feat: add bind interface

fix: clone route without interface and mark config

chain.go

@@ -20,6 +20,7 @@ type Chain struct {
 	isRoute    bool
 	Retries    int
 	Mark       int
+	Interface  string
 	nodeGroups []*NodeGroup
 	route      []Node // nodes in the selected route
 }
@@ -36,9 +37,11 @@ func NewChain(nodes ...Node) *Chain {
 
 // newRoute creates a chain route.
 // a chain route is the final route after node selection.
-func newRoute(nodes ...Node) *Chain {
+func (c *Chain) newRoute(nodes ...Node) *Chain {
 	chain := NewChain(nodes...)
 	chain.isRoute = true
+	chain.Interface = c.Interface
+	chain.Mark = c.Mark
 	return chain
 }
 
@@ -166,6 +169,18 @@ func (c *Chain) dialWithOptions(ctx context.Context, network, address string, op
 		}
 	}
 
+	if c.Interface != "" {
+		controlFunction = func(_, _ string, cc syscall.RawConn) error {
+			return cc.Control(func(fd uintptr) {
+				err := setSocketInterface(int(fd), c.Interface)
+
+				if err != nil {
+					log.Logf("net dialer set interface %s error: %s", c.Interface, err)
+				}
+			})
+		}
+	}
+
 	if route.IsEmpty() {
 		switch network {
 		case "udp", "udp4", "udp6":
@@ -303,13 +318,13 @@ func (c *Chain) selectRoute() (route *Chain, err error) {
 // selectRouteFor selects route with bypass testing.
 func (c *Chain) selectRouteFor(addr string) (route *Chain, err error) {
 	if c.IsEmpty() {
-		return newRoute(), nil
+		return c.newRoute(), nil
 	}
 	if c.isRoute {
 		return c, nil
 	}
 
-	route = newRoute()
+	route = c.newRoute()
 	var nl []Node
 
 	for _, group := range c.nodeGroups {
@@ -327,7 +342,7 @@ func (c *Chain) selectRouteFor(addr string) (route *Chain, err error) {
 			node.DialOptions = append(node.DialOptions,
 				ChainDialOption(route),
 			)
-			route = newRoute() // cutoff the chain for multiplex node.
+			route = c.newRoute() // cutoff the chain for multiplex node.
 		}
 
 		route.AddNode(node)

cmd/gost/main.go

@@ -33,6 +33,7 @@ func init() {
 	flag.Var(&baseCfg.route.ServeNodes, "L", "listen address, can listen on multiple ports (required)")
 	flag.IntVar(&baseCfg.route.Mark, "M", 0, "Specify out connection mark")
 	flag.StringVar(&configureFile, "C", "", "configure file")
+	flag.StringVar(&baseCfg.route.Interface, "I", "", "Interface to bind")
 	flag.BoolVar(&baseCfg.Debug, "D", false, "enable debug log")
 	flag.BoolVar(&printVersion, "V", false, "print version")
 	if pprofEnabled {

cmd/gost/route.go

@@ -31,12 +31,14 @@ type route struct {
 	ChainNodes stringList
 	Retries    int
 	Mark       int
+	Interface  string
 }
 
 func (r *route) parseChain() (*gost.Chain, error) {
 	chain := gost.NewChain()
 	chain.Retries = r.Retries
 	chain.Mark = r.Mark
+	chain.Interface = r.Interface
 	gid := 1 // group ID
 
 	for _, ns := range r.ChainNodes {

sockopts_linux.go

@@ -5,3 +5,7 @@ import "syscall"
 func setSocketMark(fd int, value int) (e error) {
 	return syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_MARK, value)
 }
+
+func setSocketInterface(fd int, value string) (e error) {
+	return syscall.SetsockoptString(fd, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, value)
+}

sockopts_other.go

@@ -5,3 +5,7 @@ package gost
 func setSocketMark(fd int, value int) (e error) {
 	return nil
 }
+
+func setSocketInterface(fd int, value string) (e error) {
+	return nil
+}