Feature: add fwmark support

component/dialer/bind.go

@@ -1,8 +1,11 @@
 package dialer
 
-import "net"
+import (
+	"net"
+	"sync"
+)
 
-var _boundInterface *net.Interface
+var _bindOnce sync.Once
 
 // BindToInterface binds dialer to specific interface.
 func BindToInterface(name string) error {
@@ -10,6 +13,9 @@ func BindToInterface(name string) error {
 	if err != nil {
 		return err
 	}
-	_boundInterface = i
+
+	_bindOnce.Do(func() {
+		addControl(bindToInterface(i))
+	})
 	return nil
 }

component/dialer/bind_darwin.go

@@ -7,7 +7,8 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func bindToInterface(network, address string, c syscall.RawConn) error {
+func bindToInterface(i *net.Interface) controlFunc {
+	return func(network, address string, c syscall.RawConn) error {
 		ipStr, _, _ := net.SplitHostPort(address)
 		if ip := net.ParseIP(ipStr); ip != nil && !ip.IsGlobalUnicast() {
 			return nil
@@ -16,9 +17,10 @@ func bindToInterface(network, address string, c syscall.RawConn) error {
 		return c.Control(func(fd uintptr) {
 			switch network {
 			case "tcp4", "udp4":
-			unix.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_BOUND_IF, _boundInterface.Index)
+				unix.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_BOUND_IF, i.Index)
 			case "tcp6", "udp6":
-			unix.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IPV6_BOUND_IF, _boundInterface.Index)
+				unix.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IPV6_BOUND_IF, i.Index)
 			}
 		})
 	}
+}

component/dialer/bind_linux.go

@@ -7,13 +7,15 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func bindToInterface(network, address string, c syscall.RawConn) error {
+func bindToInterface(i *net.Interface) controlFunc {
+	return func(network, address string, c syscall.RawConn) error {
 		ipStr, _, _ := net.SplitHostPort(address)
 		if ip := net.ParseIP(ipStr); ip != nil && !ip.IsGlobalUnicast() {
 			return nil
 		}
 
 		return c.Control(func(fd uintptr) {
-		unix.BindToDevice(int(fd), _boundInterface.Name)
+			unix.BindToDevice(int(fd), i.Name)
 		})
 	}
+}

component/dialer/bind_others.go

@@ -4,9 +4,12 @@ package dialer
 
 import (
 	"errors"
+	"net"
 	"syscall"
 )
 
-func bindToInterface(network, address string, c syscall.RawConn) error {
+func bindToInterface(_ *net.Interface) controlFunc {
+	return func(string, string, syscall.RawConn) error {
 		return errors.New("unsupported platform")
 	}
+}

component/dialer/control.go

@@ -0,0 +1,37 @@
+package dialer
+
+import (
+	"errors"
+	"net"
+	"syscall"
+)
+
+type controlFunc func(string, string, syscall.RawConn) error
+
+var (
+	_controlPool = make([]controlFunc, 0, 2)
+)
+
+func addControl(f controlFunc) {
+	_controlPool = append(_controlPool, f)
+}
+
+func setControl(i interface{}) {
+	control := func(address, network string, c syscall.RawConn) error {
+		for _, f := range _controlPool {
+			if err := f(address, network, c); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	switch v := i.(type) {
+	case *net.Dialer:
+		v.Control = control
+	case *net.ListenConfig:
+		v.Control = control
+	default:
+		panic(errors.New("wrong type"))
+	}
+}

component/dialer/dialer.go

@@ -11,20 +11,12 @@ func Dial(network, address string) (net.Conn, error) {
 
 func DialContext(ctx context.Context, network, address string) (net.Conn, error) {
 	d := &net.Dialer{}
-
-	if _boundInterface != nil {
-		d.Control = bindToInterface
-	}
-
+	setControl(d)
 	return d.DialContext(ctx, network, address)
 }
 
 func ListenPacket(network, address string) (net.PacketConn, error) {
 	lc := &net.ListenConfig{}
-
-	if _boundInterface != nil {
-		lc.Control = bindToInterface
-	}
-
+	setControl(lc)
 	return lc.ListenPacket(context.Background(), network, address)
 }

component/dialer/fwmark.go

@@ -0,0 +1,14 @@
+package dialer
+
+import (
+	"sync"
+)
+
+var _setOnce sync.Once
+
+// SetMark sets the mark for each packet sent through this dialer(socket).
+func SetMark(i int) {
+	_setOnce.Do(func() {
+		addControl(setMark(i))
+	})
+}

component/dialer/fwmark_linux.go

@@ -0,0 +1,15 @@
+package dialer
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func setMark(i int) controlFunc {
+	return func(_, _ string, c syscall.RawConn) error {
+		return c.Control(func(fd uintptr) {
+			unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, i)
+		})
+	}
+}

component/dialer/fwmark_others.go

@@ -0,0 +1,14 @@
+// +build !linux
+
+package dialer
+
+import (
+	"errors"
+	"syscall"
+)
+
+func setMark(_ int) controlFunc {
+	return func(string, string, syscall.RawConn) error {
+		return errors.New("fwmark: linux only")
+	}
+}

engine/engine.go

@@ -31,6 +31,7 @@ func Insert(k *Key) {
 
 type Key struct {
 	MTU       uint32
+	Mark      int
 	Proxy     string
 	Stats     string
 	Token     string
@@ -60,6 +61,7 @@ func (e *engine) start() error {
 
 	for _, f := range []func() error{
 		e.setLogLevel,
+		e.setMark,
 		e.setInterface,
 		e.setStats,
 		e.setProxy,
@@ -93,12 +95,20 @@ func (e *engine) setLogLevel() error {
 	return nil
 }
 
+func (e *engine) setMark() error {
+	if e.Mark != 0 {
+		dialer.SetMark(e.Mark)
+		log.Infof("[DIALER] set fwmark: %d", e.Mark)
+	}
+	return nil
+}
+
 func (e *engine) setInterface() error {
 	if e.Interface != "" {
 		if err := dialer.BindToInterface(e.Interface); err != nil {
 			return err
 		}
-		log.Infof("[BOUND] bind to interface: %s", e.Interface)
+		log.Infof("[DIALER] use interface: %s", e.Interface)
 	}
 	return nil
 }
@@ -108,7 +118,7 @@ func (e *engine) setStats() error {
 		go func() {
 			_ = stats.Start(e.Stats, e.Token)
 		}()
-		log.Infof("[STATS] stats server listen at: http://%s", e.Stats)
+		log.Infof("[STATS] serve at: http://%s", e.Stats)
 	}
 	return nil
 }

main.go

@@ -15,12 +15,13 @@ var key = new(engine.Key)
 
 func init() {
 	flag.StringVarP(&key.Device, "device", "d", "", "use this device [driver://]name")
+	flag.IntVar(&key.Mark, "fwmark", 0, "set firewall MARK (Linux only)")
 	flag.StringVarP(&key.Interface, "interface", "i", "", "use network INTERFACE (Linux/MacOS only)")
-	flag.StringVarP(&key.Proxy, "proxy", "p", "", "use this proxy [protocol://]host[:port]")
 	flag.StringVarP(&key.LogLevel, "loglevel", "l", "info", "log level [debug|info|warn|error|silent]")
+	flag.Uint32VarP(&key.MTU, "mtu", "m", 0, "set device maximum transmission unit (MTU)")
+	flag.StringVarP(&key.Proxy, "proxy", "p", "", "use this proxy [protocol://]host[:port]")
 	flag.StringVar(&key.Stats, "stats", "", "HTTP statistic server listen address")
 	flag.StringVar(&key.Token, "token", "", "HTTP statistic server auth token")
-	flag.Uint32VarP(&key.MTU, "mtu", "m", 0, "set device maximum transmission unit (MTU)")
 	flag.BoolVarP(&key.Version, "version", "v", false, "show version information and quit")
 	flag.Parse()
 }