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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "bytes"
   6         "context"
   7         "encoding/binary"
   8         "errors"
   9         "fmt"
  10         "github.com/go-playground/validator/v10"
  11         "go.uber.org/zap"
  12         "gopkg.in/yaml.v3"
  13         "io"
  14         "io/fs"
  15         "io/ioutil"
  16         "math/big"
  17         "math/rand"
  18         "net"
  19         "os"
  20         "path/filepath"
  21         "runtime/debug"
  22         "strings"
  23         "sync"
  24         "time"
  25 )
  26
  27 type contextKey string
  28
  29 var contextKeyReq = contextKey("req")
  30
  31 type requestCtx struct {
  32         remoteAddr string
  33         login      string
  34         name       string
  35 }
  36
  37 const (
  38         userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
  39         idleCheckInterval      = 10  // time in seconds to check for idle users
  40         trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
  41 )
  42
  43 var nostalgiaVersion = []byte{0, 0, 2, 0x2c} // version ID used by the Nostalgia client
  44
  45 type Server struct {
  46         Port         int
  47         Accounts     map[string]*Account
  48         Agreement    []byte
  49         Clients      map[uint16]*ClientConn
  50         ThreadedNews *ThreadedNews
  51
  52         fileTransfers map[[4]byte]*FileTransfer
  53
  54         Config        *Config
  55         ConfigDir     string
  56         Logger        *zap.SugaredLogger
  57         PrivateChats  map[uint32]*PrivateChat
  58         NextGuestID   *uint16
  59         TrackerPassID [4]byte
  60         Stats         *Stats
  61
  62         FS FileStore // Storage backend to use for File storage
  63
  64         outbox chan Transaction
  65         mux    sync.Mutex
  66
  67         flatNewsMux sync.Mutex
  68         FlatNews    []byte
  69
  70         banListMU sync.Mutex
  71         banList   map[string]*time.Time
  72 }
  73
  74 type PrivateChat struct {
  75         Subject    string
  76         ClientConn map[uint16]*ClientConn
  77 }
  78
  79 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  80         s.Logger.Infow("Hotline server started",
  81                 "version", VERSION,
  82                 "API port", fmt.Sprintf(":%v", s.Port),
  83                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  84         )
  85
  86         var wg sync.WaitGroup
  87
  88         wg.Add(1)
  89         go func() {
  90                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
  91                 if err != nil {
  92                         s.Logger.Fatal(err)
  93                 }
  94
  95                 s.Logger.Fatal(s.Serve(ctx, ln))
  96         }()
  97
  98         wg.Add(1)
  99         go func() {
 100                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
 101                 if err != nil {
 102                         s.Logger.Fatal(err)
 103
 104                 }
 105
 106                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 107         }()
 108
 109         wg.Wait()
 110
 111         return nil
 112 }
 113
 114 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 115         for {
 116                 conn, err := ln.Accept()
 117                 if err != nil {
 118                         return err
 119                 }
 120
 121                 go func() {
 122                         defer func() { _ = conn.Close() }()
 123
 124                         err = s.handleFileTransfer(
 125                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 126                                         remoteAddr: conn.RemoteAddr().String(),
 127                                 }),
 128                                 conn,
 129                         )
 130
 131                         if err != nil {
 132                                 s.Logger.Errorw("file transfer error", "reason", err)
 133                         }
 134                 }()
 135         }
 136 }
 137
 138 func (s *Server) sendTransaction(t Transaction) error {
 139         clientID, err := byteToInt(*t.clientID)
 140         if err != nil {
 141                 return err
 142         }
 143
 144         s.mux.Lock()
 145         client := s.Clients[uint16(clientID)]
 146         if client == nil {
 147                 return fmt.Errorf("invalid client id %v", *t.clientID)
 148         }
 149
 150         s.mux.Unlock()
 151
 152         b, err := t.MarshalBinary()
 153         if err != nil {
 154                 return err
 155         }
 156
 157         if _, err := client.Connection.Write(b); err != nil {
 158                 return err
 159         }
 160
 161         return nil
 162 }
 163
 164 func (s *Server) processOutbox() {
 165         for {
 166                 t := <-s.outbox
 167                 go func() {
 168                         if err := s.sendTransaction(t); err != nil {
 169                                 s.Logger.Errorw("error sending transaction", "err", err)
 170                         }
 171                 }()
 172         }
 173 }
 174
 175 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 176         go s.processOutbox()
 177
 178         for {
 179                 conn, err := ln.Accept()
 180                 if err != nil {
 181                         s.Logger.Errorw("error accepting connection", "err", err)
 182                 }
 183                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 184                         remoteAddr: conn.RemoteAddr().String(),
 185                 })
 186
 187                 go func() {
 188                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 189
 190                         defer conn.Close()
 191                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 192                                 if err == io.EOF {
 193                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 194                                 } else {
 195                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 196                                 }
 197                         }
 198                 }()
 199         }
 200 }
 201
 202 const (
 203         agreementFile = "Agreement.txt"
 204 )
 205
 206 // NewServer constructs a new Server from a config dir
 207 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 208         server := Server{
 209                 Port:          netPort,
 210                 Accounts:      make(map[string]*Account),
 211                 Config:        new(Config),
 212                 Clients:       make(map[uint16]*ClientConn),
 213                 fileTransfers: make(map[[4]byte]*FileTransfer),
 214                 PrivateChats:  make(map[uint32]*PrivateChat),
 215                 ConfigDir:     configDir,
 216                 Logger:        logger,
 217                 NextGuestID:   new(uint16),
 218                 outbox:        make(chan Transaction),
 219                 Stats:         &Stats{StartTime: time.Now()},
 220                 ThreadedNews:  &ThreadedNews{},
 221                 FS:            FS,
 222                 banList:       make(map[string]*time.Time),
 223         }
 224
 225         var err error
 226
 227         // generate a new random passID for tracker registration
 228         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 229                 return nil, err
 230         }
 231
 232         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 233         if err != nil {
 234                 return nil, err
 235         }
 236
 237         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 238                 return nil, err
 239         }
 240
 241         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 242         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 243
 244         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 245                 return nil, err
 246         }
 247
 248         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 249                 return nil, err
 250         }
 251
 252         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 253                 return nil, err
 254         }
 255
 256         server.Config.FileRoot = filepath.Join(configDir, "Files")
 257
 258         *server.NextGuestID = 1
 259
 260         if server.Config.EnableTrackerRegistration {
 261                 server.Logger.Infow(
 262                         "Tracker registration enabled",
 263                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 264                         "trackers", server.Config.Trackers,
 265                 )
 266
 267                 go func() {
 268                         for {
 269                                 tr := &TrackerRegistration{
 270                                         UserCount:   server.userCount(),
 271                                         PassID:      server.TrackerPassID[:],
 272                                         Name:        server.Config.Name,
 273                                         Description: server.Config.Description,
 274                                 }
 275                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 276                                 for _, t := range server.Config.Trackers {
 277                                         if err := register(t, tr); err != nil {
 278                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 279                                         }
 280                                         server.Logger.Infow("Sent Tracker registration", "data", tr)
 281                                 }
 282
 283                                 time.Sleep(trackerUpdateFrequency * time.Second)
 284                         }
 285                 }()
 286         }
 287
 288         // Start Client Keepalive go routine
 289         go server.keepaliveHandler()
 290
 291         return &server, nil
 292 }
 293
 294 func (s *Server) userCount() int {
 295         s.mux.Lock()
 296         defer s.mux.Unlock()
 297
 298         return len(s.Clients)
 299 }
 300
 301 func (s *Server) keepaliveHandler() {
 302         for {
 303                 time.Sleep(idleCheckInterval * time.Second)
 304                 s.mux.Lock()
 305
 306                 for _, c := range s.Clients {
 307                         c.IdleTime += idleCheckInterval
 308                         if c.IdleTime > userIdleSeconds && !c.Idle {
 309                                 c.Idle = true
 310
 311                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
 312                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 313                                 binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
 314
 315                                 c.sendAll(
 316                                         tranNotifyChangeUser,
 317                                         NewField(fieldUserID, *c.ID),
 318                                         NewField(fieldUserFlags, *c.Flags),
 319                                         NewField(fieldUserName, c.UserName),
 320                                         NewField(fieldUserIconID, *c.Icon),
 321                                 )
 322                         }
 323                 }
 324                 s.mux.Unlock()
 325         }
 326 }
 327
 328 func (s *Server) writeBanList() error {
 329         s.banListMU.Lock()
 330         defer s.banListMU.Unlock()
 331
 332         out, err := yaml.Marshal(s.banList)
 333         if err != nil {
 334                 return err
 335         }
 336         err = ioutil.WriteFile(
 337                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 338                 out,
 339                 0666,
 340         )
 341         return err
 342 }
 343
 344 func (s *Server) writeThreadedNews() error {
 345         s.mux.Lock()
 346         defer s.mux.Unlock()
 347
 348         out, err := yaml.Marshal(s.ThreadedNews)
 349         if err != nil {
 350                 return err
 351         }
 352         err = ioutil.WriteFile(
 353                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 354                 out,
 355                 0666,
 356         )
 357         return err
 358 }
 359
 360 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 361         s.mux.Lock()
 362         defer s.mux.Unlock()
 363
 364         clientConn := &ClientConn{
 365                 ID:         &[]byte{0, 0},
 366                 Icon:       &[]byte{0, 0},
 367                 Flags:      &[]byte{0, 0},
 368                 UserName:   []byte{},
 369                 Connection: conn,
 370                 Server:     s,
 371                 Version:    &[]byte{},
 372                 AutoReply:  []byte{},
 373                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 374                 Agreed:     false,
 375                 RemoteAddr: remoteAddr,
 376         }
 377         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 378                 FileDownload:   {},
 379                 FileUpload:     {},
 380                 FolderDownload: {},
 381                 FolderUpload:   {},
 382                 bannerDownload: {},
 383         }
 384
 385         *s.NextGuestID++
 386         ID := *s.NextGuestID
 387
 388         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 389         s.Clients[ID] = clientConn
 390
 391         return clientConn
 392 }
 393
 394 // NewUser creates a new user account entry in the server map and config file
 395 func (s *Server) NewUser(login, name, password string, access []byte) error {
 396         s.mux.Lock()
 397         defer s.mux.Unlock()
 398
 399         account := Account{
 400                 Login:    login,
 401                 Name:     name,
 402                 Password: hashAndSalt([]byte(password)),
 403                 Access:   &access,
 404         }
 405         out, err := yaml.Marshal(&account)
 406         if err != nil {
 407                 return err
 408         }
 409         s.Accounts[login] = &account
 410
 411         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 412 }
 413
 414 func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
 415         s.mux.Lock()
 416         defer s.mux.Unlock()
 417
 418         // update renames the user login
 419         if login != newLogin {
 420                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 421                 if err != nil {
 422                         return err
 423                 }
 424                 s.Accounts[newLogin] = s.Accounts[login]
 425                 delete(s.Accounts, login)
 426         }
 427
 428         account := s.Accounts[newLogin]
 429         account.Access = &access
 430         account.Name = name
 431         account.Password = password
 432
 433         out, err := yaml.Marshal(&account)
 434         if err != nil {
 435                 return err
 436         }
 437
 438         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 439                 return err
 440         }
 441
 442         return nil
 443 }
 444
 445 // DeleteUser deletes the user account
 446 func (s *Server) DeleteUser(login string) error {
 447         s.mux.Lock()
 448         defer s.mux.Unlock()
 449
 450         delete(s.Accounts, login)
 451
 452         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 453 }
 454
 455 func (s *Server) connectedUsers() []Field {
 456         s.mux.Lock()
 457         defer s.mux.Unlock()
 458
 459         var connectedUsers []Field
 460         for _, c := range sortedClients(s.Clients) {
 461                 if !c.Agreed {
 462                         continue
 463                 }
 464                 user := User{
 465                         ID:    *c.ID,
 466                         Icon:  *c.Icon,
 467                         Flags: *c.Flags,
 468                         Name:  string(c.UserName),
 469                 }
 470                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 471         }
 472         return connectedUsers
 473 }
 474
 475 func (s *Server) loadBanList(path string) error {
 476         fh, err := os.Open(path)
 477         if err != nil {
 478                 return err
 479         }
 480         decoder := yaml.NewDecoder(fh)
 481
 482         return decoder.Decode(s.banList)
 483 }
 484
 485 // loadThreadedNews loads the threaded news data from disk
 486 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 487         fh, err := os.Open(threadedNewsPath)
 488         if err != nil {
 489                 return err
 490         }
 491         decoder := yaml.NewDecoder(fh)
 492
 493         return decoder.Decode(s.ThreadedNews)
 494 }
 495
 496 // loadAccounts loads account data from disk
 497 func (s *Server) loadAccounts(userDir string) error {
 498         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 499         if err != nil {
 500                 return err
 501         }
 502
 503         if len(matches) == 0 {
 504                 return errors.New("no user accounts found in " + userDir)
 505         }
 506
 507         for _, file := range matches {
 508                 fh, err := s.FS.Open(file)
 509                 if err != nil {
 510                         return err
 511                 }
 512
 513                 account := Account{}
 514                 decoder := yaml.NewDecoder(fh)
 515                 if err := decoder.Decode(&account); err != nil {
 516                         return err
 517                 }
 518
 519                 s.Accounts[account.Login] = &account
 520         }
 521         return nil
 522 }
 523
 524 func (s *Server) loadConfig(path string) error {
 525         fh, err := s.FS.Open(path)
 526         if err != nil {
 527                 return err
 528         }
 529
 530         decoder := yaml.NewDecoder(fh)
 531         err = decoder.Decode(s.Config)
 532         if err != nil {
 533                 return err
 534         }
 535
 536         validate := validator.New()
 537         err = validate.Struct(s.Config)
 538         if err != nil {
 539                 return err
 540         }
 541         return nil
 542 }
 543
 544 // dontPanic logs panics instead of crashing
 545 func dontPanic(logger *zap.SugaredLogger) {
 546         if r := recover(); r != nil {
 547                 fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 548                 logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 549         }
 550 }
 551
 552 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 553 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 554         defer dontPanic(s.Logger)
 555
 556         if err := Handshake(rwc); err != nil {
 557                 return err
 558         }
 559
 560         // Create a new scanner for parsing incoming bytes into transaction tokens
 561         scanner := bufio.NewScanner(rwc)
 562         scanner.Split(transactionScanner)
 563
 564         scanner.Scan()
 565
 566         clientLogin, _, err := ReadTransaction(scanner.Bytes())
 567         if err != nil {
 568                 panic(err)
 569         }
 570
 571         c := s.NewClientConn(rwc, remoteAddr)
 572
 573         // check if remoteAddr is present in the ban list
 574         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 575                 // permaban
 576                 if banUntil == nil {
 577                         s.outbox <- *NewTransaction(
 578                                 tranServerMsg,
 579                                 c.ID,
 580                                 NewField(fieldData, []byte("You are permanently banned on this server")),
 581                                 NewField(fieldChatOptions, []byte{0, 0}),
 582                         )
 583                         time.Sleep(1 * time.Second)
 584                         return nil
 585                 } else if time.Now().Before(*banUntil) {
 586                         s.outbox <- *NewTransaction(
 587                                 tranServerMsg,
 588                                 c.ID,
 589                                 NewField(fieldData, []byte("You are temporarily banned on this server")),
 590                                 NewField(fieldChatOptions, []byte{0, 0}),
 591                         )
 592                         time.Sleep(1 * time.Second)
 593                         return nil
 594                 }
 595
 596         }
 597         defer c.Disconnect()
 598
 599         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 600         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 601         *c.Version = clientLogin.GetField(fieldVersion).Data
 602
 603         var login string
 604         for _, char := range encodedLogin {
 605                 login += string(rune(255 - uint(char)))
 606         }
 607         if login == "" {
 608                 login = GuestAccount
 609         }
 610
 611         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 612
 613         // If authentication fails, send error reply and close connection
 614         if !c.Authenticate(login, encodedPassword) {
 615                 t := c.NewErrReply(clientLogin, "Incorrect login.")
 616                 b, err := t.MarshalBinary()
 617                 if err != nil {
 618                         return err
 619                 }
 620                 if _, err := rwc.Write(b); err != nil {
 621                         return err
 622                 }
 623
 624                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", *c.Version))
 625
 626                 return nil
 627         }
 628
 629         if clientLogin.GetField(fieldUserIconID).Data != nil {
 630                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 631         }
 632
 633         c.Account = c.Server.Accounts[login]
 634
 635         if clientLogin.GetField(fieldUserName).Data != nil {
 636                 if c.Authorize(accessAnyName) {
 637                         c.UserName = clientLogin.GetField(fieldUserName).Data
 638                 } else {
 639                         c.UserName = []byte(c.Account.Name)
 640                 }
 641         }
 642
 643         if c.Authorize(accessDisconUser) {
 644                 *c.Flags = []byte{0, 2}
 645         }
 646
 647         s.outbox <- c.NewReply(clientLogin,
 648                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 649                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 650                 NewField(fieldServerName, []byte(s.Config.Name)),
 651         )
 652
 653         // Send user access privs so client UI knows how to behave
 654         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 655
 656         // Show agreement to client
 657         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 658
 659         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 660         if *c.Version == nil || bytes.Equal(*c.Version, nostalgiaVersion) {
 661                 c.Agreed = true
 662                 c.logger = c.logger.With("name", string(c.UserName))
 663                 c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%x", *c.Version))
 664
 665                 for _, t := range c.notifyOthers(
 666                         *NewTransaction(
 667                                 tranNotifyChangeUser, nil,
 668                                 NewField(fieldUserName, c.UserName),
 669                                 NewField(fieldUserID, *c.ID),
 670                                 NewField(fieldUserIconID, *c.Icon),
 671                                 NewField(fieldUserFlags, *c.Flags),
 672                         ),
 673                 ) {
 674                         c.Server.outbox <- t
 675                 }
 676         }
 677
 678         c.Server.Stats.LoginCount += 1
 679
 680         // Scan for new transactions and handle them as they come in.
 681         for scanner.Scan() {
 682                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 683                 // scanner re-uses the buffer for subsequent scans.
 684                 buf := make([]byte, len(scanner.Bytes()))
 685                 copy(buf, scanner.Bytes())
 686
 687                 t, _, err := ReadTransaction(buf)
 688                 if err != nil {
 689                         panic(err)
 690                 }
 691                 if err := c.handleTransaction(*t); err != nil {
 692                         c.logger.Errorw("Error handling transaction", "err", err)
 693                 }
 694         }
 695         return nil
 696 }
 697
 698 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 699         s.mux.Lock()
 700         defer s.mux.Unlock()
 701
 702         randID := make([]byte, 4)
 703         rand.Read(randID)
 704         data := binary.BigEndian.Uint32(randID[:])
 705
 706         s.PrivateChats[data] = &PrivateChat{
 707                 Subject:    "",
 708                 ClientConn: make(map[uint16]*ClientConn),
 709         }
 710         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 711
 712         return randID
 713 }
 714
 715 const dlFldrActionSendFile = 1
 716 const dlFldrActionResumeFile = 2
 717 const dlFldrActionNextFile = 3
 718
 719 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 720 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 721         defer dontPanic(s.Logger)
 722
 723         txBuf := make([]byte, 16)
 724         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 725                 return err
 726         }
 727
 728         var t transfer
 729         if _, err := t.Write(txBuf); err != nil {
 730                 return err
 731         }
 732
 733         defer func() {
 734                 s.mux.Lock()
 735                 delete(s.fileTransfers, t.ReferenceNumber)
 736                 s.mux.Unlock()
 737
 738         }()
 739
 740         s.mux.Lock()
 741         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 742         s.mux.Unlock()
 743         if !ok {
 744                 return errors.New("invalid transaction ID")
 745         }
 746
 747         defer func() {
 748                 fileTransfer.ClientConn.transfersMU.Lock()
 749                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 750                 fileTransfer.ClientConn.transfersMU.Unlock()
 751         }()
 752
 753         rLogger := s.Logger.With(
 754                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 755                 "login", fileTransfer.ClientConn.Account.Login,
 756                 "name", string(fileTransfer.ClientConn.UserName),
 757         )
 758
 759         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 760         if err != nil {
 761                 return err
 762         }
 763
 764         switch fileTransfer.Type {
 765         case bannerDownload:
 766                 if err := s.bannerDownload(rwc); err != nil {
 767                         panic(err)
 768                         return err
 769                 }
 770         case FileDownload:
 771                 s.Stats.DownloadCounter += 1
 772
 773                 var dataOffset int64
 774                 if fileTransfer.fileResumeData != nil {
 775                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 776                 }
 777
 778                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 779                 if err != nil {
 780                         return err
 781                 }
 782
 783                 rLogger.Infow("File download started", "filePath", fullPath)
 784
 785                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 786                 if fileTransfer.options == nil {
 787                         // Start by sending flat file object to client
 788                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 789                                 return err
 790                         }
 791                 }
 792
 793                 file, err := fw.dataForkReader()
 794                 if err != nil {
 795                         return err
 796                 }
 797
 798                 br := bufio.NewReader(file)
 799                 if _, err := br.Discard(int(dataOffset)); err != nil {
 800                         return err
 801                 }
 802
 803                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 804                         return err
 805                 }
 806
 807                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 808                 if fileTransfer.fileResumeData == nil {
 809                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 810                         if err != nil {
 811                                 return err
 812                         }
 813                 }
 814
 815                 rFile, err := fw.rsrcForkFile()
 816                 if err != nil {
 817                         return nil
 818                 }
 819
 820                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 821                         return err
 822                 }
 823
 824         case FileUpload:
 825                 s.Stats.UploadCounter += 1
 826
 827                 var file *os.File
 828
 829                 // A file upload has three possible cases:
 830                 // 1) Upload a new file
 831                 // 2) Resume a partially transferred file
 832                 // 3) Replace a fully uploaded file
 833                 //  We have to infer which case applies by inspecting what is already on the filesystem
 834
 835                 // 1) Check for existing file:
 836                 _, err = os.Stat(fullPath)
 837                 if err == nil {
 838                         return errors.New("existing file found at " + fullPath)
 839                 }
 840                 if errors.Is(err, fs.ErrNotExist) {
 841                         // If not found, open or create a new .incomplete file
 842                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 843                         if err != nil {
 844                                 return err
 845                         }
 846                 }
 847
 848                 f, err := newFileWrapper(s.FS, fullPath, 0)
 849                 if err != nil {
 850                         return err
 851                 }
 852
 853                 rLogger.Infow("File upload started", "dstFile", fullPath)
 854
 855                 rForkWriter := io.Discard
 856                 iForkWriter := io.Discard
 857                 if s.Config.PreserveResourceForks {
 858                         rForkWriter, err = f.rsrcForkWriter()
 859                         if err != nil {
 860                                 return err
 861                         }
 862
 863                         iForkWriter, err = f.infoForkWriter()
 864                         if err != nil {
 865                                 return err
 866                         }
 867                 }
 868
 869                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 870                         s.Logger.Error(err)
 871                 }
 872
 873                 if err := file.Close(); err != nil {
 874                         return err
 875                 }
 876
 877                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 878                         return err
 879                 }
 880
 881                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 882         case FolderDownload:
 883                 // Folder Download flow:
 884                 // 1. Get filePath from the transfer
 885                 // 2. Iterate over files
 886                 // 3. For each fileWrapper:
 887                 //       Send fileWrapper header to client
 888                 // The client can reply in 3 ways:
 889                 //
 890                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 891                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 892                 //
 893                 // 2. If download of a fileWrapper is to be resumed:
 894                 //              client sends:
 895                 //                      []byte{0x00, 0x02} // download folder action
 896                 //                      [2]byte // Resume data size
 897                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 898                 //
 899                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 900                 //
 901                 // When download is requested (case 2 or 3), server replies with:
 902                 //                      [4]byte - fileWrapper size
 903                 //                      []byte  - Flattened File Object
 904                 //
 905                 // After every fileWrapper download, client could request next fileWrapper with:
 906                 //                      []byte{0x00, 0x03}
 907                 //
 908                 // This notifies the server to send the next item header
 909
 910                 basePathLen := len(fullPath)
 911
 912                 rLogger.Infow("Start folder download", "path", fullPath)
 913
 914                 nextAction := make([]byte, 2)
 915                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 916                         return err
 917                 }
 918
 919                 i := 0
 920                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 921                         s.Stats.DownloadCounter += 1
 922                         i += 1
 923
 924                         if err != nil {
 925                                 return err
 926                         }
 927
 928                         // skip dot files
 929                         if strings.HasPrefix(info.Name(), ".") {
 930                                 return nil
 931                         }
 932
 933                         hlFile, err := newFileWrapper(s.FS, path, 0)
 934                         if err != nil {
 935                                 return err
 936                         }
 937
 938                         subPath := path[basePathLen+1:]
 939                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 940
 941                         if i == 1 {
 942                                 return nil
 943                         }
 944
 945                         fileHeader := NewFileHeader(subPath, info.IsDir())
 946
 947                         // Send the fileWrapper header to client
 948                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 949                                 s.Logger.Errorf("error sending file header: %v", err)
 950                                 return err
 951                         }
 952
 953                         // Read the client's Next Action request
 954                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 955                                 return err
 956                         }
 957
 958                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 959
 960                         var dataOffset int64
 961
 962                         switch nextAction[1] {
 963                         case dlFldrActionResumeFile:
 964                                 // get size of resumeData
 965                                 resumeDataByteLen := make([]byte, 2)
 966                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 967                                         return err
 968                                 }
 969
 970                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 971                                 resumeDataBytes := make([]byte, resumeDataLen)
 972                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 973                                         return err
 974                                 }
 975
 976                                 var frd FileResumeData
 977                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 978                                         return err
 979                                 }
 980                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 981                         case dlFldrActionNextFile:
 982                                 // client asked to skip this file
 983                                 return nil
 984                         }
 985
 986                         if info.IsDir() {
 987                                 return nil
 988                         }
 989
 990                         rLogger.Infow("File download started",
 991                                 "fileName", info.Name(),
 992                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
 993                         )
 994
 995                         // Send file size to client
 996                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
 997                                 s.Logger.Error(err)
 998                                 return err
 999                         }
1000
1001                         // Send ffo bytes to client
1002                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1003                                 s.Logger.Error(err)
1004                                 return err
1005                         }
1006
1007                         file, err := s.FS.Open(path)
1008                         if err != nil {
1009                                 return err
1010                         }
1011
1012                         // wr := bufio.NewWriterSize(rwc, 1460)
1013                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1014                                 return err
1015                         }
1016
1017                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1018                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1019                                 if err != nil {
1020                                         return err
1021                                 }
1022
1023                                 rFile, err := hlFile.rsrcForkFile()
1024                                 if err != nil {
1025                                         return err
1026                                 }
1027
1028                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1029                                         return err
1030                                 }
1031                         }
1032
1033                         // Read the client's Next Action request.  This is always 3, I think?
1034                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1035                                 return err
1036                         }
1037
1038                         return nil
1039                 })
1040
1041                 if err != nil {
1042                         return err
1043                 }
1044
1045         case FolderUpload:
1046                 rLogger.Infow(
1047                         "Folder upload started",
1048                         "dstPath", fullPath,
1049                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1050                         "FolderItemCount", fileTransfer.FolderItemCount,
1051                 )
1052
1053                 // Check if the target folder exists.  If not, create it.
1054                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1055                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1056                                 return err
1057                         }
1058                 }
1059
1060                 // Begin the folder upload flow by sending the "next file action" to client
1061                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1062                         return err
1063                 }
1064
1065                 fileSize := make([]byte, 4)
1066
1067                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1068                         s.Stats.UploadCounter += 1
1069
1070                         var fu folderUpload
1071                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1072                                 return err
1073                         }
1074                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1075                                 return err
1076                         }
1077                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1078                                 return err
1079                         }
1080
1081                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1082
1083                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1084                                 return err
1085                         }
1086
1087                         rLogger.Infow(
1088                                 "Folder upload continued",
1089                                 "FormattedPath", fu.FormattedPath(),
1090                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1091                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1092                         )
1093
1094                         if fu.IsFolder == [2]byte{0, 1} {
1095                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1096                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1097                                                 return err
1098                                         }
1099                                 }
1100
1101                                 // Tell client to send next file
1102                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1103                                         return err
1104                                 }
1105                         } else {
1106                                 nextAction := dlFldrActionSendFile
1107
1108                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1109                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1110                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1111                                         return err
1112                                 }
1113                                 if err == nil {
1114                                         nextAction = dlFldrActionNextFile
1115                                 }
1116
1117                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1118                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1119                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1120                                         return err
1121                                 }
1122                                 if err == nil {
1123                                         nextAction = dlFldrActionResumeFile
1124                                 }
1125
1126                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1127                                         return err
1128                                 }
1129
1130                                 switch nextAction {
1131                                 case dlFldrActionNextFile:
1132                                         continue
1133                                 case dlFldrActionResumeFile:
1134                                         offset := make([]byte, 4)
1135                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1136
1137                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1138                                         if err != nil {
1139                                                 return err
1140                                         }
1141
1142                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1143
1144                                         b, _ := fileResumeData.BinaryMarshal()
1145
1146                                         bs := make([]byte, 2)
1147                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1148
1149                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1150                                                 return err
1151                                         }
1152
1153                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1154                                                 return err
1155                                         }
1156
1157                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1158                                                 s.Logger.Error(err)
1159                                         }
1160
1161                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1162                                         if err != nil {
1163                                                 return err
1164                                         }
1165
1166                                 case dlFldrActionSendFile:
1167                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1168                                                 return err
1169                                         }
1170
1171                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1172
1173                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1174                                         if err != nil {
1175                                                 return err
1176                                         }
1177
1178                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1179
1180                                         incWriter, err := hlFile.incFileWriter()
1181                                         if err != nil {
1182                                                 return err
1183                                         }
1184
1185                                         rForkWriter := io.Discard
1186                                         iForkWriter := io.Discard
1187                                         if s.Config.PreserveResourceForks {
1188                                                 iForkWriter, err = hlFile.infoForkWriter()
1189                                                 if err != nil {
1190                                                         return err
1191                                                 }
1192
1193                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1194                                                 if err != nil {
1195                                                         return err
1196                                                 }
1197                                         }
1198                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1199                                                 return err
1200                                         }
1201
1202                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1203                                                 return err
1204                                         }
1205                                 }
1206
1207                                 // Tell client to send next fileWrapper
1208                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1209                                         return err
1210                                 }
1211                         }
1212                 }
1213                 rLogger.Infof("Folder upload complete")
1214         }
1215
1216         return nil
1217 }