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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "bytes"
   6         "context"
   7         "crypto/rand"
   8         "encoding/binary"
   9         "errors"
  10         "fmt"
  11         "github.com/go-playground/validator/v10"
  12         "golang.org/x/text/encoding/charmap"
  13         "gopkg.in/yaml.v3"
  14         "io"
  15         "log"
  16         "log/slog"
  17         "net"
  18         "os"
  19         "path"
  20         "path/filepath"
  21         "strings"
  22         "sync"
  23         "sync/atomic"
  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
  47         Clients       map[[2]byte]*ClientConn
  48         fileTransfers map[[4]byte]*FileTransfer
  49
  50         Config    *Config
  51         ConfigDir string
  52         Logger    *slog.Logger
  53         banner    []byte
  54
  55         PrivateChatsMu sync.Mutex
  56         PrivateChats   map[[4]byte]*PrivateChat
  57
  58         nextClientID  atomic.Uint32
  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[[2]byte]*ClientConn
  92 }
  93
  94 func (s *Server) ListenAndServe(ctx context.Context) error {
  95         var wg sync.WaitGroup
  96
  97         wg.Add(1)
  98         go func() {
  99                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
 100                 if err != nil {
 101                         log.Fatal(err)
 102                 }
 103
 104                 log.Fatal(s.Serve(ctx, ln))
 105         }()
 106
 107         wg.Add(1)
 108         go func() {
 109                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
 110                 if err != nil {
 111                         log.Fatal(err)
 112                 }
 113
 114                 log.Fatal(s.ServeFileTransfers(ctx, ln))
 115         }()
 116
 117         wg.Wait()
 118
 119         return nil
 120 }
 121
 122 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 123         for {
 124                 conn, err := ln.Accept()
 125                 if err != nil {
 126                         return err
 127                 }
 128
 129                 go func() {
 130                         defer func() { _ = conn.Close() }()
 131
 132                         err = s.handleFileTransfer(
 133                                 context.WithValue(ctx, contextKeyReq, requestCtx{remoteAddr: conn.RemoteAddr().String()}),
 134                                 conn,
 135                         )
 136
 137                         if err != nil {
 138                                 s.Logger.Error("file transfer error", "reason", err)
 139                         }
 140                 }()
 141         }
 142 }
 143
 144 func (s *Server) sendTransaction(t Transaction) error {
 145         s.mux.Lock()
 146         client, ok := s.Clients[t.clientID]
 147         s.mux.Unlock()
 148
 149         if !ok || client == nil {
 150                 return nil
 151         }
 152
 153         _, err := io.Copy(client.Connection, &t)
 154         if err != nil {
 155                 return fmt.Errorf("failed to send transaction to client %v: %v", t.clientID, err)
 156         }
 157
 158         return nil
 159 }
 160
 161 func (s *Server) processOutbox() {
 162         for {
 163                 t := <-s.outbox
 164                 go func() {
 165                         if err := s.sendTransaction(t); err != nil {
 166                                 s.Logger.Error("error sending transaction", "err", err)
 167                         }
 168                 }()
 169         }
 170 }
 171
 172 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 173         go s.processOutbox()
 174
 175         for {
 176                 conn, err := ln.Accept()
 177                 if err != nil {
 178                         s.Logger.Error("error accepting connection", "err", err)
 179                 }
 180                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 181                         remoteAddr: conn.RemoteAddr().String(),
 182                 })
 183
 184                 go func() {
 185                         s.Logger.Info("Connection established", "RemoteAddr", conn.RemoteAddr())
 186
 187                         defer conn.Close()
 188                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 189                                 if err == io.EOF {
 190                                         s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 191                                 } else {
 192                                         s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 193                                 }
 194                         }
 195                 }()
 196         }
 197 }
 198
 199 const (
 200         agreementFile = "Agreement.txt"
 201 )
 202
 203 // NewServer constructs a new Server from a config dir
 204 // TODO: move config file reads out of this function
 205 func NewServer(configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
 206         server := Server{
 207                 NetInterface:  netInterface,
 208                 Port:          netPort,
 209                 Accounts:      make(map[string]*Account),
 210                 Config:        new(Config),
 211                 Clients:       make(map[[2]byte]*ClientConn),
 212                 fileTransfers: make(map[[4]byte]*FileTransfer),
 213                 PrivateChats:  make(map[[4]byte]*PrivateChat),
 214                 ConfigDir:     configDir,
 215                 Logger:        logger,
 216                 outbox:        make(chan Transaction),
 217                 Stats:         &Stats{Since: time.Now()},
 218                 ThreadedNews:  &ThreadedNews{},
 219                 FS:            fs,
 220                 banList:       make(map[string]*time.Time),
 221         }
 222
 223         var err error
 224
 225         // generate a new random passID for tracker registration
 226         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 227                 return nil, err
 228         }
 229
 230         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 231         if err != nil {
 232                 return nil, err
 233         }
 234
 235         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 236                 return nil, err
 237         }
 238
 239         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 240         //_ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 241
 242         _ = loadFromYAMLFile(filepath.Join(configDir, "Banlist.yaml"), &server.banList)
 243
 244         err = loadFromYAMLFile(filepath.Join(configDir, "ThreadedNews.yaml"), &server.ThreadedNews)
 245         if err != nil {
 246                 return nil, fmt.Errorf("error loading threaded news: %w", err)
 247         }
 248
 249         err = server.loadConfig(filepath.Join(configDir, "config.yaml"))
 250         if err != nil {
 251                 return nil, fmt.Errorf("error loading config: %w", err)
 252         }
 253
 254         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 255                 return nil, err
 256         }
 257
 258         // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
 259         if !filepath.IsAbs(server.Config.FileRoot) {
 260                 server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
 261         }
 262
 263         server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
 264         if err != nil {
 265                 return nil, fmt.Errorf("error opening banner: %w", err)
 266         }
 267
 268         if server.Config.EnableTrackerRegistration {
 269                 server.Logger.Info(
 270                         "Tracker registration enabled",
 271                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 272                         "trackers", server.Config.Trackers,
 273                 )
 274
 275                 go func() {
 276                         for {
 277                                 tr := &TrackerRegistration{
 278                                         UserCount:   server.userCount(),
 279                                         PassID:      server.TrackerPassID,
 280                                         Name:        server.Config.Name,
 281                                         Description: server.Config.Description,
 282                                 }
 283                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 284                                 for _, t := range server.Config.Trackers {
 285                                         if err := register(&RealDialer{}, t, tr); err != nil {
 286                                                 server.Logger.Error("unable to register with tracker %v", "error", err)
 287                                         }
 288                                         server.Logger.Debug("Sent Tracker registration", "addr", t)
 289                                 }
 290
 291                                 time.Sleep(trackerUpdateFrequency * time.Second)
 292                         }
 293                 }()
 294         }
 295
 296         // Start Client Keepalive go routine
 297         go server.keepaliveHandler()
 298
 299         return &server, nil
 300 }
 301
 302 func (s *Server) userCount() int {
 303         s.mux.Lock()
 304         defer s.mux.Unlock()
 305
 306         return len(s.Clients)
 307 }
 308
 309 func (s *Server) keepaliveHandler() {
 310         for {
 311                 time.Sleep(idleCheckInterval * time.Second)
 312                 s.mux.Lock()
 313
 314                 for _, c := range s.Clients {
 315                         c.IdleTime += idleCheckInterval
 316                         if c.IdleTime > userIdleSeconds && !c.Idle {
 317                                 c.Idle = true
 318
 319                                 c.flagsMU.Lock()
 320                                 c.Flags.Set(UserFlagAway, 1)
 321                                 c.flagsMU.Unlock()
 322                                 c.sendAll(
 323                                         TranNotifyChangeUser,
 324                                         NewField(FieldUserID, c.ID[:]),
 325                                         NewField(FieldUserFlags, c.Flags[:]),
 326                                         NewField(FieldUserName, c.UserName),
 327                                         NewField(FieldUserIconID, c.Icon),
 328                                 )
 329                         }
 330                 }
 331                 s.mux.Unlock()
 332         }
 333 }
 334
 335 func (s *Server) writeBanList() error {
 336         s.banListMU.Lock()
 337         defer s.banListMU.Unlock()
 338
 339         out, err := yaml.Marshal(s.banList)
 340         if err != nil {
 341                 return err
 342         }
 343         err = os.WriteFile(
 344                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 345                 out,
 346                 0666,
 347         )
 348         return err
 349 }
 350
 351 func (s *Server) writeThreadedNews() error {
 352         s.threadedNewsMux.Lock()
 353         defer s.threadedNewsMux.Unlock()
 354
 355         out, err := yaml.Marshal(s.ThreadedNews)
 356         if err != nil {
 357                 return err
 358         }
 359         err = s.FS.WriteFile(
 360                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 361                 out,
 362                 0666,
 363         )
 364         return err
 365 }
 366
 367 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 368         s.mux.Lock()
 369         defer s.mux.Unlock()
 370
 371         clientConn := &ClientConn{
 372                 Icon:       []byte{0, 0}, // TODO: make array type
 373                 Connection: conn,
 374                 Server:     s,
 375                 RemoteAddr: remoteAddr,
 376                 transfers: map[int]map[[4]byte]*FileTransfer{
 377                         FileDownload:   {},
 378                         FileUpload:     {},
 379                         FolderDownload: {},
 380                         FolderUpload:   {},
 381                         bannerDownload: {},
 382                 },
 383         }
 384
 385         s.nextClientID.Add(1)
 386
 387         binary.BigEndian.PutUint16(clientConn.ID[:], uint16(s.nextClientID.Load()))
 388         s.Clients[clientConn.ID] = clientConn
 389
 390         return clientConn
 391 }
 392
 393 // NewUser creates a new user account entry in the server map and config file
 394 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 395         s.mux.Lock()
 396         defer s.mux.Unlock()
 397
 398         account := NewAccount(login, name, password, access)
 399
 400         // Create account file, returning an error if one already exists.
 401         file, err := os.OpenFile(
 402                 filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
 403                 os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644,
 404         )
 405         if err != nil {
 406                 return fmt.Errorf("error creating account file: %w", err)
 407         }
 408         defer file.Close()
 409
 410         b, err := yaml.Marshal(account)
 411         if err != nil {
 412                 return err
 413         }
 414
 415         _, err = file.Write(b)
 416         if err != nil {
 417                 return fmt.Errorf("error writing account file: %w", err)
 418         }
 419
 420         s.Accounts[login] = account
 421
 422         return nil
 423 }
 424
 425 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 426         s.mux.Lock()
 427         defer s.mux.Unlock()
 428
 429         // If the login has changed, rename the account file.
 430         if login != newLogin {
 431                 err := os.Rename(
 432                         filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
 433                         filepath.Join(s.ConfigDir, "Users", path.Join("/", newLogin)+".yaml"),
 434                 )
 435                 if err != nil {
 436                         return fmt.Errorf("error renaming account file: %w", err)
 437                 }
 438                 s.Accounts[newLogin] = s.Accounts[login]
 439                 s.Accounts[newLogin].Login = newLogin
 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 fmt.Errorf("error writing account file: %w", 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         err := s.FS.Remove(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"))
 466         if err != nil {
 467                 return err
 468         }
 469
 470         delete(s.Accounts, login)
 471
 472         return nil
 473 }
 474
 475 func (s *Server) connectedUsers() []Field {
 476         //s.mux.Lock()
 477         //defer s.mux.Unlock()
 478
 479         var connectedUsers []Field
 480         for _, c := range sortedClients(s.Clients) {
 481                 b, err := io.ReadAll(&User{
 482                         ID:    c.ID,
 483                         Icon:  c.Icon,
 484                         Flags: c.Flags[:],
 485                         Name:  string(c.UserName),
 486                 })
 487                 if err != nil {
 488                         return nil
 489                 }
 490                 connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, b))
 491         }
 492         return connectedUsers
 493 }
 494
 495 // loadFromYAMLFile loads data from a YAML file into the provided data structure.
 496 func loadFromYAMLFile(path string, data interface{}) error {
 497         fh, err := os.Open(path)
 498         if err != nil {
 499                 return err
 500         }
 501         defer fh.Close()
 502
 503         decoder := yaml.NewDecoder(fh)
 504         return decoder.Decode(data)
 505 }
 506
 507 // loadAccounts loads account data from disk
 508 func (s *Server) loadAccounts(userDir string) error {
 509         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 510         if err != nil {
 511                 return err
 512         }
 513
 514         if len(matches) == 0 {
 515                 return fmt.Errorf("no accounts found in directory: %s", userDir)
 516         }
 517
 518         for _, file := range matches {
 519                 var account Account
 520                 if err = loadFromYAMLFile(file, &account); err != nil {
 521                         return fmt.Errorf("error loading account %s: %w", file, err)
 522                 }
 523
 524                 s.Accounts[account.Login] = &account
 525         }
 526         return nil
 527 }
 528
 529 func (s *Server) loadConfig(path string) error {
 530         fh, err := s.FS.Open(path)
 531         if err != nil {
 532                 return err
 533         }
 534
 535         decoder := yaml.NewDecoder(fh)
 536         err = decoder.Decode(s.Config)
 537         if err != nil {
 538                 return err
 539         }
 540
 541         validate := validator.New()
 542         err = validate.Struct(s.Config)
 543         if err != nil {
 544                 return err
 545         }
 546         return nil
 547 }
 548
 549 func sendBanMessage(rwc io.Writer, message string) {
 550         t := NewTransaction(
 551                 TranServerMsg,
 552                 [2]byte{0, 0},
 553                 NewField(FieldData, []byte(message)),
 554                 NewField(FieldChatOptions, []byte{0, 0}),
 555         )
 556         _, _ = io.Copy(rwc, &t)
 557         time.Sleep(1 * time.Second)
 558 }
 559
 560 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 561 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 562         defer dontPanic(s.Logger)
 563
 564         // Check if remoteAddr is present in the ban list
 565         ipAddr := strings.Split(remoteAddr, ":")[0]
 566         if banUntil, ok := s.banList[ipAddr]; ok {
 567                 // permaban
 568                 if banUntil == nil {
 569                         sendBanMessage(rwc, "You are permanently banned on this server")
 570                         s.Logger.Debug("Disconnecting permanently banned IP", "remoteAddr", ipAddr)
 571                         return nil
 572                 }
 573
 574                 // temporary ban
 575                 if time.Now().Before(*banUntil) {
 576                         sendBanMessage(rwc, "You are temporarily banned on this server")
 577                         s.Logger.Debug("Disconnecting temporarily banned IP", "remoteAddr", ipAddr)
 578                         return nil
 579                 }
 580         }
 581
 582         if err := performHandshake(rwc); err != nil {
 583                 return fmt.Errorf("error performing handshake: %w", err)
 584         }
 585
 586         // Create a new scanner for parsing incoming bytes into transaction tokens
 587         scanner := bufio.NewScanner(rwc)
 588         scanner.Split(transactionScanner)
 589
 590         scanner.Scan()
 591
 592         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 593         // scanner re-uses the buffer for subsequent scans.
 594         buf := make([]byte, len(scanner.Bytes()))
 595         copy(buf, scanner.Bytes())
 596
 597         var clientLogin Transaction
 598         if _, err := clientLogin.Write(buf); err != nil {
 599                 return fmt.Errorf("error writing login transaction: %w", err)
 600         }
 601
 602         c := s.NewClientConn(rwc, remoteAddr)
 603         defer c.Disconnect()
 604
 605         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 606         c.Version = clientLogin.GetField(FieldVersion).Data
 607
 608         login := string(encodeString(clientLogin.GetField(FieldUserLogin).Data))
 609         if login == "" {
 610                 login = GuestAccount
 611         }
 612
 613         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 614
 615         // If authentication fails, send error reply and close connection
 616         if !c.Authenticate(login, encodedPassword) {
 617                 t := c.NewErrReply(&clientLogin, "Incorrect login.")[0]
 618
 619                 _, err := io.Copy(rwc, &t)
 620                 if err != nil {
 621                         return err
 622                 }
 623
 624                 c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 625
 626                 return nil
 627         }
 628
 629         if clientLogin.GetField(FieldUserIconID).Data != nil {
 630                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 631         }
 632
 633         c.Lock()
 634         c.Account = c.Server.Accounts[login]
 635         c.Unlock()
 636
 637         if clientLogin.GetField(FieldUserName).Data != nil {
 638                 if c.Authorize(accessAnyName) {
 639                         c.UserName = clientLogin.GetField(FieldUserName).Data
 640                 } else {
 641                         c.UserName = []byte(c.Account.Name)
 642                 }
 643         }
 644
 645         if c.Authorize(accessDisconUser) {
 646                 c.Flags.Set(UserFlagAdmin, 1)
 647         }
 648
 649         s.outbox <- c.NewReply(&clientLogin,
 650                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 651                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 652                 NewField(FieldServerName, []byte(s.Config.Name)),
 653         )
 654
 655         // Send user access privs so client UI knows how to behave
 656         c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 657
 658         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 659         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 660         // TranShowAgreement but with the NoServerAgreement field set to 1.
 661         if c.Authorize(accessNoAgreement) {
 662                 // If client version is nil, then the client uses the 1.2.3 login behavior
 663                 if c.Version != nil {
 664                         c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 665                 }
 666         } else {
 667                 c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
 668         }
 669
 670         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 671         // flow and not the 1.5+ flow.
 672         if len(c.UserName) != 0 {
 673                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 674                 // part of TranAgreed
 675                 c.logger = c.logger.With("Name", string(c.UserName))
 676                 c.logger.Info("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
 677
 678                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 679                 // information yet, so we do it in TranAgreed instead
 680                 for _, t := range c.notifyOthers(
 681                         NewTransaction(
 682                                 TranNotifyChangeUser, [2]byte{0, 0},
 683                                 NewField(FieldUserName, c.UserName),
 684                                 NewField(FieldUserID, c.ID[:]),
 685                                 NewField(FieldUserIconID, c.Icon),
 686                                 NewField(FieldUserFlags, c.Flags[:]),
 687                         ),
 688                 ) {
 689                         c.Server.outbox <- t
 690                 }
 691         }
 692
 693         c.Server.mux.Lock()
 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         c.Server.mux.Unlock()
 699
 700         // Scan for new transactions and handle them as they come in.
 701         for scanner.Scan() {
 702                 // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
 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                 c.handleTransaction(t)
 712         }
 713         return nil
 714 }
 715
 716 func (s *Server) NewPrivateChat(cc *ClientConn) [4]byte {
 717         s.PrivateChatsMu.Lock()
 718         defer s.PrivateChatsMu.Unlock()
 719
 720         var randID [4]byte
 721         _, _ = rand.Read(randID[:])
 722
 723         s.PrivateChats[randID] = &PrivateChat{
 724                 ClientConn: make(map[[2]byte]*ClientConn),
 725         }
 726         s.PrivateChats[randID].ClientConn[cc.ID] = cc
 727
 728         return randID
 729 }
 730
 731 const dlFldrActionSendFile = 1
 732 const dlFldrActionResumeFile = 2
 733 const dlFldrActionNextFile = 3
 734
 735 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 736 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 737         defer dontPanic(s.Logger)
 738
 739         // The first 16 bytes contain the file transfer.
 740         var t transfer
 741         if _, err := io.CopyN(&t, rwc, 16); err != nil {
 742                 return fmt.Errorf("error reading file transfer: %w", err)
 743         }
 744
 745         defer func() {
 746                 s.mux.Lock()
 747                 delete(s.fileTransfers, t.ReferenceNumber)
 748                 s.mux.Unlock()
 749
 750                 // Wait a few seconds before closing the connection: this is a workaround for problems
 751                 // observed with Windows clients where the client must initiate close of the TCP connection before
 752                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 753                 time.Sleep(3 * time.Second)
 754         }()
 755
 756         s.mux.Lock()
 757         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 758         s.mux.Unlock()
 759         if !ok {
 760                 return errors.New("invalid transaction ID")
 761         }
 762
 763         defer func() {
 764                 fileTransfer.ClientConn.transfersMU.Lock()
 765                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 766                 fileTransfer.ClientConn.transfersMU.Unlock()
 767         }()
 768
 769         rLogger := s.Logger.With(
 770                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 771                 "login", fileTransfer.ClientConn.Account.Login,
 772                 "Name", string(fileTransfer.ClientConn.UserName),
 773         )
 774
 775         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 776         if err != nil {
 777                 return err
 778         }
 779
 780         switch fileTransfer.Type {
 781         case bannerDownload:
 782                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
 783                         return fmt.Errorf("error sending banner: %w", err)
 784                 }
 785         case FileDownload:
 786                 s.Stats.DownloadCounter += 1
 787                 s.Stats.DownloadsInProgress += 1
 788                 defer func() {
 789                         s.Stats.DownloadsInProgress -= 1
 790                 }()
 791
 792                 err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
 793                 if err != nil {
 794                         return fmt.Errorf("file download error: %w", err)
 795                 }
 796
 797         case FileUpload:
 798                 s.Stats.UploadCounter += 1
 799                 s.Stats.UploadsInProgress += 1
 800                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 801
 802                 err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 803                 if err != nil {
 804                         return fmt.Errorf("file upload error: %w", err)
 805                 }
 806
 807         case FolderDownload:
 808                 s.Stats.DownloadCounter += 1
 809                 s.Stats.DownloadsInProgress += 1
 810                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 811
 812                 err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 813                 if err != nil {
 814                         return fmt.Errorf("file upload error: %w", err)
 815                 }
 816
 817         case FolderUpload:
 818                 s.Stats.UploadCounter += 1
 819                 s.Stats.UploadsInProgress += 1
 820                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 821                 rLogger.Info(
 822                         "Folder upload started",
 823                         "dstPath", fullPath,
 824                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
 825                         "FolderItemCount", fileTransfer.FolderItemCount,
 826                 )
 827
 828                 err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 829                 if err != nil {
 830                         return fmt.Errorf("file upload error: %w", err)
 831                 }
 832         }
 833         return nil
 834 }