git.r.bdr.sh - rbdr/mobius/blob - hotline/server.go

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "bytes"
   6         "context"
   7         "encoding/binary"
   8         "errors"
   9         "fmt"
  10         "github.com/go-playground/validator/v10"
  11         "go.uber.org/zap"
  12         "gopkg.in/yaml.v3"
  13         "io"
  14         "io/fs"
  15         "io/ioutil"
  16         "math/big"
  17         "math/rand"
  18         "net"
  19         "os"
  20         "path/filepath"
  21         "strings"
  22         "sync"
  23         "time"
  24 )
  25
  26 type contextKey string
  27
  28 var contextKeyReq = contextKey("req")
  29
  30 type requestCtx struct {
  31         remoteAddr string
  32         login      string
  33         name       string
  34 }
  35
  36 const (
  37         userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
  38         idleCheckInterval      = 10  // time in seconds to check for idle users
  39         trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
  40 )
  41
  42 var nostalgiaVersion = []byte{0, 0, 2, 0x2c} // version ID used by the Nostalgia client
  43
  44 type Server struct {
  45         Port          int
  46         Accounts      map[string]*Account
  47         Agreement     []byte
  48         Clients       map[uint16]*ClientConn
  49         fileTransfers map[[4]byte]*FileTransfer
  50
  51         Config    *Config
  52         ConfigDir string
  53         Logger    *zap.SugaredLogger
  54
  55         PrivateChatsMu sync.Mutex
  56         PrivateChats   map[uint32]*PrivateChat
  57
  58         NextGuestID   *uint16
  59         TrackerPassID [4]byte
  60
  61         StatsMu sync.Mutex
  62         Stats   *Stats
  63
  64         FS FileStore // Storage backend to use for File storage
  65
  66         outbox chan Transaction
  67         mux    sync.Mutex
  68
  69         threadedNewsMux sync.Mutex
  70         ThreadedNews    *ThreadedNews
  71
  72         flatNewsMux sync.Mutex
  73         FlatNews    []byte
  74
  75         banListMU sync.Mutex
  76         banList   map[string]*time.Time
  77 }
  78
  79 func (s *Server) CurrentStats() Stats {
  80         s.StatsMu.Lock()
  81         defer s.StatsMu.Unlock()
  82
  83         stats := s.Stats
  84         stats.CurrentlyConnected = len(s.Clients)
  85
  86         return *stats
  87 }
  88
  89 type PrivateChat struct {
  90         Subject    string
  91         ClientConn map[uint16]*ClientConn
  92 }
  93
  94 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  95         s.Logger.Infow("Hotline server started",
  96                 "version", VERSION,
  97                 "API port", fmt.Sprintf(":%v", s.Port),
  98                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  99         )
 100
 101         var wg sync.WaitGroup
 102
 103         wg.Add(1)
 104         go func() {
 105                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
 106                 if err != nil {
 107                         s.Logger.Fatal(err)
 108                 }
 109
 110                 s.Logger.Fatal(s.Serve(ctx, ln))
 111         }()
 112
 113         wg.Add(1)
 114         go func() {
 115                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
 116                 if err != nil {
 117                         s.Logger.Fatal(err)
 118
 119                 }
 120
 121                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 122         }()
 123
 124         wg.Wait()
 125
 126         return nil
 127 }
 128
 129 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 130         for {
 131                 conn, err := ln.Accept()
 132                 if err != nil {
 133                         return err
 134                 }
 135
 136                 go func() {
 137                         defer func() { _ = conn.Close() }()
 138
 139                         err = s.handleFileTransfer(
 140                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 141                                         remoteAddr: conn.RemoteAddr().String(),
 142                                 }),
 143                                 conn,
 144                         )
 145
 146                         if err != nil {
 147                                 s.Logger.Errorw("file transfer error", "reason", err)
 148                         }
 149                 }()
 150         }
 151 }
 152
 153 func (s *Server) sendTransaction(t Transaction) error {
 154         clientID, err := byteToInt(*t.clientID)
 155         if err != nil {
 156                 return err
 157         }
 158
 159         s.mux.Lock()
 160         client := s.Clients[uint16(clientID)]
 161         if client == nil {
 162                 return fmt.Errorf("invalid client id %v", *t.clientID)
 163         }
 164
 165         s.mux.Unlock()
 166
 167         b, err := t.MarshalBinary()
 168         if err != nil {
 169                 return err
 170         }
 171
 172         if _, err := client.Connection.Write(b); err != nil {
 173                 return err
 174         }
 175
 176         return nil
 177 }
 178
 179 func (s *Server) processOutbox() {
 180         for {
 181                 t := <-s.outbox
 182                 go func() {
 183                         if err := s.sendTransaction(t); err != nil {
 184                                 s.Logger.Errorw("error sending transaction", "err", err)
 185                         }
 186                 }()
 187         }
 188 }
 189
 190 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 191         go s.processOutbox()
 192
 193         for {
 194                 conn, err := ln.Accept()
 195                 if err != nil {
 196                         s.Logger.Errorw("error accepting connection", "err", err)
 197                 }
 198                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 199                         remoteAddr: conn.RemoteAddr().String(),
 200                 })
 201
 202                 go func() {
 203                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 204
 205                         defer conn.Close()
 206                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 207                                 if err == io.EOF {
 208                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 209                                 } else {
 210                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 211                                 }
 212                         }
 213                 }()
 214         }
 215 }
 216
 217 const (
 218         agreementFile = "Agreement.txt"
 219 )
 220
 221 // NewServer constructs a new Server from a config dir
 222 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 223         server := Server{
 224                 Port:          netPort,
 225                 Accounts:      make(map[string]*Account),
 226                 Config:        new(Config),
 227                 Clients:       make(map[uint16]*ClientConn),
 228                 fileTransfers: make(map[[4]byte]*FileTransfer),
 229                 PrivateChats:  make(map[uint32]*PrivateChat),
 230                 ConfigDir:     configDir,
 231                 Logger:        logger,
 232                 NextGuestID:   new(uint16),
 233                 outbox:        make(chan Transaction),
 234                 Stats:         &Stats{Since: time.Now()},
 235                 ThreadedNews:  &ThreadedNews{},
 236                 FS:            FS,
 237                 banList:       make(map[string]*time.Time),
 238         }
 239
 240         var err error
 241
 242         // generate a new random passID for tracker registration
 243         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 244                 return nil, err
 245         }
 246
 247         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 248         if err != nil {
 249                 return nil, err
 250         }
 251
 252         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 253                 return nil, err
 254         }
 255
 256         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 257         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 258
 259         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 260                 return nil, err
 261         }
 262
 263         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 264                 return nil, err
 265         }
 266
 267         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 268                 return nil, err
 269         }
 270
 271         server.Config.FileRoot = filepath.Join(configDir, "Files")
 272
 273         *server.NextGuestID = 1
 274
 275         if server.Config.EnableTrackerRegistration {
 276                 server.Logger.Infow(
 277                         "Tracker registration enabled",
 278                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 279                         "trackers", server.Config.Trackers,
 280                 )
 281
 282                 go func() {
 283                         for {
 284                                 tr := &TrackerRegistration{
 285                                         UserCount:   server.userCount(),
 286                                         PassID:      server.TrackerPassID[:],
 287                                         Name:        server.Config.Name,
 288                                         Description: server.Config.Description,
 289                                 }
 290                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 291                                 for _, t := range server.Config.Trackers {
 292                                         if err := register(t, tr); err != nil {
 293                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 294                                         }
 295                                         server.Logger.Debugw("Sent Tracker registration", "addr", t)
 296                                 }
 297
 298                                 time.Sleep(trackerUpdateFrequency * time.Second)
 299                         }
 300                 }()
 301         }
 302
 303         // Start Client Keepalive go routine
 304         go server.keepaliveHandler()
 305
 306         return &server, nil
 307 }
 308
 309 func (s *Server) userCount() int {
 310         s.mux.Lock()
 311         defer s.mux.Unlock()
 312
 313         return len(s.Clients)
 314 }
 315
 316 func (s *Server) keepaliveHandler() {
 317         for {
 318                 time.Sleep(idleCheckInterval * time.Second)
 319                 s.mux.Lock()
 320
 321                 for _, c := range s.Clients {
 322                         c.IdleTime += idleCheckInterval
 323                         if c.IdleTime > userIdleSeconds && !c.Idle {
 324                                 c.Idle = true
 325
 326                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 327                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 328                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 329
 330                                 c.sendAll(
 331                                         tranNotifyChangeUser,
 332                                         NewField(fieldUserID, *c.ID),
 333                                         NewField(fieldUserFlags, c.Flags),
 334                                         NewField(fieldUserName, c.UserName),
 335                                         NewField(fieldUserIconID, c.Icon),
 336                                 )
 337                         }
 338                 }
 339                 s.mux.Unlock()
 340         }
 341 }
 342
 343 func (s *Server) writeBanList() error {
 344         s.banListMU.Lock()
 345         defer s.banListMU.Unlock()
 346
 347         out, err := yaml.Marshal(s.banList)
 348         if err != nil {
 349                 return err
 350         }
 351         err = ioutil.WriteFile(
 352                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 353                 out,
 354                 0666,
 355         )
 356         return err
 357 }
 358
 359 func (s *Server) writeThreadedNews() error {
 360         s.threadedNewsMux.Lock()
 361         defer s.threadedNewsMux.Unlock()
 362
 363         out, err := yaml.Marshal(s.ThreadedNews)
 364         if err != nil {
 365                 return err
 366         }
 367         err = s.FS.WriteFile(
 368                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 369                 out,
 370                 0666,
 371         )
 372         return err
 373 }
 374
 375 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 376         s.mux.Lock()
 377         defer s.mux.Unlock()
 378
 379         clientConn := &ClientConn{
 380                 ID:         &[]byte{0, 0},
 381                 Icon:       []byte{0, 0},
 382                 Flags:      []byte{0, 0},
 383                 UserName:   []byte{},
 384                 Connection: conn,
 385                 Server:     s,
 386                 Version:    []byte{},
 387                 AutoReply:  []byte{},
 388                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 389                 Agreed:     false,
 390                 RemoteAddr: remoteAddr,
 391         }
 392         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 393                 FileDownload:   {},
 394                 FileUpload:     {},
 395                 FolderDownload: {},
 396                 FolderUpload:   {},
 397                 bannerDownload: {},
 398         }
 399
 400         *s.NextGuestID++
 401         ID := *s.NextGuestID
 402
 403         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 404         s.Clients[ID] = clientConn
 405
 406         return clientConn
 407 }
 408
 409 // NewUser creates a new user account entry in the server map and config file
 410 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 411         s.mux.Lock()
 412         defer s.mux.Unlock()
 413
 414         account := Account{
 415                 Login:    login,
 416                 Name:     name,
 417                 Password: hashAndSalt([]byte(password)),
 418                 Access:   access,
 419         }
 420         out, err := yaml.Marshal(&account)
 421         if err != nil {
 422                 return err
 423         }
 424         s.Accounts[login] = &account
 425
 426         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 427 }
 428
 429 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 430         s.mux.Lock()
 431         defer s.mux.Unlock()
 432
 433         // update renames the user login
 434         if login != newLogin {
 435                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 436                 if err != nil {
 437                         return err
 438                 }
 439                 s.Accounts[newLogin] = s.Accounts[login]
 440                 delete(s.Accounts, login)
 441         }
 442
 443         account := s.Accounts[newLogin]
 444         account.Access = access
 445         account.Name = name
 446         account.Password = password
 447
 448         out, err := yaml.Marshal(&account)
 449         if err != nil {
 450                 return err
 451         }
 452
 453         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 454                 return err
 455         }
 456
 457         return nil
 458 }
 459
 460 // DeleteUser deletes the user account
 461 func (s *Server) DeleteUser(login string) error {
 462         s.mux.Lock()
 463         defer s.mux.Unlock()
 464
 465         delete(s.Accounts, login)
 466
 467         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 468 }
 469
 470 func (s *Server) connectedUsers() []Field {
 471         s.mux.Lock()
 472         defer s.mux.Unlock()
 473
 474         var connectedUsers []Field
 475         for _, c := range sortedClients(s.Clients) {
 476                 if !c.Agreed {
 477                         continue
 478                 }
 479                 user := User{
 480                         ID:    *c.ID,
 481                         Icon:  c.Icon,
 482                         Flags: c.Flags,
 483                         Name:  string(c.UserName),
 484                 }
 485                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 486         }
 487         return connectedUsers
 488 }
 489
 490 func (s *Server) loadBanList(path string) error {
 491         fh, err := os.Open(path)
 492         if err != nil {
 493                 return err
 494         }
 495         decoder := yaml.NewDecoder(fh)
 496
 497         return decoder.Decode(s.banList)
 498 }
 499
 500 // loadThreadedNews loads the threaded news data from disk
 501 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 502         fh, err := os.Open(threadedNewsPath)
 503         if err != nil {
 504                 return err
 505         }
 506         decoder := yaml.NewDecoder(fh)
 507
 508         return decoder.Decode(s.ThreadedNews)
 509 }
 510
 511 // loadAccounts loads account data from disk
 512 func (s *Server) loadAccounts(userDir string) error {
 513         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 514         if err != nil {
 515                 return err
 516         }
 517
 518         if len(matches) == 0 {
 519                 return errors.New("no user accounts found in " + userDir)
 520         }
 521
 522         for _, file := range matches {
 523                 fh, err := s.FS.Open(file)
 524                 if err != nil {
 525                         return err
 526                 }
 527
 528                 account := Account{}
 529                 decoder := yaml.NewDecoder(fh)
 530                 if err := decoder.Decode(&account); err != nil {
 531                         return err
 532                 }
 533
 534                 s.Accounts[account.Login] = &account
 535         }
 536         return nil
 537 }
 538
 539 func (s *Server) loadConfig(path string) error {
 540         fh, err := s.FS.Open(path)
 541         if err != nil {
 542                 return err
 543         }
 544
 545         decoder := yaml.NewDecoder(fh)
 546         err = decoder.Decode(s.Config)
 547         if err != nil {
 548                 return err
 549         }
 550
 551         validate := validator.New()
 552         err = validate.Struct(s.Config)
 553         if err != nil {
 554                 return err
 555         }
 556         return nil
 557 }
 558
 559 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 560 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 561         defer dontPanic(s.Logger)
 562
 563         if err := Handshake(rwc); err != nil {
 564                 return err
 565         }
 566
 567         // Create a new scanner for parsing incoming bytes into transaction tokens
 568         scanner := bufio.NewScanner(rwc)
 569         scanner.Split(transactionScanner)
 570
 571         scanner.Scan()
 572
 573         var clientLogin Transaction
 574         if _, err := clientLogin.Write(scanner.Bytes()); err != nil {
 575                 return err
 576         }
 577
 578         c := s.NewClientConn(rwc, remoteAddr)
 579
 580         // check if remoteAddr is present in the ban list
 581         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 582                 // permaban
 583                 if banUntil == nil {
 584                         s.outbox <- *NewTransaction(
 585                                 tranServerMsg,
 586                                 c.ID,
 587                                 NewField(fieldData, []byte("You are permanently banned on this server")),
 588                                 NewField(fieldChatOptions, []byte{0, 0}),
 589                         )
 590                         time.Sleep(1 * time.Second)
 591                         return nil
 592                 } else if time.Now().Before(*banUntil) {
 593                         s.outbox <- *NewTransaction(
 594                                 tranServerMsg,
 595                                 c.ID,
 596                                 NewField(fieldData, []byte("You are temporarily banned on this server")),
 597                                 NewField(fieldChatOptions, []byte{0, 0}),
 598                         )
 599                         time.Sleep(1 * time.Second)
 600                         return nil
 601                 }
 602
 603         }
 604         defer c.Disconnect()
 605
 606         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 607         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 608         c.Version = clientLogin.GetField(fieldVersion).Data
 609
 610         var login string
 611         for _, char := range encodedLogin {
 612                 login += string(rune(255 - uint(char)))
 613         }
 614         if login == "" {
 615                 login = GuestAccount
 616         }
 617
 618         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 619
 620         // If authentication fails, send error reply and close connection
 621         if !c.Authenticate(login, encodedPassword) {
 622                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 623                 b, err := t.MarshalBinary()
 624                 if err != nil {
 625                         return err
 626                 }
 627                 if _, err := rwc.Write(b); err != nil {
 628                         return err
 629                 }
 630
 631                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 632
 633                 return nil
 634         }
 635
 636         if clientLogin.GetField(fieldUserIconID).Data != nil {
 637                 c.Icon = clientLogin.GetField(fieldUserIconID).Data
 638         }
 639
 640         c.Account = c.Server.Accounts[login]
 641
 642         if clientLogin.GetField(fieldUserName).Data != nil {
 643                 if c.Authorize(accessAnyName) {
 644                         c.UserName = clientLogin.GetField(fieldUserName).Data
 645                 } else {
 646                         c.UserName = []byte(c.Account.Name)
 647                 }
 648         }
 649
 650         if c.Authorize(accessDisconUser) {
 651                 c.Flags = []byte{0, 2}
 652         }
 653
 654         s.outbox <- c.NewReply(&clientLogin,
 655                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 656                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 657                 NewField(fieldServerName, []byte(s.Config.Name)),
 658         )
 659
 660         // Send user access privs so client UI knows how to behave
 661         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, c.Account.Access[:]))
 662
 663         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 664         // client versions.  For 1.2.3 client, we do not send tranShowAgreement.  For other client versions, we send
 665         // tranShowAgreement but with the NoServerAgreement field set to 1.
 666         if c.Authorize(accessNoAgreement) {
 667                 // If client version is nil, then the client uses the 1.2.3 login behavior
 668                 if c.Version != nil {
 669                         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldNoServerAgreement, []byte{1}))
 670                 }
 671         } else {
 672                 c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 673         }
 674
 675         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 676         if c.Version == nil || bytes.Equal(c.Version, nostalgiaVersion) {
 677                 c.Agreed = true
 678                 c.logger = c.logger.With("name", string(c.UserName))
 679                 c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(c.Version); return i }()))
 680
 681                 for _, t := range c.notifyOthers(
 682                         *NewTransaction(
 683                                 tranNotifyChangeUser, nil,
 684                                 NewField(fieldUserName, c.UserName),
 685                                 NewField(fieldUserID, *c.ID),
 686                                 NewField(fieldUserIconID, c.Icon),
 687                                 NewField(fieldUserFlags, c.Flags),
 688                         ),
 689                 ) {
 690                         c.Server.outbox <- t
 691                 }
 692         }
 693
 694         c.Server.Stats.ConnectionCounter += 1
 695         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 696                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 697         }
 698
 699         // Scan for new transactions and handle them as they come in.
 700         for scanner.Scan() {
 701                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 702                 // scanner re-uses the buffer for subsequent scans.
 703                 buf := make([]byte, len(scanner.Bytes()))
 704                 copy(buf, scanner.Bytes())
 705
 706                 var t Transaction
 707                 if _, err := t.Write(buf); err != nil {
 708                         return err
 709                 }
 710
 711                 if err := c.handleTransaction(t); err != nil {
 712                         c.logger.Errorw("Error handling transaction", "err", err)
 713                 }
 714         }
 715         return nil
 716 }
 717
 718 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 719         s.PrivateChatsMu.Lock()
 720         defer s.PrivateChatsMu.Unlock()
 721
 722         randID := make([]byte, 4)
 723         rand.Read(randID)
 724         data := binary.BigEndian.Uint32(randID[:])
 725
 726         s.PrivateChats[data] = &PrivateChat{
 727                 ClientConn: make(map[uint16]*ClientConn),
 728         }
 729         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 730
 731         return randID
 732 }
 733
 734 const dlFldrActionSendFile = 1
 735 const dlFldrActionResumeFile = 2
 736 const dlFldrActionNextFile = 3
 737
 738 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 739 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 740         defer dontPanic(s.Logger)
 741
 742         txBuf := make([]byte, 16)
 743         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 744                 return err
 745         }
 746
 747         var t transfer
 748         if _, err := t.Write(txBuf); err != nil {
 749                 return err
 750         }
 751
 752         defer func() {
 753                 s.mux.Lock()
 754                 delete(s.fileTransfers, t.ReferenceNumber)
 755                 s.mux.Unlock()
 756
 757         }()
 758
 759         s.mux.Lock()
 760         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 761         s.mux.Unlock()
 762         if !ok {
 763                 return errors.New("invalid transaction ID")
 764         }
 765
 766         defer func() {
 767                 fileTransfer.ClientConn.transfersMU.Lock()
 768                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 769                 fileTransfer.ClientConn.transfersMU.Unlock()
 770         }()
 771
 772         rLogger := s.Logger.With(
 773                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 774                 "login", fileTransfer.ClientConn.Account.Login,
 775                 "name", string(fileTransfer.ClientConn.UserName),
 776         )
 777
 778         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 779         if err != nil {
 780                 return err
 781         }
 782
 783         switch fileTransfer.Type {
 784         case bannerDownload:
 785                 if err := s.bannerDownload(rwc); err != nil {
 786                         return err
 787                 }
 788         case FileDownload:
 789                 s.Stats.DownloadCounter += 1
 790                 s.Stats.DownloadsInProgress += 1
 791                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 792
 793                 var dataOffset int64
 794                 if fileTransfer.fileResumeData != nil {
 795                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 796                 }
 797
 798                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 799                 if err != nil {
 800                         return err
 801                 }
 802
 803                 rLogger.Infow("File download started", "filePath", fullPath)
 804
 805                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 806                 if fileTransfer.options == nil {
 807                         // Start by sending flat file object to client
 808                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 809                                 return err
 810                         }
 811                 }
 812
 813                 file, err := fw.dataForkReader()
 814                 if err != nil {
 815                         return err
 816                 }
 817
 818                 br := bufio.NewReader(file)
 819                 if _, err := br.Discard(int(dataOffset)); err != nil {
 820                         return err
 821                 }
 822
 823                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 824                         return err
 825                 }
 826
 827                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 828                 if fileTransfer.fileResumeData == nil {
 829                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 830                         if err != nil {
 831                                 return err
 832                         }
 833                 }
 834
 835                 rFile, err := fw.rsrcForkFile()
 836                 if err != nil {
 837                         return nil
 838                 }
 839
 840                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 841                         return err
 842                 }
 843
 844         case FileUpload:
 845                 s.Stats.UploadCounter += 1
 846                 s.Stats.UploadsInProgress += 1
 847                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 848
 849                 var file *os.File
 850
 851                 // A file upload has three possible cases:
 852                 // 1) Upload a new file
 853                 // 2) Resume a partially transferred file
 854                 // 3) Replace a fully uploaded file
 855                 //  We have to infer which case applies by inspecting what is already on the filesystem
 856
 857                 // 1) Check for existing file:
 858                 _, err = os.Stat(fullPath)
 859                 if err == nil {
 860                         return errors.New("existing file found at " + fullPath)
 861                 }
 862                 if errors.Is(err, fs.ErrNotExist) {
 863                         // If not found, open or create a new .incomplete file
 864                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 865                         if err != nil {
 866                                 return err
 867                         }
 868                 }
 869
 870                 f, err := newFileWrapper(s.FS, fullPath, 0)
 871                 if err != nil {
 872                         return err
 873                 }
 874
 875                 rLogger.Infow("File upload started", "dstFile", fullPath)
 876
 877                 rForkWriter := io.Discard
 878                 iForkWriter := io.Discard
 879                 if s.Config.PreserveResourceForks {
 880                         rForkWriter, err = f.rsrcForkWriter()
 881                         if err != nil {
 882                                 return err
 883                         }
 884
 885                         iForkWriter, err = f.infoForkWriter()
 886                         if err != nil {
 887                                 return err
 888                         }
 889                 }
 890
 891                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 892                         s.Logger.Error(err)
 893                 }
 894
 895                 if err := file.Close(); err != nil {
 896                         return err
 897                 }
 898
 899                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 900                         return err
 901                 }
 902
 903                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 904
 905         case FolderDownload:
 906                 s.Stats.DownloadCounter += 1
 907                 s.Stats.DownloadsInProgress += 1
 908                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 909
 910                 // Folder Download flow:
 911                 // 1. Get filePath from the transfer
 912                 // 2. Iterate over files
 913                 // 3. For each fileWrapper:
 914                 //       Send fileWrapper header to client
 915                 // The client can reply in 3 ways:
 916                 //
 917                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 918                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 919                 //
 920                 // 2. If download of a fileWrapper is to be resumed:
 921                 //              client sends:
 922                 //                      []byte{0x00, 0x02} // download folder action
 923                 //                      [2]byte // Resume data size
 924                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 925                 //
 926                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 927                 //
 928                 // When download is requested (case 2 or 3), server replies with:
 929                 //                      [4]byte - fileWrapper size
 930                 //                      []byte  - Flattened File Object
 931                 //
 932                 // After every fileWrapper download, client could request next fileWrapper with:
 933                 //                      []byte{0x00, 0x03}
 934                 //
 935                 // This notifies the server to send the next item header
 936
 937                 basePathLen := len(fullPath)
 938
 939                 rLogger.Infow("Start folder download", "path", fullPath)
 940
 941                 nextAction := make([]byte, 2)
 942                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 943                         return err
 944                 }
 945
 946                 i := 0
 947                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 948                         s.Stats.DownloadCounter += 1
 949                         i += 1
 950
 951                         if err != nil {
 952                                 return err
 953                         }
 954
 955                         // skip dot files
 956                         if strings.HasPrefix(info.Name(), ".") {
 957                                 return nil
 958                         }
 959
 960                         hlFile, err := newFileWrapper(s.FS, path, 0)
 961                         if err != nil {
 962                                 return err
 963                         }
 964
 965                         subPath := path[basePathLen+1:]
 966                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 967
 968                         if i == 1 {
 969                                 return nil
 970                         }
 971
 972                         fileHeader := NewFileHeader(subPath, info.IsDir())
 973
 974                         // Send the fileWrapper header to client
 975                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 976                                 s.Logger.Errorf("error sending file header: %v", err)
 977                                 return err
 978                         }
 979
 980                         // Read the client's Next Action request
 981                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 982                                 return err
 983                         }
 984
 985                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 986
 987                         var dataOffset int64
 988
 989                         switch nextAction[1] {
 990                         case dlFldrActionResumeFile:
 991                                 // get size of resumeData
 992                                 resumeDataByteLen := make([]byte, 2)
 993                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 994                                         return err
 995                                 }
 996
 997                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 998                                 resumeDataBytes := make([]byte, resumeDataLen)
 999                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
1000                                         return err
1001                                 }
1002
1003                                 var frd FileResumeData
1004                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1005                                         return err
1006                                 }
1007                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1008                         case dlFldrActionNextFile:
1009                                 // client asked to skip this file
1010                                 return nil
1011                         }
1012
1013                         if info.IsDir() {
1014                                 return nil
1015                         }
1016
1017                         rLogger.Infow("File download started",
1018                                 "fileName", info.Name(),
1019                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1020                         )
1021
1022                         // Send file size to client
1023                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1024                                 s.Logger.Error(err)
1025                                 return err
1026                         }
1027
1028                         // Send ffo bytes to client
1029                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1030                                 s.Logger.Error(err)
1031                                 return err
1032                         }
1033
1034                         file, err := s.FS.Open(path)
1035                         if err != nil {
1036                                 return err
1037                         }
1038
1039                         // wr := bufio.NewWriterSize(rwc, 1460)
1040                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1041                                 return err
1042                         }
1043
1044                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1045                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1046                                 if err != nil {
1047                                         return err
1048                                 }
1049
1050                                 rFile, err := hlFile.rsrcForkFile()
1051                                 if err != nil {
1052                                         return err
1053                                 }
1054
1055                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1056                                         return err
1057                                 }
1058                         }
1059
1060                         // Read the client's Next Action request.  This is always 3, I think?
1061                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1062                                 return err
1063                         }
1064
1065                         return nil
1066                 })
1067
1068                 if err != nil {
1069                         return err
1070                 }
1071
1072         case FolderUpload:
1073                 s.Stats.UploadCounter += 1
1074                 s.Stats.UploadsInProgress += 1
1075                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1076                 rLogger.Infow(
1077                         "Folder upload started",
1078                         "dstPath", fullPath,
1079                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1080                         "FolderItemCount", fileTransfer.FolderItemCount,
1081                 )
1082
1083                 // Check if the target folder exists.  If not, create it.
1084                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1085                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1086                                 return err
1087                         }
1088                 }
1089
1090                 // Begin the folder upload flow by sending the "next file action" to client
1091                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1092                         return err
1093                 }
1094
1095                 fileSize := make([]byte, 4)
1096
1097                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1098                         s.Stats.UploadCounter += 1
1099
1100                         var fu folderUpload
1101                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1102                                 return err
1103                         }
1104                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1105                                 return err
1106                         }
1107                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1108                                 return err
1109                         }
1110
1111                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1112
1113                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1114                                 return err
1115                         }
1116
1117                         rLogger.Infow(
1118                                 "Folder upload continued",
1119                                 "FormattedPath", fu.FormattedPath(),
1120                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1121                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1122                         )
1123
1124                         if fu.IsFolder == [2]byte{0, 1} {
1125                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1126                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1127                                                 return err
1128                                         }
1129                                 }
1130
1131                                 // Tell client to send next file
1132                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1133                                         return err
1134                                 }
1135                         } else {
1136                                 nextAction := dlFldrActionSendFile
1137
1138                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1139                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1140                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1141                                         return err
1142                                 }
1143                                 if err == nil {
1144                                         nextAction = dlFldrActionNextFile
1145                                 }
1146
1147                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1148                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1149                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1150                                         return err
1151                                 }
1152                                 if err == nil {
1153                                         nextAction = dlFldrActionResumeFile
1154                                 }
1155
1156                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1157                                         return err
1158                                 }
1159
1160                                 switch nextAction {
1161                                 case dlFldrActionNextFile:
1162                                         continue
1163                                 case dlFldrActionResumeFile:
1164                                         offset := make([]byte, 4)
1165                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1166
1167                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1168                                         if err != nil {
1169                                                 return err
1170                                         }
1171
1172                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1173
1174                                         b, _ := fileResumeData.BinaryMarshal()
1175
1176                                         bs := make([]byte, 2)
1177                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1178
1179                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1180                                                 return err
1181                                         }
1182
1183                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1184                                                 return err
1185                                         }
1186
1187                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1188                                                 s.Logger.Error(err)
1189                                         }
1190
1191                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1192                                         if err != nil {
1193                                                 return err
1194                                         }
1195
1196                                 case dlFldrActionSendFile:
1197                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1198                                                 return err
1199                                         }
1200
1201                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1202
1203                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1204                                         if err != nil {
1205                                                 return err
1206                                         }
1207
1208                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1209
1210                                         incWriter, err := hlFile.incFileWriter()
1211                                         if err != nil {
1212                                                 return err
1213                                         }
1214
1215                                         rForkWriter := io.Discard
1216                                         iForkWriter := io.Discard
1217                                         if s.Config.PreserveResourceForks {
1218                                                 iForkWriter, err = hlFile.infoForkWriter()
1219                                                 if err != nil {
1220                                                         return err
1221                                                 }
1222
1223                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1224                                                 if err != nil {
1225                                                         return err
1226                                                 }
1227                                         }
1228                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1229                                                 return err
1230                                         }
1231
1232                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1233                                                 return err
1234                                         }
1235                                 }
1236
1237                                 // Tell client to send next fileWrapper
1238                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1239                                         return err
1240                                 }
1241                         }
1242                 }
1243                 rLogger.Infof("Folder upload complete")
1244         }
1245
1246         return nil
1247 }