3 Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published by
7 the Free Software Foundation; either version 2.1 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
26 #include "serialization.h" // For SER_FMT_VER_INVALID
27 #include "content/mods.h"
28 #include "inventorymanager.h"
29 #include "content/subgames.h"
30 #include "tileanimation.h" // TileAnimationParams
31 #include "particles.h" // ParticleParams
32 #include "network/peerhandler.h"
33 #include "network/address.h"
34 #include "util/numeric.h"
35 #include "util/thread.h"
36 #include "util/basic_macros.h"
37 #include "util/metricsbackend.h"
38 #include "serverenvironment.h"
39 #include "clientiface.h"
40 #include "chatmessage.h"
41 #include "translation.h"
46 #include <unordered_set>
51 class IWritableItemDefManager;
53 class IWritableCraftDefManager;
60 struct PlayerHPChangeReason;
61 class IRollbackManager;
62 struct RollbackAction;
64 class ServerScripting;
65 class ServerEnvironment;
66 struct SimpleSoundSpec;
74 class ServerModManager;
75 class ServerInventoryManager;
78 enum ClientDeletionReason {
87 std::string sha1_digest; // base64-encoded
88 bool no_announce; // true: not announced in TOCLIENT_ANNOUNCE_MEDIA (at player join)
90 MediaInfo(const std::string &path_="",
91 const std::string &sha1_digest_=""):
93 sha1_digest(sha1_digest_),
99 // Combines the pure sound (SimpleSoundSpec) with positional information
100 struct ServerPlayingSound
102 SoundLocation type = SoundLocation::Local;
104 float gain = 1.0f; // for amplification of the base sound
105 float max_hear_distance = 32 * BS;
108 std::string to_player;
109 std::string exclude_player;
111 v3f getPos(ServerEnvironment *env, bool *pos_exists) const;
113 SimpleSoundSpec spec;
115 std::unordered_set<session_t> clients; // peer ids
119 MinimapType type = MINIMAP_TYPE_OFF;
126 // structure for everything getClientInfo returns, for convenience
133 u8 major, minor, patch;
134 std::string vers_string, lang_code;
137 class Server : public con::PeerHandler, public MapEventReceiver,
142 NOTE: Every public method should be thread-safe
146 const std::string &path_world,
147 const SubgameSpec &gamespec,
148 bool simple_singleplayer_mode,
151 ChatInterface *iface = nullptr,
152 std::string *on_shutdown_errmsg = nullptr
155 DISABLE_CLASS_COPY(Server);
159 // This is mainly a way to pass the time to the server.
160 // Actual processing is done in another thread.
161 void step(float dtime);
162 // This is run by ServerThread and does the actual processing
163 void AsyncRunStep(bool initial_step=false);
165 PlayerSAO* StageTwoClientInit(session_t peer_id);
171 void handleCommand(NetworkPacket* pkt);
173 void handleCommand_Null(NetworkPacket* pkt) {};
174 void handleCommand_Deprecated(NetworkPacket* pkt);
175 void handleCommand_Init(NetworkPacket* pkt);
176 void handleCommand_Init2(NetworkPacket* pkt);
177 void handleCommand_ModChannelJoin(NetworkPacket *pkt);
178 void handleCommand_ModChannelLeave(NetworkPacket *pkt);
179 void handleCommand_ModChannelMsg(NetworkPacket *pkt);
180 void handleCommand_RequestMedia(NetworkPacket* pkt);
181 void handleCommand_ClientReady(NetworkPacket* pkt);
182 void handleCommand_GotBlocks(NetworkPacket* pkt);
183 void handleCommand_PlayerPos(NetworkPacket* pkt);
184 void handleCommand_DeletedBlocks(NetworkPacket* pkt);
185 void handleCommand_InventoryAction(NetworkPacket* pkt);
186 void handleCommand_ChatMessage(NetworkPacket* pkt);
187 void handleCommand_Damage(NetworkPacket* pkt);
188 void handleCommand_PlayerItem(NetworkPacket* pkt);
189 void handleCommand_Respawn(NetworkPacket* pkt);
190 void handleCommand_Interact(NetworkPacket* pkt);
191 void handleCommand_RemovedSounds(NetworkPacket* pkt);
192 void handleCommand_NodeMetaFields(NetworkPacket* pkt);
193 void handleCommand_InventoryFields(NetworkPacket* pkt);
194 void handleCommand_FirstSrp(NetworkPacket* pkt);
195 void handleCommand_SrpBytesA(NetworkPacket* pkt);
196 void handleCommand_SrpBytesM(NetworkPacket* pkt);
197 void handleCommand_HaveMedia(NetworkPacket *pkt);
199 void ProcessData(NetworkPacket *pkt);
201 void Send(NetworkPacket *pkt);
202 void Send(session_t peer_id, NetworkPacket *pkt);
204 // Helper for handleCommand_PlayerPos and handleCommand_Interact
205 void process_PlayerPos(RemotePlayer *player, PlayerSAO *playersao,
208 // Both setter and getter need no envlock,
209 // can be called freely from threads
210 void setTimeOfDay(u32 time);
213 Shall be called with the environment locked.
214 This is accessed by the map, which is inside the environment,
215 so it shouldn't be a problem.
217 void onMapEditEvent(const MapEditEvent &event);
219 // Connection must be locked when called
220 std::string getStatusString();
221 inline double getUptime() const { return m_uptime_counter->get(); }
223 // read shutdown state
224 inline bool isShutdownRequested() const { return m_shutdown_state.is_requested; }
226 // request server to shutdown
227 void requestShutdown(const std::string &msg, bool reconnect, float delay = 0.0f);
229 // Returns -1 if failed, sound handle on success
231 s32 playSound(ServerPlayingSound ¶ms, bool ephemeral=false);
232 void stopSound(s32 handle);
233 void fadeSound(s32 handle, float step, float gain);
236 std::set<std::string> getPlayerEffectivePrivs(const std::string &name);
237 bool checkPriv(const std::string &name, const std::string &priv);
238 void reportPrivsModified(const std::string &name=""); // ""=all
239 void reportInventoryFormspecModified(const std::string &name);
240 void reportFormspecPrependModified(const std::string &name);
242 void setIpBanned(const std::string &ip, const std::string &name);
243 void unsetIpBanned(const std::string &ip_or_name);
244 std::string getBanDescription(const std::string &ip_or_name);
246 void notifyPlayer(const char *name, const std::wstring &msg);
247 void notifyPlayers(const std::wstring &msg);
249 void spawnParticle(const std::string &playername,
250 const ParticleParameters &p);
252 u32 addParticleSpawner(const ParticleSpawnerParameters &p,
253 ServerActiveObject *attached, const std::string &playername);
255 void deleteParticleSpawner(const std::string &playername, u32 id);
257 bool dynamicAddMedia(std::string filepath, u32 token,
258 const std::string &to_player, bool ephemeral);
260 ServerInventoryManager *getInventoryMgr() const { return m_inventory_mgr.get(); }
261 void sendDetachedInventory(Inventory *inventory, const std::string &name, session_t peer_id);
263 // Envlock and conlock should be locked when using scriptapi
264 ServerScripting *getScriptIface(){ return m_script; }
266 // actions: time-reversed list
267 // Return value: success/failure
268 bool rollbackRevertActions(const std::list<RollbackAction> &actions,
269 std::list<std::string> *log);
271 // IGameDef interface
273 virtual IItemDefManager* getItemDefManager();
274 virtual const NodeDefManager* getNodeDefManager();
275 virtual ICraftDefManager* getCraftDefManager();
276 virtual u16 allocateUnknownNodeId(const std::string &name);
277 IRollbackManager *getRollbackManager() { return m_rollback; }
278 virtual EmergeManager *getEmergeManager() { return m_emerge; }
279 virtual ModStorageDatabase *getModStorageDatabase() { return m_mod_storage_database; }
281 IWritableItemDefManager* getWritableItemDefManager();
282 NodeDefManager* getWritableNodeDefManager();
283 IWritableCraftDefManager* getWritableCraftDefManager();
285 virtual const std::vector<ModSpec> &getMods() const;
286 virtual const ModSpec* getModSpec(const std::string &modname) const;
287 virtual const SubgameSpec* getGameSpec() const { return &m_gamespec; }
288 static std::string getBuiltinLuaPath();
289 virtual std::string getWorldPath() const { return m_path_world; }
291 inline bool isSingleplayer() const
292 { return m_simple_singleplayer_mode; }
294 inline void setAsyncFatalError(const std::string &error)
295 { m_async_fatal_error.set(error); }
296 inline void setAsyncFatalError(const LuaError &e)
298 setAsyncFatalError(std::string("Lua: ") + e.what());
301 bool showFormspec(const char *name, const std::string &formspec, const std::string &formname);
302 Map & getMap() { return m_env->getMap(); }
303 ServerEnvironment & getEnv() { return *m_env; }
306 u32 hudAdd(RemotePlayer *player, HudElement *element);
307 bool hudRemove(RemotePlayer *player, u32 id);
308 bool hudChange(RemotePlayer *player, u32 id, HudElementStat stat, void *value);
309 bool hudSetFlags(RemotePlayer *player, u32 flags, u32 mask);
310 bool hudSetHotbarItemcount(RemotePlayer *player, s32 hotbar_itemcount);
311 void hudSetHotbarImage(RemotePlayer *player, const std::string &name);
312 void hudSetHotbarSelectedImage(RemotePlayer *player, const std::string &name);
314 Address getPeerAddress(session_t peer_id);
316 void setLocalPlayerAnimations(RemotePlayer *player, v2s32 animation_frames[4],
318 void setPlayerEyeOffset(RemotePlayer *player, const v3f &first, const v3f &third);
320 void setSky(RemotePlayer *player, const SkyboxParams ¶ms);
321 void setSun(RemotePlayer *player, const SunParams ¶ms);
322 void setMoon(RemotePlayer *player, const MoonParams ¶ms);
323 void setStars(RemotePlayer *player, const StarParams ¶ms);
325 void setClouds(RemotePlayer *player, const CloudParams ¶ms);
327 void overrideDayNightRatio(RemotePlayer *player, bool do_override, float brightness);
329 void setLighting(RemotePlayer *player, const Lighting &lighting);
331 void RespawnPlayer(session_t peer_id);
333 /* con::PeerHandler implementation. */
334 void peerAdded(con::Peer *peer);
335 void deletingPeer(con::Peer *peer, bool timeout);
337 void DenySudoAccess(session_t peer_id);
338 void DenyAccess(session_t peer_id, AccessDeniedCode reason,
339 const std::string &custom_reason = "", bool reconnect = false);
340 void acceptAuth(session_t peer_id, bool forSudoMode);
341 void DisconnectPeer(session_t peer_id);
342 bool getClientConInfo(session_t peer_id, con::rtt_stat_type type, float *retval);
343 bool getClientInfo(session_t peer_id, ClientInfo &ret);
345 void printToConsoleOnly(const std::string &text);
347 void HandlePlayerHPChange(PlayerSAO *sao, const PlayerHPChangeReason &reason);
348 void SendPlayerHP(PlayerSAO *sao, bool effect);
349 void SendPlayerBreath(PlayerSAO *sao);
350 void SendInventory(PlayerSAO *playerSAO, bool incremental);
351 void SendMovePlayer(session_t peer_id);
352 void SendPlayerSpeed(session_t peer_id, const v3f &added_vel);
353 void SendPlayerFov(session_t peer_id);
355 void SendMinimapModes(session_t peer_id,
356 std::vector<MinimapMode> &modes,
359 void sendDetachedInventories(session_t peer_id, bool incremental);
361 bool joinModChannel(const std::string &channel);
362 bool leaveModChannel(const std::string &channel);
363 bool sendModChannelMessage(const std::string &channel, const std::string &message);
364 ModChannel *getModChannel(const std::string &channel);
366 // Send block to specific player only
367 bool SendBlock(session_t peer_id, const v3s16 &blockpos);
369 // Get or load translations for a language
370 Translations *getTranslationLanguage(const std::string &lang_code);
372 static ModStorageDatabase *openModStorageDatabase(const std::string &world_path);
374 static ModStorageDatabase *openModStorageDatabase(const std::string &backend,
375 const std::string &world_path, const Settings &world_mt);
377 static bool migrateModStorageDatabase(const GameParams &game_params,
378 const Settings &cmd_args);
380 // Lua files registered for init of async env, pair of modname + path
381 std::vector<std::pair<std::string, std::string>> m_async_init_files;
383 // Data transferred into async envs at init time
384 std::unique_ptr<PackedValue> m_async_globals_data;
389 // Environment mutex (envlock)
390 std::mutex m_env_mutex;
393 friend class EmergeThread;
394 friend class RemoteClient;
395 friend class TestServerShutdownState;
397 struct ShutdownState {
398 friend class TestServerShutdownState;
400 bool is_requested = false;
401 bool should_reconnect = false;
405 void trigger(float delay, const std::string &msg, bool reconnect);
406 void tick(float dtime, Server *server);
407 std::wstring getShutdownTimerMessage() const;
408 bool isTimerRunning() const { return m_timer > 0.0f; }
410 float m_timer = 0.0f;
413 struct PendingDynamicMediaCallback {
414 std::string filename; // only set if media entry and file is to be deleted
416 std::unordered_set<session_t> waiting_players;
419 // The standard library does not implement std::hash for pairs so we have this:
421 size_t operator() (const std::pair<v3s16, u16> &p) const {
422 return std::hash<v3s16>()(p.first) ^ p.second;
426 typedef std::unordered_map<std::pair<v3s16, u16>, std::string, SBCHash> SerializedBlockCache;
430 void SendMovement(session_t peer_id);
431 void SendHP(session_t peer_id, u16 hp, bool effect);
432 void SendBreath(session_t peer_id, u16 breath);
433 void SendAccessDenied(session_t peer_id, AccessDeniedCode reason,
434 const std::string &custom_reason, bool reconnect = false);
435 void SendAccessDenied_Legacy(session_t peer_id, const std::wstring &reason);
436 void SendDeathscreen(session_t peer_id, bool set_camera_point_target,
437 v3f camera_point_target);
438 void SendItemDef(session_t peer_id, IItemDefManager *itemdef, u16 protocol_version);
439 void SendNodeDef(session_t peer_id, const NodeDefManager *nodedef,
440 u16 protocol_version);
443 virtual void SendChatMessage(session_t peer_id, const ChatMessage &message);
444 void SendTimeOfDay(session_t peer_id, u16 time, f32 time_speed);
446 void SendLocalPlayerAnimations(session_t peer_id, v2s32 animation_frames[4],
447 f32 animation_speed);
448 void SendEyeOffset(session_t peer_id, v3f first, v3f third);
449 void SendPlayerPrivileges(session_t peer_id);
450 void SendPlayerInventoryFormspec(session_t peer_id);
451 void SendPlayerFormspecPrepend(session_t peer_id);
452 void SendShowFormspecMessage(session_t peer_id, const std::string &formspec,
453 const std::string &formname);
454 void SendHUDAdd(session_t peer_id, u32 id, HudElement *form);
455 void SendHUDRemove(session_t peer_id, u32 id);
456 void SendHUDChange(session_t peer_id, u32 id, HudElementStat stat, void *value);
457 void SendHUDSetFlags(session_t peer_id, u32 flags, u32 mask);
458 void SendHUDSetParam(session_t peer_id, u16 param, const std::string &value);
459 void SendSetSky(session_t peer_id, const SkyboxParams ¶ms);
460 void SendSetSun(session_t peer_id, const SunParams ¶ms);
461 void SendSetMoon(session_t peer_id, const MoonParams ¶ms);
462 void SendSetStars(session_t peer_id, const StarParams ¶ms);
463 void SendCloudParams(session_t peer_id, const CloudParams ¶ms);
464 void SendOverrideDayNightRatio(session_t peer_id, bool do_override, float ratio);
465 void SendSetLighting(session_t peer_id, const Lighting &lighting);
466 void broadcastModChannelMessage(const std::string &channel,
467 const std::string &message, session_t from_peer);
470 Send a node removal/addition event to all clients except ignore_id.
471 Additionally, if far_players!=NULL, players further away than
472 far_d_nodes are ignored and their peer_ids are added to far_players
474 // Envlock and conlock should be locked when calling these
475 void sendRemoveNode(v3s16 p, std::unordered_set<u16> *far_players = nullptr,
476 float far_d_nodes = 100);
477 void sendAddNode(v3s16 p, MapNode n,
478 std::unordered_set<u16> *far_players = nullptr,
479 float far_d_nodes = 100, bool remove_metadata = true);
480 void sendNodeChangePkt(NetworkPacket &pkt, v3s16 block_pos,
481 v3f p, float far_d_nodes, std::unordered_set<u16> *far_players);
483 void sendMetadataChanged(const std::unordered_set<v3s16> &positions,
484 float far_d_nodes = 100);
486 // Environment and Connection must be locked when called
487 // `cache` may only be very short lived! (invalidation not handeled)
488 void SendBlockNoLock(session_t peer_id, MapBlock *block, u8 ver,
489 u16 net_proto_version, SerializedBlockCache *cache = nullptr);
491 // Sends blocks to clients (locks env and con on its own)
492 void SendBlocks(float dtime);
494 bool addMediaFile(const std::string &filename, const std::string &filepath,
495 std::string *filedata = nullptr, std::string *digest = nullptr);
496 void fillMediaCache();
497 void sendMediaAnnouncement(session_t peer_id, const std::string &lang_code);
498 void sendRequestedMedia(session_t peer_id,
499 const std::vector<std::string> &tosend);
500 void stepPendingDynMediaCallbacks(float dtime);
502 // Adds a ParticleSpawner on peer with peer_id (PEER_ID_INEXISTENT == all)
503 void SendAddParticleSpawner(session_t peer_id, u16 protocol_version,
504 const ParticleSpawnerParameters &p, u16 attached_id, u32 id);
506 void SendDeleteParticleSpawner(session_t peer_id, u32 id);
508 // Spawns particle on peer with peer_id (PEER_ID_INEXISTENT == all)
509 void SendSpawnParticle(session_t peer_id, u16 protocol_version,
510 const ParticleParameters &p);
512 void SendActiveObjectRemoveAdd(RemoteClient *client, PlayerSAO *playersao);
513 void SendActiveObjectMessages(session_t peer_id, const std::string &datas,
514 bool reliable = true);
515 void SendCSMRestrictionFlags(session_t peer_id);
521 void HandlePlayerDeath(PlayerSAO* sao, const PlayerHPChangeReason &reason);
522 void DeleteClient(session_t peer_id, ClientDeletionReason reason);
523 void UpdateCrafting(RemotePlayer *player);
524 bool checkInteractDistance(RemotePlayer *player, const f32 d, const std::string &what);
526 void handleChatInterfaceEvent(ChatEvent *evt);
528 // This returns the answer to the sender of wmessage, or "" if there is none
529 std::wstring handleChat(const std::string &name, std::wstring wmessage_input,
530 bool check_shout_priv = false, RemotePlayer *player = nullptr);
531 void handleAdminChat(const ChatEventChat *evt);
533 // When called, connection mutex should be locked
534 RemoteClient* getClient(session_t peer_id, ClientState state_min = CS_Active);
535 RemoteClient* getClientNoEx(session_t peer_id, ClientState state_min = CS_Active);
537 // When called, environment mutex should be locked
538 std::string getPlayerName(session_t peer_id);
539 PlayerSAO *getPlayerSAO(session_t peer_id);
542 Get a player from memory or creates one.
543 If player is already connected, return NULL
544 Does not verify/modify auth info and password.
546 Call with env and con locked.
548 PlayerSAO *emergePlayer(const char *name, session_t peer_id, u16 proto_version);
550 void handlePeerChanges();
556 std::string m_path_world;
557 // Subgame specification
558 SubgameSpec m_gamespec;
559 // If true, do not allow multiple players and hide some multiplayer
561 bool m_simple_singleplayer_mode;
562 u16 m_max_chatmessage_length;
563 // For "dedicated" server list flag
565 Settings *m_game_settings = nullptr;
567 // Thread can set; step() will throw as ServerError
568 MutexedVariable<std::string> m_async_fatal_error;
571 float m_liquid_transform_timer = 0.0f;
572 float m_liquid_transform_every = 1.0f;
573 float m_masterserver_timer = 0.0f;
574 float m_emergethread_trigger_timer = 0.0f;
575 float m_savemap_timer = 0.0f;
576 IntervalLimiter m_map_timer_and_unload_interval;
579 ServerEnvironment *m_env = nullptr;
581 // Reference to the server map until ServerEnvironment is initialized
582 // after that this variable must be a nullptr
583 ServerMap *m_startup_server_map = nullptr;
586 std::shared_ptr<con::Connection> m_con;
589 BanManager *m_banmanager = nullptr;
591 // Rollback manager (behind m_env_mutex)
592 IRollbackManager *m_rollback = nullptr;
595 EmergeManager *m_emerge = nullptr;
598 // Envlock and conlock should be locked when using Lua
599 ServerScripting *m_script = nullptr;
601 // Item definition manager
602 IWritableItemDefManager *m_itemdef;
604 // Node definition manager
605 NodeDefManager *m_nodedef;
607 // Craft definition manager
608 IWritableCraftDefManager *m_craftdef;
611 std::unique_ptr<ServerModManager> m_modmgr;
613 std::unordered_map<std::string, Translations> server_translations;
618 // A buffer for time steps
619 // step() increments and AsyncRunStep() run by m_thread reads it.
620 float m_step_dtime = 0.0f;
621 std::mutex m_step_dtime_mutex;
623 // The server mainly operates in this thread
624 ServerThread *m_thread = nullptr;
629 // Timer for sending time of day over network
630 float m_time_of_day_send_timer = 0.0f;
635 ClientInterface m_clients;
639 Queues stuff from peerAdded() and deletingPeer() to
642 std::queue<con::PeerChange> m_peer_change_queue;
644 std::unordered_map<session_t, std::string> m_formspec_state_data;
650 ShutdownState m_shutdown_state;
652 ChatInterface *m_admin_chat;
653 std::string m_admin_nick;
655 // if a mod-error occurs in the on_shutdown callback, the error message will
656 // be written into this
657 std::string *const m_on_shutdown_errmsg;
660 Map edit event queue. Automatically receives all map edits.
661 The constructor of this class registers us to receive them through
664 NOTE: Should these be moved to actually be members of
669 Queue of map edits from the environment for sending to the clients
670 This is behind m_env_mutex
672 std::queue<MapEditEvent*> m_unsent_map_edit_queue;
674 If a non-empty area, map edit events contained within are left
675 unsent. Done at map generation time to speed up editing of the
676 generated area, as it will be sent anyway.
677 This is behind m_env_mutex
679 VoxelArea m_ignore_map_edit_events_area;
681 // media files known to server
682 std::unordered_map<std::string, MediaInfo> m_media;
684 // pending dynamic media callbacks, clients inform the server when they have a file fetched
685 std::unordered_map<u32, PendingDynamicMediaCallback> m_pending_dyn_media;
686 float m_step_pending_dyn_media_timer = 0.0f;
691 std::unordered_map<s32, ServerPlayingSound> m_playing_sounds;
692 s32 m_next_sound_id = 0; // positive values only
695 ModStorageDatabase *m_mod_storage_database = nullptr;
696 float m_mod_storage_save_timer = 10.0f;
698 // CSM restrictions byteflag
699 u64 m_csm_restriction_flags = CSMRestrictionFlags::CSM_RF_NONE;
700 u32 m_csm_restriction_noderange = 8;
702 // ModChannel manager
703 std::unique_ptr<ModChannelMgr> m_modchannel_mgr;
706 std::unique_ptr<ServerInventoryManager> m_inventory_mgr;
708 // Global server metrics backend
709 std::unique_ptr<MetricsBackend> m_metrics_backend;
712 MetricCounterPtr m_uptime_counter;
713 MetricGaugePtr m_player_gauge;
714 MetricGaugePtr m_timeofday_gauge;
715 MetricGaugePtr m_lag_gauge;
716 MetricCounterPtr m_aom_buffer_counter[2]; // [0] = rel, [1] = unrel
717 MetricCounterPtr m_packet_recv_counter;
718 MetricCounterPtr m_packet_recv_processed_counter;
719 MetricCounterPtr m_map_edit_event_counter;
723 Runs a simple dedicated server loop.
725 Shuts down when kill is set to true.
727 void dedicated_server_loop(Server &server, bool &kill);