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         "golang.org/x/text/encoding/charmap"
  12         "gopkg.in/yaml.v3"
  13         "io"
  14         "io/fs"
  15         "log"
  16         "log/slog"
  17         "math/big"
  18         "math/rand"
  19         "net"
  20         "os"
  21         "path"
  22         "path/filepath"
  23         "strings"
  24         "sync"
  25         "time"
  26 )
  27
  28 type contextKey string
  29
  30 var contextKeyReq = contextKey("req")
  31
  32 type requestCtx struct {
  33         remoteAddr string
  34 }
  35
  36 // Converts bytes from Mac Roman encoding to UTF-8
  37 var txtDecoder = charmap.Macintosh.NewDecoder()
  38
  39 // Converts bytes from UTF-8 to Mac Roman encoding
  40 var txtEncoder = charmap.Macintosh.NewEncoder()
  41
  42 type Server struct {
  43         NetInterface  string
  44         Port          int
  45         Accounts      map[string]*Account
  46         Agreement     []byte
  47         Clients       map[uint16]*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[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.Info("Hotline server started",
  96                 "version", VERSION,
  97                 "API port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port),
  98                 "Transfer port", fmt.Sprintf("%s:%v", s.NetInterface, 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.NetInterface, s.Port))
 106                 if err != nil {
 107                         log.Fatal(err)
 108                 }
 109
 110                 log.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.NetInterface, s.Port+1))
 116                 if err != nil {
 117                         log.Fatal(err)
 118                 }
 119
 120                 log.Fatal(s.ServeFileTransfers(ctx, ln))
 121         }()
 122
 123         wg.Wait()
 124
 125         return nil
 126 }
 127
 128 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 129         for {
 130                 conn, err := ln.Accept()
 131                 if err != nil {
 132                         return err
 133                 }
 134
 135                 go func() {
 136                         defer func() { _ = conn.Close() }()
 137
 138                         err = s.handleFileTransfer(
 139                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 140                                         remoteAddr: conn.RemoteAddr().String(),
 141                                 }),
 142                                 conn,
 143                         )
 144
 145                         if err != nil {
 146                                 s.Logger.Error("file transfer error", "reason", err)
 147                         }
 148                 }()
 149         }
 150 }
 151
 152 func (s *Server) sendTransaction(t Transaction) error {
 153         clientID, err := byteToInt(*t.clientID)
 154         if err != nil {
 155                 return err
 156         }
 157
 158         s.mux.Lock()
 159         client := s.Clients[uint16(clientID)]
 160         s.mux.Unlock()
 161         if client == nil {
 162                 return fmt.Errorf("invalid client id %v", *t.clientID)
 163         }
 164
 165         b, err := t.MarshalBinary()
 166         if err != nil {
 167                 return err
 168         }
 169
 170         _, err = client.Connection.Write(b)
 171         if err != nil {
 172                 return err
 173         }
 174
 175         return nil
 176 }
 177
 178 func (s *Server) processOutbox() {
 179         for {
 180                 t := <-s.outbox
 181                 go func() {
 182                         if err := s.sendTransaction(t); err != nil {
 183                                 s.Logger.Error("error sending transaction", "err", err)
 184                         }
 185                 }()
 186         }
 187 }
 188
 189 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 190         go s.processOutbox()
 191
 192         for {
 193                 conn, err := ln.Accept()
 194                 if err != nil {
 195                         s.Logger.Error("error accepting connection", "err", err)
 196                 }
 197                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 198                         remoteAddr: conn.RemoteAddr().String(),
 199                 })
 200
 201                 go func() {
 202                         s.Logger.Info("Connection established", "RemoteAddr", conn.RemoteAddr())
 203
 204                         defer conn.Close()
 205                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 206                                 if err == io.EOF {
 207                                         s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 208                                 } else {
 209                                         s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 210                                 }
 211                         }
 212                 }()
 213         }
 214 }
 215
 216 const (
 217         agreementFile = "Agreement.txt"
 218 )
 219
 220 // NewServer constructs a new Server from a config dir
 221 func NewServer(configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
 222         server := Server{
 223                 NetInterface:  netInterface,
 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         // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
 272         if !filepath.IsAbs(server.Config.FileRoot) {
 273                 server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
 274         }
 275
 276         server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
 277         if err != nil {
 278                 return nil, fmt.Errorf("error opening banner: %w", err)
 279         }
 280
 281         *server.NextGuestID = 1
 282
 283         if server.Config.EnableTrackerRegistration {
 284                 server.Logger.Info(
 285                         "Tracker registration enabled",
 286                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 287                         "trackers", server.Config.Trackers,
 288                 )
 289
 290                 go func() {
 291                         for {
 292                                 tr := &TrackerRegistration{
 293                                         UserCount:   server.userCount(),
 294                                         PassID:      server.TrackerPassID,
 295                                         Name:        server.Config.Name,
 296                                         Description: server.Config.Description,
 297                                 }
 298                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 299                                 for _, t := range server.Config.Trackers {
 300                                         if err := register(t, tr); err != nil {
 301                                                 server.Logger.Error("unable to register with tracker %v", "error", err)
 302                                         }
 303                                         server.Logger.Debug("Sent Tracker registration", "addr", t)
 304                                 }
 305
 306                                 time.Sleep(trackerUpdateFrequency * time.Second)
 307                         }
 308                 }()
 309         }
 310
 311         // Start Client Keepalive go routine
 312         go server.keepaliveHandler()
 313
 314         return &server, nil
 315 }
 316
 317 func (s *Server) userCount() int {
 318         s.mux.Lock()
 319         defer s.mux.Unlock()
 320
 321         return len(s.Clients)
 322 }
 323
 324 func (s *Server) keepaliveHandler() {
 325         for {
 326                 time.Sleep(idleCheckInterval * time.Second)
 327                 s.mux.Lock()
 328
 329                 for _, c := range s.Clients {
 330                         c.IdleTime += idleCheckInterval
 331                         if c.IdleTime > userIdleSeconds && !c.Idle {
 332                                 c.Idle = true
 333
 334                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 335                                 flagBitmap.SetBit(flagBitmap, UserFlagAway, 1)
 336                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 337
 338                                 c.sendAll(
 339                                         TranNotifyChangeUser,
 340                                         NewField(FieldUserID, *c.ID),
 341                                         NewField(FieldUserFlags, c.Flags),
 342                                         NewField(FieldUserName, c.UserName),
 343                                         NewField(FieldUserIconID, c.Icon),
 344                                 )
 345                         }
 346                 }
 347                 s.mux.Unlock()
 348         }
 349 }
 350
 351 func (s *Server) writeBanList() error {
 352         s.banListMU.Lock()
 353         defer s.banListMU.Unlock()
 354
 355         out, err := yaml.Marshal(s.banList)
 356         if err != nil {
 357                 return err
 358         }
 359         err = os.WriteFile(
 360                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 361                 out,
 362                 0666,
 363         )
 364         return err
 365 }
 366
 367 func (s *Server) writeThreadedNews() error {
 368         s.threadedNewsMux.Lock()
 369         defer s.threadedNewsMux.Unlock()
 370
 371         out, err := yaml.Marshal(s.ThreadedNews)
 372         if err != nil {
 373                 return err
 374         }
 375         err = s.FS.WriteFile(
 376                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 377                 out,
 378                 0666,
 379         )
 380         return err
 381 }
 382
 383 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 384         s.mux.Lock()
 385         defer s.mux.Unlock()
 386
 387         clientConn := &ClientConn{
 388                 ID:         &[]byte{0, 0},
 389                 Icon:       []byte{0, 0},
 390                 Flags:      []byte{0, 0},
 391                 UserName:   []byte{},
 392                 Connection: conn,
 393                 Server:     s,
 394                 Version:    []byte{},
 395                 AutoReply:  []byte{},
 396                 RemoteAddr: remoteAddr,
 397                 transfers: map[int]map[[4]byte]*FileTransfer{
 398                         FileDownload:   {},
 399                         FileUpload:     {},
 400                         FolderDownload: {},
 401                         FolderUpload:   {},
 402                         bannerDownload: {},
 403                 },
 404         }
 405
 406         *s.NextGuestID++
 407         ID := *s.NextGuestID
 408
 409         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 410         s.Clients[ID] = clientConn
 411
 412         return clientConn
 413 }
 414
 415 // NewUser creates a new user account entry in the server map and config file
 416 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 417         s.mux.Lock()
 418         defer s.mux.Unlock()
 419
 420         account := Account{
 421                 Login:    login,
 422                 Name:     name,
 423                 Password: hashAndSalt([]byte(password)),
 424                 Access:   access,
 425         }
 426         out, err := yaml.Marshal(&account)
 427         if err != nil {
 428                 return err
 429         }
 430
 431         // Create account file, returning an error if one already exists.
 432         file, err := os.OpenFile(
 433                 filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
 434                 os.O_CREATE|os.O_EXCL|os.O_WRONLY,
 435                 0644,
 436         )
 437         if err != nil {
 438                 return err
 439         }
 440         defer file.Close()
 441
 442         _, err = file.Write(out)
 443         if err != nil {
 444                 return fmt.Errorf("error writing account file: %w", err)
 445         }
 446
 447         s.Accounts[login] = &account
 448
 449         return nil
 450 }
 451
 452 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 453         s.mux.Lock()
 454         defer s.mux.Unlock()
 455
 456         // update renames the user login
 457         if login != newLogin {
 458                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"), filepath.Join(s.ConfigDir, "Users", path.Join("/", newLogin)+".yaml"))
 459                 if err != nil {
 460                         return fmt.Errorf("unable to rename account: %w", err)
 461                 }
 462                 s.Accounts[newLogin] = s.Accounts[login]
 463                 s.Accounts[newLogin].Login = newLogin
 464                 delete(s.Accounts, login)
 465         }
 466
 467         account := s.Accounts[newLogin]
 468         account.Access = access
 469         account.Name = name
 470         account.Password = password
 471
 472         out, err := yaml.Marshal(&account)
 473         if err != nil {
 474                 return err
 475         }
 476
 477         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 478                 return err
 479         }
 480
 481         return nil
 482 }
 483
 484 // DeleteUser deletes the user account
 485 func (s *Server) DeleteUser(login string) error {
 486         s.mux.Lock()
 487         defer s.mux.Unlock()
 488
 489         err := s.FS.Remove(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"))
 490         if err != nil {
 491                 return err
 492         }
 493
 494         delete(s.Accounts, login)
 495
 496         return nil
 497 }
 498
 499 func (s *Server) connectedUsers() []Field {
 500         s.mux.Lock()
 501         defer s.mux.Unlock()
 502
 503         var connectedUsers []Field
 504         for _, c := range sortedClients(s.Clients) {
 505                 b, err := io.ReadAll(&User{
 506                         ID:    *c.ID,
 507                         Icon:  c.Icon,
 508                         Flags: c.Flags,
 509                         Name:  string(c.UserName),
 510                 })
 511                 if err != nil {
 512                         return nil
 513                 }
 514                 connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, b))
 515         }
 516         return connectedUsers
 517 }
 518
 519 func (s *Server) loadBanList(path string) error {
 520         fh, err := os.Open(path)
 521         if err != nil {
 522                 return err
 523         }
 524         decoder := yaml.NewDecoder(fh)
 525
 526         return decoder.Decode(s.banList)
 527 }
 528
 529 // loadThreadedNews loads the threaded news data from disk
 530 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 531         fh, err := os.Open(threadedNewsPath)
 532         if err != nil {
 533                 return err
 534         }
 535         decoder := yaml.NewDecoder(fh)
 536
 537         return decoder.Decode(s.ThreadedNews)
 538 }
 539
 540 // loadAccounts loads account data from disk
 541 func (s *Server) loadAccounts(userDir string) error {
 542         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 543         if err != nil {
 544                 return err
 545         }
 546
 547         if len(matches) == 0 {
 548                 return errors.New("no user accounts found in " + userDir)
 549         }
 550
 551         for _, file := range matches {
 552                 fh, err := s.FS.Open(file)
 553                 if err != nil {
 554                         return err
 555                 }
 556
 557                 account := Account{}
 558                 decoder := yaml.NewDecoder(fh)
 559                 if err = decoder.Decode(&account); err != nil {
 560                         return fmt.Errorf("error loading account %s: %w", file, err)
 561                 }
 562
 563                 s.Accounts[account.Login] = &account
 564         }
 565         return nil
 566 }
 567
 568 func (s *Server) loadConfig(path string) error {
 569         fh, err := s.FS.Open(path)
 570         if err != nil {
 571                 return err
 572         }
 573
 574         decoder := yaml.NewDecoder(fh)
 575         err = decoder.Decode(s.Config)
 576         if err != nil {
 577                 return err
 578         }
 579
 580         validate := validator.New()
 581         err = validate.Struct(s.Config)
 582         if err != nil {
 583                 return err
 584         }
 585         return nil
 586 }
 587
 588 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 589 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 590         defer dontPanic(s.Logger)
 591
 592         if err := Handshake(rwc); err != nil {
 593                 return err
 594         }
 595
 596         // Create a new scanner for parsing incoming bytes into transaction tokens
 597         scanner := bufio.NewScanner(rwc)
 598         scanner.Split(transactionScanner)
 599
 600         scanner.Scan()
 601
 602         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 603         // scanner re-uses the buffer for subsequent scans.
 604         buf := make([]byte, len(scanner.Bytes()))
 605         copy(buf, scanner.Bytes())
 606
 607         var clientLogin Transaction
 608         if _, err := clientLogin.Write(buf); err != nil {
 609                 return err
 610         }
 611
 612         // check if remoteAddr is present in the ban list
 613         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 614                 // permaban
 615                 if banUntil == nil {
 616                         t := NewTransaction(
 617                                 TranServerMsg,
 618                                 &[]byte{0, 0},
 619                                 NewField(FieldData, []byte("You are permanently banned on this server")),
 620                                 NewField(FieldChatOptions, []byte{0, 0}),
 621                         )
 622
 623                         b, err := t.MarshalBinary()
 624                         if err != nil {
 625                                 return err
 626                         }
 627
 628                         _, err = rwc.Write(b)
 629                         if err != nil {
 630                                 return err
 631                         }
 632
 633                         time.Sleep(1 * time.Second)
 634                         return nil
 635                 }
 636
 637                 // temporary ban
 638                 if time.Now().Before(*banUntil) {
 639                         t := NewTransaction(
 640                                 TranServerMsg,
 641                                 &[]byte{0, 0},
 642                                 NewField(FieldData, []byte("You are temporarily banned on this server")),
 643                                 NewField(FieldChatOptions, []byte{0, 0}),
 644                         )
 645                         b, err := t.MarshalBinary()
 646                         if err != nil {
 647                                 return err
 648                         }
 649
 650                         _, err = rwc.Write(b)
 651                         if err != nil {
 652                                 return err
 653                         }
 654
 655                         time.Sleep(1 * time.Second)
 656                         return nil
 657                 }
 658         }
 659
 660         c := s.NewClientConn(rwc, remoteAddr)
 661         defer c.Disconnect()
 662
 663         encodedLogin := clientLogin.GetField(FieldUserLogin).Data
 664         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 665         c.Version = clientLogin.GetField(FieldVersion).Data
 666
 667         var login string
 668         for _, char := range encodedLogin {
 669                 login += string(rune(255 - uint(char)))
 670         }
 671         if login == "" {
 672                 login = GuestAccount
 673         }
 674
 675         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 676
 677         // If authentication fails, send error reply and close connection
 678         if !c.Authenticate(login, encodedPassword) {
 679                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 680                 b, err := t.MarshalBinary()
 681                 if err != nil {
 682                         return err
 683                 }
 684                 if _, err := rwc.Write(b); err != nil {
 685                         return err
 686                 }
 687
 688                 c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 689
 690                 return nil
 691         }
 692
 693         if clientLogin.GetField(FieldUserIconID).Data != nil {
 694                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 695         }
 696
 697         c.Account = c.Server.Accounts[login]
 698
 699         if clientLogin.GetField(FieldUserName).Data != nil {
 700                 if c.Authorize(accessAnyName) {
 701                         c.UserName = clientLogin.GetField(FieldUserName).Data
 702                 } else {
 703                         c.UserName = []byte(c.Account.Name)
 704                 }
 705         }
 706
 707         if c.Authorize(accessDisconUser) {
 708                 c.Flags = []byte{0, 2}
 709         }
 710
 711         s.outbox <- c.NewReply(&clientLogin,
 712                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 713                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 714                 NewField(FieldServerName, []byte(s.Config.Name)),
 715         )
 716
 717         // Send user access privs so client UI knows how to behave
 718         c.Server.outbox <- *NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 719
 720         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 721         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 722         // TranShowAgreement but with the NoServerAgreement field set to 1.
 723         if c.Authorize(accessNoAgreement) {
 724                 // If client version is nil, then the client uses the 1.2.3 login behavior
 725                 if c.Version != nil {
 726                         c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 727                 }
 728         } else {
 729                 c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
 730         }
 731
 732         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 733         // flow and not the 1.5+ flow.
 734         if len(c.UserName) != 0 {
 735                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 736                 // part of TranAgreed
 737                 c.logger = c.logger.With("name", string(c.UserName))
 738
 739                 c.logger.Info("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
 740
 741                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 742                 // information yet, so we do it in TranAgreed instead
 743                 for _, t := range c.notifyOthers(
 744                         *NewTransaction(
 745                                 TranNotifyChangeUser, nil,
 746                                 NewField(FieldUserName, c.UserName),
 747                                 NewField(FieldUserID, *c.ID),
 748                                 NewField(FieldUserIconID, c.Icon),
 749                                 NewField(FieldUserFlags, c.Flags),
 750                         ),
 751                 ) {
 752                         c.Server.outbox <- t
 753                 }
 754         }
 755
 756         c.Server.Stats.ConnectionCounter += 1
 757         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 758                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 759         }
 760
 761         // Scan for new transactions and handle them as they come in.
 762         for scanner.Scan() {
 763                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 764                 // scanner re-uses the buffer for subsequent scans.
 765                 buf := make([]byte, len(scanner.Bytes()))
 766                 copy(buf, scanner.Bytes())
 767
 768                 var t Transaction
 769                 if _, err := t.Write(buf); err != nil {
 770                         return err
 771                 }
 772
 773                 if err := c.handleTransaction(t); err != nil {
 774                         c.logger.Error("Error handling transaction", "err", err)
 775                 }
 776         }
 777         return nil
 778 }
 779
 780 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 781         s.PrivateChatsMu.Lock()
 782         defer s.PrivateChatsMu.Unlock()
 783
 784         randID := make([]byte, 4)
 785         rand.Read(randID)
 786         data := binary.BigEndian.Uint32(randID)
 787
 788         s.PrivateChats[data] = &PrivateChat{
 789                 ClientConn: make(map[uint16]*ClientConn),
 790         }
 791         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 792
 793         return randID
 794 }
 795
 796 const dlFldrActionSendFile = 1
 797 const dlFldrActionResumeFile = 2
 798 const dlFldrActionNextFile = 3
 799
 800 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 801 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 802         defer dontPanic(s.Logger)
 803
 804         txBuf := make([]byte, 16)
 805         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 806                 return err
 807         }
 808
 809         var t transfer
 810         if _, err := t.Write(txBuf); err != nil {
 811                 return err
 812         }
 813
 814         defer func() {
 815                 s.mux.Lock()
 816                 delete(s.fileTransfers, t.ReferenceNumber)
 817                 s.mux.Unlock()
 818
 819                 // Wait a few seconds before closing the connection: this is a workaround for problems
 820                 // observed with Windows clients where the client must initiate close of the TCP connection before
 821                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 822                 time.Sleep(3 * time.Second)
 823         }()
 824
 825         s.mux.Lock()
 826         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 827         s.mux.Unlock()
 828         if !ok {
 829                 return errors.New("invalid transaction ID")
 830         }
 831
 832         defer func() {
 833                 fileTransfer.ClientConn.transfersMU.Lock()
 834                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 835                 fileTransfer.ClientConn.transfersMU.Unlock()
 836         }()
 837
 838         rLogger := s.Logger.With(
 839                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 840                 "login", fileTransfer.ClientConn.Account.Login,
 841                 "name", string(fileTransfer.ClientConn.UserName),
 842         )
 843
 844         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 845         if err != nil {
 846                 return err
 847         }
 848
 849         switch fileTransfer.Type {
 850         case bannerDownload:
 851                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
 852                         return fmt.Errorf("error sending banner: %w", err)
 853                 }
 854         case FileDownload:
 855                 s.Stats.DownloadCounter += 1
 856                 s.Stats.DownloadsInProgress += 1
 857                 defer func() {
 858                         s.Stats.DownloadsInProgress -= 1
 859                 }()
 860
 861                 var dataOffset int64
 862                 if fileTransfer.fileResumeData != nil {
 863                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 864                 }
 865
 866                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 867                 if err != nil {
 868                         return err
 869                 }
 870
 871                 rLogger.Info("File download started", "filePath", fullPath)
 872
 873                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 874                 if fileTransfer.options == nil {
 875                         _, err = io.Copy(rwc, fw.ffo)
 876                         if err != nil {
 877                                 return err
 878                         }
 879                 }
 880
 881                 file, err := fw.dataForkReader()
 882                 if err != nil {
 883                         return err
 884                 }
 885
 886                 br := bufio.NewReader(file)
 887                 if _, err := br.Discard(int(dataOffset)); err != nil {
 888                         return err
 889                 }
 890
 891                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 892                         return err
 893                 }
 894
 895                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 896                 if fileTransfer.fileResumeData == nil {
 897                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 898                         if err != nil {
 899                                 return err
 900                         }
 901                 }
 902
 903                 rFile, err := fw.rsrcForkFile()
 904                 if err != nil {
 905                         return nil
 906                 }
 907
 908                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 909                         return err
 910                 }
 911
 912         case FileUpload:
 913                 s.Stats.UploadCounter += 1
 914                 s.Stats.UploadsInProgress += 1
 915                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 916
 917                 var file *os.File
 918
 919                 // A file upload has three possible cases:
 920                 // 1) Upload a new file
 921                 // 2) Resume a partially transferred file
 922                 // 3) Replace a fully uploaded file
 923                 //  We have to infer which case applies by inspecting what is already on the filesystem
 924
 925                 // 1) Check for existing file:
 926                 _, err = os.Stat(fullPath)
 927                 if err == nil {
 928                         return errors.New("existing file found at " + fullPath)
 929                 }
 930                 if errors.Is(err, fs.ErrNotExist) {
 931                         // If not found, open or create a new .incomplete file
 932                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 933                         if err != nil {
 934                                 return err
 935                         }
 936                 }
 937
 938                 f, err := newFileWrapper(s.FS, fullPath, 0)
 939                 if err != nil {
 940                         return err
 941                 }
 942
 943                 rLogger.Info("File upload started", "dstFile", fullPath)
 944
 945                 rForkWriter := io.Discard
 946                 iForkWriter := io.Discard
 947                 if s.Config.PreserveResourceForks {
 948                         rForkWriter, err = f.rsrcForkWriter()
 949                         if err != nil {
 950                                 return err
 951                         }
 952
 953                         iForkWriter, err = f.infoForkWriter()
 954                         if err != nil {
 955                                 return err
 956                         }
 957                 }
 958
 959                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 960                         s.Logger.Error(err.Error())
 961                 }
 962
 963                 if err := file.Close(); err != nil {
 964                         return err
 965                 }
 966
 967                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 968                         return err
 969                 }
 970
 971                 rLogger.Info("File upload complete", "dstFile", fullPath)
 972
 973         case FolderDownload:
 974                 s.Stats.DownloadCounter += 1
 975                 s.Stats.DownloadsInProgress += 1
 976                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 977
 978                 // Folder Download flow:
 979                 // 1. Get filePath from the transfer
 980                 // 2. Iterate over files
 981                 // 3. For each fileWrapper:
 982                 //       Send fileWrapper header to client
 983                 // The client can reply in 3 ways:
 984                 //
 985                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 986                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 987                 //
 988                 // 2. If download of a fileWrapper is to be resumed:
 989                 //              client sends:
 990                 //                      []byte{0x00, 0x02} // download folder action
 991                 //                      [2]byte // Resume data size
 992                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 993                 //
 994                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 995                 //
 996                 // When download is requested (case 2 or 3), server replies with:
 997                 //                      [4]byte - fileWrapper size
 998                 //                      []byte  - Flattened File Object
 999                 //
1000                 // After every fileWrapper download, client could request next fileWrapper with:
1001                 //                      []byte{0x00, 0x03}
1002                 //
1003                 // This notifies the server to send the next item header
1004
1005                 basePathLen := len(fullPath)
1006
1007                 rLogger.Info("Start folder download", "path", fullPath)
1008
1009                 nextAction := make([]byte, 2)
1010                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
1011                         return err
1012                 }
1013
1014                 i := 0
1015                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
1016                         s.Stats.DownloadCounter += 1
1017                         i += 1
1018
1019                         if err != nil {
1020                                 return err
1021                         }
1022
1023                         // skip dot files
1024                         if strings.HasPrefix(info.Name(), ".") {
1025                                 return nil
1026                         }
1027
1028                         hlFile, err := newFileWrapper(s.FS, path, 0)
1029                         if err != nil {
1030                                 return err
1031                         }
1032
1033                         subPath := path[basePathLen+1:]
1034                         rLogger.Debug("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
1035
1036                         if i == 1 {
1037                                 return nil
1038                         }
1039
1040                         fileHeader := NewFileHeader(subPath, info.IsDir())
1041                         if _, err := io.Copy(rwc, &fileHeader); err != nil {
1042                                 return fmt.Errorf("error sending file header: %w", err)
1043                         }
1044
1045                         // Read the client's Next Action request
1046                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1047                                 return err
1048                         }
1049
1050                         rLogger.Debug("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
1051
1052                         var dataOffset int64
1053
1054                         switch nextAction[1] {
1055                         case dlFldrActionResumeFile:
1056                                 // get size of resumeData
1057                                 resumeDataByteLen := make([]byte, 2)
1058                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
1059                                         return err
1060                                 }
1061
1062                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
1063                                 resumeDataBytes := make([]byte, resumeDataLen)
1064                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
1065                                         return err
1066                                 }
1067
1068                                 var frd FileResumeData
1069                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1070                                         return err
1071                                 }
1072                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1073                         case dlFldrActionNextFile:
1074                                 // client asked to skip this file
1075                                 return nil
1076                         }
1077
1078                         if info.IsDir() {
1079                                 return nil
1080                         }
1081
1082                         rLogger.Info("File download started",
1083                                 "fileName", info.Name(),
1084                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1085                         )
1086
1087                         // Send file size to client
1088                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1089                                 s.Logger.Error(err.Error())
1090                                 return err
1091                         }
1092
1093                         // Send ffo bytes to client
1094                         _, err = io.Copy(rwc, hlFile.ffo)
1095                         if err != nil {
1096                                 return err
1097                         }
1098
1099                         file, err := s.FS.Open(path)
1100                         if err != nil {
1101                                 return err
1102                         }
1103
1104                         // wr := bufio.NewWriterSize(rwc, 1460)
1105                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1106                                 return err
1107                         }
1108
1109                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1110                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1111                                 if err != nil {
1112                                         return err
1113                                 }
1114
1115                                 rFile, err := hlFile.rsrcForkFile()
1116                                 if err != nil {
1117                                         return err
1118                                 }
1119
1120                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1121                                         return err
1122                                 }
1123                         }
1124
1125                         // Read the client's Next Action request.  This is always 3, I think?
1126                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1127                                 return err
1128                         }
1129
1130                         return nil
1131                 })
1132
1133                 if err != nil {
1134                         return err
1135                 }
1136
1137         case FolderUpload:
1138                 s.Stats.UploadCounter += 1
1139                 s.Stats.UploadsInProgress += 1
1140                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1141                 rLogger.Info(
1142                         "Folder upload started",
1143                         "dstPath", fullPath,
1144                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1145                         "FolderItemCount", fileTransfer.FolderItemCount,
1146                 )
1147
1148                 // Check if the target folder exists.  If not, create it.
1149                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1150                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1151                                 return err
1152                         }
1153                 }
1154
1155                 // Begin the folder upload flow by sending the "next file action" to client
1156                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1157                         return err
1158                 }
1159
1160                 fileSize := make([]byte, 4)
1161
1162                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1163                         s.Stats.UploadCounter += 1
1164
1165                         var fu folderUpload
1166                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1167                                 return err
1168                         }
1169                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1170                                 return err
1171                         }
1172                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1173                                 return err
1174                         }
1175
1176                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1177
1178                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1179                                 return err
1180                         }
1181
1182                         rLogger.Info(
1183                                 "Folder upload continued",
1184                                 "FormattedPath", fu.FormattedPath(),
1185                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1186                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1187                         )
1188
1189                         if fu.IsFolder == [2]byte{0, 1} {
1190                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1191                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1192                                                 return err
1193                                         }
1194                                 }
1195
1196                                 // Tell client to send next file
1197                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1198                                         return err
1199                                 }
1200                         } else {
1201                                 nextAction := dlFldrActionSendFile
1202
1203                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1204                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1205                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1206                                         return err
1207                                 }
1208                                 if err == nil {
1209                                         nextAction = dlFldrActionNextFile
1210                                 }
1211
1212                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1213                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1214                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1215                                         return err
1216                                 }
1217                                 if err == nil {
1218                                         nextAction = dlFldrActionResumeFile
1219                                 }
1220
1221                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1222                                         return err
1223                                 }
1224
1225                                 switch nextAction {
1226                                 case dlFldrActionNextFile:
1227                                         continue
1228                                 case dlFldrActionResumeFile:
1229                                         offset := make([]byte, 4)
1230                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1231
1232                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1233                                         if err != nil {
1234                                                 return err
1235                                         }
1236
1237                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1238
1239                                         b, _ := fileResumeData.BinaryMarshal()
1240
1241                                         bs := make([]byte, 2)
1242                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1243
1244                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1245                                                 return err
1246                                         }
1247
1248                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1249                                                 return err
1250                                         }
1251
1252                                         if err := receiveFile(rwc, file, io.Discard, io.Discard, fileTransfer.bytesSentCounter); err != nil {
1253                                                 s.Logger.Error(err.Error())
1254                                         }
1255
1256                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1257                                         if err != nil {
1258                                                 return err
1259                                         }
1260
1261                                 case dlFldrActionSendFile:
1262                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1263                                                 return err
1264                                         }
1265
1266                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1267
1268                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1269                                         if err != nil {
1270                                                 return err
1271                                         }
1272
1273                                         rLogger.Info("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1274
1275                                         incWriter, err := hlFile.incFileWriter()
1276                                         if err != nil {
1277                                                 return err
1278                                         }
1279
1280                                         rForkWriter := io.Discard
1281                                         iForkWriter := io.Discard
1282                                         if s.Config.PreserveResourceForks {
1283                                                 iForkWriter, err = hlFile.infoForkWriter()
1284                                                 if err != nil {
1285                                                         return err
1286                                                 }
1287
1288                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1289                                                 if err != nil {
1290                                                         return err
1291                                                 }
1292                                         }
1293                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1294                                                 return err
1295                                         }
1296
1297                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1298                                                 return err
1299                                         }
1300                                 }
1301
1302                                 // Tell client to send next fileWrapper
1303                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1304                                         return err
1305                                 }
1306                         }
1307                 }
1308                 rLogger.Info("Folder upload complete")
1309         }
1310
1311         return nil
1312 }