1/* Copyright (C) 2006-2023 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#include <string.h>
19#include <netinet/in.h>
20#include <netinet/ip6.h>
21
22
23/* RFC 3542, 7.1
24
25 This function returns the number of bytes required to hold a
26 Routing header of the specified type containing the specified
27 number of segments (addresses). For an IPv6 Type 0 Routing header,
28 the number of segments must be between 0 and 127, inclusive. */
29socklen_t
30inet6_rth_space (int type, int segments)
31{
32 switch (type)
33 {
34 case IPV6_RTHDR_TYPE_0:
35 if (segments < 0 || segments > 127)
36 return 0;
37
38 return sizeof (struct ip6_rthdr0) + segments * sizeof (struct in6_addr);
39 }
40
41 return 0;
42}
43
44
45/* RFC 3542, 7.2
46
47 This function initializes the buffer pointed to by BP to contain a
48 Routing header of the specified type and sets ip6r_len based on the
49 segments parameter. */
50void *
51inet6_rth_init (void *bp, socklen_t bp_len, int type, int segments)
52{
53 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
54
55 switch (type)
56 {
57 case IPV6_RTHDR_TYPE_0:
58 /* Make sure the parameters are valid and the buffer is large enough. */
59 if (segments < 0 || segments > 127)
60 break;
61
62 socklen_t len = (sizeof (struct ip6_rthdr0)
63 + segments * sizeof (struct in6_addr));
64 if (len > bp_len)
65 break;
66
67 /* Some implementations seem to initialize the whole memory area. */
68 memset (bp, '\0', len);
69
70 /* Length in units of 8 octets. */
71 rthdr->ip6r_len = segments * sizeof (struct in6_addr) / 8;
72 rthdr->ip6r_type = IPV6_RTHDR_TYPE_0;
73 return bp;
74 }
75
76 return NULL;
77}
78
79
80/* RFC 3542, 7.3
81
82 This function adds the IPv6 address pointed to by addr to the end of
83 the Routing header being constructed. */
84int
85inet6_rth_add (void *bp, const struct in6_addr *addr)
86{
87 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
88
89 switch (rthdr->ip6r_type)
90 {
91 struct ip6_rthdr0 *rthdr0;
92 case IPV6_RTHDR_TYPE_0:
93 rthdr0 = (struct ip6_rthdr0 *) rthdr;
94 if (rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr)
95 - rthdr0->ip6r0_segleft < 1)
96 return -1;
97
98 memcpy (&rthdr0->ip6r0_addr[rthdr0->ip6r0_segleft++],
99 addr, sizeof (struct in6_addr));
100
101 return 0;
102 }
103
104 return -1;
105}
106
107
108/* RFC 3542, 7.4
109
110 This function takes a Routing header extension header (pointed to by
111 the first argument) and writes a new Routing header that sends
112 datagrams along the reverse of that route. The function reverses the
113 order of the addresses and sets the segleft member in the new Routing
114 header to the number of segments. */
115int
116inet6_rth_reverse (const void *in, void *out)
117{
118 struct ip6_rthdr *in_rthdr = (struct ip6_rthdr *) in;
119
120 switch (in_rthdr->ip6r_type)
121 {
122 struct ip6_rthdr0 *in_rthdr0;
123 struct ip6_rthdr0 *out_rthdr0;
124 case IPV6_RTHDR_TYPE_0:
125 in_rthdr0 = (struct ip6_rthdr0 *) in;
126 out_rthdr0 = (struct ip6_rthdr0 *) out;
127
128 /* Copy header, not the addresses. The memory regions can overlap. */
129 memmove (out_rthdr0, in_rthdr0, sizeof (struct ip6_rthdr0));
130
131 int total = in_rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr);
132 for (int i = 0; i < total / 2; ++i)
133 {
134 /* Remember, IN_RTHDR0 and OUT_RTHDR0 might overlap. */
135 struct in6_addr temp = in_rthdr0->ip6r0_addr[i];
136 out_rthdr0->ip6r0_addr[i] = in_rthdr0->ip6r0_addr[total - 1 - i];
137 out_rthdr0->ip6r0_addr[total - 1 - i] = temp;
138 }
139 if (total % 2 != 0 && in != out)
140 out_rthdr0->ip6r0_addr[total / 2] = in_rthdr0->ip6r0_addr[total / 2];
141
142 out_rthdr0->ip6r0_segleft = total;
143
144 return 0;
145 }
146
147 return -1;
148}
149
150
151/* RFC 3542, 7.5
152
153 This function returns the number of segments (addresses) contained in
154 the Routing header described by BP. */
155int
156inet6_rth_segments (const void *bp)
157{
158 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
159
160 switch (rthdr->ip6r_type)
161 {
162 case IPV6_RTHDR_TYPE_0:
163
164 return rthdr->ip6r_len * 8 / sizeof (struct in6_addr);
165 }
166
167 return -1;
168}
169
170
171/* RFC 3542, 7.6
172
173 This function returns a pointer to the IPv6 address specified by
174 index (which must have a value between 0 and one less than the
175 value returned by 'inet6_rth_segments') in the Routing header
176 described by BP. */
177struct in6_addr *
178inet6_rth_getaddr (const void *bp, int index)
179{
180 struct ip6_rthdr *rthdr = (struct ip6_rthdr *) bp;
181
182 switch (rthdr->ip6r_type)
183 {
184 struct ip6_rthdr0 *rthdr0;
185 case IPV6_RTHDR_TYPE_0:
186 rthdr0 = (struct ip6_rthdr0 *) rthdr;
187
188 if (index >= rthdr0->ip6r0_len * 8 / sizeof (struct in6_addr))
189 break;
190
191 return &rthdr0->ip6r0_addr[index];
192 }
193
194 return NULL;
195}
196