functions
 ************/
 
extern bool SafeLoad(const std::string &filename, SaveLoadOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, std::shared_ptr<struct LoadFilter> lf);
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_FULL(Packet &)
{
  Debug(net, 9, "Client::Receive_SERVER_FULL()");
 
  /* We try to join a server which is full */
  ShowErrorMessage(STR_NETWORK_ERROR_SERVER_FULL, INVALID_STRING_ID, WL_CRITICAL);
 
  return NETWORK_RECV_STATUS_SERVER_FULL;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_BANNED(Packet &)
{
  Debug(net, 9, "Client::Receive_SERVER_BANNED()");
 
  /* We try to join a server where we are banned */
  ShowErrorMessage(STR_NETWORK_ERROR_SERVER_BANNED, INVALID_STRING_ID, WL_CRITICAL);
 
  return NETWORK_RECV_STATUS_SERVER_BANNED;
}
 
/* This packet contains info about the client (playas and name)
 *  as client we save this in NetworkClientInfo, linked via 'client_id'
 *  which is always an unique number on a server. */
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_CLIENT_INFO(Packet &p)
{
  NetworkClientInfo *ci;
  ClientID client_id = (ClientID)p.Recv_uint32();
  CompanyID playas = (CompanyID)p.Recv_uint8();
 
  Debug(net, 9, "Client::Receive_SERVER_CLIENT_INFO(): client_id={}, playas={}", client_id, playas);
 
  std::string name = p.Recv_string(NETWORK_NAME_LENGTH);
  std::string public_key = p.Recv_string(NETWORK_PUBLIC_KEY_LENGTH);
 
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  if (this->HasClientQuit()) return NETWORK_RECV_STATUS_CLIENT_QUIT;
  /* The server validates the name when receiving it from clients, so when it is wrong
   * here something went really wrong. In the best case the packet got malformed on its
   * way too us, in the worst case the server is broken or compromised. */
  if (!NetworkIsValidClientName(name)) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  ci = NetworkClientInfo::GetByClientID(client_id);
  if (ci != nullptr) {
    if (playas == ci->client_playas && name.compare(ci->client_name) != 0) {
      /* Client name changed, display the change */
      NetworkTextMessage(NETWORK_ACTION_NAME_CHANGE, CC_DEFAULT, false, ci->client_name, name);
    } else if (playas != ci->client_playas) {
      /* The client changed from client-player..
       * Do not display that for now */
    }
 
    /* Make sure we're in the company the server tells us to be in,
     * for the rare case that we get moved while joining. */
    if (client_id == _network_own_client_id) SetLocalCompany(!Company::IsValidID(playas) ? COMPANY_SPECTATOR : playas);
 
    ci->client_playas = playas;
    ci->client_name = name;
    ci->public_key = public_key;
 
    InvalidateWindowData(WC_CLIENT_LIST, 0);
 
    return NETWORK_RECV_STATUS_OKAY;
  }
 
  /* There are at most as many ClientInfo as ClientSocket objects in a
   * server. Having more info than a server can have means something
   * has gone wrong somewhere, i.e. the server has more info than it
   * has actual clients. That means the server is feeding us an invalid
   * state. So, bail out! This server is broken. */
  if (!NetworkClientInfo::CanAllocateItem()) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  /* We don't have this client_id yet, find an empty client_id, and put the data there */
  ci = new NetworkClientInfo(client_id);
  ci->client_playas = playas;
  if (client_id == _network_own_client_id) this->SetInfo(ci);
 
  ci->client_name = name;
  ci->public_key = public_key;
 
  InvalidateWindowData(WC_CLIENT_LIST, 0);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_ERROR(Packet &p)
{
  static const StringID network_error_strings[] = {
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_GENERAL
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_DESYNC
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_SAVEGAME_FAILED
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_CONNECTION_LOST
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_ILLEGAL_PACKET
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_NEWGRF_MISMATCH
    STR_NETWORK_ERROR_SERVER_ERROR,        // NETWORK_ERROR_NOT_AUTHORIZED
    STR_NETWORK_ERROR_SERVER_ERROR,        // NETWORK_ERROR_NOT_EXPECTED
    STR_NETWORK_ERROR_WRONG_REVISION,      // NETWORK_ERROR_WRONG_REVISION
    STR_NETWORK_ERROR_LOSTCONNECTION,      // NETWORK_ERROR_NAME_IN_USE
    STR_NETWORK_ERROR_WRONG_PASSWORD,      // NETWORK_ERROR_WRONG_PASSWORD
    STR_NETWORK_ERROR_SERVER_ERROR,        // NETWORK_ERROR_COMPANY_MISMATCH
    STR_NETWORK_ERROR_KICKED,              // NETWORK_ERROR_KICKED
    STR_NETWORK_ERROR_CHEATER,             // NETWORK_ERROR_CHEATER
    STR_NETWORK_ERROR_SERVER_FULL,         // NETWORK_ERROR_FULL
    STR_NETWORK_ERROR_TOO_MANY_COMMANDS,   // NETWORK_ERROR_TOO_MANY_COMMANDS
    STR_NETWORK_ERROR_TIMEOUT_PASSWORD,    // NETWORK_ERROR_TIMEOUT_PASSWORD
    STR_NETWORK_ERROR_TIMEOUT_COMPUTER,    // NETWORK_ERROR_TIMEOUT_COMPUTER
    STR_NETWORK_ERROR_TIMEOUT_MAP,         // NETWORK_ERROR_TIMEOUT_MAP
    STR_NETWORK_ERROR_TIMEOUT_JOIN,        // NETWORK_ERROR_TIMEOUT_JOIN
    STR_NETWORK_ERROR_INVALID_CLIENT_NAME, // NETWORK_ERROR_INVALID_CLIENT_NAME
    STR_NETWORK_ERROR_NOT_ON_ALLOW_LIST,   // NETWORK_ERROR_NOT_ON_ALLOW_LIST
    STR_NETWORK_ERROR_SERVER_ERROR,        // NETWORK_ERROR_NO_AUTHENTICATION_METHOD_AVAILABLE
  };
  static_assert(lengthof(network_error_strings) == NETWORK_ERROR_END);
 
  NetworkErrorCode error = (NetworkErrorCode)p.Recv_uint8();
 
  Debug(net, 9, "Client::Receive_SERVER_ERROR(): error={}", error);
 
  StringID err = STR_NETWORK_ERROR_LOSTCONNECTION;
  if (error < (ptrdiff_t)lengthof(network_error_strings)) err = network_error_strings[error];
  /* In case of kicking a client, we assume there is a kick message in the packet if we can read one byte */
  if (error == NETWORK_ERROR_KICKED && p.CanReadFromPacket(1)) {
    SetDParamStr(0, p.Recv_string(NETWORK_CHAT_LENGTH));
    ShowErrorMessage(err, STR_NETWORK_ERROR_KICK_MESSAGE, WL_CRITICAL);
  } else {
    ShowErrorMessage(err, INVALID_STRING_ID, WL_CRITICAL);
  }
 
  /* Perform an emergency save if we had already entered the game */
  if (this->status == STATUS_ACTIVE) ClientNetworkEmergencySave();
 
  return NETWORK_RECV_STATUS_SERVER_ERROR;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_CHECK_NEWGRFS(Packet &p)
{
  if (this->status != STATUS_ENCRYPTED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  uint grf_count = p.Recv_uint8();
  NetworkRecvStatus ret = NETWORK_RECV_STATUS_OKAY;
 
  Debug(net, 9, "Client::Receive_SERVER_CHECK_NEWGRFS(): grf_count={}", grf_count);
 
  /* Check all GRFs */
  for (; grf_count > 0; grf_count--) {
    GRFIdentifier c;
    DeserializeGRFIdentifier(p, c);
 
    /* Check whether we know this GRF */
    const GRFConfig *f = FindGRFConfig(c.grfid, FGCM_EXACT, &c.md5sum);
    if (f == nullptr) {
      /* We do not know this GRF, bail out of initialization */
      Debug(grf, 0, "NewGRF {:08X} not found; checksum {}", BSWAP32(c.grfid), FormatArrayAsHex(c.md5sum));
      ret = NETWORK_RECV_STATUS_NEWGRF_MISMATCH;
    }
  }
 
  if (ret == NETWORK_RECV_STATUS_OKAY) {
    /* Start receiving the map */
    return SendNewGRFsOk();
  }
 
  /* NewGRF mismatch, bail out */
  ShowErrorMessage(STR_NETWORK_ERROR_NEWGRF_MISMATCH, INVALID_STRING_ID, WL_CRITICAL);
  return ret;
}
 
class ClientGamePasswordRequestHandler : public NetworkAuthenticationPasswordRequestHandler {
  virtual void SendResponse() override { MyClient::SendAuthResponse(); }
  virtual void AskUserForPassword(std::shared_ptr<NetworkAuthenticationPasswordRequest> request) override
  {
    if (!_network_join.server_password.empty()) {
      request->Reply(_network_join.server_password);
    } else {
      ShowNetworkNeedPassword(request);
    }
  }
};
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_AUTH_REQUEST(Packet &p)
{
  if (this->status != STATUS_JOIN && this->status != STATUS_AUTH_GAME) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  Debug(net, 9, "Client::status = AUTH_GAME");
  this->status = STATUS_AUTH_GAME;
 
  Debug(net, 9, "Client::Receive_SERVER_AUTH_REQUEST()");
 
  if (this->authentication_handler == nullptr) {
    this->authentication_handler = NetworkAuthenticationClientHandler::Create(std::make_shared<ClientGamePasswordRequestHandler>(),
        _settings_client.network.client_secret_key, _settings_client.network.client_public_key);
  }
  switch (this->authentication_handler->ReceiveRequest(p)) {
    case NetworkAuthenticationClientHandler::READY_FOR_RESPONSE:
      return SendAuthResponse();
 
    case NetworkAuthenticationClientHandler::AWAIT_USER_INPUT:
      return NETWORK_RECV_STATUS_OKAY;
 
    case NetworkAuthenticationClientHandler::INVALID:
    default:
      return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  }
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_ENABLE_ENCRYPTION(Packet &p)
{
  if (this->status != STATUS_AUTH_GAME || this->authentication_handler == nullptr) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  Debug(net, 9, "Client::Receive_SERVER_ENABLE_ENCRYPTION()");
 
  if (!this->authentication_handler->ReceiveEnableEncryption(p)) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  this->receive_encryption_handler = this->authentication_handler->CreateServerToClientEncryptionHandler();
  this->send_encryption_handler = this->authentication_handler->CreateClientToServerEncryptionHandler();
  this->authentication_handler = nullptr;
 
  Debug(net, 9, "Client::status = ENCRYPTED");
  this->status = STATUS_ENCRYPTED;
 
  return this->SendIdentify();
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_WELCOME(Packet &p)
{
  if (this->status < STATUS_ENCRYPTED || this->status >= STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  Debug(net, 9, "Client::status = AUTHORIZED");
  this->status = STATUS_AUTHORIZED;
 
  _network_own_client_id = (ClientID)p.Recv_uint32();
 
  Debug(net, 9, "Client::Receive_SERVER_WELCOME(): client_id={}", _network_own_client_id);
 
  /* Start receiving the map */
  return SendGetMap();
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_WAIT(Packet &p)
{
  /* We set the internal wait state when requesting the map. */
  if (this->status != STATUS_MAP_WAIT) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  Debug(net, 9, "Client::Receive_SERVER_WAIT()");
 
  /* But... only now we set the join status to waiting, instead of requesting. */
  Debug(net, 9, "Client::join_status = WAITING");
  _network_join_status = NETWORK_JOIN_STATUS_WAITING;
  _network_join_waiting = p.Recv_uint8();
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_BEGIN(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED || this->status >= STATUS_MAP) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  Debug(net, 9, "Client::status = MAP");
  this->status = STATUS_MAP;
 
  if (this->savegame != nullptr) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  this->savegame = std::make_shared<PacketReader>();
 
  _frame_counter = _frame_counter_server = _frame_counter_max = p.Recv_uint32();
 
  Debug(net, 9, "Client::Receive_SERVER_MAP_BEGIN(): frame_counter={}", _frame_counter);
 
  _network_join_bytes = 0;
  _network_join_bytes_total = 0;
 
  Debug(net, 9, "Client::join_status = DOWNLOADING");
  _network_join_status = NETWORK_JOIN_STATUS_DOWNLOADING;
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_SIZE(Packet &p)
{
  if (this->status != STATUS_MAP) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  if (this->savegame == nullptr) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  _network_join_bytes_total = p.Recv_uint32();
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  Debug(net, 9, "Client::Receive_SERVER_MAP_SIZE(): bytes_total={}", _network_join_bytes_total);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_DATA(Packet &p)
{
  if (this->status != STATUS_MAP) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  if (this->savegame == nullptr) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  /* We are still receiving data, put it to the file */
  this->savegame->AddPacket(p);
 
  _network_join_bytes = (uint32_t)this->savegame->written_bytes;
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_DONE(Packet &)
{
  if (this->status != STATUS_MAP) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  if (this->savegame == nullptr) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  Debug(net, 9, "Client::Receive_SERVER_MAP_DONE()");
 
  Debug(net, 9, "Client::join_status = PROCESSING");
  _network_join_status = NETWORK_JOIN_STATUS_PROCESSING;
  SetWindowDirty(WC_NETWORK_STATUS_WINDOW, WN_NETWORK_STATUS_WINDOW_JOIN);
 
  this->savegame->Reset();
 
  /* The map is done downloading, load it */
  ClearErrorMessages();
 
  /* Set the abstract filetype. This is read during savegame load. */
  _file_to_saveload.SetMode(SLO_LOAD, FT_SAVEGAME, DFT_GAME_FILE);
 
  bool load_success = SafeLoad({}, SLO_LOAD, DFT_GAME_FILE, GM_NORMAL, NO_DIRECTORY, this->savegame);
  this->savegame = nullptr;
 
  /* Long savegame loads shouldn't affect the lag calculation! */
  this->last_packet = std::chrono::steady_clock::now();
 
  if (!load_success) {
    ShowErrorMessage(STR_NETWORK_ERROR_SAVEGAMEERROR, INVALID_STRING_ID, WL_CRITICAL);
    return NETWORK_RECV_STATUS_SAVEGAME;
  }
  /* If the savegame has successfully loaded, ALL windows have been removed,
   * only toolbar/statusbar and gamefield are visible */
 
  /* Say we received the map and loaded it correctly! */
  SendMapOk();
 
  /* As we skipped switch-mode, update the time we "switched". */
  _game_session_stats.start_time = std::chrono::steady_clock::now();
  _game_session_stats.savegame_size = std::nullopt;
 
  ShowClientList();
 
  /* New company/spectator (invalid company) or company we want to join is not active
   * Switch local company to spectator and await the server's judgement */
  if (_network_join.company == COMPANY_NEW_COMPANY || !Company::IsValidID(_network_join.company)) {
    SetLocalCompany(COMPANY_SPECTATOR);
 
    if (_network_join.company != COMPANY_SPECTATOR) {
      /* We have arrived and ready to start playing; send a command to make a new company;
       * the server will give us a client-id and let us in */
      Debug(net, 9, "Client::join_status = REGISTERING");
      _network_join_status = NETWORK_JOIN_STATUS_REGISTERING;
      ShowJoinStatusWindow();
      Command<CMD_COMPANY_CTRL>::Post(CCA_NEW, INVALID_COMPANY, CRR_NONE, _network_own_client_id);
    }
  } else {
    /* take control over an existing company */
    SetLocalCompany(_network_join.company);
  }
 
  SocialIntegration::EventEnterMultiplayer(Map::SizeX(), Map::SizeY());
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_FRAME(Packet &p)
{
  if (this->status != STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  _frame_counter_server = p.Recv_uint32();
  _frame_counter_max = p.Recv_uint32();
#ifdef ENABLE_NETWORK_SYNC_EVERY_FRAME
  /* Test if the server supports this option
   *  and if we are at the frame the server is */
#ifdef NETWORK_SEND_DOUBLE_SEED
  if (p.CanReadFromPacket(sizeof(uint32_t) + sizeof(uint32_t))) {
#else
  if (p.CanReadFromPacket(sizeof(uint32_t))) {
#endif
    _sync_frame = _frame_counter_server;
    _sync_seed_1 = p.Recv_uint32();
#ifdef NETWORK_SEND_DOUBLE_SEED
    _sync_seed_2 = p.Recv_uint32();
#endif
  }
#endif
  /* Receive the token. */
  if (p.CanReadFromPacket(sizeof(uint8_t))) this->token = p.Recv_uint8();
 
  /* Let the server know that we received this frame correctly
   *  We do this only once per day, to save some bandwidth ;) */
  if (!_network_first_time && last_ack_frame < _frame_counter) {
    last_ack_frame = _frame_counter + Ticks::DAY_TICKS;
    Debug(net, 7, "Sent ACK at {}", _frame_counter);
    SendAck();
  }
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_SYNC(Packet &p)
{
  if (this->status != STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  _sync_frame = p.Recv_uint32();
  _sync_seed_1 = p.Recv_uint32();
#ifdef NETWORK_SEND_DOUBLE_SEED
  _sync_seed_2 = p.Recv_uint32();
#endif
 
  Debug(net, 9, "Client::Receive_SERVER_SYNC(): sync_frame={}, sync_seed_1={}", _sync_frame, _sync_seed_1);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_COMMAND(Packet &p)
{
  if (this->status != STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  CommandPacket cp;
  const char *err = this->ReceiveCommand(p, cp);
  cp.frame    = p.Recv_uint32();
  cp.my_cmd   = p.Recv_bool();
 
  Debug(net, 9, "Client::Receive_SERVER_COMMAND(): cmd={}, frame={}", cp.cmd, cp.frame);
 
  if (err != nullptr) {
    IConsolePrint(CC_WARNING, "Dropping server connection due to {}.", err);
    return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  }
 
  this->incoming_queue.push_back(cp);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_CHAT(Packet &p)
{
  if (this->status != STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  std::string name;
  const NetworkClientInfo *ci = nullptr, *ci_to;
 
  NetworkAction action = (NetworkAction)p.Recv_uint8();
  ClientID client_id = (ClientID)p.Recv_uint32();
  bool self_send = p.Recv_bool();
  std::string msg = p.Recv_string(NETWORK_CHAT_LENGTH);
  int64_t data = p.Recv_uint64();
 
  Debug(net, 9, "Client::Receive_SERVER_CHAT(): action={}, client_id={}, self_send={}", action, client_id, self_send);
 
  ci_to = NetworkClientInfo::GetByClientID(client_id);
  if (ci_to == nullptr) return NETWORK_RECV_STATUS_OKAY;
 
  /* Did we initiate the action locally? */
  if (self_send) {
    switch (action) {
      case NETWORK_ACTION_CHAT_CLIENT:
        /* For speaking to client we need the client-name */
        name = ci_to->client_name;
        ci = NetworkClientInfo::GetByClientID(_network_own_client_id);
        break;
 
      /* For speaking to company, we need the company-name */
      case NETWORK_ACTION_CHAT_COMPANY: {
        StringID str = Company::IsValidID(ci_to->client_playas) ? STR_COMPANY_NAME : STR_NETWORK_SPECTATORS;
        SetDParam(0, ci_to->client_playas);
 
        name = GetString(str);
        ci = NetworkClientInfo::GetByClientID(_network_own_client_id);
        break;
      }
 
      default: return NETWORK_RECV_STATUS_MALFORMED_PACKET;
    }
  } else {
    /* Display message from somebody else */
    name = ci_to->client_name;
    ci = ci_to;
  }
 
  if (ci != nullptr) {
    NetworkTextMessage(action, GetDrawStringCompanyColour(ci->client_playas), self_send, name, msg, data);
  }
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_EXTERNAL_CHAT(Packet &p)
{
  if (this->status != STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  std::string source = p.Recv_string(NETWORK_CHAT_LENGTH);
  TextColour colour = (TextColour)p.Recv_uint16();
  std::string user = p.Recv_string(NETWORK_CHAT_LENGTH);
  std::string msg = p.Recv_string(NETWORK_CHAT_LENGTH);
 
  Debug(net, 9, "Client::Receive_SERVER_EXTERNAL_CHAT(): source={}", source);
 
  if (!IsValidConsoleColour(colour)) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  NetworkTextMessage(NETWORK_ACTION_EXTERNAL_CHAT, colour, false, user, msg, 0, source);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_ERROR_QUIT(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  ClientID client_id = (ClientID)p.Recv_uint32();
 
  Debug(net, 9, "Client::Receive_SERVER_ERROR_QUIT(): client_id={}", client_id);
 
  NetworkClientInfo *ci = NetworkClientInfo::GetByClientID(client_id);
  if (ci != nullptr) {
    NetworkTextMessage(NETWORK_ACTION_LEAVE, CC_DEFAULT, false, ci->client_name, "", GetNetworkErrorMsg((NetworkErrorCode)p.Recv_uint8()));
    delete ci;
  }
 
  InvalidateWindowData(WC_CLIENT_LIST, 0);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_QUIT(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  ClientID client_id = (ClientID)p.Recv_uint32();
 
  Debug(net, 9, "Client::Receive_SERVER_QUIT(): client_id={}", client_id);
 
  NetworkClientInfo *ci = NetworkClientInfo::GetByClientID(client_id);
  if (ci != nullptr) {
    NetworkTextMessage(NETWORK_ACTION_LEAVE, CC_DEFAULT, false, ci->client_name, "", STR_NETWORK_MESSAGE_CLIENT_LEAVING);
    delete ci;
  } else {
    Debug(net, 1, "Unknown client ({}) is leaving the game", client_id);
  }
 
  InvalidateWindowData(WC_CLIENT_LIST, 0);
 
  /* If we come here it means we could not locate the client.. strange :s */
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_JOIN(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  ClientID client_id = (ClientID)p.Recv_uint32();
 
  Debug(net, 9, "Client::Receive_SERVER_JOIN(): client_id={}", client_id);
 
  NetworkClientInfo *ci = NetworkClientInfo::GetByClientID(client_id);
  if (ci != nullptr) {
    NetworkTextMessage(NETWORK_ACTION_JOIN, CC_DEFAULT, false, ci->client_name);
  }
 
  InvalidateWindowData(WC_CLIENT_LIST, 0);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_SHUTDOWN(Packet &)
{
  Debug(net, 9, "Client::Receive_SERVER_SHUTDOWN()");
 
  /* Only when we're trying to join we really
   * care about the server shutting down. */
  if (this->status >= STATUS_JOIN) {
    ShowErrorMessage(STR_NETWORK_MESSAGE_SERVER_SHUTDOWN, INVALID_STRING_ID, WL_CRITICAL);
  }
 
  if (this->status == STATUS_ACTIVE) ClientNetworkEmergencySave();
 
  return NETWORK_RECV_STATUS_SERVER_ERROR;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_NEWGAME(Packet &)
{
  Debug(net, 9, "Client::Receive_SERVER_NEWGAME()");
 
  /* Only when we're trying to join we really
   * care about the server shutting down. */
  if (this->status >= STATUS_JOIN) {
    /* To throttle the reconnects a bit, every clients waits its
     * Client ID modulo 16 + 1 (value 0 means no reconnect).
     * This way reconnects should be spread out a bit. */
    _network_reconnect = _network_own_client_id % 16 + 1;
    ShowErrorMessage(STR_NETWORK_MESSAGE_SERVER_REBOOT, INVALID_STRING_ID, WL_CRITICAL);
  }
 
  if (this->status == STATUS_ACTIVE) ClientNetworkEmergencySave();
 
  return NETWORK_RECV_STATUS_SERVER_ERROR;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_RCON(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  Debug(net, 9, "Client::Receive_SERVER_RCON()");
 
  TextColour colour_code = (TextColour)p.Recv_uint16();
  if (!IsValidConsoleColour(colour_code)) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  std::string rcon_out = p.Recv_string(NETWORK_RCONCOMMAND_LENGTH);
 
  IConsolePrint(colour_code, rcon_out);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MOVE(Packet &p)
{
  if (this->status < STATUS_AUTHORIZED) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  /* Nothing more in this packet... */
  ClientID client_id   = (ClientID)p.Recv_uint32();
  CompanyID company_id = (CompanyID)p.Recv_uint8();
 
  Debug(net, 9, "Client::Receive_SERVER_MOVE(): client_id={}, comapny_id={}", client_id, company_id);
 
  if (client_id == 0) {
    /* definitely an invalid client id, debug message and do nothing. */
    Debug(net, 1, "Received invalid client index = 0");
    return NETWORK_RECV_STATUS_MALFORMED_PACKET;
  }
 
  const NetworkClientInfo *ci = NetworkClientInfo::GetByClientID(client_id);
  /* Just make sure we do not try to use a client_index that does not exist */
  if (ci == nullptr) return NETWORK_RECV_STATUS_OKAY;
 
  /* if not valid player, force spectator, else check player exists */
  if (!Company::IsValidID(company_id)) company_id = COMPANY_SPECTATOR;
 
  if (client_id == _network_own_client_id) {
    SetLocalCompany(company_id);
  }
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_CONFIG_UPDATE(Packet &p)
{
  if (this->status < STATUS_ACTIVE) return NETWORK_RECV_STATUS_MALFORMED_PACKET;
 
  _network_server_max_companies = p.Recv_uint8();
  _network_server_name = p.Recv_string(NETWORK_NAME_LENGTH);
 
  InvalidateWindowData(WC_CLIENT_LIST, 0);
 
  Debug(net, 9, "Client::Receive_SERVER_CONFIG_UPDATE(): max_companies={}", _network_server_max_companies);
 
  return NETWORK_RECV_STATUS_OKAY;
}
 
void ClientNetworkGameSocketHandler::CheckConnection()
{
  /* Only once we're authorized we can expect a steady stream of packets. */
  if (this->status < STATUS_AUTHORIZED) return;
 
  /* 5 seconds are roughly twice the server's "you're slow" threshold (1 game day). */
  std::chrono::steady_clock::duration lag = std::chrono::steady_clock::now() - this->last_packet;
  if (lag < std::chrono::seconds(5)) return;
 
  /* 20 seconds are (way) more than 4 game days after which
   * the server will forcefully disconnect you. */
  if (lag > std::chrono::seconds(20)) {
    this->NetworkGameSocketHandler::CloseConnection();
    return;
  }
 
  /* Prevent showing the lag message every tick; just update it when needed. */
  static std::chrono::steady_clock::duration last_lag = {};
  if (std::chrono::duration_cast<std::chrono::seconds>(last_lag) == std::chrono::duration_cast<std::chrono::seconds>(lag)) return;
 
  last_lag = lag;
  SetDParam(0, std::chrono::duration_cast<std::chrono::seconds>(lag).count());
  ShowErrorMessage(STR_NETWORK_ERROR_CLIENT_GUI_LOST_CONNECTION_CAPTION, STR_NETWORK_ERROR_CLIENT_GUI_LOST_CONNECTION, WL_INFO);
}
 
 
void NetworkClient_Connected()
{
  /* Set the frame-counter to 0 so nothing happens till we are ready */
  _frame_counter = 0;
  _frame_counter_server = 0;
  last_ack_frame = 0;
 
  Debug(net, 9, "Client::NetworkClient_Connected()");
 
  /* Request the game-info */
  MyClient::SendJoin();
}
 
void NetworkClientSendRcon(const std::string &password, const std::string &command)
{
  MyClient::SendRCon(password, command);
}
 
void NetworkClientRequestMove(CompanyID company_id)
{
  MyClient::SendMove(company_id);
}
 
void NetworkClientsToSpectators(CompanyID cid)
{
  Backup<CompanyID> cur_company(_current_company);
  /* If our company is changing owner, go to spectators */
  if (cid == _local_company) SetLocalCompany(COMPANY_SPECTATOR);
 
  for (NetworkClientInfo *ci : NetworkClientInfo::Iterate()) {
    if (ci->client_playas != cid) continue;
    NetworkTextMessage(NETWORK_ACTION_COMPANY_SPECTATOR, CC_DEFAULT, false, ci->client_name);
    ci->client_playas = COMPANY_SPECTATOR;
  }
 
  cur_company.Restore();
}
 
bool NetworkIsValidClientName(const std::string_view client_name)
{
  if (client_name.empty()) return false;
  if (client_name[0] == ' ') return false;
  return true;
}
 
bool NetworkValidateClientName(std::string &client_name)
{
  StrTrimInPlace(client_name);
  if (NetworkIsValidClientName(client_name)) return true;
 
  ShowErrorMessage(STR_NETWORK_ERROR_BAD_PLAYER_NAME, INVALID_STRING_ID, WL_ERROR);
  return false;
}
 
bool NetworkValidateOurClientName()
{
  return NetworkValidateClientName(_settings_client.network.client_name);
}
 
void NetworkUpdateClientName(const std::string &client_name)
{
  NetworkClientInfo *ci = NetworkClientInfo::GetByClientID(_network_own_client_id);
  if (ci == nullptr) return;
 
  /* Don't change the name if it is the same as the old name */
  if (client_name.compare(ci->client_name) != 0) {
    if (!_network_server) {
      MyClient::SendSetName(client_name);
    } else {
      /* Copy to a temporary buffer so no #n gets added after our name in the settings when there are duplicate names. */
      std::string temporary_name = client_name;
      if (NetworkMakeClientNameUnique(temporary_name)) {
        NetworkTextMessage(NETWORK_ACTION_NAME_CHANGE, CC_DEFAULT, false, ci->client_name, temporary_name);
        ci->client_name = temporary_name;
        NetworkUpdateClientInfo(CLIENT_ID_SERVER);
      }
    }
  }
}
 
void NetworkClientSendChat(NetworkAction action, DestType type, int dest, const std::string &msg, int64_t data)
{
  MyClient::SendChat(action, type, dest, msg, data);
}
 
bool NetworkClientPreferTeamChat(const NetworkClientInfo *cio)
{
  /* Only companies actually playing can speak to team. Eg spectators cannot */
  if (!_settings_client.gui.prefer_teamchat || !Company::IsValidID(cio->client_playas)) return false;
 
  for (const NetworkClientInfo *ci : NetworkClientInfo::Iterate()) {
    if (ci->client_playas == cio->client_playas && ci != cio) return true;
  }
 
  return false;
}
 
uint NetworkMaxCompaniesAllowed()
{
  return _network_server ? _settings_client.network.max_companies : _network_server_max_companies;
}
 
bool NetworkMaxCompaniesReached()
{
  return Company::GetNumItems() >= NetworkMaxCompaniesAllowed();
}