all: refactor router code to use interface

So the code is more modular, easier to read/maintain.

internal/router/ubios/ubios.go

@@ -0,0 +1,96 @@
+package ubios
+
+import (
+	"bytes"
+	"os"
+	"strconv"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router/edgeos"
+	"github.com/kardianos/service"
+)
+
+const (
+	Name                   = "ubios"
+	ubiosDNSMasqConfigPath = "/run/dnsmasq.conf.d/zzzctrld.conf"
+)
+
+type Ubios struct {
+	cfg *ctrld.Config
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on Ubios routers.
+func New(cfg *ctrld.Config) *Ubios {
+	return &Ubios{cfg: cfg}
+}
+
+func (u *Ubios) ConfigureService(config *service.Config) error {
+	return nil
+}
+
+func (u *Ubios) Install(config *service.Config) error {
+	// See comment in (*edgeos.EdgeOS).Install method.
+	if edgeos.ContentFilteringEnabled() {
+		return edgeos.ErrContentFilteringEnabled
+	}
+	return nil
+}
+
+func (u *Ubios) Uninstall(_ *service.Config) error {
+	return nil
+}
+
+func (u *Ubios) PreRun() error {
+	return nil
+}
+
+func (u *Ubios) Configure() error {
+	u.cfg.Listener["0"].IP = "127.0.0.1"
+	u.cfg.Listener["0"].Port = 5354
+	return nil
+}
+
+func (u *Ubios) Setup() error {
+	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, u.cfg)
+	if err != nil {
+		return err
+	}
+	if err := os.WriteFile(ubiosDNSMasqConfigPath, []byte(data), 0600); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (u *Ubios) Cleanup() error {
+	// Remove the custom dnsmasq config
+	if err := os.Remove(ubiosDNSMasqConfigPath); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func restartDNSMasq() error {
+	buf, err := os.ReadFile("/run/dnsmasq.pid")
+	if err != nil {
+		return err
+	}
+	pid, err := strconv.ParseUint(string(bytes.TrimSpace(buf)), 10, 64)
+	if err != nil {
+		return err
+	}
+	proc, err := os.FindProcess(int(pid))
+	if err != nil {
+		return err
+	}
+	return proc.Kill()
+}