"errors"
"fmt"
"golang.org/x/text/encoding/charmap"
- "gopkg.in/yaml.v3"
+ "golang.org/x/time/rate"
"io"
"log"
"log/slog"
"net"
"os"
- "path/filepath"
"strings"
"sync"
"time"
NetInterface string
Port int
- Config Config
- ConfigDir string
- Logger *slog.Logger
+ rateLimiters map[string]*rate.Limiter
+
+ handlers map[TranType]HandlerFunc
+
+ Config Config
+ Logger *slog.Logger
TrackerPassID [4]byte
outbox chan Transaction
- // TODO
- Agreement []byte
- banner []byte
- // END TODO
+ Agreement io.ReadSeeker
+ Banner []byte
FileTransferMgr FileTransferMgr
ChatMgr ChatManager
MessageBoard io.ReadWriteSeeker
}
-// NewServer constructs a new Server from a config dir
-func NewServer(config Config, configDir, netInterface string, netPort int, logger *slog.Logger, fs FileStore) (*Server, error) {
- server := Server{
- NetInterface: netInterface,
- Port: netPort,
- Config: config,
- ConfigDir: configDir,
- Logger: logger,
- outbox: make(chan Transaction),
- Stats: NewStats(),
- FS: fs,
- ChatMgr: NewMemChatManager(),
- ClientMgr: NewMemClientMgr(),
- FileTransferMgr: NewMemFileTransferMgr(),
- }
+type Option = func(s *Server)
- // generate a new random passID for tracker registration
- _, err := rand.Read(server.TrackerPassID[:])
- if err != nil {
- return nil, err
+func WithConfig(config Config) func(s *Server) {
+ return func(s *Server) {
+ s.Config = config
}
+}
- server.Agreement, err = os.ReadFile(filepath.Join(configDir, agreementFile))
- if err != nil {
- return nil, err
+func WithLogger(logger *slog.Logger) func(s *Server) {
+ return func(s *Server) {
+ s.Logger = logger
}
+}
- server.AccountManager, err = NewYAMLAccountManager(filepath.Join(configDir, "Users/"))
- if err != nil {
- return nil, fmt.Errorf("error loading accounts: %w", err)
+// WithPort optionally overrides the default TCP port.
+func WithPort(port int) func(s *Server) {
+ return func(s *Server) {
+ s.Port = port
}
+}
- // If the FileRoot is an absolute path, use it, otherwise treat as a relative path to the config dir.
- if !filepath.IsAbs(server.Config.FileRoot) {
- server.Config.FileRoot = filepath.Join(configDir, server.Config.FileRoot)
+// WithInterface optionally sets a specific interface to listen on.
+func WithInterface(netInterface string) func(s *Server) {
+ return func(s *Server) {
+ s.NetInterface = netInterface
}
+}
- server.banner, err = os.ReadFile(filepath.Join(server.ConfigDir, server.Config.BannerFile))
- if err != nil {
- return nil, fmt.Errorf("error opening banner: %w", err)
- }
+type ServerConfig struct {
+}
- if server.Config.EnableTrackerRegistration {
- server.Logger.Info(
- "Tracker registration enabled",
- "frequency", fmt.Sprintf("%vs", trackerUpdateFrequency),
- "trackers", server.Config.Trackers,
- )
+func NewServer(options ...Option) (*Server, error) {
+ server := Server{
+ handlers: make(map[TranType]HandlerFunc),
+ outbox: make(chan Transaction),
+ rateLimiters: make(map[string]*rate.Limiter),
+ FS: &OSFileStore{},
+ ChatMgr: NewMemChatManager(),
+ ClientMgr: NewMemClientMgr(),
+ FileTransferMgr: NewMemFileTransferMgr(),
+ Stats: NewStats(),
+ }
- go server.registerWithTrackers()
+ for _, opt := range options {
+ opt(&server)
}
- // Start Client Keepalive go routine
- go server.keepaliveHandler()
+ // generate a new random passID for tracker registration
+ _, err := rand.Read(server.TrackerPassID[:])
+ if err != nil {
+ return nil, err
+ }
return &server, nil
}
}
func (s *Server) ListenAndServe(ctx context.Context) error {
+ go s.registerWithTrackers(ctx)
+ go s.keepaliveHandler(ctx)
+ go s.processOutbox()
+
var wg sync.WaitGroup
wg.Add(1)
)
if err != nil {
- s.Logger.Error("file transfer error", "reason", err)
+ s.Logger.Error("file transfer error", "err", err)
}
}()
}
}
func (s *Server) sendTransaction(t Transaction) error {
- client := s.ClientMgr.Get(t.clientID)
+ client := s.ClientMgr.Get(t.ClientID)
if client == nil {
return nil
_, err := io.Copy(client.Connection, &t)
if err != nil {
- return fmt.Errorf("failed to send transaction to client %v: %v", t.clientID, err)
+ return fmt.Errorf("failed to send transaction to client %v: %v", t.ClientID, err)
}
return nil
}
}
-func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
- go s.processOutbox()
+// perIPRateLimit controls how frequently an IP address can connect before being throttled.
+// 0.5 = 1 connection every 2 seconds
+const perIPRateLimit = rate.Limit(0.5)
+func (s *Server) Serve(ctx context.Context, ln net.Listener) error {
for {
- conn, err := ln.Accept()
- if err != nil {
- s.Logger.Error("error accepting connection", "err", err)
- }
- connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
- remoteAddr: conn.RemoteAddr().String(),
- })
+ select {
+ case <-ctx.Done():
+ s.Logger.Info("Server shutting down")
+ return ctx.Err()
+ default:
+ conn, err := ln.Accept()
+ if err != nil {
+ s.Logger.Error("Error accepting connection", "err", err)
+ continue
+ }
- go func() {
- s.Logger.Info("Connection established", "RemoteAddr", conn.RemoteAddr())
-
- defer conn.Close()
- if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
- if err == io.EOF {
- s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
- } else {
- s.Logger.Error("error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
+ go func() {
+ ipAddr := strings.Split(conn.RemoteAddr().(*net.TCPAddr).String(), ":")[0]
+
+ connCtx := context.WithValue(ctx, contextKeyReq, requestCtx{
+ remoteAddr: conn.RemoteAddr().String(),
+ })
+
+ s.Logger.Info("Connection established", "ip", ipAddr)
+ defer conn.Close()
+
+ // Check if we have an existing rate limit for the IP and create one if we do not.
+ rl, ok := s.rateLimiters[ipAddr]
+ if !ok {
+ rl = rate.NewLimiter(perIPRateLimit, 1)
+ s.rateLimiters[ipAddr] = rl
}
- }
- }()
+
+ // Check if the rate limit is exceeded and close the connection if so.
+ if !rl.Allow() {
+ s.Logger.Info("Rate limit exceeded", "RemoteAddr", conn.RemoteAddr())
+ conn.Close()
+ return
+ }
+
+ if err := s.handleNewConnection(connCtx, conn, conn.RemoteAddr().String()); err != nil {
+ if err == io.EOF {
+ s.Logger.Info("Client disconnected", "RemoteAddr", conn.RemoteAddr())
+ } else {
+ s.Logger.Error("Error serving request", "RemoteAddr", conn.RemoteAddr(), "err", err)
+ }
+ }
+ }()
+ }
}
}
-const (
- agreementFile = "Agreement.txt"
-)
+// time in seconds between tracker re-registration
+const trackerUpdateFrequency = 300
-func (s *Server) registerWithTrackers() {
+// registerWithTrackers runs every trackerUpdateFrequency seconds to update the server's tracker entry on all configured
+// trackers.
+func (s *Server) registerWithTrackers(ctx context.Context) {
for {
- tr := &TrackerRegistration{
- UserCount: len(s.ClientMgr.List()),
- PassID: s.TrackerPassID,
- Name: s.Config.Name,
- Description: s.Config.Description,
- }
- binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
- for _, t := range s.Config.Trackers {
- if err := register(&RealDialer{}, t, tr); err != nil {
- s.Logger.Error(fmt.Sprintf("unable to register with tracker %v", t), "error", err)
+ if s.Config.EnableTrackerRegistration {
+ for _, t := range s.Config.Trackers {
+ tr := &TrackerRegistration{
+ UserCount: len(s.ClientMgr.List()),
+ PassID: s.TrackerPassID,
+ Name: s.Config.Name,
+ Description: s.Config.Description,
+ }
+ binary.BigEndian.PutUint16(tr.Port[:], uint16(s.Port))
+
+ // Check the tracker string for a password. This is janky but avoids a breaking change to the Config
+ // Trackers field.
+ splitAddr := strings.Split(":", t)
+ if len(splitAddr) == 3 {
+ tr.Password = splitAddr[2]
+ }
+
+ if err := register(&RealDialer{}, t, tr); err != nil {
+ s.Logger.Error(fmt.Sprintf("Unable to register with tracker %v", t), "error", err)
+ }
}
}
-
+ // Using time.Ticker with for/select would be more idiomatic, but it's super annoying that it doesn't tick on
+ // first pass. Revist, maybe.
+ // https://github.com/golang/go/issues/17601
time.Sleep(trackerUpdateFrequency * time.Second)
}
}
-// keepaliveHandler
-func (s *Server) keepaliveHandler() {
- for {
- time.Sleep(idleCheckInterval * time.Second)
-
- for _, c := range s.ClientMgr.List() {
- c.mu.Lock()
-
- c.IdleTime += idleCheckInterval
+const (
+ userIdleSeconds = 300 // time in seconds before an inactive user is marked idle
+ idleCheckInterval = 10 // time in seconds to check for idle users
+)
- // Check if the user
- if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
- c.Flags.Set(UserFlagAway, 1)
+// keepaliveHandler runs every idleCheckInterval seconds and increments a user's idle time by idleCheckInterval seconds.
+// If the updated idle time exceeds userIdleSeconds and the user was not previously idle, we notify all connected clients
+// that the user has gone idle. For most clients, this turns the user grey in the user list.
+func (s *Server) keepaliveHandler(ctx context.Context) {
+ ticker := time.NewTicker(idleCheckInterval * time.Second)
+ defer ticker.Stop()
- c.SendAll(
- TranNotifyChangeUser,
- NewField(FieldUserID, c.ID[:]),
- NewField(FieldUserFlags, c.Flags[:]),
- NewField(FieldUserName, c.UserName),
- NewField(FieldUserIconID, c.Icon),
- )
+ for {
+ select {
+ case <-ctx.Done():
+ return
+ case <-ticker.C:
+ for _, c := range s.ClientMgr.List() {
+ c.mu.Lock()
+ c.IdleTime += idleCheckInterval
+
+ // Check if the user
+ if c.IdleTime > userIdleSeconds && !c.Flags.IsSet(UserFlagAway) {
+ c.Flags.Set(UserFlagAway, 1)
+
+ c.SendAll(
+ TranNotifyChangeUser,
+ NewField(FieldUserID, c.ID[:]),
+ NewField(FieldUserFlags, c.Flags[:]),
+ NewField(FieldUserName, c.UserName),
+ NewField(FieldUserIconID, c.Icon),
+ )
+ }
+ c.mu.Unlock()
}
- c.mu.Unlock()
}
}
}
return clientConn
}
-// loadFromYAMLFile loads data from a YAML file into the provided data structure.
-func loadFromYAMLFile(path string, data interface{}) error {
- fh, err := os.Open(path)
- if err != nil {
- return err
- }
- defer fh.Close()
-
- decoder := yaml.NewDecoder(fh)
- return decoder.Decode(data)
-}
-
func sendBanMessage(rwc io.Writer, message string) {
t := NewTransaction(
TranServerMsg,
func (s *Server) handleNewConnection(ctx context.Context, rwc io.ReadWriteCloser, remoteAddr string) error {
defer dontPanic(s.Logger)
+ if err := performHandshake(rwc); err != nil {
+ return fmt.Errorf("perform handshake: %w", err)
+ }
+
// Check if remoteAddr is present in the ban list
ipAddr := strings.Split(remoteAddr, ":")[0]
if isBanned, banUntil := s.BanList.IsBanned(ipAddr); isBanned {
}
}
- if err := performHandshake(rwc); err != nil {
- return fmt.Errorf("error performing handshake: %w", err)
- }
-
// Create a new scanner for parsing incoming bytes into transaction tokens
scanner := bufio.NewScanner(rwc)
scanner.Split(transactionScanner)
login = GuestAccount
}
- c.logger = s.Logger.With("ip", ipAddr, "login", login)
+ c.Logger = s.Logger.With("ip", ipAddr, "login", login)
// If authentication fails, send error reply and close connection
if !c.Authenticate(login, encodedPassword) {
return err
}
- c.logger.Info("Login failed", "clientVersion", fmt.Sprintf("%x", c.Version))
+ c.Logger.Info("Incorrect login")
return nil
}
c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldNoServerAgreement, []byte{1}))
}
} else {
- c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, s.Agreement))
+ _, _ = c.Server.Agreement.Seek(0, 0)
+ data, _ := io.ReadAll(c.Server.Agreement)
+
+ c.Server.outbox <- NewTransaction(TranShowAgreement, c.ID, NewField(FieldData, data))
}
// If the client has provided a username as part of the login, we can infer that it is using the 1.2.3 login
if len(c.UserName) != 0 {
// Add the client username to the logger. For 1.5+ clients, we don't have this information yet as it comes as
// part of TranAgreed
- c.logger = c.logger.With("Name", string(c.UserName))
- c.logger.Info("Login successful", "clientVersion", "Not sent (probably 1.2.3)")
+ c.Logger = c.Logger.With("name", string(c.UserName))
+ c.Logger.Info("Login successful")
// Notify other clients on the server that the new user has logged in. For 1.5+ clients we don't have this
// information yet, so we do it in TranAgreed instead
// Scan for new transactions and handle them as they come in.
for scanner.Scan() {
// Copy the scanner bytes to a new slice to it to avoid a data race when the scanner re-uses the buffer.
- buf := make([]byte, len(scanner.Bytes()))
- copy(buf, scanner.Bytes())
+ tmpBuf := make([]byte, len(scanner.Bytes()))
+ copy(tmpBuf, scanner.Bytes())
var t Transaction
- if _, err := t.Write(buf); err != nil {
+ if _, err := t.Write(tmpBuf); err != nil {
return err
}
"Name", string(fileTransfer.ClientConn.UserName),
)
- fullPath, err := readPath(s.Config.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
+ fullPath, err := ReadPath(fileTransfer.FileRoot, fileTransfer.FilePath, fileTransfer.FileName)
if err != nil {
return err
}
switch fileTransfer.Type {
case BannerDownload:
- if _, err := io.Copy(rwc, bytes.NewBuffer(s.banner)); err != nil {
- return fmt.Errorf("error sending banner: %w", err)
+ if _, err := io.Copy(rwc, bytes.NewBuffer(s.Banner)); err != nil {
+ return fmt.Errorf("banner download: %w", err)
}
case FileDownload:
s.Stats.Increment(StatDownloadCounter, StatDownloadsInProgress)
err = UploadHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
if err != nil {
- return fmt.Errorf("file upload error: %w", err)
+ return fmt.Errorf("file upload: %w", err)
}
case FolderDownload:
err = DownloadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
if err != nil {
- return fmt.Errorf("file upload error: %w", err)
+ return fmt.Errorf("folder download: %w", err)
}
case FolderUpload:
err = UploadFolderHandler(rwc, fullPath, fileTransfer, s.FS, rLogger, s.Config.PreserveResourceForks)
if err != nil {
- return fmt.Errorf("file upload error: %w", err)
+ return fmt.Errorf("folder upload: %w", err)
}
}
return nil
}
+
+func (s *Server) SendAll(t TranType, fields ...Field) {
+ for _, c := range s.ClientMgr.List() {
+ s.outbox <- NewTransaction(t, c.ID, fields...)
+ }
+}
+
+func (s *Server) Shutdown(msg []byte) {
+ s.Logger.Info("Shutdown signal received")
+ s.SendAll(TranDisconnectMsg, NewField(FieldData, msg))
+
+ time.Sleep(3 * time.Second)
+
+ os.Exit(0)
+}
git.r.bdr.sh / rbdr / mobius / blobdiff