Minor cleanup

[rbdr/mobius] / hotline / server.go

diff --git a/hotline/server.go b/hotline/server.go
index 8e0fb5086056bcb0b3ba60e000bbaec867f409ce..852b7727b5da640d867b752cd69dfb1311d37a6c 100644 (file)
--- a/hotline/server.go
+++ b/hotline/server.go
@@ -1,63 +1,74 @@
 package hotline
 
 import (
 package hotline
 
 import (

+       "bufio"

        "bytes"
        "context"
        "encoding/binary"
        "errors"
        "fmt"
        "bytes"
        "context"
        "encoding/binary"
        "errors"
        "fmt"

+       "github.com/go-playground/validator/v10"

        "go.uber.org/zap"
        "go.uber.org/zap"

+       "gopkg.in/yaml.v3"

        "io"
        "io"

+       "io/fs"

        "io/ioutil"
        "io/ioutil"

-       "log"

        "math/big"
        "math/rand"
        "net"
        "os"
        "math/big"
        "math/rand"
        "net"
        "os"

-       "path"

        "path/filepath"
        "path/filepath"

-       "runtime/debug"
-       "sort"

        "strings"
        "sync"
        "time"
        "strings"
        "sync"
        "time"

-
-       "golang.org/x/crypto/bcrypt"
-       "gopkg.in/yaml.v2"

 )
 
 )
 

+type contextKey string
+
+var contextKeyReq = contextKey("req")
+
+type requestCtx struct {
+       remoteAddr string
+       login      string
+       name       string
+}
+

 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
 )
 
 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
 )
 

+var nostalgiaVersion = []byte{0, 0, 2, 0x2c} // version ID used by the Nostalgia client
+

 type Server struct {
        Port          int
        Accounts      map[string]*Account
        Agreement     []byte
        Clients       map[uint16]*ClientConn
 type Server struct {
        Port          int
        Accounts      map[string]*Account
        Agreement     []byte
        Clients       map[uint16]*ClientConn

-       FlatNews      []byte
-       ThreadedNews  *ThreadedNews
-       FileTransfers map[uint32]*FileTransfer
+       fileTransfers map[[4]byte]*FileTransfer
+

        Config        *Config
        ConfigDir     string
        Logger        *zap.SugaredLogger
        PrivateChats  map[uint32]*PrivateChat
        NextGuestID   *uint16
        Config        *Config
        ConfigDir     string
        Logger        *zap.SugaredLogger
        PrivateChats  map[uint32]*PrivateChat
        NextGuestID   *uint16

-       TrackerPassID []byte
+       TrackerPassID [4]byte

        Stats         *Stats
 
        Stats         *Stats
 

-       APIListener  net.Listener
-       FileListener net.Listener
-
-       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

 }
 
 type PrivateChat struct {
 }
 
 type PrivateChat struct {


@@ -66,27 +77,41 @@ 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.Infow("Hotline server started",
+               "version", VERSION,
+               "API port", fmt.Sprintf(":%v", s.Port),
+               "Transfer port", fmt.Sprintf(":%v", 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.Port))
+               if err != nil {
+                       s.Logger.Fatal(err)
+               }
+
+               s.Logger.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.Port+1))
+               if err != nil {
+                       s.Logger.Fatal(err)
+
+               }
+
+               s.Logger.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 {


@@ -94,7 +119,16 @@ func (s *Server) ServeFileTransfers(ln net.Listener) error {
                }
 
                go func() {
                }
 
                go func() {

-                       if err := s.TransferFile(conn); err != nil {
+                       defer func() { _ = conn.Close() }()
+
+                       err = s.handleFileTransfer(
+                               context.WithValue(ctx, contextKeyReq, requestCtx{
+                                       remoteAddr: conn.RemoteAddr().String(),
+                               }),
+                               conn,
+                       )
+
+                       if err != nil {

                                s.Logger.Errorw("file transfer error", "reason", err)
                        }
                }()
                                s.Logger.Errorw("file transfer error", "reason", err)
                        }
                }()


@@ -102,7 +136,6 @@ func (s *Server) ServeFileTransfers(ln net.Listener) error {
 }
 
 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


@@ -110,55 +143,52 @@ func (s *Server) sendTransaction(t Transaction) error {
 
        s.mux.Lock()
        client := s.Clients[uint16(clientID)]
 
        s.mux.Lock()
        client := s.Clients[uint16(clientID)]

-       s.mux.Unlock()

        if client == nil {
        if client == nil {

-               return errors.New("invalid client")
+               return fmt.Errorf("invalid client id %v", *t.clientID)

        }
        }

-       userName := string(client.UserName)
-       login := client.Account.Login

 
 

-       handler := TransactionHandlers[requestNum]
+       s.mux.Unlock()

 
        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 {
+
+       if _, err := client.Connection.Write(b); 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.Errorw("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 {
                        s.Logger.Errorw("error accepting connection", "err", err)
                }
 
        for {
                conn, err := ln.Accept()
                if err != nil {
                        s.Logger.Errorw("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.Infow("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.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
                                } else {
                                if err == io.EOF {
                                        s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
                                } else {


@@ -170,17 +200,17 @@ func (s *Server) Serve(ctx context.Context, cancelRoot context.CancelFunc, ln ne
 }
 
 const (
 }
 
 const (

-       agreementFile    = "Agreement.txt"
+       agreementFile = "Agreement.txt"

 )
 
 // 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 string, netPort int, logger *zap.SugaredLogger, FS FileStore) (*Server, error) {

        server := Server{
                Port:          netPort,
                Accounts:      make(map[string]*Account),
                Config:        new(Config),
                Clients:       make(map[uint16]*ClientConn),
        server := Server{
                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,
                PrivateChats:  make(map[uint32]*PrivateChat),
                ConfigDir:     configDir,
                Logger:        logger,


@@ -188,71 +218,66 @@ func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredL
                outbox:        make(chan Transaction),
                Stats:         &Stats{StartTime: time.Now()},
                ThreadedNews:  &ThreadedNews{},
                outbox:        make(chan Transaction),
                Stats:         &Stats{StartTime: time.Now()},
                ThreadedNews:  &ThreadedNews{},

-               TrackerPassID: make([]byte, 4),
-       }
-
-       ln, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
-       if err != nil {
-               return nil, err
+               FS:            FS,
+               banList:       make(map[string]*time.Time),

        }
        }

-       server.APIListener = ln

 
 

-       if netPort != 0 {
-               netPort += 1
-       }
-
-       ln2, err := net.Listen("tcp", fmt.Sprintf("%s:%v", netInterface, netPort))
-       server.FileListener = ln2
-       if err != nil {
-               return nil, err
-       }
+       var err error

 
        // generate a new random passID for tracker registration
 
        // generate a new random passID for tracker registration

-       if _, err := rand.Read(server.TrackerPassID); err != nil {
+       if _, err := rand.Read(server.TrackerPassID[:]); 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 {
+       server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
+       if err != nil {

                return nil, err
        }
 
                return nil, err
        }
 

-       if server.FlatNews, err = os.ReadFile(configDir + "MessageBoard.txt"); err != nil {
+       if server.FlatNews, err = os.ReadFile(filepath.Join(configDir, "MessageBoard.txt")); err != nil {

                return nil, err
        }
 
                return nil, err
        }
 

-       if err := server.loadThreadedNews(configDir + "ThreadedNews.yaml"); err != nil {
+       // 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 err := server.loadThreadedNews(filepath.Join(configDir, "ThreadedNews.yaml")); err != nil {

                return nil, err
        }
 
                return nil, err
        }
 

-       if err := server.loadConfig(configDir + "config.yaml"); err != nil {
+       if err := server.loadConfig(filepath.Join(configDir, "config.yaml")); err != nil {

                return nil, err
        }
 
                return nil, err
        }
 

-       if err := server.loadAccounts(configDir + "Users/"); err != nil {
+       if err := server.loadAccounts(filepath.Join(configDir, "Users/")); err != nil {

                return nil, err
        }
 
                return nil, err
        }
 

-       server.Config.FileRoot = configDir + "Files/"
+       server.Config.FileRoot = filepath.Join(configDir, "Files")

 
        *server.NextGuestID = 1
 
        if server.Config.EnableTrackerRegistration {
 
        *server.NextGuestID = 1
 
        if server.Config.EnableTrackerRegistration {

+               server.Logger.Infow(
+                       "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(),
                                        UserCount:   server.userCount(),

-                                       PassID:      server.TrackerPassID,
+                                       PassID:      server.TrackerPassID[:],

                                        Name:        server.Config.Name,
                                        Description: server.Config.Description,
                                }
                                        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 {
                                                server.Logger.Errorw("unable to register with tracker %v", "error", err)
                                        }
                                        if err := register(t, tr); err != nil {
                                                server.Logger.Errorw("unable to register with tracker %v", "error", err)
                                        }

+                                       server.Logger.Debugw("Sent Tracker registration", "addr", t)

                                }
 
                                time.Sleep(trackerUpdateFrequency * time.Second)
                                }
 
                                time.Sleep(trackerUpdateFrequency * time.Second)


@@ -279,20 +304,20 @@ func (s *Server) keepaliveHandler() {
                s.mux.Lock()
 
                for _, c := range s.Clients {
                s.mux.Lock()
 
                for _, c := range s.Clients {

-                       *c.IdleTime += idleCheckInterval
-                       if *c.IdleTime > userIdleSeconds && !c.Idle {
+                       c.IdleTime += idleCheckInterval
+                       if c.IdleTime > userIdleSeconds && !c.Idle {

                                c.Idle = true
 
                                c.Idle = true
 

-                               flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(*c.Flags)))
+                               flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))

                                flagBitmap.SetBit(flagBitmap, userFlagAway, 1)
                                flagBitmap.SetBit(flagBitmap, userFlagAway, 1)

-                               binary.BigEndian.PutUint16(*c.Flags, uint16(flagBitmap.Int64()))
+                               binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))

 
                                c.sendAll(
                                        tranNotifyChangeUser,
                                        NewField(fieldUserID, *c.ID),
 
                                c.sendAll(
                                        tranNotifyChangeUser,
                                        NewField(fieldUserID, *c.ID),

-                                       NewField(fieldUserFlags, *c.Flags),
+                                       NewField(fieldUserFlags, c.Flags),

                                        NewField(fieldUserName, c.UserName),
                                        NewField(fieldUserName, c.UserName),

-                                       NewField(fieldUserIconID, *c.Icon),
+                                       NewField(fieldUserIconID, c.Icon),

                                )
                        }
                }
                                )
                        }
                }


@@ -300,43 +325,66 @@ 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 = ioutil.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{},
-               IdleTime:   new(int),
-               AutoReply:  &[]byte{},
-               Transfers:  make(map[int][]*FileTransfer),
+               Version:    []byte{},
+               AutoReply:  []byte{},
+               transfers:  map[int]map[[4]byte]*FileTransfer{},
+               Agreed:     false,
+               RemoteAddr: remoteAddr,
+       }
+       clientConn.transfers = map[int]map[[4]byte]*FileTransfer{
+               FileDownload:   {},
+               FileUpload:     {},
+               FolderDownload: {},
+               FolderUpload:   {},
+               bannerDownload: {},

        }
        }

+

        *s.NextGuestID++
        ID := *s.NextGuestID
 
        *s.NextGuestID++
        ID := *s.NextGuestID
 

-       *clientConn.IdleTime = 0
-

        binary.BigEndian.PutUint16(*clientConn.ID, ID)
        s.Clients[ID] = clientConn
 
        binary.BigEndian.PutUint16(*clientConn.ID, ID)
        s.Clients[ID] = clientConn
 


@@ -344,7 +392,7 @@ 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()
 


@@ -352,7 +400,7 @@ 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 {
        }
        out, err := yaml.Marshal(&account)
        if err != nil {


@@ -360,7 +408,38 @@ func (s *Server) NewUser(login, name, password string, access []byte) error {
        }
        s.Accounts[login] = &account
 
        }
        s.Accounts[login] = &account
 

-       return ioutil.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
+       return s.FS.WriteFile(filepath.Join(s.ConfigDir, "Users", login+".yaml"), out, 0666)
+}
+
+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", login+".yaml"), filepath.Join(s.ConfigDir, "Users", newLogin+".yaml"))
+               if err != nil {
+                       return err
+               }
+               s.Accounts[newLogin] = s.Accounts[login]
+               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


@@ -370,7 +449,7 @@ func (s *Server) DeleteUser(login string) error {
 
        delete(s.Accounts, login)
 
 
        delete(s.Accounts, login)
 

-       return os.Remove(s.ConfigDir + "Users/" + login + ".yaml")
+       return s.FS.Remove(filepath.Join(s.ConfigDir, "Users", login+".yaml"))

 }
 
 func (s *Server) connectedUsers() []Field {
 }
 
 func (s *Server) connectedUsers() []Field {


@@ -378,11 +457,14 @@ func (s *Server) connectedUsers() []Field {
        defer s.mux.Unlock()
 
        var connectedUsers []Field
        defer s.mux.Unlock()
 
        var connectedUsers []Field

-       for _, c := range s.Clients {
+       for _, c := range sortedClients(s.Clients) {
+               if !c.Agreed {
+                       continue
+               }

                user := User{
                        ID:    *c.ID,
                user := User{
                        ID:    *c.ID,

-                       Icon:  *c.Icon,
-                       Flags: *c.Flags,
+                       Icon:  c.Icon,
+                       Flags: c.Flags,

                        Name:  string(c.UserName),
                }
                connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))
                        Name:  string(c.UserName),
                }
                connectedUsers = append(connectedUsers, NewField(fieldUsernameWithInfo, user.Payload()))


@@ -390,6 +472,16 @@ func (s *Server) connectedUsers() []Field {
        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)


@@ -397,14 +489,13 @@ 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
        }


@@ -414,14 +505,13 @@ func (s *Server) loadAccounts(userDir string) error {
        }
 
        for _, file := range matches {
        }
 
        for _, file := range matches {

-               fh, err := os.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 err
                }


@@ -432,61 +522,75 @@ func (s *Server) loadAccounts(userDir string) error {
 }
 
 func (s *Server) loadConfig(path string) error {
 }
 
 func (s *Server) loadConfig(path string) error {

-       fh, err := os.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 {
-               return err
-       }
-       if err != nil {
+       if err := Handshake(rwc); err != nil {

                return err
        }
 
                return err
        }
 

-       clientLogin, _, err := ReadTransaction(buf[:readLen])
-       if err != nil {
+       // Create a new scanner for parsing incoming bytes into transaction tokens
+       scanner := bufio.NewScanner(rwc)
+       scanner.Split(transactionScanner)
+
+       scanner.Scan()
+
+       var clientLogin Transaction
+       if _, err := clientLogin.Write(scanner.Bytes()); err != nil {

                return err
        }
 
                return err
        }
 

-       c := s.NewClientConn(conn)
-       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()
+       c := s.NewClientConn(rwc, remoteAddr)
+
+       // check if remoteAddr is present in the ban list
+       if banUntil, ok := s.banList[strings.Split(remoteAddr, ":")[0]]; ok {
+               // permaban
+               if banUntil == nil {
+                       s.outbox <- *NewTransaction(
+                               tranServerMsg,
+                               c.ID,
+                               NewField(fieldData, []byte("You are permanently banned on this server")),
+                               NewField(fieldChatOptions, []byte{0, 0}),
+                       )
+                       time.Sleep(1 * time.Second)
+                       return nil
+               } else if time.Now().Before(*banUntil) {
+                       s.outbox <- *NewTransaction(
+                               tranServerMsg,
+                               c.ID,
+                               NewField(fieldData, []byte("You are temporarily banned on this server")),
+                               NewField(fieldChatOptions, []byte{0, 0}),
+                       )
+                       time.Sleep(1 * time.Second)
+                       return nil

                }
                }

-       }()
+
+       }
+       defer c.Disconnect()

 
        encodedLogin := clientLogin.GetField(fieldUserLogin).Data
        encodedPassword := clientLogin.GetField(fieldUserPassword).Data
 
        encodedLogin := clientLogin.GetField(fieldUserLogin).Data
        encodedPassword := clientLogin.GetField(fieldUserPassword).Data

-       *c.Version = clientLogin.GetField(fieldVersion).Data
+       c.Version = clientLogin.GetField(fieldVersion).Data

 
        var login string
        for _, char := range encodedLogin {
 
        var login string
        for _, char := range encodedLogin {


@@ -496,106 +600,101 @@ 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.Infow("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
+
+               return nil

        }
 
        if clientLogin.GetField(fieldUserIconID).Data != nil {
        }
 
        if clientLogin.GetField(fieldUserIconID).Data != nil {

-               *c.Icon = clientLogin.GetField(fieldUserIconID).Data
+               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,
+       s.outbox <- c.NewReply(&clientLogin,

                NewField(fieldVersion, []byte{0x00, 0xbe}),
                NewField(fieldVersion, []byte{0x00, 0xbe}),

-               NewField(fieldCommunityBannerID, []byte{0x00, 0x01}),
+               NewField(fieldCommunityBannerID, []byte{0, 0}),

                NewField(fieldServerName, []byte(s.Config.Name)),
        )
 
        // Send user access privs so client UI knows how to behave
                NewField(fieldServerName, []byte(s.Config.Name)),
        )
 
        // 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))
+       }

 
 

-       if _, err := c.notifyNewUserHasJoined(); err != nil {
-               return err
+       // Used simplified hotline v1.2.3 login flow for clients that do not send login info in tranAgreed
+       if c.Version == nil || bytes.Equal(c.Version, nostalgiaVersion) {
+               c.Agreed = true
+               c.logger = c.logger.With("name", string(c.UserName))
+               c.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(c.Version); return i }()))
+
+               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.LoginCount += 1
 

-       const readBuffSize = 1024000 // 1KB - TODO: what should this be?
-       const maxTranSize = 1024000
-       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)
+               if err := c.handleTransaction(t); err != nil {
+                       c.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)
-                       }
-               }
-       }
-}
-
-func hashAndSalt(pwd []byte) string {
-       // Use GenerateFromPassword to hash & salt pwd.
-       // MinCost is just an integer constant provided by the bcrypt
-       // package along with DefaultCost & MaxCost.
-       // The cost can be any value you want provided it isn't lower
-       // than the MinCost (4)
-       hash, err := bcrypt.GenerateFromPassword(pwd, bcrypt.MinCost)
-       if err != nil {
-               log.Println(err)

        }
        }

-       // GenerateFromPassword returns a byte slice so we need to
-       // convert the bytes to a string and return it
-       return string(hash)
-}
-
-// 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 {


@@ -619,424 +718,501 @@ 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)

 
 

-       buf := make([]byte, 1024)
-       if _, err := conn.Read(buf); err != nil {
+       txBuf := make([]byte, 16)
+       if _, err := io.ReadFull(rwc, txBuf); err != nil {

                return err
        }
 
        var t transfer
                return err
        }
 
        var t transfer

-       _, err := t.Write(buf[:16])
-       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()
+
+       }()
+
+       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 := s.bannerDownload(rwc); err != nil {
+                       return err
+               }

        case FileDownload:
        case FileDownload:

-               fullFilePath := fmt.Sprintf("%v/%v", s.Config.FileRoot+string(fileTransfer.FilePath), string(fileTransfer.FileName))
+               s.Stats.DownloadCounter += 1

 
 

-               ffo, err := NewFlattenedFileObject(
-                       s.Config.FileRoot+string(fileTransfer.FilePath),
-                       string(fileTransfer.FileName),
-               )
+               var dataOffset int64
+               if fileTransfer.fileResumeData != nil {
+                       dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
+               }
+
+               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.Infow("File download started", "filePath", fullPath)

 
 

-               // Start by sending flat file object to client
-               if _, err := conn.Write(ffo.Payload()); 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 {
+                       // Start by sending flat file object to client
+                       if _, err := rwc.Write(fw.ffo.BinaryMarshal()); err != nil {
+                               return err
+                       }

                }
 
                }
 

-               file, err := os.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:
-               if _, err := conn.Read(buf); err != nil {
-                       return err
-               }
-
-               ffo := ReadFlattenedFileObject(buf)
-               payloadLen := len(ffo.Payload())
-               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)
+               rFile, err := fw.rsrcForkFile()

                if err != nil {
                if err != nil {

+                       return 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
+
+               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

 
 

-               const buffSize = 1024
+               // 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(buf[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,
-                               )

 
 

-                               if _, err := io.CopyN(newFile, conn, int64(fileSize-receivedBytes)); err != nil {
-                                       return fmt.Errorf("file transfer failed: %s", err)
-                               }
-                               return nil
+               rLogger.Infow("File upload started", "dstFile", fullPath)
+
+               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)
+               }
+
+               if err := file.Close(); err != nil {
+                       return err
+               }
+
+               if err := s.FS.Rename(fullPath+".incomplete", fullPath); err != nil {
+                       return err
+               }
+
+               rLogger.Infow("File upload complete", "dstFile", fullPath)

        case FolderDownload:
                // Folder Download flow:
                // 1. Get filePath from the transfer
                // 2. Iterate over files
        case FolderDownload:
                // 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
 

-               var fh FilePath
-               _ = fh.UnmarshalBinary(fileTransfer.FilePath)
-               fullFilePath := fmt.Sprintf("%v/%v", s.Config.FileRoot+fh.String(), string(fileTransfer.FileName))
-
-               basePathLen := len(fullFilePath)
+               basePathLen := len(fullPath)

 
 

-               readBuffer := make([]byte, 1024)
+               rLogger.Infow("Start folder download", "path", fullPath)

 
 

-               s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber, "RemoteAddr", conn.RemoteAddr())
+               nextAction := make([]byte, 2)
+               if _, err := io.ReadFull(rwc, nextAction); err != nil {
+                       return err
+               }

 
                i := 0
 
                i := 0

-               _ = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, _ error) error {
+               err = filepath.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
+                       s.Stats.DownloadCounter += 1

                        i += 1
                        i += 1

-                       subPath := path[basePathLen:]
-                       s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())

 
 

-                       fileHeader := NewFileHeader(subPath, info.IsDir())
+                       if err != nil {
+                               return err
+                       }
+
+                       // skip dot files
+                       if strings.HasPrefix(info.Name(), ".") {
+                               return nil
+                       }
+
+                       hlFile, err := newFileWrapper(s.FS, path, 0)
+                       if err != nil {
+                               return err
+                       }
+
+                       subPath := path[basePathLen+1:]
+                       rLogger.Debugw("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 {
+                       fileHeader := NewFileHeader(subPath, info.IsDir())
+
+                       // Send the fileWrapper header to client
+                       if _, err := rwc.Write(fileHeader.Payload()); err != nil {

                                s.Logger.Errorf("error sending file header: %v", err)
                                return err
                        }
 
                        // Read the client's Next Action request
                                s.Logger.Errorf("error sending file header: %v", err)
                                return err
                        }
 
                        // 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)
+                       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.Debugw("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, "/")
-                       //strings.Join(splitPath[:len(splitPath)-1], "/")
-
-                       ffo, err := NewFlattenedFileObject(strings.Join(splitPath[:len(splitPath)-1], "/"), info.Name())
-                       if err != nil {
-                               return err
+                       if info.IsDir() {
+                               return nil

                        }
                        }

-                       s.Logger.Infow("File download started",
+
+                       rLogger.Infow("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 {
+                       if _, err := rwc.Write(hlFile.ffo.TransferSize(dataOffset)); err != nil {

                                s.Logger.Error(err)
                                return err
                        }
 
                                s.Logger.Error(err)
                                return err
                        }
 

-                       // Send file bytes to client
-                       if _, err := conn.Write(ffo.Payload()); err != nil {
+                       // Send ffo bytes to client
+                       if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {

                                s.Logger.Error(err)
                                return err
                        }
 
                                s.Logger.Error(err)
                                return err
                        }
 

-                       file, err := os.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.Payload())
+                       // 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
+                               }
+
+                               rFile, err := hlFile.rsrcForkFile()
+                               if err != nil {
+                                       return err

                                }
 
                                }
 

-                               sentBytes, readErr := conn.Write(sendBuffer[:bytesRead])
-                               totalBytesSent += sentBytes
-                               if readErr != nil {
+                               if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {

                                        return err
                                }
                        }
                                        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
                })
 

+               if err != nil {
+                       return err
+               }
+

        case FolderUpload:
        case FolderUpload:

-               dstPath := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
-               s.Logger.Infow(
+               rLogger.Infow(

                        "Folder upload started",
                        "Folder upload started",

-                       "transactionRef", fileTransfer.ReferenceNumber,
-                       "RemoteAddr", conn.RemoteAddr().String(),
-                       "dstPath", dstPath,
-                       "TransferSize", 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 := os.Stat(dstPath); os.IsNotExist(err) {
-                       s.Logger.Infow("Target path does not exist; Creating...", "dstPath", dstPath)
-                       if err := os.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
                        }
                                return err
                        }

-                       fu := readFolderUpload(readBuffer)
+                       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

 
 

-                       s.Logger.Infow(
+                       if _, err := io.ReadFull(rwc, fu.FileNamePath); err != nil {
+                               return err
+                       }
+
+                       rLogger.Infow(

                                "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),
                                "FormattedPath", fu.FormattedPath(),
                                "IsFolder", fmt.Sprintf("%x", fu.IsFolder),

-                               "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount),
+                               "PathItemCount", binary.BigEndian.Uint16(fu.PathItemCount[:]),

                        )
 
                        )
 

-                       if bytes.Equal(fu.IsFolder, []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 fu.IsFolder == [2]byte{0, 1} {
+                               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 {
+                               nextAction := dlFldrActionSendFile
+
+                               // 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
                                }
                                        return err
                                }

-
-                               if _, err := conn.Read(fileSize); err != nil {
-                                       fmt.Println("Error reading:", err.Error()) // TODO: handle
+                               if err == nil {
+                                       nextAction = dlFldrActionNextFile

                                }
 
                                }
 

-                               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)
-                               }
-
-                               // 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.Payload())
-       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
-               }
-               receivedBytes += int(n)
-       }
-}
+                                       if _, err := rwc.Write(append(bs, b...)); err != nil {
+                                               return err
+                                       }

 
 

-// 00 28 // DataSize
-// 00 00 // IsFolder
-// 00 02 // PathItemCount
-//
-// 00 00
-// 09
-// 73 75 62 66 6f 6c 64 65 72 // "subfolder"
-//
-// 00 00
-// 15
-// 73 75 62 66 6f 6c 64 65 72 2d 74 65 73 74 66 69 6c 65 2d 35 6b // "subfolder-testfile-5k"
-func readFolderUpload(buf []byte) folderUpload {
-       dataLen := binary.BigEndian.Uint16(buf[0:2])
-
-       fu := folderUpload{
-               DataSize:      buf[0:2], // Size of this structure (not including data size element itself)
-               IsFolder:      buf[2:4],
-               PathItemCount: buf[4:6],
-               FileNamePath:  buf[6 : dataLen+2],
-       }
+                                       if _, err := io.ReadFull(rwc, fileSize); err != nil {
+                                               return err
+                                       }

 
 

-       return fu
-}
+                                       if err := receiveFile(rwc, file, ioutil.Discard, ioutil.Discard, fileTransfer.bytesSentCounter); err != nil {
+                                               s.Logger.Error(err)
+                                       }

 
 

-type folderUpload struct {
-       DataSize      []byte
-       IsFolder      []byte
-       PathItemCount []byte
-       FileNamePath  []byte
-}
+                                       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
+                                       }

 
 

-func (fu *folderUpload) FormattedPath() string {
-       pathItemLen := binary.BigEndian.Uint16(fu.PathItemCount)
+                                       filePath := filepath.Join(fullPath, fu.FormattedPath())

 
 

-       var pathSegments []string
-       pathData := fu.FileNamePath
+                                       hlFile, err := newFileWrapper(s.FS, filePath, 0)
+                                       if err != nil {
+                                               return err
+                                       }

 
 

-       for i := uint16(0); i < pathItemLen; i++ {
-               segLen := pathData[2]
-               pathSegments = append(pathSegments, string(pathData[3:3+segLen]))
-               pathData = pathData[3+segLen:]
-       }
+                                       rLogger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "fileSize", binary.BigEndian.Uint32(fileSize))

 
 

-       return strings.Join(pathSegments, pathSeparator)
-}
+                                       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
+                                       }
+                               }

 
 

-// 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)
+                               // Tell client to send next fileWrapper
+                               if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
+                                       return err
+                               }
+                       }
+               }
+               rLogger.Infof("Folder upload complete")

        }
        }

-       sort.Sort(byClientID(clients))
-       return clients
+
+       return nil

 }
 }