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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "bytes"
   6         "context"
   7         "crypto/rand"
   8         "encoding/binary"
   9         "errors"
  10         "fmt"
  11         "golang.org/x/text/encoding/charmap"
  12         "io"
  13         "log"
  14         "log/slog"
  15         "net"
  16         "os"
  17         "strings"
  18         "sync"
  19         "time"
  20 )
  21
  22 type contextKey string
  23
  24 var contextKeyReq = contextKey("req")
  25
  26 type requestCtx struct {
  27         remoteAddr string
  28 }
  29
  30 // Converts bytes from Mac Roman encoding to UTF-8
  31 var txtDecoder = charmap.Macintosh.NewDecoder()
  32
  33 // Converts bytes from UTF-8 to Mac Roman encoding
  34 var txtEncoder = charmap.Macintosh.NewEncoder()
  35
  36 type Server struct {
  37         NetInterface string
  38         Port         int
  39
  40         handlers map[TranType]HandlerFunc
  41
  42         Config Config
  43         Logger *slog.Logger
  44
  45         TrackerPassID [4]byte
  46
  47         Stats Counter
  48
  49         FS FileStore // Storage backend to use for File storage
  50
  51         outbox chan Transaction
  52
  53         Agreement io.ReadSeeker
  54         Banner    []byte
  55
  56         FileTransferMgr FileTransferMgr
  57         ChatMgr         ChatManager
  58         ClientMgr       ClientManager
  59         AccountManager  AccountManager
  60         ThreadedNewsMgr ThreadedNewsMgr
  61         BanList         BanMgr
  62
  63         MessageBoard io.ReadWriteSeeker
  64 }
  65
  66 type Option = func(s *Server)
  67
  68 func WithConfig(config Config) func(s *Server) {
  69         return func(s *Server) {
  70                 s.Config = config
  71         }
  72 }
  73
  74 func WithLogger(logger *slog.Logger) func(s *Server) {
  75         return func(s *Server) {
  76                 s.Logger = logger
  77         }
  78 }
  79
  80 // WithPort optionally overrides the default TCP port.
  81 func WithPort(port int) func(s *Server) {
  82         return func(s *Server) {
  83                 s.Port = port
  84         }
  85 }
  86
  87 // WithInterface optionally sets a specific interface to listen on.
  88 func WithInterface(netInterface string) func(s *Server) {
  89         return func(s *Server) {
  90                 s.NetInterface = netInterface
  91         }
  92 }
  93
  94 type ServerConfig struct {
  95 }
  96
  97 func NewServer(options ...Option) (*Server, error) {
  98         server := Server{
  99                 handlers:        make(map[TranType]HandlerFunc),
 100                 outbox:          make(chan Transaction),
 101                 FS:              &OSFileStore{},
 102                 ChatMgr:         NewMemChatManager(),
 103                 ClientMgr:       NewMemClientMgr(),
 104                 FileTransferMgr: NewMemFileTransferMgr(),
 105                 Stats:           NewStats(),
 106         }
 107
 108         for _, opt := range options {
 109                 opt(&server)
 110         }
 111
 112         // generate a new random passID for tracker registration
 113         _, err := rand.Read(server.TrackerPassID[:])
 114         if err != nil {
 115                 return nil, err
 116         }
 117
 118         return &server, nil
 119 }
 120
 121 func (s *Server) CurrentStats() map[string]interface{} {
 122         return s.Stats.Values()
 123 }
 124
 125 func (s *Server) ListenAndServe(ctx context.Context) error {
 126         go s.registerWithTrackers(ctx)
 127         go s.keepaliveHandler(ctx)
 128         go s.processOutbox()
 129
 130         var wg sync.WaitGroup
 131
 132         wg.Add(1)
 133         go func() {
 134                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
 135                 if err != nil {
 136                         log.Fatal(err)
 137                 }
 138
 139                 log.Fatal(s.Serve(ctx, ln))
 140         }()
 141
 142         wg.Add(1)
 143         go func() {
 144                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
 145                 if err != nil {
 146                         log.Fatal(err)
 147                 }
 148
 149                 log.Fatal(s.ServeFileTransfers(ctx, ln))
 150         }()
 151
 152         wg.Wait()
 153
 154         return nil
 155 }
 156
 157 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 158         for {
 159                 conn, err := ln.Accept()
 160                 if err != nil {
 161                         return err
 162                 }
 163
 164                 go func() {
 165                         defer func() { _ = conn.Close() }()
 166
 167                         err = s.handleFileTransfer(
 168                                 context.WithValue(ctx, contextKeyReq, requestCtx{remoteAddr: conn.RemoteAddr().String()}),
 169                                 conn,
 170                         )
 171
 172                         if err != nil {
 173                                 s.Logger.Error("file transfer error", "reason", err)
 174                         }
 175                 }()
 176         }
 177 }
 178
 179 func (s *Server) sendTransaction(t Transaction) error {
 180         client := s.ClientMgr.Get(t.ClientID)
 181
 182         if client == nil {
 183                 return nil
 184         }
 185
 186         _, err := io.Copy(client.Connection, &t)
 187         if err != nil {
 188                 return fmt.Errorf("failed to send transaction to client %v: %v", t.ClientID, err)
 189         }
 190
 191         return nil
 192 }
 193
 194 func (s *Server) processOutbox() {
 195         for {
 196                 t := <-s.outbox
 197                 go func() {
 198                         if err := s.sendTransaction(t); err != nil {
 199                                 s.Logger.Error("error sending transaction", "err", err)
 200                         }
 201                 }()
 202         }
 203 }
 204
 205 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 206         for {
 207                 select {
 208                 case <-ctx.Done():
 209                         s.Logger.Info("Server shutting down")
 210                         return ctx.Err()
 211                 default:
 212                         conn, err := ln.Accept()
 213                         if err != nil {
 214                                 s.Logger.Error("Error accepting connection", "err", err)
 215                                 continue
 216                         }
 217
 218                         go func() {
 219                                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 220                                         remoteAddr: conn.RemoteAddr().String(),
 221                                 })
 222
 223                                 s.Logger.Info("Connection established", "addr", conn.RemoteAddr())
 224                                 defer conn.Close()
 225
 226                                 if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 227                                         if err == io.EOF {
 228                                                 s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 229                                         } else {
 230                                                 s.Logger.Error("Error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 231                                         }
 232                                 }
 233                         }()
 234                 }
 235         }
 236 }
 237
 238 // time in seconds between tracker re-registration
 239 const trackerUpdateFrequency = 300
 240
 241 // registerWithTrackers runs every trackerUpdateFrequency seconds to update the server's tracker entry on all configured
 242 // trackers.
 243 func (s *Server) registerWithTrackers(ctx context.Context) {
 244         ticker := time.NewTicker(trackerUpdateFrequency * time.Second)
 245         defer ticker.Stop()
 246
 247         for {
 248                 select {
 249                 case <-ctx.Done():
 250                         return
 251                 case <-ticker.C:
 252                         if s.Config.EnableTrackerRegistration {
 253                                 tr := &TrackerRegistration{
 254                                         UserCount:   len(s.ClientMgr.List()),
 255                                         PassID:      s.TrackerPassID,
 256                                         Name:        s.Config.Name,
 257                                         Description: s.Config.Description,
 258                                 }
 259                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
 260
 261                                 for _, t := range s.Config.Trackers {
 262                                         if err := register(&RealDialer{}, t, tr); err != nil {
 263                                                 s.Logger.Error(fmt.Sprintf("Unable to register with tracker %v", t), "error", err)
 264                                         }
 265                                 }
 266                         }
 267                 }
 268         }
 269
 270 }
 271
 272 const (
 273         userIdleSeconds   = 300 // time in seconds before an inactive user is marked idle
 274         idleCheckInterval = 10  // time in seconds to check for idle users
 275 )
 276
 277 // keepaliveHandler runs every idleCheckInterval seconds and increments a user's idle time by idleCheckInterval seconds.
 278 // If the updated idle time exceeds userIdleSeconds and the user was not previously idle, we notify all connected clients
 279 // that the user has gone idle.  For most clients, this turns the user grey in the user list.
 280 func (s *Server) keepaliveHandler(ctx context.Context) {
 281         ticker := time.NewTicker(idleCheckInterval * time.Second)
 282         defer ticker.Stop()
 283
 284         for {
 285                 select {
 286                 case <-ctx.Done():
 287                         return
 288                 case <-ticker.C:
 289                         for _, c := range s.ClientMgr.List() {
 290                                 c.mu.Lock()
 291                                 c.IdleTime += idleCheckInterval
 292
 293                                 // Check if the user
 294                                 if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
 295                                         c.Flags.Set(UserFlagAway, 1)
 296
 297                                         c.SendAll(
 298                                                 TranNotifyChangeUser,
 299                                                 NewField(FieldUserID, c.ID[:]),
 300                                                 NewField(FieldUserFlags, c.Flags[:]),
 301                                                 NewField(FieldUserName, c.UserName),
 302                                                 NewField(FieldUserIconID, c.Icon),
 303                                         )
 304                                 }
 305                                 c.mu.Unlock()
 306                         }
 307                 }
 308         }
 309 }
 310
 311 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 312         clientConn := &ClientConn{
 313                 Icon:       []byte{0, 0}, // TODO: make array type
 314                 Connection: conn,
 315                 Server:     s,
 316                 RemoteAddr: remoteAddr,
 317
 318                 ClientFileTransferMgr: NewClientFileTransferMgr(),
 319         }
 320
 321         s.ClientMgr.Add(clientConn)
 322
 323         return clientConn
 324 }
 325
 326 func sendBanMessage(rwc io.Writer, message string) {
 327         t := NewTransaction(
 328                 TranServerMsg,
 329                 [2]byte{0, 0},
 330                 NewField(FieldData, []byte(message)),
 331                 NewField(FieldChatOptions, []byte{0, 0}),
 332         )
 333         _, _ = io.Copy(rwc, &t)
 334         time.Sleep(1 * time.Second)
 335 }
 336
 337 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 338 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 339         defer dontPanic(s.Logger)
 340
 341         if err := performHandshake(rwc); err != nil {
 342                 return fmt.Errorf("perform handshake: %w", err)
 343         }
 344
 345         // Check if remoteAddr is present in the ban list
 346         ipAddr := strings.Split(remoteAddr, ":")[0]
 347         if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
 348                 // permaban
 349                 if banUntil == nil {
 350                         sendBanMessage(rwc, "You are permanently banned on this server")
 351                         s.Logger.Debug("Disconnecting permanently banned IP", "remoteAddr", ipAddr)
 352                         return nil
 353                 }
 354
 355                 // temporary ban
 356                 if time.Now().Before(*banUntil) {
 357                         sendBanMessage(rwc, "You are temporarily banned on this server")
 358                         s.Logger.Debug("Disconnecting temporarily banned IP", "remoteAddr", ipAddr)
 359                         return nil
 360                 }
 361         }
 362
 363         // Create a new scanner for parsing incoming bytes into transaction tokens
 364         scanner := bufio.NewScanner(rwc)
 365         scanner.Split(transactionScanner)
 366
 367         scanner.Scan()
 368
 369         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 370         // scanner re-uses the buffer for subsequent scans.
 371         buf := make([]byte, len(scanner.Bytes()))
 372         copy(buf, scanner.Bytes())
 373
 374         var clientLogin Transaction
 375         if _, err := clientLogin.Write(buf); err != nil {
 376                 return fmt.Errorf("error writing login transaction: %w", err)
 377         }
 378
 379         c := s.NewClientConn(rwc, remoteAddr)
 380         defer c.Disconnect()
 381
 382         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 383         c.Version = clientLogin.GetField(FieldVersion).Data
 384
 385         login := clientLogin.GetField(FieldUserLogin).DecodeObfuscatedString()
 386         if login == "" {
 387                 login = GuestAccount
 388         }
 389
 390         c.Logger = s.Logger.With("ip", ipAddr, "login", login)
 391
 392         // If authentication fails, send error reply and close connection
 393         if !c.Authenticate(login, encodedPassword) {
 394                 t := c.NewErrReply(&clientLogin, "Incorrect login.")[0]
 395
 396                 _, err := io.Copy(rwc, &t)
 397                 if err != nil {
 398                         return err
 399                 }
 400
 401                 c.Logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 402
 403                 return nil
 404         }
 405
 406         if clientLogin.GetField(FieldUserIconID).Data != nil {
 407                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 408         }
 409
 410         c.Account = c.Server.AccountManager.Get(login)
 411         if c.Account == nil {
 412                 return nil
 413         }
 414
 415         if clientLogin.GetField(FieldUserName).Data != nil {
 416                 if c.Authorize(AccessAnyName) {
 417                         c.UserName = clientLogin.GetField(FieldUserName).Data
 418                 } else {
 419                         c.UserName = []byte(c.Account.Name)
 420                 }
 421         }
 422
 423         if c.Authorize(AccessDisconUser) {
 424                 c.Flags.Set(UserFlagAdmin, 1)
 425         }
 426
 427         s.outbox <- c.NewReply(&clientLogin,
 428                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 429                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 430                 NewField(FieldServerName, []byte(s.Config.Name)),
 431         )
 432
 433         // Send user access privs so client UI knows how to behave
 434         c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 435
 436         // Accounts with AccessNoAgreement do not receive the server agreement on login.  The behavior is different between
 437         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 438         // TranShowAgreement but with the NoServerAgreement field set to 1.
 439         if c.Authorize(AccessNoAgreement) {
 440                 // If client version is nil, then the client uses the 1.2.3 login behavior
 441                 if c.Version != nil {
 442                         c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 443                 }
 444         } else {
 445                 _, _ = c.Server.Agreement.Seek(0, 0)
 446                 data, _ := io.ReadAll(c.Server.Agreement)
 447
 448                 c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, data))
 449         }
 450
 451         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 452         // flow and not the 1.5+ flow.
 453         if len(c.UserName) != 0 {
 454                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 455                 // part of TranAgreed
 456                 c.Logger = c.Logger.With("name", string(c.UserName))
 457                 c.Logger.Info("Login successful")
 458
 459                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 460                 // information yet, so we do it in TranAgreed instead
 461                 for _, t := range c.NotifyOthers(
 462                         NewTransaction(
 463                                 TranNotifyChangeUser, [2]byte{0, 0},
 464                                 NewField(FieldUserName, c.UserName),
 465                                 NewField(FieldUserID, c.ID[:]),
 466                                 NewField(FieldUserIconID, c.Icon),
 467                                 NewField(FieldUserFlags, c.Flags[:]),
 468                         ),
 469                 ) {
 470                         c.Server.outbox <- t
 471                 }
 472         }
 473
 474         c.Server.Stats.Increment(StatConnectionCounter, StatCurrentlyConnected)
 475         defer c.Server.Stats.Decrement(StatCurrentlyConnected)
 476
 477         if len(s.ClientMgr.List()) > c.Server.Stats.Get(StatConnectionPeak) {
 478                 c.Server.Stats.Set(StatConnectionPeak, len(s.ClientMgr.List()))
 479         }
 480
 481         // Scan for new transactions and handle them as they come in.
 482         for scanner.Scan() {
 483                 // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
 484                 tmpBuf := make([]byte, len(scanner.Bytes()))
 485                 copy(tmpBuf, scanner.Bytes())
 486
 487                 var t Transaction
 488                 if _, err := t.Write(tmpBuf); err != nil {
 489                         return err
 490                 }
 491
 492                 c.handleTransaction(t)
 493         }
 494         return nil
 495 }
 496
 497 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 498 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 499         defer dontPanic(s.Logger)
 500
 501         // The first 16 bytes contain the file transfer.
 502         var t transfer
 503         if _, err := io.CopyN(&t, rwc, 16); err != nil {
 504                 return fmt.Errorf("error reading file transfer: %w", err)
 505         }
 506
 507         fileTransfer := s.FileTransferMgr.Get(t.ReferenceNumber)
 508         if fileTransfer == nil {
 509                 return errors.New("invalid transaction ID")
 510         }
 511
 512         defer func() {
 513                 s.FileTransferMgr.Delete(t.ReferenceNumber)
 514
 515                 // Wait a few seconds before closing the connection: this is a workaround for problems
 516                 // observed with Windows clients where the client must initiate close of the TCP connection before
 517                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 518                 time.Sleep(3 * time.Second)
 519         }()
 520
 521         rLogger := s.Logger.With(
 522                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 523                 "login", fileTransfer.ClientConn.Account.Login,
 524                 "Name", string(fileTransfer.ClientConn.UserName),
 525         )
 526
 527         fullPath, err := ReadPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 528         if err != nil {
 529                 return err
 530         }
 531
 532         switch fileTransfer.Type {
 533         case BannerDownload:
 534                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.Banner)); err != nil {
 535                         return fmt.Errorf("error sending Banner: %w", err)
 536                 }
 537         case FileDownload:
 538                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 539                 defer func() {
 540                         s.Stats.Decrement(StatDownloadsInProgress)
 541                 }()
 542
 543                 err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
 544                 if err != nil {
 545                         return fmt.Errorf("file download: %w", err)
 546                 }
 547
 548         case FileUpload:
 549                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 550                 defer func() {
 551                         s.Stats.Decrement(StatUploadsInProgress)
 552                 }()
 553
 554                 err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 555                 if err != nil {
 556                         return fmt.Errorf("file upload error: %w", err)
 557                 }
 558
 559         case FolderDownload:
 560                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 561                 defer func() {
 562                         s.Stats.Decrement(StatDownloadsInProgress)
 563                 }()
 564
 565                 err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 566                 if err != nil {
 567                         return fmt.Errorf("file upload error: %w", err)
 568                 }
 569
 570         case FolderUpload:
 571                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 572                 defer func() {
 573                         s.Stats.Decrement(StatUploadsInProgress)
 574                 }()
 575
 576                 rLogger.Info(
 577                         "Folder upload started",
 578                         "dstPath", fullPath,
 579                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
 580                         "FolderItemCount", fileTransfer.FolderItemCount,
 581                 )
 582
 583                 err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 584                 if err != nil {
 585                         return fmt.Errorf("file upload error: %w", err)
 586                 }
 587         }
 588         return nil
 589 }
 590
 591 func (s *Server) SendAll(t TranType, fields ...Field) {
 592         for _, c := range s.ClientMgr.List() {
 593                 s.outbox <- NewTransaction(t, c.ID, fields...)
 594         }
 595 }
 596
 597 func (s *Server) Shutdown(msg []byte) {
 598         s.Logger.Info("Shutdown signal received")
 599         s.SendAll(TranDisconnectMsg, NewField(FieldData, msg))
 600
 601         time.Sleep(3 * time.Second)
 602
 603         os.Exit(0)
 604 }