cmd/ctrld: restoring DNS on darwin before stop

Otherwise, we experiment with ctrld slow start after rebooting, because
the network check continuously report failed status even the network
state is up. Restoring the DNS before stopping, we leave the network
state as default, as long as ctrld starts, the DNS is configured again.

cmd/ctrld/prog.go

@@ -138,6 +138,7 @@ func (p *prog) Stop(s service.Service) error {
 		mainLog.Error().Err(err).Msg("de-allocate ip failed")
 		return err
 	}
+	p.preStop()
 	mainLog.Info().Msg("Service stopped")
 	close(p.stopCh)
 	return nil

cmd/ctrld/prog_darwin.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"github.com/kardianos/service"
+)
+
+func (p *prog) preRun() {
+	if !service.Interactive() {
+		p.setDNS()
+	}
+}
+
+func setDependencies(svc *service.Config) {}
+
+func setWorkingDirectory(svc *service.Config, dir string) {
+	svc.WorkingDirectory = dir
+}
+
+func (p *prog) preStop() {
+	if !service.Interactive() {
+		p.resetDNS()
+	}
+}

cmd/ctrld/prog_freebsd.go

@@ -18,3 +18,5 @@ func setDependencies(svc *service.Config) {
 }
 
 func setWorkingDirectory(svc *service.Config, dir string) {}
+
+func (p *prog) preStop() {}

cmd/ctrld/prog_linux.go

@@ -22,3 +22,5 @@ func setDependencies(svc *service.Config) {
 func setWorkingDirectory(svc *service.Config, dir string) {
 	svc.WorkingDirectory = dir
 }
+
+func (p *prog) preStop() {}

cmd/ctrld/prog_others.go

@@ -1,4 +1,4 @@
-//go:build !linux && !freebsd
+//go:build !linux && !freebsd && !darwin
 
 package main
 
@@ -12,3 +12,5 @@ func setWorkingDirectory(svc *service.Config, dir string) {
 	// WorkingDirectory is not supported on Windows.
 	svc.WorkingDirectory = dir
 }
+
+func (p *prog) preStop() {}