cmd/cli: ensure all ifaces operation is set correctly

Since ctrld process does not rely on the global variable iface anymore
during runtime, ctrld client's operations must be updated to reflect
this change, too.

cmd/cli/cli.go

@@ -1723,20 +1723,22 @@ func upgradeUrl(baseUrl string) string {
 }
 
 // runningIface returns the value of the iface variable used by ctrld process which is running.
-func runningIface(s service.Service) string {
+func runningIface(s service.Service) *ifaceResponse {
 	if sockDir, err := socketDir(); err == nil {
 		if cc := newSocketControlClient(context.TODO(), s, sockDir); cc != nil {
 			resp, err := cc.post(ifacePath, nil)
 			if err != nil {
-				return ""
+				return nil
 			}
 			defer resp.Body.Close()
-			if buf, _ := io.ReadAll(resp.Body); len(buf) > 0 {
-				return string(buf)
+			res := &ifaceResponse{}
+			if err := json.NewDecoder(resp.Body).Decode(res); err != nil {
+				return nil
 			}
+			return res
 		}
 	}
-	return ""
+	return nil
 }
 
 // resetDnsNoLog performs resetting DNS with logging disable.
@@ -1754,7 +1756,7 @@ func resetDnsNoLog(p *prog) {
 }
 
 // resetDnsTask returns a task which perform reset DNS operation.
-func resetDnsTask(p *prog, s service.Service, isCtrldInstalled bool, currentRunningIface string) task {
+func resetDnsTask(p *prog, s service.Service, isCtrldInstalled bool, ir *ifaceResponse) task {
 	return task{func() error {
 		if iface == "" {
 			return nil
@@ -1764,8 +1766,10 @@ func resetDnsTask(p *prog, s service.Service, isCtrldInstalled bool, currentRunn
 		// process to reset what setDNS has done properly.
 		oldIface := iface
 		iface = "auto"
-		if currentRunningIface != "" {
-			iface = currentRunningIface
+		p.requiredMultiNICsConfig = requiredMultiNICsConfig()
+		if ir != nil {
+			iface = ir.Name
+			p.requiredMultiNICsConfig = ir.All
 		}
 		p.runningIface = iface
 		if isCtrldInstalled {

cmd/cli/commands.go

@@ -197,7 +197,7 @@ NOTE: running "ctrld start" without any arguments will start already installed c
 			isCtrldInstalled := !errors.Is(err, service.ErrNotInstalled)
 
 			// Get current running iface, if any.
-			var currentIface string
+			var currentIface *ifaceResponse
 
 			// If pin code was set, do not allow running start command.
 			if isCtrldRunning {
@@ -522,9 +522,10 @@ func initStopCmd() *cobra.Command {
 				mainLog.Load().Error().Msg(err.Error())
 				return
 			}
-			p.runningIface = iface
-			if ri := runningIface(s); ri != "" {
-				p.runningIface = ri
+			p.preRun()
+			if ir := runningIface(s); ir != nil {
+				p.runningIface = ir.Name
+				p.requiredMultiNICsConfig = ir.All
 			}
 
 			initLogging()
@@ -610,7 +611,9 @@ func initRestartCmd() *cobra.Command {
 				doValidateCdRemoteConfig(cdUID)
 			}
 
-			iface = runningIface(s)
+			if ir := runningIface(s); ir != nil {
+				iface = ir.Name
+			}
 			tasks := []task{
 				{s.Stop, false},
 				{s.Start, true},
@@ -777,9 +780,10 @@ NOTE: Uninstalling will set DNS to values provided by DHCP.`,
 			if iface == "" {
 				iface = "auto"
 			}
-			p.runningIface = iface
-			if ri := runningIface(s); ri != "" {
-				p.runningIface = ri
+			p.preRun()
+			if ir := runningIface(s); ir != nil {
+				p.runningIface = ir.Name
+				p.requiredMultiNICsConfig = ir.All
 			}
 			if err := checkDeactivationPin(s, nil); isCheckDeactivationPinErr(err) {
 				os.Exit(deactivationPinInvalidExitCode)

cmd/cli/control_server.go

@@ -31,6 +31,11 @@ const (
 	sendLogsPath     = "/logs/send"
 )
 
+type ifaceResponse struct {
+	Name string `json:"name"`
+	All  bool   `json:"all"`
+}
+
 type controlServer struct {
 	server *http.Server
 	mux    *http.ServeMux
@@ -205,15 +210,20 @@ func (p *prog) registerControlServerHandler() {
 		w.WriteHeader(http.StatusBadRequest)
 	}))
 	p.cs.register(ifacePath, http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
+		res := &ifaceResponse{Name: iface}
 		// p.setDNS is only called when running as a service
 		if !service.Interactive() {
 			<-p.csSetDnsDone
 			if p.csSetDnsOk {
-				w.Write([]byte(iface))
-				return
+				res.Name = p.runningIface
+				res.All = p.requiredMultiNICsConfig
 			}
 		}
-		w.WriteHeader(http.StatusBadRequest)
+		if err := json.NewEncoder(w).Encode(res); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			http.Error(w, fmt.Sprintf("could not marshal iface data: %v", err), http.StatusInternalServerError)
+			return
+		}
 	}))
 	p.cs.register(viewLogsPath, http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
 		lr, err := p.logReader()