all: refactor router code to use interface

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

internal/router/pfsense/pfsense.go

@@ -0,0 +1,91 @@
+package pfsense
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/kardianos/service"
+)
+
+const (
+	Name = "pfsens"
+
+	rcPath        = "/usr/local/etc/rc.d"
+	unboundRcPath = rcPath + "/unbound"
+	dnsmasqRcPath = rcPath + "/dnsmasq"
+)
+
+const pfsenseInitScript = `#!/bin/sh
+
+# PROVIDE: {{.Name}}
+# REQUIRE: SERVERS
+# REQUIRE: unbound dnsmasq securelevel
+# KEYWORD: shutdown
+
+. /etc/rc.subr
+
+name="{{.Name}}"
+{{.Name}}_env="IS_DAEMON=1"
+pidfile="/var/run/${name}.pid"
+command="/usr/sbin/daemon"
+daemon_args="-P ${pidfile} -r -t \"${name}: daemon\"{{if .WorkingDirectory}} -c {{.WorkingDirectory}}{{end}}"
+command_args="${daemon_args} {{.Path}}{{range .Arguments}} {{.}}{{end}}"
+
+run_rc_command "$1"
+`
+
+type Pfsense struct {
+	cfg     *ctrld.Config
+	svcName string
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on Pfsense routers.
+func New(cfg *ctrld.Config) *Pfsense {
+	return &Pfsense{cfg: cfg}
+}
+
+func (p *Pfsense) ConfigureService(svc *service.Config) error {
+	svc.Option["SysvScript"] = pfsenseInitScript
+	p.svcName = svc.Name
+	return nil
+}
+
+func (p *Pfsense) Install(config *service.Config) error {
+	return nil
+}
+
+func (p *Pfsense) Uninstall(config *service.Config) error {
+	return nil
+}
+
+func (p *Pfsense) PreRun() error {
+	return nil
+}
+
+func (p *Pfsense) Configure() error {
+	p.cfg.Listener["0"].IP = "127.0.0.1"
+	p.cfg.Listener["0"].Port = 53
+	return nil
+}
+
+func (p *Pfsense) Setup() error {
+	// If Pfsense is in DNS Resolver mode, ensure no unbound processes running.
+	_ = exec.Command("killall", "unbound").Run()
+
+	// If Pfsense is in DNS Forwarder mode, ensure no dnsmasq processes running.
+	_ = exec.Command("killall", "dnsmasq").Run()
+	return nil
+}
+
+func (p *Pfsense) Cleanup() error {
+	if err := os.Remove(filepath.Join(rcPath, p.svcName+".sh")); err != nil {
+		return fmt.Errorf("os.Remove: %w", err)
+	}
+	_ = exec.Command(unboundRcPath, "onerestart").Run()
+	_ = exec.Command(dnsmasqRcPath, "onerestart").Run()
+
+	return nil
+}