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[rbdr/mobius] / hotline / server.go
diff --git a/hotline/server.go b/hotline/server.go
index 0ee2dd7322d3dc6a0c4317a30c33a26b19dcc0ff..a521a6bfecd22adc2a28c68ca1a4b6062ca3bbed 100644 (file)
--- a/hotline/server.go
+++ b/hotline/server.go
@@ -8,19 +8,15 @@ import (
        "encoding/binary"
        "errors"
        "fmt"
        "encoding/binary"
        "errors"
        "fmt"
-       "github.com/go-playground/validator/v10"
        "golang.org/x/text/encoding/charmap"
        "golang.org/x/text/encoding/charmap"
-       "gopkg.in/yaml.v3"
+       "golang.org/x/time/rate"
        "io"
        "log"
        "log/slog"
        "net"
        "os"
        "io"
        "log"
        "log/slog"
        "net"
        "os"
-       "path"
-       "path/filepath"
        "strings"
        "sync"
        "strings"
        "sync"
-       "sync/atomic"
        "time"
 )
 
        "time"
 )
 
@@ -41,57 +37,100 @@ var txtEncoder = charmap.Macintosh.NewEncoder()
 type Server struct {
        NetInterface string
        Port         int
 type Server struct {
        NetInterface string
        Port         int
-       Accounts     map[string]*Account
-       Agreement    []byte
 
 
-       Clients       map[[2]byte]*ClientConn
-       fileTransfers map[[4]byte]*FileTransfer
+       rateLimiters map[string]*rate.Limiter
 
 
-       Config    *Config
-       ConfigDir string
-       Logger    *slog.Logger
-       banner    []byte
+       handlers map[TranType]HandlerFunc
 
 
-       PrivateChatsMu sync.Mutex
-       PrivateChats   map[[4]byte]*PrivateChat
+       Config Config
+       Logger *slog.Logger
 
 
-       nextClientID  atomic.Uint32
        TrackerPassID [4]byte
 
        TrackerPassID [4]byte
 
-       statsMu sync.Mutex
-       Stats   *Stats
+       Stats Counter
 
        FS FileStore // Storage backend to use for File storage
 
        outbox chan Transaction
 
        FS FileStore // Storage backend to use for File storage
 
        outbox chan Transaction
-       mux    sync.Mutex
 
 
-       threadedNewsMux sync.Mutex
-       ThreadedNews    *ThreadedNews
+       Agreement io.ReadSeeker
+       Banner    []byte
 
 
-       flatNewsMux sync.Mutex
-       FlatNews    []byte
+       FileTransferMgr FileTransferMgr
+       ChatMgr         ChatManager
+       ClientMgr       ClientManager
+       AccountManager  AccountManager
+       ThreadedNewsMgr ThreadedNewsMgr
+       BanList         BanMgr
 
 
-       banListMU sync.Mutex
-       banList   map[string]*time.Time
+       MessageBoard io.ReadWriteSeeker
 }
 
 }
 
-func (s *Server) CurrentStats() Stats {
-       s.statsMu.Lock()
-       defer s.statsMu.Unlock()
+type Option = func(s *Server)
 
 
-       stats := s.Stats
-       stats.CurrentlyConnected = len(s.Clients)
+func WithConfig(config Config) func(s *Server) {
+       return func(s *Server) {
+               s.Config = config
+       }
+}
+
+func WithLogger(logger *slog.Logger) func(s *Server) {
+       return func(s *Server) {
+               s.Logger = logger
+       }
+}
+
+// WithPort optionally overrides the default TCP port.
+func WithPort(port int) func(s *Server) {
+       return func(s *Server) {
+               s.Port = port
+       }
+}
+
+// WithInterface optionally sets a specific interface to listen on.
+func WithInterface(netInterface string) func(s *Server) {
+       return func(s *Server) {
+               s.NetInterface = netInterface
+       }
+}
+
+type ServerConfig struct {
+}
+
+func NewServer(options ...Option) (*Server, error) {
+       server := Server{
+               handlers:        make(map[TranType]HandlerFunc),
+               outbox:          make(chan Transaction),
+               rateLimiters:    make(map[string]*rate.Limiter),
+               FS:              &OSFileStore{},
+               ChatMgr:         NewMemChatManager(),
+               ClientMgr:       NewMemClientMgr(),
+               FileTransferMgr: NewMemFileTransferMgr(),
+               Stats:           NewStats(),
+       }
+
+       for _, opt := range options {
+               opt(&server)
+       }
+
+       // generate a new random passID for tracker registration
+       _, err := rand.Read(server.TrackerPassID[:])
+       if err != nil {
+               return nil, err
+       }
 
 
-       return *stats
+       return &server, nil
 }
 
 }
 
-type PrivateChat struct {
-       Subject    string
-       ClientConn map[[2]byte]*ClientConn
+func (s *Server) CurrentStats() map[string]interface{} {
+       return s.Stats.Values()
 }
 
 func (s *Server) ListenAndServe(ctx context.Context) error {
 }
 
 func (s *Server) ListenAndServe(ctx context.Context) error {
+       go s.registerWithTrackers(ctx)
+       go s.keepaliveHandler(ctx)
+       go s.processOutbox()
+
        var wg sync.WaitGroup
 
        wg.Add(1)
        var wg sync.WaitGroup
 
        wg.Add(1)
@@ -135,24 +174,22 @@ func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error
                        )
 
                        if err != nil {
                        )
 
                        if err != nil {
-                               s.Logger.Error("file transfer error", "reason", err)
+                               s.Logger.Error("file transfer error", "err", err)
                        }
                }()
        }
 }
 
 func (s *Server) sendTransaction(t Transaction) error {
                        }
                }()
        }
 }
 
 func (s *Server) sendTransaction(t Transaction) error {
-       s.mux.Lock()
-       client, ok := s.Clients[t.clientID]
-       s.mux.Unlock()
+       client := s.ClientMgr.Get(t.ClientID)
 
 
-       if !ok || client == nil {
+       if client == nil {
                return nil
        }
 
        _, err := io.Copy(client.Connection, &t)
        if err != nil {
                return nil
        }
 
        _, err := io.Copy(client.Connection, &t)
        if err != nil {
-               return fmt.Errorf("failed to send transaction to client %v: %v", t.clientID, err)
+               return fmt.Errorf("failed to send transaction to client %v: %v", t.ClientID, err)
        }
 
        return nil
        }
 
        return nil
@@ -169,381 +206,151 @@ func (s *Server) processOutbox() {
        }
 }
 
        }
 }
 
-func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
-       go s.processOutbox()
+// perIPRateLimit controls how frequently an IP address can connect before being throttled.
+// 0.5 = 1 connection every 2 seconds
+const perIPRateLimit = rate.Limit(0.5)
 
 
+func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
        for {
        for {
-               conn, err := ln.Accept()
-               if err != nil {
-                       s.Logger.Error("error accepting connection", "err", err)
-               }
-               connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
-                       remoteAddr: conn.RemoteAddr().String(),
-               })
-
-               go func() {
-                       s.Logger.Info("Connection established", "RemoteAddr", conn.RemoteAddr())
-
-                       defer conn.Close()
-                       if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
-                               if err == io.EOF {
-                                       s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
-                               } else {
-                                       s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
-                               }
+               select {
+               case <-ctx.Done():
+                       s.Logger.Info("Server shutting down")
+                       return ctx.Err()
+               default:
+                       conn, err := ln.Accept()
+                       if err != nil {
+                               s.Logger.Error("Error accepting connection", "err", err)
+                               continue
                        }
                        }
-               }()
-       }
-}
-
-const (
-       agreementFile = "Agreement.txt"
-)
 
 
-// NewServer constructs a new Server from a config dir
-// TODO: move config file reads out of this function
-func NewServer(configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
-       server := Server{
-               NetInterface:  netInterface,
-               Port:          netPort,
-               Accounts:      make(map[string]*Account),
-               Config:        new(Config),
-               Clients:       make(map[[2]byte]*ClientConn),
-               fileTransfers: make(map[[4]byte]*FileTransfer),
-               PrivateChats:  make(map[[4]byte]*PrivateChat),
-               ConfigDir:     configDir,
-               Logger:        logger,
-               outbox:        make(chan Transaction),
-               Stats:         &Stats{Since: time.Now()},
-               ThreadedNews:  &ThreadedNews{},
-               FS:            fs,
-               banList:       make(map[string]*time.Time),
-       }
-
-       var err error
-
-       // generate a new random passID for tracker registration
-       if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
-               return nil, err
-       }
-
-       server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
-       if err != nil {
-               return nil, err
-       }
+                       go func() {
+                               ipAddr := strings.Split(conn.RemoteAddr().(*net.TCPAddr).String(), ":")[0]
 
 
-       if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
-               return nil, err
-       }
+                               connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
+                                       remoteAddr: conn.RemoteAddr().String(),
+                               })
 
 
-       // try to load the ban list, but ignore errors as this file may not be present or may be empty
-       //_ = server.loadBanList(filepath.Join(configDir, "Banlist.yaml"))
+                               s.Logger.Info("Connection established", "ip", ipAddr)
+                               defer conn.Close()
 
 
-       _ = loadFromYAMLFile(filepath.Join(configDir, "Banlist.yaml"), &server.banList)
-
-       err = loadFromYAMLFile(filepath.Join(configDir, "ThreadedNews.yaml"), &server.ThreadedNews)
-       if err != nil {
-               return nil, fmt.Errorf("error loading threaded news: %w", err)
-       }
+                               // Check if we have an existing rate limit for the IP and create one if we do not.
+                               rl, ok := s.rateLimiters[ipAddr]
+                               if !ok {
+                                       rl = rate.NewLimiter(perIPRateLimit, 1)
+                                       s.rateLimiters[ipAddr] = rl
+                               }
 
 
-       err = server.loadConfig(filepath.Join(configDir, "config.yaml"))
-       if err != nil {
-               return nil, fmt.Errorf("error loading config: %w", err)
-       }
+                               // Check if the rate limit is exceeded and close the connection if so.
+                               if !rl.Allow() {
+                                       s.Logger.Info("Rate limit exceeded", "RemoteAddr", conn.RemoteAddr())
+                                       conn.Close()
+                                       return
+                               }
 
 
-       if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
-               return nil, err
+                               if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
+                                       if err == io.EOF {
+                                               s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
+                                       } else {
+                                               s.Logger.Error("Error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
+                                       }
+                               }
+                       }()
+               }
        }
        }
+}
 
 
-       // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
-       if !filepath.IsAbs(server.Config.FileRoot) {
-               server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
-       }
+// time in seconds between tracker re-registration
+const trackerUpdateFrequency = 300
 
 
-       server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
-       if err != nil {
-               return nil, fmt.Errorf("error opening banner: %w", err)
+// registerWithTrackers runs every trackerUpdateFrequency seconds to update the server's tracker entry on all configured
+// trackers.
+func (s *Server) registerWithTrackers(ctx context.Context) {
+       if s.Config.EnableTrackerRegistration {
+               s.Logger.Info("Tracker registration enabled", "trackers", s.Config.Trackers)
        }
 
        }
 
-       if server.Config.EnableTrackerRegistration {
-               server.Logger.Info(
-                       "Tracker registration enabled",
-                       "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
-                       "trackers", server.Config.Trackers,
-               )
-
-               go func() {
-                       for {
+       for {
+               if s.Config.EnableTrackerRegistration {
+                       for _, t := range s.Config.Trackers {
                                tr := &TrackerRegistration{
                                tr := &TrackerRegistration{
-                                       UserCount:   server.userCount(),
-                                       PassID:      server.TrackerPassID,
-                                       Name:        server.Config.Name,
-                                       Description: server.Config.Description,
+                                       UserCount:   len(s.ClientMgr.List()),
+                                       PassID:      s.TrackerPassID,
+                                       Name:        s.Config.Name,
+                                       Description: s.Config.Description,
                                }
                                }
-                               binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
-                               for _, t := range server.Config.Trackers {
-                                       if err := register(&RealDialer{}, t, tr); err != nil {
-                                               server.Logger.Error("unable to register with tracker %v", "error", err)
-                                       }
-                                       server.Logger.Debug("Sent Tracker registration", "addr", t)
+                               binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
+
+                               // Check the tracker string for a password.  This is janky but avoids a breaking change to the Config
+                               // Trackers field.
+                               splitAddr := strings.Split(":", t)
+                               if len(splitAddr) == 3 {
+                                       tr.Password = splitAddr[2]
                                }
 
                                }
 
-                               time.Sleep(trackerUpdateFrequency * time.Second)
+                               if err := register(&RealDialer{}, t, tr); err != nil {
+                                       s.Logger.Error(fmt.Sprintf("Unable to register with tracker %v", t), "error", err)
+                               }
                        }
                        }
-               }()
+               }
+               // Using time.Ticker with for/select would be more idiomatic, but it's super annoying that it doesn't tick on
+               // first pass.  Revist, maybe.
+               // https://github.com/golang/go/issues/17601
+               time.Sleep(trackerUpdateFrequency * time.Second)
        }
        }
-
-       // Start Client Keepalive go routine
-       go server.keepaliveHandler()
-
-       return &server, nil
 }
 
 }
 
-func (s *Server) userCount() int {
-       s.mux.Lock()
-       defer s.mux.Unlock()
+const (
+       userIdleSeconds   = 300 // time in seconds before an inactive user is marked idle
+       idleCheckInterval = 10  // time in seconds to check for idle users
+)
 
 
-       return len(s.Clients)
-}
+// keepaliveHandler runs every idleCheckInterval seconds and increments a user's idle time by idleCheckInterval seconds.
+// If the updated idle time exceeds userIdleSeconds and the user was not previously idle, we notify all connected clients
+// that the user has gone idle.  For most clients, this turns the user grey in the user list.
+func (s *Server) keepaliveHandler(ctx context.Context) {
+       ticker := time.NewTicker(idleCheckInterval * time.Second)
+       defer ticker.Stop()
 
 
-func (s *Server) keepaliveHandler() {
        for {
        for {
-               time.Sleep(idleCheckInterval * time.Second)
-               s.mux.Lock()
-
-               for _, c := range s.Clients {
-                       c.IdleTime += idleCheckInterval
-                       if c.IdleTime > userIdleSeconds && !c.Idle {
-                               c.Idle = true
-
-                               c.flagsMU.Lock()
-                               c.Flags.Set(UserFlagAway, 1)
-                               c.flagsMU.Unlock()
-                               c.sendAll(
-                                       TranNotifyChangeUser,
-                                       NewField(FieldUserID, c.ID[:]),
-                                       NewField(FieldUserFlags, c.Flags[:]),
-                                       NewField(FieldUserName, c.UserName),
-                                       NewField(FieldUserIconID, c.Icon),
-                               )
+               select {
+               case <-ctx.Done():
+                       return
+               case <-ticker.C:
+                       for _, c := range s.ClientMgr.List() {
+                               c.mu.Lock()
+                               c.IdleTime += idleCheckInterval
+
+                               // Check if the user
+                               if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
+                                       c.Flags.Set(UserFlagAway, 1)
+
+                                       c.SendAll(
+                                               TranNotifyChangeUser,
+                                               NewField(FieldUserID, c.ID[:]),
+                                               NewField(FieldUserFlags, c.Flags[:]),
+                                               NewField(FieldUserName, c.UserName),
+                                               NewField(FieldUserIconID, c.Icon),
+                                       )
+                               }
+                               c.mu.Unlock()
                        }
                }
                        }
                }
-               s.mux.Unlock()
        }
 }
 
        }
 }
 
-func (s *Server) writeBanList() error {
-       s.banListMU.Lock()
-       defer s.banListMU.Unlock()
-
-       out, err := yaml.Marshal(s.banList)
-       if err != nil {
-               return err
-       }
-       err = os.WriteFile(
-               filepath.Join(s.ConfigDir, "Banlist.yaml"),
-               out,
-               0666,
-       )
-       return err
-}
-
-func (s *Server) writeThreadedNews() error {
-       s.threadedNewsMux.Lock()
-       defer s.threadedNewsMux.Unlock()
-
-       out, err := yaml.Marshal(s.ThreadedNews)
-       if err != nil {
-               return err
-       }
-       err = s.FS.WriteFile(
-               filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
-               out,
-               0666,
-       )
-       return err
-}
-
 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
 func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
-       s.mux.Lock()
-       defer s.mux.Unlock()
-
        clientConn := &ClientConn{
                Icon:       []byte{0, 0}, // TODO: make array type
                Connection: conn,
                Server:     s,
                RemoteAddr: remoteAddr,
        clientConn := &ClientConn{
                Icon:       []byte{0, 0}, // TODO: make array type
                Connection: conn,
                Server:     s,
                RemoteAddr: remoteAddr,
-               transfers: map[int]map[[4]byte]*FileTransfer{
-                       FileDownload:   {},
-                       FileUpload:     {},
-                       FolderDownload: {},
-                       FolderUpload:   {},
-                       bannerDownload: {},
-               },
-       }
-
-       s.nextClientID.Add(1)
-
-       binary.BigEndian.PutUint16(clientConn.ID[:], uint16(s.nextClientID.Load()))
-       s.Clients[clientConn.ID] = clientConn
-
-       return clientConn
-}
-
-// NewUser creates a new user account entry in the server map and config file
-func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
-       s.mux.Lock()
-       defer s.mux.Unlock()
-
-       account := NewAccount(login, name, password, access)
-
-       // Create account file, returning an error if one already exists.
-       file, err := os.OpenFile(
-               filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
-               os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644,
-       )
-       if err != nil {
-               return fmt.Errorf("error creating account file: %w", err)
-       }
-       defer file.Close()
-
-       b, err := yaml.Marshal(account)
-       if err != nil {
-               return err
-       }
-
-       _, err = file.Write(b)
-       if err != nil {
-               return fmt.Errorf("error writing account file: %w", err)
-       }
-
-       s.Accounts[login] = account
-
-       return nil
-}
-
-func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
-       s.mux.Lock()
-       defer s.mux.Unlock()
-
-       // If the login has changed, rename the account file.
-       if login != newLogin {
-               err := os.Rename(
-                       filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"),
-                       filepath.Join(s.ConfigDir, "Users", path.Join("/", newLogin)+".yaml"),
-               )
-               if err != nil {
-                       return fmt.Errorf("error renaming account file: %w", err)
-               }
-               s.Accounts[newLogin] = s.Accounts[login]
-               s.Accounts[newLogin].Login = newLogin
-               delete(s.Accounts, login)
-       }
-
-       account := s.Accounts[newLogin]
-       account.Access = access
-       account.Name = name
-       account.Password = password
-
-       out, err := yaml.Marshal(&account)
-       if err != nil {
-               return err
-       }
-
-       if err := os.WriteFile(filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"), out, 0666); err != nil {
-               return fmt.Errorf("error writing account file: %w", err)
-       }
-
-       return nil
-}
-
-// DeleteUser deletes the user account
-func (s *Server) DeleteUser(login string) error {
-       s.mux.Lock()
-       defer s.mux.Unlock()
-
-       err := s.FS.Remove(filepath.Join(s.ConfigDir, "Users", path.Join("/", login)+".yaml"))
-       if err != nil {
-               return err
-       }
-
-       delete(s.Accounts, login)
-
-       return nil
-}
-
-func (s *Server) connectedUsers() []Field {
-       //s.mux.Lock()
-       //defer s.mux.Unlock()
-
-       var connectedUsers []Field
-       for _, c := range sortedClients(s.Clients) {
-               b, err := io.ReadAll(&User{
-                       ID:    c.ID,
-                       Icon:  c.Icon,
-                       Flags: c.Flags[:],
-                       Name:  string(c.UserName),
-               })
-               if err != nil {
-                       return nil
-               }
-               connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, b))
-       }
-       return connectedUsers
-}
-
-// loadFromYAMLFile loads data from a YAML file into the provided data structure.
-func loadFromYAMLFile(path string, data interface{}) error {
-       fh, err := os.Open(path)
-       if err != nil {
-               return err
-       }
-       defer fh.Close()
-
-       decoder := yaml.NewDecoder(fh)
-       return decoder.Decode(data)
-}
-
-// loadAccounts loads account data from disk
-func (s *Server) loadAccounts(userDir string) error {
-       matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
-       if err != nil {
-               return err
-       }
 
 
-       if len(matches) == 0 {
-               return fmt.Errorf("no accounts found in directory: %s", userDir)
+               ClientFileTransferMgr: NewClientFileTransferMgr(),
        }
 
        }
 
-       for _, file := range matches {
-               var account Account
-               if err = loadFromYAMLFile(file, &account); err != nil {
-                       return fmt.Errorf("error loading account %s: %w", file, err)
-               }
-
-               s.Accounts[account.Login] = &account
-       }
-       return nil
-}
+       s.ClientMgr.Add(clientConn)
 
 
-func (s *Server) loadConfig(path string) error {
-       fh, err := s.FS.Open(path)
-       if err != nil {
-               return err
-       }
-
-       decoder := yaml.NewDecoder(fh)
-       err = decoder.Decode(s.Config)
-       if err != nil {
-               return err
-       }
-
-       validate := validator.New()
-       err = validate.Struct(s.Config)
-       if err != nil {
-               return err
-       }
-       return nil
+       return clientConn
 }
 
 func sendBanMessage(rwc io.Writer, message string) {
 }
 
 func sendBanMessage(rwc io.Writer, message string) {
@@ -561,9 +368,13 @@ func sendBanMessage(rwc io.Writer, message string) {
 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
        defer dontPanic(s.Logger)
 
 func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
        defer dontPanic(s.Logger)
 
+       if err := performHandshake(rwc); err != nil {
+               return fmt.Errorf("perform handshake: %w", err)
+       }
+
        // Check if remoteAddr is present in the ban list
        ipAddr := strings.Split(remoteAddr, ":")[0]
        // Check if remoteAddr is present in the ban list
        ipAddr := strings.Split(remoteAddr, ":")[0]
-       if banUntil, ok := s.banList[ipAddr]; ok {
+       if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
                // permaban
                if banUntil == nil {
                        sendBanMessage(rwc, "You are permanently banned on this server")
                // permaban
                if banUntil == nil {
                        sendBanMessage(rwc, "You are permanently banned on this server")
@@ -579,10 +390,6 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
                }
        }
 
                }
        }
 
-       if err := performHandshake(rwc); err != nil {
-               return fmt.Errorf("error performing handshake: %w", err)
-       }
-
        // Create a new scanner for parsing incoming bytes into transaction tokens
        scanner := bufio.NewScanner(rwc)
        scanner.Split(transactionScanner)
        // Create a new scanner for parsing incoming bytes into transaction tokens
        scanner := bufio.NewScanner(rwc)
        scanner.Split(transactionScanner)
@@ -605,12 +412,12 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
        encodedPassword := clientLogin.GetField(FieldUserPassword).Data
        c.Version = clientLogin.GetField(FieldVersion).Data
 
        encodedPassword := clientLogin.GetField(FieldUserPassword).Data
        c.Version = clientLogin.GetField(FieldVersion).Data
 
-       login := string(encodeString(clientLogin.GetField(FieldUserLogin).Data))
+       login := clientLogin.GetField(FieldUserLogin).DecodeObfuscatedString()
        if login == "" {
                login = GuestAccount
        }
 
        if login == "" {
                login = GuestAccount
        }
 
-       c.logger = s.Logger.With("remoteAddr", remoteAddr, "login", login)
+       c.Logger = s.Logger.With("ip", ipAddr, "login", login)
 
        // If authentication fails, send error reply and close connection
        if !c.Authenticate(login, encodedPassword) {
 
        // If authentication fails, send error reply and close connection
        if !c.Authenticate(login, encodedPassword) {
@@ -621,7 +428,7 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
                        return err
                }
 
                        return err
                }
 
-               c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
+               c.Logger.Info("Incorrect login")
 
                return nil
        }
 
                return nil
        }
@@ -630,19 +437,20 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
                c.Icon = clientLogin.GetField(FieldUserIconID).Data
        }
 
                c.Icon = clientLogin.GetField(FieldUserIconID).Data
        }
 
-       c.Lock()
-       c.Account = c.Server.Accounts[login]
-       c.Unlock()
+       c.Account = c.Server.AccountManager.Get(login)
+       if c.Account == nil {
+               return nil
+       }
 
        if clientLogin.GetField(FieldUserName).Data != nil {
 
        if clientLogin.GetField(FieldUserName).Data != nil {
-               if c.Authorize(accessAnyName) {
+               if c.Authorize(AccessAnyName) {
                        c.UserName = clientLogin.GetField(FieldUserName).Data
                } else {
                        c.UserName = []byte(c.Account.Name)
                }
        }
 
                        c.UserName = clientLogin.GetField(FieldUserName).Data
                } else {
                        c.UserName = []byte(c.Account.Name)
                }
        }
 
-       if c.Authorize(accessDisconUser) {
+       if c.Authorize(AccessDisconUser) {
                c.Flags.Set(UserFlagAdmin, 1)
        }
 
                c.Flags.Set(UserFlagAdmin, 1)
        }
 
@@ -655,16 +463,19 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
        // Send user access privs so client UI knows how to behave
        c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 
        // Send user access privs so client UI knows how to behave
        c.Server.outbox <- NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, c.Account.Access[:]))
 
-       // Accounts with accessNoAgreement do not receive the server agreement on login.  The behavior is different between
+       // Accounts with AccessNoAgreement do not receive the server agreement on login.  The behavior is different between
        // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
        // TranShowAgreement but with the NoServerAgreement field set to 1.
        // client versions.  For 1.2.3 client, we do not send TranShowAgreement.  For other client versions, we send
        // TranShowAgreement but with the NoServerAgreement field set to 1.
-       if c.Authorize(accessNoAgreement) {
+       if c.Authorize(AccessNoAgreement) {
                // If client version is nil, then the client uses the 1.2.3 login behavior
                if c.Version != nil {
                        c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
                }
        } else {
                // If client version is nil, then the client uses the 1.2.3 login behavior
                if c.Version != nil {
                        c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
                }
        } else {
-               c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
+               _, _ = c.Server.Agreement.Seek(0, 0)
+               data, _ := io.ReadAll(c.Server.Agreement)
+
+               c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, data))
        }
 
        // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
        }
 
        // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
@@ -672,12 +483,12 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
        if len(c.UserName) != 0 {
                // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
                // part of TranAgreed
        if len(c.UserName) != 0 {
                // Add the client username to the logger.  For 1.5+ clients, we don't have this information yet as it comes as
                // part of TranAgreed
-               c.logger = c.logger.With("Name", string(c.UserName))
-               c.logger.Info("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
+               c.Logger = c.Logger.With("name", string(c.UserName))
+               c.Logger.Info("Login successful")
 
                // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
                // information yet, so we do it in TranAgreed instead
 
                // Notify other clients on the server that the new user has logged in.  For 1.5+ clients we don't have this
                // information yet, so we do it in TranAgreed instead
-               for _, t := range c.notifyOthers(
+               for _, t := range c.NotifyOthers(
                        NewTransaction(
                                TranNotifyChangeUser, [2]byte{0, 0},
                                NewField(FieldUserName, c.UserName),
                        NewTransaction(
                                TranNotifyChangeUser, [2]byte{0, 0},
                                NewField(FieldUserName, c.UserName),
@@ -690,21 +501,21 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
                }
        }
 
                }
        }
 
-       c.Server.mux.Lock()
-       c.Server.Stats.ConnectionCounter += 1
-       if len(s.Clients) > c.Server.Stats.ConnectionPeak {
-               c.Server.Stats.ConnectionPeak = len(s.Clients)
+       c.Server.Stats.Increment(StatConnectionCounter, StatCurrentlyConnected)
+       defer c.Server.Stats.Decrement(StatCurrentlyConnected)
+
+       if len(s.ClientMgr.List()) > c.Server.Stats.Get(StatConnectionPeak) {
+               c.Server.Stats.Set(StatConnectionPeak, len(s.ClientMgr.List()))
        }
        }
-       c.Server.mux.Unlock()
 
        // Scan for new transactions and handle them as they come in.
        for scanner.Scan() {
                // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
 
        // Scan for new transactions and handle them as they come in.
        for scanner.Scan() {
                // Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
-               buf := make([]byte, len(scanner.Bytes()))
-               copy(buf, scanner.Bytes())
+               tmpBuf := make([]byte, len(scanner.Bytes()))
+               copy(tmpBuf, scanner.Bytes())
 
                var t Transaction
 
                var t Transaction
-               if _, err := t.Write(buf); err != nil {
+               if _, err := t.Write(tmpBuf); err != nil {
                        return err
                }
 
                        return err
                }
 
@@ -713,25 +524,6 @@ func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser
        return nil
 }
 
        return nil
 }
 
-func (s *Server) NewPrivateChat(cc *ClientConn) [4]byte {
-       s.PrivateChatsMu.Lock()
-       defer s.PrivateChatsMu.Unlock()
-
-       var randID [4]byte
-       _, _ = rand.Read(randID[:])
-
-       s.PrivateChats[randID] = &PrivateChat{
-               ClientConn: make(map[[2]byte]*ClientConn),
-       }
-       s.PrivateChats[randID].ClientConn[cc.ID] = cc
-
-       return randID
-}
-
-const dlFldrActionSendFile = 1
-const dlFldrActionResumeFile = 2
-const dlFldrActionNextFile = 3
-
 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
        defer dontPanic(s.Logger)
 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
 func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
        defer dontPanic(s.Logger)
@@ -742,10 +534,13 @@ func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) erro
                return fmt.Errorf("error reading file transfer: %w", err)
        }
 
                return fmt.Errorf("error reading file transfer: %w", err)
        }
 
+       fileTransfer := s.FileTransferMgr.Get(t.ReferenceNumber)
+       if fileTransfer == nil {
+               return errors.New("invalid transaction ID")
+       }
+
        defer func() {
        defer func() {
-               s.mux.Lock()
-               delete(s.fileTransfers, t.ReferenceNumber)
-               s.mux.Unlock()
+               s.FileTransferMgr.Delete(t.ReferenceNumber)
 
                // Wait a few seconds before closing the connection: this is a workaround for problems
                // observed with Windows clients where the client must initiate close of the TCP connection before
 
                // Wait a few seconds before closing the connection: this is a workaround for problems
                // observed with Windows clients where the client must initiate close of the TCP connection before
@@ -753,82 +548,97 @@ func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) erro
                time.Sleep(3 * time.Second)
        }()
 
                time.Sleep(3 * time.Second)
        }()
 
-       s.mux.Lock()
-       fileTransfer, ok := s.fileTransfers[t.ReferenceNumber]
-       s.mux.Unlock()
-       if !ok {
-               return errors.New("invalid transaction ID")
-       }
-
-       defer func() {
-               fileTransfer.ClientConn.transfersMU.Lock()
-               delete(fileTransfer.ClientConn.transfers[fileTransfer.Type], t.ReferenceNumber)
-               fileTransfer.ClientConn.transfersMU.Unlock()
-       }()
-
        rLogger := s.Logger.With(
                "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
                "login", fileTransfer.ClientConn.Account.Login,
                "Name", string(fileTransfer.ClientConn.UserName),
        )
 
        rLogger := s.Logger.With(
                "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
                "login", fileTransfer.ClientConn.Account.Login,
                "Name", string(fileTransfer.ClientConn.UserName),
        )
 
-       fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
+       fullPath, err := ReadPath(fileTransfer.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
        if err != nil {
                return err
        }
 
        switch fileTransfer.Type {
        if err != nil {
                return err
        }
 
        switch fileTransfer.Type {
-       case bannerDownload:
-               if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
-                       return fmt.Errorf("error sending banner: %w", err)
+       case BannerDownload:
+               if _, err := io.Copy(rwc, bytes.NewBuffer(s.Banner)); err != nil {
+                       return fmt.Errorf("banner download: %w", err)
                }
        case FileDownload:
                }
        case FileDownload:
-               s.Stats.DownloadCounter += 1
-               s.Stats.DownloadsInProgress += 1
+               s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
                defer func() {
                defer func() {
-                       s.Stats.DownloadsInProgress -= 1
+                       s.Stats.Decrement(StatDownloadsInProgress)
                }()
 
                err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
                if err != nil {
                }()
 
                err = DownloadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, true)
                if err != nil {
-                       return fmt.Errorf("file download error: %w", err)
+                       return fmt.Errorf("file download: %w", err)
                }
 
        case FileUpload:
                }
 
        case FileUpload:
-               s.Stats.UploadCounter += 1
-               s.Stats.UploadsInProgress += 1
-               defer func() { s.Stats.UploadsInProgress -= 1 }()
+               s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
+               defer func() {
+                       s.Stats.Decrement(StatUploadsInProgress)
+               }()
 
                err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
 
                err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
-                       return fmt.Errorf("file upload error: %w", err)
+                       return fmt.Errorf("file upload: %w", err)
                }
 
        case FolderDownload:
                }
 
        case FolderDownload:
-               s.Stats.DownloadCounter += 1
-               s.Stats.DownloadsInProgress += 1
-               defer func() { s.Stats.DownloadsInProgress -= 1 }()
+               s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
+               defer func() {
+                       s.Stats.Decrement(StatDownloadsInProgress)
+               }()
 
                err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
 
                err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
-                       return fmt.Errorf("file upload error: %w", err)
+                       return fmt.Errorf("folder download: %w", err)
                }
 
        case FolderUpload:
                }
 
        case FolderUpload:
-               s.Stats.UploadCounter += 1
-               s.Stats.UploadsInProgress += 1
-               defer func() { s.Stats.UploadsInProgress -= 1 }()
+               s.Stats.Increment(StatUploadCounter, StatUploadsInProgress)
+               defer func() {
+                       s.Stats.Decrement(StatUploadsInProgress)
+               }()
+
+               var transferSizeValue uint32
+               switch len(fileTransfer.TransferSize) {
+                       case 2: // 16-bit
+                               transferSizeValue = uint32(binary.BigEndian.Uint16(fileTransfer.TransferSize))
+                       case 4: // 32-bit
+                               transferSizeValue = binary.BigEndian.Uint32(fileTransfer.TransferSize)
+                       default:
+                               rLogger.Warn("Unexpected TransferSize length: %d bytes", len(fileTransfer.TransferSize))
+               }
+
                rLogger.Info(
                        "Folder upload started",
                        "dstPath", fullPath,
                rLogger.Info(
                        "Folder upload started",
                        "dstPath", fullPath,
-                       "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
+                       "TransferSize", transferSizeValue,
                        "FolderItemCount", fileTransfer.FolderItemCount,
                )
 
                err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
                        "FolderItemCount", fileTransfer.FolderItemCount,
                )
 
                err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
                if err != nil {
-                       return fmt.Errorf("file upload error: %w", err)
+                       return fmt.Errorf("folder upload: %w", err)
                }
        }
        return nil
 }
                }
        }
        return nil
 }
+
+func (s *Server) SendAll(t TranType, fields ...Field) {
+       for _, c := range s.ClientMgr.List() {
+               s.outbox <- NewTransaction(t, c.ID, fields...)
+       }
+}
+
+func (s *Server) Shutdown(msg []byte) {
+       s.Logger.Info("Shutdown signal received")
+       s.SendAll(TranDisconnectMsg, NewField(FieldData, msg))
+
+       time.Sleep(3 * time.Second)
+
+       os.Exit(0)
+}
Friendship Quest remix of mobius, a hotline server in go #cli