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         "gopkg.in/yaml.v3"
  13         "io"
  14         "log"
  15         "log/slog"
  16         "net"
  17         "os"
  18         "path/filepath"
  19         "strings"
  20         "sync"
  21         "time"
  22 )
  23
  24 type contextKey string
  25
  26 var contextKeyReq = contextKey("req")
  27
  28 type requestCtx struct {
  29         remoteAddr string
  30 }
  31
  32 // Converts bytes from Mac Roman encoding to UTF-8
  33 var txtDecoder = charmap.Macintosh.NewDecoder()
  34
  35 // Converts bytes from UTF-8 to Mac Roman encoding
  36 var txtEncoder = charmap.Macintosh.NewEncoder()
  37
  38 type Server struct {
  39         NetInterface string
  40         Port         int
  41
  42         Config    Config
  43         ConfigDir string
  44         Logger    *slog.Logger
  45
  46         TrackerPassID [4]byte
  47
  48         Stats Counter
  49
  50         FS FileStore // Storage backend to use for File storage
  51
  52         outbox chan Transaction
  53
  54         // TODO
  55         Agreement []byte
  56         banner    []byte
  57         // END TODO
  58
  59         FileTransferMgr FileTransferMgr
  60         ChatMgr         ChatManager
  61         ClientMgr       ClientManager
  62         AccountManager  AccountManager
  63         ThreadedNewsMgr ThreadedNewsMgr
  64         BanList         BanMgr
  65
  66         MessageBoard io.ReadWriteSeeker
  67 }
  68
  69 // NewServer constructs a new Server from a config dir
  70 func NewServer(config Config, configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
  71         server := Server{
  72                 NetInterface:    netInterface,
  73                 Port:            netPort,
  74                 Config:          config,
  75                 ConfigDir:       configDir,
  76                 Logger:          logger,
  77                 outbox:          make(chan Transaction),
  78                 Stats:           NewStats(),
  79                 FS:              fs,
  80                 ChatMgr:         NewMemChatManager(),
  81                 ClientMgr:       NewMemClientMgr(),
  82                 FileTransferMgr: NewMemFileTransferMgr(),
  83         }
  84
  85         // generate a new random passID for tracker registration
  86         _, err := rand.Read(server.TrackerPassID[:])
  87         if err != nil {
  88                 return nil, err
  89         }
  90
  91         server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
  92         if err != nil {
  93                 return nil, err
  94         }
  95
  96         server.AccountManager, err = NewYAMLAccountManager(filepath.Join(configDir, "Users/"))
  97         if err != nil {
  98                 return nil, fmt.Errorf("error loading accounts: %w", err)
  99         }
 100
 101         // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
 102         if !filepath.IsAbs(server.Config.FileRoot) {
 103                 server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
 104         }
 105
 106         server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
 107         if err != nil {
 108                 return nil, fmt.Errorf("error opening banner: %w", err)
 109         }
 110
 111         if server.Config.EnableTrackerRegistration {
 112                 server.Logger.Info(
 113                         "Tracker registration enabled",
 114                         "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
 115                         "trackers", server.Config.Trackers,
 116                 )
 117
 118                 go server.registerWithTrackers()
 119         }
 120
 121         // Start Client Keepalive go routine
 122         go server.keepaliveHandler()
 123
 124         return &server, nil
 125 }
 126
 127 func (s *Server) CurrentStats() map[string]interface{} {
 128         return s.Stats.Values()
 129 }
 130
 131 func (s *Server) ListenAndServe(ctx context.Context) error {
 132         var wg sync.WaitGroup
 133
 134         wg.Add(1)
 135         go func() {
 136                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
 137                 if err != nil {
 138                         log.Fatal(err)
 139                 }
 140
 141                 log.Fatal(s.Serve(ctx, ln))
 142         }()
 143
 144         wg.Add(1)
 145         go func() {
 146                 ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
 147                 if err != nil {
 148                         log.Fatal(err)
 149                 }
 150
 151                 log.Fatal(s.ServeFileTransfers(ctx, ln))
 152         }()
 153
 154         wg.Wait()
 155
 156         return nil
 157 }
 158
 159 func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
 160         for {
 161                 conn, err := ln.Accept()
 162                 if err != nil {
 163                         return err
 164                 }
 165
 166                 go func() {
 167                         defer func() { _ = conn.Close() }()
 168
 169                         err = s.handleFileTransfer(
 170                                 context.WithValue(ctx, contextKeyReq, requestCtx{remoteAddr: conn.RemoteAddr().String()}),
 171                                 conn,
 172                         )
 173
 174                         if err != nil {
 175                                 s.Logger.Error("file transfer error", "reason", err)
 176                         }
 177                 }()
 178         }
 179 }
 180
 181 func (s *Server) sendTransaction(t Transaction) error {
 182         client := s.ClientMgr.Get(t.clientID)
 183
 184         if client == nil {
 185                 return nil
 186         }
 187
 188         _, err := io.Copy(client.Connection, &t)
 189         if err != nil {
 190                 return fmt.Errorf("failed to send transaction to client %v: %v", t.clientID, err)
 191         }
 192
 193         return nil
 194 }
 195
 196 func (s *Server) processOutbox() {
 197         for {
 198                 t := <-s.outbox
 199                 go func() {
 200                         if err := s.sendTransaction(t); err != nil {
 201                                 s.Logger.Error("error sending transaction", "err", err)
 202                         }
 203                 }()
 204         }
 205 }
 206
 207 func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
 208         go s.processOutbox()
 209
 210         for {
 211                 conn, err := ln.Accept()
 212                 if err != nil {
 213                         s.Logger.Error("error accepting connection", "err", err)
 214                 }
 215                 connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
 216                         remoteAddr: conn.RemoteAddr().String(),
 217                 })
 218
 219                 go func() {
 220                         s.Logger.Info("Connection established", "RemoteAddr", conn.RemoteAddr())
 221
 222                         defer conn.Close()
 223                         if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
 224                                 if err == io.EOF {
 225                                         s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
 226                                 } else {
 227                                         s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
 228                                 }
 229                         }
 230                 }()
 231         }
 232 }
 233
 234 const (
 235         agreementFile = "Agreement.txt"
 236 )
 237
 238 func (s *Server) registerWithTrackers() {
 239         for {
 240                 tr := &TrackerRegistration{
 241                         UserCount:   len(s.ClientMgr.List()),
 242                         PassID:      s.TrackerPassID,
 243                         Name:        s.Config.Name,
 244                         Description: s.Config.Description,
 245                 }
 246                 binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
 247                 for _, t := range s.Config.Trackers {
 248                         if err := register(&RealDialer{}, t, tr); err != nil {
 249                                 s.Logger.Error(fmt.Sprintf("unable to register with tracker %v", t), "error", err)
 250                         }
 251                 }
 252
 253                 time.Sleep(trackerUpdateFrequency * time.Second)
 254         }
 255 }
 256
 257 // keepaliveHandler
 258 func (s *Server) keepaliveHandler() {
 259         for {
 260                 time.Sleep(idleCheckInterval * time.Second)
 261
 262                 for _, c := range s.ClientMgr.List() {
 263                         c.mu.Lock()
 264
 265                         c.IdleTime += idleCheckInterval
 266
 267                         // Check if the user
 268                         if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
 269                                 c.Flags.Set(UserFlagAway, 1)
 270
 271                                 c.SendAll(
 272                                         TranNotifyChangeUser,
 273                                         NewField(FieldUserID, c.ID[:]),
 274                                         NewField(FieldUserFlags, c.Flags[:]),
 275                                         NewField(FieldUserName, c.UserName),
 276                                         NewField(FieldUserIconID, c.Icon),
 277                                 )
 278                         }
 279                         c.mu.Unlock()
 280                 }
 281         }
 282 }
 283
 284 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 285         clientConn := &ClientConn{
 286                 Icon:       []byte{0, 0}, // TODO: make array type
 287                 Connection: conn,
 288                 Server:     s,
 289                 RemoteAddr: remoteAddr,
 290
 291                 ClientFileTransferMgr: NewClientFileTransferMgr(),
 292         }
 293
 294         s.ClientMgr.Add(clientConn)
 295
 296         return clientConn
 297 }
 298
 299 // loadFromYAMLFile loads data from a YAML file into the provided data structure.
 300 func loadFromYAMLFile(path string, data interface{}) error {
 301         fh, err := os.Open(path)
 302         if err != nil {
 303                 return err
 304         }
 305         defer fh.Close()
 306
 307         decoder := yaml.NewDecoder(fh)
 308         return decoder.Decode(data)
 309 }
 310
 311 func sendBanMessage(rwc io.Writer, message string) {
 312         t := NewTransaction(
 313                 TranServerMsg,
 314                 [2]byte{0, 0},
 315                 NewField(FieldData, []byte(message)),
 316                 NewField(FieldChatOptions, []byte{0, 0}),
 317         )
 318         _, _ = io.Copy(rwc, &t)
 319         time.Sleep(1 * time.Second)
 320 }
 321
 322 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 323 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
 324         defer dontPanic(s.Logger)
 325
 326         // Check if remoteAddr is present in the ban list
 327         ipAddr := strings.Split(remoteAddr, ":")[0]
 328         if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
 329                 // permaban
 330                 if banUntil == nil {
 331                         sendBanMessage(rwc, "You are permanently banned on this server")
 332                         s.Logger.Debug("Disconnecting permanently banned IP", "remoteAddr", ipAddr)
 333                         return nil
 334                 }
 335
 336                 // temporary ban
 337                 if time.Now().Before(*banUntil) {
 338                         sendBanMessage(rwc, "You are temporarily banned on this server")
 339                         s.Logger.Debug("Disconnecting temporarily banned IP", "remoteAddr", ipAddr)
 340                         return nil
 341                 }
 342         }
 343
 344         if err := performHandshake(rwc); err != nil {
 345                 return fmt.Errorf("error performing handshake: %w", err)
 346         }
 347
 348         // Create a new scanner for parsing incoming bytes into transaction tokens
 349         scanner := bufio.NewScanner(rwc)
 350         scanner.Split(transactionScanner)
 351
 352         scanner.Scan()
 353
 354         // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
 355         // scanner re-uses the buffer for subsequent scans.
 356         buf := make([]byte, len(scanner.Bytes()))
 357         copy(buf, scanner.Bytes())
 358
 359         var clientLogin Transaction
 360         if _, err := clientLogin.Write(buf); err != nil {
 361                 return fmt.Errorf("error writing login transaction: %w", err)
 362         }
 363
 364         c := s.NewClientConn(rwc, remoteAddr)
 365         defer c.Disconnect()
 366
 367         encodedPassword := clientLogin.GetField(FieldUserPassword).Data
 368         c.Version = clientLogin.GetField(FieldVersion).Data
 369
 370         login := clientLogin.GetField(FieldUserLogin).DecodeObfuscatedString()
 371         if login == "" {
 372                 login = GuestAccount
 373         }
 374
 375         c.logger = s.Logger.With("ip", ipAddr, "login", login)
 376
 377         // If authentication fails, send error reply and close connection
 378         if !c.Authenticate(login, encodedPassword) {
 379                 t := c.NewErrReply(&clientLogin, "Incorrect login.")[0]
 380
 381                 _, err := io.Copy(rwc, &t)
 382                 if err != nil {
 383                         return err
 384                 }
 385
 386                 c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
 387
 388                 return nil
 389         }
 390
 391         if clientLogin.GetField(FieldUserIconID).Data != nil {
 392                 c.Icon = clientLogin.GetField(FieldUserIconID).Data
 393         }
 394
 395         c.Account = c.Server.AccountManager.Get(login)
 396         if c.Account == nil {
 397                 return nil
 398         }
 399
 400         if clientLogin.GetField(FieldUserName).Data != nil {
 401                 if c.Authorize(AccessAnyName) {
 402                         c.UserName = clientLogin.GetField(FieldUserName).Data
 403                 } else {
 404                         c.UserName = []byte(c.Account.Name)
 405                 }
 406         }
 407
 408         if c.Authorize(AccessDisconUser) {
 409                 c.Flags.Set(UserFlagAdmin, 1)
 410         }
 411
 412         s.outbox <- c.NewReply(&clientLogin,
 413                 NewField(FieldVersion, []byte{0x00, 0xbe}),
 414                 NewField(FieldCommunityBannerID, []byte{0, 0}),
 415                 NewField(FieldServerName, []byte(s.Config.Name)),
 416         )
 417
 418         // Send user access privs so client UI knows how to behave
 419         c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 420
 421         // Accounts with AccessNoAgreement do not receive the server agreement on login.  The behavior is different between
 422         // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
 423         // TranShowAgreement but with the NoServerAgreement field set to 1.
 424         if c.Authorize(AccessNoAgreement) {
 425                 // If client version is nil, then the client uses the 1.2.3 login behavior
 426                 if c.Version != nil {
 427                         c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
 428                 }
 429         } else {
 430                 c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
 431         }
 432
 433         // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
 434         // flow and not the 1.5+ flow.
 435         if len(c.UserName) != 0 {
 436                 // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
 437                 // part of TranAgreed
 438                 c.logger = c.logger.With("Name", string(c.UserName))
 439                 c.logger.Info("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
 440
 441                 // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
 442                 // information yet, so we do it in TranAgreed instead
 443                 for _, t := range c.NotifyOthers(
 444                         NewTransaction(
 445                                 TranNotifyChangeUser, [2]byte{0, 0},
 446                                 NewField(FieldUserName, c.UserName),
 447                                 NewField(FieldUserID, c.ID[:]),
 448                                 NewField(FieldUserIconID, c.Icon),
 449                                 NewField(FieldUserFlags, c.Flags[:]),
 450                         ),
 451                 ) {
 452                         c.Server.outbox <- t
 453                 }
 454         }
 455
 456         c.Server.Stats.Increment(StatConnectionCounter, StatCurrentlyConnected)
 457         defer c.Server.Stats.Decrement(StatCurrentlyConnected)
 458
 459         if len(s.ClientMgr.List()) > c.Server.Stats.Get(StatConnectionPeak) {
 460                 c.Server.Stats.Set(StatConnectionPeak, len(s.ClientMgr.List()))
 461         }
 462
 463         // Scan for new transactions and handle them as they come in.
 464         for scanner.Scan() {
 465                 // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
 466                 buf := make([]byte, len(scanner.Bytes()))
 467                 copy(buf, scanner.Bytes())
 468
 469                 var t Transaction
 470                 if _, err := t.Write(buf); err != nil {
 471                         return err
 472                 }
 473
 474                 c.handleTransaction(t)
 475         }
 476         return nil
 477 }
 478
 479 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 480 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
 481         defer dontPanic(s.Logger)
 482
 483         // The first 16 bytes contain the file transfer.
 484         var t transfer
 485         if _, err := io.CopyN(&t, rwc, 16); err != nil {
 486                 return fmt.Errorf("error reading file transfer: %w", err)
 487         }
 488
 489         fileTransfer := s.FileTransferMgr.Get(t.ReferenceNumber)
 490         if fileTransfer == nil {
 491                 return errors.New("invalid transaction ID")
 492         }
 493
 494         defer func() {
 495                 s.FileTransferMgr.Delete(t.ReferenceNumber)
 496
 497                 // Wait a few seconds before closing the connection: this is a workaround for problems
 498                 // observed with Windows clients where the client must initiate close of the TCP connection before
 499                 // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
 500                 time.Sleep(3 * time.Second)
 501         }()
 502
 503         rLogger := s.Logger.With(
 504                 "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
 505                 "login", fileTransfer.ClientConn.Account.Login,
 506                 "Name", string(fileTransfer.ClientConn.UserName),
 507         )
 508
 509         fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
 510         if err != nil {
 511                 return err
 512         }
 513
 514         switch fileTransfer.Type {
 515         case BannerDownload:
 516                 if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
 517                         return fmt.Errorf("error sending banner: %w", err)
 518                 }
 519         case FileDownload:
 520                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 521                 defer func() {
 522                         s.Stats.Decrement(StatDownloadsInProgress)
 523                 }()
 524
 525                 err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
 526                 if err != nil {
 527                         return fmt.Errorf("file download: %w", err)
 528                 }
 529
 530         case FileUpload:
 531                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 532                 defer func() {
 533                         s.Stats.Decrement(StatUploadsInProgress)
 534                 }()
 535
 536                 err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 537                 if err != nil {
 538                         return fmt.Errorf("file upload error: %w", err)
 539                 }
 540
 541         case FolderDownload:
 542                 s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
 543                 defer func() {
 544                         s.Stats.Decrement(StatDownloadsInProgress)
 545                 }()
 546
 547                 err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
 548                 if err != nil {
 549                         return fmt.Errorf("file upload error: %w", err)
 550                 }
 551
 552         case FolderUpload:
 553                 s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
 554                 defer func() {
 555                         s.Stats.Decrement(StatUploadsInProgress)
 556                 }()
 557
 558                 rLogger.Info(
 559                         "Folder upload started",
 560                         "dstPath", fullPath,
 561                         "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
 562                         "FolderItemCount", fileTransfer.FolderItemCount,
 563                 )
 564
 565                 err = UploadFolderHandler(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         return nil
 571 }