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