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1/* Copyright (C) 1991-2025 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#ifndef _NETINET_IP6_H
19#define _NETINET_IP6_H 1
20
21#include <inttypes.h>
22#include <netinet/in.h>
23
24struct ip6_hdr
25 {
26 union
27 {
28 struct ip6_hdrctl
29 {
30 uint32_t ip6_un1_flow; /* 4 bits version, 8 bits TC,
31 20 bits flow-ID */
32 uint16_t ip6_un1_plen; /* payload length */
33 uint8_t ip6_un1_nxt; /* next header */
34 uint8_t ip6_un1_hlim; /* hop limit */
35 } ip6_un1;
36 uint8_t ip6_un2_vfc; /* 4 bits version, top 4 bits tclass */
37 } ip6_ctlun;
38 struct in6_addr ip6_src; /* source address */
39 struct in6_addr ip6_dst; /* destination address */
40 };
41
42#define ip6_vfc ip6_ctlun.ip6_un2_vfc
43#define ip6_flow ip6_ctlun.ip6_un1.ip6_un1_flow
44#define ip6_plen ip6_ctlun.ip6_un1.ip6_un1_plen
45#define ip6_nxt ip6_ctlun.ip6_un1.ip6_un1_nxt
46#define ip6_hlim ip6_ctlun.ip6_un1.ip6_un1_hlim
47#define ip6_hops ip6_ctlun.ip6_un1.ip6_un1_hlim
48
49#define IPV6_VERSION 0x60
50#define IPV6_VERSION_MASK 0xf0
51
52#if __BYTE_ORDER == __BIG_ENDIAN
53#define IPV6_FLOWINFO_MASK 0x0fffffff /* flow info (28 bits) */
54#define IPV6_FLOWLABEL_MASK 0x000fffff /* flow label (20 bits) */
55#else /* __BYTE_ORDER == __LITTLE_ENDIAN */
56#define IPV6_FLOWINFO_MASK 0xffffff0f /* flow info (28 bits) */
57#define IPV6_FLOWLABEL_MASK 0xffff0f00 /* flow label (20 bits) */
58#endif
59
60/* Generic extension header. */
61struct ip6_ext
62 {
63 uint8_t ip6e_nxt; /* next header. */
64 uint8_t ip6e_len; /* length in units of 8 octets. */
65 };
66
67/* Hop-by-Hop options header. */
68struct ip6_hbh
69 {
70 uint8_t ip6h_nxt; /* next header. */
71 uint8_t ip6h_len; /* length in units of 8 octets. */
72 /* followed by options */
73 };
74
75/* Destination options header */
76struct ip6_dest
77 {
78 uint8_t ip6d_nxt; /* next header */
79 uint8_t ip6d_len; /* length in units of 8 octets */
80 /* followed by options */
81 };
82
83/* Routing header */
84struct ip6_rthdr
85 {
86 uint8_t ip6r_nxt; /* next header */
87 uint8_t ip6r_len; /* length in units of 8 octets */
88 uint8_t ip6r_type; /* routing type */
89 uint8_t ip6r_segleft; /* segments left */
90 /* followed by routing type specific data */
91 };
92
93/* Type 0 Routing header */
94struct ip6_rthdr0
95 {
96 uint8_t ip6r0_nxt; /* next header */
97 uint8_t ip6r0_len; /* length in units of 8 octets */
98 uint8_t ip6r0_type; /* always zero */
99 uint8_t ip6r0_segleft; /* segments left */
100 uint8_t ip6r0_reserved; /* reserved field */
101 uint8_t ip6r0_slmap[3]; /* strict/loose bit map */
102 /* followed by up to 127 struct in6_addr */
103 struct in6_addr ip6r0_addr[0];
104 };
105
106/* Fragment header */
107struct ip6_frag
108 {
109 uint8_t ip6f_nxt; /* next header */
110 uint8_t ip6f_reserved; /* reserved field */
111 uint16_t ip6f_offlg; /* offset, reserved, and flag */
112 uint32_t ip6f_ident; /* identification */
113 };
114
115#if __BYTE_ORDER == __BIG_ENDIAN
116# define IP6F_OFF_MASK 0xfff8 /* mask out offset from _offlg */
117# define IP6F_RESERVED_MASK 0x0006 /* reserved bits in ip6f_offlg */
118# define IP6F_MORE_FRAG 0x0001 /* more-fragments flag */
119#else /* __BYTE_ORDER == __LITTLE_ENDIAN */
120# define IP6F_OFF_MASK 0xf8ff /* mask out offset from _offlg */
121# define IP6F_RESERVED_MASK 0x0600 /* reserved bits in ip6f_offlg */
122# define IP6F_MORE_FRAG 0x0100 /* more-fragments flag */
123#endif
124
125/* IPv6 options */
126struct ip6_opt
127 {
128 uint8_t ip6o_type;
129 uint8_t ip6o_len;
130 };
131
132/* The high-order 3 bits of the option type define the behavior
133 * when processing an unknown option and whether or not the option
134 * content changes in flight.
135 */
136#define IP6OPT_TYPE(o) ((o) & 0xc0)
137#define IP6OPT_TYPE_SKIP 0x00
138#define IP6OPT_TYPE_DISCARD 0x40
139#define IP6OPT_TYPE_FORCEICMP 0x80
140#define IP6OPT_TYPE_ICMP 0xc0
141#define IP6OPT_TYPE_MUTABLE 0x20
142
143/* Special option types for padding. */
144#define IP6OPT_PAD1 0
145#define IP6OPT_PADN 1
146
147#define IP6OPT_JUMBO 0xc2
148#define IP6OPT_NSAP_ADDR 0xc3
149#define IP6OPT_TUNNEL_LIMIT 0x04
150#define IP6OPT_ROUTER_ALERT 0x05
151
152/* Jumbo Payload Option */
153struct ip6_opt_jumbo
154 {
155 uint8_t ip6oj_type;
156 uint8_t ip6oj_len;
157 uint8_t ip6oj_jumbo_len[4];
158 };
159#define IP6OPT_JUMBO_LEN 6
160
161/* NSAP Address Option */
162struct ip6_opt_nsap
163 {
164 uint8_t ip6on_type;
165 uint8_t ip6on_len;
166 uint8_t ip6on_src_nsap_len;
167 uint8_t ip6on_dst_nsap_len;
168 /* followed by source NSAP */
169 /* followed by destination NSAP */
170 };
171
172/* Tunnel Limit Option */
173struct ip6_opt_tunnel
174 {
175 uint8_t ip6ot_type;
176 uint8_t ip6ot_len;
177 uint8_t ip6ot_encap_limit;
178 };
179
180/* Router Alert Option */
181struct ip6_opt_router
182 {
183 uint8_t ip6or_type;
184 uint8_t ip6or_len;
185 uint8_t ip6or_value[2];
186 };
187
188/* Router alert values (in network byte order) */
189#if __BYTE_ORDER == __BIG_ENDIAN
190# define IP6_ALERT_MLD 0x0000
191# define IP6_ALERT_RSVP 0x0001
192# define IP6_ALERT_AN 0x0002
193#else /* __BYTE_ORDER == __LITTLE_ENDIAN */
194# define IP6_ALERT_MLD 0x0000
195# define IP6_ALERT_RSVP 0x0100
196# define IP6_ALERT_AN 0x0200
197#endif
198
199#endif /* netinet/ip6.h */