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                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 197
 198                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 199                                 if err == io.EOF {
 200                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 201                                 } else {
 202                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 203                                 }
 204                         }
 205                 }()
 206         }
 207 }
 208
 209 const (
 210         agreementFile = "Agreement.txt"
 211 )
 212
 213 // NewServer constructs a new Server from a config dir
 214 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 215         server := Server{
 216                 Port:          netPort,
 217                 Accounts:      make(map[string]*Account),
 218                 Config:        new(Config),
 219                 Clients:       make(map[uint16]*ClientConn),
 220                 fileTransfers: make(map[[4]byte]*FileTransfer),
 221                 PrivateChats:  make(map[uint32]*PrivateChat),
 222                 ConfigDir:     configDir,
 223                 Logger:        logger,
 224                 NextGuestID:   new(uint16),
 225                 outbox:        make(chan Transaction),
 226                 Stats:         &Stats{StartTime: time.Now()},
 227                 ThreadedNews:  &ThreadedNews{},
 228                 FS:            FS,
 229         }
 230
 231         var err error
 232
 233         // generate a new random passID for tracker registration
 234         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 235                 return nil, err
 236         }
 237
 238         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 239         if err != nil {
 240                 return nil, err
 241         }
 242
 243         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 244                 return nil, err
 245         }
 246
 247         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 248                 return nil, err
 249         }
 250
 251         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 252                 return nil, err
 253         }
 254
 255         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 256                 return nil, err
 257         }
 258
 259         server.Config.FileRoot = filepath.Join(configDir, "Files")
 260
 261         *server.NextGuestID = 1
 262
 263         if server.Config.EnableTrackerRegistration {
 264                 server.Logger.Infow(
 265                         "Tracker registration enabled",
 266                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 267                         "trackers", server.Config.Trackers,
 268                 )
 269
 270                 go func() {
 271                         for {
 272                                 tr := &TrackerRegistration{
 273                                         UserCount:   server.userCount(),
 274                                         PassID:      server.TrackerPassID[:],
 275                                         Name:        server.Config.Name,
 276                                         Description: server.Config.Description,
 277                                 }
 278                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 279                                 for _, t := range server.Config.Trackers {
 280                                         if err := register(t, tr); err != nil {
 281                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 282                                         }
 283                                         server.Logger.Infow("Sent Tracker registration", "data", tr)
 284                                 }
 285
 286                                 time.Sleep(trackerUpdateFrequency * time.Second)
 287                         }
 288                 }()
 289         }
 290
 291         // Start Client Keepalive go routine
 292         go server.keepaliveHandler()
 293
 294         return &server, nil
 295 }
 296
 297 func (s *Server) userCount() int {
 298         s.mux.Lock()
 299         defer s.mux.Unlock()
 300
 301         return len(s.Clients)
 302 }
 303
 304 func (s *Server) keepaliveHandler() {
 305         for {
 306                 time.Sleep(idleCheckInterval * time.Second)
 307                 s.mux.Lock()
 308
 309                 for _, c := range s.Clients {
 310                         c.IdleTime += idleCheckInterval
 311                         if c.IdleTime > userIdleSeconds && !c.Idle {
 312                                 c.Idle = true
 313
 314                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
 315                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 316                                 binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
 317
 318                                 c.sendAll(
 319                                         tranNotifyChangeUser,
 320                                         NewField(fieldUserID, *c.ID),
 321                                         NewField(fieldUserFlags, *c.Flags),
 322                                         NewField(fieldUserName, c.UserName),
 323                                         NewField(fieldUserIconID, *c.Icon),
 324                                 )
 325                         }
 326                 }
 327                 s.mux.Unlock()
 328         }
 329 }
 330
 331 func (s *Server) writeThreadedNews() error {
 332         s.mux.Lock()
 333         defer s.mux.Unlock()
 334
 335         out, err := yaml.Marshal(s.ThreadedNews)
 336         if err != nil {
 337                 return err
 338         }
 339         err = ioutil.WriteFile(
 340                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 341                 out,
 342                 0666,
 343         )
 344         return err
 345 }
 346
 347 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 348         s.mux.Lock()
 349         defer s.mux.Unlock()
 350
 351         clientConn := &ClientConn{
 352                 ID:         &[]byte{0, 0},
 353                 Icon:       &[]byte{0, 0},
 354                 Flags:      &[]byte{0, 0},
 355                 UserName:   []byte{},
 356                 Connection: conn,
 357                 Server:     s,
 358                 Version:    &[]byte{},
 359                 AutoReply:  []byte{},
 360                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 361                 Agreed:     false,
 362                 RemoteAddr: remoteAddr,
 363         }
 364         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 365                 FileDownload:   {},
 366                 FileUpload:     {},
 367                 FolderDownload: {},
 368                 FolderUpload:   {},
 369                 bannerDownload: {},
 370         }
 371
 372         *s.NextGuestID++
 373         ID := *s.NextGuestID
 374
 375         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 376         s.Clients[ID] = clientConn
 377
 378         return clientConn
 379 }
 380
 381 // NewUser creates a new user account entry in the server map and config file
 382 func (s *Server) NewUser(login, name, password string, access []byte) error {
 383         s.mux.Lock()
 384         defer s.mux.Unlock()
 385
 386         account := Account{
 387                 Login:    login,
 388                 Name:     name,
 389                 Password: hashAndSalt([]byte(password)),
 390                 Access:   &access,
 391         }
 392         out, err := yaml.Marshal(&account)
 393         if err != nil {
 394                 return err
 395         }
 396         s.Accounts[login] = &account
 397
 398         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 399 }
 400
 401 func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
 402         s.mux.Lock()
 403         defer s.mux.Unlock()
 404
 405         // update renames the user login
 406         if login != newLogin {
 407                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 408                 if err != nil {
 409                         return err
 410                 }
 411                 s.Accounts[newLogin] = s.Accounts[login]
 412                 delete(s.Accounts, login)
 413         }
 414
 415         account := s.Accounts[newLogin]
 416         account.Access = &access
 417         account.Name = name
 418         account.Password = password
 419
 420         out, err := yaml.Marshal(&account)
 421         if err != nil {
 422                 return err
 423         }
 424
 425         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 426                 return err
 427         }
 428
 429         return nil
 430 }
 431
 432 // DeleteUser deletes the user account
 433 func (s *Server) DeleteUser(login string) error {
 434         s.mux.Lock()
 435         defer s.mux.Unlock()
 436
 437         delete(s.Accounts, login)
 438
 439         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 440 }
 441
 442 func (s *Server) connectedUsers() []Field {
 443         s.mux.Lock()
 444         defer s.mux.Unlock()
 445
 446         var connectedUsers []Field
 447         for _, c := range sortedClients(s.Clients) {
 448                 if !c.Agreed {
 449                         continue
 450                 }
 451                 user := User{
 452                         ID:    *c.ID,
 453                         Icon:  *c.Icon,
 454                         Flags: *c.Flags,
 455                         Name:  string(c.UserName),
 456                 }
 457                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 458         }
 459         return connectedUsers
 460 }
 461
 462 // loadThreadedNews loads the threaded news data from disk
 463 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 464         fh, err := os.Open(threadedNewsPath)
 465         if err != nil {
 466                 return err
 467         }
 468         decoder := yaml.NewDecoder(fh)
 469
 470         return decoder.Decode(s.ThreadedNews)
 471 }
 472
 473 // loadAccounts loads account data from disk
 474 func (s *Server) loadAccounts(userDir string) error {
 475         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 476         if err != nil {
 477                 return err
 478         }
 479
 480         if len(matches) == 0 {
 481                 return errors.New("no user accounts found in " + userDir)
 482         }
 483
 484         for _, file := range matches {
 485                 fh, err := s.FS.Open(file)
 486                 if err != nil {
 487                         return err
 488                 }
 489
 490                 account := Account{}
 491                 decoder := yaml.NewDecoder(fh)
 492                 if err := decoder.Decode(&account); err != nil {
 493                         return err
 494                 }
 495
 496                 s.Accounts[account.Login] = &account
 497         }
 498         return nil
 499 }
 500
 501 func (s *Server) loadConfig(path string) error {
 502         fh, err := s.FS.Open(path)
 503         if err != nil {
 504                 return err
 505         }
 506
 507         decoder := yaml.NewDecoder(fh)
 508         err = decoder.Decode(s.Config)
 509         if err != nil {
 510                 return err
 511         }
 512
 513         validate := validator.New()
 514         err = validate.Struct(s.Config)
 515         if err != nil {
 516                 return err
 517         }
 518         return nil
 519 }
 520
 521 const (
 522         minTransactionLen = 22 // minimum length of any transaction
 523 )
 524
 525 // dontPanic recovers and logs panics instead of crashing
 526 // TODO: remove this after known issues are fixed
 527 func dontPanic(logger *zap.SugaredLogger) {
 528         if r := recover(); r != nil {
 529                 fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 530                 logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 531         }
 532 }
 533
 534 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 535 func (s *Server) handleNewConnection(ctx context.Context, conn io.ReadWriteCloser, remoteAddr string) error {
 536         defer dontPanic(s.Logger)
 537
 538         if err := Handshake(conn); err != nil {
 539                 return err
 540         }
 541
 542         buf := make([]byte, 1024)
 543         // TODO: fix potential short read with io.ReadFull
 544         readLen, err := conn.Read(buf)
 545         if readLen < minTransactionLen {
 546                 return err
 547         }
 548         if err != nil {
 549                 return err
 550         }
 551
 552         clientLogin, _, err := ReadTransaction(buf[:readLen])
 553         if err != nil {
 554                 return err
 555         }
 556
 557         c := s.NewClientConn(conn, remoteAddr)
 558         defer c.Disconnect()
 559
 560         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 561         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 562         *c.Version = clientLogin.GetField(fieldVersion).Data
 563
 564         var login string
 565         for _, char := range encodedLogin {
 566                 login += string(rune(255 - uint(char)))
 567         }
 568         if login == "" {
 569                 login = GuestAccount
 570         }
 571
 572         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 573
 574         // If authentication fails, send error reply and close connection
 575         if !c.Authenticate(login, encodedPassword) {
 576                 t := c.NewErrReply(clientLogin, "Incorrect login.")
 577                 b, err := t.MarshalBinary()
 578                 if err != nil {
 579                         return err
 580                 }
 581                 if _, err := conn.Write(b); err != nil {
 582                         return err
 583                 }
 584
 585                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", *c.Version))
 586
 587                 return nil
 588         }
 589
 590         if clientLogin.GetField(fieldUserName).Data != nil {
 591                 c.UserName = clientLogin.GetField(fieldUserName).Data
 592         }
 593
 594         if clientLogin.GetField(fieldUserIconID).Data != nil {
 595                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 596         }
 597
 598         c.Account = c.Server.Accounts[login]
 599
 600         if c.Authorize(accessDisconUser) {
 601                 *c.Flags = []byte{0, 2}
 602         }
 603
 604         s.outbox <- c.NewReply(clientLogin,
 605                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 606                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 607                 NewField(fieldServerName, []byte(s.Config.Name)),
 608         )
 609
 610         // Send user access privs so client UI knows how to behave
 611         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 612
 613         // Show agreement to client
 614         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 615
 616         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 617         if *c.Version == nil || bytes.Equal(*c.Version, nostalgiaVersion) {
 618                 c.Agreed = true
 619                 c.logger = c.logger.With("name", string(c.UserName))
 620                 c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%x", *c.Version))
 621
 622                 for _, t := range c.notifyOthers(
 623                         *NewTransaction(
 624                                 tranNotifyChangeUser, nil,
 625                                 NewField(fieldUserName, c.UserName),
 626                                 NewField(fieldUserID, *c.ID),
 627                                 NewField(fieldUserIconID, *c.Icon),
 628                                 NewField(fieldUserFlags, *c.Flags),
 629                         ),
 630                 ) {
 631                         c.Server.outbox <- t
 632                 }
 633         }
 634
 635         c.Server.Stats.LoginCount += 1
 636
 637         const readBuffSize = 1024000 // 1KB - TODO: what should this be?
 638         tranBuff := make([]byte, 0)
 639         tReadlen := 0
 640         // Infinite loop where take action on incoming client requests until the connection is closed
 641         for {
 642                 buf = make([]byte, readBuffSize)
 643                 tranBuff = tranBuff[tReadlen:]
 644
 645                 readLen, err := c.Connection.Read(buf)
 646                 if err != nil {
 647                         return err
 648                 }
 649                 tranBuff = append(tranBuff, buf[:readLen]...)
 650
 651                 // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
 652                 // into a slice of transactions
 653                 var transactions []Transaction
 654                 if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
 655                         c.logger.Errorw("Error handling transaction", "err", err)
 656                 }
 657
 658                 // iterate over all the transactions that were parsed from the byte slice and handle them
 659                 for _, t := range transactions {
 660                         if err := c.handleTransaction(&t); err != nil {
 661                                 c.logger.Errorw("Error handling transaction", "err", err)
 662                         }
 663                 }
 664         }
 665 }
 666
 667 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 668         s.mux.Lock()
 669         defer s.mux.Unlock()
 670
 671         randID := make([]byte, 4)
 672         rand.Read(randID)
 673         data := binary.BigEndian.Uint32(randID[:])
 674
 675         s.PrivateChats[data] = &PrivateChat{
 676                 Subject:    "",
 677                 ClientConn: make(map[uint16]*ClientConn),
 678         }
 679         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 680
 681         return randID
 682 }
 683
 684 const dlFldrActionSendFile = 1
 685 const dlFldrActionResumeFile = 2
 686 const dlFldrActionNextFile = 3
 687
 688 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 689 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 690         defer dontPanic(s.Logger)
 691
 692         txBuf := make([]byte, 16)
 693         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 694                 return err
 695         }
 696
 697         var t transfer
 698         if _, err := t.Write(txBuf); err != nil {
 699                 return err
 700         }
 701
 702         defer func() {
 703                 s.mux.Lock()
 704                 delete(s.fileTransfers, t.ReferenceNumber)
 705                 s.mux.Unlock()
 706
 707         }()
 708
 709         s.mux.Lock()
 710         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 711         s.mux.Unlock()
 712         if !ok {
 713                 return errors.New("invalid transaction ID")
 714         }
 715
 716         defer func() {
 717                 fileTransfer.ClientConn.transfersMU.Lock()
 718                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 719                 fileTransfer.ClientConn.transfersMU.Unlock()
 720         }()
 721
 722         rLogger := s.Logger.With(
 723                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 724                 "login", fileTransfer.ClientConn.Account.Login,
 725                 "name", string(fileTransfer.ClientConn.UserName),
 726         )
 727
 728         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 729         if err != nil {
 730                 return err
 731         }
 732
 733         switch fileTransfer.Type {
 734         case bannerDownload:
 735                 if err := s.bannerDownload(rwc); err != nil {
 736                         panic(err)
 737                         return err
 738                 }
 739         case FileDownload:
 740                 s.Stats.DownloadCounter += 1
 741
 742                 var dataOffset int64
 743                 if fileTransfer.fileResumeData != nil {
 744                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 745                 }
 746
 747                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 748                 if err != nil {
 749                         return err
 750                 }
 751
 752                 rLogger.Infow("File download started", "filePath", fullPath)
 753
 754                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 755                 if fileTransfer.options == nil {
 756                         // Start by sending flat file object to client
 757                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 758                                 return err
 759                         }
 760                 }
 761
 762                 file, err := fw.dataForkReader()
 763                 if err != nil {
 764                         return err
 765                 }
 766
 767                 br := bufio.NewReader(file)
 768                 if _, err := br.Discard(int(dataOffset)); err != nil {
 769                         return err
 770                 }
 771
 772                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 773                         return err
 774                 }
 775
 776                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 777                 if fileTransfer.fileResumeData == nil {
 778                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 779                         if err != nil {
 780                                 return err
 781                         }
 782                 }
 783
 784                 rFile, err := fw.rsrcForkFile()
 785                 if err != nil {
 786                         return nil
 787                 }
 788
 789                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 790                         return err
 791                 }
 792
 793         case FileUpload:
 794                 s.Stats.UploadCounter += 1
 795
 796                 var file *os.File
 797
 798                 // A file upload has three possible cases:
 799                 // 1) Upload a new file
 800                 // 2) Resume a partially transferred file
 801                 // 3) Replace a fully uploaded file
 802                 //  We have to infer which case applies by inspecting what is already on the filesystem
 803
 804                 // 1) Check for existing file:
 805                 _, err = os.Stat(fullPath)
 806                 if err == nil {
 807                         return errors.New("existing file found at " + fullPath)
 808                 }
 809                 if errors.Is(err, fs.ErrNotExist) {
 810                         // If not found, open or create a new .incomplete file
 811                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 812                         if err != nil {
 813                                 return err
 814                         }
 815                 }
 816
 817                 f, err := newFileWrapper(s.FS, fullPath, 0)
 818                 if err != nil {
 819                         return err
 820                 }
 821
 822                 rLogger.Infow("File upload started", "dstFile", fullPath)
 823
 824                 rForkWriter := io.Discard
 825                 iForkWriter := io.Discard
 826                 if s.Config.PreserveResourceForks {
 827                         rForkWriter, err = f.rsrcForkWriter()
 828                         if err != nil {
 829                                 return err
 830                         }
 831
 832                         iForkWriter, err = f.infoForkWriter()
 833                         if err != nil {
 834                                 return err
 835                         }
 836                 }
 837
 838                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 839                         s.Logger.Error(err)
 840                 }
 841
 842                 if err := file.Close(); err != nil {
 843                         return err
 844                 }
 845
 846                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 847                         return err
 848                 }
 849
 850                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 851         case FolderDownload:
 852                 // Folder Download flow:
 853                 // 1. Get filePath from the transfer
 854                 // 2. Iterate over files
 855                 // 3. For each fileWrapper:
 856                 //       Send fileWrapper header to client
 857                 // The client can reply in 3 ways:
 858                 //
 859                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 860                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 861                 //
 862                 // 2. If download of a fileWrapper is to be resumed:
 863                 //              client sends:
 864                 //                      []byte{0x00, 0x02} // download folder action
 865                 //                      [2]byte // Resume data size
 866                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 867                 //
 868                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 869                 //
 870                 // When download is requested (case 2 or 3), server replies with:
 871                 //                      [4]byte - fileWrapper size
 872                 //                      []byte  - Flattened File Object
 873                 //
 874                 // After every fileWrapper download, client could request next fileWrapper with:
 875                 //                      []byte{0x00, 0x03}
 876                 //
 877                 // This notifies the server to send the next item header
 878
 879                 basePathLen := len(fullPath)
 880
 881                 rLogger.Infow("Start folder download", "path", fullPath)
 882
 883                 nextAction := make([]byte, 2)
 884                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 885                         return err
 886                 }
 887
 888                 i := 0
 889                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 890                         s.Stats.DownloadCounter += 1
 891                         i += 1
 892
 893                         if err != nil {
 894                                 return err
 895                         }
 896
 897                         // skip dot files
 898                         if strings.HasPrefix(info.Name(), ".") {
 899                                 return nil
 900                         }
 901
 902                         hlFile, err := newFileWrapper(s.FS, path, 0)
 903                         if err != nil {
 904                                 return err
 905                         }
 906
 907                         subPath := path[basePathLen+1:]
 908                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 909
 910                         if i == 1 {
 911                                 return nil
 912                         }
 913
 914                         fileHeader := NewFileHeader(subPath, info.IsDir())
 915
 916                         // Send the fileWrapper header to client
 917                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 918                                 s.Logger.Errorf("error sending file header: %v", err)
 919                                 return err
 920                         }
 921
 922                         // Read the client's Next Action request
 923                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 924                                 return err
 925                         }
 926
 927                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 928
 929                         var dataOffset int64
 930
 931                         switch nextAction[1] {
 932                         case dlFldrActionResumeFile:
 933                                 // get size of resumeData
 934                                 resumeDataByteLen := make([]byte, 2)
 935                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 936                                         return err
 937                                 }
 938
 939                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 940                                 resumeDataBytes := make([]byte, resumeDataLen)
 941                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 942                                         return err
 943                                 }
 944
 945                                 var frd FileResumeData
 946                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 947                                         return err
 948                                 }
 949                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 950                         case dlFldrActionNextFile:
 951                                 // client asked to skip this file
 952                                 return nil
 953                         }
 954
 955                         if info.IsDir() {
 956                                 return nil
 957                         }
 958
 959                         rLogger.Infow("File download started",
 960                                 "fileName", info.Name(),
 961                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
 962                         )
 963
 964                         // Send file size to client
 965                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
 966                                 s.Logger.Error(err)
 967                                 return err
 968                         }
 969
 970                         // Send ffo bytes to client
 971                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
 972                                 s.Logger.Error(err)
 973                                 return err
 974                         }
 975
 976                         file, err := s.FS.Open(path)
 977                         if err != nil {
 978                                 return err
 979                         }
 980
 981                         // wr := bufio.NewWriterSize(rwc, 1460)
 982                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
 983                                 return err
 984                         }
 985
 986                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
 987                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
 988                                 if err != nil {
 989                                         return err
 990                                 }
 991
 992                                 rFile, err := hlFile.rsrcForkFile()
 993                                 if err != nil {
 994                                         return err
 995                                 }
 996
 997                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 998                                         return err
 999                                 }
1000                         }
1001
1002                         // Read the client's Next Action request.  This is always 3, I think?
1003                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1004                                 return err
1005                         }
1006
1007                         return nil
1008                 })
1009
1010                 if err != nil {
1011                         return err
1012                 }
1013
1014         case FolderUpload:
1015                 rLogger.Infow(
1016                         "Folder upload started",
1017                         "dstPath", fullPath,
1018                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1019                         "FolderItemCount", fileTransfer.FolderItemCount,
1020                 )
1021
1022                 // Check if the target folder exists.  If not, create it.
1023                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1024                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1025                                 return err
1026                         }
1027                 }
1028
1029                 // Begin the folder upload flow by sending the "next file action" to client
1030                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1031                         return err
1032                 }
1033
1034                 fileSize := make([]byte, 4)
1035
1036                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1037                         s.Stats.UploadCounter += 1
1038
1039                         var fu folderUpload
1040                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1041                                 return err
1042                         }
1043                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1044                                 return err
1045                         }
1046                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1047                                 return err
1048                         }
1049
1050                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1051
1052                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1053                                 return err
1054                         }
1055
1056                         rLogger.Infow(
1057                                 "Folder upload continued",
1058                                 "FormattedPath", fu.FormattedPath(),
1059                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1060                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1061                         )
1062
1063                         if fu.IsFolder == [2]byte{0, 1} {
1064                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1065                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1066                                                 return err
1067                                         }
1068                                 }
1069
1070                                 // Tell client to send next file
1071                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1072                                         return err
1073                                 }
1074                         } else {
1075                                 nextAction := dlFldrActionSendFile
1076
1077                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1078                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1079                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1080                                         return err
1081                                 }
1082                                 if err == nil {
1083                                         nextAction = dlFldrActionNextFile
1084                                 }
1085
1086                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1087                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1088                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1089                                         return err
1090                                 }
1091                                 if err == nil {
1092                                         nextAction = dlFldrActionResumeFile
1093                                 }
1094
1095                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1096                                         return err
1097                                 }
1098
1099                                 switch nextAction {
1100                                 case dlFldrActionNextFile:
1101                                         continue
1102                                 case dlFldrActionResumeFile:
1103                                         offset := make([]byte, 4)
1104                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1105
1106                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1107                                         if err != nil {
1108                                                 return err
1109                                         }
1110
1111                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1112
1113                                         b, _ := fileResumeData.BinaryMarshal()
1114
1115                                         bs := make([]byte, 2)
1116                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1117
1118                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1119                                                 return err
1120                                         }
1121
1122                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1123                                                 return err
1124                                         }
1125
1126                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1127                                                 s.Logger.Error(err)
1128                                         }
1129
1130                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1131                                         if err != nil {
1132                                                 return err
1133                                         }
1134
1135                                 case dlFldrActionSendFile:
1136                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1137                                                 return err
1138                                         }
1139
1140                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1141
1142                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1143                                         if err != nil {
1144                                                 return err
1145                                         }
1146
1147                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1148
1149                                         incWriter, err := hlFile.incFileWriter()
1150                                         if err != nil {
1151                                                 return err
1152                                         }
1153
1154                                         rForkWriter := io.Discard
1155                                         iForkWriter := io.Discard
1156                                         if s.Config.PreserveResourceForks {
1157                                                 iForkWriter, err = hlFile.infoForkWriter()
1158                                                 if err != nil {
1159                                                         return err
1160                                                 }
1161
1162                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1163                                                 if err != nil {
1164                                                         return err
1165                                                 }
1166                                         }
1167                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1168                                                 return err
1169                                         }
1170
1171                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1172                                                 return err
1173                                         }
1174                                 }
1175
1176                                 // Tell client to send next fileWrapper
1177                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1178                                         return err
1179                                 }
1180                         }
1181                 }
1182                 rLogger.Infof("Folder upload complete")
1183         }
1184
1185         return nil
1186 }