Refactor: new dialer impl

component/dialer/dialer.go

@@ -3,20 +3,56 @@ package dialer
 import (
 	"context"
 	"net"
+	"syscall"
+
+	"go.uber.org/atomic"
 )
 
-func Dial(network, address string) (net.Conn, error) {
-	return DialContext(context.Background(), network, address)
+var (
+	DefaultInterfaceName = atomic.NewString("")
+	DefaultRoutingMark   = atomic.NewInt32(0)
+)
+
+type Options struct {
+	// InterfaceName is the name of interface/device to bind.
+	// If a socket is bound to an interface, only packets received
+	// from that particular interface are processed by the socket.
+	InterfaceName string
+
+	// RoutingMark is the mark for each packet sent through this
+	// socket. Changing the mark can be used for mark-based routing
+	// without netfilter or for packet filtering.
+	RoutingMark int
 }
 
 func DialContext(ctx context.Context, network, address string) (net.Conn, error) {
-	d := &net.Dialer{}
-	setControl(d)
+	return DialContextWithOptions(ctx, network, address, &Options{
+		InterfaceName: DefaultInterfaceName.Load(),
+		RoutingMark:   int(DefaultRoutingMark.Load()),
+	})
+}
+
+func DialContextWithOptions(ctx context.Context, network, address string, opts *Options) (net.Conn, error) {
+	d := &net.Dialer{
+		Control: func(network, address string, c syscall.RawConn) error {
+			return setSocketOptions(network, address, c, opts)
+		},
+	}
 	return d.DialContext(ctx, network, address)
 }
 
 func ListenPacket(network, address string) (net.PacketConn, error) {
-	lc := &net.ListenConfig{}
-	setControl(lc)
+	return ListenPacketWithOptions(network, address, &Options{
+		InterfaceName: DefaultInterfaceName.Load(),
+		RoutingMark:   int(DefaultRoutingMark.Load()),
+	})
+}
+
+func ListenPacketWithOptions(network, address string, opts *Options) (net.PacketConn, error) {
+	lc := &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			return setSocketOptions(network, address, c, opts)
+		},
+	}
 	return lc.ListenPacket(context.Background(), network, address)
 }