feat: add DNS management to Network settings

- Add DNS configuration APIs for manual and DHCP modes, including persistence and udhcpc hook support.
- Add a Network settings tab with DNS controls, move Wi-Fi and HTTPS settings into it, and update translations.
- Update locales

server/proto/network.go

@@ -28,3 +28,25 @@ type ConnectWifiReq struct {
 	Ssid     string `validate:"required"`
 	Password string `valid:"required"`
 }
+
+type GetDNSRsp struct {
+	Mode      string   `json:"mode"`
+	Servers   []string `json:"servers"`
+	Effective []string `json:"effective"`
+	DHCP      []string `json:"dhcp"`
+	Info      DNSInfo  `json:"info"`
+}
+
+type SetDNSReq struct {
+	Mode    string   `json:"mode" validate:"required,oneof=manual dhcp"`
+	Servers []string `json:"servers"`
+}
+
+type DNSInfo struct {
+	Interface     string   `json:"interface"`
+	Type          string   `json:"type"`
+	Address       string   `json:"address"`
+	SubnetMask    string   `json:"subnetMask"`
+	Gateway       string   `json:"gateway"`
+	SearchDomains []string `json:"searchDomains"`
+}

server/router/network.go

@@ -10,8 +10,8 @@ import (
 func networkRouter(r *gin.Engine) {
 	service := network.NewService()
 
-	r.POST("/api/network/wifi", service.ConnectWifiNoAuth)        // connect Wi-Fi without auth (only available in ap mode)
-	r.POST("/api/network/wifi/verify", service.VerifyApLogin)     // verify ap login
+	r.POST("/api/network/wifi", service.ConnectWifiNoAuth)    // connect Wi-Fi without auth (only available in ap mode)
+	r.POST("/api/network/wifi/verify", service.VerifyApLogin) // verify ap login
 
 	api := r.Group("/api").Use(middleware.CheckToken())
 
@@ -23,4 +23,7 @@ func networkRouter(r *gin.Engine) {
 	api.GET("/network/wifi", service.GetWifi)                    // get Wi-Fi information
 	api.POST("/network/wifi/connect", service.ConnectWifi)       // connect Wi-Fi
 	api.POST("/network/wifi/disconnect", service.DisconnectWifi) // disconnect Wi-Fi
+
+	api.GET("/network/dns", service.GetDNS)  // get DNS configuration
+	api.POST("/network/dns", service.SetDNS) // set DNS configuration
 }

server/service/network/dns.go

@@ -0,0 +1,614 @@
+package network
+
+import (
+	"bufio"
+	_ "embed"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"NanoKVM-Server/proto"
+
+	"github.com/gin-gonic/gin"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	dnsModeManual = "manual"
+	dnsModeDHCP   = "dhcp"
+
+	dnsConfigDir     = "/etc/kvm/network"
+	dnsModeFile      = "/etc/kvm/network/dns.mode"
+	dnsServersFile   = "/etc/kvm/network/dns.servers"
+	bootResolvFile   = "/boot/resolv.conf"
+	bootResolvBackup = "/boot/resolv.conf.manual.bak"
+	etcResolvFile    = "/etc/resolv.conf"
+	dhcpResolvFile   = "/etc/resolv.conf.dhcp"
+	udhcpcHookFile   = "/usr/share/udhcpc/default.script.d/99-nanokvm-dns"
+
+	maxDNSServers = 6
+)
+
+//go:embed scripts/99-nanokvm-dns
+var udhcpcDNSHook string
+
+type resolvConfig struct {
+	Servers       []string
+	SearchDomains []string
+}
+
+func (s *Service) GetDNS(c *gin.Context) {
+	var rsp proto.Response
+
+	mode := currentDNSMode()
+
+	servers := readManualDNSServers()
+	if len(servers) == 0 {
+		servers, _ = parseResolvConf(bootResolvFile)
+	}
+	if len(servers) == 0 {
+		servers, _ = parseResolvConf(bootResolvBackup)
+	}
+
+	effective, _ := parseResolvConf(etcResolvFile)
+	dhcpConfig, _ := readDHCPResolvConfig(mode == dnsModeDHCP)
+	dhcp := dhcpConfig.Servers
+	info := getDNSInfo()
+
+	rsp.OkRspWithData(c, &proto.GetDNSRsp{
+		Mode:      mode,
+		Servers:   servers,
+		Effective: effective,
+		DHCP:      dhcp,
+		Info:      info,
+	})
+	log.Debugf("get dns config: mode=%s servers=%v effective=%v dhcp=%v info=%+v", mode, servers, effective, dhcp, info)
+}
+
+func (s *Service) SetDNS(c *gin.Context) {
+	var req proto.SetDNSReq
+	var rsp proto.Response
+
+	if err := proto.ParseFormRequest(c, &req); err != nil {
+		rsp.ErrRsp(c, -1, "invalid arguments")
+		return
+	}
+
+	switch req.Mode {
+	case dnsModeManual:
+		if err := setManualDNS(req.Servers); err != nil {
+			log.Errorf("failed to set manual dns: %s", err)
+			rsp.ErrRsp(c, -2, err.Error())
+			return
+		}
+	case dnsModeDHCP:
+		if err := setDHCPDNS(); err != nil {
+			log.Errorf("failed to set dhcp dns: %s", err)
+			rsp.ErrRsp(c, -3, err.Error())
+			return
+		}
+	default:
+		rsp.ErrRsp(c, -1, "invalid dns mode")
+		return
+	}
+
+	_ = exec.Command("sync").Run()
+
+	rsp.OkRsp(c)
+	log.Debugf("set dns config: mode=%s servers=%v", req.Mode, req.Servers)
+}
+
+func setManualDNS(servers []string) error {
+	normalized, err := validateDNSServers(servers)
+	if err != nil {
+		return err
+	}
+	if len(normalized) == 0 {
+		return fmt.Errorf("dns servers are required")
+	}
+
+	if currentDNSMode() == dnsModeDHCP {
+		if err := refreshDHCPResolvCacheFromEffective(); err != nil {
+			log.Warnf("failed to refresh dhcp dns cache before switching to manual: %s", err)
+		}
+	}
+
+	if err := os.MkdirAll(dnsConfigDir, 0o755); err != nil {
+		return fmt.Errorf("failed to create dns config directory: %w", err)
+	}
+
+	if err := writeDNSMode(dnsModeManual); err != nil {
+		return err
+	}
+
+	if err := os.WriteFile(dnsServersFile, []byte(strings.Join(normalized, "\n")+"\n"), 0o644); err != nil {
+		return fmt.Errorf("failed to write dns servers: %w", err)
+	}
+
+	if err := renderResolvConf(bootResolvFile, normalized); err != nil {
+		return err
+	}
+
+	if err := renderResolvConf(etcResolvFile, normalized); err != nil {
+		return err
+	}
+
+	return installUDHCPCDNSHook()
+}
+
+func setDHCPDNS() error {
+	dhcpConfig, err := readDHCPResolvConfig(currentDNSMode() == dnsModeDHCP)
+	if err != nil {
+		return fmt.Errorf("failed to read dhcp dns: %w", err)
+	}
+	if len(dhcpConfig.Servers) == 0 {
+		return fmt.Errorf("no dhcp dns is currently available")
+	}
+
+	if err := os.MkdirAll(dnsConfigDir, 0o755); err != nil {
+		return fmt.Errorf("failed to create dns config directory: %w", err)
+	}
+
+	if err := renderResolvConfig(dhcpResolvFile, dhcpConfig); err != nil {
+		return fmt.Errorf("failed to write dhcp dns cache: %w", err)
+	}
+
+	if err := writeDNSMode(dnsModeDHCP); err != nil {
+		return err
+	}
+
+	if err := preserveManualDNSServers(); err != nil {
+		return err
+	}
+
+	if err := backupAndRemoveBootResolv(); err != nil {
+		return err
+	}
+
+	if err := renderResolvConfig(etcResolvFile, dhcpConfig); err != nil {
+		return err
+	}
+
+	return installUDHCPCDNSHook()
+}
+
+func currentDNSMode() string {
+	mode := readDNSMode()
+	if mode == "" {
+		mode = defaultDNSMode()
+	}
+
+	return mode
+}
+
+func readDNSMode() string {
+	data, err := os.ReadFile(dnsModeFile)
+	if err != nil {
+		return ""
+	}
+
+	mode := strings.TrimSpace(string(data))
+	if mode != dnsModeManual && mode != dnsModeDHCP {
+		return ""
+	}
+
+	return mode
+}
+
+func defaultDNSMode() string {
+	if _, err := os.Stat(bootResolvFile); err == nil {
+		return dnsModeManual
+	}
+
+	return dnsModeDHCP
+}
+
+func writeDNSMode(mode string) error {
+	if err := os.WriteFile(dnsModeFile, []byte(mode+"\n"), 0o644); err != nil {
+		return fmt.Errorf("failed to write dns mode: %w", err)
+	}
+
+	return nil
+}
+
+func readManualDNSServers() []string {
+	servers, err := parsePlainDNSServers(dnsServersFile)
+	if err != nil {
+		return nil
+	}
+
+	return servers
+}
+
+func preserveManualDNSServers() error {
+	if len(readManualDNSServers()) > 0 {
+		return nil
+	}
+
+	servers, _ := parseResolvConf(bootResolvFile)
+	if len(servers) == 0 {
+		servers, _ = parseResolvConf(bootResolvBackup)
+	}
+	if len(servers) == 0 {
+		return nil
+	}
+
+	if err := os.WriteFile(dnsServersFile, []byte(strings.Join(servers, "\n")+"\n"), 0o644); err != nil {
+		return fmt.Errorf("failed to preserve manual dns servers: %w", err)
+	}
+
+	return nil
+}
+
+func parsePlainDNSServers(path string) ([]string, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	lines := strings.Split(string(data), "\n")
+	return normalizeDNSServers(lines)
+}
+
+func readDHCPResolvConfig(allowEffectiveFallback bool) (resolvConfig, error) {
+	config, err := parseResolvConfig(dhcpResolvFile)
+	if err == nil && len(config.Servers) > 0 {
+		return config, nil
+	}
+
+	if allowEffectiveFallback {
+		effective, effectiveErr := parseResolvConfig(etcResolvFile)
+		if effectiveErr == nil && len(effective.Servers) > 0 {
+			return effective, nil
+		}
+	}
+
+	if err != nil && !os.IsNotExist(err) {
+		return resolvConfig{}, err
+	}
+
+	return resolvConfig{}, nil
+}
+
+func refreshDHCPResolvCacheFromEffective() error {
+	config, err := parseResolvConfig(etcResolvFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	if len(config.Servers) == 0 {
+		return nil
+	}
+	if len(config.SearchDomains) == 0 {
+		cached, _ := parseResolvConfig(dhcpResolvFile)
+		config.SearchDomains = cached.SearchDomains
+	}
+
+	return renderResolvConfig(dhcpResolvFile, config)
+}
+
+func parseResolvConf(path string) ([]string, error) {
+	config, err := parseResolvConfig(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return config.Servers, nil
+}
+
+func parseResolvConfig(path string) (resolvConfig, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return resolvConfig{}, err
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	var servers []string
+	var searchDomains []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := stripInlineComment(scanner.Text())
+		fields := strings.Fields(line)
+		if len(fields) < 2 {
+			continue
+		}
+
+		switch fields[0] {
+		case "nameserver":
+			servers = append(servers, fields[1])
+		case "search":
+			searchDomains = append(searchDomains, fields[1:]...)
+		case "domain":
+			searchDomains = append(searchDomains, fields[1])
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return resolvConfig{}, err
+	}
+
+	normalizedServers, err := normalizeDNSServers(servers)
+	if err != nil {
+		return resolvConfig{}, err
+	}
+
+	return resolvConfig{
+		Servers:       normalizedServers,
+		SearchDomains: normalizeSearchDomains(searchDomains),
+	}, nil
+}
+
+func getDNSInfo() proto.DNSInfo {
+	ifaceName, gateway := getDefaultIPv4Route()
+	if ifaceName == "" {
+		ifaceName = getFallbackIPv4Interface()
+	}
+
+	info := proto.DNSInfo{
+		Interface: ifaceName,
+		Gateway:   gateway,
+	}
+
+	dhcpConfig, _ := readDHCPResolvConfig(currentDNSMode() == dnsModeDHCP)
+	info.SearchDomains = dhcpConfig.SearchDomains
+
+	if ifaceName == "" {
+		return info
+	}
+
+	iface, err := net.InterfaceByName(ifaceName)
+	if err != nil {
+		return info
+	}
+
+	info.Type = getDNSInterfaceType(iface.Name)
+	info.Address, info.SubnetMask = getIPv4AddressInfo(*iface)
+
+	return info
+}
+
+func getDefaultIPv4Route() (string, string) {
+	file, err := os.Open("/proc/net/route")
+	if err != nil {
+		return "", ""
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+		if len(fields) < 8 || fields[1] != "00000000" {
+			continue
+		}
+
+		return fields[0], parseRouteGateway(fields[2])
+	}
+
+	return "", ""
+}
+
+func parseRouteGateway(value string) string {
+	gateway, err := strconv.ParseUint(value, 16, 32)
+	if err != nil || gateway == 0 {
+		return ""
+	}
+
+	return net.IPv4(byte(gateway), byte(gateway>>8), byte(gateway>>16), byte(gateway>>24)).String()
+}
+
+func getFallbackIPv4Interface() string {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return ""
+	}
+
+	for _, iface := range interfaces {
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
+		if getDNSInterfaceType(iface.Name) == "" {
+			continue
+		}
+
+		address, _ := getIPv4AddressInfo(iface)
+		if address != "" {
+			return iface.Name
+		}
+	}
+
+	return ""
+}
+
+func getDNSInterfaceType(name string) string {
+	if strings.HasPrefix(name, "eth") || strings.HasPrefix(name, "en") {
+		return "Wired"
+	}
+
+	if strings.HasPrefix(name, "wlan") || strings.HasPrefix(name, "wl") {
+		return "Wireless"
+	}
+
+	return ""
+}
+
+func getIPv4AddressInfo(iface net.Interface) (string, string) {
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return "", ""
+	}
+
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if !ok {
+			continue
+		}
+
+		ip := ipNet.IP.To4()
+		if ip == nil {
+			continue
+		}
+
+		ones, _ := ipNet.Mask.Size()
+		return fmt.Sprintf("%s/%d", ip.String(), ones), net.IP(ipNet.Mask).String()
+	}
+
+	return "", ""
+}
+
+func renderResolvConf(path string, servers []string) error {
+	return renderResolvConfig(path, resolvConfig{Servers: servers})
+}
+
+func renderResolvConfig(path string, config resolvConfig) error {
+	normalized, err := normalizeDNSServers(config.Servers)
+	if err != nil {
+		return err
+	}
+	if len(normalized) == 0 {
+		return fmt.Errorf("dns servers are required")
+	}
+
+	var builder strings.Builder
+	searchDomains := normalizeSearchDomains(config.SearchDomains)
+	if len(searchDomains) > 0 {
+		builder.WriteString("search ")
+		builder.WriteString(strings.Join(searchDomains, " "))
+		builder.WriteString("\n")
+	}
+
+	for _, server := range normalized {
+		builder.WriteString("nameserver ")
+		builder.WriteString(server)
+		builder.WriteString("\n")
+	}
+
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return fmt.Errorf("failed to create dns file directory: %w", err)
+	}
+
+	if err := os.WriteFile(path, []byte(builder.String()), 0o644); err != nil {
+		return fmt.Errorf("failed to write %s: %w", path, err)
+	}
+
+	return nil
+}
+
+func validateDNSServers(servers []string) ([]string, error) {
+	normalized, err := normalizeDNSServers(servers)
+	if err != nil {
+		return nil, err
+	}
+	if len(normalized) > maxDNSServers {
+		return nil, fmt.Errorf("too many dns servers")
+	}
+
+	return normalized, nil
+}
+
+func normalizeDNSServers(servers []string) ([]string, error) {
+	seen := make(map[string]struct{})
+	var normalized []string
+
+	for _, server := range servers {
+		server = normalizeDNSServer(server)
+		if server == "" {
+			continue
+		}
+
+		ip := net.ParseIP(server)
+		if ip == nil {
+			return nil, fmt.Errorf("invalid dns server: %s", server)
+		}
+
+		server = ip.String()
+		if _, exists := seen[server]; exists {
+			continue
+		}
+
+		seen[server] = struct{}{}
+		normalized = append(normalized, server)
+	}
+
+	return normalized, nil
+}
+
+func normalizeSearchDomains(domains []string) []string {
+	seen := make(map[string]struct{})
+	var normalized []string
+
+	for _, domain := range domains {
+		domain = strings.TrimSpace(domain)
+		if domain == "" {
+			continue
+		}
+		if _, exists := seen[domain]; exists {
+			continue
+		}
+
+		seen[domain] = struct{}{}
+		normalized = append(normalized, domain)
+	}
+
+	return normalized
+}
+
+func normalizeDNSServer(server string) string {
+	server = stripInlineComment(server)
+	server = strings.TrimSpace(server)
+	fields := strings.Fields(server)
+	if len(fields) == 0 {
+		return ""
+	}
+
+	return fields[0]
+}
+
+func stripInlineComment(value string) string {
+	if index := strings.Index(value, "#"); index >= 0 {
+		return value[:index]
+	}
+
+	return value
+}
+
+func backupAndRemoveBootResolv() error {
+	data, err := os.ReadFile(bootResolvFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return fmt.Errorf("failed to read boot resolv: %w", err)
+	}
+
+	if err := os.WriteFile(bootResolvBackup, data, 0o644); err != nil {
+		return fmt.Errorf("failed to backup boot resolv: %w", err)
+	}
+
+	if err := os.Remove(bootResolvFile); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to remove boot resolv: %w", err)
+	}
+
+	return nil
+}
+
+func installUDHCPCDNSHook() error {
+	if err := os.MkdirAll(filepath.Dir(udhcpcHookFile), 0o755); err != nil {
+		return fmt.Errorf("failed to create udhcpc hook directory: %w", err)
+	}
+
+	if err := os.WriteFile(udhcpcHookFile, []byte(udhcpcDNSHook), 0o755); err != nil {
+		return fmt.Errorf("failed to install udhcpc dns hook: %w", err)
+	}
+
+	return nil
+}

server/service/network/scripts/99-nanokvm-dns

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+ACTION="$1"
+CACHE="/etc/resolv.conf.dhcp"
+ACTIVE="/etc/resolv.conf"
+MODE="/etc/kvm/network/dns.mode"
+BOOT="/boot/resolv.conf"
+
+[ "$ACTION" = "bound" ] || [ "$ACTION" = "renew" ] || exit 0
+[ -n "$dns" ] || exit 0
+
+TMPFILE="$(mktemp)" || exit 1
+
+write_search_domain() {
+	if [ -n "$search" ]; then
+		printf "search"
+		for domain_name in $search; do
+			printf " %s" "$domain_name"
+		done
+		printf "\n"
+		return
+	fi
+
+	if [ -n "$domain" ]; then
+		printf "domain %s\n" "$domain"
+		return
+	fi
+
+	for source in "$CACHE" "$ACTIVE"; do
+		[ -f "$source" ] || continue
+		while IFS= read -r line; do
+			line="${line%%#*}"
+			set -- $line
+			[ "$1" = "search" ] || [ "$1" = "domain" ] || continue
+			[ -n "$2" ] || continue
+			printf "%s\n" "$line"
+			return
+		done < "$source"
+	done
+}
+
+{
+	write_search_domain
+	for server in $dns; do
+		printf "nameserver %s\n" "$server"
+	done
+} > "$TMPFILE"
+
+cat "$TMPFILE" > "$CACHE"
+MODE_VALUE="$(cat "$MODE" 2>/dev/null)"
+if [ "$MODE_VALUE" = "dhcp" ] || { [ -z "$MODE_VALUE" ] && [ ! -f "$BOOT" ]; }; then
+	cat "$TMPFILE" > "$ACTIVE"
+fi
+rm -f "$TMPFILE"
+
+exit 0