1/* Copyright (C) 2003-2016 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 <http://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
27internal_function
28add_pad (struct cmsghdr *cmsg, int len)
29{
30 unsigned char *p = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
31
32 if (len == 1)
33 /* Special handling for 1, a one-byte solution. */
34 *p++ = IP6OPT_PAD1;
35 else if (len != 0)
36 {
37 /* Multibyte padding. */
38 *p++ = IP6OPT_PADN;
39 *p++ = len - 2; /* Discount the two header bytes. */
40 /* The rest is filled with zero. */
41 memset (p, '\0', len - 2);
42 p += len - 2;
43 }
44
45 /* Account for the bytes. */
46 cmsg->cmsg_len += len;
47}
48
49
50static int
51get_opt_end (const uint8_t **result, const uint8_t *startp,
52 const uint8_t *endp)
53{
54 if (startp >= endp)
55 /* Out of bounds. */
56 return -1;
57
58 if (*startp == IP6OPT_PAD1)
59 {
60 /* Just this one byte. */
61 *result = startp + 1;
62 return 0;
63 }
64
65 /* Now we know there must be at least two bytes. */
66 if (startp + 2 > endp
67 /* Now we can get the length byte. */
68 || startp + startp[1] + 2 > endp)
69 return -1;
70
71 *result = startp + startp[1] + 2;
72
73 return 0;
74}
75
76
77static uint8_t *option_alloc (struct cmsghdr *cmsg, int datalen, int multx,
78 int plusy);
79
80
81/* RFC 2292, 6.3.1
82
83 This function returns the number of bytes required to hold an option
84 when it is stored as ancillary data, including the cmsghdr structure
85 at the beginning, and any padding at the end (to make its size a
86 multiple of 8 bytes). The argument is the size of the structure
87 defining the option, which must include any pad bytes at the
88 beginning (the value y in the alignment term "xn + y"), the type
89 byte, the length byte, and the option data. */
90int
91inet6_option_space (int nbytes)
92{
93 /* Add room for the extension header. */
94 nbytes += sizeof (struct ip6_ext);
95
96 return CMSG_SPACE (roundup (nbytes, 8));
97}
98link_warning (inet6_option_space,
99 "inet6_option_space is obsolete, use the RFC 3542 interfaces")
100
101
102/* RFC 2292, 6.3.2
103
104 This function is called once per ancillary data object that will
105 contain either Hop-by-Hop or Destination options. It returns 0 on
106 success or -1 on an error. */
107int
108inet6_option_init (void *bp, struct cmsghdr **cmsgp, int type)
109{
110 /* Only Hop-by-Hop or Destination options allowed. */
111 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
112 return -1;
113
114 /* BP is a pointer to the previously allocated space. */
115 struct cmsghdr *newp = (struct cmsghdr *) bp;
116
117 /* Initialize the message header.
118
119 Length: No data yet, only the cmsghdr struct. */
120 newp->cmsg_len = CMSG_LEN (0);
121 /* Originating protocol: obviously IPv6. */
122 newp->cmsg_level = IPPROTO_IPV6;
123 /* Message type. */
124 newp->cmsg_type = type;
125
126 /* Pass up the result. */
127 *cmsgp = newp;
128
129 return 0;
130}
131link_warning (inet6_option_init,
132 "inet6_option_init is obsolete, use the RFC 3542 interfaces")
133
134
135/* RFC 2292, 6.3.3
136
137 This function appends a Hop-by-Hop option or a Destination option
138 into an ancillary data object that has been initialized by
139 inet6_option_init(). This function returns 0 if it succeeds or -1 on
140 an error. */
141int
142inet6_option_append (struct cmsghdr *cmsg, const uint8_t *typep, int multx,
143 int plusy)
144{
145 /* typep is a pointer to the 8-bit option type. It is assumed that this
146 field is immediately followed by the 8-bit option data length field,
147 which is then followed immediately by the option data.
148
149 The option types IP6OPT_PAD1 and IP6OPT_PADN also must be handled. */
150 int len = typep[0] == IP6OPT_PAD1 ? 1 : typep[1] + 2;
151
152 /* Get the pointer to the space in the message. */
153 uint8_t *ptr = option_alloc (cmsg, len, multx, plusy);
154 if (ptr == NULL)
155 /* Some problem with the parameters. */
156 return -1;
157
158 /* Copy the content. */
159 memcpy (ptr, typep, len);
160
161 return 0;
162}
163link_warning (inet6_option_append,
164 "inet6_option_append is obsolete, use the RFC 3542 interfaces")
165
166
167/* RFC 2292, 6.3.4
168
169 This function appends a Hop-by-Hop option or a Destination option
170 into an ancillary data object that has been initialized by
171 inet6_option_init(). This function returns a pointer to the 8-bit
172 option type field that starts the option on success, or NULL on an
173 error. */
174static uint8_t *
175option_alloc (struct cmsghdr *cmsg, int datalen, int multx, int plusy)
176{
177 /* The RFC limits the value of the alignment values. */
178 if ((multx != 1 && multx != 2 && multx != 4 && multx != 8)
179 || ! (plusy >= 0 && plusy <= 7))
180 return NULL;
181
182 /* Current data size. */
183 int dsize = cmsg->cmsg_len - CMSG_LEN (0);
184
185 /* The first two bytes of the option are for the extended header. */
186 if (__glibc_unlikely (dsize == 0))
187 {
188 cmsg->cmsg_len += sizeof (struct ip6_ext);
189 dsize = sizeof (struct ip6_ext);
190 }
191
192 /* First add padding. */
193 add_pad (cmsg, ((multx - (dsize & (multx - 1))) & (multx - 1)) + plusy);
194
195 /* Return the pointer to the start of the option space. */
196 uint8_t *result = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
197 cmsg->cmsg_len += datalen;
198
199 /* The extended option header length is measured in 8-byte groups.
200 To represent the current length we might have to add padding. */
201 dsize = cmsg->cmsg_len - CMSG_LEN (0);
202 add_pad (cmsg, (8 - (dsize & (8 - 1))) & (8 - 1));
203
204 /* Record the new length of the option. */
205 assert (((cmsg->cmsg_len - CMSG_LEN (0)) % 8) == 0);
206 int len8b = (cmsg->cmsg_len - CMSG_LEN (0)) / 8 - 1;
207 if (len8b >= 256)
208 /* Too long. */
209 return NULL;
210
211 struct ip6_ext *ie = (void *) CMSG_DATA (cmsg);
212 ie->ip6e_len = len8b;
213
214 return result;
215}
216
217
218uint8_t *
219inet6_option_alloc (struct cmsghdr *cmsg, int datalen, int multx, int plusy)
220{
221 return option_alloc (cmsg, datalen, multx, plusy);
222}
223link_warning (inet6_option_alloc,
224 "inet6_option_alloc is obsolete, use the RFC 3542 interfaces")
225
226
227/* RFC 2292, 6.3.5
228
229 This function processes the next Hop-by-Hop option or Destination
230 option in an ancillary data object. If another option remains to be
231 processed, the return value of the function is 0 and *tptrp points to
232 the 8-bit option type field (which is followed by the 8-bit option
233 data length, followed by the option data). If no more options remain
234 to be processed, the return value is -1 and *tptrp is NULL. If an
235 error occurs, the return value is -1 and *tptrp is not NULL. */
236int
237inet6_option_next (const struct cmsghdr *cmsg, uint8_t **tptrp)
238{
239 /* Make sure it is an option of the right type. */
240 if (cmsg->cmsg_level != IPPROTO_IPV6
241 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
242 return -1;
243
244 /* Pointer to the extension header. We only compute the address, we
245 don't access anything yet. */
246 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
247
248 /* Make sure the message is long enough. */
249 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
250 /* Now we can access the extension header. */
251 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
252 /* Too small. */
253 return -1;
254
255 /* Determine the address of the byte past the message. */
256 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
257
258 const uint8_t *result;
259 if (*tptrp == NULL)
260 /* This is the first call, return the first option if there is one. */
261 result = (const uint8_t *) (ip6e + 1);
262 else
263 {
264 /* Make sure *TPTRP points to a beginning of a new option in
265 the message. The upper limit is checked in get_opt_end. */
266 if (*tptrp < (const uint8_t *) (ip6e + 1))
267 return -1;
268
269 /* Get the beginning of the next option. */
270 if (get_opt_end (&result, *tptrp, endp) != 0)
271 return -1;
272 }
273
274 /* We know where the next option starts. */
275 *tptrp = (uint8_t *) result;
276
277 /* Check the option is fully represented in the message. */
278 return get_opt_end (&result, result, endp);
279}
280link_warning (inet6_option_next,
281 "inet6_option_next is obsolete, use the RFC 3542 interfaces")
282
283
284/* RFC 2292, 6.3.6
285
286 This function is similar to the previously described
287 inet6_option_next() function, except this function lets the caller
288 specify the option type to be searched for, instead of always
289 returning the next option in the ancillary data object. cmsg is a
290 pointer to cmsghdr structure of which cmsg_level equals IPPROTO_IPV6
291 and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS. */
292int
293inet6_option_find (const struct cmsghdr *cmsg, uint8_t **tptrp, int type)
294{
295 /* Make sure it is an option of the right type. */
296 if (cmsg->cmsg_level != IPPROTO_IPV6
297 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
298 return -1;
299
300 /* Pointer to the extension header. We only compute the address, we
301 don't access anything yet. */
302 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
303
304 /* Make sure the message is long enough. */
305 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
306 /* Now we can access the extension header. */
307 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
308 /* Too small. */
309 return -1;
310
311 /* Determine the address of the byte past the message. */
312 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
313
314 const uint8_t *next;
315 if (*tptrp == NULL)
316 /* This is the first call, return the first option if there is one. */
317 next = (const uint8_t *) (ip6e + 1);
318 else
319 {
320 /* Make sure *TPTRP points to a beginning of a new option in
321 the message. The upper limit is checked in get_opt_end. */
322 if (*tptrp < (const uint8_t *) (ip6e + 1))
323 return -1;
324
325 /* Get the beginning of the next option. */
326 if (get_opt_end (&next, *tptrp, endp) != 0)
327 return -1;
328 }
329
330 /* Now search for the appropriate typed entry. */
331 const uint8_t *result;
332 do
333 {
334 result = next;
335
336 /* Get the end of this entry. */
337 if (get_opt_end (&next, result, endp) != 0)
338 return -1;
339 }
340 while (*result != type);
341
342 /* We know where the next option starts. */
343 *tptrp = (uint8_t *) result;
344
345 /* Success. */
346 return 0;
347}
348link_warning (inet6_option_find,
349 "inet6_option_find is obsolete, use the RFC 3542 interfaces")
350