Linux: add option to persist TUN device

main.go

@@ -37,13 +37,14 @@ var (
 
 type CmdArgs struct {
 	// Main
-	Version  *bool
-	TunName  *string
-	TunAddr  *string
-	TunGw    *string
-	TunMask  *string
-	TunDNS   *string
-	LogLevel *string
+	Version    *bool
+	TunName    *string
+	TunAddr    *string
+	TunGw      *string
+	TunMask    *string
+	TunDNS     *string
+	TunPersist *bool
+	LogLevel   *string
 
 	// Proxy
 	ProxyServer *string
@@ -74,6 +75,7 @@ func init() {
 	args.TunGw = flag.String("tunGw", "240.0.0.1", "TUN interface gateway")
 	args.TunMask = flag.String("tunMask", "255.255.255.0", "TUN interface netmask")
 	args.TunDNS = flag.String("tunDNS", "8.8.8.8,8.8.4.4", "DNS resolvers for TUN interface (Windows Only)")
+	args.TunPersist = flag.Bool("tunPersist", false, "Persist TUN interface after the program exits or the last open file descriptor is closed (Linux only)")
 
 	// Proxy
 	args.ProxyServer = flag.String("proxyServer", "", "Proxy server address")
@@ -128,7 +130,7 @@ func main() {
 
 	// Open the tun device
 	dnsServers := strings.Split(*args.TunDNS, ",")
-	tunDev, err := tun.OpenTunDevice(*args.TunName, *args.TunAddr, *args.TunGw, *args.TunMask, dnsServers)
+	tunDev, err := tun.OpenTunDevice(*args.TunName, *args.TunAddr, *args.TunGw, *args.TunMask, dnsServers, *args.TunPersist)
 	if err != nil {
 		log.Fatalf("failed to open tun device: %v", err)
 	}

tun/tun_darwin.go

@@ -30,7 +30,7 @@ func isIPv6(ip net.IP) bool {
 	return false
 }
 
-func OpenTunDevice(name, addr, gw, mask string, dnsServers []string) (io.ReadWriteCloser, error) {
+func OpenTunDevice(name, addr, gw, mask string, dnsServers []string, persist bool) (io.ReadWriteCloser, error) {
 	_ = dnsServers
 	tunDev, err := water.New(water.Config{
 		DeviceType: water.TUN,

tun/tun_linux.go

@@ -8,11 +8,12 @@ import (
 	"github.com/songgao/water"
 )
 
-func OpenTunDevice(name, addr, gw, mask string, dnsServers []string) (io.ReadWriteCloser, error) {
+func OpenTunDevice(name, addr, gw, mask string, dnsServers []string, persist bool) (io.ReadWriteCloser, error) {
 	cfg := water.Config{
 		DeviceType: water.TUN,
 	}
 	cfg.Name = name
+	cfg.Persist = persist
 	tunDev, err := water.New(cfg)
 	if err != nil {
 		return nil, err

tun/tun_windows.go

@@ -157,7 +157,7 @@ func getTuntapComponentId(ifaceName string) (string, string, error) {
 	return "", "", errors.New("not found component id")
 }
 
-func OpenTunDevice(name, addr, gw, mask string, dns []string) (io.ReadWriteCloser, error) {
+func OpenTunDevice(name, addr, gw, mask string, dns []string, persist bool) (io.ReadWriteCloser, error) {
 	componentId, devName, err := getTuntapComponentId(name)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get component ID: %v", err)