1/* $OpenBSD: if_tun.h,v 1.18 2024/11/17 00:25:07 dlg Exp $ */
2
3/*
4 * Copyright (c) 1988, Julian Onions <Julian.Onions@nexor.co.uk>
5 * Nottingham University 1987.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef _NET_IF_TUN_H_
30#define _NET_IF_TUN_H_
31
32#include <sys/ioccom.h>
33
34/*
35 * tun_hdr is a multiple of 4 bytes, but is built out of uint16_t
36 * fields. This allows it to sit on a 2 byte boundary in front of
37 * either IP (and MPLS) or Ethernet packets for tun(4) and tap(4)
38 * interfaces respectively while maintaining the alignment of their
39 * payloads.
40 *
41 * Userland can request the use of the tun_hdr using the TUNSCAP
42 * ioctl. This ioctl also allows userland to specify which "offload"
43 * capabilities it is able to accept in packets it will read from the
44 * kernel. It is acceptable to enable tun_hdr without enabling any
45 * interface offload capabilities.
46 *
47 * Once the tap_hdr is enabled, userland can write packets into the
48 * kernel with any of the supported features. tun(4)/tap(4) reads
49 * will unconditionally handle any features specified on the packet,
50 * regardless of what capabilities were specified by the TUNSCAP
51 * ioctl.
52 *
53 * The tun_hdr can be read from one interface and written directly
54 * to another without interpretation or modification.
55 *
56 * Use of tun_hdr and the associated capabilities are reset when a
57 * tun(4)/tap(4) device is closed.
58 */
59
60struct tun_hdr {
61 uint16_t th_flags;
62#define TUN_H_PRIO_MASK 0x7
63#define TUN_H_VTAG (1 << 4) /* th_vtag is set */
64#define TUN_H_TCP_MSS (1 << 5) /* Cut TCP frame up by th_mss */
65
66#define TUN_H_IPV4_CSUM (1 << 8)
67#define TUN_H_TCP_CSUM (1 << 9)
68#define TUN_H_UDP_CSUM (1 << 10)
69#define TUN_H_ICMP_CSUM (1 << 11)
70
71 uint16_t th_pad;
72
73 uint16_t th_vtag;
74 uint16_t th_mss;
75};
76
77#define TUN_OPEN 0x0001
78#define TUN_INITED 0x0002
79#define TUN_RCOLL 0x0004 /* unused */
80#define TUN_IASET 0x0008
81#define TUN_DSTADDR 0x0010
82#define TUN_RWAIT 0x0040
83#define TUN_ASYNC 0x0080
84#define TUN_NBIO 0x0100
85#define TUN_BRDADDR 0x0200
86#define TUN_STAYUP 0x0400
87#define TUN_LAYER2 0x0800
88
89#define TUN_READY (TUN_OPEN | TUN_INITED)
90
91/* Maximum packet size */
92#define TUNMTU 3000
93
94/* Maximum receive packet size (hard limit) */
95#define TUNMRU 16384
96
97/* iface info */
98struct tuninfo {
99 u_int mtu;
100 u_short type;
101 u_short flags;
102 u_int baudrate;
103};
104#define TUNSIFINFO _IOW('t', 91, struct tuninfo)
105#define TUNGIFINFO _IOR('t', 92, struct tuninfo)
106
107/* ioctl for changing the broadcast/point-to-point status */
108#define TUNSIFMODE _IOW('t', 93, int)
109
110/* ioctl's for get/set debug */
111#define TUNSDEBUG _IOW('t', 94, int)
112#define TUNGDEBUG _IOR('t', 95, int)
113
114struct tun_capabilities {
115 uint32_t tun_if_capabilities; /* IFCAP_* from net/if.h */
116};
117
118#define TUNSCAP _IOW('t', 196, struct tun_capabilities)
119#define TUNGCAP _IOR('t', 196, struct tun_capabilities)
120#define TUNDCAP _IO('t', 196)
121
122#endif /* _NET_IF_TUN_H_ */