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Replace zap logger with slog
[rbdr/mobius] / hotline / server.go
diff --git a/hotline/server.go b/hotline/server.go
index 3a58893fdcc1858e5338bcc7f2273955448c187e..f2a69ad735b31c4bcd0884b13ca49c99dd3bd525 100644 (file)
--- a/hotline/server.go
+++ b/hotline/server.go
@@ -1,60 +1,89 @@
 package hotline
 
 import (
 package hotline
 
 import (
+       "bufio"
+       "bytes"
        "context"
        "encoding/binary"
        "errors"
        "fmt"
        "context"
        "encoding/binary"
        "errors"
        "fmt"
-       "go.uber.org/zap"
+       "github.com/go-playground/validator/v10"
+       "golang.org/x/text/encoding/charmap"
+       "gopkg.in/yaml.v3"
        "io"
        "io"
-       "io/ioutil"
+       "io/fs"
+       "log"
+       "log/slog"
        "math/big"
        "math/rand"
        "net"
        "os"
        "path"
        "path/filepath"
        "math/big"
        "math/rand"
        "net"
        "os"
        "path"
        "path/filepath"
-       "runtime/debug"
-       "sort"
        "strings"
        "sync"
        "time"
        "strings"
        "sync"
        "time"
-
-       "gopkg.in/yaml.v2"
 )
 
 )
 
-const (
-       userIdleSeconds        = 300 // time in seconds before an inactive user is marked idle
-       idleCheckInterval      = 10  // time in seconds to check for idle users
-       trackerUpdateFrequency = 300 // time in seconds between tracker re-registration
-)
+type contextKey string
+
+var contextKeyReq = contextKey("req")
+
+type requestCtx struct {
+       remoteAddr string
+}
+
+// Converts bytes from Mac Roman encoding to UTF-8
+var txtDecoder = charmap.Macintosh.NewDecoder()
+
+// Converts bytes from UTF-8 to Mac Roman encoding
+var txtEncoder = charmap.Macintosh.NewEncoder()
 
 type Server struct {
 
 type Server struct {
+       NetInterface  string
        Port          int
        Accounts      map[string]*Account
        Agreement     []byte
        Clients       map[uint16]*ClientConn
        Port          int
        Accounts      map[string]*Account
        Agreement     []byte
        Clients       map[uint16]*ClientConn
-       FlatNews      []byte
-       ThreadedNews  *ThreadedNews
-       FileTransfers map[uint32]*FileTransfer
-       Config        *Config
-       ConfigDir     string
-       Logger        *zap.SugaredLogger
-       PrivateChats  map[uint32]*PrivateChat
+       fileTransfers map[[4]byte]*FileTransfer
+
+       Config    *Config
+       ConfigDir string
+       Logger    *slog.Logger
+       banner    []byte
+
+       PrivateChatsMu sync.Mutex
+       PrivateChats   map[uint32]*PrivateChat
+
        NextGuestID   *uint16
        NextGuestID   *uint16
-       TrackerPassID []byte
-       Stats         *Stats
+       TrackerPassID [4]byte
 
 
-       APIListener  net.Listener
-       FileListener net.Listener
+       StatsMu sync.Mutex
+       Stats   *Stats
 
 
-       // newsReader io.Reader
-       // newsWriter io.WriteCloser
+       FS FileStore // Storage backend to use for File storage
 
        outbox chan Transaction
 
        outbox chan Transaction
+       mux    sync.Mutex
+
+       threadedNewsMux sync.Mutex
+       ThreadedNews    *ThreadedNews
 
 
-       mux         sync.Mutex
        flatNewsMux sync.Mutex
        flatNewsMux sync.Mutex
+       FlatNews    []byte
+
+       banListMU sync.Mutex
+       banList   map[string]*time.Time
+}
+
+func (s *Server) CurrentStats() Stats {
+       s.StatsMu.Lock()
+       defer s.StatsMu.Unlock()
+
+       stats := s.Stats
+       stats.CurrentlyConnected = len(s.Clients)
+
+       return *stats
 }
 
 type PrivateChat struct {
 }
 
 type PrivateChat struct {
@@ -63,27 +92,40 @@ type PrivateChat struct {
 }
 
 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
 }
 
 func (s *Server) ListenAndServe(ctx context.Context, cancelRoot context.CancelFunc) error {
-       s.Logger.Infow("Hotline server started", "version", VERSION)
+       s.Logger.Info("Hotline server started",
+               "version", VERSION,
+               "API port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port),
+               "Transfer port", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1),
+       )
+
        var wg sync.WaitGroup
 
        wg.Add(1)
        var wg sync.WaitGroup
 
        wg.Add(1)
-       go func() { s.Logger.Fatal(s.Serve(ctx, cancelRoot, s.APIListener)) }()
+       go func() {
+               ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port))
+               if err != nil {
+                       log.Fatal(err)
+               }
+
+               log.Fatal(s.Serve(ctx, ln))
+       }()
 
        wg.Add(1)
 
        wg.Add(1)
-       go func() { s.Logger.Fatal(s.ServeFileTransfers(s.FileListener)) }()
+       go func() {
+               ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", s.NetInterface, s.Port+1))
+               if err != nil {
+                       log.Fatal(err)
+               }
+
+               log.Fatal(s.ServeFileTransfers(ctx, ln))
+       }()
 
        wg.Wait()
 
        return nil
 }
 
 
        wg.Wait()
 
        return nil
 }
 
-func (s *Server) APIPort() int {
-       return s.APIListener.Addr().(*net.TCPAddr).Port
-}
-
-func (s *Server) ServeFileTransfers(ln net.Listener) error {
-       s.Logger.Infow("Hotline file transfer server started", "Addr", fmt.Sprintf(":%v", s.Port+1))
-
+func (s *Server) ServeFileTransfers(ctx context.Context, ln net.Listener) error {
        for {
                conn, err := ln.Accept()
                if err != nil {
        for {
                conn, err := ln.Accept()
                if err != nil {
@@ -91,15 +133,23 @@ func (s *Server) ServeFileTransfers(ln net.Listener) error {
                }
 
                go func() {
                }
 
                go func() {
-                       if err := s.TransferFile(conn); err != nil {
-                               s.Logger.Errorw("file transfer error", "reason", err)
+                       defer func() { _ = conn.Close() }()
+
+                       err = s.handleFileTransfer(
+                               context.WithValue(ctx, contextKeyReq, requestCtx{
+                                       remoteAddr: conn.RemoteAddr().String(),
+                               }),
+                               conn,
+                       )
+
+                       if err != nil {
+                               s.Logger.Error("file transfer error", "reason", err)
                        }
                }()
        }
 }
 
 func (s *Server) sendTransaction(t Transaction) error {
                        }
                }()
        }
 }
 
 func (s *Server) sendTransaction(t Transaction) error {
-       requestNum := binary.BigEndian.Uint16(t.Type)
        clientID, err := byteToInt(*t.clientID)
        if err != nil {
                return err
        clientID, err := byteToInt(*t.clientID)
        if err != nil {
                return err
@@ -111,55 +161,52 @@ func (s *Server) sendTransaction(t Transaction) error {
        if client == nil {
                return fmt.Errorf("invalid client id %v", *t.clientID)
        }
        if client == nil {
                return fmt.Errorf("invalid client id %v", *t.clientID)
        }
-       userName := string(client.UserName)
-       login := client.Account.Login
-
-       handler := TransactionHandlers[requestNum]
 
        b, err := t.MarshalBinary()
        if err != nil {
                return err
        }
 
        b, err := t.MarshalBinary()
        if err != nil {
                return err
        }
-       var n int
-       if n, err = client.Connection.Write(b); err != nil {
+
+       _, err = client.Connection.Write(b)
+       if err != nil {
                return err
        }
                return err
        }
-       s.Logger.Debugw("Sent Transaction",
-               "name", userName,
-               "login", login,
-               "IsReply", t.IsReply,
-               "type", handler.Name,
-               "sentBytes", n,
-               "remoteAddr", client.Connection.RemoteAddr(),
-       )
+
        return nil
 }
 
        return nil
 }
 
-func (s *Server) Serve(ctx context.Context, cancelRoot context.CancelFunc, ln net.Listener) error {
-       s.Logger.Infow("Hotline server started", "Addr", fmt.Sprintf(":%v", s.Port))
+func (s *Server) processOutbox() {
+       for {
+               t := <-s.outbox
+               go func() {
+                       if err := s.sendTransaction(t); err != nil {
+                               s.Logger.Error("error sending transaction", "err", err)
+                       }
+               }()
+       }
+}
+
+func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
+       go s.processOutbox()
 
        for {
                conn, err := ln.Accept()
                if err != nil {
 
        for {
                conn, err := ln.Accept()
                if err != nil {
-                       s.Logger.Errorw("error accepting connection", "err", err)
+                       s.Logger.Error("error accepting connection", "err", err)
                }
                }
+               connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
+                       remoteAddr: conn.RemoteAddr().String(),
+               })
 
                go func() {
 
                go func() {
-                       for {
-                               t := <-s.outbox
-                               go func() {
-                                       if err := s.sendTransaction(t); err != nil {
-                                               s.Logger.Errorw("error sending transaction", "err", err)
-                                       }
-                               }()
-                       }
-               }()
-               go func() {
-                       if err := s.handleNewConnection(conn); err != nil {
+                       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 {
                                if err == io.EOF {
-                                       s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
+                                       s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
                                } else {
                                } else {
-                                       s.Logger.Errorw("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
+                                       s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
                                }
                        }
                }()
                                }
                        }
                }()
@@ -171,85 +218,89 @@ const (
 )
 
 // NewServer constructs a new Server from a config dir
 )
 
 // NewServer constructs a new Server from a config dir
-func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredLogger) (*Server, error) {
+func NewServer(configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
        server := Server{
        server := Server{
+               NetInterface:  netInterface,
                Port:          netPort,
                Accounts:      make(map[string]*Account),
                Config:        new(Config),
                Clients:       make(map[uint16]*ClientConn),
                Port:          netPort,
                Accounts:      make(map[string]*Account),
                Config:        new(Config),
                Clients:       make(map[uint16]*ClientConn),
-               FileTransfers: make(map[uint32]*FileTransfer),
+               fileTransfers: make(map[[4]byte]*FileTransfer),
                PrivateChats:  make(map[uint32]*PrivateChat),
                ConfigDir:     configDir,
                Logger:        logger,
                NextGuestID:   new(uint16),
                outbox:        make(chan Transaction),
                PrivateChats:  make(map[uint32]*PrivateChat),
                ConfigDir:     configDir,
                Logger:        logger,
                NextGuestID:   new(uint16),
                outbox:        make(chan Transaction),
-               Stats:         &Stats{StartTime: time.Now()},
+               Stats:         &Stats{Since: time.Now()},
                ThreadedNews:  &ThreadedNews{},
                ThreadedNews:  &ThreadedNews{},
-               TrackerPassID: make([]byte, 4),
+               FS:            fs,
+               banList:       make(map[string]*time.Time),
        }
 
        }
 
-       ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
-       if err != nil {
-               return nil, err
-       }
-       server.APIListener = ln
+       var err error
 
 
-       if netPort != 0 {
-               netPort += 1
+       // generate a new random passID for tracker registration
+       if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
+               return nil, err
        }
 
        }
 
-       ln2, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
-       server.FileListener = ln2
+       server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
        if err != nil {
                return nil, err
        }
 
        if err != nil {
                return nil, err
        }
 
-       // generate a new random passID for tracker registration
-       if _, err := rand.Read(server.TrackerPassID); err != nil {
+       if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {
                return nil, err
        }
 
                return nil, err
        }
 
-       server.Logger.Debugw("Loading Agreement", "path", configDir+agreementFile)
-       if server.Agreement, err = os.ReadFile(configDir + agreementFile); err != nil {
-               return nil, err
-       }
+       // 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"))
 
 
-       if server.FlatNews, err = os.ReadFile(configDir + "MessageBoard.txt"); err != nil {
+       if err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {
                return nil, err
        }
 
                return nil, err
        }
 
-       if err := server.loadThreadedNews(configDir + "ThreadedNews.yaml"); err != nil {
+       if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {
                return nil, err
        }
 
                return nil, err
        }
 
-       if err := server.loadConfig(configDir + "config.yaml"); err != nil {
+       if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {
                return nil, err
        }
 
                return nil, err
        }
 
-       if err := server.loadAccounts(configDir + "Users/"); err != nil {
-               return nil, 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)
        }
 
        }
 
-       server.Config.FileRoot = configDir + "Files/"
+       server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
+       if err != nil {
+               return nil, fmt.Errorf("error opening banner: %w", err)
+       }
 
        *server.NextGuestID = 1
 
        if server.Config.EnableTrackerRegistration {
 
        *server.NextGuestID = 1
 
        if server.Config.EnableTrackerRegistration {
+               server.Logger.Info(
+                       "Tracker registration enabled",
+                       "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
+                       "trackers", server.Config.Trackers,
+               )
+
                go func() {
                        for {
                go func() {
                        for {
-                               tr := TrackerRegistration{
-                                       Port:        []byte{0x15, 0x7c},
+                               tr := &TrackerRegistration{
                                        UserCount:   server.userCount(),
                                        PassID:      server.TrackerPassID,
                                        Name:        server.Config.Name,
                                        Description: server.Config.Description,
                                }
                                        UserCount:   server.userCount(),
                                        PassID:      server.TrackerPassID,
                                        Name:        server.Config.Name,
                                        Description: server.Config.Description,
                                }
+                               binary.BigEndian.PutUint16(tr.Port[:], uint16(server.Port))
                                for _, t := range server.Config.Trackers {
                                for _, t := range server.Config.Trackers {
-                                       server.Logger.Infof("Registering with tracker %v", t)
-
                                        if err := register(t, tr); err != nil {
                                        if err := register(t, tr); err != nil {
-                                               server.Logger.Errorw("unable to register with tracker %v", "error", err)
+                                               server.Logger.Error("unable to register with tracker %v", "error", err)
                                        }
                                        }
+                                       server.Logger.Debug("Sent Tracker registration", "addr", t)
                                }
 
                                time.Sleep(trackerUpdateFrequency * time.Second)
                                }
 
                                time.Sleep(trackerUpdateFrequency * time.Second)
@@ -280,16 +331,16 @@ func (s *Server) keepaliveHandler() {
                        if c.IdleTime > userIdleSeconds && !c.Idle {
                                c.Idle = true
 
                        if c.IdleTime > userIdleSeconds && !c.Idle {
                                c.Idle = true
 
-                               flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
-                               flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
-                               binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
+                               flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
+                               flagBitmap.SetBit(flagBitmap, UserFlagAway, 1)
+                               binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 
                                c.sendAll(
 
                                c.sendAll(
-                                       tranNotifyChangeUser,
-                                       NewField(fieldUserID, *c.ID),
-                                       NewField(fieldUserFlags, *c.Flags),
-                                       NewField(fieldUserName, c.UserName),
-                                       NewField(fieldUserIconID, *c.Icon),
+                                       TranNotifyChangeUser,
+                                       NewField(FieldUserID, *c.ID),
+                                       NewField(FieldUserFlags, c.Flags),
+                                       NewField(FieldUserName, c.UserName),
+                                       NewField(FieldUserIconID, c.Icon),
                                )
                        }
                }
                                )
                        }
                }
@@ -297,38 +348,61 @@ func (s *Server) keepaliveHandler() {
        }
 }
 
        }
 }
 
+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 {
 func (s *Server) writeThreadedNews() error {
-       s.mux.Lock()
-       defer s.mux.Unlock()
+       s.threadedNewsMux.Lock()
+       defer s.threadedNewsMux.Unlock()
 
        out, err := yaml.Marshal(s.ThreadedNews)
        if err != nil {
                return err
        }
 
        out, err := yaml.Marshal(s.ThreadedNews)
        if err != nil {
                return err
        }
-       err = ioutil.WriteFile(
-               s.ConfigDir+"ThreadedNews.yaml",
+       err = s.FS.WriteFile(
+               filepath.Join(s.ConfigDir, "ThreadedNews.yaml"),
                out,
                0666,
        )
        return err
 }
 
                out,
                0666,
        )
        return err
 }
 
-func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
+func (s *Server) NewClientConn(conn io.ReadWriteCloser, remoteAddr string) *ClientConn {
        s.mux.Lock()
        defer s.mux.Unlock()
 
        clientConn := &ClientConn{
                ID:         &[]byte{0, 0},
        s.mux.Lock()
        defer s.mux.Unlock()
 
        clientConn := &ClientConn{
                ID:         &[]byte{0, 0},
-               Icon:       &[]byte{0, 0},
-               Flags:      &[]byte{0, 0},
+               Icon:       []byte{0, 0},
+               Flags:      []byte{0, 0},
                UserName:   []byte{},
                Connection: conn,
                Server:     s,
                UserName:   []byte{},
                Connection: conn,
                Server:     s,
-               Version:    &[]byte{},
+               Version:    []byte{},
                AutoReply:  []byte{},
                AutoReply:  []byte{},
-               Transfers:  make(map[int][]*FileTransfer),
-               Agreed:     false,
+               RemoteAddr: remoteAddr,
+               transfers: map[int]map[[4]byte]*FileTransfer{
+                       FileDownload:   {},
+                       FileUpload:     {},
+                       FolderDownload: {},
+                       FolderUpload:   {},
+                       bannerDownload: {},
+               },
        }
        }
+
        *s.NextGuestID++
        ID := *s.NextGuestID
 
        *s.NextGuestID++
        ID := *s.NextGuestID
 
@@ -339,7 +413,7 @@ func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
 }
 
 // NewUser creates a new user account entry in the server map and config file
 }
 
 // NewUser creates a new user account entry in the server map and config file
-func (s *Server) NewUser(login, name, password string, access []byte) error {
+func (s *Server) NewUser(login, name, password string, access accessBitmap) error {
        s.mux.Lock()
        defer s.mux.Unlock()
 
        s.mux.Lock()
        defer s.mux.Unlock()
 
@@ -347,15 +421,64 @@ func (s *Server) NewUser(login, name, password string, access []byte) error {
                Login:    login,
                Name:     name,
                Password: hashAndSalt([]byte(password)),
                Login:    login,
                Name:     name,
                Password: hashAndSalt([]byte(password)),
-               Access:   &access,
+               Access:   access,
        }
        out, err := yaml.Marshal(&account)
        if err != nil {
                return err
        }
        }
        out, err := yaml.Marshal(&account)
        if err != nil {
                return err
        }
+
+       // 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 err
+       }
+       defer file.Close()
+
+       _, err = file.Write(out)
+       if err != nil {
+               return fmt.Errorf("error writing account file: %w", err)
+       }
+
        s.Accounts[login] = &account
 
        s.Accounts[login] = &account
 
-       return ioutil.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
+       return nil
+}
+
+func (s *Server) UpdateUser(login, newLogin, name, password string, access accessBitmap) error {
+       s.mux.Lock()
+       defer s.mux.Unlock()
+
+       // update renames the user login
+       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("unable to rename account: %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 err
+       }
+
+       return nil
 }
 
 // DeleteUser deletes the user account
 }
 
 // DeleteUser deletes the user account
@@ -363,9 +486,14 @@ func (s *Server) DeleteUser(login string) error {
        s.mux.Lock()
        defer s.mux.Unlock()
 
        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)
 
        delete(s.Accounts, login)
 
-       return os.Remove(s.ConfigDir + "Users/" + login + ".yaml")
+       return nil
 }
 
 func (s *Server) connectedUsers() []Field {
 }
 
 func (s *Server) connectedUsers() []Field {
@@ -374,20 +502,30 @@ func (s *Server) connectedUsers() []Field {
 
        var connectedUsers []Field
        for _, c := range sortedClients(s.Clients) {
 
        var connectedUsers []Field
        for _, c := range sortedClients(s.Clients) {
-               if !c.Agreed {
-                       continue
-               }
-               user := User{
+               b, err := io.ReadAll(&User{
                        ID:    *c.ID,
                        ID:    *c.ID,
-                       Icon:  *c.Icon,
-                       Flags: *c.Flags,
+                       Icon:  c.Icon,
+                       Flags: c.Flags,
                        Name:  string(c.UserName),
                        Name:  string(c.UserName),
+               })
+               if err != nil {
+                       return nil
                }
                }
-               connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
+               connectedUsers = append(connectedUsers, NewField(FieldUsernameWithInfo, b))
        }
        return connectedUsers
 }
 
        }
        return connectedUsers
 }
 
+func (s *Server) loadBanList(path string) error {
+       fh, err := os.Open(path)
+       if err != nil {
+               return err
+       }
+       decoder := yaml.NewDecoder(fh)
+
+       return decoder.Decode(s.banList)
+}
+
 // loadThreadedNews loads the threaded news data from disk
 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
        fh, err := os.Open(threadedNewsPath)
 // loadThreadedNews loads the threaded news data from disk
 func (s *Server) loadThreadedNews(threadedNewsPath string) error {
        fh, err := os.Open(threadedNewsPath)
@@ -395,14 +533,13 @@ func (s *Server) loadThreadedNews(threadedNewsPath string) error {
                return err
        }
        decoder := yaml.NewDecoder(fh)
                return err
        }
        decoder := yaml.NewDecoder(fh)
-       decoder.SetStrict(true)
 
        return decoder.Decode(s.ThreadedNews)
 }
 
 // loadAccounts loads account data from disk
 func (s *Server) loadAccounts(userDir string) error {
 
        return decoder.Decode(s.ThreadedNews)
 }
 
 // loadAccounts loads account data from disk
 func (s *Server) loadAccounts(userDir string) error {
-       matches, err := filepath.Glob(path.Join(userDir, "*.yaml"))
+       matches, err := filepath.Glob(filepath.Join(userDir, "*.yaml"))
        if err != nil {
                return err
        }
        if err != nil {
                return err
        }
@@ -412,16 +549,15 @@ func (s *Server) loadAccounts(userDir string) error {
        }
 
        for _, file := range matches {
        }
 
        for _, file := range matches {
-               fh, err := FS.Open(file)
+               fh, err := s.FS.Open(file)
                if err != nil {
                        return err
                }
 
                account := Account{}
                decoder := yaml.NewDecoder(fh)
                if err != nil {
                        return err
                }
 
                account := Account{}
                decoder := yaml.NewDecoder(fh)
-               decoder.SetStrict(true)
-               if err := decoder.Decode(&account); err != nil {
-                       return err
+               if err = decoder.Decode(&account); err != nil {
+                       return fmt.Errorf("error loading account %s: %w", file, err)
                }
 
                s.Accounts[account.Login] = &account
                }
 
                s.Accounts[account.Login] = &account
@@ -430,61 +566,103 @@ func (s *Server) loadAccounts(userDir string) error {
 }
 
 func (s *Server) loadConfig(path string) error {
 }
 
 func (s *Server) loadConfig(path string) error {
-       fh, err := FS.Open(path)
+       fh, err := s.FS.Open(path)
        if err != nil {
                return err
        }
 
        decoder := yaml.NewDecoder(fh)
        if err != nil {
                return err
        }
 
        decoder := yaml.NewDecoder(fh)
-       decoder.SetStrict(true)
        err = decoder.Decode(s.Config)
        if err != nil {
                return err
        }
        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 nil
 }
 
-const (
-       minTransactionLen = 22 // minimum length of any transaction
-)
-
 // handleNewConnection takes a new net.Conn and performs the initial login sequence
 // handleNewConnection takes a new net.Conn and performs the initial login sequence
-func (s *Server) handleNewConnection(conn net.Conn) error {
-       handshakeBuf := make([]byte, 12) // handshakes are always 12 bytes in length
-       if _, err := conn.Read(handshakeBuf); err != nil {
-               return err
-       }
-       if err := Handshake(conn, handshakeBuf[:12]); err != nil {
-               return err
-       }
+func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
+       defer dontPanic(s.Logger)
 
 
-       buf := make([]byte, 1024)
-       readLen, err := conn.Read(buf)
-       if readLen < minTransactionLen {
+       if err := Handshake(rwc); err != nil {
                return err
        }
                return err
        }
-       if err != nil {
+
+       // Create a new scanner for parsing incoming bytes into transaction tokens
+       scanner := bufio.NewScanner(rwc)
+       scanner.Split(transactionScanner)
+
+       scanner.Scan()
+
+       // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
+       // scanner re-uses the buffer for subsequent scans.
+       buf := make([]byte, len(scanner.Bytes()))
+       copy(buf, scanner.Bytes())
+
+       var clientLogin Transaction
+       if _, err := clientLogin.Write(buf); err != nil {
                return err
        }
 
                return err
        }
 
-       clientLogin, _, err := ReadTransaction(buf[:readLen])
-       if err != nil {
-               return err
+       // check if remoteAddr is present in the ban list
+       if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
+               // permaban
+               if banUntil == nil {
+                       t := NewTransaction(
+                               TranServerMsg,
+                               &[]byte{0, 0},
+                               NewField(FieldData, []byte("You are permanently banned on this server")),
+                               NewField(FieldChatOptions, []byte{0, 0}),
+                       )
+
+                       b, err := t.MarshalBinary()
+                       if err != nil {
+                               return err
+                       }
+
+                       _, err = rwc.Write(b)
+                       if err != nil {
+                               return err
+                       }
+
+                       time.Sleep(1 * time.Second)
+                       return nil
+               }
+
+               // temporary ban
+               if time.Now().Before(*banUntil) {
+                       t := NewTransaction(
+                               TranServerMsg,
+                               &[]byte{0, 0},
+                               NewField(FieldData, []byte("You are temporarily banned on this server")),
+                               NewField(FieldChatOptions, []byte{0, 0}),
+                       )
+                       b, err := t.MarshalBinary()
+                       if err != nil {
+                               return err
+                       }
+
+                       _, err = rwc.Write(b)
+                       if err != nil {
+                               return err
+                       }
+
+                       time.Sleep(1 * time.Second)
+                       return nil
+               }
        }
 
        }
 
-       c := s.NewClientConn(conn)
+       c := s.NewClientConn(rwc, remoteAddr)
        defer c.Disconnect()
        defer c.Disconnect()
-       defer func() {
-               if r := recover(); r != nil {
-                       fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
-                       c.Server.Logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
-                       c.Disconnect()
-               }
-       }()
 
 
-       encodedLogin := clientLogin.GetField(fieldUserLogin).Data
-       encodedPassword := clientLogin.GetField(fieldUserPassword).Data
-       *c.Version = clientLogin.GetField(fieldVersion).Data
+       encodedLogin := clientLogin.GetField(FieldUserLogin).Data
+       encodedPassword := clientLogin.GetField(FieldUserPassword).Data
+       c.Version = clientLogin.GetField(FieldVersion).Data
 
        var login string
        for _, char := range encodedLogin {
 
        var login string
        for _, char := range encodedLogin {
@@ -494,107 +672,120 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
                login = GuestAccount
        }
 
                login = GuestAccount
        }
 
+       c.logger = s.Logger.With("remoteAddr", remoteAddr, "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) {
-               t := c.NewErrReply(clientLogin, "Incorrect login.")
+               t := c.NewErrReply(&clientLogin, "Incorrect login.")
                b, err := t.MarshalBinary()
                if err != nil {
                        return err
                }
                b, err := t.MarshalBinary()
                if err != nil {
                        return err
                }
-               if _, err := conn.Write(b); err != nil {
+               if _, err := rwc.Write(b); err != nil {
                        return err
                }
                        return err
                }
-               return fmt.Errorf("incorrect login")
-       }
 
 
-       if clientLogin.GetField(fieldUserName).Data != nil {
-               c.UserName = clientLogin.GetField(fieldUserName).Data
+               c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
+
+               return nil
        }
 
        }
 
-       if clientLogin.GetField(fieldUserIconID).Data != nil {
-               *c.Icon = clientLogin.GetField(fieldUserIconID).Data
+       if clientLogin.GetField(FieldUserIconID).Data != nil {
+               c.Icon = clientLogin.GetField(FieldUserIconID).Data
        }
 
        c.Account = c.Server.Accounts[login]
 
        }
 
        c.Account = c.Server.Accounts[login]
 
-       if c.Authorize(accessDisconUser) {
-               *c.Flags = []byte{0, 2}
+       if clientLogin.GetField(FieldUserName).Data != nil {
+               if c.Authorize(accessAnyName) {
+                       c.UserName = clientLogin.GetField(FieldUserName).Data
+               } else {
+                       c.UserName = []byte(c.Account.Name)
+               }
        }
 
        }
 
-       s.Logger.Infow("Client connection received", "login", login, "version", *c.Version, "RemoteAddr", conn.RemoteAddr().String())
+       if c.Authorize(accessDisconUser) {
+               c.Flags = []byte{0, 2}
+       }
 
 
-       s.outbox <- c.NewReply(clientLogin,
-               NewField(fieldVersion, []byte{0x00, 0xbe}),
-               NewField(fieldCommunityBannerID, []byte{0x00, 0x01}),
-               NewField(fieldServerName, []byte(s.Config.Name)),
+       s.outbox <- c.NewReply(&clientLogin,
+               NewField(FieldVersion, []byte{0x00, 0xbe}),
+               NewField(FieldCommunityBannerID, []byte{0, 0}),
+               NewField(FieldServerName, []byte(s.Config.Name)),
        )
 
        // Send user access privs so client UI knows how to behave
        )
 
        // Send user access privs so client UI knows how to behave
-       c.Server.outbox <- *NewTransaction(tranUserAccess, c.ID, NewField(fieldUserAccess, *c.Account.Access))
-
-       // Show agreement to client
-       c.Server.outbox <- *NewTransaction(tranShowAgreement, c.ID, NewField(fieldData, s.Agreement))
+       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
+       // 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 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))
+       }
 
 
-       // assume simplified hotline v1.2.3 login flow that does not require agreement
-       if *c.Version == nil {
-               c.Agreed = true
-               if _, err := c.notifyNewUserHasJoined(); err != nil {
-                       return err
+       // If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
+       // flow and not the 1.5+ flow.
+       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)")
+
+               // 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(
+                       *NewTransaction(
+                               TranNotifyChangeUser, nil,
+                               NewField(FieldUserName, c.UserName),
+                               NewField(FieldUserID, *c.ID),
+                               NewField(FieldUserIconID, c.Icon),
+                               NewField(FieldUserFlags, c.Flags),
+                       ),
+               ) {
+                       c.Server.outbox <- t
                }
        }
 
                }
        }
 
-       c.Server.Stats.LoginCount += 1
+       c.Server.Stats.ConnectionCounter += 1
+       if len(s.Clients) > c.Server.Stats.ConnectionPeak {
+               c.Server.Stats.ConnectionPeak = len(s.Clients)
+       }
 
 
-       const readBuffSize = 1024000 // 1KB - TODO: what should this be?
-       tranBuff := make([]byte, 0)
-       tReadlen := 0
-       // Infinite loop where take action on incoming client requests until the connection is closed
-       for {
-               buf = make([]byte, readBuffSize)
-               tranBuff = tranBuff[tReadlen:]
+       // Scan for new transactions and handle them as they come in.
+       for scanner.Scan() {
+               // Make a new []byte slice and copy the scanner bytes to it.  This is critical to avoid a data race as the
+               // scanner re-uses the buffer for subsequent scans.
+               buf := make([]byte, len(scanner.Bytes()))
+               copy(buf, scanner.Bytes())
 
 
-               readLen, err := c.Connection.Read(buf)
-               if err != nil {
+               var t Transaction
+               if _, err := t.Write(buf); err != nil {
                        return err
                }
                        return err
                }
-               tranBuff = append(tranBuff, buf[:readLen]...)
-
-               // We may have read multiple requests worth of bytes from Connection.Read.  readTransactions splits them
-               // into a slice of transactions
-               var transactions []Transaction
-               if transactions, tReadlen, err = readTransactions(tranBuff); err != nil {
-                       c.Server.Logger.Errorw("Error handling transaction", "err", err)
-               }
 
 
-               // iterate over all of the transactions that were parsed from the byte slice and handle them
-               for _, t := range transactions {
-                       if err := c.handleTransaction(&t); err != nil {
-                               c.Server.Logger.Errorw("Error handling transaction", "err", err)
-                       }
+               if err := c.handleTransaction(t); err != nil {
+                       c.logger.Error("Error handling transaction", "err", err)
                }
        }
                }
        }
-}
-
-// NewTransactionRef generates a random ID for the file transfer.  The Hotline client includes this ID
-// in the file transfer request payload, and the file transfer server will use it to map the request
-// to a transfer
-func (s *Server) NewTransactionRef() []byte {
-       transactionRef := make([]byte, 4)
-       rand.Read(transactionRef)
-
-       return transactionRef
+       return nil
 }
 
 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
 }
 
 func (s *Server) NewPrivateChat(cc *ClientConn) []byte {
-       s.mux.Lock()
-       defer s.mux.Unlock()
+       s.PrivateChatsMu.Lock()
+       defer s.PrivateChatsMu.Unlock()
 
        randID := make([]byte, 4)
        rand.Read(randID)
 
        randID := make([]byte, 4)
        rand.Read(randID)
-       data := binary.BigEndian.Uint32(randID[:])
+       data := binary.BigEndian.Uint32(randID)
 
        s.PrivateChats[data] = &PrivateChat{
 
        s.PrivateChats[data] = &PrivateChat{
-               Subject:    "",
                ClientConn: make(map[uint16]*ClientConn),
        }
        s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
                ClientConn: make(map[uint16]*ClientConn),
        }
        s.PrivateChats[data].ClientConn[cc.uint16ID()] = cc
@@ -606,392 +797,516 @@ const dlFldrActionSendFile = 1
 const dlFldrActionResumeFile = 2
 const dlFldrActionNextFile = 3
 
 const dlFldrActionResumeFile = 2
 const dlFldrActionNextFile = 3
 
-func (s *Server) TransferFile(conn net.Conn) error {
-       defer func() { _ = conn.Close() }()
+// 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)
 
        txBuf := make([]byte, 16)
 
        txBuf := make([]byte, 16)
-       _, err := conn.Read(txBuf)
-       if err != nil {
+       if _, err := io.ReadFull(rwc, txBuf); err != nil {
                return err
        }
 
        var t transfer
                return err
        }
 
        var t transfer
-       _, err = t.Write(txBuf)
-       if err != nil {
+       if _, err := t.Write(txBuf); err != nil {
                return err
        }
 
                return err
        }
 
-       transferRefNum := binary.BigEndian.Uint32(t.ReferenceNumber[:])
-       fileTransfer := s.FileTransfers[transferRefNum]
+       defer func() {
+               s.mux.Lock()
+               delete(s.fileTransfers, t.ReferenceNumber)
+               s.mux.Unlock()
+
+               // 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
+               // the server does.  This is gross and seems unnecessary.  TODO: Revisit?
+               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),
+       )
+
+       fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
+       if err != nil {
+               return err
+       }
 
        switch fileTransfer.Type {
 
        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 FileDownload:
        case FileDownload:
-               fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
-               if err != nil {
-                       return err
+               s.Stats.DownloadCounter += 1
+               s.Stats.DownloadsInProgress += 1
+               defer func() {
+                       s.Stats.DownloadsInProgress -= 1
+               }()
+
+               var dataOffset int64
+               if fileTransfer.fileResumeData != nil {
+                       dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
                }
 
                }
 
-               ffo, err := NewFlattenedFileObject(
-                       s.Config.FileRoot,
-                       fileTransfer.FilePath,
-                       fileTransfer.FileName,
-               )
+               fw, err := newFileWrapper(s.FS, fullPath, 0)
                if err != nil {
                        return err
                }
 
                if err != nil {
                        return err
                }
 
-               s.Logger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber, "RemoteAddr", conn.RemoteAddr().String())
+               rLogger.Info("File download started", "filePath", fullPath)
 
 
-               // Start by sending flat file object to client
-               if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
-                       return err
+               // if file transfer options are included, that means this is a "quick preview" request from a 1.5+ client
+               if fileTransfer.options == nil {
+                       _, err = io.Copy(rwc, fw.ffo)
+                       if err != nil {
+                               return err
+                       }
                }
 
                }
 
-               file, err := FS.Open(fullFilePath)
+               file, err := fw.dataForkReader()
                if err != nil {
                        return err
                }
 
                if err != nil {
                        return err
                }
 
-               sendBuffer := make([]byte, 1048576)
-               for {
-                       var bytesRead int
-                       if bytesRead, err = file.Read(sendBuffer); err == io.EOF {
-                               break
-                       }
-
-                       fileTransfer.BytesSent += bytesRead
+               br := bufio.NewReader(file)
+               if _, err := br.Discard(int(dataOffset)); err != nil {
+                       return err
+               }
 
 
-                       delete(s.FileTransfers, transferRefNum)
+               if _, err = io.Copy(rwc, io.TeeReader(br, fileTransfer.bytesSentCounter)); err != nil {
+                       return err
+               }
 
 
-                       if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
+               // if the client requested to resume transfer, do not send the resource fork header, or it will be appended into the fileWrapper data
+               if fileTransfer.fileResumeData == nil {
+                       err = binary.Write(rwc, binary.BigEndian, fw.rsrcForkHeader())
+                       if err != nil {
                                return err
                        }
                }
                                return err
                        }
                }
-       case FileUpload:
-               const buffSize = 1460
 
 
-               uploadBuf := make([]byte, buffSize)
-
-               _, err := conn.Read(uploadBuf)
+               rFile, err := fw.rsrcForkFile()
                if err != nil {
                if err != nil {
-                       return err
+                       return nil
                }
 
                }
 
-               ffo := ReadFlattenedFileObject(uploadBuf)
-               payloadLen := len(ffo.BinaryMarshal())
-               fileSize := int(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize))
-
-               destinationFile := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
-               s.Logger.Infow(
-                       "File upload started",
-                       "transactionRef", fileTransfer.ReferenceNumber,
-                       "RemoteAddr", conn.RemoteAddr().String(),
-                       "size", fileSize,
-                       "dstFile", destinationFile,
-               )
-
-               newFile, err := os.Create(destinationFile)
-               if err != nil {
+               if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
                        return err
                }
 
                        return err
                }
 
-               defer func() { _ = newFile.Close() }()
+       case FileUpload:
+               s.Stats.UploadCounter += 1
+               s.Stats.UploadsInProgress += 1
+               defer func() { s.Stats.UploadsInProgress -= 1 }()
+
+               var file *os.File
+
+               // A file upload has three possible cases:
+               // 1) Upload a new file
+               // 2) Resume a partially transferred file
+               // 3) Replace a fully uploaded file
+               //  We have to infer which case applies by inspecting what is already on the filesystem
+
+               // 1) Check for existing file:
+               _, err = os.Stat(fullPath)
+               if err == nil {
+                       return errors.New("existing file found at " + fullPath)
+               }
+               if errors.Is(err, fs.ErrNotExist) {
+                       // If not found, open or create a new .incomplete file
+                       file, err = os.OpenFile(fullPath+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
+                       if err != nil {
+                               return err
+                       }
+               }
 
 
-               if _, err := newFile.Write(uploadBuf[payloadLen:]); err != nil {
+               f, err := newFileWrapper(s.FS, fullPath, 0)
+               if err != nil {
                        return err
                }
                        return err
                }
-               receivedBytes := buffSize - payloadLen
 
 
-               for {
-                       if (fileSize - receivedBytes) < buffSize {
-                               s.Logger.Infow(
-                                       "File upload complete",
-                                       "transactionRef", fileTransfer.ReferenceNumber,
-                                       "RemoteAddr", conn.RemoteAddr().String(),
-                                       "size", fileSize,
-                                       "dstFile", destinationFile,
-                               )
+               rLogger.Info("File upload started", "dstFile", fullPath)
 
 
-                               if _, err := io.CopyN(newFile, conn, int64(fileSize-receivedBytes)); err != nil {
-                                       return fmt.Errorf("file transfer failed: %s", err)
-                               }
-                               return nil
+               rForkWriter := io.Discard
+               iForkWriter := io.Discard
+               if s.Config.PreserveResourceForks {
+                       rForkWriter, err = f.rsrcForkWriter()
+                       if err != nil {
+                               return err
                        }
 
                        }
 
-                       // Copy N bytes from conn to upload file
-                       n, err := io.CopyN(newFile, conn, buffSize)
+                       iForkWriter, err = f.infoForkWriter()
                        if err != nil {
                                return err
                        }
                        if err != nil {
                                return err
                        }
-                       receivedBytes += int(n)
                }
                }
+
+               if err := receiveFile(rwc, file, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
+                       s.Logger.Error(err.Error())
+               }
+
+               if err := file.Close(); err != nil {
+                       return err
+               }
+
+               if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
+                       return err
+               }
+
+               rLogger.Info("File upload complete", "dstFile", fullPath)
+
        case FolderDownload:
        case FolderDownload:
+               s.Stats.DownloadCounter += 1
+               s.Stats.DownloadsInProgress += 1
+               defer func() { s.Stats.DownloadsInProgress -= 1 }()
+
                // Folder Download flow:
                // 1. Get filePath from the transfer
                // 2. Iterate over files
                // Folder Download flow:
                // 1. Get filePath from the transfer
                // 2. Iterate over files
-               // 3. For each file:
-               //       Send file header to client
+               // 3. For each fileWrapper:
+               //       Send fileWrapper header to client
                // The client can reply in 3 ways:
                //
                // The client can reply in 3 ways:
                //
-               // 1. If type is an odd number (unknown type?), or file download for the current file is completed:
-               //              client sends []byte{0x00, 0x03} to tell the server to continue to the next file
+               // 1. If type is an odd number (unknown type?), or fileWrapper download for the current fileWrapper is completed:
+               //              client sends []byte{0x00, 0x03} to tell the server to continue to the next fileWrapper
                //
                //
-               // 2. If download of a file is to be resumed:
+               // 2. If download of a fileWrapper is to be resumed:
                //              client sends:
                //                      []byte{0x00, 0x02} // download folder action
                //                      [2]byte // Resume data size
                //              client sends:
                //                      []byte{0x00, 0x02} // download folder action
                //                      [2]byte // Resume data size
-               //                      []byte file resume data (see myField_FileResumeData)
+               //                      []byte fileWrapper resume data (see myField_FileResumeData)
                //
                //
-               // 3. Otherwise download of the file is requested and client sends []byte{0x00, 0x01}
+               // 3. Otherwise, download of the fileWrapper is requested and client sends []byte{0x00, 0x01}
                //
                // When download is requested (case 2 or 3), server replies with:
                //
                // When download is requested (case 2 or 3), server replies with:
-               //                      [4]byte - file size
+               //                      [4]byte - fileWrapper size
                //                      []byte  - Flattened File Object
                //
                //                      []byte  - Flattened File Object
                //
-               // After every file download, client could request next file with:
+               // After every fileWrapper download, client could request next fileWrapper with:
                //                      []byte{0x00, 0x03}
                //
                // This notifies the server to send the next item header
 
                //                      []byte{0x00, 0x03}
                //
                // This notifies the server to send the next item header
 
-               fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
-               if err != nil {
+               basePathLen := len(fullPath)
+
+               rLogger.Info("Start folder download", "path", fullPath)
+
+               nextAction := make([]byte, 2)
+               if _, err := io.ReadFull(rwc, nextAction); err != nil {
                        return err
                }
 
                        return err
                }
 
-               basePathLen := len(fullFilePath)
+               i := 0
+               err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
+                       s.Stats.DownloadCounter += 1
+                       i += 1
 
 
-               readBuffer := make([]byte, 1024)
+                       if err != nil {
+                               return err
+                       }
 
 
-               s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber, "RemoteAddr", conn.RemoteAddr())
+                       // skip dot files
+                       if strings.HasPrefix(info.Name(), ".") {
+                               return nil
+                       }
 
 
-               i := 0
-               _ = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, _ error) error {
-                       i += 1
-                       subPath := path[basePathLen:]
-                       s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())
+                       hlFile, err := newFileWrapper(s.FS, path, 0)
+                       if err != nil {
+                               return err
+                       }
 
 
-                       fileHeader := NewFileHeader(subPath, info.IsDir())
+                       subPath := path[basePathLen+1:]
+                       rLogger.Debug("Sending fileheader", "i", i, "path", path, "fullFilePath", fullPath, "subPath", subPath, "IsDir", info.IsDir())
 
                        if i == 1 {
                                return nil
                        }
 
 
                        if i == 1 {
                                return nil
                        }
 
-                       // Send the file header to client
-                       if _, err := conn.Write(fileHeader.Payload()); err != nil {
-                               s.Logger.Errorf("error sending file header: %v", err)
-                               return err
+                       fileHeader := NewFileHeader(subPath, info.IsDir())
+                       if _, err := io.Copy(rwc, &fileHeader); err != nil {
+                               return fmt.Errorf("error sending file header: %w", err)
                        }
 
                        // Read the client's Next Action request
                        }
 
                        // Read the client's Next Action request
-                       // TODO: Remove hardcoded behavior and switch behaviors based on the next action send
-                       if _, err := conn.Read(readBuffer); err != nil {
+                       if _, err := io.ReadFull(rwc, nextAction); err != nil {
                                return err
                        }
 
                                return err
                        }
 
-                       s.Logger.Infow("Client folder download action", "action", fmt.Sprintf("%X", readBuffer[0:2]))
+                       rLogger.Debug("Client folder download action", "action", fmt.Sprintf("%X", nextAction[0:2]))
 
 
-                       if info.IsDir() {
+                       var dataOffset int64
+
+                       switch nextAction[1] {
+                       case dlFldrActionResumeFile:
+                               // get size of resumeData
+                               resumeDataByteLen := make([]byte, 2)
+                               if _, err := io.ReadFull(rwc, resumeDataByteLen); err != nil {
+                                       return err
+                               }
+
+                               resumeDataLen := binary.BigEndian.Uint16(resumeDataByteLen)
+                               resumeDataBytes := make([]byte, resumeDataLen)
+                               if _, err := io.ReadFull(rwc, resumeDataBytes); err != nil {
+                                       return err
+                               }
+
+                               var frd FileResumeData
+                               if err := frd.UnmarshalBinary(resumeDataBytes); err != nil {
+                                       return err
+                               }
+                               dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
+                       case dlFldrActionNextFile:
+                               // client asked to skip this file
                                return nil
                        }
 
                                return nil
                        }
 
-                       splitPath := strings.Split(path, "/")
-
-                       ffo, err := NewFlattenedFileObject(
-                               strings.Join(splitPath[:len(splitPath)-1], "/"),
-                               nil,
-                               []byte(info.Name()),
-                       )
-                       if err != nil {
-                               return err
+                       if info.IsDir() {
+                               return nil
                        }
                        }
-                       s.Logger.Infow("File download started",
+
+                       rLogger.Info("File download started",
                                "fileName", info.Name(),
                                "fileName", info.Name(),
-                               "transactionRef", fileTransfer.ReferenceNumber,
-                               "RemoteAddr", conn.RemoteAddr().String(),
-                               "TransferSize", fmt.Sprintf("%x", ffo.TransferSize()),
+                               "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
                        )
 
                        // Send file size to client
                        )
 
                        // Send file size to client
-                       if _, err := conn.Write(ffo.TransferSize()); err != nil {
-                               s.Logger.Error(err)
+                       if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {
+                               s.Logger.Error(err.Error())
                                return err
                        }
 
                                return err
                        }
 
-                       // Send file bytes to client
-                       if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
-                               s.Logger.Error(err)
+                       // Send ffo bytes to client
+                       _, err = io.Copy(rwc, hlFile.ffo)
+                       if err != nil {
                                return err
                        }
 
                                return err
                        }
 
-                       file, err := FS.Open(path)
+                       file, err := s.FS.Open(path)
                        if err != nil {
                                return err
                        }
 
                        if err != nil {
                                return err
                        }
 
-                       sendBuffer := make([]byte, 1048576)
-                       totalBytesSent := len(ffo.BinaryMarshal())
+                       // wr := bufio.NewWriterSize(rwc, 1460)
+                       if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
+                               return err
+                       }
 
 
-                       for {
-                               bytesRead, err := file.Read(sendBuffer)
-                               if err == io.EOF {
-                                       // Read the client's Next Action request
-                                       // TODO: Remove hardcoded behavior and switch behaviors based on the next action send
-                                       if _, err := conn.Read(readBuffer); err != nil {
-                                               s.Logger.Errorf("error reading next action: %v", err)
-                                               return err
-                                       }
-                                       break
+                       if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
+                               err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
+                               if err != nil {
+                                       return err
                                }
 
                                }
 
-                               sentBytes, readErr := conn.Write(sendBuffer[:bytesRead])
-                               totalBytesSent += sentBytes
-                               if readErr != nil {
+                               rFile, err := hlFile.rsrcForkFile()
+                               if err != nil {
                                        return err
                                }
                                        return err
                                }
+
+                               if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
+                                       return err
+                               }
+                       }
+
+                       // Read the client's Next Action request.  This is always 3, I think?
+                       if _, err := io.ReadFull(rwc, nextAction); err != nil {
+                               return err
                        }
                        }
+
                        return nil
                })
 
                        return nil
                })
 
-       case FolderUpload:
-               dstPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
                if err != nil {
                        return err
                }
                if err != nil {
                        return err
                }
-               s.Logger.Infow(
+
+       case FolderUpload:
+               s.Stats.UploadCounter += 1
+               s.Stats.UploadsInProgress += 1
+               defer func() { s.Stats.UploadsInProgress -= 1 }()
+               rLogger.Info(
                        "Folder upload started",
                        "Folder upload started",
-                       "transactionRef", fileTransfer.ReferenceNumber,
-                       "RemoteAddr", conn.RemoteAddr().String(),
-                       "dstPath", dstPath,
-                       "TransferSize", fmt.Sprintf("%x", fileTransfer.TransferSize),
+                       "dstPath", fullPath,
+                       "TransferSize", binary.BigEndian.Uint32(fileTransfer.TransferSize),
                        "FolderItemCount", fileTransfer.FolderItemCount,
                )
 
                // Check if the target folder exists.  If not, create it.
                        "FolderItemCount", fileTransfer.FolderItemCount,
                )
 
                // Check if the target folder exists.  If not, create it.
-               if _, err := FS.Stat(dstPath); os.IsNotExist(err) {
-                       s.Logger.Infow("Creating target path", "dstPath", dstPath)
-                       if err := FS.Mkdir(dstPath, 0777); err != nil {
-                               s.Logger.Error(err)
+               if _, err := s.FS.Stat(fullPath); os.IsNotExist(err) {
+                       if err := s.FS.Mkdir(fullPath, 0777); err != nil {
+                               return err
                        }
                }
 
                        }
                }
 
-               readBuffer := make([]byte, 1024)
-
                // Begin the folder upload flow by sending the "next file action" to client
                // Begin the folder upload flow by sending the "next file action" to client
-               if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
+               if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
                        return err
                }
 
                fileSize := make([]byte, 4)
                        return err
                }
 
                fileSize := make([]byte, 4)
-               itemCount := binary.BigEndian.Uint16(fileTransfer.FolderItemCount)
 
 
-               for i := uint16(0); i < itemCount; i++ {
-                       if _, err := conn.Read(readBuffer); err != nil {
+               for i := 0; i < fileTransfer.ItemCount(); i++ {
+                       s.Stats.UploadCounter += 1
+
+                       var fu folderUpload
+                       if _, err := io.ReadFull(rwc, fu.DataSize[:]); err != nil {
+                               return err
+                       }
+                       if _, err := io.ReadFull(rwc, fu.IsFolder[:]); err != nil {
+                               return err
+                       }
+                       if _, err := io.ReadFull(rwc, fu.PathItemCount[:]); err != nil {
+                               return err
+                       }
+
+                       fu.FileNamePath = make([]byte, binary.BigEndian.Uint16(fu.DataSize[:])-4) // -4 to subtract the path separator bytes
+
+                       if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
                                return err
                        }
                                return err
                        }
-                       fu := readFolderUpload(readBuffer)
 
 
-                       s.Logger.Infow(
+                       rLogger.Info(
                                "Folder upload continued",
                                "Folder upload continued",
-                               "transactionRef", fmt.Sprintf("%x", fileTransfer.ReferenceNumber),
-                               "RemoteAddr", conn.RemoteAddr().String(),
                                "FormattedPath", fu.FormattedPath(),
                                "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
                                "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
                        )
 
                        if fu.IsFolder == [2]byte{0, 1} {
                                "FormattedPath", fu.FormattedPath(),
                                "IsFolder", fmt.Sprintf("%x", fu.IsFolder),
                                "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),
                        )
 
                        if fu.IsFolder == [2]byte{0, 1} {
-                               if _, err := os.Stat(dstPath + "/" + fu.FormattedPath()); os.IsNotExist(err) {
-                                       s.Logger.Infow("Target path does not exist; Creating...", "dstPath", dstPath)
-                                       if err := os.Mkdir(dstPath+"/"+fu.FormattedPath(), 0777); err != nil {
-                                               s.Logger.Error(err)
+                               if _, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath())); os.IsNotExist(err) {
+                                       if err := os.Mkdir(filepath.Join(fullPath, fu.FormattedPath()), 0777); err != nil {
+                                               return err
                                        }
                                }
 
                                // Tell client to send next file
                                        }
                                }
 
                                // Tell client to send next file
-                               if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
-                                       s.Logger.Error(err)
+                               if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
                                        return err
                                }
                        } else {
                                        return err
                                }
                        } else {
-                               // TODO: Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
-                               // TODO: Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
-                               // Send dlFldrAction_SendFile to client to begin transfer
-                               if _, err := conn.Write([]byte{0, dlFldrActionSendFile}); err != nil {
-                                       return err
-                               }
+                               nextAction := dlFldrActionSendFile
 
 
-                               if _, err := conn.Read(fileSize); err != nil {
-                                       fmt.Println("Error reading:", err.Error()) // TODO: handle
+                               // Check if we have the full file already.  If so, send dlFldrAction_NextFile to client to skip.
+                               _, err = os.Stat(filepath.Join(fullPath, fu.FormattedPath()))
+                               if err != nil && !errors.Is(err, fs.ErrNotExist) {
+                                       return err
                                }
                                }
-
-                               s.Logger.Infow("Starting file transfer", "fileNum", i+1, "totalFiles", itemCount, "fileSize", fileSize)
-
-                               if err := transferFile(conn, dstPath+"/"+fu.FormattedPath()); err != nil {
-                                       s.Logger.Error(err)
+                               if err == nil {
+                                       nextAction = dlFldrActionNextFile
                                }
 
                                }
 
-                               // Tell client to send next file
-                               if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
-                                       s.Logger.Error(err)
+                               //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
+                               incompleteFile, err := os.Stat(filepath.Join(fullPath, fu.FormattedPath()+incompleteFileSuffix))
+                               if err != nil && !errors.Is(err, fs.ErrNotExist) {
                                        return err
                                }
                                        return err
                                }
+                               if err == nil {
+                                       nextAction = dlFldrActionResumeFile
+                               }
 
 
-                               // Client sends "MACR" after the file.  Read and discard.
-                               // TODO: This doesn't seem to be documented.  What is this?  Maybe resource fork?
-                               if _, err := conn.Read(readBuffer); err != nil {
+                               if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
                                        return err
                                }
                                        return err
                                }
-                       }
-               }
-               s.Logger.Infof("Folder upload complete")
-       }
 
 
-       return nil
-}
+                               switch nextAction {
+                               case dlFldrActionNextFile:
+                                       continue
+                               case dlFldrActionResumeFile:
+                                       offset := make([]byte, 4)
+                                       binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
 
 
-func transferFile(conn net.Conn, dst string) error {
-       const buffSize = 1024
-       buf := make([]byte, buffSize)
+                                       file, err := os.OpenFile(fullPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+                                       if err != nil {
+                                               return err
+                                       }
 
 
-       // Read first chunk of bytes from conn; this will be the Flat File Object and initial chunk of file bytes
-       if _, err := conn.Read(buf); err != nil {
-               return err
-       }
-       ffo := ReadFlattenedFileObject(buf)
-       payloadLen := len(ffo.BinaryMarshal())
-       fileSize := int(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize))
+                                       fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
 
 
-       newFile, err := os.Create(dst)
-       if err != nil {
-               return err
-       }
-       defer func() { _ = newFile.Close() }()
-       if _, err := newFile.Write(buf[payloadLen:]); err != nil {
-               return err
-       }
-       receivedBytes := buffSize - payloadLen
+                                       b, _ := fileResumeData.BinaryMarshal()
 
 
-       for {
-               if (fileSize - receivedBytes) < buffSize {
-                       _, err := io.CopyN(newFile, conn, int64(fileSize-receivedBytes))
-                       return err
-               }
+                                       bs := make([]byte, 2)
+                                       binary.BigEndian.PutUint16(bs, uint16(len(b)))
 
 
-               // Copy N bytes from conn to upload file
-               n, err := io.CopyN(newFile, conn, buffSize)
-               if err != nil {
-                       return err
+                                       if _, err := rwc.Write(append(bs, b...)); err != nil {
+                                               return err
+                                       }
+
+                                       if _, err := io.ReadFull(rwc, fileSize); err != nil {
+                                               return err
+                                       }
+
+                                       if err := receiveFile(rwc, file, io.Discard, io.Discard, fileTransfer.bytesSentCounter); err != nil {
+                                               s.Logger.Error(err.Error())
+                                       }
+
+                                       err = os.Rename(fullPath+"/"+fu.FormattedPath()+".incomplete", fullPath+"/"+fu.FormattedPath())
+                                       if err != nil {
+                                               return err
+                                       }
+
+                               case dlFldrActionSendFile:
+                                       if _, err := io.ReadFull(rwc, fileSize); err != nil {
+                                               return err
+                                       }
+
+                                       filePath := filepath.Join(fullPath, fu.FormattedPath())
+
+                                       hlFile, err := newFileWrapper(s.FS, filePath, 0)
+                                       if err != nil {
+                                               return err
+                                       }
+
+                                       rLogger.Info("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))
+
+                                       incWriter, err := hlFile.incFileWriter()
+                                       if err != nil {
+                                               return err
+                                       }
+
+                                       rForkWriter := io.Discard
+                                       iForkWriter := io.Discard
+                                       if s.Config.PreserveResourceForks {
+                                               iForkWriter, err = hlFile.infoForkWriter()
+                                               if err != nil {
+                                                       return err
+                                               }
+
+                                               rForkWriter, err = hlFile.rsrcForkWriter()
+                                               if err != nil {
+                                                       return err
+                                               }
+                                       }
+                                       if err := receiveFile(rwc, incWriter, rForkWriter, iForkWriter, fileTransfer.bytesSentCounter); err != nil {
+                                               return err
+                                       }
+
+                                       if err := os.Rename(filePath+".incomplete", filePath); err != nil {
+                                               return err
+                                       }
+                               }
+
+                               // Tell client to send next fileWrapper
+                               if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
+                                       return err
+                               }
+                       }
                }
                }
-               receivedBytes += int(n)
+               rLogger.Info("Folder upload complete")
        }
        }
-}
 
 
-// sortedClients is a utility function that takes a map of *ClientConn and returns a sorted slice of the values.
-// The purpose of this is to ensure that the ordering of client connections is deterministic so that test assertions work.
-func sortedClients(unsortedClients map[uint16]*ClientConn) (clients []*ClientConn) {
-       for _, c := range unsortedClients {
-               clients = append(clients, c)
-       }
-       sort.Sort(byClientID(clients))
-       return clients
+       return nil
 }
 }
Friendship Quest remix of mobius, a hotline server in go #cli