set dns for tun

internal/util/tun/config.go

@@ -14,4 +14,5 @@ type Config struct {
 	MTU     int
 	Gateway net.IP
 	Router  router.Router
+	DNS []net.IP
 }

listener/tun/metadata.go

@@ -22,30 +22,20 @@ type metadata struct {
 }
 
 func (l *tunListener) parseMetadata(md mdata.Metadata) (err error) {
-	const (
-		name    = "name"
-		netKey  = "net"
-		peer    = "peer"
-		mtu     = "mtu"
-		route   = "route"
-		routes  = "routes"
-		gateway = "gw"
-	)
-
 	config := &tun_util.Config{
-		Name:   mdutil.GetString(md, name),
-		Peer:   mdutil.GetString(md, peer),
-		MTU:    mdutil.GetInt(md, mtu),
-		Router: registry.RouterRegistry().Get(mdutil.GetString(md, "router")),
+		Name:   mdutil.GetString(md, "name", "tun.name"),
+		Peer:   mdutil.GetString(md, "peer", "tun.peer"),
+		MTU:    mdutil.GetInt(md, "mtu", "tun.mtu"),
+		Router: registry.RouterRegistry().Get(mdutil.GetString(md, "router", "tun.router")),
 	}
 	if config.MTU <= 0 {
 		config.MTU = defaultMTU
 	}
-	if gw := mdutil.GetString(md, gateway); gw != "" {
+	if gw := mdutil.GetString(md, "gw", "tun.gw"); gw != "" {
 		config.Gateway = net.ParseIP(gw)
 	}
 
-	for _, s := range strings.Split(mdutil.GetString(md, netKey), ",") {
+	for _, s := range strings.Split(mdutil.GetString(md, "net", "tun.net"), ",") {
 		if s = strings.TrimSpace(s); s == "" {
 			continue
 		}
@@ -59,7 +49,7 @@ func (l *tunListener) parseMetadata(md mdata.Metadata) (err error) {
 		})
 	}
 
-	for _, s := range strings.Split(mdutil.GetString(md, route), ",") {
+	for _, s := range strings.Split(mdutil.GetString(md, "route", "tun.route"), ",") {
 		gw := ""
 		if config.Gateway != nil {
 			gw = config.Gateway.String()
@@ -69,7 +59,7 @@ func (l *tunListener) parseMetadata(md mdata.Metadata) (err error) {
 		}
 	}
 
-	for _, s := range mdutil.GetStrings(md, routes) {
+	for _, s := range mdutil.GetStrings(md, "routes", "tun.routes") {
 		ss := strings.SplitN(s, " ", 2)
 		if len(ss) == 2 {
 			_, ipNet, _ := net.ParseCIDR(strings.TrimSpace(ss[0]))
@@ -94,6 +84,12 @@ func (l *tunListener) parseMetadata(md mdata.Metadata) (err error) {
 		}
 	}
 
+	for _, v := range strings.Split(mdutil.GetString(md, "dns", "tun.dns"), ",") {
+		if ip := net.ParseIP(strings.TrimSpace(v)); ip != nil {
+			config.DNS = append(config.DNS, ip)
+		}
+	}
+
 	if config.Router == nil && len(l.routes) > 0 {
 		config.Router = xrouter.NewRouter(
 			xrouter.RoutesOption(l.routes),

listener/tun/tun_linux.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"os/exec"
+	"strings"
 
 	"github.com/vishvananda/netlink"
 )
@@ -44,6 +46,21 @@ func (l *tunListener) createTun() (dev io.ReadWriteCloser, name string, ip net.I
 		return
 	}
 
+	var dnsServers []string
+	for _, dns := range l.md.config.DNS {
+		dnsServers = append(dnsServers, dns.String())
+	}
+	if len(dnsServers) > 0 {
+		cmd := fmt.Sprintf("resolvectl dns %s %s", name, strings.Join(dnsServers, " "))
+		l.logger.Debug(cmd)
+
+		args := strings.Split(cmd, " ")
+		if er := exec.Command(args[0], args[1:]...).Run(); er != nil {
+			err = fmt.Errorf("%s: %v", cmd, er)
+			return
+		}
+	}
+
 	return
 }
 

listener/tun/tun_windows.go

@@ -40,6 +40,17 @@ func (l *tunListener) createTun() (ifce io.ReadWriteCloser, name string, ip net.
 		return
 	}
 
+	for _, dns := range l.md.config.DNS {
+		cmd := fmt.Sprintf("netsh interface ip add dnsservers name=%s address=%s validate=no", name, dns.String())
+		l.logger.Debug(cmd)
+
+		args := strings.Split(cmd, " ")
+		if er := exec.Command(args[0], args[1:]...).Run(); er != nil {
+			err = fmt.Errorf("%s: %v", cmd, er)
+			return
+		}
+	}
+
 	return
 }