1 /* SPDX-License-Identifier: MIT
2 *
3 * Copyright (C) 2017-2025 WireGuard LLC. All Rights Reserved.
4 */
5 6 package tun
7 8 import (
9 "os"
10 )
11 12 type Event int
13 14 const (
15 EventUp = 1 << iota
16 EventDown
17 EventMTUUpdate
18 )
19 20 type Device interface {
21 // File returns the file descriptor of the device.
22 File() *os.File
23 24 // Read one or more packets from the Device (without any additional headers).
25 // On a successful read it returns the number of packets read, and sets
26 // packet lengths within the sizes slice. len(sizes) must be >= len(bufs).
27 // A nonzero offset can be used to instruct the Device on where to begin
28 // reading into each element of the bufs slice.
29 Read(bufs [][]byte, sizes []int, offset int) (n int, err error)
30 31 // Write one or more packets to the device (without any additional headers).
32 // On a successful write it returns the number of packets written. A nonzero
33 // offset can be used to instruct the Device on where to begin writing from
34 // each packet contained within the bufs slice.
35 Write(bufs [][]byte, offset int) (int, error)
36 37 // MTU returns the MTU of the Device.
38 MTU() (int, error)
39 40 // Name returns the current name of the Device.
41 Name() (string, error)
42 43 // Events returns a channel of type Event, which is fed Device events.
44 Events() <-chan Event
45 46 // Close stops the Device and closes the Event channel.
47 Close() error
48 49 // BatchSize returns the preferred/max number of packets that can be read or
50 // written in a single read/write call. BatchSize must not change over the
51 // lifetime of a Device.
52 BatchSize() int
53 }
54