1/* Copyright (C) 2003-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
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 <assert.h>
20#include <string.h>
21#include <netinet/in.h>
22#include <netinet/ip6.h>
23#include <sys/param.h>
24
25
26static void
27add_pad (struct cmsghdr *cmsg, int len)
28{
29 unsigned char *p = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
30
31 if (len == 1)
32 /* Special handling for 1, a one-byte solution. */
33 *p++ = IP6OPT_PAD1;
34 else if (len != 0)
35 {
36 /* Multibyte padding. */
37 *p++ = IP6OPT_PADN;
38 *p++ = len - 2; /* Discount the two header bytes. */
39 /* The rest is filled with zero. */
40 memset (p, '\0', len - 2);
41 p += len - 2;
42 }
43
44 /* Account for the bytes. */
45 cmsg->cmsg_len += len;
46}
47
48
49static int
50get_opt_end (const uint8_t **result, const uint8_t *startp,
51 const uint8_t *endp)
52{
53 if (startp >= endp)
54 /* Out of bounds. */
55 return -1;
56
57 if (*startp == IP6OPT_PAD1)
58 {
59 /* Just this one byte. */
60 *result = startp + 1;
61 return 0;
62 }
63
64 /* Now we know there must be at least two bytes. */
65 if (startp + 2 > endp
66 /* Now we can get the length byte. */
67 || startp + startp[1] + 2 > endp)
68 return -1;
69
70 *result = startp + startp[1] + 2;
71
72 return 0;
73}
74
75
76static uint8_t *option_alloc (struct cmsghdr *cmsg, int datalen, int multx,
77 int plusy);
78
79
80/* RFC 2292, 6.3.1
81
82 This function returns the number of bytes required to hold an option
83 when it is stored as ancillary data, including the cmsghdr structure
84 at the beginning, and any padding at the end (to make its size a
85 multiple of 8 bytes). The argument is the size of the structure
86 defining the option, which must include any pad bytes at the
87 beginning (the value y in the alignment term "xn + y"), the type
88 byte, the length byte, and the option data. */
89int
90inet6_option_space (int nbytes)
91{
92 /* Add room for the extension header. */
93 nbytes += sizeof (struct ip6_ext);
94
95 return CMSG_SPACE (roundup (nbytes, 8));
96}
97link_warning (inet6_option_space,
98 "inet6_option_space is obsolete, use the RFC 3542 interfaces")
99
100
101/* RFC 2292, 6.3.2
102
103 This function is called once per ancillary data object that will
104 contain either Hop-by-Hop or Destination options. It returns 0 on
105 success or -1 on an error. */
106int
107inet6_option_init (void *bp, struct cmsghdr **cmsgp, int type)
108{
109 /* Only Hop-by-Hop or Destination options allowed. */
110 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
111 return -1;
112
113 /* BP is a pointer to the previously allocated space. */
114 struct cmsghdr *newp = (struct cmsghdr *) bp;
115
116 /* Initialize the message header.
117
118 Length: No data yet, only the cmsghdr struct. */
119 newp->cmsg_len = CMSG_LEN (0);
120 /* Originating protocol: obviously IPv6. */
121 newp->cmsg_level = IPPROTO_IPV6;
122 /* Message type. */
123 newp->cmsg_type = type;
124
125 /* Pass up the result. */
126 *cmsgp = newp;
127
128 return 0;
129}
130link_warning (inet6_option_init,
131 "inet6_option_init is obsolete, use the RFC 3542 interfaces")
132
133
134/* RFC 2292, 6.3.3
135
136 This function appends a Hop-by-Hop option or a Destination option
137 into an ancillary data object that has been initialized by
138 inet6_option_init(). This function returns 0 if it succeeds or -1 on
139 an error. */
140int
141inet6_option_append (struct cmsghdr *cmsg, const uint8_t *typep, int multx,
142 int plusy)
143{
144 /* typep is a pointer to the 8-bit option type. It is assumed that this
145 field is immediately followed by the 8-bit option data length field,
146 which is then followed immediately by the option data.
147
148 The option types IP6OPT_PAD1 and IP6OPT_PADN also must be handled. */
149 int len = typep[0] == IP6OPT_PAD1 ? 1 : typep[1] + 2;
150
151 /* Get the pointer to the space in the message. */
152 uint8_t *ptr = option_alloc (cmsg, len, multx, plusy);
153 if (ptr == NULL)
154 /* Some problem with the parameters. */
155 return -1;
156
157 /* Copy the content. */
158 memcpy (ptr, typep, len);
159
160 return 0;
161}
162link_warning (inet6_option_append,
163 "inet6_option_append is obsolete, use the RFC 3542 interfaces")
164
165
166/* RFC 2292, 6.3.4
167
168 This function appends a Hop-by-Hop option or a Destination option
169 into an ancillary data object that has been initialized by
170 inet6_option_init(). This function returns a pointer to the 8-bit
171 option type field that starts the option on success, or NULL on an
172 error. */
173static uint8_t *
174option_alloc (struct cmsghdr *cmsg, int datalen, int multx, int plusy)
175{
176 /* The RFC limits the value of the alignment values. */
177 if ((multx != 1 && multx != 2 && multx != 4 && multx != 8)
178 || ! (plusy >= 0 && plusy <= 7))
179 return NULL;
180
181 /* Current data size. */
182 int dsize = cmsg->cmsg_len - CMSG_LEN (0);
183
184 /* The first two bytes of the option are for the extended header. */
185 if (__glibc_unlikely (dsize == 0))
186 {
187 cmsg->cmsg_len += sizeof (struct ip6_ext);
188 dsize = sizeof (struct ip6_ext);
189 }
190
191 /* First add padding. */
192 add_pad (cmsg, ((multx - (dsize & (multx - 1))) & (multx - 1)) + plusy);
193
194 /* Return the pointer to the start of the option space. */
195 uint8_t *result = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
196 cmsg->cmsg_len += datalen;
197
198 /* The extended option header length is measured in 8-byte groups.
199 To represent the current length we might have to add padding. */
200 dsize = cmsg->cmsg_len - CMSG_LEN (0);
201 add_pad (cmsg, (8 - (dsize & (8 - 1))) & (8 - 1));
202
203 /* Record the new length of the option. */
204 assert (((cmsg->cmsg_len - CMSG_LEN (0)) % 8) == 0);
205 int len8b = (cmsg->cmsg_len - CMSG_LEN (0)) / 8 - 1;
206 if (len8b >= 256)
207 /* Too long. */
208 return NULL;
209
210 struct ip6_ext *ie = (void *) CMSG_DATA (cmsg);
211 ie->ip6e_len = len8b;
212
213 return result;
214}
215
216
217uint8_t *
218inet6_option_alloc (struct cmsghdr *cmsg, int datalen, int multx, int plusy)
219{
220 return option_alloc (cmsg, datalen, multx, plusy);
221}
222link_warning (inet6_option_alloc,
223 "inet6_option_alloc is obsolete, use the RFC 3542 interfaces")
224
225
226/* RFC 2292, 6.3.5
227
228 This function processes the next Hop-by-Hop option or Destination
229 option in an ancillary data object. If another option remains to be
230 processed, the return value of the function is 0 and *tptrp points to
231 the 8-bit option type field (which is followed by the 8-bit option
232 data length, followed by the option data). If no more options remain
233 to be processed, the return value is -1 and *tptrp is NULL. If an
234 error occurs, the return value is -1 and *tptrp is not NULL. */
235int
236inet6_option_next (const struct cmsghdr *cmsg, uint8_t **tptrp)
237{
238 /* Make sure it is an option of the right type. */
239 if (cmsg->cmsg_level != IPPROTO_IPV6
240 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
241 return -1;
242
243 /* Pointer to the extension header. We only compute the address, we
244 don't access anything yet. */
245 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
246
247 /* Make sure the message is long enough. */
248 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
249 /* Now we can access the extension header. */
250 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
251 /* Too small. */
252 return -1;
253
254 /* Determine the address of the byte past the message. */
255 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
256
257 const uint8_t *result;
258 if (*tptrp == NULL)
259 /* This is the first call, return the first option if there is one. */
260 result = (const uint8_t *) (ip6e + 1);
261 else
262 {
263 /* Make sure *TPTRP points to a beginning of a new option in
264 the message. The upper limit is checked in get_opt_end. */
265 if (*tptrp < (const uint8_t *) (ip6e + 1))
266 return -1;
267
268 /* Get the beginning of the next option. */
269 if (get_opt_end (&result, *tptrp, endp) != 0)
270 return -1;
271 }
272
273 /* We know where the next option starts. */
274 *tptrp = (uint8_t *) result;
275
276 /* Check the option is fully represented in the message. */
277 return get_opt_end (&result, result, endp);
278}
279link_warning (inet6_option_next,
280 "inet6_option_next is obsolete, use the RFC 3542 interfaces")
281
282
283/* RFC 2292, 6.3.6
284
285 This function is similar to the previously described
286 inet6_option_next() function, except this function lets the caller
287 specify the option type to be searched for, instead of always
288 returning the next option in the ancillary data object. cmsg is a
289 pointer to cmsghdr structure of which cmsg_level equals IPPROTO_IPV6
290 and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS. */
291int
292inet6_option_find (const struct cmsghdr *cmsg, uint8_t **tptrp, int type)
293{
294 /* Make sure it is an option of the right type. */
295 if (cmsg->cmsg_level != IPPROTO_IPV6
296 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
297 return -1;
298
299 /* Pointer to the extension header. We only compute the address, we
300 don't access anything yet. */
301 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
302
303 /* Make sure the message is long enough. */
304 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
305 /* Now we can access the extension header. */
306 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
307 /* Too small. */
308 return -1;
309
310 /* Determine the address of the byte past the message. */
311 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
312
313 const uint8_t *next;
314 if (*tptrp == NULL)
315 /* This is the first call, return the first option if there is one. */
316 next = (const uint8_t *) (ip6e + 1);
317 else
318 {
319 /* Make sure *TPTRP points to a beginning of a new option in
320 the message. The upper limit is checked in get_opt_end. */
321 if (*tptrp < (const uint8_t *) (ip6e + 1))
322 return -1;
323
324 /* Get the beginning of the next option. */
325 if (get_opt_end (&next, *tptrp, endp) != 0)
326 return -1;
327 }
328
329 /* Now search for the appropriate typed entry. */
330 const uint8_t *result;
331 do
332 {
333 result = next;
334
335 /* Get the end of this entry. */
336 if (get_opt_end (&next, result, endp) != 0)
337 return -1;
338 }
339 while (*result != type);
340
341 /* We know where the next option starts. */
342 *tptrp = (uint8_t *) result;
343
344 /* Success. */
345 return 0;
346}
347link_warning (inet6_option_find,
348 "inet6_option_find is obsolete, use the RFC 3542 interfaces")
349