Fix a race condition where a concurrent user-issued Up or Down command (#5418)

could interleave with a sleep/wake event causing out-of-order state
transitions. The mutex now covers the full duration of each handler
including the status check, the Up/Down call, and the flag update.

Note: if Up or Down commands are triggered in parallel with sleep/wake
events, the overall ordering of up/down/sleep/wake operations is still
not guaranteed beyond what the mutex provides within the handler itself.

client/server/sleep.go

@@ -0,0 +1,46 @@
+package server
+
+import (
+	"context"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/internal"
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+// serverAgent adapts Server to the handler.Agent and handler.StatusChecker interfaces
+type serverAgent struct {
+	s *Server
+}
+
+func (a *serverAgent) Up(ctx context.Context) error {
+	_, err := a.s.Up(ctx, &proto.UpRequest{})
+	return err
+}
+
+func (a *serverAgent) Down(ctx context.Context) error {
+	_, err := a.s.Down(ctx, &proto.DownRequest{})
+	return err
+}
+
+func (a *serverAgent) Status() (internal.StatusType, error) {
+	return internal.CtxGetState(a.s.rootCtx).Status()
+}
+
+// NotifyOSLifecycle handles operating system lifecycle events by executing appropriate logic based on the request type.
+func (s *Server) NotifyOSLifecycle(callerCtx context.Context, req *proto.OSLifecycleRequest) (*proto.OSLifecycleResponse, error) {
+	switch req.GetType() {
+	case proto.OSLifecycleRequest_WAKEUP:
+		if err := s.sleepHandler.HandleWakeUp(callerCtx); err != nil {
+			return &proto.OSLifecycleResponse{}, err
+		}
+	case proto.OSLifecycleRequest_SLEEP:
+		if err := s.sleepHandler.HandleSleep(callerCtx); err != nil {
+			return &proto.OSLifecycleResponse{}, err
+		}
+	default:
+		log.Errorf("unknown OSLifecycleRequest type: %v", req.GetType())
+	}
+	return &proto.OSLifecycleResponse{}, nil
+}