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         "golang.org/x/text/encoding/charmap"
  13         "gopkg.in/yaml.v3"
  14         "io"
  15         "io/fs"
  16         "math/big"
  17         "math/rand"
  18         "net"
  19         "os"
  20         "path"
  21         "path/filepath"
  22         "strings"
  23         "sync"
  24         "time"
  25 )
  26
  27 type contextKey string
  28
  29 var contextKeyReq = contextKey("req")
  30
  31 type requestCtx struct {
  32         remoteAddr string
  33 }
  34
  35 // Converts bytes from Mac Roman encoding to UTF-8
  36 var txtDecoder = charmap.Macintosh.NewDecoder()
  37
  38 // Converts bytes from UTF-8 to Mac Roman encoding
  39 var txtEncoder = charmap.Macintosh.NewEncoder()
  40
  41 type Server struct {
  42         NetInterface  string
  43         Port          int
  44         Accounts      map[string]*Account
  45         Agreement     []byte
  46         Clients       map[uint16]*ClientConn
  47         fileTransfers map[[4]byte]*FileTransfer
  48
  49         Config    *Config
  50         ConfigDir string
  51         Logger    *zap.SugaredLogger
  52         banner    []byte
  53
  54         PrivateChatsMu sync.Mutex
  55         PrivateChats   map[uint32]*PrivateChat
  56
  57         NextGuestID   *uint16
  58         TrackerPassID [4]byte
  59
  60         StatsMu sync.Mutex
  61         Stats   *Stats
  62
  63         FS FileStore // Storage backend to use for File storage
  64
  65         outbox chan Transaction
  66         mux    sync.Mutex
  67
  68         threadedNewsMux sync.Mutex
  69         ThreadedNews    *ThreadedNews
  70
  71         flatNewsMux sync.Mutex
  72         FlatNews    []byte
  73
  74         banListMU sync.Mutex
  75         banList   map[string]*time.Time
  76 }
  77
  78 func (s *Server) CurrentStats() Stats {
  79         s.StatsMu.Lock()
  80         defer s.StatsMu.Unlock()
  81
  82         stats := s.Stats
  83         stats.CurrentlyConnected = len(s.Clients)
  84
  85         return *stats
  86 }
  87
  88 type PrivateChat struct {
  89         Subject    string
  90         ClientConn map[uint16]*ClientConn
  91 }
  92
  93 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  94         s.Logger.Infow("Hotline server started",
  95                 "version", VERSION,
  96                 "API port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port),
  97                 "Transfer port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1),
  98         )
  99
 100         var wg sync.WaitGroup
 101
 102         wg.Add(1)
 103         go func() {
 104                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
 105                 if err != nil {
 106                         s.Logger.Fatal(err)
 107                 }
 108
 109                 s.Logger.Fatal(s.Serve(ctx, ln))
 110         }()
 111
 112         wg.Add(1)
 113         go func() {
 114                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
 115                 if err != nil {
 116                         s.Logger.Fatal(err)
 117                 }
 118
 119                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 120         }()
 121
 122         wg.Wait()
 123
 124         return nil
 125 }
 126
 127 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 128         for {
 129                 conn, err := ln.Accept()
 130                 if err != nil {
 131                         return err
 132                 }
 133
 134                 go func() {
 135                         defer func() { _ = conn.Close() }()
 136
 137                         err = s.handleFileTransfer(
 138                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 139                                         remoteAddr: conn.RemoteAddr().String(),
 140                                 }),
 141                                 conn,
 142                         )
 143
 144                         if err != nil {
 145                                 s.Logger.Errorw("file transfer error", "reason", err)
 146                         }
 147                 }()
 148         }
 149 }
 150
 151 func (s *Server) sendTransaction(t Transaction) error {
 152         clientID, err := byteToInt(*t.clientID)
 153         if err != nil {
 154                 return err
 155         }
 156
 157         s.mux.Lock()
 158         client := s.Clients[uint16(clientID)]
 159         s.mux.Unlock()
 160         if client == nil {
 161                 return fmt.Errorf("invalid client id %v", *t.clientID)
 162         }
 163
 164         b, err := t.MarshalBinary()
 165         if err != nil {
 166                 return err
 167         }
 168
 169         _, err = client.Connection.Write(b)
 170         if err != nil {
 171                 return err
 172         }
 173
 174         return nil
 175 }
 176
 177 func (s *Server) processOutbox() {
 178         for {
 179                 t := <-s.outbox
 180                 go func() {
 181                         if err := s.sendTransaction(t); err != nil {
 182                                 s.Logger.Errorw("error sending transaction", "err", err)
 183                         }
 184                 }()
 185         }
 186 }
 187
 188 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 189         go s.processOutbox()
 190
 191         for {
 192                 conn, err := ln.Accept()
 193                 if err != nil {
 194                         s.Logger.Errorw("error accepting connection", "err", err)
 195                 }
 196                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 197                         remoteAddr: conn.RemoteAddr().String(),
 198                 })
 199
 200                 go func() {
 201                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 202
 203                         defer conn.Close()
 204                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 205                                 if err == io.EOF {
 206                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 207                                 } else {
 208                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 209                                 }
 210                         }
 211                 }()
 212         }
 213 }
 214
 215 const (
 216         agreementFile = "Agreement.txt"
 217 )
 218
 219 // NewServer constructs a new Server from a config dir
 220 func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredLogger, fs FileStore) (*Server, error) {
 221         server := Server{
 222                 NetInterface:  netInterface,
 223                 Port:          netPort,
 224                 Accounts:      make(map[string]*Account),
 225                 Config:        new(Config),
 226                 Clients:       make(map[uint16]*ClientConn),
 227                 fileTransfers: make(map[[4]byte]*FileTransfer),
 228                 PrivateChats:  make(map[uint32]*PrivateChat),
 229                 ConfigDir:     configDir,
 230                 Logger:        logger,
 231                 NextGuestID:   new(uint16),
 232                 outbox:        make(chan Transaction),
 233                 Stats:         &Stats{Since: time.Now()},
 234                 ThreadedNews:  &ThreadedNews{},
 235                 FS:            fs,
 236                 banList:       make(map[string]*time.Time),
 237         }
 238
 239         var err error
 240
 241         // generate a new random passID for tracker registration
 242         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 243                 return nil, err
 244         }
 245
 246         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 247         if err != nil {
 248                 return nil, err
 249         }
 250
 251         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 252                 return nil, err
 253         }
 254
 255         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 256         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 257
 258         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 259                 return nil, err
 260         }
 261
 262         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 263                 return nil, err
 264         }
 265
 266         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 267                 return nil, err
 268         }
 269
 270         // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
 271         if !filepath.IsAbs(server.Config.FileRoot) {
 272                 server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
 273         }
 274
 275         server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
 276         if err != nil {
 277                 return nil, fmt.Errorf("error opening banner: %w", err)
 278         }
 279
 280         *server.NextGuestID = 1
 281
 282         if server.Config.EnableTrackerRegistration {
 283                 server.Logger.Infow(
 284                         "Tracker registration enabled",
 285                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 286                         "trackers", server.Config.Trackers,
 287                 )
 288
 289                 go func() {
 290                         for {
 291                                 tr := &TrackerRegistration{
 292                                         UserCount:   server.userCount(),
 293                                         PassID:      server.TrackerPassID,
 294                                         Name:        server.Config.Name,
 295                                         Description: server.Config.Description,
 296                                 }
 297                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 298                                 for _, t := range server.Config.Trackers {
 299                                         if err := register(t, tr); err != nil {
 300                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 301                                         }
 302                                         server.Logger.Debugw("Sent Tracker registration", "addr", t)
 303                                 }
 304
 305                                 time.Sleep(trackerUpdateFrequency * time.Second)
 306                         }
 307                 }()
 308         }
 309
 310         // Start Client Keepalive go routine
 311         go server.keepaliveHandler()
 312
 313         return &server, nil
 314 }
 315
 316 func (s *Server) userCount() int {
 317         s.mux.Lock()
 318         defer s.mux.Unlock()
 319
 320         return len(s.Clients)
 321 }
 322
 323 func (s *Server) keepaliveHandler() {
 324         for {
 325                 time.Sleep(idleCheckInterval * time.Second)
 326                 s.mux.Lock()
 327
 328                 for _, c := range s.Clients {
 329                         c.IdleTime += idleCheckInterval
 330                         if c.IdleTime > userIdleSeconds && !c.Idle {
 331                                 c.Idle = true
 332
 333                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 334                                 flagBitmap.SetBit(flagBitmap, UserFlagAway, 1)
 335                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 336
 337                                 c.sendAll(
 338                                         TranNotifyChangeUser,
 339                                         NewField(FieldUserID, *c.ID),
 340                                         NewField(FieldUserFlags, c.Flags),
 341                                         NewField(FieldUserName, c.UserName),
 342                                         NewField(FieldUserIconID, c.Icon),
 343                                 )
 344                         }
 345                 }
 346                 s.mux.Unlock()
 347         }
 348 }
 349
 350 func (s *Server) writeBanList() error {
 351         s.banListMU.Lock()
 352         defer s.banListMU.Unlock()
 353
 354         out, err := yaml.Marshal(s.banList)
 355         if err != nil {
 356                 return err
 357         }
 358         err = os.WriteFile(
 359                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 360                 out,
 361                 0666,
 362         )
 363         return err
 364 }
 365
 366 func (s *Server) writeThreadedNews() error {
 367         s.threadedNewsMux.Lock()
 368         defer s.threadedNewsMux.Unlock()
 369
 370         out, err := yaml.Marshal(s.ThreadedNews)
 371         if err != nil {
 372                 return err
 373         }
 374         err = s.FS.WriteFile(
 375                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 376                 out,
 377                 0666,
 378         )
 379         return err
 380 }
 381
 382 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 383         s.mux.Lock()
 384         defer s.mux.Unlock()
 385
 386         clientConn := &ClientConn{
 387                 ID:         &[]byte{0, 0},
 388                 Icon:       []byte{0, 0},
 389                 Flags:      []byte{0, 0},
 390                 UserName:   []byte{},
 391                 Connection: conn,
 392                 Server:     s,
 393                 Version:    []byte{},
 394                 AutoReply:  []byte{},
 395                 RemoteAddr: remoteAddr,
 396                 transfers: map[int]map[[4]byte]*FileTransfer{
 397                         FileDownload:   {},
 398                         FileUpload:     {},
 399                         FolderDownload: {},
 400                         FolderUpload:   {},
 401                         bannerDownload: {},
 402                 },
 403         }
 404
 405         *s.NextGuestID++
 406         ID := *s.NextGuestID
 407
 408         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 409         s.Clients[ID] = clientConn
 410
 411         return clientConn
 412 }
 413
 414 // NewUser creates a new user account entry in the server map and config file
 415 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 416         s.mux.Lock()
 417         defer s.mux.Unlock()
 418
 419         account := Account{
 420                 Login:    login,
 421                 Name:     name,
 422                 Password: hashAndSalt([]byte(password)),
 423                 Access:   access,
 424         }
 425         out, err := yaml.Marshal(&account)
 426         if err != nil {
 427                 return err
 428         }
 429
 430         // Create account file, returning an error if one already exists.
 431         file, err := os.OpenFile(
 432                 filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
 433                 os.O_CREATE|os.O_EXCL|os.O_WRONLY,
 434                 0644,
 435         )
 436         if err != nil {
 437                 return err
 438         }
 439         defer file.Close()
 440
 441         _, err = file.Write(out)
 442         if err != nil {
 443                 return fmt.Errorf("error writing account file: %w", err)
 444         }
 445
 446         s.Accounts[login] = &account
 447
 448         return nil
 449 }
 450
 451 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 452         s.mux.Lock()
 453         defer s.mux.Unlock()
 454
 455         // update renames the user login
 456         if login != newLogin {
 457                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"), filepath.Join(s.ConfigDir, "Users", path.Join("/", newLogin)+".yaml"))
 458                 if err != nil {
 459                         return fmt.Errorf("unable to rename account: %w", err)
 460                 }
 461                 s.Accounts[newLogin] = s.Accounts[login]
 462                 s.Accounts[newLogin].Login = newLogin
 463                 delete(s.Accounts, login)
 464         }
 465
 466         account := s.Accounts[newLogin]
 467         account.Access = access
 468         account.Name = name
 469         account.Password = password
 470
 471         out, err := yaml.Marshal(&account)
 472         if err != nil {
 473                 return err
 474         }
 475
 476         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 477                 return err
 478         }
 479
 480         return nil
 481 }
 482
 483 // DeleteUser deletes the user account
 484 func (s *Server) DeleteUser(login string) error {
 485         s.mux.Lock()
 486         defer s.mux.Unlock()
 487
 488         err := s.FS.Remove(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"))
 489         if err != nil {
 490                 return err
 491         }
 492
 493         delete(s.Accounts, login)
 494
 495         return nil
 496 }
 497
 498 func (s *Server) connectedUsers() []Field {
 499         s.mux.Lock()
 500         defer s.mux.Unlock()
 501
 502         var connectedUsers []Field
 503         for _, c := range sortedClients(s.Clients) {
 504                 b, err := io.ReadAll(&User{
 505                         ID:    *c.ID,
 506                         Icon:  c.Icon,
 507                         Flags: c.Flags,
 508                         Name:  string(c.UserName),
 509                 })
 510                 if err != nil {
 511                         return nil
 512                 }
 513                 connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, b))
 514         }
 515         return connectedUsers
 516 }
 517
 518 func (s *Server) loadBanList(path string) error {
 519         fh, err := os.Open(path)
 520         if err != nil {
 521                 return err
 522         }
 523         decoder := yaml.NewDecoder(fh)
 524
 525         return decoder.Decode(s.banList)
 526 }
 527
 528 // loadThreadedNews loads the threaded news data from disk
 529 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 530         fh, err := os.Open(threadedNewsPath)
 531         if err != nil {
 532                 return err
 533         }
 534         decoder := yaml.NewDecoder(fh)
 535
 536         return decoder.Decode(s.ThreadedNews)
 537 }
 538
 539 // loadAccounts loads account data from disk
 540 func (s *Server) loadAccounts(userDir string) error {
 541         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 542         if err != nil {
 543                 return err
 544         }
 545
 546         if len(matches) == 0 {
 547                 return errors.New("no user accounts found in " + userDir)
 548         }
 549
 550         for _, file := range matches {
 551                 fh, err := s.FS.Open(file)
 552                 if err != nil {
 553                         return err
 554                 }
 555
 556                 account := Account{}
 557                 decoder := yaml.NewDecoder(fh)
 558                 if err = decoder.Decode(&account); err != nil {
 559                         return fmt.Errorf("error loading account %s: %w", file, err)
 560                 }
 561
 562                 s.Accounts[account.Login] = &account
 563         }
 564         return nil
 565 }
 566
 567 func (s *Server) loadConfig(path string) error {
 568         fh, err := s.FS.Open(path)
 569         if err != nil {
 570                 return err
 571         }
 572
 573         decoder := yaml.NewDecoder(fh)
 574         err = decoder.Decode(s.Config)
 575         if err != nil {
 576                 return err
 577         }
 578
 579         validate := validator.New()
 580         err = validate.Struct(s.Config)
 581         if err != nil {
 582                 return err
 583         }
 584         return nil
 585 }
 586
 587 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 588 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 589         defer dontPanic(s.Logger)
 590
 591         if err := Handshake(rwc); err != nil {
 592                 return err
 593         }
 594
 595         // Create a new scanner for parsing incoming bytes into transaction tokens
 596         scanner := bufio.NewScanner(rwc)
 597         scanner.Split(transactionScanner)
 598
 599         scanner.Scan()
 600
 601         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 602         // scanner re-uses the buffer for subsequent scans.
 603         buf := make([]byte, len(scanner.Bytes()))
 604         copy(buf, scanner.Bytes())
 605
 606         var clientLogin Transaction
 607         if _, err := clientLogin.Write(buf); err != nil {
 608                 return err
 609         }
 610
 611         // check if remoteAddr is present in the ban list
 612         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 613                 // permaban
 614                 if banUntil == nil {
 615                         t := NewTransaction(
 616                                 TranServerMsg,
 617                                 &[]byte{0, 0},
 618                                 NewField(FieldData, []byte("You are permanently banned on this server")),
 619                                 NewField(FieldChatOptions, []byte{0, 0}),
 620                         )
 621
 622                         b, err := t.MarshalBinary()
 623                         if err != nil {
 624                                 return err
 625                         }
 626
 627                         _, err = rwc.Write(b)
 628                         if err != nil {
 629                                 return err
 630                         }
 631
 632                         time.Sleep(1 * time.Second)
 633                         return nil
 634                 }
 635
 636                 // temporary ban
 637                 if time.Now().Before(*banUntil) {
 638                         t := NewTransaction(
 639                                 TranServerMsg,
 640                                 &[]byte{0, 0},
 641                                 NewField(FieldData, []byte("You are temporarily banned on this server")),
 642                                 NewField(FieldChatOptions, []byte{0, 0}),
 643                         )
 644                         b, err := t.MarshalBinary()
 645                         if err != nil {
 646                                 return err
 647                         }
 648
 649                         _, err = rwc.Write(b)
 650                         if err != nil {
 651                                 return err
 652                         }
 653
 654                         time.Sleep(1 * time.Second)
 655                         return nil
 656                 }
 657         }
 658
 659         c := s.NewClientConn(rwc, remoteAddr)
 660         defer c.Disconnect()
 661
 662         encodedLogin := clientLogin.GetField(FieldUserLogin).Data
 663         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 664         c.Version = clientLogin.GetField(FieldVersion).Data
 665
 666         var login string
 667         for _, char := range encodedLogin {
 668                 login += string(rune(255 - uint(char)))
 669         }
 670         if login == "" {
 671                 login = GuestAccount
 672         }
 673
 674         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 675
 676         // If authentication fails, send error reply and close connection
 677         if !c.Authenticate(login, encodedPassword) {
 678                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 679                 b, err := t.MarshalBinary()
 680                 if err != nil {
 681                         return err
 682                 }
 683                 if _, err := rwc.Write(b); err != nil {
 684                         return err
 685                 }
 686
 687                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 688
 689                 return nil
 690         }
 691
 692         if clientLogin.GetField(FieldUserIconID).Data != nil {
 693                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 694         }
 695
 696         c.Account = c.Server.Accounts[login]
 697
 698         if clientLogin.GetField(FieldUserName).Data != nil {
 699                 if c.Authorize(accessAnyName) {
 700                         c.UserName = clientLogin.GetField(FieldUserName).Data
 701                 } else {
 702                         c.UserName = []byte(c.Account.Name)
 703                 }
 704         }
 705
 706         if c.Authorize(accessDisconUser) {
 707                 c.Flags = []byte{0, 2}
 708         }
 709
 710         s.outbox <- c.NewReply(&clientLogin,
 711                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 712                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 713                 NewField(FieldServerName, []byte(s.Config.Name)),
 714         )
 715
 716         // Send user access privs so client UI knows how to behave
 717         c.Server.outbox <- *NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 718
 719         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 720         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 721         // TranShowAgreement but with the NoServerAgreement field set to 1.
 722         if c.Authorize(accessNoAgreement) {
 723                 // If client version is nil, then the client uses the 1.2.3 login behavior
 724                 if c.Version != nil {
 725                         c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 726                 }
 727         } else {
 728                 c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
 729         }
 730
 731         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 732         // flow and not the 1.5+ flow.
 733         if len(c.UserName) != 0 {
 734                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 735                 // part of TranAgreed
 736                 c.logger = c.logger.With("name", string(c.UserName))
 737
 738                 c.logger.Infow("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
 739
 740                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 741                 // information yet, so we do it in TranAgreed instead
 742                 for _, t := range c.notifyOthers(
 743                         *NewTransaction(
 744                                 TranNotifyChangeUser, nil,
 745                                 NewField(FieldUserName, c.UserName),
 746                                 NewField(FieldUserID, *c.ID),
 747                                 NewField(FieldUserIconID, c.Icon),
 748                                 NewField(FieldUserFlags, c.Flags),
 749                         ),
 750                 ) {
 751                         c.Server.outbox <- t
 752                 }
 753         }
 754
 755         c.Server.Stats.ConnectionCounter += 1
 756         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 757                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 758         }
 759
 760         // Scan for new transactions and handle them as they come in.
 761         for scanner.Scan() {
 762                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 763                 // scanner re-uses the buffer for subsequent scans.
 764                 buf := make([]byte, len(scanner.Bytes()))
 765                 copy(buf, scanner.Bytes())
 766
 767                 var t Transaction
 768                 if _, err := t.Write(buf); err != nil {
 769                         return err
 770                 }
 771
 772                 if err := c.handleTransaction(t); err != nil {
 773                         c.logger.Errorw("Error handling transaction", "err", err)
 774                 }
 775         }
 776         return nil
 777 }
 778
 779 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 780         s.PrivateChatsMu.Lock()
 781         defer s.PrivateChatsMu.Unlock()
 782
 783         randID := make([]byte, 4)
 784         rand.Read(randID)
 785         data := binary.BigEndian.Uint32(randID)
 786
 787         s.PrivateChats[data] = &PrivateChat{
 788                 ClientConn: make(map[uint16]*ClientConn),
 789         }
 790         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 791
 792         return randID
 793 }
 794
 795 const dlFldrActionSendFile = 1
 796 const dlFldrActionResumeFile = 2
 797 const dlFldrActionNextFile = 3
 798
 799 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 800 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 801         defer dontPanic(s.Logger)
 802
 803         txBuf := make([]byte, 16)
 804         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 805                 return err
 806         }
 807
 808         var t transfer
 809         if _, err := t.Write(txBuf); err != nil {
 810                 return err
 811         }
 812
 813         defer func() {
 814                 s.mux.Lock()
 815                 delete(s.fileTransfers, t.ReferenceNumber)
 816                 s.mux.Unlock()
 817
 818                 // Wait a few seconds before closing the connection: this is a workaround for problems
 819                 // observed with Windows clients where the client must initiate close of the TCP connection before
 820                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 821                 time.Sleep(3 * time.Second)
 822         }()
 823
 824         s.mux.Lock()
 825         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 826         s.mux.Unlock()
 827         if !ok {
 828                 return errors.New("invalid transaction ID")
 829         }
 830
 831         defer func() {
 832                 fileTransfer.ClientConn.transfersMU.Lock()
 833                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 834                 fileTransfer.ClientConn.transfersMU.Unlock()
 835         }()
 836
 837         rLogger := s.Logger.With(
 838                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 839                 "login", fileTransfer.ClientConn.Account.Login,
 840                 "name", string(fileTransfer.ClientConn.UserName),
 841         )
 842
 843         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 844         if err != nil {
 845                 return err
 846         }
 847
 848         switch fileTransfer.Type {
 849         case bannerDownload:
 850                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
 851                         return fmt.Errorf("error sending banner: %w", err)
 852                 }
 853         case FileDownload:
 854                 s.Stats.DownloadCounter += 1
 855                 s.Stats.DownloadsInProgress += 1
 856                 defer func() {
 857                         s.Stats.DownloadsInProgress -= 1
 858                 }()
 859
 860                 var dataOffset int64
 861                 if fileTransfer.fileResumeData != nil {
 862                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 863                 }
 864
 865                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 866                 if err != nil {
 867                         return err
 868                 }
 869
 870                 rLogger.Infow("File download started", "filePath", fullPath)
 871
 872                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 873                 if fileTransfer.options == nil {
 874                         _, err = io.Copy(rwc, fw.ffo)
 875                         if err != nil {
 876                                 return err
 877                         }
 878                 }
 879
 880                 file, err := fw.dataForkReader()
 881                 if err != nil {
 882                         return err
 883                 }
 884
 885                 br := bufio.NewReader(file)
 886                 if _, err := br.Discard(int(dataOffset)); err != nil {
 887                         return err
 888                 }
 889
 890                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 891                         return err
 892                 }
 893
 894                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 895                 if fileTransfer.fileResumeData == nil {
 896                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 897                         if err != nil {
 898                                 return err
 899                         }
 900                 }
 901
 902                 rFile, err := fw.rsrcForkFile()
 903                 if err != nil {
 904                         return nil
 905                 }
 906
 907                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 908                         return err
 909                 }
 910
 911         case FileUpload:
 912                 s.Stats.UploadCounter += 1
 913                 s.Stats.UploadsInProgress += 1
 914                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 915
 916                 var file *os.File
 917
 918                 // A file upload has three possible cases:
 919                 // 1) Upload a new file
 920                 // 2) Resume a partially transferred file
 921                 // 3) Replace a fully uploaded file
 922                 //  We have to infer which case applies by inspecting what is already on the filesystem
 923
 924                 // 1) Check for existing file:
 925                 _, err = os.Stat(fullPath)
 926                 if err == nil {
 927                         return errors.New("existing file found at " + fullPath)
 928                 }
 929                 if errors.Is(err, fs.ErrNotExist) {
 930                         // If not found, open or create a new .incomplete file
 931                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 932                         if err != nil {
 933                                 return err
 934                         }
 935                 }
 936
 937                 f, err := newFileWrapper(s.FS, fullPath, 0)
 938                 if err != nil {
 939                         return err
 940                 }
 941
 942                 rLogger.Infow("File upload started", "dstFile", fullPath)
 943
 944                 rForkWriter := io.Discard
 945                 iForkWriter := io.Discard
 946                 if s.Config.PreserveResourceForks {
 947                         rForkWriter, err = f.rsrcForkWriter()
 948                         if err != nil {
 949                                 return err
 950                         }
 951
 952                         iForkWriter, err = f.infoForkWriter()
 953                         if err != nil {
 954                                 return err
 955                         }
 956                 }
 957
 958                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 959                         s.Logger.Error(err)
 960                 }
 961
 962                 if err := file.Close(); err != nil {
 963                         return err
 964                 }
 965
 966                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 967                         return err
 968                 }
 969
 970                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 971
 972         case FolderDownload:
 973                 s.Stats.DownloadCounter += 1
 974                 s.Stats.DownloadsInProgress += 1
 975                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 976
 977                 // Folder Download flow:
 978                 // 1. Get filePath from the transfer
 979                 // 2. Iterate over files
 980                 // 3. For each fileWrapper:
 981                 //       Send fileWrapper header to client
 982                 // The client can reply in 3 ways:
 983                 //
 984                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 985                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 986                 //
 987                 // 2. If download of a fileWrapper is to be resumed:
 988                 //              client sends:
 989                 //                      []byte{0x00, 0x02} // download folder action
 990                 //                      [2]byte // Resume data size
 991                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 992                 //
 993                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 994                 //
 995                 // When download is requested (case 2 or 3), server replies with:
 996                 //                      [4]byte - fileWrapper size
 997                 //                      []byte  - Flattened File Object
 998                 //
 999                 // After every fileWrapper download, client could request next fileWrapper with:
1000                 //                      []byte{0x00, 0x03}
1001                 //
1002                 // This notifies the server to send the next item header
1003
1004                 basePathLen := len(fullPath)
1005
1006                 rLogger.Infow("Start folder download", "path", fullPath)
1007
1008                 nextAction := make([]byte, 2)
1009                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
1010                         return err
1011                 }
1012
1013                 i := 0
1014                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
1015                         s.Stats.DownloadCounter += 1
1016                         i += 1
1017
1018                         if err != nil {
1019                                 return err
1020                         }
1021
1022                         // skip dot files
1023                         if strings.HasPrefix(info.Name(), ".") {
1024                                 return nil
1025                         }
1026
1027                         hlFile, err := newFileWrapper(s.FS, path, 0)
1028                         if err != nil {
1029                                 return err
1030                         }
1031
1032                         subPath := path[basePathLen+1:]
1033                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
1034
1035                         if i == 1 {
1036                                 return nil
1037                         }
1038
1039                         fileHeader := NewFileHeader(subPath, info.IsDir())
1040                         if _, err := io.Copy(rwc, &fileHeader); err != nil {
1041                                 return fmt.Errorf("error sending file header: %w", err)
1042                         }
1043
1044                         // Read the client's Next Action request
1045                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1046                                 return err
1047                         }
1048
1049                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
1050
1051                         var dataOffset int64
1052
1053                         switch nextAction[1] {
1054                         case dlFldrActionResumeFile:
1055                                 // get size of resumeData
1056                                 resumeDataByteLen := make([]byte, 2)
1057                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
1058                                         return err
1059                                 }
1060
1061                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
1062                                 resumeDataBytes := make([]byte, resumeDataLen)
1063                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
1064                                         return err
1065                                 }
1066
1067                                 var frd FileResumeData
1068                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1069                                         return err
1070                                 }
1071                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1072                         case dlFldrActionNextFile:
1073                                 // client asked to skip this file
1074                                 return nil
1075                         }
1076
1077                         if info.IsDir() {
1078                                 return nil
1079                         }
1080
1081                         rLogger.Infow("File download started",
1082                                 "fileName", info.Name(),
1083                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1084                         )
1085
1086                         // Send file size to client
1087                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1088                                 s.Logger.Error(err)
1089                                 return err
1090                         }
1091
1092                         // Send ffo bytes to client
1093                         _, err = io.Copy(rwc, hlFile.ffo)
1094                         if err != nil {
1095                                 return err
1096                         }
1097
1098                         file, err := s.FS.Open(path)
1099                         if err != nil {
1100                                 return err
1101                         }
1102
1103                         // wr := bufio.NewWriterSize(rwc, 1460)
1104                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1105                                 return err
1106                         }
1107
1108                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1109                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1110                                 if err != nil {
1111                                         return err
1112                                 }
1113
1114                                 rFile, err := hlFile.rsrcForkFile()
1115                                 if err != nil {
1116                                         return err
1117                                 }
1118
1119                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1120                                         return err
1121                                 }
1122                         }
1123
1124                         // Read the client's Next Action request.  This is always 3, I think?
1125                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1126                                 return err
1127                         }
1128
1129                         return nil
1130                 })
1131
1132                 if err != nil {
1133                         return err
1134                 }
1135
1136         case FolderUpload:
1137                 s.Stats.UploadCounter += 1
1138                 s.Stats.UploadsInProgress += 1
1139                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1140                 rLogger.Infow(
1141                         "Folder upload started",
1142                         "dstPath", fullPath,
1143                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1144                         "FolderItemCount", fileTransfer.FolderItemCount,
1145                 )
1146
1147                 // Check if the target folder exists.  If not, create it.
1148                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1149                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1150                                 return err
1151                         }
1152                 }
1153
1154                 // Begin the folder upload flow by sending the "next file action" to client
1155                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1156                         return err
1157                 }
1158
1159                 fileSize := make([]byte, 4)
1160
1161                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1162                         s.Stats.UploadCounter += 1
1163
1164                         var fu folderUpload
1165                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1166                                 return err
1167                         }
1168                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1169                                 return err
1170                         }
1171                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1172                                 return err
1173                         }
1174
1175                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1176
1177                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1178                                 return err
1179                         }
1180
1181                         rLogger.Infow(
1182                                 "Folder upload continued",
1183                                 "FormattedPath", fu.FormattedPath(),
1184                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1185                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1186                         )
1187
1188                         if fu.IsFolder == [2]byte{0, 1} {
1189                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1190                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1191                                                 return err
1192                                         }
1193                                 }
1194
1195                                 // Tell client to send next file
1196                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1197                                         return err
1198                                 }
1199                         } else {
1200                                 nextAction := dlFldrActionSendFile
1201
1202                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1203                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1204                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1205                                         return err
1206                                 }
1207                                 if err == nil {
1208                                         nextAction = dlFldrActionNextFile
1209                                 }
1210
1211                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1212                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1213                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1214                                         return err
1215                                 }
1216                                 if err == nil {
1217                                         nextAction = dlFldrActionResumeFile
1218                                 }
1219
1220                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1221                                         return err
1222                                 }
1223
1224                                 switch nextAction {
1225                                 case dlFldrActionNextFile:
1226                                         continue
1227                                 case dlFldrActionResumeFile:
1228                                         offset := make([]byte, 4)
1229                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1230
1231                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1232                                         if err != nil {
1233                                                 return err
1234                                         }
1235
1236                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1237
1238                                         b, _ := fileResumeData.BinaryMarshal()
1239
1240                                         bs := make([]byte, 2)
1241                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1242
1243                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1244                                                 return err
1245                                         }
1246
1247                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1248                                                 return err
1249                                         }
1250
1251                                         if err := receiveFile(rwc, file, io.Discard, io.Discard, fileTransfer.bytesSentCounter); err != nil {
1252                                                 s.Logger.Error(err)
1253                                         }
1254
1255                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1256                                         if err != nil {
1257                                                 return err
1258                                         }
1259
1260                                 case dlFldrActionSendFile:
1261                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1262                                                 return err
1263                                         }
1264
1265                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1266
1267                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1268                                         if err != nil {
1269                                                 return err
1270                                         }
1271
1272                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1273
1274                                         incWriter, err := hlFile.incFileWriter()
1275                                         if err != nil {
1276                                                 return err
1277                                         }
1278
1279                                         rForkWriter := io.Discard
1280                                         iForkWriter := io.Discard
1281                                         if s.Config.PreserveResourceForks {
1282                                                 iForkWriter, err = hlFile.infoForkWriter()
1283                                                 if err != nil {
1284                                                         return err
1285                                                 }
1286
1287                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1288                                                 if err != nil {
1289                                                         return err
1290                                                 }
1291                                         }
1292                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1293                                                 return err
1294                                         }
1295
1296                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1297                                                 return err
1298                                         }
1299                                 }
1300
1301                                 // Tell client to send next fileWrapper
1302                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1303                                         return err
1304                                 }
1305                         }
1306                 }
1307                 rLogger.Infof("Folder upload complete")
1308         }
1309
1310         return nil
1311 }