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