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

   1 package hotline
   2
   3 import (
   4         "context"
   5         "encoding/binary"
   6         "errors"
   7         "fmt"
   8         "go.uber.org/zap"
   9         "io"
  10         "io/fs"
  11         "io/ioutil"
  12         "math/big"
  13         "math/rand"
  14         "net"
  15         "os"
  16         "path"
  17         "path/filepath"
  18         "runtime/debug"
  19         "sort"
  20         "strings"
  21         "sync"
  22         "time"
  23
  24         "gopkg.in/yaml.v3"
  25 )
  26
  27 const (
  28         userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
  29         idleCheckInterval      = 10  // time in seconds to check for idle users
  30         trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
  31 )
  32
  33 type Server struct {
  34         Port          int
  35         Accounts      map[string]*Account
  36         Agreement     []byte
  37         Clients       map[uint16]*ClientConn
  38         FlatNews      []byte
  39         ThreadedNews  *ThreadedNews
  40         FileTransfers map[uint32]*FileTransfer
  41         Config        *Config
  42         ConfigDir     string
  43         Logger        *zap.SugaredLogger
  44         PrivateChats  map[uint32]*PrivateChat
  45         NextGuestID   *uint16
  46         TrackerPassID []byte
  47         Stats         *Stats
  48
  49         APIListener  net.Listener
  50         FileListener net.Listener
  51
  52         // newsReader io.Reader
  53         // newsWriter io.WriteCloser
  54
  55         outbox chan Transaction
  56
  57         mux         sync.Mutex
  58         flatNewsMux sync.Mutex
  59 }
  60
  61 type PrivateChat struct {
  62         Subject    string
  63         ClientConn map[uint16]*ClientConn
  64 }
  65
  66 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  67         s.Logger.Infow("Hotline server started", "version", VERSION)
  68         var wg sync.WaitGroup
  69
  70         wg.Add(1)
  71         go func() { s.Logger.Fatal(s.Serve(ctx, cancelRoot, s.APIListener)) }()
  72
  73         wg.Add(1)
  74         go func() { s.Logger.Fatal(s.ServeFileTransfers(s.FileListener)) }()
  75
  76         wg.Wait()
  77
  78         return nil
  79 }
  80
  81 func (s *Server) APIPort() int {
  82         return s.APIListener.Addr().(*net.TCPAddr).Port
  83 }
  84
  85 func (s *Server) ServeFileTransfers(ln net.Listener) error {
  86         s.Logger.Infow("Hotline file transfer server started", "Addr", fmt.Sprintf(":%v", s.Port+1))
  87
  88         for {
  89                 conn, err := ln.Accept()
  90                 if err != nil {
  91                         return err
  92                 }
  93
  94                 go func() {
  95                         if err := s.handleFileTransfer(conn); err != nil {
  96                                 s.Logger.Errorw("file transfer error", "reason", err)
  97                         }
  98                 }()
  99         }
 100 }
 101
 102 func (s *Server) sendTransaction(t Transaction) error {
 103         requestNum := binary.BigEndian.Uint16(t.Type)
 104         clientID, err := byteToInt(*t.clientID)
 105         if err != nil {
 106                 return err
 107         }
 108
 109         s.mux.Lock()
 110         client := s.Clients[uint16(clientID)]
 111         s.mux.Unlock()
 112         if client == nil {
 113                 return fmt.Errorf("invalid client id %v", *t.clientID)
 114         }
 115         userName := string(client.UserName)
 116         login := client.Account.Login
 117
 118         handler := TransactionHandlers[requestNum]
 119
 120         b, err := t.MarshalBinary()
 121         if err != nil {
 122                 return err
 123         }
 124         var n int
 125         if n, err = client.Connection.Write(b); err != nil {
 126                 return err
 127         }
 128         s.Logger.Debugw("Sent Transaction",
 129                 "name", userName,
 130                 "login", login,
 131                 "IsReply", t.IsReply,
 132                 "type", handler.Name,
 133                 "sentBytes", n,
 134                 "remoteAddr", client.Connection.RemoteAddr(),
 135         )
 136         return nil
 137 }
 138
 139 func (s *Server) Serve(ctx context.Context, cancelRoot context.CancelFunc, ln net.Listener) error {
 140         s.Logger.Infow("Hotline server started", "Addr", fmt.Sprintf(":%v", s.Port))
 141
 142         for {
 143                 conn, err := ln.Accept()
 144                 if err != nil {
 145                         s.Logger.Errorw("error accepting connection", "err", err)
 146                 }
 147
 148                 go func() {
 149                         for {
 150                                 t := <-s.outbox
 151                                 go func() {
 152                                         if err := s.sendTransaction(t); err != nil {
 153                                                 s.Logger.Errorw("error sending transaction", "err", err)
 154                                         }
 155                                 }()
 156                         }
 157                 }()
 158                 go func() {
 159                         if err := s.handleNewConnection(conn); err != nil {
 160                                 if err == io.EOF {
 161                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 162                                 } else {
 163                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 164                                 }
 165                         }
 166                 }()
 167         }
 168 }
 169
 170 const (
 171         agreementFile = "Agreement.txt"
 172 )
 173
 174 // NewServer constructs a new Server from a config dir
 175 func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredLogger) (*Server, error) {
 176         server := Server{
 177                 Port:          netPort,
 178                 Accounts:      make(map[string]*Account),
 179                 Config:        new(Config),
 180                 Clients:       make(map[uint16]*ClientConn),
 181                 FileTransfers: make(map[uint32]*FileTransfer),
 182                 PrivateChats:  make(map[uint32]*PrivateChat),
 183                 ConfigDir:     configDir,
 184                 Logger:        logger,
 185                 NextGuestID:   new(uint16),
 186                 outbox:        make(chan Transaction),
 187                 Stats:         &Stats{StartTime: time.Now()},
 188                 ThreadedNews:  &ThreadedNews{},
 189                 TrackerPassID: make([]byte, 4),
 190         }
 191
 192         ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
 193         if err != nil {
 194                 return nil, err
 195         }
 196         server.APIListener = ln
 197
 198         if netPort != 0 {
 199                 netPort += 1
 200         }
 201
 202         ln2, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
 203         server.FileListener = ln2
 204         if err != nil {
 205                 return nil, err
 206         }
 207
 208         // generate a new random passID for tracker registration
 209         if _, err := rand.Read(server.TrackerPassID); err != nil {
 210                 return nil, err
 211         }
 212
 213         server.Logger.Debugw("Loading Agreement", "path", configDir+agreementFile)
 214         if server.Agreement, err = os.ReadFile(configDir + agreementFile); err != nil {
 215                 return nil, err
 216         }
 217
 218         if server.FlatNews, err = os.ReadFile(configDir + "MessageBoard.txt"); err != nil {
 219                 return nil, err
 220         }
 221
 222         if err := server.loadThreadedNews(configDir + "ThreadedNews.yaml"); err != nil {
 223                 return nil, err
 224         }
 225
 226         if err := server.loadConfig(configDir + "config.yaml"); err != nil {
 227                 return nil, err
 228         }
 229
 230         if err := server.loadAccounts(configDir + "Users/"); err != nil {
 231                 return nil, err
 232         }
 233
 234         server.Config.FileRoot = configDir + "Files/"
 235
 236         *server.NextGuestID = 1
 237
 238         if server.Config.EnableTrackerRegistration {
 239                 go func() {
 240                         for {
 241                                 tr := TrackerRegistration{
 242                                         Port:        []byte{0x15, 0x7c},
 243                                         UserCount:   server.userCount(),
 244                                         PassID:      server.TrackerPassID,
 245                                         Name:        server.Config.Name,
 246                                         Description: server.Config.Description,
 247                                 }
 248                                 for _, t := range server.Config.Trackers {
 249                                         server.Logger.Infof("Registering with tracker %v", t)
 250
 251                                         if err := register(t, tr); err != nil {
 252                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 253                                         }
 254                                 }
 255
 256                                 time.Sleep(trackerUpdateFrequency * time.Second)
 257                         }
 258                 }()
 259         }
 260
 261         // Start Client Keepalive go routine
 262         go server.keepaliveHandler()
 263
 264         return &server, nil
 265 }
 266
 267 func (s *Server) userCount() int {
 268         s.mux.Lock()
 269         defer s.mux.Unlock()
 270
 271         return len(s.Clients)
 272 }
 273
 274 func (s *Server) keepaliveHandler() {
 275         for {
 276                 time.Sleep(idleCheckInterval * time.Second)
 277                 s.mux.Lock()
 278
 279                 for _, c := range s.Clients {
 280                         c.IdleTime += idleCheckInterval
 281                         if c.IdleTime > userIdleSeconds && !c.Idle {
 282                                 c.Idle = true
 283
 284                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
 285                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 286                                 binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
 287
 288                                 c.sendAll(
 289                                         tranNotifyChangeUser,
 290                                         NewField(fieldUserID, *c.ID),
 291                                         NewField(fieldUserFlags, *c.Flags),
 292                                         NewField(fieldUserName, c.UserName),
 293                                         NewField(fieldUserIconID, *c.Icon),
 294                                 )
 295                         }
 296                 }
 297                 s.mux.Unlock()
 298         }
 299 }
 300
 301 func (s *Server) writeThreadedNews() error {
 302         s.mux.Lock()
 303         defer s.mux.Unlock()
 304
 305         out, err := yaml.Marshal(s.ThreadedNews)
 306         if err != nil {
 307                 return err
 308         }
 309         err = ioutil.WriteFile(
 310                 s.ConfigDir+"ThreadedNews.yaml",
 311                 out,
 312                 0666,
 313         )
 314         return err
 315 }
 316
 317 func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
 318         s.mux.Lock()
 319         defer s.mux.Unlock()
 320
 321         clientConn := &ClientConn{
 322                 ID:         &[]byte{0, 0},
 323                 Icon:       &[]byte{0, 0},
 324                 Flags:      &[]byte{0, 0},
 325                 UserName:   []byte{},
 326                 Connection: conn,
 327                 Server:     s,
 328                 Version:    &[]byte{},
 329                 AutoReply:  []byte{},
 330                 Transfers:  make(map[int][]*FileTransfer),
 331                 Agreed:     false,
 332         }
 333         *s.NextGuestID++
 334         ID := *s.NextGuestID
 335
 336         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 337         s.Clients[ID] = clientConn
 338
 339         return clientConn
 340 }
 341
 342 // NewUser creates a new user account entry in the server map and config file
 343 func (s *Server) NewUser(login, name, password string, access []byte) error {
 344         s.mux.Lock()
 345         defer s.mux.Unlock()
 346
 347         account := Account{
 348                 Login:    login,
 349                 Name:     name,
 350                 Password: hashAndSalt([]byte(password)),
 351                 Access:   &access,
 352         }
 353         out, err := yaml.Marshal(&account)
 354         if err != nil {
 355                 return err
 356         }
 357         s.Accounts[login] = &account
 358
 359         return FS.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
 360 }
 361
 362 func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
 363         s.mux.Lock()
 364         defer s.mux.Unlock()
 365
 366         fmt.Printf("login: %v, newLogin: %v: ", login, newLogin)
 367
 368         // update renames the user login
 369         if login != newLogin {
 370                 err := os.Rename(s.ConfigDir+"Users/"+login+".yaml", s.ConfigDir+"Users/"+newLogin+".yaml")
 371                 if err != nil {
 372                         return err
 373                 }
 374                 s.Accounts[newLogin] = s.Accounts[login]
 375                 delete(s.Accounts, login)
 376         }
 377
 378         account := s.Accounts[newLogin]
 379         account.Access = &access
 380         account.Name = name
 381         account.Password = password
 382
 383         out, err := yaml.Marshal(&account)
 384         if err != nil {
 385                 return err
 386         }
 387         if err := os.WriteFile(s.ConfigDir+"Users/"+newLogin+".yaml", out, 0666); err != nil {
 388                 return err
 389         }
 390
 391         return nil
 392 }
 393
 394 // DeleteUser deletes the user account
 395 func (s *Server) DeleteUser(login string) error {
 396         s.mux.Lock()
 397         defer s.mux.Unlock()
 398
 399         delete(s.Accounts, login)
 400
 401         return FS.Remove(s.ConfigDir + "Users/" + login + ".yaml")
 402 }
 403
 404 func (s *Server) connectedUsers() []Field {
 405         s.mux.Lock()
 406         defer s.mux.Unlock()
 407
 408         var connectedUsers []Field
 409         for _, c := range sortedClients(s.Clients) {
 410                 if !c.Agreed {
 411                         continue
 412                 }
 413                 user := User{
 414                         ID:    *c.ID,
 415                         Icon:  *c.Icon,
 416                         Flags: *c.Flags,
 417                         Name:  string(c.UserName),
 418                 }
 419                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 420         }
 421         return connectedUsers
 422 }
 423
 424 // loadThreadedNews loads the threaded news data from disk
 425 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 426         fh, err := os.Open(threadedNewsPath)
 427         if err != nil {
 428                 return err
 429         }
 430         decoder := yaml.NewDecoder(fh)
 431
 432         return decoder.Decode(s.ThreadedNews)
 433 }
 434
 435 // loadAccounts loads account data from disk
 436 func (s *Server) loadAccounts(userDir string) error {
 437         matches, err := filepath.Glob(path.Join(userDir, "*.yaml"))
 438         if err != nil {
 439                 return err
 440         }
 441
 442         if len(matches) == 0 {
 443                 return errors.New("no user accounts found in " + userDir)
 444         }
 445
 446         for _, file := range matches {
 447                 fh, err := FS.Open(file)
 448                 if err != nil {
 449                         return err
 450                 }
 451
 452                 account := Account{}
 453                 decoder := yaml.NewDecoder(fh)
 454                 if err := decoder.Decode(&account); err != nil {
 455                         return err
 456                 }
 457
 458                 s.Accounts[account.Login] = &account
 459         }
 460         return nil
 461 }
 462
 463 func (s *Server) loadConfig(path string) error {
 464         fh, err := FS.Open(path)
 465         if err != nil {
 466                 return err
 467         }
 468
 469         decoder := yaml.NewDecoder(fh)
 470         err = decoder.Decode(s.Config)
 471         if err != nil {
 472                 return err
 473         }
 474         return nil
 475 }
 476
 477 const (
 478         minTransactionLen = 22 // minimum length of any transaction
 479 )
 480
 481 // dontPanic recovers and logs panics instead of crashing
 482 // TODO: remove this after known issues are fixed
 483 func dontPanic(logger *zap.SugaredLogger) {
 484         if r := recover(); r != nil {
 485                 fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 486                 logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 487         }
 488 }
 489
 490 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 491 func (s *Server) handleNewConnection(conn net.Conn) error {
 492         handshakeBuf := make([]byte, 12) // handshakes are always 12 bytes in length
 493         if _, err := conn.Read(handshakeBuf); err != nil {
 494                 return err
 495         }
 496         if err := Handshake(conn, handshakeBuf[:12]); err != nil {
 497                 return err
 498         }
 499
 500         buf := make([]byte, 1024)
 501         readLen, err := conn.Read(buf)
 502         if readLen < minTransactionLen {
 503                 return err
 504         }
 505         if err != nil {
 506                 return err
 507         }
 508
 509         clientLogin, _, err := ReadTransaction(buf[:readLen])
 510         if err != nil {
 511                 return err
 512         }
 513
 514         c := s.NewClientConn(conn)
 515
 516         defer c.Disconnect()
 517         defer dontPanic(s.Logger)
 518
 519         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 520         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 521         *c.Version = clientLogin.GetField(fieldVersion).Data
 522
 523         var login string
 524         for _, char := range encodedLogin {
 525                 login += string(rune(255 - uint(char)))
 526         }
 527         if login == "" {
 528                 login = GuestAccount
 529         }
 530
 531         // If authentication fails, send error reply and close connection
 532         if !c.Authenticate(login, encodedPassword) {
 533                 t := c.NewErrReply(clientLogin, "Incorrect login.")
 534                 b, err := t.MarshalBinary()
 535                 if err != nil {
 536                         return err
 537                 }
 538                 if _, err := conn.Write(b); err != nil {
 539                         return err
 540                 }
 541                 return fmt.Errorf("incorrect login")
 542         }
 543
 544         if clientLogin.GetField(fieldUserName).Data != nil {
 545                 c.UserName = clientLogin.GetField(fieldUserName).Data
 546         }
 547
 548         if clientLogin.GetField(fieldUserIconID).Data != nil {
 549                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 550         }
 551
 552         c.Account = c.Server.Accounts[login]
 553
 554         if c.Authorize(accessDisconUser) {
 555                 *c.Flags = []byte{0, 2}
 556         }
 557
 558         s.Logger.Infow("Client connection received", "login", login, "version", *c.Version, "RemoteAddr", conn.RemoteAddr().String())
 559
 560         s.outbox <- c.NewReply(clientLogin,
 561                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 562                 NewField(fieldCommunityBannerID, []byte{0x00, 0x01}),
 563                 NewField(fieldServerName, []byte(s.Config.Name)),
 564         )
 565
 566         // Send user access privs so client UI knows how to behave
 567         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 568
 569         // Show agreement to client
 570         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 571
 572         // assume simplified hotline v1.2.3 login flow that does not require agreement
 573         if *c.Version == nil {
 574                 c.Agreed = true
 575
 576                 c.notifyOthers(
 577                         *NewTransaction(
 578                                 tranNotifyChangeUser, nil,
 579                                 NewField(fieldUserName, c.UserName),
 580                                 NewField(fieldUserID, *c.ID),
 581                                 NewField(fieldUserIconID, *c.Icon),
 582                                 NewField(fieldUserFlags, *c.Flags),
 583                         ),
 584                 )
 585         }
 586
 587         c.Server.Stats.LoginCount += 1
 588
 589         const readBuffSize = 1024000 // 1KB - TODO: what should this be?
 590         tranBuff := make([]byte, 0)
 591         tReadlen := 0
 592         // Infinite loop where take action on incoming client requests until the connection is closed
 593         for {
 594                 buf = make([]byte, readBuffSize)
 595                 tranBuff = tranBuff[tReadlen:]
 596
 597                 readLen, err := c.Connection.Read(buf)
 598                 if err != nil {
 599                         return err
 600                 }
 601                 tranBuff = append(tranBuff, buf[:readLen]...)
 602
 603                 // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
 604                 // into a slice of transactions
 605                 var transactions []Transaction
 606                 if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
 607                         c.Server.Logger.Errorw("Error handling transaction", "err", err)
 608                 }
 609
 610                 // iterate over all of the transactions that were parsed from the byte slice and handle them
 611                 for _, t := range transactions {
 612                         if err := c.handleTransaction(&t); err != nil {
 613                                 c.Server.Logger.Errorw("Error handling transaction", "err", err)
 614                         }
 615                 }
 616         }
 617 }
 618
 619 // NewTransactionRef generates a random ID for the file transfer.  The Hotline client includes this ID
 620 // in the file transfer request payload, and the file transfer server will use it to map the request
 621 // to a transfer
 622 func (s *Server) NewTransactionRef() []byte {
 623         transactionRef := make([]byte, 4)
 624         rand.Read(transactionRef)
 625
 626         return transactionRef
 627 }
 628
 629 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 630         s.mux.Lock()
 631         defer s.mux.Unlock()
 632
 633         randID := make([]byte, 4)
 634         rand.Read(randID)
 635         data := binary.BigEndian.Uint32(randID[:])
 636
 637         s.PrivateChats[data] = &PrivateChat{
 638                 Subject:    "",
 639                 ClientConn: make(map[uint16]*ClientConn),
 640         }
 641         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 642
 643         return randID
 644 }
 645
 646 const dlFldrActionSendFile = 1
 647 const dlFldrActionResumeFile = 2
 648 const dlFldrActionNextFile = 3
 649
 650 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 651 func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
 652         defer func() {
 653
 654                 if err := conn.Close(); err != nil {
 655                         s.Logger.Errorw("error closing connection", "error", err)
 656                 }
 657         }()
 658
 659         defer dontPanic(s.Logger)
 660
 661         txBuf := make([]byte, 16)
 662         if _, err := io.ReadFull(conn, txBuf); err != nil {
 663                 return err
 664         }
 665
 666         var t transfer
 667         if _, err := t.Write(txBuf); err != nil {
 668                 return err
 669         }
 670
 671         transferRefNum := binary.BigEndian.Uint32(t.ReferenceNumber[:])
 672         defer func() {
 673                 s.mux.Lock()
 674                 delete(s.FileTransfers, transferRefNum)
 675                 s.mux.Unlock()
 676         }()
 677
 678         s.mux.Lock()
 679         fileTransfer, ok := s.FileTransfers[transferRefNum]
 680         s.mux.Unlock()
 681         if !ok {
 682                 return errors.New("invalid transaction ID")
 683         }
 684
 685         switch fileTransfer.Type {
 686         case FileDownload:
 687                 fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 688                 if err != nil {
 689                         return err
 690                 }
 691
 692                 var dataOffset int64
 693                 if fileTransfer.fileResumeData != nil {
 694                         dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
 695                 }
 696
 697                 ffo, err := NewFlattenedFileObject(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName, dataOffset)
 698                 if err != nil {
 699                         return err
 700                 }
 701
 702                 s.Logger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber)
 703
 704                 if fileTransfer.options == nil {
 705                         // Start by sending flat file object to client
 706                         if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
 707                                 return err
 708                         }
 709                 }
 710
 711                 file, err := FS.Open(fullFilePath)
 712                 if err != nil {
 713                         return err
 714                 }
 715
 716                 sendBuffer := make([]byte, 1048576)
 717                 var totalSent int64
 718                 for {
 719                         var bytesRead int
 720                         if bytesRead, err = file.ReadAt(sendBuffer, dataOffset+totalSent); err == io.EOF {
 721                                 if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
 722                                         return err
 723                                 }
 724                                 break
 725                         }
 726                         if err != nil {
 727                                 return err
 728                         }
 729                         totalSent += int64(bytesRead)
 730
 731                         fileTransfer.BytesSent += bytesRead
 732
 733                         if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
 734                                 return err
 735                         }
 736                 }
 737         case FileUpload:
 738                 destinationFile := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
 739                 tmpFile := destinationFile + ".incomplete"
 740
 741                 file, err := effectiveFile(destinationFile)
 742                 if errors.Is(err, fs.ErrNotExist) {
 743                         file, err = FS.Create(tmpFile)
 744                         if err != nil {
 745                                 return err
 746                         }
 747                 }
 748
 749                 defer func() { _ = file.Close() }()
 750
 751                 s.Logger.Infow("File upload started", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
 752
 753                 // TODO: replace io.Discard with a real file when ready to implement storing of resource fork data
 754                 if err := receiveFile(conn, file, io.Discard); err != nil {
 755                         return err
 756                 }
 757
 758                 if err := os.Rename(destinationFile+".incomplete", destinationFile); err != nil {
 759                         return err
 760                 }
 761
 762                 s.Logger.Infow("File upload complete", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
 763         case FolderDownload:
 764                 // Folder Download flow:
 765                 // 1. Get filePath from the transfer
 766                 // 2. Iterate over files
 767                 // 3. For each file:
 768                 //       Send file header to client
 769                 // The client can reply in 3 ways:
 770                 //
 771                 // 1. If type is an odd number (unknown type?), or file download for the current file is completed:
 772                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next file
 773                 //
 774                 // 2. If download of a file is to be resumed:
 775                 //              client sends:
 776                 //                      []byte{0x00, 0x02} // download folder action
 777                 //                      [2]byte // Resume data size
 778                 //                      []byte file resume data (see myField_FileResumeData)
 779                 //
 780                 // 3. Otherwise, download of the file is requested and client sends []byte{0x00, 0x01}
 781                 //
 782                 // When download is requested (case 2 or 3), server replies with:
 783                 //                      [4]byte - file size
 784                 //                      []byte  - Flattened File Object
 785                 //
 786                 // After every file download, client could request next file with:
 787                 //                      []byte{0x00, 0x03}
 788                 //
 789                 // This notifies the server to send the next item header
 790
 791                 fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 792                 if err != nil {
 793                         return err
 794                 }
 795
 796                 basePathLen := len(fullFilePath)
 797
 798                 s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber)
 799
 800                 nextAction := make([]byte, 2)
 801                 if _, err := conn.Read(nextAction); err != nil {
 802                         return err
 803                 }
 804
 805                 i := 0
 806                 err = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, err error) error {
 807                         if err != nil {
 808                                 return err
 809                         }
 810                         i += 1
 811                         subPath := path[basePathLen+1:]
 812                         s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())
 813
 814                         if i == 1 {
 815                                 return nil
 816                         }
 817
 818                         fileHeader := NewFileHeader(subPath, info.IsDir())
 819
 820                         // Send the file header to client
 821                         if _, err := conn.Write(fileHeader.Payload()); err != nil {
 822                                 s.Logger.Errorf("error sending file header: %v", err)
 823                                 return err
 824                         }
 825
 826                         // Read the client's Next Action request
 827                         if _, err := conn.Read(nextAction); err != nil {
 828                                 return err
 829                         }
 830
 831                         s.Logger.Infow("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 832
 833                         var dataOffset int64
 834
 835                         switch nextAction[1] {
 836                         case dlFldrActionResumeFile:
 837                                 // client asked to resume this file
 838                                 var frd FileResumeData
 839                                 // get size of resumeData
 840                                 if _, err := conn.Read(nextAction); err != nil {
 841                                         return err
 842                                 }
 843
 844                                 resumeDataLen := binary.BigEndian.Uint16(nextAction)
 845                                 resumeDataBytes := make([]byte, resumeDataLen)
 846                                 if _, err := conn.Read(resumeDataBytes); err != nil {
 847                                         return err
 848                                 }
 849
 850                                 if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
 851                                         return err
 852                                 }
 853                                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
 854                         case dlFldrActionNextFile:
 855                                 // client asked to skip this file
 856                                 return nil
 857                         }
 858
 859                         if info.IsDir() {
 860                                 return nil
 861                         }
 862
 863                         splitPath := strings.Split(path, "/")
 864
 865                         ffo, err := NewFlattenedFileObject(strings.Join(splitPath[:len(splitPath)-1], "/"), nil, []byte(info.Name()), dataOffset)
 866                         if err != nil {
 867                                 return err
 868                         }
 869                         s.Logger.Infow("File download started",
 870                                 "fileName", info.Name(),
 871                                 "transactionRef", fileTransfer.ReferenceNumber,
 872                                 "TransferSize", fmt.Sprintf("%x", ffo.TransferSize()),
 873                         )
 874
 875                         // Send file size to client
 876                         if _, err := conn.Write(ffo.TransferSize()); err != nil {
 877                                 s.Logger.Error(err)
 878                                 return err
 879                         }
 880
 881                         // Send ffo bytes to client
 882                         if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
 883                                 s.Logger.Error(err)
 884                                 return err
 885                         }
 886
 887                         file, err := FS.Open(path)
 888                         if err != nil {
 889                                 return err
 890                         }
 891
 892                         // // Copy N bytes from file to connection
 893                         // _, err = io.CopyN(conn, file, int64(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize[:])))
 894                         // if err != nil {
 895                         //      return err
 896                         // }
 897                         // file.Close()
 898                         sendBuffer := make([]byte, 1048576)
 899                         var totalSent int64
 900                         for {
 901                                 var bytesRead int
 902                                 if bytesRead, err = file.ReadAt(sendBuffer, dataOffset+totalSent); err == io.EOF {
 903                                         if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
 904                                                 return err
 905                                         }
 906                                         break
 907                                 }
 908                                 if err != nil {
 909                                         panic(err)
 910                                 }
 911                                 totalSent += int64(bytesRead)
 912
 913                                 fileTransfer.BytesSent += bytesRead
 914
 915                                 if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
 916                                         return err
 917                                 }
 918                         }
 919
 920                         // TODO: optionally send resource fork header and resource fork data
 921
 922                         // Read the client's Next Action request.  This is always 3, I think?
 923                         if _, err := conn.Read(nextAction); err != nil {
 924                                 return err
 925                         }
 926
 927                         return nil
 928                 })
 929
 930         case FolderUpload:
 931                 dstPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 932                 if err != nil {
 933                         return err
 934                 }
 935                 s.Logger.Infow(
 936                         "Folder upload started",
 937                         "transactionRef", fileTransfer.ReferenceNumber,
 938                         "dstPath", dstPath,
 939                         "TransferSize", fmt.Sprintf("%x", fileTransfer.TransferSize),
 940                         "FolderItemCount", fileTransfer.FolderItemCount,
 941                 )
 942
 943                 // Check if the target folder exists.  If not, create it.
 944                 if _, err := FS.Stat(dstPath); os.IsNotExist(err) {
 945                         if err := FS.Mkdir(dstPath, 0777); err != nil {
 946                                 return err
 947                         }
 948                 }
 949
 950                 // Begin the folder upload flow by sending the "next file action" to client
 951                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
 952                         return err
 953                 }
 954
 955                 fileSize := make([]byte, 4)
 956                 readBuffer := make([]byte, 1024)
 957
 958                 for i := 0; i < fileTransfer.ItemCount(); i++ {
 959
 960                         _, err := conn.Read(readBuffer)
 961                         if err != nil {
 962                                 return err
 963                         }
 964                         fu := readFolderUpload(readBuffer)
 965
 966                         s.Logger.Infow(
 967                                 "Folder upload continued",
 968                                 "transactionRef", fmt.Sprintf("%x", fileTransfer.ReferenceNumber),
 969                                 "FormattedPath", fu.FormattedPath(),
 970                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
 971                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
 972                         )
 973
 974                         if fu.IsFolder == [2]byte{0, 1} {
 975                                 if _, err := os.Stat(dstPath + "/" + fu.FormattedPath()); os.IsNotExist(err) {
 976                                         if err := os.Mkdir(dstPath+"/"+fu.FormattedPath(), 0777); err != nil {
 977                                                 return err
 978                                         }
 979                                 }
 980
 981                                 // Tell client to send next file
 982                                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
 983                                         return err
 984                                 }
 985                         } else {
 986                                 nextAction := dlFldrActionSendFile
 987
 988                                 // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
 989                                 _, err := os.Stat(dstPath + "/" + fu.FormattedPath())
 990                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
 991                                         return err
 992                                 }
 993                                 if err == nil {
 994                                         nextAction = dlFldrActionNextFile
 995                                 }
 996
 997                                 //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
 998                                 inccompleteFile, err := os.Stat(dstPath + "/" + fu.FormattedPath() + incompleteFileSuffix)
 999                                 if err != nil && !errors.Is(err, fs.ErrNotExist) {
1000                                         return err
1001                                 }
1002                                 if err == nil {
1003                                         nextAction = dlFldrActionResumeFile
1004                                 }
1005
1006                                 fmt.Printf("Next Action: %v\n", nextAction)
1007
1008                                 if _, err := conn.Write([]byte{0, uint8(nextAction)}); err != nil {
1009                                         return err
1010                                 }
1011
1012                                 switch nextAction {
1013                                 case dlFldrActionNextFile:
1014                                         continue
1015                                 case dlFldrActionResumeFile:
1016                                         offset := make([]byte, 4)
1017                                         binary.BigEndian.PutUint32(offset, uint32(inccompleteFile.Size()))
1018
1019                                         file, err := os.OpenFile(dstPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
1020                                         if err != nil {
1021                                                 return err
1022                                         }
1023
1024                                         fileResumeData := NewFileResumeData([]ForkInfoList{
1025                                                 *NewForkInfoList(offset),
1026                                         })
1027
1028                                         b, _ := fileResumeData.BinaryMarshal()
1029
1030                                         bs := make([]byte, 2)
1031                                         binary.BigEndian.PutUint16(bs, uint16(len(b)))
1032
1033                                         if _, err := conn.Write(append(bs, b...)); err != nil {
1034                                                 return err
1035                                         }
1036
1037                                         if _, err := conn.Read(fileSize); err != nil {
1038                                                 return err
1039                                         }
1040
1041                                         if err := receiveFile(conn, file, ioutil.Discard); err != nil {
1042                                                 s.Logger.Error(err)
1043                                         }
1044
1045                                         err = os.Rename(dstPath+"/"+fu.FormattedPath()+".incomplete", dstPath+"/"+fu.FormattedPath())
1046                                         if err != nil {
1047                                                 return err
1048                                         }
1049
1050                                 case dlFldrActionSendFile:
1051                                         if _, err := conn.Read(fileSize); err != nil {
1052                                                 return err
1053                                         }
1054
1055                                         filePath := dstPath + "/" + fu.FormattedPath()
1056                                         s.Logger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "totalFiles", "zz", "fileSize", binary.BigEndian.Uint32(fileSize))
1057
1058                                         newFile, err := FS.Create(filePath + ".incomplete")
1059                                         if err != nil {
1060                                                 return err
1061                                         }
1062
1063                                         if err := receiveFile(conn, newFile, ioutil.Discard); err != nil {
1064                                                 s.Logger.Error(err)
1065                                         }
1066                                         _ = newFile.Close()
1067                                         if err := os.Rename(filePath+".incomplete", filePath); err != nil {
1068                                                 return err
1069                                         }
1070                                 }
1071
1072                                 // Tell client to send next file
1073                                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
1074                                         return err
1075                                 }
1076                         }
1077                 }
1078                 s.Logger.Infof("Folder upload complete")
1079         }
1080
1081         return nil
1082 }
1083
1084 // sortedClients is a utility function that takes a map of *ClientConn and returns a sorted slice of the values.
1085 // The purpose of this is to ensure that the ordering of client connections is deterministic so that test assertions work.
1086 func sortedClients(unsortedClients map[uint16]*ClientConn) (clients []*ClientConn) {
1087         for _, c := range unsortedClients {
1088                 clients = append(clients, c)
1089         }
1090         sort.Sort(byClientID(clients))
1091         return clients
1092 }