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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "context"
   6         "encoding/binary"
   7         "errors"
   8         "fmt"
   9         "github.com/go-playground/validator/v10"
  10         "go.uber.org/zap"
  11         "golang.org/x/text/encoding/charmap"
  12         "gopkg.in/yaml.v3"
  13         "io"
  14         "io/fs"
  15         "math/big"
  16         "math/rand"
  17         "net"
  18         "os"
  19         "path/filepath"
  20         "strings"
  21         "sync"
  22         "time"
  23 )
  24
  25 type contextKey string
  26
  27 var contextKeyReq = contextKey("req")
  28
  29 type requestCtx struct {
  30         remoteAddr string
  31 }
  32
  33 // Converts bytes from Mac Roman encoding to UTF-8
  34 var txtDecoder = charmap.Macintosh.NewDecoder()
  35
  36 // Converts bytes from UTF-8 to Mac Roman encoding
  37 var txtEncoder = charmap.Macintosh.NewEncoder()
  38
  39 type Server struct {
  40         NetInterface  string
  41         Port          int
  42         Accounts      map[string]*Account
  43         Agreement     []byte
  44         Clients       map[uint16]*ClientConn
  45         fileTransfers map[[4]byte]*FileTransfer
  46
  47         Config    *Config
  48         ConfigDir string
  49         Logger    *zap.SugaredLogger
  50
  51         PrivateChatsMu sync.Mutex
  52         PrivateChats   map[uint32]*PrivateChat
  53
  54         NextGuestID   *uint16
  55         TrackerPassID [4]byte
  56
  57         StatsMu sync.Mutex
  58         Stats   *Stats
  59
  60         FS FileStore // Storage backend to use for File storage
  61
  62         outbox chan Transaction
  63         mux    sync.Mutex
  64
  65         threadedNewsMux sync.Mutex
  66         ThreadedNews    *ThreadedNews
  67
  68         flatNewsMux sync.Mutex
  69         FlatNews    []byte
  70
  71         banListMU sync.Mutex
  72         banList   map[string]*time.Time
  73 }
  74
  75 func (s *Server) CurrentStats() Stats {
  76         s.StatsMu.Lock()
  77         defer s.StatsMu.Unlock()
  78
  79         stats := s.Stats
  80         stats.CurrentlyConnected = len(s.Clients)
  81
  82         return *stats
  83 }
  84
  85 type PrivateChat struct {
  86         Subject    string
  87         ClientConn map[uint16]*ClientConn
  88 }
  89
  90 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  91         s.Logger.Infow("Hotline server started",
  92                 "version", VERSION,
  93                 "API port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port),
  94                 "Transfer port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1),
  95         )
  96
  97         var wg sync.WaitGroup
  98
  99         wg.Add(1)
 100         go func() {
 101                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
 102                 if err != nil {
 103                         s.Logger.Fatal(err)
 104                 }
 105
 106                 s.Logger.Fatal(s.Serve(ctx, ln))
 107         }()
 108
 109         wg.Add(1)
 110         go func() {
 111                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
 112                 if err != nil {
 113                         s.Logger.Fatal(err)
 114                 }
 115
 116                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 117         }()
 118
 119         wg.Wait()
 120
 121         return nil
 122 }
 123
 124 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 125         for {
 126                 conn, err := ln.Accept()
 127                 if err != nil {
 128                         return err
 129                 }
 130
 131                 go func() {
 132                         defer func() { _ = conn.Close() }()
 133
 134                         err = s.handleFileTransfer(
 135                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 136                                         remoteAddr: conn.RemoteAddr().String(),
 137                                 }),
 138                                 conn,
 139                         )
 140
 141                         if err != nil {
 142                                 s.Logger.Errorw("file transfer error", "reason", err)
 143                         }
 144                 }()
 145         }
 146 }
 147
 148 func (s *Server) sendTransaction(t Transaction) error {
 149         clientID, err := byteToInt(*t.clientID)
 150         if err != nil {
 151                 return err
 152         }
 153
 154         s.mux.Lock()
 155         client := s.Clients[uint16(clientID)]
 156         s.mux.Unlock()
 157         if client == nil {
 158                 return fmt.Errorf("invalid client id %v", *t.clientID)
 159         }
 160
 161         b, err := t.MarshalBinary()
 162         if err != nil {
 163                 return err
 164         }
 165
 166         _, err = client.Connection.Write(b)
 167         if err != nil {
 168                 return err
 169         }
 170
 171         return nil
 172 }
 173
 174 func (s *Server) processOutbox() {
 175         for {
 176                 t := <-s.outbox
 177                 go func() {
 178                         if err := s.sendTransaction(t); err != nil {
 179                                 s.Logger.Errorw("error sending transaction", "err", err)
 180                         }
 181                 }()
 182         }
 183 }
 184
 185 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 186         go s.processOutbox()
 187
 188         for {
 189                 conn, err := ln.Accept()
 190                 if err != nil {
 191                         s.Logger.Errorw("error accepting connection", "err", err)
 192                 }
 193                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 194                         remoteAddr: conn.RemoteAddr().String(),
 195                 })
 196
 197                 go func() {
 198                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 199
 200                         defer conn.Close()
 201                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 202                                 if err == io.EOF {
 203                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 204                                 } else {
 205                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 206                                 }
 207                         }
 208                 }()
 209         }
 210 }
 211
 212 const (
 213         agreementFile = "Agreement.txt"
 214 )
 215
 216 // NewServer constructs a new Server from a config dir
 217 func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredLogger, fs FileStore) (*Server, error) {
 218         server := Server{
 219                 NetInterface:  netInterface,
 220                 Port:          netPort,
 221                 Accounts:      make(map[string]*Account),
 222                 Config:        new(Config),
 223                 Clients:       make(map[uint16]*ClientConn),
 224                 fileTransfers: make(map[[4]byte]*FileTransfer),
 225                 PrivateChats:  make(map[uint32]*PrivateChat),
 226                 ConfigDir:     configDir,
 227                 Logger:        logger,
 228                 NextGuestID:   new(uint16),
 229                 outbox:        make(chan Transaction),
 230                 Stats:         &Stats{Since: time.Now()},
 231                 ThreadedNews:  &ThreadedNews{},
 232                 FS:            fs,
 233                 banList:       make(map[string]*time.Time),
 234         }
 235
 236         var err error
 237
 238         // generate a new random passID for tracker registration
 239         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 240                 return nil, err
 241         }
 242
 243         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 244         if err != nil {
 245                 return nil, err
 246         }
 247
 248         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 249                 return nil, err
 250         }
 251
 252         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 253         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 254
 255         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 256                 return nil, err
 257         }
 258
 259         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 260                 return nil, err
 261         }
 262
 263         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 264                 return nil, err
 265         }
 266
 267         // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
 268         if !filepath.IsAbs(server.Config.FileRoot) {
 269                 server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
 270         }
 271
 272         *server.NextGuestID = 1
 273
 274         if server.Config.EnableTrackerRegistration {
 275                 server.Logger.Infow(
 276                         "Tracker registration enabled",
 277                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 278                         "trackers", server.Config.Trackers,
 279                 )
 280
 281                 go func() {
 282                         for {
 283                                 tr := &TrackerRegistration{
 284                                         UserCount:   server.userCount(),
 285                                         PassID:      server.TrackerPassID[:],
 286                                         Name:        server.Config.Name,
 287                                         Description: server.Config.Description,
 288                                 }
 289                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 290                                 for _, t := range server.Config.Trackers {
 291                                         if err := register(t, tr); err != nil {
 292                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 293                                         }
 294                                         server.Logger.Debugw("Sent Tracker registration", "addr", t)
 295                                 }
 296
 297                                 time.Sleep(trackerUpdateFrequency * time.Second)
 298                         }
 299                 }()
 300         }
 301
 302         // Start Client Keepalive go routine
 303         go server.keepaliveHandler()
 304
 305         return &server, nil
 306 }
 307
 308 func (s *Server) userCount() int {
 309         s.mux.Lock()
 310         defer s.mux.Unlock()
 311
 312         return len(s.Clients)
 313 }
 314
 315 func (s *Server) keepaliveHandler() {
 316         for {
 317                 time.Sleep(idleCheckInterval * time.Second)
 318                 s.mux.Lock()
 319
 320                 for _, c := range s.Clients {
 321                         c.IdleTime += idleCheckInterval
 322                         if c.IdleTime > userIdleSeconds && !c.Idle {
 323                                 c.Idle = true
 324
 325                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 326                                 flagBitmap.SetBit(flagBitmap, UserFlagAway, 1)
 327                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 328
 329                                 c.sendAll(
 330                                         TranNotifyChangeUser,
 331                                         NewField(FieldUserID, *c.ID),
 332                                         NewField(FieldUserFlags, c.Flags),
 333                                         NewField(FieldUserName, c.UserName),
 334                                         NewField(FieldUserIconID, c.Icon),
 335                                 )
 336                         }
 337                 }
 338                 s.mux.Unlock()
 339         }
 340 }
 341
 342 func (s *Server) writeBanList() error {
 343         s.banListMU.Lock()
 344         defer s.banListMU.Unlock()
 345
 346         out, err := yaml.Marshal(s.banList)
 347         if err != nil {
 348                 return err
 349         }
 350         err = os.WriteFile(
 351                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 352                 out,
 353                 0666,
 354         )
 355         return err
 356 }
 357
 358 func (s *Server) writeThreadedNews() error {
 359         s.threadedNewsMux.Lock()
 360         defer s.threadedNewsMux.Unlock()
 361
 362         out, err := yaml.Marshal(s.ThreadedNews)
 363         if err != nil {
 364                 return err
 365         }
 366         err = s.FS.WriteFile(
 367                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 368                 out,
 369                 0666,
 370         )
 371         return err
 372 }
 373
 374 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 375         s.mux.Lock()
 376         defer s.mux.Unlock()
 377
 378         clientConn := &ClientConn{
 379                 ID:         &[]byte{0, 0},
 380                 Icon:       []byte{0, 0},
 381                 Flags:      []byte{0, 0},
 382                 UserName:   []byte{},
 383                 Connection: conn,
 384                 Server:     s,
 385                 Version:    []byte{},
 386                 AutoReply:  []byte{},
 387                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 388                 RemoteAddr: remoteAddr,
 389         }
 390         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 391                 FileDownload:   {},
 392                 FileUpload:     {},
 393                 FolderDownload: {},
 394                 FolderUpload:   {},
 395                 bannerDownload: {},
 396         }
 397
 398         *s.NextGuestID++
 399         ID := *s.NextGuestID
 400
 401         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 402         s.Clients[ID] = clientConn
 403
 404         return clientConn
 405 }
 406
 407 // NewUser creates a new user account entry in the server map and config file
 408 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 409         s.mux.Lock()
 410         defer s.mux.Unlock()
 411
 412         account := Account{
 413                 Login:    login,
 414                 Name:     name,
 415                 Password: hashAndSalt([]byte(password)),
 416                 Access:   access,
 417         }
 418         out, err := yaml.Marshal(&account)
 419         if err != nil {
 420                 return err
 421         }
 422         s.Accounts[login] = &account
 423
 424         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 425 }
 426
 427 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 428         s.mux.Lock()
 429         defer s.mux.Unlock()
 430
 431         // update renames the user login
 432         if login != newLogin {
 433                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 434                 if err != nil {
 435                         return err
 436                 }
 437                 s.Accounts[newLogin] = s.Accounts[login]
 438                 delete(s.Accounts, login)
 439         }
 440
 441         account := s.Accounts[newLogin]
 442         account.Access = access
 443         account.Name = name
 444         account.Password = password
 445
 446         out, err := yaml.Marshal(&account)
 447         if err != nil {
 448                 return err
 449         }
 450
 451         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 452                 return err
 453         }
 454
 455         return nil
 456 }
 457
 458 // DeleteUser deletes the user account
 459 func (s *Server) DeleteUser(login string) error {
 460         s.mux.Lock()
 461         defer s.mux.Unlock()
 462
 463         delete(s.Accounts, login)
 464
 465         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 466 }
 467
 468 func (s *Server) connectedUsers() []Field {
 469         s.mux.Lock()
 470         defer s.mux.Unlock()
 471
 472         var connectedUsers []Field
 473         for _, c := range sortedClients(s.Clients) {
 474                 user := User{
 475                         ID:    *c.ID,
 476                         Icon:  c.Icon,
 477                         Flags: c.Flags,
 478                         Name:  string(c.UserName),
 479                 }
 480                 connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, user.Payload()))
 481         }
 482         return connectedUsers
 483 }
 484
 485 func (s *Server) loadBanList(path string) error {
 486         fh, err := os.Open(path)
 487         if err != nil {
 488                 return err
 489         }
 490         decoder := yaml.NewDecoder(fh)
 491
 492         return decoder.Decode(s.banList)
 493 }
 494
 495 // loadThreadedNews loads the threaded news data from disk
 496 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 497         fh, err := os.Open(threadedNewsPath)
 498         if err != nil {
 499                 return err
 500         }
 501         decoder := yaml.NewDecoder(fh)
 502
 503         return decoder.Decode(s.ThreadedNews)
 504 }
 505
 506 // loadAccounts loads account data from disk
 507 func (s *Server) loadAccounts(userDir string) error {
 508         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 509         if err != nil {
 510                 return err
 511         }
 512
 513         if len(matches) == 0 {
 514                 return errors.New("no user accounts found in " + userDir)
 515         }
 516
 517         for _, file := range matches {
 518                 fh, err := s.FS.Open(file)
 519                 if err != nil {
 520                         return err
 521                 }
 522
 523                 account := Account{}
 524                 decoder := yaml.NewDecoder(fh)
 525                 if err := decoder.Decode(&account); err != nil {
 526                         return err
 527                 }
 528
 529                 s.Accounts[account.Login] = &account
 530         }
 531         return nil
 532 }
 533
 534 func (s *Server) loadConfig(path string) error {
 535         fh, err := s.FS.Open(path)
 536         if err != nil {
 537                 return err
 538         }
 539
 540         decoder := yaml.NewDecoder(fh)
 541         err = decoder.Decode(s.Config)
 542         if err != nil {
 543                 return err
 544         }
 545
 546         validate := validator.New()
 547         err = validate.Struct(s.Config)
 548         if err != nil {
 549                 return err
 550         }
 551         return nil
 552 }
 553
 554 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 555 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 556         defer dontPanic(s.Logger)
 557
 558         if err := Handshake(rwc); err != nil {
 559                 return err
 560         }
 561
 562         // Create a new scanner for parsing incoming bytes into transaction tokens
 563         scanner := bufio.NewScanner(rwc)
 564         scanner.Split(transactionScanner)
 565
 566         scanner.Scan()
 567
 568         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 569         // scanner re-uses the buffer for subsequent scans.
 570         buf := make([]byte, len(scanner.Bytes()))
 571         copy(buf, scanner.Bytes())
 572
 573         var clientLogin Transaction
 574         if _, err := clientLogin.Write(buf); err != nil {
 575                 return err
 576         }
 577
 578         // check if remoteAddr is present in the ban list
 579         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 580                 // permaban
 581                 if banUntil == nil {
 582                         t := NewTransaction(
 583                                 TranServerMsg,
 584                                 &[]byte{0, 0},
 585                                 NewField(FieldData, []byte("You are permanently banned on this server")),
 586                                 NewField(FieldChatOptions, []byte{0, 0}),
 587                         )
 588
 589                         b, err := t.MarshalBinary()
 590                         if err != nil {
 591                                 return err
 592                         }
 593
 594                         _, err = rwc.Write(b)
 595                         if err != nil {
 596                                 return err
 597                         }
 598
 599                         time.Sleep(1 * time.Second)
 600                         return nil
 601                 }
 602
 603                 // temporary ban
 604                 if time.Now().Before(*banUntil) {
 605                         t := NewTransaction(
 606                                 TranServerMsg,
 607                                 &[]byte{0, 0},
 608                                 NewField(FieldData, []byte("You are temporarily banned on this server")),
 609                                 NewField(FieldChatOptions, []byte{0, 0}),
 610                         )
 611                         b, err := t.MarshalBinary()
 612                         if err != nil {
 613                                 return err
 614                         }
 615
 616                         _, err = rwc.Write(b)
 617                         if err != nil {
 618                                 return err
 619                         }
 620
 621                         time.Sleep(1 * time.Second)
 622                         return nil
 623                 }
 624         }
 625
 626         c := s.NewClientConn(rwc, remoteAddr)
 627         defer c.Disconnect()
 628
 629         encodedLogin := clientLogin.GetField(FieldUserLogin).Data
 630         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 631         c.Version = clientLogin.GetField(FieldVersion).Data
 632
 633         var login string
 634         for _, char := range encodedLogin {
 635                 login += string(rune(255 - uint(char)))
 636         }
 637         if login == "" {
 638                 login = GuestAccount
 639         }
 640
 641         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 642
 643         // If authentication fails, send error reply and close connection
 644         if !c.Authenticate(login, encodedPassword) {
 645                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 646                 b, err := t.MarshalBinary()
 647                 if err != nil {
 648                         return err
 649                 }
 650                 if _, err := rwc.Write(b); err != nil {
 651                         return err
 652                 }
 653
 654                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 655
 656                 return nil
 657         }
 658
 659         if clientLogin.GetField(FieldUserIconID).Data != nil {
 660                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 661         }
 662
 663         c.Account = c.Server.Accounts[login]
 664
 665         if clientLogin.GetField(FieldUserName).Data != nil {
 666                 if c.Authorize(accessAnyName) {
 667                         c.UserName = clientLogin.GetField(FieldUserName).Data
 668                 } else {
 669                         c.UserName = []byte(c.Account.Name)
 670                 }
 671         }
 672
 673         if c.Authorize(accessDisconUser) {
 674                 c.Flags = []byte{0, 2}
 675         }
 676
 677         s.outbox <- c.NewReply(&clientLogin,
 678                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 679                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 680                 NewField(FieldServerName, []byte(s.Config.Name)),
 681         )
 682
 683         // Send user access privs so client UI knows how to behave
 684         c.Server.outbox <- *NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 685
 686         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 687         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 688         // TranShowAgreement but with the NoServerAgreement field set to 1.
 689         if c.Authorize(accessNoAgreement) {
 690                 // If client version is nil, then the client uses the 1.2.3 login behavior
 691                 if c.Version != nil {
 692                         c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 693                 }
 694         } else {
 695                 c.Server.outbox <- *NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
 696         }
 697
 698         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 699         // flow and not the 1.5+ flow.
 700         if len(c.UserName) != 0 {
 701                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 702                 // part of TranAgreed
 703                 c.logger = c.logger.With("name", string(c.UserName))
 704
 705                 c.logger.Infow("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
 706
 707                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 708                 // information yet, so we do it in TranAgreed instead
 709                 for _, t := range c.notifyOthers(
 710                         *NewTransaction(
 711                                 TranNotifyChangeUser, nil,
 712                                 NewField(FieldUserName, c.UserName),
 713                                 NewField(FieldUserID, *c.ID),
 714                                 NewField(FieldUserIconID, c.Icon),
 715                                 NewField(FieldUserFlags, c.Flags),
 716                         ),
 717                 ) {
 718                         c.Server.outbox <- t
 719                 }
 720         }
 721
 722         c.Server.Stats.ConnectionCounter += 1
 723         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 724                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 725         }
 726
 727         // Scan for new transactions and handle them as they come in.
 728         for scanner.Scan() {
 729                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 730                 // scanner re-uses the buffer for subsequent scans.
 731                 buf := make([]byte, len(scanner.Bytes()))
 732                 copy(buf, scanner.Bytes())
 733
 734                 var t Transaction
 735                 if _, err := t.Write(buf); err != nil {
 736                         return err
 737                 }
 738
 739                 if err := c.handleTransaction(t); err != nil {
 740                         c.logger.Errorw("Error handling transaction", "err", err)
 741                 }
 742         }
 743         return nil
 744 }
 745
 746 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 747         s.PrivateChatsMu.Lock()
 748         defer s.PrivateChatsMu.Unlock()
 749
 750         randID := make([]byte, 4)
 751         rand.Read(randID)
 752         data := binary.BigEndian.Uint32(randID)
 753
 754         s.PrivateChats[data] = &PrivateChat{
 755                 ClientConn: make(map[uint16]*ClientConn),
 756         }
 757         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 758
 759         return randID
 760 }
 761
 762 const dlFldrActionSendFile = 1
 763 const dlFldrActionResumeFile = 2
 764 const dlFldrActionNextFile = 3
 765
 766 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 767 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 768         defer dontPanic(s.Logger)
 769
 770         txBuf := make([]byte, 16)
 771         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 772                 return err
 773         }
 774
 775         var t transfer
 776         if _, err := t.Write(txBuf); err != nil {
 777                 return err
 778         }
 779
 780         defer func() {
 781                 s.mux.Lock()
 782                 delete(s.fileTransfers, t.ReferenceNumber)
 783                 s.mux.Unlock()
 784
 785                 // Wait a few seconds before closing the connection: this is a workaround for problems
 786                 // observed with Windows clients where the client must initiate close of the TCP connection before
 787                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 788                 time.Sleep(3 * time.Second)
 789         }()
 790
 791         s.mux.Lock()
 792         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 793         s.mux.Unlock()
 794         if !ok {
 795                 return errors.New("invalid transaction ID")
 796         }
 797
 798         defer func() {
 799                 fileTransfer.ClientConn.transfersMU.Lock()
 800                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 801                 fileTransfer.ClientConn.transfersMU.Unlock()
 802         }()
 803
 804         rLogger := s.Logger.With(
 805                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 806                 "login", fileTransfer.ClientConn.Account.Login,
 807                 "name", string(fileTransfer.ClientConn.UserName),
 808         )
 809
 810         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 811         if err != nil {
 812                 return err
 813         }
 814
 815         switch fileTransfer.Type {
 816         case bannerDownload:
 817                 if err := s.bannerDownload(rwc); err != nil {
 818                         return err
 819                 }
 820         case FileDownload:
 821                 s.Stats.DownloadCounter += 1
 822                 s.Stats.DownloadsInProgress += 1
 823                 defer func() {
 824                         s.Stats.DownloadsInProgress -= 1
 825                 }()
 826
 827                 var dataOffset int64
 828                 if fileTransfer.fileResumeData != nil {
 829                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 830                 }
 831
 832                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 833                 if err != nil {
 834                         return err
 835                 }
 836
 837                 rLogger.Infow("File download started", "filePath", fullPath)
 838
 839                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 840                 if fileTransfer.options == nil {
 841                         // Start by sending flat file object to client
 842                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 843                                 return err
 844                         }
 845                 }
 846
 847                 file, err := fw.dataForkReader()
 848                 if err != nil {
 849                         return err
 850                 }
 851
 852                 br := bufio.NewReader(file)
 853                 if _, err := br.Discard(int(dataOffset)); err != nil {
 854                         return err
 855                 }
 856
 857                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 858                         return err
 859                 }
 860
 861                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 862                 if fileTransfer.fileResumeData == nil {
 863                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 864                         if err != nil {
 865                                 return err
 866                         }
 867                 }
 868
 869                 rFile, err := fw.rsrcForkFile()
 870                 if err != nil {
 871                         return nil
 872                 }
 873
 874                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 875                         return err
 876                 }
 877
 878         case FileUpload:
 879                 s.Stats.UploadCounter += 1
 880                 s.Stats.UploadsInProgress += 1
 881                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 882
 883                 var file *os.File
 884
 885                 // A file upload has three possible cases:
 886                 // 1) Upload a new file
 887                 // 2) Resume a partially transferred file
 888                 // 3) Replace a fully uploaded file
 889                 //  We have to infer which case applies by inspecting what is already on the filesystem
 890
 891                 // 1) Check for existing file:
 892                 _, err = os.Stat(fullPath)
 893                 if err == nil {
 894                         return errors.New("existing file found at " + fullPath)
 895                 }
 896                 if errors.Is(err, fs.ErrNotExist) {
 897                         // If not found, open or create a new .incomplete file
 898                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 899                         if err != nil {
 900                                 return err
 901                         }
 902                 }
 903
 904                 f, err := newFileWrapper(s.FS, fullPath, 0)
 905                 if err != nil {
 906                         return err
 907                 }
 908
 909                 rLogger.Infow("File upload started", "dstFile", fullPath)
 910
 911                 rForkWriter := io.Discard
 912                 iForkWriter := io.Discard
 913                 if s.Config.PreserveResourceForks {
 914                         rForkWriter, err = f.rsrcForkWriter()
 915                         if err != nil {
 916                                 return err
 917                         }
 918
 919                         iForkWriter, err = f.infoForkWriter()
 920                         if err != nil {
 921                                 return err
 922                         }
 923                 }
 924
 925                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 926                         s.Logger.Error(err)
 927                 }
 928
 929                 if err := file.Close(); err != nil {
 930                         return err
 931                 }
 932
 933                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 934                         return err
 935                 }
 936
 937                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 938
 939         case FolderDownload:
 940                 s.Stats.DownloadCounter += 1
 941                 s.Stats.DownloadsInProgress += 1
 942                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 943
 944                 // Folder Download flow:
 945                 // 1. Get filePath from the transfer
 946                 // 2. Iterate over files
 947                 // 3. For each fileWrapper:
 948                 //       Send fileWrapper header to client
 949                 // The client can reply in 3 ways:
 950                 //
 951                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 952                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 953                 //
 954                 // 2. If download of a fileWrapper is to be resumed:
 955                 //              client sends:
 956                 //                      []byte{0x00, 0x02} // download folder action
 957                 //                      [2]byte // Resume data size
 958                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 959                 //
 960                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 961                 //
 962                 // When download is requested (case 2 or 3), server replies with:
 963                 //                      [4]byte - fileWrapper size
 964                 //                      []byte  - Flattened File Object
 965                 //
 966                 // After every fileWrapper download, client could request next fileWrapper with:
 967                 //                      []byte{0x00, 0x03}
 968                 //
 969                 // This notifies the server to send the next item header
 970
 971                 basePathLen := len(fullPath)
 972
 973                 rLogger.Infow("Start folder download", "path", fullPath)
 974
 975                 nextAction := make([]byte, 2)
 976                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 977                         return err
 978                 }
 979
 980                 i := 0
 981                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 982                         s.Stats.DownloadCounter += 1
 983                         i += 1
 984
 985                         if err != nil {
 986                                 return err
 987                         }
 988
 989                         // skip dot files
 990                         if strings.HasPrefix(info.Name(), ".") {
 991                                 return nil
 992                         }
 993
 994                         hlFile, err := newFileWrapper(s.FS, path, 0)
 995                         if err != nil {
 996                                 return err
 997                         }
 998
 999                         subPath := path[basePathLen+1:]
1000                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
1001
1002                         if i == 1 {
1003                                 return nil
1004                         }
1005
1006                         fileHeader := NewFileHeader(subPath, info.IsDir())
1007
1008                         // Send the fileWrapper header to client
1009                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
1010                                 s.Logger.Errorf("error sending file header: %v", err)
1011                                 return err
1012                         }
1013
1014                         // Read the client's Next Action request
1015                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1016                                 return err
1017                         }
1018
1019                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
1020
1021                         var dataOffset int64
1022
1023                         switch nextAction[1] {
1024                         case dlFldrActionResumeFile:
1025                                 // get size of resumeData
1026                                 resumeDataByteLen := make([]byte, 2)
1027                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
1028                                         return err
1029                                 }
1030
1031                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
1032                                 resumeDataBytes := make([]byte, resumeDataLen)
1033                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
1034                                         return err
1035                                 }
1036
1037                                 var frd FileResumeData
1038                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1039                                         return err
1040                                 }
1041                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1042                         case dlFldrActionNextFile:
1043                                 // client asked to skip this file
1044                                 return nil
1045                         }
1046
1047                         if info.IsDir() {
1048                                 return nil
1049                         }
1050
1051                         rLogger.Infow("File download started",
1052                                 "fileName", info.Name(),
1053                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1054                         )
1055
1056                         // Send file size to client
1057                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1058                                 s.Logger.Error(err)
1059                                 return err
1060                         }
1061
1062                         // Send ffo bytes to client
1063                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1064                                 s.Logger.Error(err)
1065                                 return err
1066                         }
1067
1068                         file, err := s.FS.Open(path)
1069                         if err != nil {
1070                                 return err
1071                         }
1072
1073                         // wr := bufio.NewWriterSize(rwc, 1460)
1074                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1075                                 return err
1076                         }
1077
1078                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1079                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1080                                 if err != nil {
1081                                         return err
1082                                 }
1083
1084                                 rFile, err := hlFile.rsrcForkFile()
1085                                 if err != nil {
1086                                         return err
1087                                 }
1088
1089                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1090                                         return err
1091                                 }
1092                         }
1093
1094                         // Read the client's Next Action request.  This is always 3, I think?
1095                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1096                                 return err
1097                         }
1098
1099                         return nil
1100                 })
1101
1102                 if err != nil {
1103                         return err
1104                 }
1105
1106         case FolderUpload:
1107                 s.Stats.UploadCounter += 1
1108                 s.Stats.UploadsInProgress += 1
1109                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1110                 rLogger.Infow(
1111                         "Folder upload started",
1112                         "dstPath", fullPath,
1113                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1114                         "FolderItemCount", fileTransfer.FolderItemCount,
1115                 )
1116
1117                 // Check if the target folder exists.  If not, create it.
1118                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1119                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1120                                 return err
1121                         }
1122                 }
1123
1124                 // Begin the folder upload flow by sending the "next file action" to client
1125                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1126                         return err
1127                 }
1128
1129                 fileSize := make([]byte, 4)
1130
1131                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1132                         s.Stats.UploadCounter += 1
1133
1134                         var fu folderUpload
1135                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1136                                 return err
1137                         }
1138                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1139                                 return err
1140                         }
1141                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1142                                 return err
1143                         }
1144
1145                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1146
1147                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1148                                 return err
1149                         }
1150
1151                         rLogger.Infow(
1152                                 "Folder upload continued",
1153                                 "FormattedPath", fu.FormattedPath(),
1154                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1155                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1156                         )
1157
1158                         if fu.IsFolder == [2]byte{0, 1} {
1159                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1160                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1161                                                 return err
1162                                         }
1163                                 }
1164
1165                                 // Tell client to send next file
1166                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1167                                         return err
1168                                 }
1169                         } else {
1170                                 nextAction := dlFldrActionSendFile
1171
1172                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1173                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1174                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1175                                         return err
1176                                 }
1177                                 if err == nil {
1178                                         nextAction = dlFldrActionNextFile
1179                                 }
1180
1181                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1182                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1183                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1184                                         return err
1185                                 }
1186                                 if err == nil {
1187                                         nextAction = dlFldrActionResumeFile
1188                                 }
1189
1190                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1191                                         return err
1192                                 }
1193
1194                                 switch nextAction {
1195                                 case dlFldrActionNextFile:
1196                                         continue
1197                                 case dlFldrActionResumeFile:
1198                                         offset := make([]byte, 4)
1199                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1200
1201                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1202                                         if err != nil {
1203                                                 return err
1204                                         }
1205
1206                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1207
1208                                         b, _ := fileResumeData.BinaryMarshal()
1209
1210                                         bs := make([]byte, 2)
1211                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1212
1213                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1214                                                 return err
1215                                         }
1216
1217                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1218                                                 return err
1219                                         }
1220
1221                                         if err := receiveFile(rwc, file, io.Discard, io.Discard, fileTransfer.bytesSentCounter); err != nil {
1222                                                 s.Logger.Error(err)
1223                                         }
1224
1225                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1226                                         if err != nil {
1227                                                 return err
1228                                         }
1229
1230                                 case dlFldrActionSendFile:
1231                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1232                                                 return err
1233                                         }
1234
1235                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1236
1237                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1238                                         if err != nil {
1239                                                 return err
1240                                         }
1241
1242                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1243
1244                                         incWriter, err := hlFile.incFileWriter()
1245                                         if err != nil {
1246                                                 return err
1247                                         }
1248
1249                                         rForkWriter := io.Discard
1250                                         iForkWriter := io.Discard
1251                                         if s.Config.PreserveResourceForks {
1252                                                 iForkWriter, err = hlFile.infoForkWriter()
1253                                                 if err != nil {
1254                                                         return err
1255                                                 }
1256
1257                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1258                                                 if err != nil {
1259                                                         return err
1260                                                 }
1261                                         }
1262                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1263                                                 return err
1264                                         }
1265
1266                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1267                                                 return err
1268                                         }
1269                                 }
1270
1271                                 // Tell client to send next fileWrapper
1272                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1273                                         return err
1274                                 }
1275                         }
1276                 }
1277                 rLogger.Infof("Folder upload complete")
1278         }
1279
1280         return nil
1281 }