boundif: introduce API for socket binding

device/boundif_android.go

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+func (device *Device) PeekLookAtSocketFd4() (fd int, err error) {
+	sysconn, err := device.net.bind.(*nativeBind).ipv4.SyscallConn()
+	if err != nil {
+		return
+	}
+	err = sysconn.Control(func(f uintptr) {
+		fd = int(f)
+	})
+	if err != nil {
+		return
+	}
+	return
+}
+
+func (device *Device) PeekLookAtSocketFd6() (fd int, err error) {
+	sysconn, err := device.net.bind.(*nativeBind).ipv6.SyscallConn()
+	if err != nil {
+		return
+	}
+	err = sysconn.Control(func(f uintptr) {
+		fd = int(f)
+	})
+	if err != nil {
+		return
+	}
+	return
+}