all: implement router setup for ddwrt

internal/router/ddwrt.go

@@ -0,0 +1,115 @@
+package router
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+const (
+	nvramCtrldKeyPrefix = "ctrld_"
+	nvramCtrldSetupKey  = "ctrld_setup"
+	nvramRCStartupKey   = "rc_startup"
+)
+
+var ddwrtJffs2NotEnabledErr = errors.New(`could not install service without jffs, follow this guide to enable:
+
+https://wiki.dd-wrt.com/wiki/index.php/Journalling_Flash_File_System
+`)
+
+var nvramKeys = map[string]string{
+	"dns_dnsmasq":     "1",                  // Make dnsmasq running but disable DNS ability, ctrld will replace it.
+	"dnsmasq_options": dnsMasqConfigContent, // Configuration of dnsmasq set by ctrld.
+	"dns_crypt":       "0",                  // Disable DNSCrypt.
+}
+
+func setupDDWrt() error {
+	// Already setup.
+	if val, _ := nvram("get", nvramCtrldSetupKey); val == "1" {
+		return nil
+	}
+
+	// Backup current value, store ctrld's configs.
+	for key, value := range nvramKeys {
+		old, err := nvram("get", key)
+		if err != nil {
+			return fmt.Errorf("%s: %w", old, err)
+		}
+		if out, err := nvram("set", nvramCtrldKeyPrefix+key+"="+old); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+		if out, err := nvram("set", key+"="+value); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+	}
+
+	if out, err := nvram("set", nvramCtrldSetupKey+"=1"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Commit.
+	if out, err := nvram("commit"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Restart dnsmasq service.
+	if err := ddwrtRestartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func cleanupDDWrt() error {
+	// Restore old configs.
+	for key := range nvramKeys {
+		ctrldKey := nvramCtrldKeyPrefix + key
+		old, err := nvram("get", ctrldKey)
+		if err != nil {
+			return fmt.Errorf("%s: %w", old, err)
+		}
+		_, _ = nvram("unset", ctrldKey)
+		if out, err := nvram("set", key+"="+old); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+	}
+
+	if out, err := nvram("unset", "ctrld_setup"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Commit.
+	if out, err := nvram("commit"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Restart dnsmasq service.
+	if err := ddwrtRestartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func postInstallDDWrt() error {
+	return nil
+}
+
+func nvram(args ...string) (string, error) {
+	cmd := exec.Command("nvram", args...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return "", fmt.Errorf("%s:%w", stderr.String(), err)
+	}
+	return strings.TrimSpace(stdout.String()), nil
+}
+
+func ddwrtRestartDNSMasq() error {
+	if out, err := exec.Command("restart_dns").CombinedOutput(); err != nil {
+		return fmt.Errorf("restart_dns: %s, %w", string(out), err)
+	}
+	return nil
+}
+
+func ddwrtJff2Enabled() bool {
+	out, _ := nvram("get", "enable_jffs2")
+	return out == "1"
+}