]> git.r.bdr.sh - rbdr/mobius/blobdiff - hotline/server.go
Add initial support for resource and info forks
[rbdr/mobius] / hotline / server.go
index 90b7ea019db4bc575b62253634a0e70fc19c6f90..9df89f2b219ac0a7f24e57c48cbc8a6b2a967cb0 100644 (file)
@@ -1,12 +1,17 @@
 package hotline
 
 import (
+       "bufio"
+       "bytes"
        "context"
        "encoding/binary"
        "errors"
        "fmt"
+       "github.com/go-playground/validator/v10"
        "go.uber.org/zap"
+       "gopkg.in/yaml.v3"
        "io"
+       "io/fs"
        "io/ioutil"
        "math/big"
        "math/rand"
@@ -15,26 +20,34 @@ import (
        "path"
        "path/filepath"
        "runtime/debug"
-       "sort"
        "strings"
        "sync"
        "time"
-
-       "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
 )
 
+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
-       FlatNews      []byte
        ThreadedNews  *ThreadedNews
        FileTransfers map[uint32]*FileTransfer
        Config        *Config
@@ -42,19 +55,16 @@ type Server struct {
        Logger        *zap.SugaredLogger
        PrivateChats  map[uint32]*PrivateChat
        NextGuestID   *uint16
-       TrackerPassID []byte
+       TrackerPassID [4]byte
        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
+       mux    sync.Mutex
 
-       mux         sync.Mutex
        flatNewsMux sync.Mutex
+       FlatNews    []byte
 }
 
 type PrivateChat struct {
@@ -63,27 +73,41 @@ type PrivateChat struct {
 }
 
 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)
-       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)
-       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
 }
 
-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 {
@@ -91,7 +115,16 @@ func (s *Server) ServeFileTransfers(ln net.Listener) error {
                }
 
                go func() {
-                       if err := s.handleFileTransfer(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)
                        }
                }()
@@ -130,14 +163,12 @@ func (s *Server) sendTransaction(t Transaction) error {
                "IsReply", t.IsReply,
                "type", handler.Name,
                "sentBytes", n,
-               "remoteAddr", client.Connection.RemoteAddr(),
+               "remoteAddr", client.RemoteAddr,
        )
        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) Serve(ctx context.Context, ln net.Listener) error {
        for {
                conn, err := ln.Accept()
                if err != nil {
@@ -155,7 +186,8 @@ func (s *Server) Serve(ctx context.Context, cancelRoot context.CancelFunc, ln ne
                        }
                }()
                go func() {
-                       if err := s.handleNewConnection(conn); err != nil {
+                       if err := s.handleNewConnection(ctx, conn, conn.RemoteAddr().String()); err != nil {
+                               s.Logger.Infow("New client connection established", "RemoteAddr", conn.RemoteAddr())
                                if err == io.EOF {
                                        s.Logger.Infow("Client disconnected", "RemoteAddr", conn.RemoteAddr())
                                } else {
@@ -171,7 +203,7 @@ const (
 )
 
 // 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),
@@ -185,32 +217,18 @@ func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredL
                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
-       }
-       server.APIListener = ln
-
-       if netPort != 0 {
-               netPort += 1
+               FS:            FS,
        }
 
-       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
-       if _, err := rand.Read(server.TrackerPassID); err != nil {
+       if _, err := rand.Read(server.TrackerPassID[:]); err != nil {
                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(configDir + agreementFile)
+       if err != nil {
                return nil, err
        }
 
@@ -235,21 +253,26 @@ func NewServer(configDir, netInterface string, netPort int, logger *zap.SugaredL
        *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 {
-                               tr := TrackerRegistration{
-                                       Port:        []byte{0x15, 0x7c},
+                               tr := &TrackerRegistration{
                                        UserCount:   server.userCount(),
-                                       PassID:      server.TrackerPassID,
+                                       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 {
-                                       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)
                                        }
+                                       server.Logger.Infow("Sent Tracker registration", "data", tr)
                                }
 
                                time.Sleep(trackerUpdateFrequency * time.Second)
@@ -313,7 +336,7 @@ func (s *Server) writeThreadedNews() error {
        return err
 }
 
-func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
+func (s *Server) NewClientConn(conn net.Conn, remoteAddr string) *ClientConn {
        s.mux.Lock()
        defer s.mux.Unlock()
 
@@ -328,6 +351,7 @@ func (s *Server) NewClientConn(conn net.Conn) *ClientConn {
                AutoReply:  []byte{},
                Transfers:  make(map[int][]*FileTransfer),
                Agreed:     false,
+               RemoteAddr: remoteAddr,
        }
        *s.NextGuestID++
        ID := *s.NextGuestID
@@ -355,7 +379,37 @@ func (s *Server) NewUser(login, name, password string, access []byte) error {
        }
        s.Accounts[login] = &account
 
-       return ioutil.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
+       return s.FS.WriteFile(s.ConfigDir+"Users/"+login+".yaml", out, 0666)
+}
+
+func (s *Server) UpdateUser(login, newLogin, name, password string, access []byte) error {
+       s.mux.Lock()
+       defer s.mux.Unlock()
+
+       // update renames the user login
+       if login != newLogin {
+               err := os.Rename(s.ConfigDir+"Users/"+login+".yaml", 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(s.ConfigDir+"Users/"+newLogin+".yaml", out, 0666); err != nil {
+               return err
+       }
+
+       return nil
 }
 
 // DeleteUser deletes the user account
@@ -365,7 +419,7 @@ func (s *Server) DeleteUser(login string) error {
 
        delete(s.Accounts, login)
 
-       return FS.Remove(s.ConfigDir + "Users/" + login + ".yaml")
+       return s.FS.Remove(s.ConfigDir + "Users/" + login + ".yaml")
 }
 
 func (s *Server) connectedUsers() []Field {
@@ -395,7 +449,6 @@ func (s *Server) loadThreadedNews(threadedNewsPath string) error {
                return err
        }
        decoder := yaml.NewDecoder(fh)
-       decoder.SetStrict(true)
 
        return decoder.Decode(s.ThreadedNews)
 }
@@ -412,14 +465,13 @@ func (s *Server) loadAccounts(userDir string) error {
        }
 
        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)
-               decoder.SetStrict(true)
                if err := decoder.Decode(&account); err != nil {
                        return err
                }
@@ -430,17 +482,22 @@ func (s *Server) loadAccounts(userDir 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)
-       decoder.SetStrict(true)
        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
 }
 
@@ -448,17 +505,25 @@ const (
        minTransactionLen = 22 // minimum length of any transaction
 )
 
-// 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
+// dontPanic recovers and logs panics instead of crashing
+// TODO: remove this after known issues are fixed
+func dontPanic(logger *zap.SugaredLogger) {
+       if r := recover(); r != nil {
+               fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
+               logger.Errorw("PANIC", "err", r, "trace", string(debug.Stack()))
        }
-       if err := Handshake(conn, handshakeBuf[:12]); err != nil {
+}
+
+// handleNewConnection takes a new net.Conn and performs the initial login sequence
+func (s *Server) handleNewConnection(ctx context.Context, conn net.Conn, remoteAddr string) error {
+       defer dontPanic(s.Logger)
+
+       if err := Handshake(conn); err != nil {
                return err
        }
 
        buf := make([]byte, 1024)
+       // TODO: fix potential short read with io.ReadFull
        readLen, err := conn.Read(buf)
        if readLen < minTransactionLen {
                return err
@@ -472,15 +537,8 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
                return err
        }
 
-       c := s.NewClientConn(conn)
+       c := s.NewClientConn(conn, remoteAddr)
        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
@@ -521,7 +579,7 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
                *c.Flags = []byte{0, 2}
        }
 
-       s.Logger.Infow("Client connection received", "login", login, "version", *c.Version, "RemoteAddr", conn.RemoteAddr().String())
+       s.Logger.Infow("Client connection received", "login", login, "version", *c.Version, "RemoteAddr", remoteAddr)
 
        s.outbox <- c.NewReply(clientLogin,
                NewField(fieldVersion, []byte{0x00, 0xbe}),
@@ -535,8 +593,8 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
        // Show agreement to client
        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 {
+       // 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.notifyOthers(
@@ -573,7 +631,7 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
                        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
+               // iterate over all 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)
@@ -583,7 +641,7 @@ func (s *Server) handleNewConnection(conn net.Conn) error {
 }
 
 // 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
+// in the 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)
@@ -614,83 +672,166 @@ const dlFldrActionResumeFile = 2
 const dlFldrActionNextFile = 3
 
 // handleFileTransfer receives a client net.Conn from the file transfer server, performs the requested transfer type, then closes the connection
-func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
-       defer func() {
-               if err := conn.Close(); err != nil {
-                       s.Logger.Errorw("error closing connection", "error", err)
-               }
-       }()
+func (s *Server) handleFileTransfer(ctx context.Context, rwc io.ReadWriter) error {
+       defer dontPanic(s.Logger)
 
        txBuf := make([]byte, 16)
-       _, err := conn.Read(txBuf)
-       if err != nil {
+       if _, err := io.ReadFull(rwc, txBuf); err != nil {
                return err
        }
 
        var t transfer
-       _, err = t.Write(txBuf)
-       if err != nil {
+       if _, err := t.Write(txBuf); err != nil {
                return err
        }
 
        transferRefNum := binary.BigEndian.Uint32(t.ReferenceNumber[:])
-       fileTransfer := s.FileTransfers[transferRefNum]
+       defer func() {
+               s.mux.Lock()
+               delete(s.FileTransfers, transferRefNum)
+               s.mux.Unlock()
+       }()
+
+       s.mux.Lock()
+       fileTransfer, ok := s.FileTransfers[transferRefNum]
+       s.mux.Unlock()
+       if !ok {
+               return errors.New("invalid transaction ID")
+       }
+
+       rLogger := s.Logger.With(
+               "remoteAddr", ctx.Value(contextKeyReq).(requestCtx).remoteAddr,
+               "xferID", transferRefNum,
+       )
 
        switch fileTransfer.Type {
        case FileDownload:
+               s.Stats.DownloadCounter += 1
+
                fullFilePath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
                if err != nil {
                        return err
                }
 
-               ffo, err := NewFlattenedFileObject(
-                       s.Config.FileRoot,
-                       fileTransfer.FilePath,
-                       fileTransfer.FileName,
-               )
+               var dataOffset int64
+               if fileTransfer.fileResumeData != nil {
+                       dataOffset = int64(binary.BigEndian.Uint32(fileTransfer.fileResumeData.ForkInfoList[0].DataSize[:]))
+               }
+
+               fw, err := newFileWrapper(s.FS, fullFilePath, 0)
                if err != nil {
                        return err
                }
 
-               s.Logger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber)
+               rLogger.Infow("File download started", "filePath", fullFilePath, "transactionRef", fileTransfer.ReferenceNumber)
 
-               // Start by sending flat file object to client
-               if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
-                       return err
+               wr := bufio.NewWriterSize(rwc, 1460)
+
+               // 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 := wr.Write(fw.ffo.BinaryMarshal()); err != nil {
+                               return err
+                       }
                }
 
-               file, err := FS.Open(fullFilePath)
+               file, err := fw.dataForkReader()
                if err != nil {
                        return err
                }
 
-               sendBuffer := make([]byte, 1048576)
-               for {
-                       var bytesRead int
-                       if bytesRead, err = file.Read(sendBuffer); err == io.EOF {
-                               break
+               if err := sendFile(wr, file, int(dataOffset)); err != nil {
+                       return err
+               }
+
+               if err := wr.Flush(); err != nil {
+                       return err
+               }
+
+               // if the client requested to resume transfer, do not send the resource fork, or it will be appended into the fileWrapper data
+               if fileTransfer.fileResumeData == nil {
+                       err = binary.Write(wr, binary.BigEndian, fw.rsrcForkHeader())
+                       if err != nil {
+                               return err
                        }
+                       if err := wr.Flush(); err != nil {
+                               return err
+                       }
+               }
+
+               rFile, err := fw.rsrcForkFile()
+               if err != nil {
+                       return nil
+               }
+
+               err = sendFile(wr, rFile, int(dataOffset))
+
+               if err := wr.Flush(); err != nil {
+                       return err
+               }
+
+       case FileUpload:
+               s.Stats.UploadCounter += 1
+
+               destinationFile, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
+               if err != nil {
+                       return err
+               }
 
-                       fileTransfer.BytesSent += bytesRead
+               var file *os.File
 
-                       delete(s.FileTransfers, transferRefNum)
+               // 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
 
-                       if _, err := conn.Write(sendBuffer[:bytesRead]); err != nil {
+               // 1) Check for existing file:
+               _, err = os.Stat(destinationFile)
+               if err == nil {
+                       // If found, that means this upload is intended to replace the file
+                       if err = os.Remove(destinationFile); err != nil {
                                return err
                        }
+                       file, err = os.Create(destinationFile + incompleteFileSuffix)
                }
-       case FileUpload:
-               destinationFile := s.Config.FileRoot + ReadFilePath(fileTransfer.FilePath) + "/" + string(fileTransfer.FileName)
-               newFile, err := FS.Create(destinationFile)
+               if errors.Is(err, fs.ErrNotExist) {
+                       // If not found, open or create a new .incomplete file
+                       file, err = os.OpenFile(destinationFile+incompleteFileSuffix, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
+                       if err != nil {
+                               return err
+                       }
+               }
+
+               f, err := newFileWrapper(s.FS, destinationFile, 0)
                if err != nil {
                        return err
                }
-               defer func() { _ = newFile.Close() }()
+
+               defer func() { _ = file.Close() }()
 
                s.Logger.Infow("File upload started", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
 
-               if err := receiveFile(conn, newFile, nil); err != nil {
-                       s.Logger.Errorw("file upload error", "error", err)
+               rForkWriter := io.Discard
+               iForkWriter := io.Discard
+               if s.Config.PreserveResourceForks {
+                       rForkWriter, err = f.rsrcForkWriter()
+                       if err != nil {
+                               return err
+                       }
+
+                       iForkWriter, err = f.infoForkWriter()
+                       if err != nil {
+                               return err
+                       }
+               }
+
+               if err := receiveFile(rwc, file, rForkWriter, iForkWriter); err != nil {
+                       return err
+               }
+
+               if err := s.FS.Rename(destinationFile+".incomplete", destinationFile); err != nil {
+                       return err
                }
 
                s.Logger.Infow("File upload complete", "transactionRef", fileTransfer.ReferenceNumber, "dstFile", destinationFile)
@@ -698,26 +839,26 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
                // 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:
                //
-               // 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
-               //                      []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:
-               //                      [4]byte - file size
+               //                      [4]byte - fileWrapper size
                //                      []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
@@ -732,16 +873,29 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
                s.Logger.Infow("Start folder download", "path", fullFilePath, "ReferenceNumber", fileTransfer.ReferenceNumber)
 
                nextAction := make([]byte, 2)
-               if _, err := conn.Read(nextAction); err != nil {
+               if _, err := io.ReadFull(rwc, nextAction); err != nil {
                        return err
                }
 
                i := 0
                err = filepath.Walk(fullFilePath+"/", func(path string, info os.FileInfo, err error) error {
+                       s.Stats.DownloadCounter += 1
+                       i += 1
+
                        if err != nil {
                                return err
                        }
-                       i += 1
+
+                       // 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:]
                        s.Logger.Infow("Sending fileheader", "i", i, "path", path, "fullFilePath", fullFilePath, "subPath", subPath, "IsDir", info.IsDir())
 
@@ -751,75 +905,101 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
 
                        fileHeader := NewFileHeader(subPath, info.IsDir())
 
-                       // Send the file header to client
-                       if _, err := conn.Write(fileHeader.Payload()); err != nil {
+                       // 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
-                       if _, err := conn.Read(nextAction); err != nil {
+                       if _, err := io.ReadFull(rwc, nextAction); err != nil {
                                return err
                        }
-                       if nextAction[1] == 3 {
-                               return nil
-                       }
 
                        s.Logger.Infow("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
                        }
 
-                       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",
                                "fileName", info.Name(),
                                "transactionRef", fileTransfer.ReferenceNumber,
-                               "TransferSize", fmt.Sprintf("%x", ffo.TransferSize()),
+                               "TransferSize", fmt.Sprintf("%x", hlFile.ffo.TransferSize(dataOffset)),
                        )
 
                        // 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
                        }
 
                        // Send ffo bytes to client
-                       if _, err := conn.Write(ffo.BinaryMarshal()); err != nil {
+                       if _, err := rwc.Write(hlFile.ffo.BinaryMarshal()); err != nil {
                                s.Logger.Error(err)
                                return err
                        }
 
-                       file, err := FS.Open(path)
+                       file, err := s.FS.Open(path)
                        if err != nil {
                                return err
                        }
 
-                       // Copy N bytes from file to connection
-                       _, err = io.CopyN(conn, file, int64(binary.BigEndian.Uint32(ffo.FlatFileDataForkHeader.DataSize[:])))
+                       // wr := bufio.NewWriterSize(rwc, 1460)
+                       err = sendFile(rwc, file, int(dataOffset))
                        if err != nil {
                                return err
                        }
-                       file.Close()
 
-                       // TODO: optionally send resource fork header and resource fork data
+                       if nextAction[1] != 2 && hlFile.ffo.FlatFileHeader.ForkCount[1] == 3 {
+                               err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
+                               if err != nil {
+                                       return err
+                               }
 
-                       // Read the client's Next Action request
-                       if _, err := conn.Read(nextAction); err != nil {
+                               rFile, err := hlFile.rsrcForkFile()
+                               if err != nil {
+                                       return err
+                               }
+
+                               err = sendFile(rwc, rFile, int(dataOffset))
+                               if 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
                        }
-                       // TODO: switch behavior based on possible next action
 
-                       return err
+                       return nil
                })
 
        case FolderUpload:
@@ -827,6 +1007,7 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
                if err != nil {
                        return err
                }
+
                s.Logger.Infow(
                        "Folder upload started",
                        "transactionRef", fileTransfer.ReferenceNumber,
@@ -836,28 +1017,38 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
                )
 
                // 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(dstPath); os.IsNotExist(err) {
+                       if err := s.FS.Mkdir(dstPath, 0777); err != nil {
+                               return err
                        }
                }
 
                // 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)
-               itemCount := binary.BigEndian.Uint16(fileTransfer.FolderItemCount)
 
-               readBuffer := make([]byte, 1024)
-               for i := uint16(0); i < itemCount; i++ {
-                       _, err := conn.Read(readBuffer)
-                       if 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
                        }
-                       fu := readFolderUpload(readBuffer)
 
                        s.Logger.Infow(
                                "Folder upload continued",
@@ -869,48 +1060,121 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
 
                        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)
+                                               return err
                                        }
                                }
 
                                // 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 {
-                               // 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(dstPath + "/" + fu.FormattedPath())
+                               if err != nil && !errors.Is(err, fs.ErrNotExist) {
                                        return err
                                }
+                               if err == nil {
+                                       nextAction = dlFldrActionNextFile
+                               }
 
-                               if _, err := conn.Read(fileSize); err != nil {
+                               //  Check if we have a partial file already.  If so, send dlFldrAction_ResumeFile to client to resume upload.
+                               incompleteFile, err := os.Stat(dstPath + "/" + fu.FormattedPath() + incompleteFileSuffix)
+                               if err != nil && !errors.Is(err, fs.ErrNotExist) {
                                        return err
                                }
+                               if err == nil {
+                                       nextAction = dlFldrActionResumeFile
+                               }
 
-                               filePath := dstPath + "/" + fu.FormattedPath()
-                               s.Logger.Infow("Starting file transfer", "path", filePath, "fileNum", i+1, "totalFiles", itemCount, "fileSize", binary.BigEndian.Uint32(fileSize))
-
-                               newFile, err := FS.Create(filePath)
-                               if err != nil {
+                               if _, err := rwc.Write([]byte{0, uint8(nextAction)}); err != nil {
                                        return err
                                }
 
-                               if err := receiveFile(conn, newFile, ioutil.Discard); err != nil {
-                                       s.Logger.Error(err)
+                               switch nextAction {
+                               case dlFldrActionNextFile:
+                                       continue
+                               case dlFldrActionResumeFile:
+                                       offset := make([]byte, 4)
+                                       binary.BigEndian.PutUint32(offset, uint32(incompleteFile.Size()))
+
+                                       file, err := os.OpenFile(dstPath+"/"+fu.FormattedPath()+incompleteFileSuffix, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+                                       if err != nil {
+                                               return err
+                                       }
+
+                                       fileResumeData := NewFileResumeData([]ForkInfoList{*NewForkInfoList(offset)})
+
+                                       b, _ := fileResumeData.BinaryMarshal()
+
+                                       bs := make([]byte, 2)
+                                       binary.BigEndian.PutUint16(bs, uint16(len(b)))
+
+                                       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, ioutil.Discard, ioutil.Discard); err != nil {
+                                               s.Logger.Error(err)
+                                       }
+
+                                       err = os.Rename(dstPath+"/"+fu.FormattedPath()+".incomplete", dstPath+"/"+fu.FormattedPath())
+                                       if err != nil {
+                                               return err
+                                       }
+
+                               case dlFldrActionSendFile:
+                                       if _, err := io.ReadFull(rwc, fileSize); err != nil {
+                                               return err
+                                       }
+
+                                       filePath := dstPath + "/" + fu.FormattedPath()
+
+                                       hlFile, err := newFileWrapper(s.FS, filePath, 0)
+                                       if err != nil {
+                                               return err
+                                       }
+
+                                       s.Logger.Infow("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); err != nil {
+                                               return err
+                                       }
+                                       // _ = newFile.Close()
+                                       if err := os.Rename(filePath+".incomplete", filePath); err != nil {
+                                               return err
+                                       }
                                }
-                               _ = newFile.Close()
 
-                               // Tell client to send next file
-                               if _, err := conn.Write([]byte{0, dlFldrActionNextFile}); err != nil {
-                                       s.Logger.Error(err)
+                               // Tell client to send next fileWrapper
+                               if _, err := rwc.Write([]byte{0, dlFldrActionNextFile}); err != nil {
                                        return err
                                }
-
                        }
                }
                s.Logger.Infof("Folder upload complete")
@@ -918,13 +1182,3 @@ func (s *Server) handleFileTransfer(conn io.ReadWriteCloser) error {
 
        return nil
 }
-
-// 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
-}