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[blank.git] / src / server / net.cpp
1 #include "ClientConnection.hpp"
2 #include "ChunkTransmitter.hpp"
3 #include "Server.hpp"
4
5 #include "../app/init.hpp"
6 #include "../io/WorldSave.hpp"
7 #include "../model/Model.hpp"
8 #include "../world/ChunkIndex.hpp"
9 #include "../world/Entity.hpp"
10 #include "../world/World.hpp"
11
12 #include <algorithm>
13 #include <iostream>
14 #include <zlib.h>
15 #include <glm/gtx/io.hpp>
16
17 using namespace std;
18
19
20 namespace blank {
21 namespace server {
22
23 ChunkTransmitter::ChunkTransmitter(ClientConnection &conn)
24 : conn(conn)
25 , current(nullptr)
26 , buffer_size(Chunk::BlockSize() + 10)
27 , buffer(new uint8_t[buffer_size])
28 , buffer_len(0)
29 , packet_len(Packet::ChunkData::MAX_DATA_LEN)
30 , cursor(0)
31 , num_packets(0)
32 , begin_packet(-1)
33 , data_packets()
34 , confirm_wait(0)
35 , trans_id(0)
36 , compressed(false) {
37
38 }
39
40 ChunkTransmitter::~ChunkTransmitter() {
41         Abort();
42 }
43
44 bool ChunkTransmitter::Idle() const noexcept {
45         return !Transmitting() && !Waiting();
46 }
47
48 bool ChunkTransmitter::Transmitting() const noexcept {
49         return cursor < num_packets;
50 }
51
52 void ChunkTransmitter::Transmit() {
53         if (cursor < num_packets) {
54                 SendData(cursor);
55                 ++cursor;
56         }
57 }
58
59 bool ChunkTransmitter::Waiting() const noexcept {
60         return confirm_wait > 0;
61 }
62
63 void ChunkTransmitter::Ack(uint16_t seq) {
64         if (!Waiting()) {
65                 return;
66         }
67         if (seq == begin_packet) {
68                 begin_packet = -1;
69                 --confirm_wait;
70                 if (Idle()) {
71                         Release();
72                 }
73                 return;
74         }
75         for (int i = 0, end = data_packets.size(); i < end; ++i) {
76                 if (seq == data_packets[i]) {
77                         data_packets[i] = -1;
78                         --confirm_wait;
79                         if (Idle()) {
80                                 Release();
81                         }
82                         return;
83                 }
84         }
85 }
86
87 void ChunkTransmitter::Nack(uint16_t seq) {
88         if (!Waiting()) {
89                 return;
90         }
91         if (seq == begin_packet) {
92                 SendBegin();
93                 return;
94         }
95         for (size_t i = 0, end = data_packets.size(); i < end; ++i) {
96                 if (seq == data_packets[i]) {
97                         SendData(i);
98                         return;
99                 }
100         }
101 }
102
103 void ChunkTransmitter::Abort() {
104         if (!current) return;
105
106         Release();
107
108         begin_packet = -1;
109         data_packets.clear();
110         confirm_wait = 0;
111 }
112
113 void ChunkTransmitter::Send(Chunk &chunk) {
114         // abort current chunk, if any
115         Abort();
116
117         current = &chunk;
118         current->Ref();
119
120         // load new chunk data
121         compressed = true;
122         buffer_len = buffer_size;
123         if (compress(buffer.get(), &buffer_len, reinterpret_cast<const Bytef *>(chunk.BlockData()), Chunk::BlockSize()) != Z_OK) {
124                 // compression failed, send it uncompressed
125                 buffer_len = Chunk::BlockSize();
126                 memcpy(buffer.get(), chunk.BlockData(), buffer_len);
127                 compressed = false;
128         }
129         cursor = 0;
130         num_packets = (buffer_len / packet_len) + (buffer_len % packet_len != 0);
131         data_packets.resize(num_packets, -1);
132
133         ++trans_id;
134         SendBegin();
135 }
136
137 void ChunkTransmitter::SendBegin() {
138         uint32_t flags = compressed;
139         auto pack = conn.Prepare<Packet::ChunkBegin>();
140         pack.WriteTransmissionId(trans_id);
141         pack.WriteFlags(flags);
142         pack.WriteChunkCoords(current->Position());
143         pack.WriteDataSize(buffer_len);
144         if (begin_packet == -1) {
145                 ++confirm_wait;
146         }
147         begin_packet = conn.Send();
148 }
149
150 void ChunkTransmitter::SendData(size_t i) {
151         int pos = i * packet_len;
152         int len = min(packet_len, buffer_len - pos);
153         const uint8_t *data = &buffer[pos];
154
155         auto pack = conn.Prepare<Packet::ChunkData>();
156         pack.WriteTransmissionId(trans_id);
157         pack.WriteDataOffset(pos);
158         pack.WriteDataSize(len);
159         pack.WriteData(data, len);
160
161         if (data_packets[i] == -1) {
162                 ++confirm_wait;
163         }
164         data_packets[i] = conn.Send();
165 }
166
167 void ChunkTransmitter::Release() {
168         if (current) {
169                 current->UnRef();
170                 current = nullptr;
171         }
172 }
173
174
175 ClientConnection::ClientConnection(Server &server, const IPaddress &addr)
176 : server(server)
177 , conn(addr)
178 , input()
179 , player_model(nullptr)
180 , spawns()
181 , confirm_wait(0)
182 , entity_updates()
183 , player_update_state()
184 , player_update_pack(0)
185 , player_update_timer(1500)
186 , old_actions(0)
187 , transmitter(*this)
188 , chunk_queue()
189 , old_base() {
190         conn.SetHandler(this);
191 }
192
193 ClientConnection::~ClientConnection() {
194         DetachPlayer();
195 }
196
197 void ClientConnection::Update(int dt) {
198         conn.Update(dt);
199         if (Disconnected()) {
200                 return;
201         }
202         if (HasPlayer()) {
203                 // sync entities
204                 auto global_iter = server.GetWorld().Entities().begin();
205                 auto global_end = server.GetWorld().Entities().end();
206                 auto local_iter = spawns.begin();
207                 auto local_end = spawns.end();
208
209                 while (global_iter != global_end && local_iter != local_end) {
210                         if (global_iter->ID() == local_iter->entity->ID()) {
211                                 // they're the same
212                                 if (CanDespawn(*global_iter)) {
213                                         SendDespawn(*local_iter);
214                                 } else {
215                                         // update
216                                         QueueUpdate(*local_iter);
217                                 }
218                                 ++global_iter;
219                                 ++local_iter;
220                         } else if (global_iter->ID() < local_iter->entity->ID()) {
221                                 // global entity was inserted
222                                 if (CanSpawn(*global_iter)) {
223                                         auto spawned = spawns.emplace(local_iter, *global_iter);
224                                         SendSpawn(*spawned);
225                                 }
226                                 ++global_iter;
227                         } else {
228                                 // global entity was removed
229                                 SendDespawn(*local_iter);
230                                 ++local_iter;
231                         }
232                 }
233
234                 // leftover spawns
235                 while (global_iter != global_end) {
236                         if (CanSpawn(*global_iter)) {
237                                 spawns.emplace_back(*global_iter);
238                                 SendSpawn(spawns.back());
239                         }
240                         ++global_iter;
241                 }
242
243                 // leftover despawns
244                 while (local_iter != local_end) {
245                         SendDespawn(*local_iter);
246                         ++local_iter;
247                 }
248                 SendUpdates();
249
250                 CheckPlayerFix();
251                 CheckChunkQueue();
252         }
253         if (conn.ShouldPing()) {
254                 conn.SendPing(server.GetPacket(), server.GetSocket());
255         }
256 }
257
258 ClientConnection::SpawnStatus::SpawnStatus(Entity &e)
259 : entity(&e)
260 , spawn_pack(-1)
261 , despawn_pack(-1) {
262         entity->Ref();
263 }
264
265 ClientConnection::SpawnStatus::~SpawnStatus() {
266         entity->UnRef();
267 }
268
269 bool ClientConnection::CanSpawn(const Entity &e) const noexcept {
270         return
271                 &e != &PlayerEntity() &&
272                 !e.Dead() &&
273                 manhattan_radius(e.ChunkCoords() - PlayerEntity().ChunkCoords()) < 7;
274 }
275
276 bool ClientConnection::CanDespawn(const Entity &e) const noexcept {
277         return
278                 e.Dead() ||
279                 manhattan_radius(e.ChunkCoords() - PlayerEntity().ChunkCoords()) > 7;
280 }
281
282 uint16_t ClientConnection::Send() {
283         return conn.Send(server.GetPacket(), server.GetSocket());
284 }
285
286 uint16_t ClientConnection::Send(size_t len) {
287         server.GetPacket().len = sizeof(Packet::Header) + len;
288         return Send();
289 }
290
291 void ClientConnection::SendSpawn(SpawnStatus &status) {
292         // don't double spawn
293         if (status.spawn_pack != -1) return;
294
295         auto pack = Prepare<Packet::SpawnEntity>();
296         pack.WriteEntity(*status.entity);
297         status.spawn_pack = Send();
298         ++confirm_wait;
299 }
300
301 void ClientConnection::SendDespawn(SpawnStatus &status) {
302         // don't double despawn
303         if (status.despawn_pack != -1) return;
304
305         auto pack = Prepare<Packet::DespawnEntity>();
306         pack.WriteEntityID(status.entity->ID());
307         status.despawn_pack = Send();
308         ++confirm_wait;
309 }
310
311 void ClientConnection::QueueUpdate(SpawnStatus &status) {
312         // don't send updates while spawn not ack'd or despawn sent
313         if (status.spawn_pack == -1 && status.despawn_pack == -1) {
314                 entity_updates.push_back(&status);
315         }
316 }
317
318 void ClientConnection::SendUpdates() {
319         auto base = PlayerChunks().Base();
320         auto pack = Prepare<Packet::EntityUpdate>();
321         pack.WriteChunkBase(base);
322         int entity_pos = 0;
323         for (SpawnStatus *status : entity_updates) {
324                 pack.WriteEntity(*status->entity, base, entity_pos);
325                 ++entity_pos;
326                 if (entity_pos == Packet::EntityUpdate::MAX_ENTITIES) {
327                         pack.WriteEntityCount(entity_pos);
328                         Send(Packet::EntityUpdate::GetSize(entity_pos));
329                         pack = Prepare<Packet::EntityUpdate>();
330                         entity_pos = 0;
331                 }
332         }
333         if (entity_pos > 0) {
334                 pack.WriteEntityCount(entity_pos);
335                 Send(Packet::EntityUpdate::GetSize(entity_pos));
336         }
337         entity_updates.clear();
338 }
339
340 void ClientConnection::CheckPlayerFix() {
341         // player_update_state's position holds the client's most recent prediction
342         glm::vec3 diff = player_update_state.Diff(PlayerEntity().GetState());
343         float dist_squared = dot(diff, diff);
344
345         // if client's prediction is off by more than 1cm, send
346         // our (authoritative) state back so it can fix it
347         constexpr float fix_thresh = 0.0001f;
348
349         if (dist_squared > fix_thresh) {
350                 auto pack = Prepare<Packet::PlayerCorrection>();
351                 pack.WritePacketSeq(player_update_pack);
352                 pack.WritePlayer(PlayerEntity());
353                 Send();
354         }
355 }
356
357 namespace {
358
359 struct QueueCompare {
360         explicit QueueCompare(const glm::ivec3 &base)
361         : base(base) { }
362         bool operator ()(const glm::ivec3 &left, const glm::ivec3 &right) const noexcept {
363                 const glm::ivec3 ld(left - base);
364                 const glm::ivec3 rd(right - base);
365                 return
366                         ld.x * ld.x + ld.y * ld.y + ld.z * ld.z <
367                         rd.x * rd.x + rd.y * rd.y + rd.z * rd.z;
368         }
369         const glm::ivec3 &base;
370 };
371
372 }
373
374 void ClientConnection::CheckChunkQueue() {
375         if (PlayerChunks().Base() != old_base) {
376                 Chunk::Pos begin = PlayerChunks().CoordsBegin();
377                 Chunk::Pos end = PlayerChunks().CoordsEnd();
378                 for (Chunk::Pos pos = begin; pos.z < end.z; ++pos.z) {
379                         for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
380                                 for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
381                                         if (manhattan_radius(pos - old_base) > PlayerChunks().Extent()) {
382                                                 chunk_queue.push_back(pos);
383                                         }
384                                 }
385                         }
386                 }
387                 old_base = PlayerChunks().Base();
388                 sort(chunk_queue.begin(), chunk_queue.end(), QueueCompare(old_base));
389         }
390         if (transmitter.Transmitting()) {
391                 transmitter.Transmit();
392                 return;
393         }
394         if (transmitter.Idle()) {
395                 int count = 0;
396                 constexpr int max = 64;
397                 while (count < max && !chunk_queue.empty()) {
398                         Chunk::Pos pos = chunk_queue.front();
399                         chunk_queue.pop_front();
400                         if (PlayerChunks().InRange(pos)) {
401                                 Chunk *chunk = PlayerChunks().Get(pos);
402                                 if (chunk) {
403                                         transmitter.Send(*chunk);
404                                         return;
405                                 } else {
406                                         chunk_queue.push_back(pos);
407                                 }
408                                 ++count;
409                         }
410                 }
411         }
412 }
413
414 void ClientConnection::AttachPlayer(Player &player) {
415         DetachPlayer();
416         input.reset(new DirectInput(server.GetWorld(), player, server));
417         PlayerEntity().Ref();
418
419         old_base = PlayerChunks().Base();
420         Chunk::Pos begin = PlayerChunks().CoordsBegin();
421         Chunk::Pos end = PlayerChunks().CoordsEnd();
422         for (Chunk::Pos pos = begin; pos.z < end.z; ++pos.z) {
423                 for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
424                         for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
425                                 chunk_queue.push_back(pos);
426                         }
427                 }
428         }
429         sort(chunk_queue.begin(), chunk_queue.end(), QueueCompare(old_base));
430         // TODO: should the server do this?
431         if (HasPlayerModel()) {
432                 GetPlayerModel().Instantiate(PlayerEntity().GetModel());
433         }
434
435         string msg = "player \"" + player.Name() + "\" joined";
436         cout << msg << endl;
437         server.DistributeMessage(0, 0, msg);
438 }
439
440 void ClientConnection::DetachPlayer() {
441         if (!HasPlayer()) return;
442         string msg = "player \"" + input->GetPlayer().Name() + "\" left";
443         cout << msg << endl;
444         server.DistributeMessage(0, 0, msg);
445
446         server.GetWorldSave().Write(input->GetPlayer());
447         PlayerEntity().Kill();
448         PlayerEntity().UnRef();
449         input.reset();
450         transmitter.Abort();
451         chunk_queue.clear();
452         old_actions = 0;
453 }
454
455 void ClientConnection::SetPlayerModel(const Model &m) noexcept {
456         player_model = &m;
457         if (HasPlayer()) {
458                 m.Instantiate(PlayerEntity().GetModel());
459         }
460 }
461
462 bool ClientConnection::HasPlayerModel() const noexcept {
463         return player_model;
464 }
465
466 const Model &ClientConnection::GetPlayerModel() const noexcept {
467         return *player_model;
468 }
469
470 void ClientConnection::OnPacketReceived(uint16_t seq) {
471         if (transmitter.Waiting()) {
472                 transmitter.Ack(seq);
473         }
474         if (!confirm_wait) return;
475         for (auto iter = spawns.begin(), end = spawns.end(); iter != end; ++iter) {
476                 if (seq == iter->spawn_pack) {
477                         iter->spawn_pack = -1;
478                         --confirm_wait;
479                         return;
480                 }
481                 if (seq == iter->despawn_pack) {
482                         spawns.erase(iter);
483                         --confirm_wait;
484                         return;
485                 }
486         }
487 }
488
489 void ClientConnection::OnPacketLost(uint16_t seq) {
490         if (transmitter.Waiting()) {
491                 transmitter.Nack(seq);
492         }
493         if (!confirm_wait) return;
494         for (SpawnStatus &status : spawns) {
495                 if (seq == status.spawn_pack) {
496                         status.spawn_pack = -1;
497                         --confirm_wait;
498                         SendSpawn(status);
499                         return;
500                 }
501                 if (seq == status.despawn_pack) {
502                         status.despawn_pack = -1;
503                         --confirm_wait;
504                         SendDespawn(status);
505                         return;
506                 }
507         }
508 }
509
510 void ClientConnection::On(const Packet::Login &pack) {
511         string name;
512         pack.ReadPlayerName(name);
513
514         Player *new_player = server.JoinPlayer(name);
515
516         if (new_player) {
517                 // success!
518                 AttachPlayer(*new_player);
519                 cout << "accepted login from player \"" << name << '"' << endl;
520                 auto response = Prepare<Packet::Join>();
521                 response.WritePlayer(new_player->GetEntity());
522                 response.WriteWorldName(server.GetWorld().Name());
523                 Send();
524                 // set up update tracking
525                 player_update_state = new_player->GetEntity().GetState();
526                 player_update_pack = pack.Seq();
527                 player_update_timer.Reset();
528                 player_update_timer.Start();
529         } else {
530                 // aw no :(
531                 cout << "rejected login from player \"" << name << '"' << endl;
532                 Prepare<Packet::Part>();
533                 Send();
534                 conn.Close();
535         }
536 }
537
538 void ClientConnection::On(const Packet::Part &) {
539         conn.Close();
540 }
541
542 void ClientConnection::On(const Packet::PlayerUpdate &pack) {
543         if (!HasPlayer()) return;
544         int pack_diff = int16_t(pack.Seq()) - int16_t(player_update_pack);
545         bool overdue = player_update_timer.HitOnce();
546         player_update_timer.Reset();
547         if (pack_diff <= 0 && !overdue) {
548                 // drop old packets if we have a fairly recent state
549                 return;
550         }
551         glm::vec3 movement(0.0f);
552         uint8_t new_actions;
553         uint8_t slot;
554
555         player_update_pack = pack.Seq();
556         pack.ReadPredictedState(player_update_state);
557         pack.ReadMovement(movement);
558         pack.ReadActions(new_actions);
559         pack.ReadSlot(slot);
560
561         input->SetMovement(movement);
562         input->TurnHead(player_update_state.pitch - input->GetPitch(), player_update_state.yaw - input->GetYaw());
563         input->SelectInventory(slot);
564
565         if ((new_actions & 0x01) && !(old_actions & 0x01)) {
566                 input->StartPrimaryAction();
567         } else if (!(new_actions & 0x01) && (old_actions & 0x01)) {
568                 input->StopPrimaryAction();
569         }
570         if ((new_actions & 0x02) && !(old_actions & 0x02)) {
571                 input->StartSecondaryAction();
572         } else if (!(new_actions & 0x02) && (old_actions & 0x02)) {
573                 input->StopSecondaryAction();
574         }
575         if ((new_actions & 0x04) && !(old_actions & 0x04)) {
576                 input->StartTertiaryAction();
577         } else if (!(new_actions & 0x04) && (old_actions & 0x04)) {
578                 input->StopTertiaryAction();
579         }
580         old_actions = new_actions;
581 }
582
583 bool ClientConnection::ChunkInRange(const glm::ivec3 &pos) const noexcept {
584         return HasPlayer() && PlayerChunks().InRange(pos);
585 }
586
587 void ClientConnection::On(const Packet::Message &pack) {
588         uint8_t type;
589         uint32_t ref;
590         string msg;
591         pack.ReadType(type);
592         pack.ReadReferral(ref);
593         pack.ReadMessage(msg);
594
595         if (type == 1 && HasPlayer()) {
596                 server.DispatchMessage(input->GetPlayer(), msg);
597         }
598 }
599
600
601 Server::Server(
602         const Config::Network &conf,
603         World &world,
604         const World::Config &wc,
605         const WorldSave &save)
606 : serv_sock(nullptr)
607 , serv_pack{ -1, nullptr, 0 }
608 , clients()
609 , world(world)
610 , spawn_index(world.Chunks().MakeIndex(wc.spawn, 3))
611 , save(save)
612 , player_model(nullptr)
613 , cli(world) {
614         serv_sock = SDLNet_UDP_Open(conf.port);
615         if (!serv_sock) {
616                 throw NetError("SDLNet_UDP_Open");
617         }
618
619         serv_pack.data = new Uint8[sizeof(Packet)];
620         serv_pack.maxlen = sizeof(Packet);
621 }
622
623 Server::~Server() {
624         world.Chunks().UnregisterIndex(spawn_index);
625         delete[] serv_pack.data;
626         SDLNet_UDP_Close(serv_sock);
627 }
628
629
630 void Server::Handle() {
631         int result = SDLNet_UDP_Recv(serv_sock, &serv_pack);
632         while (result > 0) {
633                 HandlePacket(serv_pack);
634                 result = SDLNet_UDP_Recv(serv_sock, &serv_pack);
635         }
636         if (result == -1) {
637                 // a boo boo happened
638                 throw NetError("SDLNet_UDP_Recv");
639         }
640 }
641
642 void Server::HandlePacket(const UDPpacket &udp_pack) {
643         if (udp_pack.len < int(sizeof(Packet::Header))) {
644                 // packet too small, drop
645                 return;
646         }
647         const Packet &pack = *reinterpret_cast<const Packet *>(udp_pack.data);
648         if (pack.header.tag != Packet::TAG) {
649                 // mistagged packet, drop
650                 return;
651         }
652
653         ClientConnection &client = GetClient(udp_pack.address);
654         client.GetConnection().Received(udp_pack);
655 }
656
657 ClientConnection &Server::GetClient(const IPaddress &addr) {
658         for (ClientConnection &client : clients) {
659                 if (client.Matches(addr)) {
660                         return client;
661                 }
662         }
663         clients.emplace_back(*this, addr);
664         if (HasPlayerModel()) {
665                 clients.back().SetPlayerModel(GetPlayerModel());
666         }
667         return clients.back();
668 }
669
670 void Server::Update(int dt) {
671         for (list<ClientConnection>::iterator client(clients.begin()), end(clients.end()); client != end;) {
672                 client->Update(dt);
673                 if (client->Disconnected()) {
674                         client = clients.erase(client);
675                 } else {
676                         ++client;
677                 }
678         }
679 }
680
681 void Server::SetPlayerModel(const Model &m) noexcept {
682         player_model = &m;
683         for (ClientConnection &client : clients) {
684                 client.SetPlayerModel(m);
685         }
686 }
687
688 bool Server::HasPlayerModel() const noexcept {
689         return player_model;
690 }
691
692 const Model &Server::GetPlayerModel() const noexcept {
693         return *player_model;
694 }
695
696 Player *Server::JoinPlayer(const string &name) {
697         if (spawn_index.MissingChunks() > 0) {
698                 return nullptr;
699         }
700         Player *player = world.AddPlayer(name);
701         if (!player) {
702                 return nullptr;
703         }
704         if (save.Exists(*player)) {
705                 save.Read(*player);
706         } else {
707                 // TODO: spawn
708         }
709         return player;
710 }
711
712 void Server::SetBlock(Chunk &chunk, int index, const Block &block) {
713         chunk.SetBlock(index, block);
714         // TODO: batch chunk changes
715         auto pack = Packet::Make<Packet::BlockUpdate>(GetPacket());
716         pack.WriteChunkCoords(chunk.Position());
717         pack.WriteBlockCount(uint32_t(1));
718         pack.WriteIndex(index, 0);
719         pack.WriteBlock(chunk.BlockAt(index), 0);
720         GetPacket().len = sizeof(Packet::Header) + Packet::BlockUpdate::GetSize(1);
721         for (ClientConnection &client : clients) {
722                 if (client.ChunkInRange(chunk.Position())) {
723                         client.Send();
724                 }
725         }
726 }
727
728 void Server::DispatchMessage(Player &player, const string &msg) {
729         if (msg.empty()) {
730                 return;
731         }
732         if (msg[0] == '/' && msg.size() > 1 && msg[1] != '/') {
733                 cli.Execute(player, msg.substr(1));
734         } else {
735                 DistributeMessage(1, player.GetEntity().ID(), msg);
736         }
737 }
738
739 void Server::DistributeMessage(uint8_t type, uint32_t ref, const string &msg) {
740         auto pack = Packet::Make<Packet::Message>(serv_pack);
741         pack.WriteType(type);
742         pack.WriteReferral(ref);
743         pack.WriteMessage(msg);
744         serv_pack.len = sizeof(Packet::Header) + Packet::Message::GetSize(msg);
745         SendAll();
746 }
747
748 void Server::SendAll() {
749         for (ClientConnection &client : clients) {
750                 client.GetConnection().Send(serv_pack, serv_sock);
751         }
752 }
753
754 }
755 }