feat: add custom dns support

cli.go

@@ -21,6 +21,8 @@ var (
 	pprof     bool
 	natServer string
 	account   string
+	dnsServer string
+	enableDNS bool
 )
 
 var (
@@ -36,16 +38,10 @@ func init() {
 	flag.BoolVar(&pprof, "pprof", false, "enable pprof")
 	flag.StringVar(&natServer, "natServer", common.DefNatAddr, "natServer")
 	flag.StringVar(&account, "account", "unknown", "account")
+	flag.StringVar(&dnsServer, "dnsServer", common.DNSServer, "custom dns server")
+	flag.BoolVar(&enableDNS, "enableDns", false, "enable custom dns server")
 
 	flag.Parse()
-
-	// for android
-	net.DefaultResolver = &net.Resolver{
-		PreferGo: true,
-		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
-			return net.Dial("udp", common.DNSServer)
-		},
-	}
 }
 
 func initPprof() {
@@ -56,6 +52,16 @@ func initPprof() {
 		log.Printf("enable pprof: %s", common.PprofAddr)
 		log.Fatal(http.ListenAndServe(common.PprofAddr, nil))
 	}()
+
+	// for android
+	if enableDNS {
+		net.DefaultResolver = &net.Resolver{
+			PreferGo: true,
+			Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+				return net.Dial("udp", dnsServer)
+			},
+		}
+	}
 }
 
 func main() {