Add darwin bind support

common/control/bind_darwin.go

@@ -0,0 +1,55 @@
+package control
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func NewBindManager() BindManager {
+	return &myBindManager{
+		interfaceIndexByName: make(map[string]int),
+	}
+}
+
+func BindToInterface(manager BindManager, interfaceName string) Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		index, err := manager.IndexByName(interfaceName)
+		if err != nil {
+			return err
+		}
+		return bindToInterface(conn, network, index)
+	}
+}
+
+func BindToInterfaceFunc(manager BindManager, interfaceNameFunc func() string) Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		interfaceName := interfaceNameFunc()
+		if interfaceName == "" {
+			return nil
+		}
+		index, err := manager.IndexByName(interfaceName)
+		if err != nil {
+			return err
+		}
+		return bindToInterface(conn, network, index)
+	}
+}
+
+func BindToInterfaceIndexFunc(interfaceIndexFunc func() int) Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		index := interfaceIndexFunc()
+		return bindToInterface(conn, network, index)
+	}
+}
+
+func bindToInterface(conn syscall.RawConn, network string, index int) error {
+	return Control(conn, func(fd uintptr) error {
+		switch network {
+		case "tcp6", "udp6":
+			return unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_BOUND_IF, index)
+		default:
+			return unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, index)
+		}
+	})
+}