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         FileTransfers map[uint32]*FileTransfer
  52         Config        *Config
  53         ConfigDir     string
  54         Logger        *zap.SugaredLogger
  55         PrivateChats  map[uint32]*PrivateChat
  56         NextGuestID   *uint16
  57         TrackerPassID [4]byte
  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         flatNewsMux sync.Mutex
  66         FlatNews    []byte
  67 }
  68
  69 type PrivateChat struct {
  70         Subject    string
  71         ClientConn map[uint16]*ClientConn
  72 }
  73
  74 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  75         s.Logger.Infow("Hotline server started",
  76                 "version", VERSION,
  77                 "API port", fmt.Sprintf(":%v", s.Port),
  78                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  79         )
  80
  81         var wg sync.WaitGroup
  82
  83         wg.Add(1)
  84         go func() {
  85                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
  86                 if err != nil {
  87                         s.Logger.Fatal(err)
  88                 }
  89
  90                 s.Logger.Fatal(s.Serve(ctx, ln))
  91         }()
  92
  93         wg.Add(1)
  94         go func() {
  95                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
  96                 if err != nil {
  97                         s.Logger.Fatal(err)
  98
  99                 }
 100
 101                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 102         }()
 103
 104         wg.Wait()
 105
 106         return nil
 107 }
 108
 109 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 110         for {
 111                 conn, err := ln.Accept()
 112                 if err != nil {
 113                         return err
 114                 }
 115
 116                 go func() {
 117                         defer func() { _ = conn.Close() }()
 118
 119                         err = s.handleFileTransfer(
 120                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 121                                         remoteAddr: conn.RemoteAddr().String(),
 122                                 }),
 123                                 conn,
 124                         )
 125
 126                         if err != nil {
 127                                 s.Logger.Errorw("file transfer error", "reason", err)
 128                         }
 129                 }()
 130         }
 131 }
 132
 133 func (s *Server) sendTransaction(t Transaction) error {
 134         requestNum := binary.BigEndian.Uint16(t.Type)
 135         clientID, err := byteToInt(*t.clientID)
 136         if err != nil {
 137                 return err
 138         }
 139
 140         s.mux.Lock()
 141         client := s.Clients[uint16(clientID)]
 142         s.mux.Unlock()
 143         if client == nil {
 144                 return fmt.Errorf("invalid client id %v", *t.clientID)
 145         }
 146         userName := string(client.UserName)
 147         login := client.Account.Login
 148
 149         handler := TransactionHandlers[requestNum]
 150
 151         b, err := t.MarshalBinary()
 152         if err != nil {
 153                 return err
 154         }
 155         var n int
 156         if n, err = client.Connection.Write(b); err != nil {
 157                 return err
 158         }
 159         s.Logger.Debugw("Sent Transaction",
 160                 "name", userName,
 161                 "login", login,
 162                 "IsReply", t.IsReply,
 163                 "type", handler.Name,
 164                 "sentBytes", n,
 165                 "remoteAddr", client.RemoteAddr,
 166         )
 167         return nil
 168 }
 169
 170 func (s *Server) processOutbox() {
 171         for {
 172                 t := <-s.outbox
 173                 go func() {
 174                         if err := s.sendTransaction(t); err != nil {
 175                                 s.Logger.Errorw("error sending transaction", "err", err)
 176                         }
 177                 }()
 178         }
 179 }
 180
 181 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 182         go s.processOutbox()
 183
 184         for {
 185                 conn, err := ln.Accept()
 186                 if err != nil {
 187                         s.Logger.Errorw("error accepting connection", "err", err)
 188                 }
 189                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 190                         remoteAddr: conn.RemoteAddr().String(),
 191                 })
 192
 193                 go func() {
 194                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 195                                 s.Logger.Infow("New client connection established", "RemoteAddr", conn.RemoteAddr())
 196                                 if err == io.EOF {
 197                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 198                                 } else {
 199                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 200                                 }
 201                         }
 202                 }()
 203         }
 204 }
 205
 206 const (
 207         agreementFile = "Agreement.txt"
 208 )
 209
 210 // NewServer constructs a new Server from a config dir
 211 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 212         server := Server{
 213                 Port:          netPort,
 214                 Accounts:      make(map[string]*Account),
 215                 Config:        new(Config),
 216                 Clients:       make(map[uint16]*ClientConn),
 217                 FileTransfers: make(map[uint32]*FileTransfer),
 218                 PrivateChats:  make(map[uint32]*PrivateChat),
 219                 ConfigDir:     configDir,
 220                 Logger:        logger,
 221                 NextGuestID:   new(uint16),
 222                 outbox:        make(chan Transaction),
 223                 Stats:         &Stats{StartTime: time.Now()},
 224                 ThreadedNews:  &ThreadedNews{},
 225                 FS:            FS,
 226         }
 227
 228         var err error
 229
 230         // generate a new random passID for tracker registration
 231         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 232                 return nil, err
 233         }
 234
 235         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 236         if err != nil {
 237                 return nil, err
 238         }
 239
 240         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 241                 return nil, err
 242         }
 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) writeThreadedNews() error {
 329         s.mux.Lock()
 330         defer s.mux.Unlock()
 331
 332         out, err := yaml.Marshal(s.ThreadedNews)
 333         if err != nil {
 334                 return err
 335         }
 336         err = ioutil.WriteFile(
 337                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 338                 out,
 339                 0666,
 340         )
 341         return err
 342 }
 343
 344 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 345         s.mux.Lock()
 346         defer s.mux.Unlock()
 347
 348         clientConn := &ClientConn{
 349                 ID:         &[]byte{0, 0},
 350                 Icon:       &[]byte{0, 0},
 351                 Flags:      &[]byte{0, 0},
 352                 UserName:   []byte{},
 353                 Connection: conn,
 354                 Server:     s,
 355                 Version:    &[]byte{},
 356                 AutoReply:  []byte{},
 357                 Transfers:  make(map[int][]*FileTransfer),
 358                 Agreed:     false,
 359                 RemoteAddr: remoteAddr,
 360         }
 361         *s.NextGuestID++
 362         ID := *s.NextGuestID
 363
 364         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 365         s.Clients[ID] = clientConn
 366
 367         return clientConn
 368 }
 369
 370 // NewUser creates a new user account entry in the server map and config file
 371 func (s *Server) NewUser(login, name, password string, access []byte) error {
 372         s.mux.Lock()
 373         defer s.mux.Unlock()
 374
 375         account := Account{
 376                 Login:    login,
 377                 Name:     name,
 378                 Password: hashAndSalt([]byte(password)),
 379                 Access:   &access,
 380         }
 381         out, err := yaml.Marshal(&account)
 382         if err != nil {
 383                 return err
 384         }
 385         s.Accounts[login] = &account
 386
 387         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 388 }
 389
 390 func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
 391         s.mux.Lock()
 392         defer s.mux.Unlock()
 393
 394         // update renames the user login
 395         if login != newLogin {
 396                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 397                 if err != nil {
 398                         return err
 399                 }
 400                 s.Accounts[newLogin] = s.Accounts[login]
 401                 delete(s.Accounts, login)
 402         }
 403
 404         account := s.Accounts[newLogin]
 405         account.Access = &access
 406         account.Name = name
 407         account.Password = password
 408
 409         out, err := yaml.Marshal(&account)
 410         if err != nil {
 411                 return err
 412         }
 413
 414         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 415                 return err
 416         }
 417
 418         return nil
 419 }
 420
 421 // DeleteUser deletes the user account
 422 func (s *Server) DeleteUser(login string) error {
 423         s.mux.Lock()
 424         defer s.mux.Unlock()
 425
 426         delete(s.Accounts, login)
 427
 428         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 429 }
 430
 431 func (s *Server) connectedUsers() []Field {
 432         s.mux.Lock()
 433         defer s.mux.Unlock()
 434
 435         var connectedUsers []Field
 436         for _, c := range sortedClients(s.Clients) {
 437                 if !c.Agreed {
 438                         continue
 439                 }
 440                 user := User{
 441                         ID:    *c.ID,
 442                         Icon:  *c.Icon,
 443                         Flags: *c.Flags,
 444                         Name:  string(c.UserName),
 445                 }
 446                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 447         }
 448         return connectedUsers
 449 }
 450
 451 // loadThreadedNews loads the threaded news data from disk
 452 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 453         fh, err := os.Open(threadedNewsPath)
 454         if err != nil {
 455                 return err
 456         }
 457         decoder := yaml.NewDecoder(fh)
 458
 459         return decoder.Decode(s.ThreadedNews)
 460 }
 461
 462 // loadAccounts loads account data from disk
 463 func (s *Server) loadAccounts(userDir string) error {
 464         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 465         if err != nil {
 466                 return err
 467         }
 468
 469         if len(matches) == 0 {
 470                 return errors.New("no user accounts found in " + userDir)
 471         }
 472
 473         for _, file := range matches {
 474                 fh, err := s.FS.Open(file)
 475                 if err != nil {
 476                         return err
 477                 }
 478
 479                 account := Account{}
 480                 decoder := yaml.NewDecoder(fh)
 481                 if err := decoder.Decode(&account); err != nil {
 482                         return err
 483                 }
 484
 485                 s.Accounts[account.Login] = &account
 486         }
 487         return nil
 488 }
 489
 490 func (s *Server) loadConfig(path string) error {
 491         fh, err := s.FS.Open(path)
 492         if err != nil {
 493                 return err
 494         }
 495
 496         decoder := yaml.NewDecoder(fh)
 497         err = decoder.Decode(s.Config)
 498         if err != nil {
 499                 return err
 500         }
 501
 502         validate := validator.New()
 503         err = validate.Struct(s.Config)
 504         if err != nil {
 505                 return err
 506         }
 507         return nil
 508 }
 509
 510 const (
 511         minTransactionLen = 22 // minimum length of any transaction
 512 )
 513
 514 // dontPanic recovers and logs panics instead of crashing
 515 // TODO: remove this after known issues are fixed
 516 func dontPanic(logger *zap.SugaredLogger) {
 517         if r := recover(); r != nil {
 518                 fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 519                 logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 520         }
 521 }
 522
 523 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 524 func (s *Server) handleNewConnection(ctx context.Context, conn io.ReadWriteCloser, remoteAddr string) error {
 525         defer dontPanic(s.Logger)
 526
 527         if err := Handshake(conn); err != nil {
 528                 return err
 529         }
 530
 531         buf := make([]byte, 1024)
 532         // TODO: fix potential short read with io.ReadFull
 533         readLen, err := conn.Read(buf)
 534         if readLen < minTransactionLen {
 535                 return err
 536         }
 537         if err != nil {
 538                 return err
 539         }
 540
 541         clientLogin, _, err := ReadTransaction(buf[:readLen])
 542         if err != nil {
 543                 return err
 544         }
 545
 546         c := s.NewClientConn(conn, remoteAddr)
 547         defer c.Disconnect()
 548
 549         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 550         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 551         *c.Version = clientLogin.GetField(fieldVersion).Data
 552
 553         var login string
 554         for _, char := range encodedLogin {
 555                 login += string(rune(255 - uint(char)))
 556         }
 557         if login == "" {
 558                 login = GuestAccount
 559         }
 560
 561         // If authentication fails, send error reply and close connection
 562         if !c.Authenticate(login, encodedPassword) {
 563                 t := c.NewErrReply(clientLogin, "Incorrect login.")
 564                 b, err := t.MarshalBinary()
 565                 if err != nil {
 566                         return err
 567                 }
 568                 if _, err := conn.Write(b); err != nil {
 569                         return err
 570                 }
 571                 return fmt.Errorf("incorrect login")
 572         }
 573
 574         if clientLogin.GetField(fieldUserName).Data != nil {
 575                 c.UserName = clientLogin.GetField(fieldUserName).Data
 576         }
 577
 578         if clientLogin.GetField(fieldUserIconID).Data != nil {
 579                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 580         }
 581
 582         c.Account = c.Server.Accounts[login]
 583
 584         if c.Authorize(accessDisconUser) {
 585                 *c.Flags = []byte{0, 2}
 586         }
 587
 588         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 589
 590         c.logger.Infow("Client connection received", "version", fmt.Sprintf("%x", *c.Version))
 591
 592         s.outbox <- c.NewReply(clientLogin,
 593                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 594                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 595                 NewField(fieldServerName, []byte(s.Config.Name)),
 596         )
 597
 598         // Send user access privs so client UI knows how to behave
 599         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 600
 601         // Show agreement to client
 602         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 603
 604         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 605         if *c.Version == nil || bytes.Equal(*c.Version, nostalgiaVersion) {
 606                 c.Agreed = true
 607                 c.logger = c.logger.With("name", string(c.UserName))
 608
 609                 for _, t := range c.notifyOthers(
 610                         *NewTransaction(
 611                                 tranNotifyChangeUser, nil,
 612                                 NewField(fieldUserName, c.UserName),
 613                                 NewField(fieldUserID, *c.ID),
 614                                 NewField(fieldUserIconID, *c.Icon),
 615                                 NewField(fieldUserFlags, *c.Flags),
 616                         ),
 617                 ) {
 618                         c.Server.outbox <- t
 619                 }
 620         }
 621
 622         c.Server.Stats.LoginCount += 1
 623
 624         const readBuffSize = 1024000 // 1KB - TODO: what should this be?
 625         tranBuff := make([]byte, 0)
 626         tReadlen := 0
 627         // Infinite loop where take action on incoming client requests until the connection is closed
 628         for {
 629                 buf = make([]byte, readBuffSize)
 630                 tranBuff = tranBuff[tReadlen:]
 631
 632                 readLen, err := c.Connection.Read(buf)
 633                 if err != nil {
 634                         return err
 635                 }
 636                 tranBuff = append(tranBuff, buf[:readLen]...)
 637
 638                 // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
 639                 // into a slice of transactions
 640                 var transactions []Transaction
 641                 if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
 642                         c.logger.Errorw("Error handling transaction", "err", err)
 643                 }
 644
 645                 // iterate over all the transactions that were parsed from the byte slice and handle them
 646                 for _, t := range transactions {
 647                         if err := c.handleTransaction(&t); err != nil {
 648                                 c.logger.Errorw("Error handling transaction", "err", err)
 649                         }
 650                 }
 651         }
 652 }
 653
 654 // NewTransactionRef generates a random ID for the file transfer.  The Hotline client includes this ID
 655 // in the transfer request payload, and the file transfer server will use it to map the request
 656 // to a transfer
 657 func (s *Server) NewTransactionRef() []byte {
 658         transactionRef := make([]byte, 4)
 659         rand.Read(transactionRef)
 660
 661         return transactionRef
 662 }
 663
 664 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 665         s.mux.Lock()
 666         defer s.mux.Unlock()
 667
 668         randID := make([]byte, 4)
 669         rand.Read(randID)
 670         data := binary.BigEndian.Uint32(randID[:])
 671
 672         s.PrivateChats[data] = &PrivateChat{
 673                 Subject:    "",
 674                 ClientConn: make(map[uint16]*ClientConn),
 675         }
 676         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 677
 678         return randID
 679 }
 680
 681 const dlFldrActionSendFile = 1
 682 const dlFldrActionResumeFile = 2
 683 const dlFldrActionNextFile = 3
 684
 685 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 686 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 687         defer dontPanic(s.Logger)
 688
 689         txBuf := make([]byte, 16)
 690         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 691                 return err
 692         }
 693
 694         var t transfer
 695         if _, err := t.Write(txBuf); err != nil {
 696                 return err
 697         }
 698
 699         transferRefNum := binary.BigEndian.Uint32(t.ReferenceNumber[:])
 700         defer func() {
 701                 s.mux.Lock()
 702                 delete(s.FileTransfers, transferRefNum)
 703                 s.mux.Unlock()
 704         }()
 705
 706         s.mux.Lock()
 707         fileTransfer, ok := s.FileTransfers[transferRefNum]
 708         s.mux.Unlock()
 709         if !ok {
 710                 return errors.New("invalid transaction ID")
 711         }
 712
 713         rLogger := s.Logger.With(
 714                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 715                 "xferID", transferRefNum,
 716         )
 717
 718         switch fileTransfer.Type {
 719         case bannerDownload:
 720                 if err := s.bannerDownload(rwc); err != nil {
 721                         return err
 722                 }
 723         case FileDownload:
 724                 s.Stats.DownloadCounter += 1
 725
 726                 fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 727                 if err != nil {
 728                         return err
 729                 }
 730
 731                 var dataOffset int64
 732                 if fileTransfer.fileResumeData != nil {
 733                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 734                 }
 735
 736                 fw, err := newFileWrapper(s.FS, fullFilePath, 0)
 737                 if err != nil {
 738                         return err
 739                 }
 740
 741                 rLogger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber)
 742
 743                 wr := bufio.NewWriterSize(rwc, 1460)
 744
 745                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 746                 if fileTransfer.options == nil {
 747                         // Start by sending flat file object to client
 748                         if _, err := wr.Write(fw.ffo.BinaryMarshal()); err != nil {
 749                                 return err
 750                         }
 751                 }
 752
 753                 file, err := fw.dataForkReader()
 754                 if err != nil {
 755                         return err
 756                 }
 757
 758                 if err := sendFile(wr, file, int(dataOffset)); err != nil {
 759                         return err
 760                 }
 761
 762                 if err := wr.Flush(); err != nil {
 763                         return err
 764                 }
 765
 766                 // if the client requested to resume transfer, do not send the resource fork, or it will be appended into the fileWrapper data
 767                 if fileTransfer.fileResumeData == nil {
 768                         err = binary.Write(wr, binary.BigEndian, fw.rsrcForkHeader())
 769                         if err != nil {
 770                                 return err
 771                         }
 772                         if err := wr.Flush(); err != nil {
 773                                 return err
 774                         }
 775                 }
 776
 777                 rFile, err := fw.rsrcForkFile()
 778                 if err != nil {
 779                         return nil
 780                 }
 781
 782                 err = sendFile(wr, rFile, int(dataOffset))
 783                 if err != nil {
 784                         return err
 785                 }
 786
 787                 if err := wr.Flush(); err != nil {
 788                         return err
 789                 }
 790
 791         case FileUpload:
 792                 s.Stats.UploadCounter += 1
 793
 794                 destinationFile, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 795                 if err != nil {
 796                         return err
 797                 }
 798
 799                 var file *os.File
 800
 801                 // A file upload has three possible cases:
 802                 // 1) Upload a new file
 803                 // 2) Resume a partially transferred file
 804                 // 3) Replace a fully uploaded file
 805                 //  We have to infer which case applies by inspecting what is already on the filesystem
 806
 807                 // 1) Check for existing file:
 808                 _, err = os.Stat(destinationFile)
 809                 if err == nil {
 810                         // If found, that means this upload is intended to replace the file
 811                         if err = os.Remove(destinationFile); err != nil {
 812                                 return err
 813                         }
 814                         file, err = os.Create(destinationFile + incompleteFileSuffix)
 815                 }
 816                 if errors.Is(err, fs.ErrNotExist) {
 817                         // If not found, open or create a new .incomplete file
 818                         file, err = os.OpenFile(destinationFile+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 819                         if err != nil {
 820                                 return err
 821                         }
 822                 }
 823
 824                 f, err := newFileWrapper(s.FS, destinationFile, 0)
 825                 if err != nil {
 826                         return err
 827                 }
 828
 829                 s.Logger.Infow("File upload started", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
 830
 831                 rForkWriter := io.Discard
 832                 iForkWriter := io.Discard
 833                 if s.Config.PreserveResourceForks {
 834                         rForkWriter, err = f.rsrcForkWriter()
 835                         if err != nil {
 836                                 return err
 837                         }
 838
 839                         iForkWriter, err = f.infoForkWriter()
 840                         if err != nil {
 841                                 return err
 842                         }
 843                 }
 844
 845                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter); err != nil {
 846                         return err
 847                 }
 848
 849                 if err := file.Close(); err != nil {
 850                         return err
 851                 }
 852
 853                 if err := s.FS.Rename(destinationFile+".incomplete", destinationFile); err != nil {
 854                         return err
 855                 }
 856
 857                 s.Logger.Infow("File upload complete", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
 858         case FolderDownload:
 859                 // Folder Download flow:
 860                 // 1. Get filePath from the transfer
 861                 // 2. Iterate over files
 862                 // 3. For each fileWrapper:
 863                 //       Send fileWrapper header to client
 864                 // The client can reply in 3 ways:
 865                 //
 866                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 867                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 868                 //
 869                 // 2. If download of a fileWrapper is to be resumed:
 870                 //              client sends:
 871                 //                      []byte{0x00, 0x02} // download folder action
 872                 //                      [2]byte // Resume data size
 873                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 874                 //
 875                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 876                 //
 877                 // When download is requested (case 2 or 3), server replies with:
 878                 //                      [4]byte - fileWrapper size
 879                 //                      []byte  - Flattened File Object
 880                 //
 881                 // After every fileWrapper download, client could request next fileWrapper with:
 882                 //                      []byte{0x00, 0x03}
 883                 //
 884                 // This notifies the server to send the next item header
 885
 886                 fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 887                 if err != nil {
 888                         return err
 889                 }
 890
 891                 basePathLen := len(fullFilePath)
 892
 893                 s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber)
 894
 895                 nextAction := make([]byte, 2)
 896                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 897                         return err
 898                 }
 899
 900                 i := 0
 901                 err = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, err error) error {
 902                         s.Stats.DownloadCounter += 1
 903                         i += 1
 904
 905                         if err != nil {
 906                                 return err
 907                         }
 908
 909                         // skip dot files
 910                         if strings.HasPrefix(info.Name(), ".") {
 911                                 return nil
 912                         }
 913
 914                         hlFile, err := newFileWrapper(s.FS, path, 0)
 915                         if err != nil {
 916                                 return err
 917                         }
 918
 919                         subPath := path[basePathLen+1:]
 920                         s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())
 921
 922                         if i == 1 {
 923                                 return nil
 924                         }
 925
 926                         fileHeader := NewFileHeader(subPath, info.IsDir())
 927
 928                         // Send the fileWrapper header to client
 929                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 930                                 s.Logger.Errorf("error sending file header: %v", err)
 931                                 return err
 932                         }
 933
 934                         // Read the client's Next Action request
 935                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 936                                 return err
 937                         }
 938
 939                         s.Logger.Infow("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 940
 941                         var dataOffset int64
 942
 943                         switch nextAction[1] {
 944                         case dlFldrActionResumeFile:
 945                                 // get size of resumeData
 946                                 resumeDataByteLen := make([]byte, 2)
 947                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 948                                         return err
 949                                 }
 950
 951                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 952                                 resumeDataBytes := make([]byte, resumeDataLen)
 953                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 954                                         return err
 955                                 }
 956
 957                                 var frd FileResumeData
 958                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 959                                         return err
 960                                 }
 961                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 962                         case dlFldrActionNextFile:
 963                                 // client asked to skip this file
 964                                 return nil
 965                         }
 966
 967                         if info.IsDir() {
 968                                 return nil
 969                         }
 970
 971                         s.Logger.Infow("File download started",
 972                                 "fileName", info.Name(),
 973                                 "transactionRef", fileTransfer.ReferenceNumber,
 974                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
 975                         )
 976
 977                         // Send file size to client
 978                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
 979                                 s.Logger.Error(err)
 980                                 return err
 981                         }
 982
 983                         // Send ffo bytes to client
 984                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
 985                                 s.Logger.Error(err)
 986                                 return err
 987                         }
 988
 989                         file, err := s.FS.Open(path)
 990                         if err != nil {
 991                                 return err
 992                         }
 993
 994                         // wr := bufio.NewWriterSize(rwc, 1460)
 995                         err = sendFile(rwc, file, int(dataOffset))
 996                         if err != nil {
 997                                 return err
 998                         }
 999
1000                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1001                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1002                                 if err != nil {
1003                                         return err
1004                                 }
1005
1006                                 rFile, err := hlFile.rsrcForkFile()
1007                                 if err != nil {
1008                                         return err
1009                                 }
1010
1011                                 err = sendFile(rwc, rFile, int(dataOffset))
1012                                 if err != nil {
1013                                         return err
1014                                 }
1015                         }
1016
1017                         // Read the client's Next Action request.  This is always 3, I think?
1018                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1019                                 return err
1020                         }
1021
1022                         return nil
1023                 })
1024
1025                 if err != nil {
1026                         return err
1027                 }
1028
1029         case FolderUpload:
1030                 dstPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
1031                 if err != nil {
1032                         return err
1033                 }
1034
1035                 s.Logger.Infow(
1036                         "Folder upload started",
1037                         "transactionRef", fileTransfer.ReferenceNumber,
1038                         "dstPath", dstPath,
1039                         "TransferSize", fmt.Sprintf("%x", fileTransfer.TransferSize),
1040                         "FolderItemCount", fileTransfer.FolderItemCount,
1041                 )
1042
1043                 // Check if the target folder exists.  If not, create it.
1044                 if _, err := s.FS.Stat(dstPath); os.IsNotExist(err) {
1045                         if err := s.FS.Mkdir(dstPath, 0777); err != nil {
1046                                 return err
1047                         }
1048                 }
1049
1050                 // Begin the folder upload flow by sending the "next file action" to client
1051                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1052                         return err
1053                 }
1054
1055                 fileSize := make([]byte, 4)
1056
1057                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1058                         s.Stats.UploadCounter += 1
1059
1060                         var fu folderUpload
1061                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1062                                 return err
1063                         }
1064                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1065                                 return err
1066                         }
1067                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1068                                 return err
1069                         }
1070
1071                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1072
1073                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1074                                 return err
1075                         }
1076
1077                         s.Logger.Infow(
1078                                 "Folder upload continued",
1079                                 "transactionRef", fmt.Sprintf("%x", fileTransfer.ReferenceNumber),
1080                                 "FormattedPath", fu.FormattedPath(),
1081                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1082                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1083                         )
1084
1085                         if fu.IsFolder == [2]byte{0, 1} {
1086                                 if _, err := os.Stat(filepath.Join(dstPath, fu.FormattedPath())); os.IsNotExist(err) {
1087                                         if err := os.Mkdir(filepath.Join(dstPath, fu.FormattedPath()), 0777); err != nil {
1088                                                 return err
1089                                         }
1090                                 }
1091
1092                                 // Tell client to send next file
1093                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1094                                         return err
1095                                 }
1096                         } else {
1097                                 nextAction := dlFldrActionSendFile
1098
1099                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1100                                 _, err = os.Stat(filepath.Join(dstPath, fu.FormattedPath()))
1101                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1102                                         return err
1103                                 }
1104                                 if err == nil {
1105                                         nextAction = dlFldrActionNextFile
1106                                 }
1107
1108                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1109                                 incompleteFile, err := os.Stat(filepath.Join(dstPath, fu.FormattedPath()+incompleteFileSuffix))
1110                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1111                                         return err
1112                                 }
1113                                 if err == nil {
1114                                         nextAction = dlFldrActionResumeFile
1115                                 }
1116
1117                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1118                                         return err
1119                                 }
1120
1121                                 switch nextAction {
1122                                 case dlFldrActionNextFile:
1123                                         continue
1124                                 case dlFldrActionResumeFile:
1125                                         offset := make([]byte, 4)
1126                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1127
1128                                         file, err := os.OpenFile(dstPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1129                                         if err != nil {
1130                                                 return err
1131                                         }
1132
1133                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1134
1135                                         b, _ := fileResumeData.BinaryMarshal()
1136
1137                                         bs := make([]byte, 2)
1138                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1139
1140                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1141                                                 return err
1142                                         }
1143
1144                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1145                                                 return err
1146                                         }
1147
1148                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard); err != nil {
1149                                                 s.Logger.Error(err)
1150                                         }
1151
1152                                         err = os.Rename(dstPath+"/"+fu.FormattedPath()+".incomplete", dstPath+"/"+fu.FormattedPath())
1153                                         if err != nil {
1154                                                 return err
1155                                         }
1156
1157                                 case dlFldrActionSendFile:
1158                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1159                                                 return err
1160                                         }
1161
1162                                         filePath := filepath.Join(dstPath, fu.FormattedPath())
1163
1164                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1165                                         if err != nil {
1166                                                 return err
1167                                         }
1168
1169                                         s.Logger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1170
1171                                         incWriter, err := hlFile.incFileWriter()
1172                                         if err != nil {
1173                                                 return err
1174                                         }
1175
1176                                         rForkWriter := io.Discard
1177                                         iForkWriter := io.Discard
1178                                         if s.Config.PreserveResourceForks {
1179                                                 iForkWriter, err = hlFile.infoForkWriter()
1180                                                 if err != nil {
1181                                                         return err
1182                                                 }
1183
1184                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1185                                                 if err != nil {
1186                                                         return err
1187                                                 }
1188                                         }
1189                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter); err != nil {
1190                                                 return err
1191                                         }
1192                                         // _ = newFile.Close()
1193                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1194                                                 return err
1195                                         }
1196                                 }
1197
1198                                 // Tell client to send next fileWrapper
1199                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1200                                         return err
1201                                 }
1202                         }
1203                 }
1204                 s.Logger.Infof("Folder upload complete")
1205         }
1206
1207         return nil
1208 }