boundif: introduce API for socket binding

device/boundif_darwin.go

@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+func (device *Device) BindSocketToInterface4(interfaceIndex uint32) error {
+	sysconn, err := device.net.bind.(*nativeBind).ipv4.SyscallConn()
+	if err != nil {
+		return nil
+	}
+	err2 := sysconn.Control(func(fd uintptr) {
+		err = unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, int(interfaceIndex))
+	})
+	if err2 != nil {
+		return err2
+	}
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (device *Device) BindSocketToInterface6(interfaceIndex uint32) error {
+	sysconn, err := device.net.bind.(*nativeBind).ipv4.SyscallConn()
+	if err != nil {
+		return nil
+	}
+	err2 := sysconn.Control(func(fd uintptr) {
+		err = unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_BOUND_IF, int(interfaceIndex))
+	})
+	if err2 != nil {
+		return err2
+	}
+	if err != nil {
+		return err
+	}
+	return nil
+}