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         for {
 245                 if s.Config.EnableTrackerRegistration {
 246                         for _, t := range s.Config.Trackers {
 247                                 tr := &TrackerRegistration{
 248                                         UserCount:   len(s.ClientMgr.List()),
 249                                         PassID:      s.TrackerPassID,
 250                                         Name:        s.Config.Name,
 251                                         Description: s.Config.Description,
 252                                 }
 253                                 binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
 254
 255                                 // Check the tracker string for a password.  This is janky but avoids a breaking change to the Config
 256                                 // Trackers field.
 257                                 splitAddr := strings.Split(":", t)
 258                                 if len(splitAddr) == 3 {
 259                                         tr.Password = splitAddr[2]
 260                                 }
 261
 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                 // Using time.Ticker with for/select would be more idiomatic, but it's super annoying that it doesn't tick on
 268                 // first pass.  Revist, maybe.
 269                 // https://github.com/golang/go/issues/17601
 270                 time.Sleep(trackerUpdateFrequency * time.Second)
 271         }
 272 }
 273
 274 const (
 275         userIdleSeconds   = 300 // time in seconds before an inactive user is marked idle
 276         idleCheckInterval = 10  // time in seconds to check for idle users
 277 )
 278
 279 // keepaliveHandler runs every idleCheckInterval seconds and increments a user's idle time by idleCheckInterval seconds.
 280 // If the updated idle time exceeds userIdleSeconds and the user was not previously idle, we notify all connected clients
 281 // that the user has gone idle.  For most clients, this turns the user grey in the user list.
 282 func (s *Server) keepaliveHandler(ctx context.Context) {
 283         ticker := time.NewTicker(idleCheckInterval * time.Second)
 284         defer ticker.Stop()
 285
 286         for {
 287                 select {
 288                 case <-ctx.Done():
 289                         return
 290                 case <-ticker.C:
 291                         for _, c := range s.ClientMgr.List() {
 292                                 c.mu.Lock()
 293                                 c.IdleTime += idleCheckInterval
 294
 295                                 // Check if the user
 296                                 if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
 297                                         c.Flags.Set(UserFlagAway, 1)
 298
 299                                         c.SendAll(
 300                                                 TranNotifyChangeUser,
 301                                                 NewField(FieldUserID, c.ID[:]),
 302                                                 NewField(FieldUserFlags, c.Flags[:]),
 303                                                 NewField(FieldUserName, c.UserName),
 304                                                 NewField(FieldUserIconID, c.Icon),
 305                                         )
 306                                 }
 307                                 c.mu.Unlock()
 308                         }
 309                 }
 310         }
 311 }
 312
 313 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 314         clientConn := &ClientConn{
 315                 Icon:       []byte{0, 0}, // TODO: make array type
 316                 Connection: conn,
 317                 Server:     s,
 318                 RemoteAddr: remoteAddr,
 319
 320                 ClientFileTransferMgr: NewClientFileTransferMgr(),
 321         }
 322
 323         s.ClientMgr.Add(clientConn)
 324
 325         return clientConn
 326 }
 327
 328 func sendBanMessage(rwc io.Writer, message string) {
 329         t := NewTransaction(
 330                 TranServerMsg,
 331                 [2]byte{0, 0},
 332                 NewField(FieldData, []byte(message)),
 333                 NewField(FieldChatOptions, []byte{0, 0}),
 334         )
 335         _, _ = io.Copy(rwc, &t)
 336         time.Sleep(1 * time.Second)
 337 }
 338
 339 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 340 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 341         defer dontPanic(s.Logger)
 342
 343         if err := performHandshake(rwc); err != nil {
 344                 return fmt.Errorf("perform handshake: %w", err)
 345         }
 346
 347         // Check if remoteAddr is present in the ban list
 348         ipAddr := strings.Split(remoteAddr, ":")[0]
 349         if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
 350                 // permaban
 351                 if banUntil == nil {
 352                         sendBanMessage(rwc, "You are permanently banned on this server")
 353                         s.Logger.Debug("Disconnecting permanently banned IP", "remoteAddr", ipAddr)
 354                         return nil
 355                 }
 356
 357                 // temporary ban
 358                 if time.Now().Before(*banUntil) {
 359                         sendBanMessage(rwc, "You are temporarily banned on this server")
 360                         s.Logger.Debug("Disconnecting temporarily banned IP", "remoteAddr", ipAddr)
 361                         return nil
 362                 }
 363         }
 364
 365         // Create a new scanner for parsing incoming bytes into transaction tokens
 366         scanner := bufio.NewScanner(rwc)
 367         scanner.Split(transactionScanner)
 368
 369         scanner.Scan()
 370
 371         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 372         // scanner re-uses the buffer for subsequent scans.
 373         buf := make([]byte, len(scanner.Bytes()))
 374         copy(buf, scanner.Bytes())
 375
 376         var clientLogin Transaction
 377         if _, err := clientLogin.Write(buf); err != nil {
 378                 return fmt.Errorf("error writing login transaction: %w", err)
 379         }
 380
 381         c := s.NewClientConn(rwc, remoteAddr)
 382         defer c.Disconnect()
 383
 384         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 385         c.Version = clientLogin.GetField(FieldVersion).Data
 386
 387         login := clientLogin.GetField(FieldUserLogin).DecodeObfuscatedString()
 388         if login == "" {
 389                 login = GuestAccount
 390         }
 391
 392         c.Logger = s.Logger.With("ip", ipAddr, "login", login)
 393
 394         // If authentication fails, send error reply and close connection
 395         if !c.Authenticate(login, encodedPassword) {
 396                 t := c.NewErrReply(&clientLogin, "Incorrect login.")[0]
 397
 398                 _, err := io.Copy(rwc, &t)
 399                 if err != nil {
 400                         return err
 401                 }
 402
 403                 c.Logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 404
 405                 return nil
 406         }
 407
 408         if clientLogin.GetField(FieldUserIconID).Data != nil {
 409                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 410         }
 411
 412         c.Account = c.Server.AccountManager.Get(login)
 413         if c.Account == nil {
 414                 return nil
 415         }
 416
 417         if clientLogin.GetField(FieldUserName).Data != nil {
 418                 if c.Authorize(AccessAnyName) {
 419                         c.UserName = clientLogin.GetField(FieldUserName).Data
 420                 } else {
 421                         c.UserName = []byte(c.Account.Name)
 422                 }
 423         }
 424
 425         if c.Authorize(AccessDisconUser) {
 426                 c.Flags.Set(UserFlagAdmin, 1)
 427         }
 428
 429         s.outbox <- c.NewReply(&clientLogin,
 430                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 431                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 432                 NewField(FieldServerName, []byte(s.Config.Name)),
 433         )
 434
 435         // Send user access privs so client UI knows how to behave
 436         c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 437
 438         // Accounts with AccessNoAgreement do not receive the server agreement on login.  The behavior is different between
 439         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 440         // TranShowAgreement but with the NoServerAgreement field set to 1.
 441         if c.Authorize(AccessNoAgreement) {
 442                 // If client version is nil, then the client uses the 1.2.3 login behavior
 443                 if c.Version != nil {
 444                         c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 445                 }
 446         } else {
 447                 _, _ = c.Server.Agreement.Seek(0, 0)
 448                 data, _ := io.ReadAll(c.Server.Agreement)
 449
 450                 c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, data))
 451         }
 452
 453         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 454         // flow and not the 1.5+ flow.
 455         if len(c.UserName) != 0 {
 456                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 457                 // part of TranAgreed
 458                 c.Logger = c.Logger.With("name", string(c.UserName))
 459                 c.Logger.Info("Login successful")
 460
 461                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 462                 // information yet, so we do it in TranAgreed instead
 463                 for _, t := range c.NotifyOthers(
 464                         NewTransaction(
 465                                 TranNotifyChangeUser, [2]byte{0, 0},
 466                                 NewField(FieldUserName, c.UserName),
 467                                 NewField(FieldUserID, c.ID[:]),
 468                                 NewField(FieldUserIconID, c.Icon),
 469                                 NewField(FieldUserFlags, c.Flags[:]),
 470                         ),
 471                 ) {
 472                         c.Server.outbox <- t
 473                 }
 474         }
 475
 476         c.Server.Stats.Increment(StatConnectionCounter, StatCurrentlyConnected)
 477         defer c.Server.Stats.Decrement(StatCurrentlyConnected)
 478
 479         if len(s.ClientMgr.List()) > c.Server.Stats.Get(StatConnectionPeak) {
 480                 c.Server.Stats.Set(StatConnectionPeak, len(s.ClientMgr.List()))
 481         }
 482
 483         // Scan for new transactions and handle them as they come in.
 484         for scanner.Scan() {
 485                 // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
 486                 tmpBuf := make([]byte, len(scanner.Bytes()))
 487                 copy(tmpBuf, scanner.Bytes())
 488
 489                 var t Transaction
 490                 if _, err := t.Write(tmpBuf); err != nil {
 491                         return err
 492                 }
 493
 494                 c.handleTransaction(t)
 495         }
 496         return nil
 497 }
 498
 499 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 500 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 501         defer dontPanic(s.Logger)
 502
 503         // The first 16 bytes contain the file transfer.
 504         var t transfer
 505         if _, err := io.CopyN(&t, rwc, 16); err != nil {
 506                 return fmt.Errorf("error reading file transfer: %w", err)
 507         }
 508
 509         fileTransfer := s.FileTransferMgr.Get(t.ReferenceNumber)
 510         if fileTransfer == nil {
 511                 return errors.New("invalid transaction ID")
 512         }
 513
 514         defer func() {
 515                 s.FileTransferMgr.Delete(t.ReferenceNumber)
 516
 517                 // Wait a few seconds before closing the connection: this is a workaround for problems
 518                 // observed with Windows clients where the client must initiate close of the TCP connection before
 519                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 520                 time.Sleep(3 * time.Second)
 521         }()
 522
 523         rLogger := s.Logger.With(
 524                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 525                 "login", fileTransfer.ClientConn.Account.Login,
 526                 "Name", string(fileTransfer.ClientConn.UserName),
 527         )
 528
 529         fullPath, err := ReadPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 530         if err != nil {
 531                 return err
 532         }
 533
 534         switch fileTransfer.Type {
 535         case BannerDownload:
 536                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.Banner)); err != nil {
 537                         return fmt.Errorf("error sending Banner: %w", err)
 538                 }
 539         case FileDownload:
 540                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 541                 defer func() {
 542                         s.Stats.Decrement(StatDownloadsInProgress)
 543                 }()
 544
 545                 err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
 546                 if err != nil {
 547                         return fmt.Errorf("file download: %w", err)
 548                 }
 549
 550         case FileUpload:
 551                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 552                 defer func() {
 553                         s.Stats.Decrement(StatUploadsInProgress)
 554                 }()
 555
 556                 err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 557                 if err != nil {
 558                         return fmt.Errorf("file upload error: %w", err)
 559                 }
 560
 561         case FolderDownload:
 562                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 563                 defer func() {
 564                         s.Stats.Decrement(StatDownloadsInProgress)
 565                 }()
 566
 567                 err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 568                 if err != nil {
 569                         return fmt.Errorf("file upload error: %w", err)
 570                 }
 571
 572         case FolderUpload:
 573                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 574                 defer func() {
 575                         s.Stats.Decrement(StatUploadsInProgress)
 576                 }()
 577
 578                 rLogger.Info(
 579                         "Folder upload started",
 580                         "dstPath", fullPath,
 581                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
 582                         "FolderItemCount", fileTransfer.FolderItemCount,
 583                 )
 584
 585                 err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 586                 if err != nil {
 587                         return fmt.Errorf("file upload error: %w", err)
 588                 }
 589         }
 590         return nil
 591 }
 592
 593 func (s *Server) SendAll(t TranType, fields ...Field) {
 594         for _, c := range s.ClientMgr.List() {
 595                 s.outbox <- NewTransaction(t, c.ID, fields...)
 596         }
 597 }
 598
 599 func (s *Server) Shutdown(msg []byte) {
 600         s.Logger.Info("Shutdown signal received")
 601         s.SendAll(TranDisconnectMsg, NewField(FieldData, msg))
 602
 603         time.Sleep(3 * time.Second)
 604
 605         os.Exit(0)
 606 }