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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "context"
   6         "encoding/binary"
   7         "errors"
   8         "fmt"
   9         "github.com/go-playground/validator/v10"
  10         "go.uber.org/zap"
  11         "gopkg.in/yaml.v3"
  12         "io"
  13         "io/fs"
  14         "io/ioutil"
  15         "math/big"
  16         "math/rand"
  17         "net"
  18         "os"
  19         "path/filepath"
  20         "strings"
  21         "sync"
  22         "time"
  23 )
  24
  25 type contextKey string
  26
  27 var contextKeyReq = contextKey("req")
  28
  29 type requestCtx struct {
  30         remoteAddr string
  31         login      string
  32         name       string
  33 }
  34
  35 type Server struct {
  36         Port          int
  37         Accounts      map[string]*Account
  38         Agreement     []byte
  39         Clients       map[uint16]*ClientConn
  40         fileTransfers map[[4]byte]*FileTransfer
  41
  42         Config    *Config
  43         ConfigDir string
  44         Logger    *zap.SugaredLogger
  45
  46         PrivateChatsMu sync.Mutex
  47         PrivateChats   map[uint32]*PrivateChat
  48
  49         NextGuestID   *uint16
  50         TrackerPassID [4]byte
  51
  52         StatsMu sync.Mutex
  53         Stats   *Stats
  54
  55         FS FileStore // Storage backend to use for File storage
  56
  57         outbox chan Transaction
  58         mux    sync.Mutex
  59
  60         threadedNewsMux sync.Mutex
  61         ThreadedNews    *ThreadedNews
  62
  63         flatNewsMux sync.Mutex
  64         FlatNews    []byte
  65
  66         banListMU sync.Mutex
  67         banList   map[string]*time.Time
  68 }
  69
  70 func (s *Server) CurrentStats() Stats {
  71         s.StatsMu.Lock()
  72         defer s.StatsMu.Unlock()
  73
  74         stats := s.Stats
  75         stats.CurrentlyConnected = len(s.Clients)
  76
  77         return *stats
  78 }
  79
  80 type PrivateChat struct {
  81         Subject    string
  82         ClientConn map[uint16]*ClientConn
  83 }
  84
  85 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  86         s.Logger.Infow("Hotline server started",
  87                 "version", VERSION,
  88                 "API port", fmt.Sprintf(":%v", s.Port),
  89                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  90         )
  91
  92         var wg sync.WaitGroup
  93
  94         wg.Add(1)
  95         go func() {
  96                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
  97                 if err != nil {
  98                         s.Logger.Fatal(err)
  99                 }
 100
 101                 s.Logger.Fatal(s.Serve(ctx, ln))
 102         }()
 103
 104         wg.Add(1)
 105         go func() {
 106                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
 107                 if err != nil {
 108                         s.Logger.Fatal(err)
 109
 110                 }
 111
 112                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 113         }()
 114
 115         wg.Wait()
 116
 117         return nil
 118 }
 119
 120 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 121         for {
 122                 conn, err := ln.Accept()
 123                 if err != nil {
 124                         return err
 125                 }
 126
 127                 go func() {
 128                         defer func() { _ = conn.Close() }()
 129
 130                         err = s.handleFileTransfer(
 131                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 132                                         remoteAddr: conn.RemoteAddr().String(),
 133                                 }),
 134                                 conn,
 135                         )
 136
 137                         if err != nil {
 138                                 s.Logger.Errorw("file transfer error", "reason", err)
 139                         }
 140                 }()
 141         }
 142 }
 143
 144 func (s *Server) sendTransaction(t Transaction) error {
 145         clientID, err := byteToInt(*t.clientID)
 146         if err != nil {
 147                 return err
 148         }
 149
 150         s.mux.Lock()
 151         client := s.Clients[uint16(clientID)]
 152         s.mux.Unlock()
 153         if client == nil {
 154                 return fmt.Errorf("invalid client id %v", *t.clientID)
 155         }
 156
 157         b, err := t.MarshalBinary()
 158         if err != nil {
 159                 return err
 160         }
 161
 162         _, err = client.Connection.Write(b)
 163         if err != nil {
 164                 return err
 165         }
 166
 167         return nil
 168 }
 169
 170 func (s *Server) processOutbox() {
 171         for {
 172                 t := <-s.outbox
 173                 go func() {
 174                         if err := s.sendTransaction(t); err != nil {
 175                                 s.Logger.Errorw("error sending transaction", "err", err)
 176                         }
 177                 }()
 178         }
 179 }
 180
 181 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 182         go s.processOutbox()
 183
 184         for {
 185                 conn, err := ln.Accept()
 186                 if err != nil {
 187                         s.Logger.Errorw("error accepting connection", "err", err)
 188                 }
 189                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 190                         remoteAddr: conn.RemoteAddr().String(),
 191                 })
 192
 193                 go func() {
 194                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 195
 196                         defer conn.Close()
 197                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 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{Since: time.Now()},
 226                 ThreadedNews:  &ThreadedNews{},
 227                 FS:            FS,
 228                 banList:       make(map[string]*time.Time),
 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         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 248         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 249
 250         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 251                 return nil, err
 252         }
 253
 254         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 255                 return nil, err
 256         }
 257
 258         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 259                 return nil, err
 260         }
 261
 262         server.Config.FileRoot = filepath.Join(configDir, "Files")
 263
 264         *server.NextGuestID = 1
 265
 266         if server.Config.EnableTrackerRegistration {
 267                 server.Logger.Infow(
 268                         "Tracker registration enabled",
 269                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 270                         "trackers", server.Config.Trackers,
 271                 )
 272
 273                 go func() {
 274                         for {
 275                                 tr := &TrackerRegistration{
 276                                         UserCount:   server.userCount(),
 277                                         PassID:      server.TrackerPassID[:],
 278                                         Name:        server.Config.Name,
 279                                         Description: server.Config.Description,
 280                                 }
 281                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 282                                 for _, t := range server.Config.Trackers {
 283                                         if err := register(t, tr); err != nil {
 284                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 285                                         }
 286                                         server.Logger.Debugw("Sent Tracker registration", "addr", t)
 287                                 }
 288
 289                                 time.Sleep(trackerUpdateFrequency * time.Second)
 290                         }
 291                 }()
 292         }
 293
 294         // Start Client Keepalive go routine
 295         go server.keepaliveHandler()
 296
 297         return &server, nil
 298 }
 299
 300 func (s *Server) userCount() int {
 301         s.mux.Lock()
 302         defer s.mux.Unlock()
 303
 304         return len(s.Clients)
 305 }
 306
 307 func (s *Server) keepaliveHandler() {
 308         for {
 309                 time.Sleep(idleCheckInterval * time.Second)
 310                 s.mux.Lock()
 311
 312                 for _, c := range s.Clients {
 313                         c.IdleTime += idleCheckInterval
 314                         if c.IdleTime > userIdleSeconds && !c.Idle {
 315                                 c.Idle = true
 316
 317                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 318                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 319                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 320
 321                                 c.sendAll(
 322                                         tranNotifyChangeUser,
 323                                         NewField(fieldUserID, *c.ID),
 324                                         NewField(fieldUserFlags, c.Flags),
 325                                         NewField(fieldUserName, c.UserName),
 326                                         NewField(fieldUserIconID, c.Icon),
 327                                 )
 328                         }
 329                 }
 330                 s.mux.Unlock()
 331         }
 332 }
 333
 334 func (s *Server) writeBanList() error {
 335         s.banListMU.Lock()
 336         defer s.banListMU.Unlock()
 337
 338         out, err := yaml.Marshal(s.banList)
 339         if err != nil {
 340                 return err
 341         }
 342         err = ioutil.WriteFile(
 343                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 344                 out,
 345                 0666,
 346         )
 347         return err
 348 }
 349
 350 func (s *Server) writeThreadedNews() error {
 351         s.threadedNewsMux.Lock()
 352         defer s.threadedNewsMux.Unlock()
 353
 354         out, err := yaml.Marshal(s.ThreadedNews)
 355         if err != nil {
 356                 return err
 357         }
 358         err = s.FS.WriteFile(
 359                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 360                 out,
 361                 0666,
 362         )
 363         return err
 364 }
 365
 366 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 367         s.mux.Lock()
 368         defer s.mux.Unlock()
 369
 370         clientConn := &ClientConn{
 371                 ID:         &[]byte{0, 0},
 372                 Icon:       []byte{0, 0},
 373                 Flags:      []byte{0, 0},
 374                 UserName:   []byte{},
 375                 Connection: conn,
 376                 Server:     s,
 377                 Version:    []byte{},
 378                 AutoReply:  []byte{},
 379                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 380                 RemoteAddr: remoteAddr,
 381         }
 382         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 383                 FileDownload:   {},
 384                 FileUpload:     {},
 385                 FolderDownload: {},
 386                 FolderUpload:   {},
 387                 bannerDownload: {},
 388         }
 389
 390         *s.NextGuestID++
 391         ID := *s.NextGuestID
 392
 393         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 394         s.Clients[ID] = clientConn
 395
 396         return clientConn
 397 }
 398
 399 // NewUser creates a new user account entry in the server map and config file
 400 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 401         s.mux.Lock()
 402         defer s.mux.Unlock()
 403
 404         account := Account{
 405                 Login:    login,
 406                 Name:     name,
 407                 Password: hashAndSalt([]byte(password)),
 408                 Access:   access,
 409         }
 410         out, err := yaml.Marshal(&account)
 411         if err != nil {
 412                 return err
 413         }
 414         s.Accounts[login] = &account
 415
 416         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 417 }
 418
 419 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 420         s.mux.Lock()
 421         defer s.mux.Unlock()
 422
 423         // update renames the user login
 424         if login != newLogin {
 425                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 426                 if err != nil {
 427                         return err
 428                 }
 429                 s.Accounts[newLogin] = s.Accounts[login]
 430                 delete(s.Accounts, login)
 431         }
 432
 433         account := s.Accounts[newLogin]
 434         account.Access = access
 435         account.Name = name
 436         account.Password = password
 437
 438         out, err := yaml.Marshal(&account)
 439         if err != nil {
 440                 return err
 441         }
 442
 443         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 444                 return err
 445         }
 446
 447         return nil
 448 }
 449
 450 // DeleteUser deletes the user account
 451 func (s *Server) DeleteUser(login string) error {
 452         s.mux.Lock()
 453         defer s.mux.Unlock()
 454
 455         delete(s.Accounts, login)
 456
 457         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 458 }
 459
 460 func (s *Server) connectedUsers() []Field {
 461         s.mux.Lock()
 462         defer s.mux.Unlock()
 463
 464         var connectedUsers []Field
 465         for _, c := range sortedClients(s.Clients) {
 466                 user := User{
 467                         ID:    *c.ID,
 468                         Icon:  c.Icon,
 469                         Flags: c.Flags,
 470                         Name:  string(c.UserName),
 471                 }
 472                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 473         }
 474         return connectedUsers
 475 }
 476
 477 func (s *Server) loadBanList(path string) error {
 478         fh, err := os.Open(path)
 479         if err != nil {
 480                 return err
 481         }
 482         decoder := yaml.NewDecoder(fh)
 483
 484         return decoder.Decode(s.banList)
 485 }
 486
 487 // loadThreadedNews loads the threaded news data from disk
 488 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 489         fh, err := os.Open(threadedNewsPath)
 490         if err != nil {
 491                 return err
 492         }
 493         decoder := yaml.NewDecoder(fh)
 494
 495         return decoder.Decode(s.ThreadedNews)
 496 }
 497
 498 // loadAccounts loads account data from disk
 499 func (s *Server) loadAccounts(userDir string) error {
 500         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 501         if err != nil {
 502                 return err
 503         }
 504
 505         if len(matches) == 0 {
 506                 return errors.New("no user accounts found in " + userDir)
 507         }
 508
 509         for _, file := range matches {
 510                 fh, err := s.FS.Open(file)
 511                 if err != nil {
 512                         return err
 513                 }
 514
 515                 account := Account{}
 516                 decoder := yaml.NewDecoder(fh)
 517                 if err := decoder.Decode(&account); err != nil {
 518                         return err
 519                 }
 520
 521                 s.Accounts[account.Login] = &account
 522         }
 523         return nil
 524 }
 525
 526 func (s *Server) loadConfig(path string) error {
 527         fh, err := s.FS.Open(path)
 528         if err != nil {
 529                 return err
 530         }
 531
 532         decoder := yaml.NewDecoder(fh)
 533         err = decoder.Decode(s.Config)
 534         if err != nil {
 535                 return err
 536         }
 537
 538         validate := validator.New()
 539         err = validate.Struct(s.Config)
 540         if err != nil {
 541                 return err
 542         }
 543         return nil
 544 }
 545
 546 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 547 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 548         defer dontPanic(s.Logger)
 549
 550         if err := Handshake(rwc); err != nil {
 551                 return err
 552         }
 553
 554         // Create a new scanner for parsing incoming bytes into transaction tokens
 555         scanner := bufio.NewScanner(rwc)
 556         scanner.Split(transactionScanner)
 557
 558         scanner.Scan()
 559
 560         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 561         // scanner re-uses the buffer for subsequent scans.
 562         buf := make([]byte, len(scanner.Bytes()))
 563         copy(buf, scanner.Bytes())
 564
 565         var clientLogin Transaction
 566         if _, err := clientLogin.Write(buf); err != nil {
 567                 return err
 568         }
 569
 570         c := s.NewClientConn(rwc, remoteAddr)
 571
 572         // check if remoteAddr is present in the ban list
 573         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 574                 // permaban
 575                 if banUntil == nil {
 576                         s.outbox <- *NewTransaction(
 577                                 tranServerMsg,
 578                                 c.ID,
 579                                 NewField(fieldData, []byte("You are permanently banned on this server")),
 580                                 NewField(fieldChatOptions, []byte{0, 0}),
 581                         )
 582                         time.Sleep(1 * time.Second)
 583                         return nil
 584                 } else if time.Now().Before(*banUntil) {
 585                         s.outbox <- *NewTransaction(
 586                                 tranServerMsg,
 587                                 c.ID,
 588                                 NewField(fieldData, []byte("You are temporarily banned on this server")),
 589                                 NewField(fieldChatOptions, []byte{0, 0}),
 590                         )
 591                         time.Sleep(1 * time.Second)
 592                         return nil
 593                 }
 594
 595         }
 596         defer c.Disconnect()
 597
 598         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 599         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 600         c.Version = clientLogin.GetField(fieldVersion).Data
 601
 602         var login string
 603         for _, char := range encodedLogin {
 604                 login += string(rune(255 - uint(char)))
 605         }
 606         if login == "" {
 607                 login = GuestAccount
 608         }
 609
 610         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 611
 612         // If authentication fails, send error reply and close connection
 613         if !c.Authenticate(login, encodedPassword) {
 614                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 615                 b, err := t.MarshalBinary()
 616                 if err != nil {
 617                         return err
 618                 }
 619                 if _, err := rwc.Write(b); err != nil {
 620                         return err
 621                 }
 622
 623                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 624
 625                 return nil
 626         }
 627
 628         if clientLogin.GetField(fieldUserIconID).Data != nil {
 629                 c.Icon = clientLogin.GetField(fieldUserIconID).Data
 630         }
 631
 632         c.Account = c.Server.Accounts[login]
 633
 634         if clientLogin.GetField(fieldUserName).Data != nil {
 635                 if c.Authorize(accessAnyName) {
 636                         c.UserName = clientLogin.GetField(fieldUserName).Data
 637                 } else {
 638                         c.UserName = []byte(c.Account.Name)
 639                 }
 640         }
 641
 642         if c.Authorize(accessDisconUser) {
 643                 c.Flags = []byte{0, 2}
 644         }
 645
 646         s.outbox <- c.NewReply(&clientLogin,
 647                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 648                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 649                 NewField(fieldServerName, []byte(s.Config.Name)),
 650         )
 651
 652         // Send user access privs so client UI knows how to behave
 653         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, c.Account.Access[:]))
 654
 655         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 656         // client versions.  For 1.2.3 client, we do not send tranShowAgreement.  For other client versions, we send
 657         // tranShowAgreement but with the NoServerAgreement field set to 1.
 658         if c.Authorize(accessNoAgreement) {
 659                 // If client version is nil, then the client uses the 1.2.3 login behavior
 660                 if c.Version != nil {
 661                         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldNoServerAgreement, []byte{1}))
 662                 }
 663         } else {
 664                 c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 665         }
 666
 667         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 668         // TODO: figure out a generalized solution that doesn't require playing whack-a-mole for specific client versions
 669         c.logger = c.logger.With("name", string(c.UserName))
 670         c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(c.Version); return i }()))
 671
 672         for _, t := range c.notifyOthers(
 673                 *NewTransaction(
 674                         tranNotifyChangeUser, nil,
 675                         NewField(fieldUserName, c.UserName),
 676                         NewField(fieldUserID, *c.ID),
 677                         NewField(fieldUserIconID, c.Icon),
 678                         NewField(fieldUserFlags, c.Flags),
 679                 ),
 680         ) {
 681                 c.Server.outbox <- t
 682         }
 683
 684         c.Server.Stats.ConnectionCounter += 1
 685         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 686                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 687         }
 688
 689         // Scan for new transactions and handle them as they come in.
 690         for scanner.Scan() {
 691                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 692                 // scanner re-uses the buffer for subsequent scans.
 693                 buf := make([]byte, len(scanner.Bytes()))
 694                 copy(buf, scanner.Bytes())
 695
 696                 var t Transaction
 697                 if _, err := t.Write(buf); err != nil {
 698                         return err
 699                 }
 700
 701                 if err := c.handleTransaction(t); err != nil {
 702                         c.logger.Errorw("Error handling transaction", "err", err)
 703                 }
 704         }
 705         return nil
 706 }
 707
 708 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 709         s.PrivateChatsMu.Lock()
 710         defer s.PrivateChatsMu.Unlock()
 711
 712         randID := make([]byte, 4)
 713         rand.Read(randID)
 714         data := binary.BigEndian.Uint32(randID[:])
 715
 716         s.PrivateChats[data] = &PrivateChat{
 717                 ClientConn: make(map[uint16]*ClientConn),
 718         }
 719         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 720
 721         return randID
 722 }
 723
 724 const dlFldrActionSendFile = 1
 725 const dlFldrActionResumeFile = 2
 726 const dlFldrActionNextFile = 3
 727
 728 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 729 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 730         defer dontPanic(s.Logger)
 731
 732         txBuf := make([]byte, 16)
 733         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 734                 return err
 735         }
 736
 737         var t transfer
 738         if _, err := t.Write(txBuf); err != nil {
 739                 return err
 740         }
 741
 742         defer func() {
 743                 s.mux.Lock()
 744                 delete(s.fileTransfers, t.ReferenceNumber)
 745                 s.mux.Unlock()
 746
 747                 // Wait a few seconds before closing the connection: this is a workaround for problems
 748                 // observed with Windows clients where the client must initiate close of the TCP connection before
 749                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 750                 time.Sleep(3 * time.Second)
 751         }()
 752
 753         s.mux.Lock()
 754         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 755         s.mux.Unlock()
 756         if !ok {
 757                 return errors.New("invalid transaction ID")
 758         }
 759
 760         defer func() {
 761                 fileTransfer.ClientConn.transfersMU.Lock()
 762                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 763                 fileTransfer.ClientConn.transfersMU.Unlock()
 764         }()
 765
 766         rLogger := s.Logger.With(
 767                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 768                 "login", fileTransfer.ClientConn.Account.Login,
 769                 "name", string(fileTransfer.ClientConn.UserName),
 770         )
 771
 772         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 773         if err != nil {
 774                 return err
 775         }
 776
 777         switch fileTransfer.Type {
 778         case bannerDownload:
 779                 if err := s.bannerDownload(rwc); err != nil {
 780                         return err
 781                 }
 782         case FileDownload:
 783                 s.Stats.DownloadCounter += 1
 784                 s.Stats.DownloadsInProgress += 1
 785                 defer func() {
 786                         s.Stats.DownloadsInProgress -= 1
 787                 }()
 788
 789                 var dataOffset int64
 790                 if fileTransfer.fileResumeData != nil {
 791                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 792                 }
 793
 794                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 795                 if err != nil {
 796                         return err
 797                 }
 798
 799                 rLogger.Infow("File download started", "filePath", fullPath)
 800
 801                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 802                 if fileTransfer.options == nil {
 803                         // Start by sending flat file object to client
 804                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 805                                 return err
 806                         }
 807                 }
 808
 809                 file, err := fw.dataForkReader()
 810                 if err != nil {
 811                         return err
 812                 }
 813
 814                 br := bufio.NewReader(file)
 815                 if _, err := br.Discard(int(dataOffset)); err != nil {
 816                         return err
 817                 }
 818
 819                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 820                         return err
 821                 }
 822
 823                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 824                 if fileTransfer.fileResumeData == nil {
 825                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 826                         if err != nil {
 827                                 return err
 828                         }
 829                 }
 830
 831                 rFile, err := fw.rsrcForkFile()
 832                 if err != nil {
 833                         return nil
 834                 }
 835
 836                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 837                         return err
 838                 }
 839
 840         case FileUpload:
 841                 s.Stats.UploadCounter += 1
 842                 s.Stats.UploadsInProgress += 1
 843                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 844
 845                 var file *os.File
 846
 847                 // A file upload has three possible cases:
 848                 // 1) Upload a new file
 849                 // 2) Resume a partially transferred file
 850                 // 3) Replace a fully uploaded file
 851                 //  We have to infer which case applies by inspecting what is already on the filesystem
 852
 853                 // 1) Check for existing file:
 854                 _, err = os.Stat(fullPath)
 855                 if err == nil {
 856                         return errors.New("existing file found at " + fullPath)
 857                 }
 858                 if errors.Is(err, fs.ErrNotExist) {
 859                         // If not found, open or create a new .incomplete file
 860                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 861                         if err != nil {
 862                                 return err
 863                         }
 864                 }
 865
 866                 f, err := newFileWrapper(s.FS, fullPath, 0)
 867                 if err != nil {
 868                         return err
 869                 }
 870
 871                 rLogger.Infow("File upload started", "dstFile", fullPath)
 872
 873                 rForkWriter := io.Discard
 874                 iForkWriter := io.Discard
 875                 if s.Config.PreserveResourceForks {
 876                         rForkWriter, err = f.rsrcForkWriter()
 877                         if err != nil {
 878                                 return err
 879                         }
 880
 881                         iForkWriter, err = f.infoForkWriter()
 882                         if err != nil {
 883                                 return err
 884                         }
 885                 }
 886
 887                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 888                         s.Logger.Error(err)
 889                 }
 890
 891                 if err := file.Close(); err != nil {
 892                         return err
 893                 }
 894
 895                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 896                         return err
 897                 }
 898
 899                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 900
 901         case FolderDownload:
 902                 s.Stats.DownloadCounter += 1
 903                 s.Stats.DownloadsInProgress += 1
 904                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 905
 906                 // Folder Download flow:
 907                 // 1. Get filePath from the transfer
 908                 // 2. Iterate over files
 909                 // 3. For each fileWrapper:
 910                 //       Send fileWrapper header to client
 911                 // The client can reply in 3 ways:
 912                 //
 913                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 914                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 915                 //
 916                 // 2. If download of a fileWrapper is to be resumed:
 917                 //              client sends:
 918                 //                      []byte{0x00, 0x02} // download folder action
 919                 //                      [2]byte // Resume data size
 920                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 921                 //
 922                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 923                 //
 924                 // When download is requested (case 2 or 3), server replies with:
 925                 //                      [4]byte - fileWrapper size
 926                 //                      []byte  - Flattened File Object
 927                 //
 928                 // After every fileWrapper download, client could request next fileWrapper with:
 929                 //                      []byte{0x00, 0x03}
 930                 //
 931                 // This notifies the server to send the next item header
 932
 933                 basePathLen := len(fullPath)
 934
 935                 rLogger.Infow("Start folder download", "path", fullPath)
 936
 937                 nextAction := make([]byte, 2)
 938                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 939                         return err
 940                 }
 941
 942                 i := 0
 943                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 944                         s.Stats.DownloadCounter += 1
 945                         i += 1
 946
 947                         if err != nil {
 948                                 return err
 949                         }
 950
 951                         // skip dot files
 952                         if strings.HasPrefix(info.Name(), ".") {
 953                                 return nil
 954                         }
 955
 956                         hlFile, err := newFileWrapper(s.FS, path, 0)
 957                         if err != nil {
 958                                 return err
 959                         }
 960
 961                         subPath := path[basePathLen+1:]
 962                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 963
 964                         if i == 1 {
 965                                 return nil
 966                         }
 967
 968                         fileHeader := NewFileHeader(subPath, info.IsDir())
 969
 970                         // Send the fileWrapper header to client
 971                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 972                                 s.Logger.Errorf("error sending file header: %v", err)
 973                                 return err
 974                         }
 975
 976                         // Read the client's Next Action request
 977                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 978                                 return err
 979                         }
 980
 981                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 982
 983                         var dataOffset int64
 984
 985                         switch nextAction[1] {
 986                         case dlFldrActionResumeFile:
 987                                 // get size of resumeData
 988                                 resumeDataByteLen := make([]byte, 2)
 989                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 990                                         return err
 991                                 }
 992
 993                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 994                                 resumeDataBytes := make([]byte, resumeDataLen)
 995                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 996                                         return err
 997                                 }
 998
 999                                 var frd FileResumeData
1000                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1001                                         return err
1002                                 }
1003                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1004                         case dlFldrActionNextFile:
1005                                 // client asked to skip this file
1006                                 return nil
1007                         }
1008
1009                         if info.IsDir() {
1010                                 return nil
1011                         }
1012
1013                         rLogger.Infow("File download started",
1014                                 "fileName", info.Name(),
1015                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1016                         )
1017
1018                         // Send file size to client
1019                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1020                                 s.Logger.Error(err)
1021                                 return err
1022                         }
1023
1024                         // Send ffo bytes to client
1025                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1026                                 s.Logger.Error(err)
1027                                 return err
1028                         }
1029
1030                         file, err := s.FS.Open(path)
1031                         if err != nil {
1032                                 return err
1033                         }
1034
1035                         // wr := bufio.NewWriterSize(rwc, 1460)
1036                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1037                                 return err
1038                         }
1039
1040                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1041                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1042                                 if err != nil {
1043                                         return err
1044                                 }
1045
1046                                 rFile, err := hlFile.rsrcForkFile()
1047                                 if err != nil {
1048                                         return err
1049                                 }
1050
1051                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1052                                         return err
1053                                 }
1054                         }
1055
1056                         // Read the client's Next Action request.  This is always 3, I think?
1057                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1058                                 return err
1059                         }
1060
1061                         return nil
1062                 })
1063
1064                 if err != nil {
1065                         return err
1066                 }
1067
1068         case FolderUpload:
1069                 s.Stats.UploadCounter += 1
1070                 s.Stats.UploadsInProgress += 1
1071                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1072                 rLogger.Infow(
1073                         "Folder upload started",
1074                         "dstPath", fullPath,
1075                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1076                         "FolderItemCount", fileTransfer.FolderItemCount,
1077                 )
1078
1079                 // Check if the target folder exists.  If not, create it.
1080                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1081                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1082                                 return err
1083                         }
1084                 }
1085
1086                 // Begin the folder upload flow by sending the "next file action" to client
1087                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1088                         return err
1089                 }
1090
1091                 fileSize := make([]byte, 4)
1092
1093                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1094                         s.Stats.UploadCounter += 1
1095
1096                         var fu folderUpload
1097                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1098                                 return err
1099                         }
1100                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1101                                 return err
1102                         }
1103                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1104                                 return err
1105                         }
1106
1107                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1108
1109                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1110                                 return err
1111                         }
1112
1113                         rLogger.Infow(
1114                                 "Folder upload continued",
1115                                 "FormattedPath", fu.FormattedPath(),
1116                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1117                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1118                         )
1119
1120                         if fu.IsFolder == [2]byte{0, 1} {
1121                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1122                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1123                                                 return err
1124                                         }
1125                                 }
1126
1127                                 // Tell client to send next file
1128                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1129                                         return err
1130                                 }
1131                         } else {
1132                                 nextAction := dlFldrActionSendFile
1133
1134                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1135                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1136                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1137                                         return err
1138                                 }
1139                                 if err == nil {
1140                                         nextAction = dlFldrActionNextFile
1141                                 }
1142
1143                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1144                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1145                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1146                                         return err
1147                                 }
1148                                 if err == nil {
1149                                         nextAction = dlFldrActionResumeFile
1150                                 }
1151
1152                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1153                                         return err
1154                                 }
1155
1156                                 switch nextAction {
1157                                 case dlFldrActionNextFile:
1158                                         continue
1159                                 case dlFldrActionResumeFile:
1160                                         offset := make([]byte, 4)
1161                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1162
1163                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1164                                         if err != nil {
1165                                                 return err
1166                                         }
1167
1168                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1169
1170                                         b, _ := fileResumeData.BinaryMarshal()
1171
1172                                         bs := make([]byte, 2)
1173                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1174
1175                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1176                                                 return err
1177                                         }
1178
1179                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1180                                                 return err
1181                                         }
1182
1183                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1184                                                 s.Logger.Error(err)
1185                                         }
1186
1187                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1188                                         if err != nil {
1189                                                 return err
1190                                         }
1191
1192                                 case dlFldrActionSendFile:
1193                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1194                                                 return err
1195                                         }
1196
1197                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1198
1199                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1200                                         if err != nil {
1201                                                 return err
1202                                         }
1203
1204                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1205
1206                                         incWriter, err := hlFile.incFileWriter()
1207                                         if err != nil {
1208                                                 return err
1209                                         }
1210
1211                                         rForkWriter := io.Discard
1212                                         iForkWriter := io.Discard
1213                                         if s.Config.PreserveResourceForks {
1214                                                 iForkWriter, err = hlFile.infoForkWriter()
1215                                                 if err != nil {
1216                                                         return err
1217                                                 }
1218
1219                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1220                                                 if err != nil {
1221                                                         return err
1222                                                 }
1223                                         }
1224                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1225                                                 return err
1226                                         }
1227
1228                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1229                                                 return err
1230                                         }
1231                                 }
1232
1233                                 // Tell client to send next fileWrapper
1234                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1235                                         return err
1236                                 }
1237                         }
1238                 }
1239                 rLogger.Infof("Folder upload complete")
1240         }
1241
1242         return nil
1243 }