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

   1 package hotline
   2
   3 import (
   4         "bytes"
   5         "context"
   6         "encoding/binary"
   7         "errors"
   8         "fmt"
   9         "go.uber.org/zap"
  10         "io"
  11         "io/ioutil"
  12         "log"
  13         "math/big"
  14         "math/rand"
  15         "net"
  16         "os"
  17         "path"
  18         "path/filepath"
  19         "runtime/debug"
  20         "sort"
  21         "strings"
  22         "sync"
  23         "time"
  24
  25         "golang.org/x/crypto/bcrypt"
  26         "gopkg.in/yaml.v2"
  27 )
  28
  29 const (
  30         userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
  31         idleCheckInterval      = 10  // time in seconds to check for idle users
  32         trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
  33 )
  34
  35 type Server struct {
  36         Interface     string
  37         Port          int
  38         Accounts      map[string]*Account
  39         Agreement     []byte
  40         Clients       map[uint16]*ClientConn
  41         FlatNews      []byte
  42         ThreadedNews  *ThreadedNews
  43         FileTransfers map[uint32]*FileTransfer
  44         Config        *Config
  45         ConfigDir     string
  46         Logger        *zap.SugaredLogger
  47         PrivateChats  map[uint32]*PrivateChat
  48         NextGuestID   *uint16
  49         TrackerPassID []byte
  50         Stats         *Stats
  51
  52         APIListener  net.Listener
  53         FileListener net.Listener
  54
  55         newsReader io.Reader
  56         newsWriter io.WriteCloser
  57
  58         outbox chan Transaction
  59
  60         mux         sync.Mutex
  61         flatNewsMux sync.Mutex
  62 }
  63
  64 type PrivateChat struct {
  65         Subject    string
  66         ClientConn map[uint16]*ClientConn
  67 }
  68
  69 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
  70         s.Logger.Infow("Hotline server started", "version", VERSION)
  71         var wg sync.WaitGroup
  72
  73         wg.Add(1)
  74         go func() { s.Logger.Fatal(s.Serve(ctx, cancelRoot, s.APIListener)) }()
  75
  76         wg.Add(1)
  77         go func() { s.Logger.Fatal(s.ServeFileTransfers(s.FileListener)) }()
  78
  79         wg.Wait()
  80
  81         return nil
  82 }
  83
  84 func (s *Server) APIPort() int {
  85         return s.APIListener.Addr().(*net.TCPAddr).Port
  86 }
  87
  88 func (s *Server) ServeFileTransfers(ln net.Listener) error {
  89         s.Logger.Infow("Hotline file transfer server started", "Addr", fmt.Sprintf(":%v", s.Port+1))
  90
  91         for {
  92                 conn, err := ln.Accept()
  93                 if err != nil {
  94                         return err
  95                 }
  96
  97                 go func() {
  98                         if err := s.TransferFile(conn); err != nil {
  99                                 s.Logger.Errorw("file transfer error", "reason", err)
 100                         }
 101                 }()
 102         }
 103 }
 104
 105 func (s *Server) sendTransaction(t Transaction) error {
 106         requestNum := binary.BigEndian.Uint16(t.Type)
 107         clientID, err := byteToInt(*t.clientID)
 108         if err != nil {
 109                 return err
 110         }
 111
 112         s.mux.Lock()
 113         client := s.Clients[uint16(clientID)]
 114         s.mux.Unlock()
 115         if client == nil {
 116                 return errors.New("invalid client")
 117         }
 118         userName := string(*client.UserName)
 119         login := client.Account.Login
 120
 121         handler := TransactionHandlers[requestNum]
 122
 123         var n int
 124         if n, err = client.Connection.Write(t.Payload()); err != nil {
 125                 return err
 126         }
 127         s.Logger.Debugw("Sent Transaction",
 128                 "name", userName,
 129                 "login", login,
 130                 "IsReply", t.IsReply,
 131                 "type", handler.Name,
 132                 "sentBytes", n,
 133                 "remoteAddr", client.Connection.RemoteAddr(),
 134         )
 135         return nil
 136 }
 137
 138 func (s *Server) Serve(ctx context.Context, cancelRoot context.CancelFunc, ln net.Listener) error {
 139         s.Logger.Infow("Hotline server started", "Addr", fmt.Sprintf(":%v", s.Port))
 140
 141         for {
 142                 conn, err := ln.Accept()
 143                 if err != nil {
 144                         s.Logger.Errorw("error accepting connection", "err", err)
 145                 }
 146
 147                 go func() {
 148                         for {
 149                                 t := <-s.outbox
 150                                 go func() {
 151                                         if err := s.sendTransaction(t); err != nil {
 152                                                 s.Logger.Errorw("error sending transaction", "err", err)
 153                                         }
 154                                 }()
 155                         }
 156                 }()
 157                 go func() {
 158                         if err := s.handleNewConnection(conn); err != nil {
 159                                 if err == io.EOF {
 160                                         s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 161                                 } else {
 162                                         s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 163                                 }
 164                         }
 165                 }()
 166         }
 167 }
 168
 169 const (
 170         agreementFile    = "Agreement.txt"
 171         messageBoardFile = "MessageBoard.txt"
 172         threadedNewsFile = "ThreadedNews.yaml"
 173 )
 174
 175 // NewServer constructs a new Server from a config dir
 176 func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredLogger) (*Server, error) {
 177         server := Server{
 178                 Port:          netPort,
 179                 Accounts:      make(map[string]*Account),
 180                 Config:        new(Config),
 181                 Clients:       make(map[uint16]*ClientConn),
 182                 FileTransfers: make(map[uint32]*FileTransfer),
 183                 PrivateChats:  make(map[uint32]*PrivateChat),
 184                 ConfigDir:     configDir,
 185                 Logger:        logger,
 186                 NextGuestID:   new(uint16),
 187                 outbox:        make(chan Transaction),
 188                 Stats:         &Stats{StartTime: time.Now()},
 189                 ThreadedNews:  &ThreadedNews{},
 190                 TrackerPassID: make([]byte, 4),
 191         }
 192
 193         ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
 194         if err != nil {
 195                 return nil, err
 196         }
 197         server.APIListener = ln
 198
 199         if netPort != 0 {
 200                 netPort += 1
 201         }
 202
 203         ln2, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
 204         server.FileListener = ln2
 205         if err != nil {
 206                 return nil, err
 207         }
 208
 209         // generate a new random passID for tracker registration
 210         if _, err := rand.Read(server.TrackerPassID); err != nil {
 211                 return nil, err
 212         }
 213
 214         server.Logger.Debugw("Loading Agreement", "path", configDir+agreementFile)
 215         if server.Agreement, err = os.ReadFile(configDir + agreementFile); err != nil {
 216                 return nil, err
 217         }
 218
 219         if server.FlatNews, err = os.ReadFile(configDir + "MessageBoard.txt"); err != nil {
 220                 return nil, err
 221         }
 222
 223         if err := server.loadThreadedNews(configDir + "ThreadedNews.yaml"); err != nil {
 224                 return nil, err
 225         }
 226
 227         if err := server.loadConfig(configDir + "config.yaml"); err != nil {
 228                 return nil, err
 229         }
 230
 231         if err := server.loadAccounts(configDir + "Users/"); err != nil {
 232                 return nil, err
 233         }
 234
 235         server.Config.FileRoot = configDir + "Files/"
 236
 237         *server.NextGuestID = 1
 238
 239         if server.Config.EnableTrackerRegistration {
 240                 go func() {
 241                         for {
 242                                 tr := TrackerRegistration{
 243                                         Port:        []byte{0x15, 0x7c},
 244                                         UserCount:   server.userCount(),
 245                                         PassID:      server.TrackerPassID,
 246                                         Name:        server.Config.Name,
 247                                         Description: server.Config.Description,
 248                                 }
 249                                 for _, t := range server.Config.Trackers {
 250                                         server.Logger.Infof("Registering with tracker %v", t)
 251
 252                                         if err := register(t, tr); err != nil {
 253                                                 server.Logger.Errorw("unable to register with tracker %v", "error", err)
 254                                         }
 255                                 }
 256
 257                                 time.Sleep(trackerUpdateFrequency * time.Second)
 258                         }
 259                 }()
 260         }
 261
 262         // Start Client Keepalive go routine
 263         go server.keepaliveHandler()
 264
 265         return &server, nil
 266 }
 267
 268 func (s *Server) userCount() int {
 269         s.mux.Lock()
 270         defer s.mux.Unlock()
 271
 272         return len(s.Clients)
 273 }
 274
 275 func (s *Server) keepaliveHandler() {
 276         for {
 277                 time.Sleep(idleCheckInterval * time.Second)
 278                 s.mux.Lock()
 279
 280                 for _, c := range s.Clients {
 281                         *c.IdleTime += idleCheckInterval
 282                         if *c.IdleTime > userIdleSeconds && !c.Idle {
 283                                 c.Idle = true
 284
 285                                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
 286                                 flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
 287                                 binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
 288
 289                                 c.sendAll(
 290                                         tranNotifyChangeUser,
 291                                         NewField(fieldUserID, *c.ID),
 292                                         NewField(fieldUserFlags, *c.Flags),
 293                                         NewField(fieldUserName, *c.UserName),
 294                                         NewField(fieldUserIconID, *c.Icon),
 295                                 )
 296                         }
 297                 }
 298                 s.mux.Unlock()
 299         }
 300 }
 301
 302 func (s *Server) writeThreadedNews() error {
 303         s.mux.Lock()
 304         defer s.mux.Unlock()
 305
 306         out, err := yaml.Marshal(s.ThreadedNews)
 307         if err != nil {
 308                 return err
 309         }
 310         err = ioutil.WriteFile(
 311                 s.ConfigDir+"ThreadedNews.yaml",
 312                 out,
 313                 0666,
 314         )
 315         return err
 316 }
 317
 318 func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
 319         s.mux.Lock()
 320         defer s.mux.Unlock()
 321
 322         clientConn := &ClientConn{
 323                 ID:         &[]byte{0, 0},
 324                 Icon:       &[]byte{0, 0},
 325                 Flags:      &[]byte{0, 0},
 326                 UserName:   &[]byte{},
 327                 Connection: conn,
 328                 Server:     s,
 329                 Version:    &[]byte{},
 330                 IdleTime:   new(int),
 331                 AutoReply:  &[]byte{},
 332                 Transfers:  make(map[int][]*FileTransfer),
 333         }
 334         *s.NextGuestID++
 335         ID := *s.NextGuestID
 336
 337         *clientConn.IdleTime = 0
 338
 339         binary.BigEndian.PutUint16(*clientConn.ID, ID)
 340         s.Clients[ID] = clientConn
 341
 342         return clientConn
 343 }
 344
 345 // NewUser creates a new user account entry in the server map and config file
 346 func (s *Server) NewUser(login, name, password string, access []byte) error {
 347         s.mux.Lock()
 348         defer s.mux.Unlock()
 349
 350         account := Account{
 351                 Login:    login,
 352                 Name:     name,
 353                 Password: hashAndSalt([]byte(password)),
 354                 Access:   &access,
 355         }
 356         out, err := yaml.Marshal(&account)
 357         if err != nil {
 358                 return err
 359         }
 360         s.Accounts[login] = &account
 361
 362         return ioutil.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
 363 }
 364
 365 // DeleteUser deletes the user account
 366 func (s *Server) DeleteUser(login string) error {
 367         s.mux.Lock()
 368         defer s.mux.Unlock()
 369
 370         delete(s.Accounts, login)
 371
 372         return os.Remove(s.ConfigDir + "Users/" + login + ".yaml")
 373 }
 374
 375 func (s *Server) connectedUsers() []Field {
 376         s.mux.Lock()
 377         defer s.mux.Unlock()
 378
 379         var connectedUsers []Field
 380         for _, c := range s.Clients {
 381                 user := User{
 382                         ID:    *c.ID,
 383                         Icon:  *c.Icon,
 384                         Flags: *c.Flags,
 385                         Name:  string(*c.UserName),
 386                 }
 387                 connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
 388         }
 389         return connectedUsers
 390 }
 391
 392 // loadThreadedNews loads the threaded news data from disk
 393 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
 394         fh, err := os.Open(threadedNewsPath)
 395         if err != nil {
 396                 return err
 397         }
 398         decoder := yaml.NewDecoder(fh)
 399         decoder.SetStrict(true)
 400
 401         return decoder.Decode(s.ThreadedNews)
 402 }
 403
 404 // loadAccounts loads account data from disk
 405 func (s *Server) loadAccounts(userDir string) error {
 406         matches, err := filepath.Glob(path.Join(userDir, "*.yaml"))
 407         if err != nil {
 408                 return err
 409         }
 410
 411         if len(matches) == 0 {
 412                 return errors.New("no user accounts found in " + userDir)
 413         }
 414
 415         for _, file := range matches {
 416                 fh, err := os.Open(file)
 417                 if err != nil {
 418                         return err
 419                 }
 420
 421                 account := Account{}
 422                 decoder := yaml.NewDecoder(fh)
 423                 decoder.SetStrict(true)
 424                 if err := decoder.Decode(&account); err != nil {
 425                         return err
 426                 }
 427
 428                 s.Accounts[account.Login] = &account
 429         }
 430         return nil
 431 }
 432
 433 func (s *Server) loadConfig(path string) error {
 434         fh, err := os.Open(path)
 435         if err != nil {
 436                 return err
 437         }
 438
 439         decoder := yaml.NewDecoder(fh)
 440         decoder.SetStrict(true)
 441         err = decoder.Decode(s.Config)
 442         if err != nil {
 443                 return err
 444         }
 445         return nil
 446 }
 447
 448 const (
 449         minTransactionLen = 22 // minimum length of any transaction
 450 )
 451
 452 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 453 func (s *Server) handleNewConnection(conn net.Conn) error {
 454         handshakeBuf := make([]byte, 12) // handshakes are always 12 bytes in length
 455         if _, err := conn.Read(handshakeBuf); err != nil {
 456                 return err
 457         }
 458         if err := Handshake(conn, handshakeBuf[:12]); err != nil {
 459                 return err
 460         }
 461
 462         buf := make([]byte, 1024)
 463         readLen, err := conn.Read(buf)
 464         if readLen < minTransactionLen {
 465                 return err
 466         }
 467         if err != nil {
 468                 return err
 469         }
 470
 471         clientLogin, _, err := ReadTransaction(buf[:readLen])
 472         if err != nil {
 473                 return err
 474         }
 475
 476         c := s.NewClientConn(conn)
 477         defer c.Disconnect()
 478         defer func() {
 479                 if r := recover(); r != nil {
 480                         fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
 481                         c.Server.Logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
 482                         c.Disconnect()
 483                 }
 484         }()
 485
 486         encodedLogin := clientLogin.GetField(fieldUserLogin).Data
 487         encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 488         *c.Version = clientLogin.GetField(fieldVersion).Data
 489
 490         var login string
 491         for _, char := range encodedLogin {
 492                 login += string(rune(255 - uint(char)))
 493         }
 494         if login == "" {
 495                 login = GuestAccount
 496         }
 497
 498         // If authentication fails, send error reply and close connection
 499         if !c.Authenticate(login, encodedPassword) {
 500                 rep := c.NewErrReply(clientLogin, "Incorrect login.")
 501                 if _, err := conn.Write(rep.Payload()); err != nil {
 502                         return err
 503                 }
 504                 return fmt.Errorf("incorrect login")
 505         }
 506
 507         // Hotline 1.2.3 client does not send fieldVersion
 508         // Nostalgia client sends ""
 509         //if string(*c.Version) == "" {
 510         //      *c.UserName = clientLogin.GetField(fieldUserName).Data
 511         //      *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 512         //}
 513         //
 514         if clientLogin.GetField(fieldUserName).Data != nil {
 515                 *c.UserName = clientLogin.GetField(fieldUserName).Data
 516         }
 517
 518         if clientLogin.GetField(fieldUserIconID).Data != nil {
 519                 *c.Icon = clientLogin.GetField(fieldUserIconID).Data
 520         }
 521
 522         c.Account = c.Server.Accounts[login]
 523
 524         if c.Authorize(accessDisconUser) {
 525                 *c.Flags = []byte{0, 2}
 526         }
 527
 528         s.Logger.Infow("Client connection received", "login", login, "version", *c.Version, "RemoteAddr", conn.RemoteAddr().String())
 529
 530         s.outbox <- c.NewReply(clientLogin,
 531                 NewField(fieldVersion, []byte{0x00, 0xbe}),
 532                 NewField(fieldCommunityBannerID, []byte{0x00, 0x01}),
 533                 NewField(fieldServerName, []byte(s.Config.Name)),
 534         )
 535
 536         // Send user access privs so client UI knows how to behave
 537         c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
 538
 539         // Show agreement to client
 540         c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
 541
 542         // The Hotline ClientConn v1.2.3 has a different login sequence than 1.9.2
 543         if string(*c.Version) == "" {
 544                 if _, err := c.notifyNewUserHasJoined(); err != nil {
 545                         return err
 546                 }
 547         }
 548
 549         if _, err := c.notifyNewUserHasJoined(); err != nil {
 550                 return err
 551         }
 552         c.Server.Stats.LoginCount += 1
 553
 554         const readBuffSize = 1024000 // 1KB - TODO: what should this be?
 555         const maxTranSize = 1024000
 556         tranBuff := make([]byte, 0)
 557         tReadlen := 0
 558         // Infinite loop where take action on incoming client requests until the connection is closed
 559         for {
 560                 buf = make([]byte, readBuffSize)
 561                 tranBuff = tranBuff[tReadlen:]
 562
 563                 readLen, err := c.Connection.Read(buf)
 564                 if err != nil {
 565                         return err
 566                 }
 567                 tranBuff = append(tranBuff, buf[:readLen]...)
 568
 569                 // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
 570                 // into a slice of transactions
 571                 var transactions []Transaction
 572                 if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
 573                         c.Server.Logger.Errorw("Error handling transaction", "err", err)
 574                 }
 575
 576                 // iterate over all of the transactions that were parsed from the byte slice and handle them
 577                 for _, t := range transactions {
 578                         if err := c.handleTransaction(&t); err != nil {
 579                                 c.Server.Logger.Errorw("Error handling transaction", "err", err)
 580                         }
 581                 }
 582         }
 583 }
 584
 585 func hashAndSalt(pwd []byte) string {
 586         // Use GenerateFromPassword to hash & salt pwd.
 587         // MinCost is just an integer constant provided by the bcrypt
 588         // package along with DefaultCost & MaxCost.
 589         // The cost can be any value you want provided it isn't lower
 590         // than the MinCost (4)
 591         hash, err := bcrypt.GenerateFromPassword(pwd, bcrypt.MinCost)
 592         if err != nil {
 593                 log.Println(err)
 594         }
 595         // GenerateFromPassword returns a byte slice so we need to
 596         // convert the bytes to a string and return it
 597         return string(hash)
 598 }
 599
 600 // NewTransactionRef generates a random ID for the file transfer.  The Hotline client includes this ID
 601 // in the file transfer request payload, and the file transfer server will use it to map the request
 602 // to a transfer
 603 func (s *Server) NewTransactionRef() []byte {
 604         transactionRef := make([]byte, 4)
 605         rand.Read(transactionRef)
 606
 607         return transactionRef
 608 }
 609
 610 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 611         s.mux.Lock()
 612         defer s.mux.Unlock()
 613
 614         randID := make([]byte, 4)
 615         rand.Read(randID)
 616         data := binary.BigEndian.Uint32(randID[:])
 617
 618         s.PrivateChats[data] = &PrivateChat{
 619                 Subject:    "",
 620                 ClientConn: make(map[uint16]*ClientConn),
 621         }
 622         s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
 623
 624         return randID
 625 }
 626
 627 const dlFldrActionSendFile = 1
 628 const dlFldrActionResumeFile = 2
 629 const dlFldrActionNextFile = 3
 630
 631 func (s *Server) TransferFile(conn net.Conn) error {
 632         defer func() { _ = conn.Close() }()
 633
 634         buf := make([]byte, 1024)
 635         if _, err := conn.Read(buf); err != nil {
 636                 return err
 637         }
 638
 639         t, err := NewReadTransfer(buf)
 640         if err != nil {
 641                 return err
 642         }
 643
 644         transferRefNum := binary.BigEndian.Uint32(t.ReferenceNumber[:])
 645         fileTransfer := s.FileTransfers[transferRefNum]
 646
 647         switch fileTransfer.Type {
 648         case FileDownload:
 649                 fullFilePath := fmt.Sprintf("%v/%v", s.Config.FileRoot+string(fileTransfer.FilePath), string(fileTransfer.FileName))
 650
 651                 ffo, err := NewFlattenedFileObject(
 652                         s.Config.FileRoot+string(fileTransfer.FilePath),
 653                         string(fileTransfer.FileName),
 654                 )
 655                 if err != nil {
 656                         return err
 657                 }
 658
 659                 s.Logger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber, "RemoteAddr", conn.RemoteAddr().String())
 660
 661                 // Start by sending flat file object to client
 662                 if _, err := conn.Write(ffo.Payload()); err != nil {
 663                         return err
 664                 }
 665
 666                 file, err := os.Open(fullFilePath)
 667                 if err != nil {
 668                         return err
 669                 }
 670
 671                 sendBuffer := make([]byte, 1048576)
 672                 for {
 673                         var bytesRead int
 674                         if bytesRead, err = file.Read(sendBuffer); err == io.EOF {
 675                                 break
 676                         }
 677
 678                         fileTransfer.BytesSent += bytesRead
 679
 680                         delete(s.FileTransfers, transferRefNum)
 681
 682                         if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
 683                                 return err
 684                         }
 685                 }
 686         case FileUpload:
 687                 if _, err := conn.Read(buf); err != nil {
 688                         return err
 689                 }
 690
 691                 ffo := ReadFlattenedFileObject(buf)
 692                 payloadLen := len(ffo.Payload())
 693                 fileSize := int(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize))
 694
 695                 destinationFile := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
 696                 s.Logger.Infow(
 697                         "File upload started",
 698                         "transactionRef", fileTransfer.ReferenceNumber,
 699                         "RemoteAddr", conn.RemoteAddr().String(),
 700                         "size", fileSize,
 701                         "dstFile", destinationFile,
 702                 )
 703
 704                 newFile, err := os.Create(destinationFile)
 705                 if err != nil {
 706                         return err
 707                 }
 708
 709                 defer func() { _ = newFile.Close() }()
 710
 711                 const buffSize = 1024
 712
 713                 if _, err := newFile.Write(buf[payloadLen:]); err != nil {
 714                         return err
 715                 }
 716                 receivedBytes := buffSize - payloadLen
 717
 718                 for {
 719                         if (fileSize - receivedBytes) < buffSize {
 720                                 s.Logger.Infow(
 721                                         "File upload complete",
 722                                         "transactionRef", fileTransfer.ReferenceNumber,
 723                                         "RemoteAddr", conn.RemoteAddr().String(),
 724                                         "size", fileSize,
 725                                         "dstFile", destinationFile,
 726                                 )
 727
 728                                 if _, err := io.CopyN(newFile, conn, int64(fileSize-receivedBytes)); err != nil {
 729                                         return fmt.Errorf("file transfer failed: %s", err)
 730                                 }
 731                                 return nil
 732                         }
 733
 734                         // Copy N bytes from conn to upload file
 735                         n, err := io.CopyN(newFile, conn, buffSize)
 736                         if err != nil {
 737                                 return err
 738                         }
 739                         receivedBytes += int(n)
 740                 }
 741         case FolderDownload:
 742                 // Folder Download flow:
 743                 // 1. Get filePath from the Transfer
 744                 // 2. Iterate over files
 745                 // 3. For each file:
 746                 //       Send file header to client
 747                 // The client can reply in 3 ways:
 748                 //
 749                 // 1. If type is an odd number (unknown type?), or file download for the current file is completed:
 750                 //              client sends []byte{0x00, 0x03} to tell the server to continue to the next file
 751                 //
 752                 // 2. If download of a file is to be resumed:
 753                 //              client sends:
 754                 //                      []byte{0x00, 0x02} // download folder action
 755                 //                      [2]byte // Resume data size
 756                 //                      []byte file resume data (see myField_FileResumeData)
 757                 //
 758                 // 3. Otherwise download of the file is requested and client sends []byte{0x00, 0x01}
 759                 //
 760                 // When download is requested (case 2 or 3), server replies with:
 761                 //                      [4]byte - file size
 762                 //                      []byte  - Flattened File Object
 763                 //
 764                 // After every file download, client could request next file with:
 765                 //                      []byte{0x00, 0x03}
 766                 //
 767                 // This notifies the server to send the next item header
 768
 769                 fh := NewFilePath(fileTransfer.FilePath)
 770                 fullFilePath := fmt.Sprintf("%v/%v", s.Config.FileRoot+fh.String(), string(fileTransfer.FileName))
 771
 772                 basePathLen := len(fullFilePath)
 773
 774                 readBuffer := make([]byte, 1024)
 775
 776                 s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber, "RemoteAddr", conn.RemoteAddr())
 777
 778                 i := 0
 779                 _ = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, _ error) error {
 780                         i += 1
 781                         subPath := path[basePathLen-2:]
 782                         s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())
 783
 784                         fileHeader := NewFileHeader(subPath, info.IsDir())
 785
 786                         if i == 1 {
 787                                 return nil
 788                         }
 789
 790                         // Send the file header to client
 791                         if _, err := conn.Write(fileHeader.Payload()); err != nil {
 792                                 s.Logger.Errorf("error sending file header: %v", err)
 793                                 return err
 794                         }
 795
 796                         // Read the client's Next Action request
 797                         //TODO: Remove hardcoded behavior and switch behaviors based on the next action send
 798                         if _, err := conn.Read(readBuffer); err != nil {
 799                                 s.Logger.Errorf("error reading next action: %v", err)
 800                                 return err
 801                         }
 802
 803                         s.Logger.Infow("Client folder download action", "action", fmt.Sprintf("%X", readBuffer[0:2]))
 804
 805                         if info.IsDir() {
 806                                 return nil
 807                         }
 808
 809                         splitPath := strings.Split(path, "/")
 810                         //strings.Join(splitPath[:len(splitPath)-1], "/")
 811
 812                         ffo, err := NewFlattenedFileObject(strings.Join(splitPath[:len(splitPath)-1], "/"), info.Name())
 813                         if err != nil {
 814                                 return err
 815                         }
 816                         s.Logger.Infow("File download started",
 817                                 "fileName", info.Name(),
 818                                 "transactionRef", fileTransfer.ReferenceNumber,
 819                                 "RemoteAddr", conn.RemoteAddr().String(),
 820                                 "TransferSize", fmt.Sprintf("%x", ffo.TransferSize()),
 821                         )
 822
 823                         // Send file size to client
 824                         if _, err := conn.Write(ffo.TransferSize()); err != nil {
 825                                 s.Logger.Error(err)
 826                                 return err
 827                         }
 828
 829                         // Send file bytes to client
 830                         if _, err := conn.Write(ffo.Payload()); err != nil {
 831                                 s.Logger.Error(err)
 832                                 return err
 833                         }
 834
 835                         file, err := os.Open(path)
 836                         if err != nil {
 837                                 return err
 838                         }
 839
 840                         sendBuffer := make([]byte, 1048576)
 841                         totalBytesSent := len(ffo.Payload())
 842
 843                         for {
 844                                 bytesRead, err := file.Read(sendBuffer)
 845                                 if err == io.EOF {
 846                                         // Read the client's Next Action request
 847                                         //TODO: Remove hardcoded behavior and switch behaviors based on the next action send
 848                                         if _, err := conn.Read(readBuffer); err != nil {
 849                                                 s.Logger.Errorf("error reading next action: %v", err)
 850                                                 return err
 851                                         }
 852                                         break
 853                                 }
 854
 855                                 sentBytes, readErr := conn.Write(sendBuffer[:bytesRead])
 856                                 totalBytesSent += sentBytes
 857                                 if readErr != nil {
 858                                         return err
 859                                 }
 860                         }
 861                         return nil
 862                 })
 863
 864         case FolderUpload:
 865                 dstPath := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
 866                 s.Logger.Infow(
 867                         "Folder upload started",
 868                         "transactionRef", fileTransfer.ReferenceNumber,
 869                         "RemoteAddr", conn.RemoteAddr().String(),
 870                         "dstPath", dstPath,
 871                         "TransferSize", fileTransfer.TransferSize,
 872                         "FolderItemCount", fileTransfer.FolderItemCount,
 873                 )
 874
 875                 // Check if the target folder exists.  If not, create it.
 876                 if _, err := os.Stat(dstPath); os.IsNotExist(err) {
 877                         s.Logger.Infow("Target path does not exist; Creating...", "dstPath", dstPath)
 878                         if err := os.Mkdir(dstPath, 0777); err != nil {
 879                                 s.Logger.Error(err)
 880                         }
 881                 }
 882
 883                 readBuffer := make([]byte, 1024)
 884
 885                 // Begin the folder upload flow by sending the "next file action" to client
 886                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
 887                         return err
 888                 }
 889
 890                 fileSize := make([]byte, 4)
 891                 itemCount := binary.BigEndian.Uint16(fileTransfer.FolderItemCount)
 892
 893                 for i := uint16(0); i < itemCount; i++ {
 894                         if _, err := conn.Read(readBuffer); err != nil {
 895                                 return err
 896                         }
 897                         fu := readFolderUpload(readBuffer)
 898
 899                         s.Logger.Infow(
 900                                 "Folder upload continued",
 901                                 "transactionRef", fmt.Sprintf("%x", fileTransfer.ReferenceNumber),
 902                                 "RemoteAddr", conn.RemoteAddr().String(),
 903                                 "FormattedPath", fu.FormattedPath(),
 904                                 "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
 905                                 "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount),
 906                         )
 907
 908                         if bytes.Equal(fu.IsFolder, []byte{0, 1}) {
 909                                 if _, err := os.Stat(dstPath + "/" + fu.FormattedPath()); os.IsNotExist(err) {
 910                                         s.Logger.Infow("Target path does not exist; Creating...", "dstPath", dstPath)
 911                                         if err := os.Mkdir(dstPath+"/"+fu.FormattedPath(), 0777); err != nil {
 912                                                 s.Logger.Error(err)
 913                                         }
 914                                 }
 915
 916                                 // Tell client to send next file
 917                                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
 918                                         s.Logger.Error(err)
 919                                         return err
 920                                 }
 921                         } else {
 922                                 // TODO: Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
 923                                 // TODO: Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
 924                                 // Send dlFldrAction_SendFile to client to begin transfer
 925                                 if _, err := conn.Write([]byte{0, dlFldrActionSendFile}); err != nil {
 926                                         return err
 927                                 }
 928
 929                                 if _, err := conn.Read(fileSize); err != nil {
 930                                         fmt.Println("Error reading:", err.Error()) // TODO: handle
 931                                 }
 932
 933                                 s.Logger.Infow("Starting file transfer", "fileNum", i+1, "totalFiles", itemCount, "fileSize", fileSize)
 934
 935                                 if err := transferFile(conn, dstPath+"/"+fu.FormattedPath()); err != nil {
 936                                         s.Logger.Error(err)
 937                                 }
 938
 939                                 // Tell client to send next file
 940                                 if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
 941                                         s.Logger.Error(err)
 942                                         return err
 943                                 }
 944
 945                                 // Client sends "MACR" after the file.  Read and discard.
 946                                 // TODO: This doesn't seem to be documented.  What is this?  Maybe resource fork?
 947                                 if _, err := conn.Read(readBuffer); err != nil {
 948                                         return err
 949                                 }
 950                         }
 951                 }
 952                 s.Logger.Infof("Folder upload complete")
 953         }
 954
 955         return nil
 956 }
 957
 958 func transferFile(conn net.Conn, dst string) error {
 959         const buffSize = 1024
 960         buf := make([]byte, buffSize)
 961
 962         // Read first chunk of bytes from conn; this will be the Flat File Object and initial chunk of file bytes
 963         if _, err := conn.Read(buf); err != nil {
 964                 return err
 965         }
 966         ffo := ReadFlattenedFileObject(buf)
 967         payloadLen := len(ffo.Payload())
 968         fileSize := int(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize))
 969
 970         newFile, err := os.Create(dst)
 971         if err != nil {
 972                 return err
 973         }
 974         defer func() { _ = newFile.Close() }()
 975         if _, err := newFile.Write(buf[payloadLen:]); err != nil {
 976                 return err
 977         }
 978         receivedBytes := buffSize - payloadLen
 979
 980         for {
 981                 if (fileSize - receivedBytes) < buffSize {
 982                         _, err := io.CopyN(newFile, conn, int64(fileSize-receivedBytes))
 983                         return err
 984                 }
 985
 986                 // Copy N bytes from conn to upload file
 987                 n, err := io.CopyN(newFile, conn, buffSize)
 988                 if err != nil {
 989                         return err
 990                 }
 991                 receivedBytes += int(n)
 992         }
 993 }
 994
 995 // 00 28 // DataSize
 996 // 00 00 // IsFolder
 997 // 00 02 // PathItemCount
 998 //
 999 // 00 00
1000 // 09
1001 // 73 75 62 66 6f 6c 64 65 72 // "subfolder"
1002 //
1003 // 00 00
1004 // 15
1005 // 73 75 62 66 6f 6c 64 65 72 2d 74 65 73 74 66 69 6c 65 2d 35 6b // "subfolder-testfile-5k"
1006 func readFolderUpload(buf []byte) folderUpload {
1007         dataLen := binary.BigEndian.Uint16(buf[0:2])
1008
1009         fu := folderUpload{
1010                 DataSize:      buf[0:2], // Size of this structure (not including data size element itself)
1011                 IsFolder:      buf[2:4],
1012                 PathItemCount: buf[4:6],
1013                 FileNamePath:  buf[6 : dataLen+2],
1014         }
1015
1016         return fu
1017 }
1018
1019 type folderUpload struct {
1020         DataSize      []byte
1021         IsFolder      []byte
1022         PathItemCount []byte
1023         FileNamePath  []byte
1024 }
1025
1026 func (fu *folderUpload) FormattedPath() string {
1027         pathItemLen := binary.BigEndian.Uint16(fu.PathItemCount)
1028
1029         var pathSegments []string
1030         pathData := fu.FileNamePath
1031
1032         for i := uint16(0); i < pathItemLen; i++ {
1033                 segLen := pathData[2]
1034                 pathSegments = append(pathSegments, string(pathData[3:3+segLen]))
1035                 pathData = pathData[3+segLen:]
1036         }
1037
1038         return strings.Join(pathSegments, pathSeparator)
1039 }
1040
1041 // sortedClients is a utility function that takes a map of *ClientConn and returns a sorted slice of the values.
1042 // The purpose of this is to ensure that the ordering of client connections is deterministic so that test assertions work.
1043 func sortedClients(unsortedClients map[uint16]*ClientConn) (clients []*ClientConn) {
1044         for _, c := range unsortedClients {
1045                 clients = append(clients, c)
1046         }
1047         sort.Sort(byClientID(clients))
1048         return clients
1049 }