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 var nostalgiaVersion = []byte{0, 0, 2, 0x2c} // version ID used by the Nostalgia client
  37 var frogblastVersion = []byte{0, 0, 0, 0xb9} // version ID used by the Frogblast 1.2.4 client
  38
  39 type Server struct {
  40         Port          int
  41         Accounts      map[string]*Account
  42         Agreement     []byte
  43         Clients       map[uint16]*ClientConn
  44         fileTransfers map[[4]byte]*FileTransfer
  45
  46         Config    *Config
  47         ConfigDir string
  48         Logger    *zap.SugaredLogger
  49
  50         PrivateChatsMu sync.Mutex
  51         PrivateChats   map[uint32]*PrivateChat
  52
  53         NextGuestID   *uint16
  54         TrackerPassID [4]byte
  55
  56         StatsMu sync.Mutex
  57         Stats   *Stats
  58
  59         FS FileStore // Storage backend to use for File storage
  60
  61         outbox chan Transaction
  62         mux    sync.Mutex
  63
  64         threadedNewsMux sync.Mutex
  65         ThreadedNews    *ThreadedNews
  66
  67         flatNewsMux sync.Mutex
  68         FlatNews    []byte
  69
  70         banListMU sync.Mutex
  71         banList   map[string]*time.Time
  72 }
  73
  74 func (s *Server) CurrentStats() Stats {
  75         s.StatsMu.Lock()
  76         defer s.StatsMu.Unlock()
  77
  78         stats := s.Stats
  79         stats.CurrentlyConnected = len(s.Clients)
  80
  81         return *stats
  82 }
  83
  84 type PrivateChat struct {
  85         Subject    string
  86         ClientConn map[uint16]*ClientConn
  87 }
  88
  89 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  90         s.Logger.Infow("Hotline server started",
  91                 "version", VERSION,
  92                 "API port", fmt.Sprintf(":%v", s.Port),
  93                 "Transfer port", fmt.Sprintf(":%v", s.Port+1),
  94         )
  95
  96         var wg sync.WaitGroup
  97
  98         wg.Add(1)
  99         go func() {
 100                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port))
 101                 if err != nil {
 102                         s.Logger.Fatal(err)
 103                 }
 104
 105                 s.Logger.Fatal(s.Serve(ctx, ln))
 106         }()
 107
 108         wg.Add(1)
 109         go func() {
 110                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", "", s.Port+1))
 111                 if err != nil {
 112                         s.Logger.Fatal(err)
 113
 114                 }
 115
 116                 s.Logger.Fatal(s.ServeFileTransfers(ctx, ln))
 117         }()
 118
 119         wg.Wait()
 120
 121         return nil
 122 }
 123
 124 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 125         for {
 126                 conn, err := ln.Accept()
 127                 if err != nil {
 128                         return err
 129                 }
 130
 131                 go func() {
 132                         defer func() { _ = conn.Close() }()
 133
 134                         err = s.handleFileTransfer(
 135                                 context.WithValue(ctx, contextKeyReq, requestCtx{
 136                                         remoteAddr: conn.RemoteAddr().String(),
 137                                 }),
 138                                 conn,
 139                         )
 140
 141                         if err != nil {
 142                                 s.Logger.Errorw("file transfer error", "reason", err)
 143                         }
 144                 }()
 145         }
 146 }
 147
 148 func (s *Server) sendTransaction(t Transaction) error {
 149         clientID, err := byteToInt(*t.clientID)
 150         if err != nil {
 151                 return err
 152         }
 153
 154         s.mux.Lock()
 155         client := s.Clients[uint16(clientID)]
 156         if client == nil {
 157                 return fmt.Errorf("invalid client id %v", *t.clientID)
 158         }
 159
 160         s.mux.Unlock()
 161
 162         b, err := t.MarshalBinary()
 163         if err != nil {
 164                 return err
 165         }
 166
 167         if _, err := client.Connection.Write(b); err != nil {
 168                 return err
 169         }
 170
 171         return nil
 172 }
 173
 174 func (s *Server) processOutbox() {
 175         for {
 176                 t := <-s.outbox
 177                 go func() {
 178                         if err := s.sendTransaction(t); err != nil {
 179                                 s.Logger.Errorw("error sending transaction", "err", err)
 180                         }
 181                 }()
 182         }
 183 }
 184
 185 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 186         go s.processOutbox()
 187
 188         for {
 189                 conn, err := ln.Accept()
 190                 if err != nil {
 191                         s.Logger.Errorw("error accepting connection", "err", err)
 192                 }
 193                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 194                         remoteAddr: conn.RemoteAddr().String(),
 195                 })
 196
 197                 go func() {
 198                         s.Logger.Infow("Connection established", "RemoteAddr", conn.RemoteAddr())
 199
 200                         defer conn.Close()
 201                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 202                                 if err == io.EOF {
 203                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 204                                 } else {
 205                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 206                                 }
 207                         }
 208                 }()
 209         }
 210 }
 211
 212 const (
 213         agreementFile = "Agreement.txt"
 214 )
 215
 216 // NewServer constructs a new Server from a config dir
 217 func NewServer(configDir string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {
 218         server := Server{
 219                 Port:          netPort,
 220                 Accounts:      make(map[string]*Account),
 221                 Config:        new(Config),
 222                 Clients:       make(map[uint16]*ClientConn),
 223                 fileTransfers: make(map[[4]byte]*FileTransfer),
 224                 PrivateChats:  make(map[uint32]*PrivateChat),
 225                 ConfigDir:     configDir,
 226                 Logger:        logger,
 227                 NextGuestID:   new(uint16),
 228                 outbox:        make(chan Transaction),
 229                 Stats:         &Stats{Since: time.Now()},
 230                 ThreadedNews:  &ThreadedNews{},
 231                 FS:            FS,
 232                 banList:       make(map[string]*time.Time),
 233         }
 234
 235         var err error
 236
 237         // generate a new random passID for tracker registration
 238         if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
 239                 return nil, err
 240         }
 241
 242         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
 243         if err != nil {
 244                 return nil, err
 245         }
 246
 247         if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
 248                 return nil, err
 249         }
 250
 251         // try to load the ban list, but ignore errors as this file may not be present or may be empty
 252         _ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
 253
 254         if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
 255                 return nil, err
 256         }
 257
 258         if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
 259                 return nil, err
 260         }
 261
 262         if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
 263                 return nil, err
 264         }
 265
 266         server.Config.FileRoot = filepath.Join(configDir, "Files")
 267
 268         *server.NextGuestID = 1
 269
 270         if server.Config.EnableTrackerRegistration {
 271                 server.Logger.Infow(
 272                         "Tracker registration enabled",
 273                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 274                         "trackers", server.Config.Trackers,
 275                 )
 276
 277                 go func() {
 278                         for {
 279                                 tr := &TrackerRegistration{
 280                                         UserCount:   server.userCount(),
 281                                         PassID:      server.TrackerPassID[:],
 282                                         Name:        server.Config.Name,
 283                                         Description: server.Config.Description,
 284                                 }
 285                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
 286                                 for _, t := range server.Config.Trackers {
 287                                         if err := register(t, tr); err != nil {
 288                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 289                                         }
 290                                         server.Logger.Debugw("Sent Tracker registration", "addr", t)
 291                                 }
 292
 293                                 time.Sleep(trackerUpdateFrequency * time.Second)
 294                         }
 295                 }()
 296         }
 297
 298         // Start Client Keepalive go routine
 299         go server.keepaliveHandler()
 300
 301         return &server, nil
 302 }
 303
 304 func (s *Server) userCount() int {
 305         s.mux.Lock()
 306         defer s.mux.Unlock()
 307
 308         return len(s.Clients)
 309 }
 310
 311 func (s *Server) keepaliveHandler() {
 312         for {
 313                 time.Sleep(idleCheckInterval * time.Second)
 314                 s.mux.Lock()
 315
 316                 for _, c := range s.Clients {
 317                         c.IdleTime += idleCheckInterval
 318                         if c.IdleTime > userIdleSeconds && !c.Idle {
 319                                 c.Idle = true
 320
 321                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 322                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 323                                 binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 324
 325                                 c.sendAll(
 326                                         tranNotifyChangeUser,
 327                                         NewField(fieldUserID, *c.ID),
 328                                         NewField(fieldUserFlags, c.Flags),
 329                                         NewField(fieldUserName, c.UserName),
 330                                         NewField(fieldUserIconID, c.Icon),
 331                                 )
 332                         }
 333                 }
 334                 s.mux.Unlock()
 335         }
 336 }
 337
 338 func (s *Server) writeBanList() error {
 339         s.banListMU.Lock()
 340         defer s.banListMU.Unlock()
 341
 342         out, err := yaml.Marshal(s.banList)
 343         if err != nil {
 344                 return err
 345         }
 346         err = ioutil.WriteFile(
 347                 filepath.Join(s.ConfigDir, "Banlist.yaml"),
 348                 out,
 349                 0666,
 350         )
 351         return err
 352 }
 353
 354 func (s *Server) writeThreadedNews() error {
 355         s.threadedNewsMux.Lock()
 356         defer s.threadedNewsMux.Unlock()
 357
 358         out, err := yaml.Marshal(s.ThreadedNews)
 359         if err != nil {
 360                 return err
 361         }
 362         err = s.FS.WriteFile(
 363                 filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
 364                 out,
 365                 0666,
 366         )
 367         return err
 368 }
 369
 370 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 371         s.mux.Lock()
 372         defer s.mux.Unlock()
 373
 374         clientConn := &ClientConn{
 375                 ID:         &[]byte{0, 0},
 376                 Icon:       []byte{0, 0},
 377                 Flags:      []byte{0, 0},
 378                 UserName:   []byte{},
 379                 Connection: conn,
 380                 Server:     s,
 381                 Version:    []byte{},
 382                 AutoReply:  []byte{},
 383                 transfers:  map[int]map[[4]byte]*FileTransfer{},
 384                 Agreed:     false,
 385                 RemoteAddr: remoteAddr,
 386         }
 387         clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
 388                 FileDownload:   {},
 389                 FileUpload:     {},
 390                 FolderDownload: {},
 391                 FolderUpload:   {},
 392                 bannerDownload: {},
 393         }
 394
 395         *s.NextGuestID++
 396         ID := *s.NextGuestID
 397
 398         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 399         s.Clients[ID] = clientConn
 400
 401         return clientConn
 402 }
 403
 404 // NewUser creates a new user account entry in the server map and config file
 405 func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
 406         s.mux.Lock()
 407         defer s.mux.Unlock()
 408
 409         account := Account{
 410                 Login:    login,
 411                 Name:     name,
 412                 Password: hashAndSalt([]byte(password)),
 413                 Access:   access,
 414         }
 415         out, err := yaml.Marshal(&account)
 416         if err != nil {
 417                 return err
 418         }
 419         s.Accounts[login] = &account
 420
 421         return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
 422 }
 423
 424 func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
 425         s.mux.Lock()
 426         defer s.mux.Unlock()
 427
 428         // update renames the user login
 429         if login != newLogin {
 430                 err := os.Rename(filepath.Join(s.ConfigDir, "Users", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
 431                 if err != nil {
 432                         return err
 433                 }
 434                 s.Accounts[newLogin] = s.Accounts[login]
 435                 delete(s.Accounts, login)
 436         }
 437
 438         account := s.Accounts[newLogin]
 439         account.Access = access
 440         account.Name = name
 441         account.Password = password
 442
 443         out, err := yaml.Marshal(&account)
 444         if err != nil {
 445                 return err
 446         }
 447
 448         if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
 449                 return err
 450         }
 451
 452         return nil
 453 }
 454
 455 // DeleteUser deletes the user account
 456 func (s *Server) DeleteUser(login string) error {
 457         s.mux.Lock()
 458         defer s.mux.Unlock()
 459
 460         delete(s.Accounts, login)
 461
 462         return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))
 463 }
 464
 465 func (s *Server) connectedUsers() []Field {
 466         s.mux.Lock()
 467         defer s.mux.Unlock()
 468
 469         var connectedUsers []Field
 470         for _, c := range sortedClients(s.Clients) {
 471                 if !c.Agreed {
 472                         continue
 473                 }
 474                 user := User{
 475                         ID:    *c.ID,
 476                         Icon:  c.Icon,
 477                         Flags: c.Flags,
 478                         Name:  string(c.UserName),
 479                 }
 480                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 481         }
 482         return connectedUsers
 483 }
 484
 485 func (s *Server) loadBanList(path string) error {
 486         fh, err := os.Open(path)
 487         if err != nil {
 488                 return err
 489         }
 490         decoder := yaml.NewDecoder(fh)
 491
 492         return decoder.Decode(s.banList)
 493 }
 494
 495 // loadThreadedNews loads the threaded news data from disk
 496 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 497         fh, err := os.Open(threadedNewsPath)
 498         if err != nil {
 499                 return err
 500         }
 501         decoder := yaml.NewDecoder(fh)
 502
 503         return decoder.Decode(s.ThreadedNews)
 504 }
 505
 506 // loadAccounts loads account data from disk
 507 func (s *Server) loadAccounts(userDir string) error {
 508         matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
 509         if err != nil {
 510                 return err
 511         }
 512
 513         if len(matches) == 0 {
 514                 return errors.New("no user accounts found in " + userDir)
 515         }
 516
 517         for _, file := range matches {
 518                 fh, err := s.FS.Open(file)
 519                 if err != nil {
 520                         return err
 521                 }
 522
 523                 account := Account{}
 524                 decoder := yaml.NewDecoder(fh)
 525                 if err := decoder.Decode(&account); err != nil {
 526                         return err
 527                 }
 528
 529                 s.Accounts[account.Login] = &account
 530         }
 531         return nil
 532 }
 533
 534 func (s *Server) loadConfig(path string) error {
 535         fh, err := s.FS.Open(path)
 536         if err != nil {
 537                 return err
 538         }
 539
 540         decoder := yaml.NewDecoder(fh)
 541         err = decoder.Decode(s.Config)
 542         if err != nil {
 543                 return err
 544         }
 545
 546         validate := validator.New()
 547         err = validate.Struct(s.Config)
 548         if err != nil {
 549                 return err
 550         }
 551         return nil
 552 }
 553
 554 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 555 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 556         defer dontPanic(s.Logger)
 557
 558         if err := Handshake(rwc); err != nil {
 559                 return err
 560         }
 561
 562         // Create a new scanner for parsing incoming bytes into transaction tokens
 563         scanner := bufio.NewScanner(rwc)
 564         scanner.Split(transactionScanner)
 565
 566         scanner.Scan()
 567
 568         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 569         // scanner re-uses the buffer for subsequent scans.
 570         buf := make([]byte, len(scanner.Bytes()))
 571         copy(buf, scanner.Bytes())
 572
 573         var clientLogin Transaction
 574         if _, err := clientLogin.Write(buf); err != nil {
 575                 return err
 576         }
 577
 578         c := s.NewClientConn(rwc, remoteAddr)
 579
 580         // check if remoteAddr is present in the ban list
 581         if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
 582                 // permaban
 583                 if banUntil == nil {
 584                         s.outbox <- *NewTransaction(
 585                                 tranServerMsg,
 586                                 c.ID,
 587                                 NewField(fieldData, []byte("You are permanently banned on this server")),
 588                                 NewField(fieldChatOptions, []byte{0, 0}),
 589                         )
 590                         time.Sleep(1 * time.Second)
 591                         return nil
 592                 } else if time.Now().Before(*banUntil) {
 593                         s.outbox <- *NewTransaction(
 594                                 tranServerMsg,
 595                                 c.ID,
 596                                 NewField(fieldData, []byte("You are temporarily banned on this server")),
 597                                 NewField(fieldChatOptions, []byte{0, 0}),
 598                         )
 599                         time.Sleep(1 * time.Second)
 600                         return nil
 601                 }
 602
 603         }
 604         defer c.Disconnect()
 605
 606         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 607         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 608         c.Version = clientLogin.GetField(fieldVersion).Data
 609
 610         var login string
 611         for _, char := range encodedLogin {
 612                 login += string(rune(255 - uint(char)))
 613         }
 614         if login == "" {
 615                 login = GuestAccount
 616         }
 617
 618         c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
 619
 620         // If authentication fails, send error reply and close connection
 621         if !c.Authenticate(login, encodedPassword) {
 622                 t := c.NewErrReply(&clientLogin, "Incorrect login.")
 623                 b, err := t.MarshalBinary()
 624                 if err != nil {
 625                         return err
 626                 }
 627                 if _, err := rwc.Write(b); err != nil {
 628                         return err
 629                 }
 630
 631                 c.logger.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 632
 633                 return nil
 634         }
 635
 636         if clientLogin.GetField(fieldUserIconID).Data != nil {
 637                 c.Icon = clientLogin.GetField(fieldUserIconID).Data
 638         }
 639
 640         c.Account = c.Server.Accounts[login]
 641
 642         if clientLogin.GetField(fieldUserName).Data != nil {
 643                 if c.Authorize(accessAnyName) {
 644                         c.UserName = clientLogin.GetField(fieldUserName).Data
 645                 } else {
 646                         c.UserName = []byte(c.Account.Name)
 647                 }
 648         }
 649
 650         if c.Authorize(accessDisconUser) {
 651                 c.Flags = []byte{0, 2}
 652         }
 653
 654         s.outbox <- c.NewReply(&clientLogin,
 655                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 656                 NewField(fieldCommunityBannerID, []byte{0, 0}),
 657                 NewField(fieldServerName, []byte(s.Config.Name)),
 658         )
 659
 660         // Send user access privs so client UI knows how to behave
 661         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, c.Account.Access[:]))
 662
 663         // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
 664         // client versions.  For 1.2.3 client, we do not send tranShowAgreement.  For other client versions, we send
 665         // tranShowAgreement but with the NoServerAgreement field set to 1.
 666         if c.Authorize(accessNoAgreement) {
 667                 // If client version is nil, then the client uses the 1.2.3 login behavior
 668                 if c.Version != nil {
 669                         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldNoServerAgreement, []byte{1}))
 670                 }
 671         } else {
 672                 c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 673         }
 674
 675         // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
 676         if c.Version == nil || bytes.Equal(c.Version, nostalgiaVersion) || bytes.Equal(c.Version, frogblastVersion) {
 677                 c.Agreed = true
 678                 c.logger = c.logger.With("name", string(c.UserName))
 679                 c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(c.Version); return i }()))
 680
 681                 for _, t := range c.notifyOthers(
 682                         *NewTransaction(
 683                                 tranNotifyChangeUser, nil,
 684                                 NewField(fieldUserName, c.UserName),
 685                                 NewField(fieldUserID, *c.ID),
 686                                 NewField(fieldUserIconID, c.Icon),
 687                                 NewField(fieldUserFlags, c.Flags),
 688                         ),
 689                 ) {
 690                         c.Server.outbox <- t
 691                 }
 692         }
 693
 694         c.Server.Stats.ConnectionCounter += 1
 695         if len(s.Clients) > c.Server.Stats.ConnectionPeak {
 696                 c.Server.Stats.ConnectionPeak = len(s.Clients)
 697         }
 698
 699         // Scan for new transactions and handle them as they come in.
 700         for scanner.Scan() {
 701                 // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 702                 // scanner re-uses the buffer for subsequent scans.
 703                 buf := make([]byte, len(scanner.Bytes()))
 704                 copy(buf, scanner.Bytes())
 705
 706                 var t Transaction
 707                 if _, err := t.Write(buf); err != nil {
 708                         return err
 709                 }
 710
 711                 if err := c.handleTransaction(t); err != nil {
 712                         c.logger.Errorw("Error handling transaction", "err", err)
 713                 }
 714         }
 715         return nil
 716 }
 717
 718 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 719         s.PrivateChatsMu.Lock()
 720         defer s.PrivateChatsMu.Unlock()
 721
 722         randID := make([]byte, 4)
 723         rand.Read(randID)
 724         data := binary.BigEndian.Uint32(randID[:])
 725
 726         s.PrivateChats[data] = &PrivateChat{
 727                 ClientConn: make(map[uint16]*ClientConn),
 728         }
 729         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 730
 731         return randID
 732 }
 733
 734 const dlFldrActionSendFile = 1
 735 const dlFldrActionResumeFile = 2
 736 const dlFldrActionNextFile = 3
 737
 738 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 739 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 740         defer dontPanic(s.Logger)
 741
 742         txBuf := make([]byte, 16)
 743         if _, err := io.ReadFull(rwc, txBuf); err != nil {
 744                 return err
 745         }
 746
 747         var t transfer
 748         if _, err := t.Write(txBuf); err != nil {
 749                 return err
 750         }
 751
 752         defer func() {
 753                 s.mux.Lock()
 754                 delete(s.fileTransfers, t.ReferenceNumber)
 755                 s.mux.Unlock()
 756
 757                 // Wait a few seconds before closing the connection: this is a workaround for problems
 758                 // observed with Windows clients where the client must initiate close of the TCP connection before
 759                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 760                 time.Sleep(3 * time.Second)
 761         }()
 762
 763         s.mux.Lock()
 764         fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
 765         s.mux.Unlock()
 766         if !ok {
 767                 return errors.New("invalid transaction ID")
 768         }
 769
 770         defer func() {
 771                 fileTransfer.ClientConn.transfersMU.Lock()
 772                 delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
 773                 fileTransfer.ClientConn.transfersMU.Unlock()
 774         }()
 775
 776         rLogger := s.Logger.With(
 777                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 778                 "login", fileTransfer.ClientConn.Account.Login,
 779                 "name", string(fileTransfer.ClientConn.UserName),
 780         )
 781
 782         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 783         if err != nil {
 784                 return err
 785         }
 786
 787         switch fileTransfer.Type {
 788         case bannerDownload:
 789                 if err := s.bannerDownload(rwc); err != nil {
 790                         return err
 791                 }
 792         case FileDownload:
 793                 s.Stats.DownloadCounter += 1
 794                 s.Stats.DownloadsInProgress += 1
 795                 defer func() {
 796                         s.Stats.DownloadsInProgress -= 1
 797                 }()
 798
 799                 var dataOffset int64
 800                 if fileTransfer.fileResumeData != nil {
 801                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 802                 }
 803
 804                 fw, err := newFileWrapper(s.FS, fullPath, 0)
 805                 if err != nil {
 806                         return err
 807                 }
 808
 809                 rLogger.Infow("File download started", "filePath", fullPath)
 810
 811                 // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
 812                 if fileTransfer.options == nil {
 813                         // Start by sending flat file object to client
 814                         if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
 815                                 return err
 816                         }
 817                 }
 818
 819                 file, err := fw.dataForkReader()
 820                 if err != nil {
 821                         return err
 822                 }
 823
 824                 br := bufio.NewReader(file)
 825                 if _, err := br.Discard(int(dataOffset)); err != nil {
 826                         return err
 827                 }
 828
 829                 if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
 830                         return err
 831                 }
 832
 833                 // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
 834                 if fileTransfer.fileResumeData == nil {
 835                         err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
 836                         if err != nil {
 837                                 return err
 838                         }
 839                 }
 840
 841                 rFile, err := fw.rsrcForkFile()
 842                 if err != nil {
 843                         return nil
 844                 }
 845
 846                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
 847                         return err
 848                 }
 849
 850         case FileUpload:
 851                 s.Stats.UploadCounter += 1
 852                 s.Stats.UploadsInProgress += 1
 853                 defer func() { s.Stats.UploadsInProgress -= 1 }()
 854
 855                 var file *os.File
 856
 857                 // A file upload has three possible cases:
 858                 // 1) Upload a new file
 859                 // 2) Resume a partially transferred file
 860                 // 3) Replace a fully uploaded file
 861                 //  We have to infer which case applies by inspecting what is already on the filesystem
 862
 863                 // 1) Check for existing file:
 864                 _, err = os.Stat(fullPath)
 865                 if err == nil {
 866                         return errors.New("existing file found at " + fullPath)
 867                 }
 868                 if errors.Is(err, fs.ErrNotExist) {
 869                         // If not found, open or create a new .incomplete file
 870                         file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 871                         if err != nil {
 872                                 return err
 873                         }
 874                 }
 875
 876                 f, err := newFileWrapper(s.FS, fullPath, 0)
 877                 if err != nil {
 878                         return err
 879                 }
 880
 881                 rLogger.Infow("File upload started", "dstFile", fullPath)
 882
 883                 rForkWriter := io.Discard
 884                 iForkWriter := io.Discard
 885                 if s.Config.PreserveResourceForks {
 886                         rForkWriter, err = f.rsrcForkWriter()
 887                         if err != nil {
 888                                 return err
 889                         }
 890
 891                         iForkWriter, err = f.infoForkWriter()
 892                         if err != nil {
 893                                 return err
 894                         }
 895                 }
 896
 897                 if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
 898                         s.Logger.Error(err)
 899                 }
 900
 901                 if err := file.Close(); err != nil {
 902                         return err
 903                 }
 904
 905                 if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
 906                         return err
 907                 }
 908
 909                 rLogger.Infow("File upload complete", "dstFile", fullPath)
 910
 911         case FolderDownload:
 912                 s.Stats.DownloadCounter += 1
 913                 s.Stats.DownloadsInProgress += 1
 914                 defer func() { s.Stats.DownloadsInProgress -= 1 }()
 915
 916                 // Folder Download flow:
 917                 // 1. Get filePath from the transfer
 918                 // 2. Iterate over files
 919                 // 3. For each fileWrapper:
 920                 //       Send fileWrapper header to client
 921                 // The client can reply in 3 ways:
 922                 //
 923                 // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
 924                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
 925                 //
 926                 // 2. If download of a fileWrapper is to be resumed:
 927                 //              client sends:
 928                 //                      []byte{0x00, 0x02} // download folder action
 929                 //                      [2]byte // Resume data size
 930                 //                      []byte fileWrapper resume data (see myField_FileResumeData)
 931                 //
 932                 // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
 933                 //
 934                 // When download is requested (case 2 or 3), server replies with:
 935                 //                      [4]byte - fileWrapper size
 936                 //                      []byte  - Flattened File Object
 937                 //
 938                 // After every fileWrapper download, client could request next fileWrapper with:
 939                 //                      []byte{0x00, 0x03}
 940                 //
 941                 // This notifies the server to send the next item header
 942
 943                 basePathLen := len(fullPath)
 944
 945                 rLogger.Infow("Start folder download", "path", fullPath)
 946
 947                 nextAction := make([]byte, 2)
 948                 if _, err := io.ReadFull(rwc, nextAction); err != nil {
 949                         return err
 950                 }
 951
 952                 i := 0
 953                 err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
 954                         s.Stats.DownloadCounter += 1
 955                         i += 1
 956
 957                         if err != nil {
 958                                 return err
 959                         }
 960
 961                         // skip dot files
 962                         if strings.HasPrefix(info.Name(), ".") {
 963                                 return nil
 964                         }
 965
 966                         hlFile, err := newFileWrapper(s.FS, path, 0)
 967                         if err != nil {
 968                                 return err
 969                         }
 970
 971                         subPath := path[basePathLen+1:]
 972                         rLogger.Debugw("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 973
 974                         if i == 1 {
 975                                 return nil
 976                         }
 977
 978                         fileHeader := NewFileHeader(subPath, info.IsDir())
 979
 980                         // Send the fileWrapper header to client
 981                         if _, err := rwc.Write(fileHeader.Payload()); err != nil {
 982                                 s.Logger.Errorf("error sending file header: %v", err)
 983                                 return err
 984                         }
 985
 986                         // Read the client's Next Action request
 987                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
 988                                 return err
 989                         }
 990
 991                         rLogger.Debugw("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 992
 993                         var dataOffset int64
 994
 995                         switch nextAction[1] {
 996                         case dlFldrActionResumeFile:
 997                                 // get size of resumeData
 998                                 resumeDataByteLen := make([]byte, 2)
 999                                 if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
1000                                         return err
1001                                 }
1002
1003                                 resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
1004                                 resumeDataBytes := make([]byte, resumeDataLen)
1005                                 if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
1006                                         return err
1007                                 }
1008
1009                                 var frd FileResumeData
1010                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
1011                                         return err
1012                                 }
1013                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1014                         case dlFldrActionNextFile:
1015                                 // client asked to skip this file
1016                                 return nil
1017                         }
1018
1019                         if info.IsDir() {
1020                                 return nil
1021                         }
1022
1023                         rLogger.Infow("File download started",
1024                                 "fileName", info.Name(),
1025                                 "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
1026                         )
1027
1028                         // Send file size to client
1029                         if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
1030                                 s.Logger.Error(err)
1031                                 return err
1032                         }
1033
1034                         // Send ffo bytes to client
1035                         if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
1036                                 s.Logger.Error(err)
1037                                 return err
1038                         }
1039
1040                         file, err := s.FS.Open(path)
1041                         if err != nil {
1042                                 return err
1043                         }
1044
1045                         // wr := bufio.NewWriterSize(rwc, 1460)
1046                         if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
1047                                 return err
1048                         }
1049
1050                         if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
1051                                 err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
1052                                 if err != nil {
1053                                         return err
1054                                 }
1055
1056                                 rFile, err := hlFile.rsrcForkFile()
1057                                 if err != nil {
1058                                         return err
1059                                 }
1060
1061                                 if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
1062                                         return err
1063                                 }
1064                         }
1065
1066                         // Read the client's Next Action request.  This is always 3, I think?
1067                         if _, err := io.ReadFull(rwc, nextAction); err != nil {
1068                                 return err
1069                         }
1070
1071                         return nil
1072                 })
1073
1074                 if err != nil {
1075                         return err
1076                 }
1077
1078         case FolderUpload:
1079                 s.Stats.UploadCounter += 1
1080                 s.Stats.UploadsInProgress += 1
1081                 defer func() { s.Stats.UploadsInProgress -= 1 }()
1082                 rLogger.Infow(
1083                         "Folder upload started",
1084                         "dstPath", fullPath,
1085                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
1086                         "FolderItemCount", fileTransfer.FolderItemCount,
1087                 )
1088
1089                 // Check if the target folder exists.  If not, create it.
1090                 if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
1091                         if err := s.FS.Mkdir(fullPath, 0777); err != nil {
1092                                 return err
1093                         }
1094                 }
1095
1096                 // Begin the folder upload flow by sending the "next file action" to client
1097                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1098                         return err
1099                 }
1100
1101                 fileSize := make([]byte, 4)
1102
1103                 for i := 0; i < fileTransfer.ItemCount(); i++ {
1104                         s.Stats.UploadCounter += 1
1105
1106                         var fu folderUpload
1107                         if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
1108                                 return err
1109                         }
1110                         if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
1111                                 return err
1112                         }
1113                         if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
1114                                 return err
1115                         }
1116
1117                         fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
1118
1119                         if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
1120                                 return err
1121                         }
1122
1123                         rLogger.Infow(
1124                                 "Folder upload continued",
1125                                 "FormattedPath", fu.FormattedPath(),
1126                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
1127                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
1128                         )
1129
1130                         if fu.IsFolder == [2]byte{0, 1} {
1131                                 if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
1132                                         if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
1133                                                 return err
1134                                         }
1135                                 }
1136
1137                                 // Tell client to send next file
1138                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1139                                         return err
1140                                 }
1141                         } else {
1142                                 nextAction := dlFldrActionSendFile
1143
1144                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
1145                                 _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
1146                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1147                                         return err
1148                                 }
1149                                 if err == nil {
1150                                         nextAction = dlFldrActionNextFile
1151                                 }
1152
1153                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
1154                                 incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
1155                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1156                                         return err
1157                                 }
1158                                 if err == nil {
1159                                         nextAction = dlFldrActionResumeFile
1160                                 }
1161
1162                                 if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
1163                                         return err
1164                                 }
1165
1166                                 switch nextAction {
1167                                 case dlFldrActionNextFile:
1168                                         continue
1169                                 case dlFldrActionResumeFile:
1170                                         offset := make([]byte, 4)
1171                                         binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
1172
1173                                         file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1174                                         if err != nil {
1175                                                 return err
1176                                         }
1177
1178                                         fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
1179
1180                                         b, _ := fileResumeData.BinaryMarshal()
1181
1182                                         bs := make([]byte, 2)
1183                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1184
1185                                         if _, err := rwc.Write(append(bs, b...)); err != nil {
1186                                                 return err
1187                                         }
1188
1189                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1190                                                 return err
1191                                         }
1192
1193                                         if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
1194                                                 s.Logger.Error(err)
1195                                         }
1196
1197                                         err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
1198                                         if err != nil {
1199                                                 return err
1200                                         }
1201
1202                                 case dlFldrActionSendFile:
1203                                         if _, err := io.ReadFull(rwc, fileSize); err != nil {
1204                                                 return err
1205                                         }
1206
1207                                         filePath := filepath.Join(fullPath, fu.FormattedPath())
1208
1209                                         hlFile, err := newFileWrapper(s.FS, filePath, 0)
1210                                         if err != nil {
1211                                                 return err
1212                                         }
1213
1214                                         rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
1215
1216                                         incWriter, err := hlFile.incFileWriter()
1217                                         if err != nil {
1218                                                 return err
1219                                         }
1220
1221                                         rForkWriter := io.Discard
1222                                         iForkWriter := io.Discard
1223                                         if s.Config.PreserveResourceForks {
1224                                                 iForkWriter, err = hlFile.infoForkWriter()
1225                                                 if err != nil {
1226                                                         return err
1227                                                 }
1228
1229                                                 rForkWriter, err = hlFile.rsrcForkWriter()
1230                                                 if err != nil {
1231                                                         return err
1232                                                 }
1233                                         }
1234                                         if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
1235                                                 return err
1236                                         }
1237
1238                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1239                                                 return err
1240                                         }
1241                                 }
1242
1243                                 // Tell client to send next fileWrapper
1244                                 if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1245                                         return err
1246                                 }
1247                         }
1248                 }
1249                 rLogger.Infof("Folder upload complete")
1250         }
1251
1252         return nil
1253 }