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
  71 type PrivateChat struct {
  72         Subject    string
  73         ClientConn map[uint16]*ClientConn
  74 }
  75
  76 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  77         s.Logger.Infow("Hotline server started",
  78                 "version", VERSION,
  79                 "API port", fmt.Sprintf(":%v", s.Port),
  80                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  81         )
  82
  83         var wg sync.WaitGroup
  84
  85         wg.Add(1)
  86         go func() {
  87                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
  88                 if err != nil {
  89                         s.Logger.Fatal(err)
  90                 }
  91
  92                 s.Logger.Fatal(s.Serve(ctx, ln))
  93         }()
  94
  95         wg.Add(1)
  96         go func() {
  97                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
  98                 if err != nil {
  99                         s.Logger.Fatal(err)
 100
 101                 }
 102
 103                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 104         }()
 105
 106         wg.Wait()
 107
 108         return nil
 109 }
 110
 111 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 112         for {
 113                 conn, err := ln.Accept()
 114                 if err != nil {
 115                         return err
 116                 }
 117
 118                 go func() {
 119                         defer func() { _ = conn.Close() }()
 120
 121                         err = s.handleFileTransfer(
 122                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 123                                         remoteAddr: conn.RemoteAddr().String(),
 124                                 }),
 125                                 conn,
 126                         )
 127
 128                         if err != nil {
 129                                 s.Logger.Errorw("file transfer error", "reason", err)
 130                         }
 131                 }()
 132         }
 133 }
 134
 135 func (s *Server) sendTransaction(t Transaction) error {
 136         requestNum := binary.BigEndian.Uint16(t.Type)
 137         clientID, err := byteToInt(*t.clientID)
 138         if err != nil {
 139                 return err
 140         }
 141
 142         s.mux.Lock()
 143         client := s.Clients[uint16(clientID)]
 144         s.mux.Unlock()
 145         if client == nil {
 146                 return fmt.Errorf("invalid client id %v", *t.clientID)
 147         }
 148         userName := string(client.UserName)
 149         login := client.Account.Login
 150
 151         handler := TransactionHandlers[requestNum]
 152
 153         b, err := t.MarshalBinary()
 154         if err != nil {
 155                 return err
 156         }
 157         var n int
 158         if n, err = client.Connection.Write(b); err != nil {
 159                 return err
 160         }
 161         s.Logger.Debugw("Sent Transaction",
 162                 "name", userName,
 163                 "login", login,
 164                 "IsReply", t.IsReply,
 165                 "type", handler.Name,
 166                 "sentBytes", n,
 167                 "remoteAddr", client.RemoteAddr,
 168         )
 169         return nil
 170 }
 171
 172 func (s *Server) processOutbox() {
 173         for {
 174                 t := <-s.outbox
 175                 go func() {
 176                         if err := s.sendTransaction(t); err != nil {
 177                                 s.Logger.Errorw("error sending transaction", "err", err)
 178                         }
 179                 }()
 180         }
 181 }
 182
 183 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 184         go s.processOutbox()
 185
 186         for {
 187                 conn, err := ln.Accept()
 188                 if err != nil {
 189                         s.Logger.Errorw("error accepting connection", "err", err)
 190                 }
 191                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 192                         remoteAddr: conn.RemoteAddr().String(),
 193                 })
 194
 195                 go func() {
 196                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 197                                 s.Logger.Infow("New client connection established", "RemoteAddr", conn.RemoteAddr())
 198                                 if err == io.EOF {
 199                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 200                                 } else {
 201                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 202                                 }
 203                         }
 204                 }()
 205         }
 206 }
 207
 208 const (
 209         agreementFile = "Agreement.txt"
 210 )
 211
 212 // NewServer constructs a new Server from a config dir
 213 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 214         server := Server{
 215                 Port:          netPort,
 216                 Accounts:      make(map[string]*Account),
 217                 Config:        new(Config),
 218                 Clients:       make(map[uint16]*ClientConn),
 219                 fileTransfers: make(map[[4]byte]*FileTransfer),
 220                 PrivateChats:  make(map[uint32]*PrivateChat),
 221                 ConfigDir:     configDir,
 222                 Logger:        logger,
 223                 NextGuestID:   new(uint16),
 224                 outbox:        make(chan Transaction),
 225                 Stats:         &Stats{StartTime: time.Now()},
 226                 ThreadedNews:  &ThreadedNews{},
 227                 FS:            FS,
 228         }
 229
 230         var err error
 231
 232         // generate a new random passID for tracker registration
 233         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 234                 return nil, err
 235         }
 236
 237         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 238         if err != nil {
 239                 return nil, err
 240         }
 241
 242         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 243                 return nil, err
 244         }
 245
 246         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 247                 return nil, err
 248         }
 249
 250         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 251                 return nil, err
 252         }
 253
 254         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 255                 return nil, err
 256         }
 257
 258         server.Config.FileRoot = filepath.Join(configDir, "Files")
 259
 260         *server.NextGuestID = 1
 261
 262         if server.Config.EnableTrackerRegistration {
 263                 server.Logger.Infow(
 264                         "Tracker registration enabled",
 265                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 266                         "trackers", server.Config.Trackers,
 267                 )
 268
 269                 go func() {
 270                         for {
 271                                 tr := &TrackerRegistration{
 272                                         UserCount:   server.userCount(),
 273                                         PassID:      server.TrackerPassID[:],
 274                                         Name:        server.Config.Name,
 275                                         Description: server.Config.Description,
 276                                 }
 277                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 278                                 for _, t := range server.Config.Trackers {
 279                                         if err := register(t, tr); err != nil {
 280                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 281                                         }
 282                                         server.Logger.Infow("Sent Tracker registration", "data", tr)
 283                                 }
 284
 285                                 time.Sleep(trackerUpdateFrequency * time.Second)
 286                         }
 287                 }()
 288         }
 289
 290         // Start Client Keepalive go routine
 291         go server.keepaliveHandler()
 292
 293         return &server, nil
 294 }
 295
 296 func (s *Server) userCount() int {
 297         s.mux.Lock()
 298         defer s.mux.Unlock()
 299
 300         return len(s.Clients)
 301 }
 302
 303 func (s *Server) keepaliveHandler() {
 304         for {
 305                 time.Sleep(idleCheckInterval * time.Second)
 306                 s.mux.Lock()
 307
 308                 for _, c := range s.Clients {
 309                         c.IdleTime += idleCheckInterval
 310                         if c.IdleTime > userIdleSeconds && !c.Idle {
 311                                 c.Idle = true
 312
 313                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
 314                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 315                                 binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
 316
 317                                 c.sendAll(
 318                                         tranNotifyChangeUser,
 319                                         NewField(fieldUserID, *c.ID),
 320                                         NewField(fieldUserFlags, *c.Flags),
 321                                         NewField(fieldUserName, c.UserName),
 322                                         NewField(fieldUserIconID, *c.Icon),
 323                                 )
 324                         }
 325                 }
 326                 s.mux.Unlock()
 327         }
 328 }
 329
 330 func (s *Server) writeThreadedNews() error {
 331         s.mux.Lock()
 332         defer s.mux.Unlock()
 333
 334         out, err := yaml.Marshal(s.ThreadedNews)
 335         if err != nil {
 336                 return err
 337         }
 338         err = ioutil.WriteFile(
 339                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 340                 out,
 341                 0666,
 342         )
 343         return err
 344 }
 345
 346 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 347         s.mux.Lock()
 348         defer s.mux.Unlock()
 349
 350         clientConn := &ClientConn{
 351                 ID:         &[]byte{0, 0},
 352                 Icon:       &[]byte{0, 0},
 353                 Flags:      &[]byte{0, 0},
 354                 UserName:   []byte{},
 355                 Connection: conn,
 356                 Server:     s,
 357                 Version:    &[]byte{},
 358                 AutoReply:  []byte{},
 359                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 360                 Agreed:     false,
 361                 RemoteAddr: remoteAddr,
 362         }
 363         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 364                 FileDownload:   {},
 365                 FileUpload:     {},
 366                 FolderDownload: {},
 367                 FolderUpload:   {},
 368                 bannerDownload: {},
 369         }
 370
 371         *s.NextGuestID++
 372         ID := *s.NextGuestID
 373
 374         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 375         s.Clients[ID] = clientConn
 376
 377         return clientConn
 378 }
 379
 380 // NewUser creates a new user account entry in the server map and config file
 381 func (s *Server) NewUser(login, name, password string, access []byte) error {
 382         s.mux.Lock()
 383         defer s.mux.Unlock()
 384
 385         account := Account{
 386                 Login:    login,
 387                 Name:     name,
 388                 Password: hashAndSalt([]byte(password)),
 389                 Access:   &access,
 390         }
 391         out, err := yaml.Marshal(&account)
 392         if err != nil {
 393                 return err
 394         }
 395         s.Accounts[login] = &account
 396
 397         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 398 }
 399
 400 func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
 401         s.mux.Lock()
 402         defer s.mux.Unlock()
 403
 404         // update renames the user login
 405         if login != newLogin {
 406                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 407                 if err != nil {
 408                         return err
 409                 }
 410                 s.Accounts[newLogin] = s.Accounts[login]
 411                 delete(s.Accounts, login)
 412         }
 413
 414         account := s.Accounts[newLogin]
 415         account.Access = &access
 416         account.Name = name
 417         account.Password = password
 418
 419         out, err := yaml.Marshal(&account)
 420         if err != nil {
 421                 return err
 422         }
 423
 424         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 425                 return err
 426         }
 427
 428         return nil
 429 }
 430
 431 // DeleteUser deletes the user account
 432 func (s *Server) DeleteUser(login string) error {
 433         s.mux.Lock()
 434         defer s.mux.Unlock()
 435
 436         delete(s.Accounts, login)
 437
 438         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 439 }
 440
 441 func (s *Server) connectedUsers() []Field {
 442         s.mux.Lock()
 443         defer s.mux.Unlock()
 444
 445         var connectedUsers []Field
 446         for _, c := range sortedClients(s.Clients) {
 447                 if !c.Agreed {
 448                         continue
 449                 }
 450                 user := User{
 451                         ID:    *c.ID,
 452                         Icon:  *c.Icon,
 453                         Flags: *c.Flags,
 454                         Name:  string(c.UserName),
 455                 }
 456                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 457         }
 458         return connectedUsers
 459 }
 460
 461 // loadThreadedNews loads the threaded news data from disk
 462 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 463         fh, err := os.Open(threadedNewsPath)
 464         if err != nil {
 465                 return err
 466         }
 467         decoder := yaml.NewDecoder(fh)
 468
 469         return decoder.Decode(s.ThreadedNews)
 470 }
 471
 472 // loadAccounts loads account data from disk
 473 func (s *Server) loadAccounts(userDir string) error {
 474         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 475         if err != nil {
 476                 return err
 477         }
 478
 479         if len(matches) == 0 {
 480                 return errors.New("no user accounts found in " + userDir)
 481         }
 482
 483         for _, file := range matches {
 484                 fh, err := s.FS.Open(file)
 485                 if err != nil {
 486                         return err
 487                 }
 488
 489                 account := Account{}
 490                 decoder := yaml.NewDecoder(fh)
 491                 if err := decoder.Decode(&account); err != nil {
 492                         return err
 493                 }
 494
 495                 s.Accounts[account.Login] = &account
 496         }
 497         return nil
 498 }
 499
 500 func (s *Server) loadConfig(path string) error {
 501         fh, err := s.FS.Open(path)
 502         if err != nil {
 503                 return err
 504         }
 505
 506         decoder := yaml.NewDecoder(fh)
 507         err = decoder.Decode(s.Config)
 508         if err != nil {
 509                 return err
 510         }
 511
 512         validate := validator.New()
 513         err = validate.Struct(s.Config)
 514         if err != nil {
 515                 return err
 516         }
 517         return nil
 518 }
 519
 520 const (
 521         minTransactionLen = 22 // minimum length of any transaction
 522 )
 523
 524 // dontPanic recovers and logs panics instead of crashing
 525 // TODO: remove this after known issues are fixed
 526 func dontPanic(logger *zap.SugaredLogger) {
 527         if r := recover(); r != nil {
 528                 fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 529                 logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 530         }
 531 }
 532
 533 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 534 func (s *Server) handleNewConnection(ctx context.Context, conn io.ReadWriteCloser, remoteAddr string) error {
 535         defer dontPanic(s.Logger)
 536
 537         if err := Handshake(conn); err != nil {
 538                 return err
 539         }
 540
 541         buf := make([]byte, 1024)
 542         // TODO: fix potential short read with io.ReadFull
 543         readLen, err := conn.Read(buf)
 544         if readLen < minTransactionLen {
 545                 return err
 546         }
 547         if err != nil {
 548                 return err
 549         }
 550
 551         clientLogin, _, err := ReadTransaction(buf[:readLen])
 552         if err != nil {
 553                 return err
 554         }
 555
 556         c := s.NewClientConn(conn, remoteAddr)
 557         defer c.Disconnect()
 558
 559         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 560         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 561         *c.Version = clientLogin.GetField(fieldVersion).Data
 562
 563         var login string
 564         for _, char := range encodedLogin {
 565                 login += string(rune(255 - uint(char)))
 566         }
 567         if login == "" {
 568                 login = GuestAccount
 569         }
 570
 571         // If authentication fails, send error reply and close connection
 572         if !c.Authenticate(login, encodedPassword) {
 573                 t := c.NewErrReply(clientLogin, "Incorrect login.")
 574                 b, err := t.MarshalBinary()
 575                 if err != nil {
 576                         return err
 577                 }
 578                 if _, err := conn.Write(b); err != nil {
 579                         return err
 580                 }
 581                 return fmt.Errorf("incorrect login")
 582         }
 583
 584         if clientLogin.GetField(fieldUserName).Data != nil {
 585                 c.UserName = clientLogin.GetField(fieldUserName).Data
 586         }
 587
 588         if clientLogin.GetField(fieldUserIconID).Data != nil {
 589                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 590         }
 591
 592         c.Account = c.Server.Accounts[login]
 593
 594         if c.Authorize(accessDisconUser) {
 595                 *c.Flags = []byte{0, 2}
 596         }
 597
 598         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 599
 600         c.logger.Infow("Client connection received", "version", fmt.Sprintf("%x", *c.Version))
 601
 602         s.outbox <- c.NewReply(clientLogin,
 603                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 604                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 605                 NewField(fieldServerName, []byte(s.Config.Name)),
 606         )
 607
 608         // Send user access privs so client UI knows how to behave
 609         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 610
 611         // Show agreement to client
 612         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 613
 614         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 615         if *c.Version == nil || bytes.Equal(*c.Version, nostalgiaVersion) {
 616                 c.Agreed = true
 617                 c.logger = c.logger.With("name", string(c.UserName))
 618
 619                 for _, t := range c.notifyOthers(
 620                         *NewTransaction(
 621                                 tranNotifyChangeUser, nil,
 622                                 NewField(fieldUserName, c.UserName),
 623                                 NewField(fieldUserID, *c.ID),
 624                                 NewField(fieldUserIconID, *c.Icon),
 625                                 NewField(fieldUserFlags, *c.Flags),
 626                         ),
 627                 ) {
 628                         c.Server.outbox <- t
 629                 }
 630         }
 631
 632         c.Server.Stats.LoginCount += 1
 633
 634         const readBuffSize = 1024000 // 1KB - TODO: what should this be?
 635         tranBuff := make([]byte, 0)
 636         tReadlen := 0
 637         // Infinite loop where take action on incoming client requests until the connection is closed
 638         for {
 639                 buf = make([]byte, readBuffSize)
 640                 tranBuff = tranBuff[tReadlen:]
 641
 642                 readLen, err := c.Connection.Read(buf)
 643                 if err != nil {
 644                         return err
 645                 }
 646                 tranBuff = append(tranBuff, buf[:readLen]...)
 647
 648                 // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
 649                 // into a slice of transactions
 650                 var transactions []Transaction
 651                 if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
 652                         c.logger.Errorw("Error handling transaction", "err", err)
 653                 }
 654
 655                 // iterate over all the transactions that were parsed from the byte slice and handle them
 656                 for _, t := range transactions {
 657                         if err := c.handleTransaction(&t); err != nil {
 658                                 c.logger.Errorw("Error handling transaction", "err", err)
 659                         }
 660                 }
 661         }
 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         defer func() {
 700                 s.mux.Lock()
 701                 delete(s.fileTransfers, t.ReferenceNumber)
 702                 s.mux.Unlock()
 703
 704         }()
 705
 706         s.mux.Lock()
 707         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 708         s.mux.Unlock()
 709         if !ok {
 710                 return errors.New("invalid transaction ID")
 711         }
 712
 713         defer func() {
 714                 fileTransfer.ClientConn.transfersMU.Lock()
 715                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 716                 fileTransfer.ClientConn.transfersMU.Unlock()
 717         }()
 718
 719         rLogger := s.Logger.With(
 720                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 721                 "login", fileTransfer.ClientConn.Account.Login,
 722                 "name", string(fileTransfer.ClientConn.UserName),
 723         )
 724
 725         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 726         if err != nil {
 727                 return err
 728         }
 729
 730         switch fileTransfer.Type {
 731         case bannerDownload:
 732                 if err := s.bannerDownload(rwc); err != nil {
 733                         panic(err)
 734                         return err
 735                 }
 736         case FileDownload:
 737                 s.Stats.DownloadCounter += 1
 738
 739                 var dataOffset int64
 740                 if fileTransfer.fileResumeData != nil {
 741                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 742                 }
 743
 744                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 745                 if err != nil {
 746                         return err
 747                 }
 748
 749                 rLogger.Infow("File download started", "filePath", fullPath)
 750
 751                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 752                 if fileTransfer.options == nil {
 753                         // Start by sending flat file object to client
 754                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 755                                 return err
 756                         }
 757                 }
 758
 759                 file, err := fw.dataForkReader()
 760                 if err != nil {
 761                         return err
 762                 }
 763
 764                 br := bufio.NewReader(file)
 765                 if _, err := br.Discard(int(dataOffset)); err != nil {
 766                         return err
 767                 }
 768
 769                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 770                         return err
 771                 }
 772
 773                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 774                 if fileTransfer.fileResumeData == nil {
 775                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 776                         if err != nil {
 777                                 return err
 778                         }
 779                 }
 780
 781                 rFile, err := fw.rsrcForkFile()
 782                 if err != nil {
 783                         return nil
 784                 }
 785
 786                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 787                         return err
 788                 }
 789
 790         case FileUpload:
 791                 s.Stats.UploadCounter += 1
 792
 793                 var file *os.File
 794
 795                 // A file upload has three possible cases:
 796                 // 1) Upload a new file
 797                 // 2) Resume a partially transferred file
 798                 // 3) Replace a fully uploaded file
 799                 //  We have to infer which case applies by inspecting what is already on the filesystem
 800
 801                 // 1) Check for existing file:
 802                 _, err = os.Stat(fullPath)
 803                 if err == nil {
 804                         return errors.New("existing file found at " + fullPath)
 805                 }
 806                 if errors.Is(err, fs.ErrNotExist) {
 807                         // If not found, open or create a new .incomplete file
 808                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 809                         if err != nil {
 810                                 return err
 811                         }
 812                 }
 813
 814                 f, err := newFileWrapper(s.FS, fullPath, 0)
 815                 if err != nil {
 816                         return err
 817                 }
 818
 819                 rLogger.Infow("File upload started", "dstFile", fullPath)
 820
 821                 rForkWriter := io.Discard
 822                 iForkWriter := io.Discard
 823                 if s.Config.PreserveResourceForks {
 824                         rForkWriter, err = f.rsrcForkWriter()
 825                         if err != nil {
 826                                 return err
 827                         }
 828
 829                         iForkWriter, err = f.infoForkWriter()
 830                         if err != nil {
 831                                 return err
 832                         }
 833                 }
 834
 835                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 836                         s.Logger.Error(err)
 837                 }
 838
 839                 if err := file.Close(); err != nil {
 840                         return err
 841                 }
 842
 843                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 844                         return err
 845                 }
 846
 847                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 848         case FolderDownload:
 849                 // Folder Download flow:
 850                 // 1. Get filePath from the transfer
 851                 // 2. Iterate over files
 852                 // 3. For each fileWrapper:
 853                 //       Send fileWrapper header to client
 854                 // The client can reply in 3 ways:
 855                 //
 856                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 857                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 858                 //
 859                 // 2. If download of a fileWrapper is to be resumed:
 860                 //              client sends:
 861                 //                      []byte{0x00, 0x02} // download folder action
 862                 //                      [2]byte // Resume data size
 863                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 864                 //
 865                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 866                 //
 867                 // When download is requested (case 2 or 3), server replies with:
 868                 //                      [4]byte - fileWrapper size
 869                 //                      []byte  - Flattened File Object
 870                 //
 871                 // After every fileWrapper download, client could request next fileWrapper with:
 872                 //                      []byte{0x00, 0x03}
 873                 //
 874                 // This notifies the server to send the next item header
 875
 876                 basePathLen := len(fullPath)
 877
 878                 rLogger.Infow("Start folder download", "path", fullPath)
 879
 880                 nextAction := make([]byte, 2)
 881                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 882                         return err
 883                 }
 884
 885                 i := 0
 886                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 887                         s.Stats.DownloadCounter += 1
 888                         i += 1
 889
 890                         if err != nil {
 891                                 return err
 892                         }
 893
 894                         // skip dot files
 895                         if strings.HasPrefix(info.Name(), ".") {
 896                                 return nil
 897                         }
 898
 899                         hlFile, err := newFileWrapper(s.FS, path, 0)
 900                         if err != nil {
 901                                 return err
 902                         }
 903
 904                         subPath := path[basePathLen+1:]
 905                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 906
 907                         if i == 1 {
 908                                 return nil
 909                         }
 910
 911                         fileHeader := NewFileHeader(subPath, info.IsDir())
 912
 913                         // Send the fileWrapper header to client
 914                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 915                                 s.Logger.Errorf("error sending file header: %v", err)
 916                                 return err
 917                         }
 918
 919                         // Read the client's Next Action request
 920                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 921                                 return err
 922                         }
 923
 924                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 925
 926                         var dataOffset int64
 927
 928                         switch nextAction[1] {
 929                         case dlFldrActionResumeFile:
 930                                 // get size of resumeData
 931                                 resumeDataByteLen := make([]byte, 2)
 932                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 933                                         return err
 934                                 }
 935
 936                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 937                                 resumeDataBytes := make([]byte, resumeDataLen)
 938                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 939                                         return err
 940                                 }
 941
 942                                 var frd FileResumeData
 943                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 944                                         return err
 945                                 }
 946                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 947                         case dlFldrActionNextFile:
 948                                 // client asked to skip this file
 949                                 return nil
 950                         }
 951
 952                         if info.IsDir() {
 953                                 return nil
 954                         }
 955
 956                         rLogger.Infow("File download started",
 957                                 "fileName", info.Name(),
 958                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
 959                         )
 960
 961                         // Send file size to client
 962                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
 963                                 s.Logger.Error(err)
 964                                 return err
 965                         }
 966
 967                         // Send ffo bytes to client
 968                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
 969                                 s.Logger.Error(err)
 970                                 return err
 971                         }
 972
 973                         file, err := s.FS.Open(path)
 974                         if err != nil {
 975                                 return err
 976                         }
 977
 978                         // wr := bufio.NewWriterSize(rwc, 1460)
 979                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
 980                                 return err
 981                         }
 982
 983                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
 984                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
 985                                 if err != nil {
 986                                         return err
 987                                 }
 988
 989                                 rFile, err := hlFile.rsrcForkFile()
 990                                 if err != nil {
 991                                         return err
 992                                 }
 993
 994                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 995                                         return err
 996                                 }
 997                         }
 998
 999                         // Read the client's Next Action request.  This is always 3, I think?
1000                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1001                                 return err
1002                         }
1003
1004                         return nil
1005                 })
1006
1007                 if err != nil {
1008                         return err
1009                 }
1010
1011         case FolderUpload:
1012                 rLogger.Infow(
1013                         "Folder upload started",
1014                         "dstPath", fullPath,
1015                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1016                         "FolderItemCount", fileTransfer.FolderItemCount,
1017                 )
1018
1019                 // Check if the target folder exists.  If not, create it.
1020                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1021                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1022                                 return err
1023                         }
1024                 }
1025
1026                 // Begin the folder upload flow by sending the "next file action" to client
1027                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1028                         return err
1029                 }
1030
1031                 fileSize := make([]byte, 4)
1032
1033                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1034                         s.Stats.UploadCounter += 1
1035
1036                         var fu folderUpload
1037                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1038                                 return err
1039                         }
1040                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1041                                 return err
1042                         }
1043                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1044                                 return err
1045                         }
1046
1047                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1048
1049                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1050                                 return err
1051                         }
1052
1053                         rLogger.Infow(
1054                                 "Folder upload continued",
1055                                 "FormattedPath", fu.FormattedPath(),
1056                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1057                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1058                         )
1059
1060                         if fu.IsFolder == [2]byte{0, 1} {
1061                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1062                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1063                                                 return err
1064                                         }
1065                                 }
1066
1067                                 // Tell client to send next file
1068                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1069                                         return err
1070                                 }
1071                         } else {
1072                                 nextAction := dlFldrActionSendFile
1073
1074                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1075                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1076                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1077                                         return err
1078                                 }
1079                                 if err == nil {
1080                                         nextAction = dlFldrActionNextFile
1081                                 }
1082
1083                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1084                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1085                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1086                                         return err
1087                                 }
1088                                 if err == nil {
1089                                         nextAction = dlFldrActionResumeFile
1090                                 }
1091
1092                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1093                                         return err
1094                                 }
1095
1096                                 switch nextAction {
1097                                 case dlFldrActionNextFile:
1098                                         continue
1099                                 case dlFldrActionResumeFile:
1100                                         offset := make([]byte, 4)
1101                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1102
1103                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1104                                         if err != nil {
1105                                                 return err
1106                                         }
1107
1108                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1109
1110                                         b, _ := fileResumeData.BinaryMarshal()
1111
1112                                         bs := make([]byte, 2)
1113                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1114
1115                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1116                                                 return err
1117                                         }
1118
1119                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1120                                                 return err
1121                                         }
1122
1123                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1124                                                 s.Logger.Error(err)
1125                                         }
1126
1127                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1128                                         if err != nil {
1129                                                 return err
1130                                         }
1131
1132                                 case dlFldrActionSendFile:
1133                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1134                                                 return err
1135                                         }
1136
1137                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1138
1139                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1140                                         if err != nil {
1141                                                 return err
1142                                         }
1143
1144                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1145
1146                                         incWriter, err := hlFile.incFileWriter()
1147                                         if err != nil {
1148                                                 return err
1149                                         }
1150
1151                                         rForkWriter := io.Discard
1152                                         iForkWriter := io.Discard
1153                                         if s.Config.PreserveResourceForks {
1154                                                 iForkWriter, err = hlFile.infoForkWriter()
1155                                                 if err != nil {
1156                                                         return err
1157                                                 }
1158
1159                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1160                                                 if err != nil {
1161                                                         return err
1162                                                 }
1163                                         }
1164                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1165                                                 return err
1166                                         }
1167
1168                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1169                                                 return err
1170                                         }
1171                                 }
1172
1173                                 // Tell client to send next fileWrapper
1174                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1175                                         return err
1176                                 }
1177                         }
1178                 }
1179                 rLogger.Infof("Folder upload complete")
1180         }
1181
1182         return nil
1183 }