src/net/net.cpp

   1 #include "Client.hpp"
   2 #include "ClientConnection.hpp"
   3 #include "Connection.hpp"
   4 #include "ConnectionHandler.hpp"
   5 #include "io.hpp"
   6 #include "Packet.hpp"
   7 #include "Server.hpp"
   8
   9 #include "../app/init.hpp"
  10 #include "../model/CompositeModel.hpp"
  11 #include "../world/Entity.hpp"
  12 #include "../world/EntityState.hpp"
  13 #include "../world/World.hpp"
  14
  15 #include <cstring>
  16 #include <iostream>
  17 #include <glm/gtx/io.hpp>
  18
  19 using namespace std;
  20
  21
  22 namespace blank {
  23
  24 constexpr size_t Packet::Ping::MAX_LEN;
  25 constexpr size_t Packet::Login::MAX_LEN;
  26 constexpr size_t Packet::Join::MAX_LEN;
  27 constexpr size_t Packet::Part::MAX_LEN;
  28 constexpr size_t Packet::PlayerUpdate::MAX_LEN;
  29 constexpr size_t Packet::SpawnEntity::MAX_LEN;
  30 constexpr size_t Packet::DespawnEntity::MAX_LEN;
  31 constexpr size_t Packet::EntityUpdate::MAX_LEN;
  32 constexpr size_t Packet::PlayerCorrection::MAX_LEN;
  33
  34 namespace {
  35
  36 UDPsocket client_bind(Uint16 port) {
  37         UDPsocket sock = SDLNet_UDP_Open(port);
  38         if (!sock) {
  39                 throw NetError("SDLNet_UDP_Open");
  40         }
  41         return sock;
  42 }
  43
  44 IPaddress client_resolve(const char *host, Uint16 port) {
  45         IPaddress addr;
  46         if (SDLNet_ResolveHost(&addr, host, port) != 0) {
  47                 throw NetError("SDLNet_ResolveHost");
  48         }
  49         return addr;
  50 }
  51
  52 }
  53
  54 Client::Client(const Config &conf)
  55 : conn(client_resolve(conf.host.c_str(), conf.port))
  56 , client_sock(client_bind(0))
  57 , client_pack{ -1, nullptr, 0 } {
  58         client_pack.data = new Uint8[sizeof(Packet)];
  59         client_pack.maxlen = sizeof(Packet);
  60         // establish connection
  61         SendPing();
  62 }
  63
  64 Client::~Client() {
  65         delete[] client_pack.data;
  66         SDLNet_UDP_Close(client_sock);
  67 }
  68
  69
  70 void Client::Handle() {
  71         int result = SDLNet_UDP_Recv(client_sock, &client_pack);
  72         while (result > 0) {
  73                 HandlePacket(client_pack);
  74                 result = SDLNet_UDP_Recv(client_sock, &client_pack);
  75         }
  76         if (result == -1) {
  77                 // a boo boo happened
  78                 throw NetError("SDLNet_UDP_Recv");
  79         }
  80 }
  81
  82 void Client::HandlePacket(const UDPpacket &udp_pack) {
  83         if (!conn.Matches(udp_pack.address)) {
  84                 // packet came from somewhere else, drop
  85                 return;
  86         }
  87         const Packet &pack = *reinterpret_cast<const Packet *>(udp_pack.data);
  88         if (pack.header.tag != Packet::TAG) {
  89                 // mistagged packet, drop
  90                 return;
  91         }
  92
  93         conn.Received(udp_pack);
  94 }
  95
  96 void Client::Update(int dt) {
  97         conn.Update(dt);
  98         if (conn.ShouldPing()) {
  99                 SendPing();
 100         }
 101 }
 102
 103 uint16_t Client::SendPing() {
 104         return conn.SendPing(client_pack, client_sock);
 105 }
 106
 107 uint16_t Client::SendLogin(const string &name) {
 108         auto pack = Packet::Make<Packet::Login>(client_pack);
 109         pack.WritePlayerName(name);
 110         return conn.Send(client_pack, client_sock);
 111 }
 112
 113 uint16_t Client::SendPlayerUpdate(const Entity &player) {
 114         auto pack = Packet::Make<Packet::PlayerUpdate>(client_pack);
 115         pack.WritePlayer(player);
 116         return conn.Send(client_pack, client_sock);
 117 }
 118
 119 uint16_t Client::SendPart() {
 120         Packet::Make<Packet::Part>(client_pack);
 121         return conn.Send(client_pack, client_sock);
 122 }
 123
 124
 125 ClientConnection::ClientConnection(Server &server, const IPaddress &addr)
 126 : server(server)
 127 , conn(addr)
 128 , player(nullptr)
 129 , spawns()
 130 , confirm_wait(0)
 131 , player_update_pack(0)
 132 , player_update_timer(1500) {
 133         conn.SetHandler(this);
 134 }
 135
 136 ClientConnection::~ClientConnection() {
 137         DetachPlayer();
 138 }
 139
 140 void ClientConnection::Update(int dt) {
 141         conn.Update(dt);
 142         if (Disconnected()) {
 143                 return;
 144         }
 145         if (HasPlayer()) {
 146                 // sync entities
 147                 auto global_iter = server.GetWorld().Entities().begin();
 148                 auto global_end = server.GetWorld().Entities().end();
 149                 auto local_iter = spawns.begin();
 150                 auto local_end = spawns.end();
 151
 152                 while (global_iter != global_end && local_iter != local_end) {
 153                         if (global_iter->ID() == local_iter->entity->ID()) {
 154                                 // they're the same
 155                                 if (CanDespawn(*global_iter)) {
 156                                         SendDespawn(*local_iter);
 157                                 } else {
 158                                         // update
 159                                         SendUpdate(*local_iter);
 160                                 }
 161                                 ++global_iter;
 162                                 ++local_iter;
 163                         } else if (global_iter->ID() < local_iter->entity->ID()) {
 164                                 // global entity was inserted
 165                                 if (CanSpawn(*global_iter)) {
 166                                         auto spawned = spawns.emplace(local_iter, *global_iter);
 167                                         SendSpawn(*spawned);
 168                                 }
 169                                 ++global_iter;
 170                         } else {
 171                                 // global entity was removed
 172                                 SendDespawn(*local_iter);
 173                                 ++local_iter;
 174                         }
 175                 }
 176
 177                 // leftover spawns
 178                 while (global_iter != global_end) {
 179                         if (CanSpawn(*global_iter)) {
 180                                 spawns.emplace_back(*global_iter);
 181                                 SendSpawn(spawns.back());
 182                         }
 183                         ++global_iter;
 184                 }
 185
 186                 // leftover despawns
 187                 while (local_iter != local_end) {
 188                         SendDespawn(*local_iter);
 189                         ++local_iter;
 190                 }
 191
 192                 CheckPlayerFix();
 193         }
 194         if (conn.ShouldPing()) {
 195                 conn.SendPing(server.GetPacket(), server.GetSocket());
 196         }
 197 }
 198
 199 ClientConnection::SpawnStatus::SpawnStatus(Entity &e)
 200 : entity(&e)
 201 , spawn_pack(-1)
 202 , despawn_pack(-1) {
 203         entity->Ref();
 204 }
 205
 206 ClientConnection::SpawnStatus::~SpawnStatus() {
 207         entity->UnRef();
 208 }
 209
 210 bool ClientConnection::CanSpawn(const Entity &e) const noexcept {
 211         return
 212                 &e != player &&
 213                 !e.Dead() &&
 214                 manhattan_radius(e.ChunkCoords() - Player().ChunkCoords()) < 7;
 215 }
 216
 217 bool ClientConnection::CanDespawn(const Entity &e) const noexcept {
 218         return
 219                 e.Dead() ||
 220                 manhattan_radius(e.ChunkCoords() - Player().ChunkCoords()) > 7;
 221 }
 222
 223 void ClientConnection::SendSpawn(SpawnStatus &status) {
 224         // don't double spawn
 225         if (status.spawn_pack != -1) return;
 226
 227         auto pack = Packet::Make<Packet::SpawnEntity>(server.GetPacket());
 228         pack.WriteEntity(*status.entity);
 229         status.spawn_pack = conn.Send(server.GetPacket(), server.GetSocket());
 230         ++confirm_wait;
 231 }
 232
 233 void ClientConnection::SendDespawn(SpawnStatus &status) {
 234         // don't double despawn
 235         if (status.despawn_pack != -1) return;
 236
 237         auto pack = Packet::Make<Packet::DespawnEntity>(server.GetPacket());
 238         pack.WriteEntityID(status.entity->ID());
 239         status.despawn_pack = conn.Send(server.GetPacket(), server.GetSocket());
 240         ++confirm_wait;
 241 }
 242
 243 void ClientConnection::SendUpdate(SpawnStatus &status) {
 244         // don't send updates while spawn not ack'd or despawn sent
 245         if (status.spawn_pack != -1 || status.despawn_pack != -1) return;
 246
 247         // TODO: pack entity updates
 248         auto pack = Packet::Make<Packet::EntityUpdate>(server.GetPacket());
 249         pack.WriteEntityCount(1);
 250         pack.WriteEntity(*status.entity, 0);
 251         server.GetPacket().len = Packet::EntityUpdate::GetSize(1);
 252         conn.Send(server.GetPacket(), server.GetSocket());
 253 }
 254
 255 void ClientConnection::CheckPlayerFix() {
 256         // check always succeeds for now ;)
 257         auto pack = Packet::Make<Packet::PlayerCorrection>(server.GetPacket());
 258         pack.WritePacketSeq(player_update_pack);
 259         pack.WritePlayer(Player());
 260         conn.Send(server.GetPacket(), server.GetSocket());
 261 }
 262
 263 void ClientConnection::AttachPlayer(Entity &new_player) {
 264         DetachPlayer();
 265         player = &new_player;
 266         player->Ref();
 267         cout << "player \"" << player->Name() << "\" joined" << endl;
 268 }
 269
 270 void ClientConnection::DetachPlayer() {
 271         if (!player) return;
 272         player->Kill();
 273         player->UnRef();
 274         cout << "player \"" << player->Name() << "\" left" << endl;
 275         player = nullptr;
 276 }
 277
 278 void ClientConnection::OnPacketReceived(uint16_t seq) {
 279         if (!confirm_wait) return;
 280         for (auto iter = spawns.begin(), end = spawns.end(); iter != end; ++iter) {
 281                 if (seq == iter->spawn_pack) {
 282                         iter->spawn_pack = -1;
 283                         --confirm_wait;
 284                         return;
 285                 }
 286                 if (seq == iter->despawn_pack) {
 287                         spawns.erase(iter);
 288                         --confirm_wait;
 289                         return;
 290                 }
 291         }
 292 }
 293
 294 void ClientConnection::OnPacketLost(uint16_t seq) {
 295         if (!confirm_wait) return;
 296         for (SpawnStatus &status : spawns) {
 297                 if (seq == status.spawn_pack) {
 298                         status.spawn_pack = -1;
 299                         --confirm_wait;
 300                         SendSpawn(status);
 301                         return;
 302                 }
 303                 if (seq == status.despawn_pack) {
 304                         status.despawn_pack = -1;
 305                         --confirm_wait;
 306                         SendDespawn(status);
 307                         return;
 308                 }
 309         }
 310 }
 311
 312 void ClientConnection::On(const Packet::Login &pack) {
 313         string name;
 314         pack.ReadPlayerName(name);
 315
 316         Entity *new_player = server.GetWorld().AddPlayer(name).entity;
 317
 318         if (new_player) {
 319                 // success!
 320                 AttachPlayer(*new_player);
 321                 cout << "accepted login from player \"" << name << '"' << endl;
 322                 auto response = Packet::Make<Packet::Join>(server.GetPacket());
 323                 response.WritePlayer(*new_player);
 324                 response.WriteWorldName(server.GetWorld().Name());
 325                 conn.Send(server.GetPacket(), server.GetSocket());
 326                 // set up update tracking
 327                 player_update_pack = pack.Seq();
 328                 player_update_timer.Reset();
 329                 player_update_timer.Start();
 330         } else {
 331                 // aw no :(
 332                 cout << "rejected login from player \"" << name << '"' << endl;
 333                 Packet::Make<Packet::Part>(server.GetPacket());
 334                 conn.Send(server.GetPacket(), server.GetSocket());
 335                 conn.Close();
 336         }
 337 }
 338
 339 void ClientConnection::On(const Packet::Part &) {
 340         conn.Close();
 341 }
 342
 343 void ClientConnection::On(const Packet::PlayerUpdate &pack) {
 344         if (!HasPlayer()) return;
 345         int pack_diff = int16_t(pack.Seq()) - int16_t(player_update_pack);
 346         bool overdue = player_update_timer.HitOnce();
 347         player_update_timer.Reset();
 348         if (pack_diff > 0 || overdue) {
 349                 player_update_pack = pack.Seq();
 350                 // TODO: do client input validation here
 351                 pack.ReadPlayerState(Player().GetState());
 352         }
 353 }
 354
 355
 356 Connection::Connection(const IPaddress &addr)
 357 : handler(nullptr)
 358 , addr(addr)
 359 , send_timer(500)
 360 , recv_timer(10000)
 361 , ctrl_out{ 0, 0xFFFF, 0xFFFFFFFF }
 362 , ctrl_in{ 0, 0xFFFF, 0xFFFFFFFF }
 363 , closed(false) {
 364         send_timer.Start();
 365         recv_timer.Start();
 366 }
 367
 368 bool Connection::Matches(const IPaddress &remote) const noexcept {
 369         return memcmp(&addr, &remote, sizeof(IPaddress)) == 0;
 370 }
 371
 372 void Connection::FlagSend() noexcept {
 373         send_timer.Reset();
 374 }
 375
 376 void Connection::FlagRecv() noexcept {
 377         recv_timer.Reset();
 378 }
 379
 380 bool Connection::ShouldPing() const noexcept {
 381         return !closed && send_timer.HitOnce();
 382 }
 383
 384 bool Connection::TimedOut() const noexcept {
 385         return recv_timer.HitOnce();
 386 }
 387
 388 void Connection::Update(int dt) {
 389         send_timer.Update(dt);
 390         recv_timer.Update(dt);
 391         if (TimedOut()) {
 392                 Close();
 393                 if (HasHandler()) {
 394                         Handler().OnTimeout();
 395                 }
 396         }
 397 }
 398
 399
 400 uint16_t Connection::Send(UDPpacket &udp_pack, UDPsocket sock) {
 401         Packet &pack = *reinterpret_cast<Packet *>(udp_pack.data);
 402         pack.header.ctrl = ctrl_out;
 403         uint16_t seq = ctrl_out.seq++;
 404
 405         udp_pack.address = addr;
 406         if (SDLNet_UDP_Send(sock, -1, &udp_pack) == 0) {
 407                 throw NetError("SDLNet_UDP_Send");
 408         }
 409
 410         FlagSend();
 411         return seq;
 412 }
 413
 414 void Connection::Received(const UDPpacket &udp_pack) {
 415         Packet &pack = *reinterpret_cast<Packet *>(udp_pack.data);
 416
 417         // ack to the remote
 418         int16_t diff = int16_t(pack.header.ctrl.seq) - int16_t(ctrl_out.ack);
 419         if (diff > 0) {
 420                 if (diff >= 32) {
 421                         ctrl_out.hist = 0;
 422                 } else {
 423                         ctrl_out.hist <<= diff;
 424                         ctrl_out.hist |= 1 << (diff - 1);
 425                 }
 426         } else if (diff < 0 && diff >= -32) {
 427                 ctrl_out.hist |= 1 << (-diff - 1);
 428         }
 429         ctrl_out.ack = pack.header.ctrl.seq;
 430         FlagRecv();
 431
 432         if (!HasHandler()) {
 433                 return;
 434         }
 435
 436         Packet::TControl ctrl_new = pack.header.ctrl;
 437         Handler().Handle(udp_pack);
 438
 439         if (diff > 0) {
 440                 // if the packet holds more recent information
 441                 // check if remote failed to ack one of our packets
 442                 diff = int16_t(ctrl_new.ack) - int16_t(ctrl_in.ack);
 443                 // should always be true, but you never know…
 444                 if (diff > 0) {
 445                         for (int i = 0; i < diff; ++i) {
 446                                 if (i > 32 || (i < 32 && (ctrl_in.hist & (1 << (31 - i))) == 0)) {
 447                                         Handler().OnPacketLost(ctrl_in.ack - 32 + i);
 448                                 }
 449                         }
 450                 }
 451                 // check for newly ack'd packets
 452                 for (uint16_t s = ctrl_new.AckBegin(); s != ctrl_new.AckEnd(); ++s) {
 453                         if (ctrl_new.Acks(s) && !ctrl_in.Acks(s)) {
 454                                 Handler().OnPacketReceived(s);
 455                         }
 456                 }
 457                 ctrl_in = ctrl_new;
 458         }
 459 }
 460
 461 bool Packet::TControl::Acks(uint16_t s) const noexcept {
 462         int16_t diff = int16_t(ack) - int16_t(s);
 463         if (diff == 0) return true;
 464         if (diff < 0 || diff > 32) return false;
 465         return (hist & (1 << (diff - 1))) != 0;
 466 }
 467
 468 uint16_t Connection::SendPing(UDPpacket &udp_pack, UDPsocket sock) {
 469         Packet::Make<Packet::Ping>(udp_pack);
 470         return Send(udp_pack, sock);
 471 }
 472
 473
 474 ostream &operator <<(ostream &out, const IPaddress &addr) {
 475         const unsigned char *host = reinterpret_cast<const unsigned char *>(&addr.host);
 476         out << int(host[0])
 477                 << '.' << int(host[1])
 478                 << '.' << int(host[2])
 479                 << '.' << int(host[3]);
 480         if (addr.port) {
 481                 out << ':' << SDLNet_Read16(&addr.port);
 482         }
 483         return out;
 484 }
 485
 486
 487 const char *Packet::Type2String(uint8_t t) noexcept {
 488         switch (t) {
 489                 case Ping::TYPE:
 490                         return "Ping";
 491                 case Login::TYPE:
 492                         return "Login";
 493                 case Join::TYPE:
 494                         return "Join";
 495                 case Part::TYPE:
 496                         return "Part";
 497                 case PlayerUpdate::TYPE:
 498                         return "PlayerUpdate";
 499                 case SpawnEntity::TYPE:
 500                         return "SpawnEntity";
 501                 case DespawnEntity::TYPE:
 502                         return "DespawnEntity";
 503                 case EntityUpdate::TYPE:
 504                         return "EntityUpdate";
 505                 case PlayerCorrection::TYPE:
 506                         return "PlayerCorrection";
 507                 default:
 508                         return "Unknown";
 509         }
 510 }
 511
 512 template<class T>
 513 void Packet::Payload::Write(const T &src, size_t off) noexcept {
 514         if ((length - off) < sizeof(T)) {
 515                 // dismiss out of bounds write
 516                 return;
 517         }
 518         *reinterpret_cast<T *>(&data[off]) = src;
 519 }
 520
 521 template<class T>
 522 void Packet::Payload::Read(T &dst, size_t off) const noexcept {
 523         if ((length - off) < sizeof(T)) {
 524                 // dismiss out of bounds read
 525                 return;
 526         }
 527         dst = *reinterpret_cast<T *>(&data[off]);
 528 }
 529
 530 void Packet::Payload::WriteString(const string &src, size_t off, size_t maxlen) noexcept {
 531         uint8_t *dst = &data[off];
 532         size_t len = min(maxlen, length - off);
 533         if (src.size() < len) {
 534                 memset(dst, '\0', len);
 535                 memcpy(dst, src.c_str(), src.size());
 536         } else {
 537                 memcpy(dst, src.c_str(), len);
 538         }
 539 }
 540
 541 void Packet::Payload::ReadString(string &dst, size_t off, size_t maxlen) const noexcept {
 542         size_t len = min(maxlen, length - off);
 543         dst.clear();
 544         dst.reserve(len);
 545         for (size_t i = 0; i < len && data[off + i] != '\0'; ++i) {
 546                 dst.push_back(data[off + i]);
 547         }
 548 }
 549
 550
 551 void Packet::Login::WritePlayerName(const string &name) noexcept {
 552         WriteString(name, 0, 32);
 553 }
 554
 555 void Packet::Login::ReadPlayerName(string &name) const noexcept {
 556         ReadString(name, 0, 32);
 557 }
 558
 559 void Packet::Join::WritePlayer(const Entity &player) noexcept {
 560         Write(player.ID(), 0);
 561         Write(player.GetState(), 4);
 562 }
 563
 564 void Packet::Join::ReadPlayerID(uint32_t &id) const noexcept {
 565         Read(id, 0);
 566 }
 567
 568 void Packet::Join::ReadPlayerState(EntityState &state) const noexcept {
 569         Read(state, 4);
 570 }
 571
 572 void Packet::Join::WriteWorldName(const string &name) noexcept {
 573         WriteString(name, 68, 32);
 574 }
 575
 576 void Packet::Join::ReadWorldName(string &name) const noexcept {
 577         ReadString(name, 68, 32);
 578 }
 579
 580 void Packet::PlayerUpdate::WritePlayer(const Entity &player) noexcept {
 581         Write(player.GetState(), 0);
 582 }
 583
 584 void Packet::PlayerUpdate::ReadPlayerState(EntityState &state) const noexcept {
 585         Read(state, 0);
 586 }
 587
 588 void Packet::SpawnEntity::WriteEntity(const Entity &e) noexcept {
 589         Write(e.ID(), 0);
 590         if (e.GetModel()) {
 591                 Write(e.GetModel().GetModel().ID(), 4);
 592         } else {
 593                 Write(uint32_t(0), 4);
 594         }
 595         Write(e.GetState(), 8);
 596         Write(e.Bounds(), 72);
 597         uint32_t flags = 0;
 598         if (e.WorldCollidable()) {
 599                 flags |= 1;
 600         }
 601         Write(flags, 96);
 602         WriteString(e.Name(), 100, 32);
 603 }
 604
 605 void Packet::SpawnEntity::ReadEntityID(uint32_t &id) const noexcept {
 606         Read(id, 0);
 607 }
 608
 609 void Packet::SpawnEntity::ReadSkeletonID(uint32_t &id) const noexcept {
 610         Read(id, 4);
 611 }
 612
 613 void Packet::SpawnEntity::ReadEntity(Entity &e) const noexcept {
 614         EntityState state;
 615         AABB bounds;
 616         uint32_t flags = 0;
 617         string name;
 618
 619         Read(state, 8);
 620         Read(bounds, 72);
 621         Read(flags, 96);
 622         ReadString(name, 100, 32);
 623
 624         e.SetState(state);
 625         e.Bounds(bounds);
 626         e.WorldCollidable(flags & 1);
 627         e.Name(name);
 628 }
 629
 630 void Packet::DespawnEntity::WriteEntityID(uint32_t id) noexcept {
 631         Write(id, 0);
 632 }
 633
 634 void Packet::DespawnEntity::ReadEntityID(uint32_t &id) const noexcept {
 635         Read(id, 0);
 636 }
 637
 638 void Packet::EntityUpdate::WriteEntityCount(uint32_t count) noexcept {
 639         Write(count, 0);
 640 }
 641
 642 void Packet::EntityUpdate::ReadEntityCount(uint32_t &count) const noexcept {
 643         Read(count, 0);
 644 }
 645
 646 void Packet::EntityUpdate::WriteEntity(const Entity &entity, uint32_t num) noexcept {
 647         uint32_t off = 4 + (num * 64);
 648
 649         Write(entity.ID(), off);
 650         Write(entity.GetState(), off + 4);
 651 }
 652
 653 void Packet::EntityUpdate::ReadEntityID(uint32_t &id, uint32_t num) const noexcept {
 654         Read(id, 4 + (num * 64));
 655 }
 656
 657 void Packet::EntityUpdate::ReadEntityState(EntityState &state, uint32_t num) const noexcept {
 658         uint32_t off = 4 + (num * 64);
 659         Read(state, off + 4);
 660 }
 661
 662 void Packet::PlayerCorrection::WritePacketSeq(std::uint16_t s) noexcept {
 663         Write(s, 0);
 664 }
 665
 666 void Packet::PlayerCorrection::ReadPacketSeq(std::uint16_t &s) const noexcept {
 667         Read(s, 0);
 668 }
 669
 670 void Packet::PlayerCorrection::WritePlayer(const Entity &player) noexcept {
 671         Write(player.GetState(), 2);
 672 }
 673
 674 void Packet::PlayerCorrection::ReadPlayerState(EntityState &state) const noexcept {
 675         Read(state, 2);
 676 }
 677
 678
 679 void ConnectionHandler::Handle(const UDPpacket &udp_pack) {
 680         const Packet &pack = *reinterpret_cast<const Packet *>(udp_pack.data);
 681         switch (pack.Type()) {
 682                 case Packet::Ping::TYPE:
 683                         On(Packet::As<Packet::Ping>(udp_pack));
 684                         break;
 685                 case Packet::Login::TYPE:
 686                         On(Packet::As<Packet::Login>(udp_pack));
 687                         break;
 688                 case Packet::Join::TYPE:
 689                         On(Packet::As<Packet::Join>(udp_pack));
 690                         break;
 691                 case Packet::Part::TYPE:
 692                         On(Packet::As<Packet::Part>(udp_pack));
 693                         break;
 694                 case Packet::PlayerUpdate::TYPE:
 695                         On(Packet::As<Packet::PlayerUpdate>(udp_pack));
 696                         break;
 697                 case Packet::SpawnEntity::TYPE:
 698                         On(Packet::As<Packet::SpawnEntity>(udp_pack));
 699                         break;
 700                 case Packet::DespawnEntity::TYPE:
 701                         On(Packet::As<Packet::DespawnEntity>(udp_pack));
 702                         break;
 703                 case Packet::EntityUpdate::TYPE:
 704                         On(Packet::As<Packet::EntityUpdate>(udp_pack));
 705                         break;
 706                 case Packet::PlayerCorrection::TYPE:
 707                         On(Packet::As<Packet::PlayerCorrection>(udp_pack));
 708                         break;
 709                 default:
 710                         // drop unknown or unhandled packets
 711                         break;
 712         }
 713 }
 714
 715
 716 Server::Server(const Config &conf, World &world)
 717 : serv_sock(nullptr)
 718 , serv_pack{ -1, nullptr, 0 }
 719 , clients()
 720 , world(world) {
 721         serv_sock = SDLNet_UDP_Open(conf.port);
 722         if (!serv_sock) {
 723                 throw NetError("SDLNet_UDP_Open");
 724         }
 725
 726         serv_pack.data = new Uint8[sizeof(Packet)];
 727         serv_pack.maxlen = sizeof(Packet);
 728 }
 729
 730 Server::~Server() {
 731         delete[] serv_pack.data;
 732         SDLNet_UDP_Close(serv_sock);
 733 }
 734
 735
 736 void Server::Handle() {
 737         int result = SDLNet_UDP_Recv(serv_sock, &serv_pack);
 738         while (result > 0) {
 739                 HandlePacket(serv_pack);
 740                 result = SDLNet_UDP_Recv(serv_sock, &serv_pack);
 741         }
 742         if (result == -1) {
 743                 // a boo boo happened
 744                 throw NetError("SDLNet_UDP_Recv");
 745         }
 746 }
 747
 748 void Server::HandlePacket(const UDPpacket &udp_pack) {
 749         if (udp_pack.len < int(sizeof(Packet::Header))) {
 750                 // packet too small, drop
 751                 return;
 752         }
 753         const Packet &pack = *reinterpret_cast<const Packet *>(udp_pack.data);
 754         if (pack.header.tag != Packet::TAG) {
 755                 // mistagged packet, drop
 756                 return;
 757         }
 758
 759         ClientConnection &client = GetClient(udp_pack.address);
 760         client.GetConnection().Received(udp_pack);
 761 }
 762
 763 ClientConnection &Server::GetClient(const IPaddress &addr) {
 764         for (ClientConnection &client : clients) {
 765                 if (client.Matches(addr)) {
 766                         return client;
 767                 }
 768         }
 769         clients.emplace_back(*this, addr);
 770         return clients.back();
 771 }
 772
 773 void Server::Update(int dt) {
 774         for (list<ClientConnection>::iterator client(clients.begin()), end(clients.end()); client != end;) {
 775                 client->Update(dt);
 776                 if (client->Disconnected()) {
 777                         client = clients.erase(client);
 778                 } else {
 779                         ++client;
 780                 }
 781         }
 782 }
 783
 784 }