cmd/cli: fix reset DNS when doing self-uninstall

While at it, also using "ctrld uninstall" on unix platform, ensuring
everything is cleanup properly.

cmd/cli/self_kill_unix.go

@@ -0,0 +1,56 @@
+//go:build unix
+
+package cli
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"syscall"
+
+	"github.com/Control-D-Inc/ctrld/internal/controld"
+	"github.com/rs/zerolog"
+)
+
+func selfUninstall(err error, p *prog, logger zerolog.Logger) {
+	var uer *controld.UtilityErrorResponse
+	if errors.As(err, &uer) && uer.ErrorField.Code == controld.InvalidConfigCode {
+		if runtime.GOOS == "linux" {
+			s, err := newService(p, svcConfig)
+			if err != nil {
+				logger.Warn().Err(err).Msg("failed to create new service")
+			} else {
+				selfUninstallLinux(err, p, logger)
+				_ = s.Stop()
+				os.Exit(0)
+			}
+		}
+
+		bin, err := os.Executable()
+		if err != nil {
+			logger.Fatal().Err(err).Msg("could not determine executable")
+		}
+		args := []string{"uninstall"}
+		if !deactivationPinNotSet() {
+			args = append(args, fmt.Sprintf("--pin=%d", cdDeactivationPin))
+		}
+		cmd := exec.Command(bin, args...)
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		if err := cmd.Start(); err != nil {
+			logger.Fatal().Err(err).Msg("could not start self uninstall command")
+		}
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		logger.Warn().Msgf("service was uninstalled because device %q does not exist", cdUID)
+		_ = cmd.Wait()
+		os.Exit(0)
+	}
+}
+
+func selfUninstallLinux(err error, p *prog, logger zerolog.Logger) {
+	if uninstallIfInvalidCdUID(err, p, logger) {
+		logger.Warn().Msgf("service was uninstalled because device %q does not exist", cdUID)
+	}
+}