1/* Copyright (C) 2006-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2006.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <string.h>
20#include <netinet/in.h>
21#include <netinet/ip6.h>
22
23
24/* RFC 3542, 7.1
25
26 This function returns the number of bytes required to hold a
27 Routing header of the specified type containing the specified
28 number of segments (addresses). For an IPv6 Type 0 Routing header,
29 the number of segments must be between 0 and 127, inclusive. */
30socklen_t
31inet6_rth_space (int type, int segments)
32{
33 switch (type)
34 {
35 case IPV6_RTHDR_TYPE_0:
36 if (segments < 0 || segments > 127)
37 return 0;
38
39 return sizeof (struct ip6_rthdr0) + segments * sizeof (struct in6_addr);
40 }
41
42 return 0;
43}
44
45
46/* RFC 3542, 7.2
47
48 This function initializes the buffer pointed to by BP to contain a
49 Routing header of the specified type and sets ip6r_len based on the
50 segments parameter. */
51void *
52inet6_rth_init (void *bp, socklen_t bp_len, int type, int segments)
53{
54 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
55
56 switch (type)
57 {
58 case IPV6_RTHDR_TYPE_0:
59 /* Make sure the parameters are valid and the buffer is large enough. */
60 if (segments < 0 || segments > 127)
61 break;
62
63 socklen_t len = (sizeof (struct ip6_rthdr0)
64 + segments * sizeof (struct in6_addr));
65 if (len > bp_len)
66 break;
67
68 /* Some implementations seem to initialize the whole memory area. */
69 memset (bp, '\0', len);
70
71 /* Length in units of 8 octets. */
72 rthdr->ip6r_len = segments * sizeof (struct in6_addr) / 8;
73 rthdr->ip6r_type = IPV6_RTHDR_TYPE_0;
74 return bp;
75 }
76
77 return NULL;
78}
79
80
81/* RFC 3542, 7.3
82
83 This function adds the IPv6 address pointed to by addr to the end of
84 the Routing header being constructed. */
85int
86inet6_rth_add (void *bp, const struct in6_addr *addr)
87{
88 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
89
90 switch (rthdr->ip6r_type)
91 {
92 struct ip6_rthdr0 *rthdr0;
93 case IPV6_RTHDR_TYPE_0:
94 rthdr0 = (struct ip6_rthdr0 *) rthdr;
95 if (rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr)
96 - rthdr0->ip6r0_segleft < 1)
97 return -1;
98
99 memcpy (&rthdr0->ip6r0_addr[rthdr0->ip6r0_segleft++],
100 addr, sizeof (struct in6_addr));
101
102 return 0;
103 }
104
105 return -1;
106}
107
108
109/* RFC 3542, 7.4
110
111 This function takes a Routing header extension header (pointed to by
112 the first argument) and writes a new Routing header that sends
113 datagrams along the reverse of that route. The function reverses the
114 order of the addresses and sets the segleft member in the new Routing
115 header to the number of segments. */
116int
117inet6_rth_reverse (const void *in, void *out)
118{
119 struct ip6_rthdr *in_rthdr = (struct ip6_rthdr *) in;
120
121 switch (in_rthdr->ip6r_type)
122 {
123 struct ip6_rthdr0 *in_rthdr0;
124 struct ip6_rthdr0 *out_rthdr0;
125 case IPV6_RTHDR_TYPE_0:
126 in_rthdr0 = (struct ip6_rthdr0 *) in;
127 out_rthdr0 = (struct ip6_rthdr0 *) out;
128
129 /* Copy header, not the addresses. The memory regions can overlap. */
130 memmove (out_rthdr0, in_rthdr0, sizeof (struct ip6_rthdr0));
131
132 int total = in_rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr);
133 for (int i = 0; i < total / 2; ++i)
134 {
135 /* Remember, IN_RTHDR0 and OUT_RTHDR0 might overlap. */
136 struct in6_addr temp = in_rthdr0->ip6r0_addr[i];
137 out_rthdr0->ip6r0_addr[i] = in_rthdr0->ip6r0_addr[total - 1 - i];
138 out_rthdr0->ip6r0_addr[total - 1 - i] = temp;
139 }
140 if (total % 2 != 0 && in != out)
141 out_rthdr0->ip6r0_addr[total / 2] = in_rthdr0->ip6r0_addr[total / 2];
142
143 out_rthdr0->ip6r0_segleft = total;
144
145 return 0;
146 }
147
148 return -1;
149}
150
151
152/* RFC 3542, 7.5
153
154 This function returns the number of segments (addresses) contained in
155 the Routing header described by BP. */
156int
157inet6_rth_segments (const void *bp)
158{
159 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
160
161 switch (rthdr->ip6r_type)
162 {
163 case IPV6_RTHDR_TYPE_0:
164
165 return rthdr->ip6r_len * 8 / sizeof (struct in6_addr);
166 }
167
168 return -1;
169}
170
171
172/* RFC 3542, 7.6
173
174 This function returns a pointer to the IPv6 address specified by
175 index (which must have a value between 0 and one less than the
176 value returned by 'inet6_rth_segments') in the Routing header
177 described by BP. */
178struct in6_addr *
179inet6_rth_getaddr (const void *bp, int index)
180{
181 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
182
183 switch (rthdr->ip6r_type)
184 {
185 struct ip6_rthdr0 *rthdr0;
186 case IPV6_RTHDR_TYPE_0:
187 rthdr0 = (struct ip6_rthdr0 *) rthdr;
188
189 if (index >= rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr))
190 break;
191
192 return &rthdr0->ip6r0_addr[index];
193 }
194
195 return NULL;
196}
197