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         "strings"
  22         "sync"
  23         "time"
  24 )
  25
  26 type contextKey string
  27
  28 var contextKeyReq = contextKey("req")
  29
  30 type requestCtx struct {
  31         remoteAddr string
  32         login      string
  33         name       string
  34 }
  35
  36 const (
  37         userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
  38         idleCheckInterval      = 10  // time in seconds to check for idle users
  39         trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
  40 )
  41
  42 var nostalgiaVersion = []byte{0, 0, 2, 0x2c} // version ID used by the Nostalgia client
  43
  44 type Server struct {
  45         Port          int
  46         Accounts      map[string]*Account
  47         Agreement     []byte
  48         Clients       map[uint16]*ClientConn
  49         fileTransfers map[[4]byte]*FileTransfer
  50
  51         Config    *Config
  52         ConfigDir string
  53         Logger    *zap.SugaredLogger
  54
  55         PrivateChatsMu sync.Mutex
  56         PrivateChats   map[uint32]*PrivateChat
  57
  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         threadedNewsMux sync.Mutex
  68         ThreadedNews    *ThreadedNews
  69
  70         flatNewsMux sync.Mutex
  71         FlatNews    []byte
  72
  73         banListMU sync.Mutex
  74         banList   map[string]*time.Time
  75 }
  76
  77 type PrivateChat struct {
  78         Subject    string
  79         ClientConn map[uint16]*ClientConn
  80 }
  81
  82 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  83         s.Logger.Infow("Hotline server started",
  84                 "version", VERSION,
  85                 "API port", fmt.Sprintf(":%v", s.Port),
  86                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  87         )
  88
  89         var wg sync.WaitGroup
  90
  91         wg.Add(1)
  92         go func() {
  93                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
  94                 if err != nil {
  95                         s.Logger.Fatal(err)
  96                 }
  97
  98                 s.Logger.Fatal(s.Serve(ctx, ln))
  99         }()
 100
 101         wg.Add(1)
 102         go func() {
 103                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
 104                 if err != nil {
 105                         s.Logger.Fatal(err)
 106
 107                 }
 108
 109                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 110         }()
 111
 112         wg.Wait()
 113
 114         return nil
 115 }
 116
 117 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 118         for {
 119                 conn, err := ln.Accept()
 120                 if err != nil {
 121                         return err
 122                 }
 123
 124                 go func() {
 125                         defer func() { _ = conn.Close() }()
 126
 127                         err = s.handleFileTransfer(
 128                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 129                                         remoteAddr: conn.RemoteAddr().String(),
 130                                 }),
 131                                 conn,
 132                         )
 133
 134                         if err != nil {
 135                                 s.Logger.Errorw("file transfer error", "reason", err)
 136                         }
 137                 }()
 138         }
 139 }
 140
 141 func (s *Server) sendTransaction(t Transaction) error {
 142         clientID, err := byteToInt(*t.clientID)
 143         if err != nil {
 144                 return err
 145         }
 146
 147         s.mux.Lock()
 148         client := s.Clients[uint16(clientID)]
 149         if client == nil {
 150                 return fmt.Errorf("invalid client id %v", *t.clientID)
 151         }
 152
 153         s.mux.Unlock()
 154
 155         b, err := t.MarshalBinary()
 156         if err != nil {
 157                 return err
 158         }
 159
 160         if _, err := client.Connection.Write(b); err != nil {
 161                 return err
 162         }
 163
 164         return nil
 165 }
 166
 167 func (s *Server) processOutbox() {
 168         for {
 169                 t := <-s.outbox
 170                 go func() {
 171                         if err := s.sendTransaction(t); err != nil {
 172                                 s.Logger.Errorw("error sending transaction", "err", err)
 173                         }
 174                 }()
 175         }
 176 }
 177
 178 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 179         go s.processOutbox()
 180
 181         for {
 182                 conn, err := ln.Accept()
 183                 if err != nil {
 184                         s.Logger.Errorw("error accepting connection", "err", err)
 185                 }
 186                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 187                         remoteAddr: conn.RemoteAddr().String(),
 188                 })
 189
 190                 go func() {
 191                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 192
 193                         defer conn.Close()
 194                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 195                                 if err == io.EOF {
 196                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 197                                 } else {
 198                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 199                                 }
 200                         }
 201                 }()
 202         }
 203 }
 204
 205 const (
 206         agreementFile = "Agreement.txt"
 207 )
 208
 209 // NewServer constructs a new Server from a config dir
 210 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 211         server := Server{
 212                 Port:          netPort,
 213                 Accounts:      make(map[string]*Account),
 214                 Config:        new(Config),
 215                 Clients:       make(map[uint16]*ClientConn),
 216                 fileTransfers: make(map[[4]byte]*FileTransfer),
 217                 PrivateChats:  make(map[uint32]*PrivateChat),
 218                 ConfigDir:     configDir,
 219                 Logger:        logger,
 220                 NextGuestID:   new(uint16),
 221                 outbox:        make(chan Transaction),
 222                 Stats:         &Stats{StartTime: time.Now()},
 223                 ThreadedNews:  &ThreadedNews{},
 224                 FS:            FS,
 225                 banList:       make(map[string]*time.Time),
 226         }
 227
 228         var err error
 229
 230         // generate a new random passID for tracker registration
 231         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 232                 return nil, err
 233         }
 234
 235         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 236         if err != nil {
 237                 return nil, err
 238         }
 239
 240         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 241                 return nil, err
 242         }
 243
 244         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 245         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 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.Debugw("Sent Tracker registration", "addr", t)
 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) writeBanList() error {
 332         s.banListMU.Lock()
 333         defer s.banListMU.Unlock()
 334
 335         out, err := yaml.Marshal(s.banList)
 336         if err != nil {
 337                 return err
 338         }
 339         err = ioutil.WriteFile(
 340                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 341                 out,
 342                 0666,
 343         )
 344         return err
 345 }
 346
 347 func (s *Server) writeThreadedNews() error {
 348         s.threadedNewsMux.Lock()
 349         defer s.threadedNewsMux.Unlock()
 350
 351         out, err := yaml.Marshal(s.ThreadedNews)
 352         if err != nil {
 353                 return err
 354         }
 355         err = s.FS.WriteFile(
 356                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 357                 out,
 358                 0666,
 359         )
 360         return err
 361 }
 362
 363 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 364         s.mux.Lock()
 365         defer s.mux.Unlock()
 366
 367         clientConn := &ClientConn{
 368                 ID:         &[]byte{0, 0},
 369                 Icon:       []byte{0, 0},
 370                 Flags:      []byte{0, 0},
 371                 UserName:   []byte{},
 372                 Connection: conn,
 373                 Server:     s,
 374                 Version:    []byte{},
 375                 AutoReply:  []byte{},
 376                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 377                 Agreed:     false,
 378                 RemoteAddr: remoteAddr,
 379         }
 380         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 381                 FileDownload:   {},
 382                 FileUpload:     {},
 383                 FolderDownload: {},
 384                 FolderUpload:   {},
 385                 bannerDownload: {},
 386         }
 387
 388         *s.NextGuestID++
 389         ID := *s.NextGuestID
 390
 391         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 392         s.Clients[ID] = clientConn
 393
 394         return clientConn
 395 }
 396
 397 // NewUser creates a new user account entry in the server map and config file
 398 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 399         s.mux.Lock()
 400         defer s.mux.Unlock()
 401
 402         account := Account{
 403                 Login:    login,
 404                 Name:     name,
 405                 Password: hashAndSalt([]byte(password)),
 406                 Access:   access,
 407         }
 408         out, err := yaml.Marshal(&account)
 409         if err != nil {
 410                 return err
 411         }
 412         s.Accounts[login] = &account
 413
 414         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 415 }
 416
 417 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 418         s.mux.Lock()
 419         defer s.mux.Unlock()
 420
 421         // update renames the user login
 422         if login != newLogin {
 423                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 424                 if err != nil {
 425                         return err
 426                 }
 427                 s.Accounts[newLogin] = s.Accounts[login]
 428                 delete(s.Accounts, login)
 429         }
 430
 431         account := s.Accounts[newLogin]
 432         account.Access = access
 433         account.Name = name
 434         account.Password = password
 435
 436         out, err := yaml.Marshal(&account)
 437         if err != nil {
 438                 return err
 439         }
 440
 441         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 442                 return err
 443         }
 444
 445         return nil
 446 }
 447
 448 // DeleteUser deletes the user account
 449 func (s *Server) DeleteUser(login string) error {
 450         s.mux.Lock()
 451         defer s.mux.Unlock()
 452
 453         delete(s.Accounts, login)
 454
 455         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 456 }
 457
 458 func (s *Server) connectedUsers() []Field {
 459         s.mux.Lock()
 460         defer s.mux.Unlock()
 461
 462         var connectedUsers []Field
 463         for _, c := range sortedClients(s.Clients) {
 464                 if !c.Agreed {
 465                         continue
 466                 }
 467                 user := User{
 468                         ID:    *c.ID,
 469                         Icon:  c.Icon,
 470                         Flags: c.Flags,
 471                         Name:  string(c.UserName),
 472                 }
 473                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 474         }
 475         return connectedUsers
 476 }
 477
 478 func (s *Server) loadBanList(path string) error {
 479         fh, err := os.Open(path)
 480         if err != nil {
 481                 return err
 482         }
 483         decoder := yaml.NewDecoder(fh)
 484
 485         return decoder.Decode(s.banList)
 486 }
 487
 488 // loadThreadedNews loads the threaded news data from disk
 489 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 490         fh, err := os.Open(threadedNewsPath)
 491         if err != nil {
 492                 return err
 493         }
 494         decoder := yaml.NewDecoder(fh)
 495
 496         return decoder.Decode(s.ThreadedNews)
 497 }
 498
 499 // loadAccounts loads account data from disk
 500 func (s *Server) loadAccounts(userDir string) error {
 501         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 502         if err != nil {
 503                 return err
 504         }
 505
 506         if len(matches) == 0 {
 507                 return errors.New("no user accounts found in " + userDir)
 508         }
 509
 510         for _, file := range matches {
 511                 fh, err := s.FS.Open(file)
 512                 if err != nil {
 513                         return err
 514                 }
 515
 516                 account := Account{}
 517                 decoder := yaml.NewDecoder(fh)
 518                 if err := decoder.Decode(&account); err != nil {
 519                         return err
 520                 }
 521
 522                 s.Accounts[account.Login] = &account
 523         }
 524         return nil
 525 }
 526
 527 func (s *Server) loadConfig(path string) error {
 528         fh, err := s.FS.Open(path)
 529         if err != nil {
 530                 return err
 531         }
 532
 533         decoder := yaml.NewDecoder(fh)
 534         err = decoder.Decode(s.Config)
 535         if err != nil {
 536                 return err
 537         }
 538
 539         validate := validator.New()
 540         err = validate.Struct(s.Config)
 541         if err != nil {
 542                 return err
 543         }
 544         return nil
 545 }
 546
 547 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 548 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 549         defer dontPanic(s.Logger)
 550
 551         if err := Handshake(rwc); err != nil {
 552                 return err
 553         }
 554
 555         // Create a new scanner for parsing incoming bytes into transaction tokens
 556         scanner := bufio.NewScanner(rwc)
 557         scanner.Split(transactionScanner)
 558
 559         scanner.Scan()
 560
 561         var clientLogin Transaction
 562         if _, err := clientLogin.Write(scanner.Bytes()); err != nil {
 563                 return err
 564         }
 565
 566         c := s.NewClientConn(rwc, remoteAddr)
 567
 568         // check if remoteAddr is present in the ban list
 569         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 570                 // permaban
 571                 if banUntil == nil {
 572                         s.outbox <- *NewTransaction(
 573                                 tranServerMsg,
 574                                 c.ID,
 575                                 NewField(fieldData, []byte("You are permanently banned on this server")),
 576                                 NewField(fieldChatOptions, []byte{0, 0}),
 577                         )
 578                         time.Sleep(1 * time.Second)
 579                         return nil
 580                 } else if time.Now().Before(*banUntil) {
 581                         s.outbox <- *NewTransaction(
 582                                 tranServerMsg,
 583                                 c.ID,
 584                                 NewField(fieldData, []byte("You are temporarily banned on this server")),
 585                                 NewField(fieldChatOptions, []byte{0, 0}),
 586                         )
 587                         time.Sleep(1 * time.Second)
 588                         return nil
 589                 }
 590
 591         }
 592         defer c.Disconnect()
 593
 594         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 595         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 596         c.Version = clientLogin.GetField(fieldVersion).Data
 597
 598         var login string
 599         for _, char := range encodedLogin {
 600                 login += string(rune(255 - uint(char)))
 601         }
 602         if login == "" {
 603                 login = GuestAccount
 604         }
 605
 606         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 607
 608         // If authentication fails, send error reply and close connection
 609         if !c.Authenticate(login, encodedPassword) {
 610                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 611                 b, err := t.MarshalBinary()
 612                 if err != nil {
 613                         return err
 614                 }
 615                 if _, err := rwc.Write(b); err != nil {
 616                         return err
 617                 }
 618
 619                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 620
 621                 return nil
 622         }
 623
 624         if clientLogin.GetField(fieldUserIconID).Data != nil {
 625                 c.Icon = clientLogin.GetField(fieldUserIconID).Data
 626         }
 627
 628         c.Account = c.Server.Accounts[login]
 629
 630         if clientLogin.GetField(fieldUserName).Data != nil {
 631                 if c.Authorize(accessAnyName) {
 632                         c.UserName = clientLogin.GetField(fieldUserName).Data
 633                 } else {
 634                         c.UserName = []byte(c.Account.Name)
 635                 }
 636         }
 637
 638         if c.Authorize(accessDisconUser) {
 639                 c.Flags = []byte{0, 2}
 640         }
 641
 642         s.outbox <- c.NewReply(&clientLogin,
 643                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 644                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 645                 NewField(fieldServerName, []byte(s.Config.Name)),
 646         )
 647
 648         // Send user access privs so client UI knows how to behave
 649         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, c.Account.Access[:]))
 650
 651         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 652         // client versions.  For 1.2.3 client, we do not send tranShowAgreement.  For other client versions, we send
 653         // tranShowAgreement but with the NoServerAgreement field set to 1.
 654         if c.Authorize(accessNoAgreement) {
 655                 // If client version is nil, then the client uses the 1.2.3 login behavior
 656                 if c.Version != nil {
 657                         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldNoServerAgreement, []byte{1}))
 658                 }
 659         } else {
 660                 c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 661         }
 662
 663         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 664         if c.Version == nil || bytes.Equal(c.Version, nostalgiaVersion) {
 665                 c.Agreed = true
 666                 c.logger = c.logger.With("name", string(c.UserName))
 667                 c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(c.Version); return i }()))
 668
 669                 for _, t := range c.notifyOthers(
 670                         *NewTransaction(
 671                                 tranNotifyChangeUser, nil,
 672                                 NewField(fieldUserName, c.UserName),
 673                                 NewField(fieldUserID, *c.ID),
 674                                 NewField(fieldUserIconID, c.Icon),
 675                                 NewField(fieldUserFlags, c.Flags),
 676                         ),
 677                 ) {
 678                         c.Server.outbox <- t
 679                 }
 680         }
 681
 682         c.Server.Stats.LoginCount += 1
 683
 684         // Scan for new transactions and handle them as they come in.
 685         for scanner.Scan() {
 686                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 687                 // scanner re-uses the buffer for subsequent scans.
 688                 buf := make([]byte, len(scanner.Bytes()))
 689                 copy(buf, scanner.Bytes())
 690
 691                 var t Transaction
 692                 if _, err := t.Write(buf); err != nil {
 693                         return err
 694                 }
 695
 696                 if err := c.handleTransaction(t); err != nil {
 697                         c.logger.Errorw("Error handling transaction", "err", err)
 698                 }
 699         }
 700         return nil
 701 }
 702
 703 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 704         s.PrivateChatsMu.Lock()
 705         defer s.PrivateChatsMu.Unlock()
 706
 707         randID := make([]byte, 4)
 708         rand.Read(randID)
 709         data := binary.BigEndian.Uint32(randID[:])
 710
 711         s.PrivateChats[data] = &PrivateChat{
 712                 ClientConn: make(map[uint16]*ClientConn),
 713         }
 714         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 715
 716         return randID
 717 }
 718
 719 const dlFldrActionSendFile = 1
 720 const dlFldrActionResumeFile = 2
 721 const dlFldrActionNextFile = 3
 722
 723 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 724 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 725         defer dontPanic(s.Logger)
 726
 727         txBuf := make([]byte, 16)
 728         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 729                 return err
 730         }
 731
 732         var t transfer
 733         if _, err := t.Write(txBuf); err != nil {
 734                 return err
 735         }
 736
 737         defer func() {
 738                 s.mux.Lock()
 739                 delete(s.fileTransfers, t.ReferenceNumber)
 740                 s.mux.Unlock()
 741
 742         }()
 743
 744         s.mux.Lock()
 745         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 746         s.mux.Unlock()
 747         if !ok {
 748                 return errors.New("invalid transaction ID")
 749         }
 750
 751         defer func() {
 752                 fileTransfer.ClientConn.transfersMU.Lock()
 753                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 754                 fileTransfer.ClientConn.transfersMU.Unlock()
 755         }()
 756
 757         rLogger := s.Logger.With(
 758                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 759                 "login", fileTransfer.ClientConn.Account.Login,
 760                 "name", string(fileTransfer.ClientConn.UserName),
 761         )
 762
 763         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 764         if err != nil {
 765                 return err
 766         }
 767
 768         switch fileTransfer.Type {
 769         case bannerDownload:
 770                 if err := s.bannerDownload(rwc); err != nil {
 771                         return err
 772                 }
 773         case FileDownload:
 774                 s.Stats.DownloadCounter += 1
 775
 776                 var dataOffset int64
 777                 if fileTransfer.fileResumeData != nil {
 778                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 779                 }
 780
 781                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 782                 if err != nil {
 783                         return err
 784                 }
 785
 786                 rLogger.Infow("File download started", "filePath", fullPath)
 787
 788                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 789                 if fileTransfer.options == nil {
 790                         // Start by sending flat file object to client
 791                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 792                                 return err
 793                         }
 794                 }
 795
 796                 file, err := fw.dataForkReader()
 797                 if err != nil {
 798                         return err
 799                 }
 800
 801                 br := bufio.NewReader(file)
 802                 if _, err := br.Discard(int(dataOffset)); err != nil {
 803                         return err
 804                 }
 805
 806                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 807                         return err
 808                 }
 809
 810                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 811                 if fileTransfer.fileResumeData == nil {
 812                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 813                         if err != nil {
 814                                 return err
 815                         }
 816                 }
 817
 818                 rFile, err := fw.rsrcForkFile()
 819                 if err != nil {
 820                         return nil
 821                 }
 822
 823                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 824                         return err
 825                 }
 826
 827         case FileUpload:
 828                 s.Stats.UploadCounter += 1
 829
 830                 var file *os.File
 831
 832                 // A file upload has three possible cases:
 833                 // 1) Upload a new file
 834                 // 2) Resume a partially transferred file
 835                 // 3) Replace a fully uploaded file
 836                 //  We have to infer which case applies by inspecting what is already on the filesystem
 837
 838                 // 1) Check for existing file:
 839                 _, err = os.Stat(fullPath)
 840                 if err == nil {
 841                         return errors.New("existing file found at " + fullPath)
 842                 }
 843                 if errors.Is(err, fs.ErrNotExist) {
 844                         // If not found, open or create a new .incomplete file
 845                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 846                         if err != nil {
 847                                 return err
 848                         }
 849                 }
 850
 851                 f, err := newFileWrapper(s.FS, fullPath, 0)
 852                 if err != nil {
 853                         return err
 854                 }
 855
 856                 rLogger.Infow("File upload started", "dstFile", fullPath)
 857
 858                 rForkWriter := io.Discard
 859                 iForkWriter := io.Discard
 860                 if s.Config.PreserveResourceForks {
 861                         rForkWriter, err = f.rsrcForkWriter()
 862                         if err != nil {
 863                                 return err
 864                         }
 865
 866                         iForkWriter, err = f.infoForkWriter()
 867                         if err != nil {
 868                                 return err
 869                         }
 870                 }
 871
 872                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 873                         s.Logger.Error(err)
 874                 }
 875
 876                 if err := file.Close(); err != nil {
 877                         return err
 878                 }
 879
 880                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 881                         return err
 882                 }
 883
 884                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 885         case FolderDownload:
 886                 // Folder Download flow:
 887                 // 1. Get filePath from the transfer
 888                 // 2. Iterate over files
 889                 // 3. For each fileWrapper:
 890                 //       Send fileWrapper header to client
 891                 // The client can reply in 3 ways:
 892                 //
 893                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 894                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 895                 //
 896                 // 2. If download of a fileWrapper is to be resumed:
 897                 //              client sends:
 898                 //                      []byte{0x00, 0x02} // download folder action
 899                 //                      [2]byte // Resume data size
 900                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 901                 //
 902                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 903                 //
 904                 // When download is requested (case 2 or 3), server replies with:
 905                 //                      [4]byte - fileWrapper size
 906                 //                      []byte  - Flattened File Object
 907                 //
 908                 // After every fileWrapper download, client could request next fileWrapper with:
 909                 //                      []byte{0x00, 0x03}
 910                 //
 911                 // This notifies the server to send the next item header
 912
 913                 basePathLen := len(fullPath)
 914
 915                 rLogger.Infow("Start folder download", "path", fullPath)
 916
 917                 nextAction := make([]byte, 2)
 918                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 919                         return err
 920                 }
 921
 922                 i := 0
 923                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 924                         s.Stats.DownloadCounter += 1
 925                         i += 1
 926
 927                         if err != nil {
 928                                 return err
 929                         }
 930
 931                         // skip dot files
 932                         if strings.HasPrefix(info.Name(), ".") {
 933                                 return nil
 934                         }
 935
 936                         hlFile, err := newFileWrapper(s.FS, path, 0)
 937                         if err != nil {
 938                                 return err
 939                         }
 940
 941                         subPath := path[basePathLen+1:]
 942                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 943
 944                         if i == 1 {
 945                                 return nil
 946                         }
 947
 948                         fileHeader := NewFileHeader(subPath, info.IsDir())
 949
 950                         // Send the fileWrapper header to client
 951                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 952                                 s.Logger.Errorf("error sending file header: %v", err)
 953                                 return err
 954                         }
 955
 956                         // Read the client's Next Action request
 957                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 958                                 return err
 959                         }
 960
 961                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 962
 963                         var dataOffset int64
 964
 965                         switch nextAction[1] {
 966                         case dlFldrActionResumeFile:
 967                                 // get size of resumeData
 968                                 resumeDataByteLen := make([]byte, 2)
 969                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
 970                                         return err
 971                                 }
 972
 973                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
 974                                 resumeDataBytes := make([]byte, resumeDataLen)
 975                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
 976                                         return err
 977                                 }
 978
 979                                 var frd FileResumeData
 980                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 981                                         return err
 982                                 }
 983                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 984                         case dlFldrActionNextFile:
 985                                 // client asked to skip this file
 986                                 return nil
 987                         }
 988
 989                         if info.IsDir() {
 990                                 return nil
 991                         }
 992
 993                         rLogger.Infow("File download started",
 994                                 "fileName", info.Name(),
 995                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
 996                         )
 997
 998                         // Send file size to client
 999                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1000                                 s.Logger.Error(err)
1001                                 return err
1002                         }
1003
1004                         // Send ffo bytes to client
1005                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1006                                 s.Logger.Error(err)
1007                                 return err
1008                         }
1009
1010                         file, err := s.FS.Open(path)
1011                         if err != nil {
1012                                 return err
1013                         }
1014
1015                         // wr := bufio.NewWriterSize(rwc, 1460)
1016                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1017                                 return err
1018                         }
1019
1020                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1021                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1022                                 if err != nil {
1023                                         return err
1024                                 }
1025
1026                                 rFile, err := hlFile.rsrcForkFile()
1027                                 if err != nil {
1028                                         return err
1029                                 }
1030
1031                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1032                                         return err
1033                                 }
1034                         }
1035
1036                         // Read the client's Next Action request.  This is always 3, I think?
1037                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1038                                 return err
1039                         }
1040
1041                         return nil
1042                 })
1043
1044                 if err != nil {
1045                         return err
1046                 }
1047
1048         case FolderUpload:
1049                 rLogger.Infow(
1050                         "Folder upload started",
1051                         "dstPath", fullPath,
1052                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1053                         "FolderItemCount", fileTransfer.FolderItemCount,
1054                 )
1055
1056                 // Check if the target folder exists.  If not, create it.
1057                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1058                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1059                                 return err
1060                         }
1061                 }
1062
1063                 // Begin the folder upload flow by sending the "next file action" to client
1064                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1065                         return err
1066                 }
1067
1068                 fileSize := make([]byte, 4)
1069
1070                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1071                         s.Stats.UploadCounter += 1
1072
1073                         var fu folderUpload
1074                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1075                                 return err
1076                         }
1077                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1078                                 return err
1079                         }
1080                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1081                                 return err
1082                         }
1083
1084                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1085
1086                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1087                                 return err
1088                         }
1089
1090                         rLogger.Infow(
1091                                 "Folder upload continued",
1092                                 "FormattedPath", fu.FormattedPath(),
1093                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1094                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1095                         )
1096
1097                         if fu.IsFolder == [2]byte{0, 1} {
1098                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1099                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1100                                                 return err
1101                                         }
1102                                 }
1103
1104                                 // Tell client to send next file
1105                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1106                                         return err
1107                                 }
1108                         } else {
1109                                 nextAction := dlFldrActionSendFile
1110
1111                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1112                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1113                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1114                                         return err
1115                                 }
1116                                 if err == nil {
1117                                         nextAction = dlFldrActionNextFile
1118                                 }
1119
1120                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1121                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1122                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1123                                         return err
1124                                 }
1125                                 if err == nil {
1126                                         nextAction = dlFldrActionResumeFile
1127                                 }
1128
1129                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1130                                         return err
1131                                 }
1132
1133                                 switch nextAction {
1134                                 case dlFldrActionNextFile:
1135                                         continue
1136                                 case dlFldrActionResumeFile:
1137                                         offset := make([]byte, 4)
1138                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1139
1140                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1141                                         if err != nil {
1142                                                 return err
1143                                         }
1144
1145                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1146
1147                                         b, _ := fileResumeData.BinaryMarshal()
1148
1149                                         bs := make([]byte, 2)
1150                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1151
1152                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1153                                                 return err
1154                                         }
1155
1156                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1157                                                 return err
1158                                         }
1159
1160                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1161                                                 s.Logger.Error(err)
1162                                         }
1163
1164                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1165                                         if err != nil {
1166                                                 return err
1167                                         }
1168
1169                                 case dlFldrActionSendFile:
1170                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1171                                                 return err
1172                                         }
1173
1174                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1175
1176                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1177                                         if err != nil {
1178                                                 return err
1179                                         }
1180
1181                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1182
1183                                         incWriter, err := hlFile.incFileWriter()
1184                                         if err != nil {
1185                                                 return err
1186                                         }
1187
1188                                         rForkWriter := io.Discard
1189                                         iForkWriter := io.Discard
1190                                         if s.Config.PreserveResourceForks {
1191                                                 iForkWriter, err = hlFile.infoForkWriter()
1192                                                 if err != nil {
1193                                                         return err
1194                                                 }
1195
1196                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1197                                                 if err != nil {
1198                                                         return err
1199                                                 }
1200                                         }
1201                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1202                                                 return err
1203                                         }
1204
1205                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1206                                                 return err
1207                                         }
1208                                 }
1209
1210                                 // Tell client to send next fileWrapper
1211                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1212                                         return err
1213                                 }
1214                         }
1215                 }
1216                 rLogger.Infof("Folder upload complete")
1217         }
1218
1219         return nil
1220 }