Add packet capture to debug bundle and CLI

client/server/capture.go

@@ -0,0 +1,325 @@
+package server
+
+import (
+	"context"
+	"io"
+	"os"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/client/internal"
+	"github.com/netbirdio/netbird/client/proto"
+	"github.com/netbirdio/netbird/util/capture"
+)
+
+const maxBundleCaptureDuration = 10 * time.Minute
+
+// bundleCapture holds the state of an in-progress capture destined for the
+// debug bundle. The lifecycle is:
+//
+//	StartBundleCapture → capture running, writing to temp file
+//	StopBundleCapture  → capture stopped, temp file available
+//	DebugBundle        → temp file included in zip, then cleaned up
+type bundleCapture struct {
+	mu      sync.Mutex
+	sess    *capture.Session
+	file    *os.File
+	engine  *internal.Engine
+	cancel  context.CancelFunc
+	stopped bool
+}
+
+// stop halts the capture session and closes the pcap writer. Idempotent.
+func (bc *bundleCapture) stop() {
+	bc.mu.Lock()
+	defer bc.mu.Unlock()
+
+	if bc.stopped {
+		return
+	}
+	bc.stopped = true
+
+	if bc.cancel != nil {
+		bc.cancel()
+	}
+	if bc.engine != nil {
+		if err := bc.engine.SetCapture(nil); err != nil {
+			log.Debugf("clear bundle capture: %v", err)
+		}
+	}
+	if bc.sess != nil {
+		bc.sess.Stop()
+	}
+}
+
+// path returns the temp file path, or "" if no file exists.
+func (bc *bundleCapture) path() string {
+	if bc.file == nil {
+		return ""
+	}
+	return bc.file.Name()
+}
+
+// cleanup removes the temp file.
+func (bc *bundleCapture) cleanup() {
+	if bc.file == nil {
+		return
+	}
+	name := bc.file.Name()
+	if err := bc.file.Close(); err != nil {
+		log.Debugf("close bundle capture file: %v", err)
+	}
+	if err := os.Remove(name); err != nil && !os.IsNotExist(err) {
+		log.Debugf("remove bundle capture file: %v", err)
+	}
+	bc.file = nil
+}
+
+// StartCapture streams a pcap or text packet capture over gRPC.
+// Gated by the --enable-capture service flag.
+func (s *Server) StartCapture(req *proto.StartCaptureRequest, stream proto.DaemonService_StartCaptureServer) error {
+	if !s.captureEnabled {
+		return status.Error(codes.PermissionDenied,
+			"packet capture is disabled; reinstall or reconfigure the service with --enable-capture")
+	}
+
+	engine, err := s.getCaptureEngine()
+	if err != nil {
+		return err
+	}
+
+	matcher, err := parseCaptureFilter(req)
+	if err != nil {
+		return status.Errorf(codes.InvalidArgument, "invalid filter: %v", err)
+	}
+
+	pr, pw := io.Pipe()
+
+	opts := capture.Options{
+		Matcher: matcher,
+		SnapLen: req.GetSnapLen(),
+		Verbose: req.GetVerbose(),
+		ASCII:   req.GetAscii(),
+	}
+	if req.GetTextOutput() {
+		opts.TextOutput = pw
+	} else {
+		opts.Output = pw
+	}
+
+	sess, err := capture.NewSession(opts)
+	if err != nil {
+		pw.Close()
+		return status.Errorf(codes.Internal, "create capture session: %v", err)
+	}
+
+	if err := engine.SetCapture(sess); err != nil {
+		sess.Stop()
+		pw.Close()
+		return status.Errorf(codes.Internal, "set capture: %v", err)
+	}
+
+	// Send an empty initial message to signal that the capture was accepted.
+	// The client waits for this before printing the banner, so it must arrive
+	// before any packet data.
+	if err := stream.Send(&proto.CapturePacket{}); err != nil {
+		if clearErr := engine.SetCapture(nil); clearErr != nil {
+			log.Debugf("clear capture after send failure: %v", clearErr)
+		}
+		sess.Stop()
+		pw.Close()
+		return status.Errorf(codes.Internal, "send initial message: %v", err)
+	}
+
+	ctx := stream.Context()
+	if d := req.GetDuration(); d != nil {
+		dur := d.AsDuration()
+		if dur < 0 {
+			if clearErr := engine.SetCapture(nil); clearErr != nil {
+				log.Debugf("clear capture: %v", clearErr)
+			}
+			sess.Stop()
+			pw.Close()
+			return status.Errorf(codes.InvalidArgument, "duration must not be negative")
+		}
+		if dur > 0 {
+			var cancel context.CancelFunc
+			ctx, cancel = context.WithTimeout(ctx, dur)
+			defer cancel()
+		}
+	}
+
+	go func() {
+		<-ctx.Done()
+		if err := engine.SetCapture(nil); err != nil {
+			log.Debugf("clear capture: %v", err)
+		}
+		sess.Stop()
+		pw.Close()
+	}()
+	defer pr.Close()
+
+	log.Infof("packet capture started (text=%v, expr=%q)", req.GetTextOutput(), req.GetFilterExpr())
+	defer func() {
+		stats := sess.Stats()
+		log.Infof("packet capture stopped: %d packets, %d bytes, %d dropped",
+			stats.Packets, stats.Bytes, stats.Dropped)
+	}()
+
+	return streamToGRPC(pr, stream)
+}
+
+func streamToGRPC(r io.Reader, stream proto.DaemonService_StartCaptureServer) error {
+	buf := make([]byte, 32*1024)
+	for {
+		n, readErr := r.Read(buf)
+		if n > 0 {
+			if err := stream.Send(&proto.CapturePacket{Data: buf[:n]}); err != nil {
+				log.Debugf("capture stream send: %v", err)
+				return nil //nolint:nilerr // client disconnected
+			}
+		}
+		if readErr != nil {
+			return nil //nolint:nilerr // pipe closed, capture stopped normally
+		}
+	}
+}
+
+// StartBundleCapture begins capturing packets to a server-side temp file for
+// inclusion in the next debug bundle. Not gated by --enable-capture since the
+// output stays on the server (same trust level as CPU profiling).
+//
+// A timeout auto-stops the capture as a safety net if StopBundleCapture is
+// never called (e.g. CLI crash).
+func (s *Server) StartBundleCapture(_ context.Context, req *proto.StartBundleCaptureRequest) (*proto.StartBundleCaptureResponse, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	s.stopBundleCaptureLocked()
+	s.cleanupBundleCapture()
+
+	engine, err := s.getCaptureEngineLocked()
+	if err != nil {
+		// Not fatal: kernel mode or not connected. Log and return success
+		// so the debug bundle still generates without capture data.
+		log.Warnf("packet capture unavailable, skipping: %v", err)
+		return &proto.StartBundleCaptureResponse{}, nil
+	}
+
+	timeout := req.GetTimeout().AsDuration()
+	if timeout <= 0 || timeout > maxBundleCaptureDuration {
+		timeout = maxBundleCaptureDuration
+	}
+
+	f, err := os.CreateTemp("", "netbird.capture.*.pcap")
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "create temp file: %v", err)
+	}
+
+	sess, err := capture.NewSession(capture.Options{Output: f})
+	if err != nil {
+		f.Close()
+		os.Remove(f.Name())
+		return nil, status.Errorf(codes.Internal, "create capture session: %v", err)
+	}
+
+	if err := engine.SetCapture(sess); err != nil {
+		sess.Stop()
+		f.Close()
+		os.Remove(f.Name())
+		log.Warnf("packet capture unavailable (no filtered device), skipping: %v", err)
+		return &proto.StartBundleCaptureResponse{}, nil
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	bc := &bundleCapture{
+		sess:   sess,
+		file:   f,
+		engine: engine,
+		cancel: cancel,
+	}
+
+	go func() {
+		<-ctx.Done()
+		bc.stop()
+		log.Infof("bundle capture auto-stopped after timeout")
+	}()
+
+	s.bundleCapture = bc
+	log.Infof("bundle capture started (timeout=%s, file=%s)", timeout, f.Name())
+
+	return &proto.StartBundleCaptureResponse{}, nil
+}
+
+// StopBundleCapture stops the running bundle capture. Idempotent.
+func (s *Server) StopBundleCapture(_ context.Context, _ *proto.StopBundleCaptureRequest) (*proto.StopBundleCaptureResponse, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	s.stopBundleCaptureLocked()
+	return &proto.StopBundleCaptureResponse{}, nil
+}
+
+// stopBundleCaptureLocked stops the bundle capture if running. Must hold s.mutex.
+func (s *Server) stopBundleCaptureLocked() {
+	if s.bundleCapture == nil {
+		return
+	}
+	s.bundleCapture.stop()
+
+	stats := s.bundleCapture.sess.Stats()
+	log.Infof("bundle capture stopped: %d packets, %d bytes, %d dropped",
+		stats.Packets, stats.Bytes, stats.Dropped)
+}
+
+// bundleCapturePath returns the temp file path if a capture has been taken,
+// stops any running capture, and returns "". Called from DebugBundle.
+// Must hold s.mutex.
+func (s *Server) bundleCapturePath() string {
+	if s.bundleCapture == nil {
+		return ""
+	}
+
+	s.bundleCapture.stop()
+	return s.bundleCapture.path()
+}
+
+// cleanupBundleCapture removes the temp file and clears state. Must hold s.mutex.
+func (s *Server) cleanupBundleCapture() {
+	if s.bundleCapture == nil {
+		return
+	}
+	s.bundleCapture.cleanup()
+	s.bundleCapture = nil
+}
+
+func (s *Server) getCaptureEngine() (*internal.Engine, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	return s.getCaptureEngineLocked()
+}
+
+func (s *Server) getCaptureEngineLocked() (*internal.Engine, error) {
+	if s.connectClient == nil {
+		return nil, status.Error(codes.FailedPrecondition, "client not connected")
+	}
+	engine := s.connectClient.Engine()
+	if engine == nil {
+		return nil, status.Error(codes.FailedPrecondition, "engine not initialized")
+	}
+	return engine, nil
+}
+
+// parseCaptureFilter returns a Matcher from the request.
+// Returns nil (match all) when no filter expression is set.
+func parseCaptureFilter(req *proto.StartCaptureRequest) (capture.Matcher, error) {
+	expr := req.GetFilterExpr()
+	if expr == "" {
+		return nil, nil //nolint:nilnil // nil Matcher means "match all"
+	}
+	return capture.ParseFilter(expr)
+}

client/server/debug.go

@@ -43,7 +43,9 @@ func (s *Server) DebugBundle(_ context.Context, req *proto.DebugBundleRequest) (
 		}()
 	}
 
-	// Prepare refresh callback for health probes
+	capturePath := s.bundleCapturePath()
+	defer s.cleanupBundleCapture()
+
 	var refreshStatus func()
 	if s.connectClient != nil {
 		engine := s.connectClient.Engine()
@@ -62,6 +64,7 @@ func (s *Server) DebugBundle(_ context.Context, req *proto.DebugBundleRequest) (
 			SyncResponse:   syncResponse,
 			LogPath:        s.logFile,
 			CPUProfile:     cpuProfileData,
+			CapturePath:    capturePath,
 			RefreshStatus:  refreshStatus,
 			ClientMetrics:  clientMetrics,
 		},

client/server/server.go

@@ -88,6 +88,8 @@ type Server struct {
 	profileManager         *profilemanager.ServiceManager
 	profilesDisabled       bool
 	updateSettingsDisabled bool
+	captureEnabled         bool
+	bundleCapture          *bundleCapture
 
 	sleepHandler *sleephandler.SleepHandler
 
@@ -104,7 +106,7 @@ type oauthAuthFlow struct {
 }
 
 // New server instance constructor.
-func New(ctx context.Context, logFile string, configFile string, profilesDisabled bool, updateSettingsDisabled bool) *Server {
+func New(ctx context.Context, logFile string, configFile string, profilesDisabled bool, updateSettingsDisabled bool, captureEnabled bool) *Server {
 	s := &Server{
 		rootCtx:                ctx,
 		logFile:                logFile,
@@ -113,6 +115,7 @@ func New(ctx context.Context, logFile string, configFile string, profilesDisable
 		profileManager:         profilemanager.NewServiceManager(configFile),
 		profilesDisabled:       profilesDisabled,
 		updateSettingsDisabled: updateSettingsDisabled,
+		captureEnabled:         captureEnabled,
 		jwtCache:               newJWTCache(),
 	}
 	agent := &serverAgent{s}

client/server/server_test.go

@@ -103,7 +103,7 @@ func TestConnectWithRetryRuns(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "debug", "", false, false)
+	s := New(ctx, "debug", "", false, false, false)
 
 	s.config = config
 
@@ -164,7 +164,7 @@ func TestServer_Up(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 	err = s.Start()
 	require.NoError(t, err)
 
@@ -234,7 +234,7 @@ func TestServer_SubcribeEvents(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 
 	err = s.Start()
 	require.NoError(t, err)

client/server/setconfig_test.go

@@ -53,7 +53,7 @@ func TestSetConfig_AllFieldsSaved(t *testing.T) {
 	require.NoError(t, err)
 
 	ctx := context.Background()
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 
 	rosenpassEnabled := true
 	rosenpassPermissive := true