Send terminal notification on peer session expiry (#1660)

Send notification through terminal on user session expiration in Linux and macOS, 
unless UI application is installed to handle it instead.

client/internal/peer/status.go

@@ -5,6 +5,9 @@ import (
 	"sync"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	gstatus "google.golang.org/grpc/status"
+
 	"github.com/netbirdio/netbird/client/internal/relay"
 	"github.com/netbirdio/netbird/iface"
 )
@@ -376,6 +379,24 @@ func (d *Status) GetManagementState() ManagementState {
 	}
 }
 
+// IsLoginRequired determines if a peer's login has expired.
+func (d *Status) IsLoginRequired() bool {
+	d.mux.Lock()
+	defer d.mux.Unlock()
+
+	// if peer is connected to the management then login is not expired
+	if d.managementState {
+		return false
+	}
+
+	s, ok := gstatus.FromError(d.managementError)
+	if ok && (s.Code() == codes.InvalidArgument || s.Code() == codes.PermissionDenied) {
+		return true
+
+	}
+	return false
+}
+
 func (d *Status) GetSignalState() SignalState {
 	return SignalState{
 		d.signalAddress,

client/internal/session.go

@@ -0,0 +1,82 @@
+package internal
+
+import (
+	"context"
+	"os/exec"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/netbirdio/netbird/client/internal/peer"
+)
+
+type SessionWatcher struct {
+	ctx   context.Context
+	mutex sync.Mutex
+
+	peerStatusRecorder *peer.Status
+	watchTicker        *time.Ticker
+
+	sendNotification bool
+	onExpireListener func()
+}
+
+// NewSessionWatcher creates a new instance of SessionWatcher.
+func NewSessionWatcher(ctx context.Context, peerStatusRecorder *peer.Status) *SessionWatcher {
+	s := &SessionWatcher{
+		ctx:                ctx,
+		peerStatusRecorder: peerStatusRecorder,
+		watchTicker:        time.NewTicker(2 * time.Second),
+	}
+	go s.startWatcher()
+	return s
+}
+
+// SetOnExpireListener sets the callback func to be called when the session expires.
+func (s *SessionWatcher) SetOnExpireListener(onExpire func()) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	s.onExpireListener = onExpire
+}
+
+// startWatcher continuously checks if the session requires login and
+// calls the onExpireListener if login is required.
+func (s *SessionWatcher) startWatcher() {
+	for {
+		select {
+		case <-s.ctx.Done():
+			s.watchTicker.Stop()
+			return
+		case <-s.watchTicker.C:
+			managementState := s.peerStatusRecorder.GetManagementState()
+			if managementState.Connected {
+				s.sendNotification = true
+			}
+
+			isLoginRequired := s.peerStatusRecorder.IsLoginRequired()
+			if isLoginRequired && s.sendNotification && s.onExpireListener != nil {
+				s.mutex.Lock()
+				s.onExpireListener()
+				s.sendNotification = false
+				s.mutex.Unlock()
+			}
+		}
+	}
+}
+
+// CheckUIApp checks whether UI application is running.
+func CheckUIApp() bool {
+	cmd := exec.Command("ps", "-ef")
+	output, err := cmd.Output()
+	if err != nil {
+		return false
+	}
+
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		if strings.Contains(line, "netbird-ui") && !strings.Contains(line, "grep") {
+			return true
+		}
+	}
+	return false
+}

client/server/server.go

@@ -3,6 +3,8 @@ package server
 import (
 	"context"
 	"fmt"
+	"os/exec"
+	"runtime"
 	"sync"
 	"time"
 
@@ -39,6 +41,7 @@ type Server struct {
 	proto.UnimplementedDaemonServiceServer
 
 	statusRecorder *peer.Status
+	sessionWatcher *internal.SessionWatcher
 
 	mgmProbe    *internal.Probe
 	signalProbe *internal.Probe
@@ -116,6 +119,11 @@ func (s *Server) Start() error {
 	s.statusRecorder.UpdateManagementAddress(config.ManagementURL.String())
 	s.statusRecorder.UpdateRosenpass(config.RosenpassEnabled, config.RosenpassPermissive)
 
+	if s.sessionWatcher == nil {
+		s.sessionWatcher = internal.NewSessionWatcher(s.rootCtx, s.statusRecorder)
+		s.sessionWatcher.SetOnExpireListener(s.onSessionExpire)
+	}
+
 	if !config.DisableAutoConnect {
 		go func() {
 			if err := internal.RunClientWithProbes(ctx, config, s.statusRecorder, s.mgmProbe, s.signalProbe, s.relayProbe, s.wgProbe); err != nil {
@@ -542,6 +550,17 @@ func (s *Server) GetConfig(_ context.Context, _ *proto.GetConfigRequest) (*proto
 	}, nil
 }
 
+func (s *Server) onSessionExpire() {
+	if runtime.GOOS != "windows" {
+		isUIActive := internal.CheckUIApp()
+		if !isUIActive {
+			if err := sendTerminalNotification(); err != nil {
+				log.Errorf("send session expire terminal notification: %v", err)
+			}
+		}
+	}
+}
+
 func toProtoFullStatus(fullStatus peer.FullStatus) *proto.FullStatus {
 	pbFullStatus := proto.FullStatus{
 		ManagementState: &proto.ManagementState{},
@@ -604,3 +623,31 @@ func toProtoFullStatus(fullStatus peer.FullStatus) *proto.FullStatus {
 
 	return &pbFullStatus
 }
+
+// sendTerminalNotification sends a terminal notification message
+// to inform the user that the NetBird connection session has expired.
+func sendTerminalNotification() error {
+	message := "NetBird connection session expired\n\nPlease re-authenticate to connect to the network."
+	echoCmd := exec.Command("echo", message)
+	wallCmd := exec.Command("sudo", "wall")
+
+	echoCmdStdout, err := echoCmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+	wallCmd.Stdin = echoCmdStdout
+
+	if err := echoCmd.Start(); err != nil {
+		return err
+	}
+
+	if err := wallCmd.Start(); err != nil {
+		return err
+	}
+
+	if err := echoCmd.Wait(); err != nil {
+		return err
+	}
+
+	return wallCmd.Wait()
+}