Update.
[glibc.git] / inet / inet6_option.c
blob2e0fed8a30c29d7ebf99a11d0076fcf1e39ca3c8
1 /* Copyright (C) 2003 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
20 #include <assert.h>
21 #include <string.h>
22 #include <netinet/in.h>
23 #include <netinet/ip6.h>
24 #include <sys/param.h>
27 static void
28 internal_function
29 add_pad (struct cmsghdr *cmsg, int len)
31 unsigned char *p = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
33 if (len == 1)
34 /* Special handling for 1, a one-byte solution. */
35 *p++ = IP6OPT_PAD1;
36 else if (len != 0)
38 /* Multibyte padding. */
39 *p++ = IP6OPT_PADN;
40 *p++ = len - 2; /* Discount the two header bytes. */
41 /* The rest is filled with zero. */
42 memset (p, '\0', len - 2);
43 p += len - 2;
46 /* Account for the bytes. */
47 cmsg->cmsg_len += len;
51 static int
52 get_opt_end (const uint8_t **result, const uint8_t *startp,
53 const uint8_t *endp)
55 if (startp >= endp)
56 /* Out of bounds. */
57 return -1;
59 if (*startp == IP6OPT_PAD1)
61 /* Just this one byte. */
62 *result = startp + 1;
63 return 0;
66 /* Now we know there must be at least two bytes. */
67 if (startp + 2 > endp
68 /* Now we can get the length byte. */
69 || startp + startp[1] + 2 > endp)
70 return -1;
72 *result = startp + startp[1] + 2;
74 return 0;
78 /* RFC 2292, 6.3.1
80 This function returns the number of bytes required to hold an option
81 when it is stored as ancillary data, including the cmsghdr structure
82 at the beginning, and any padding at the end (to make its size a
83 multiple of 8 bytes). The argument is the size of the structure
84 defining the option, which must include any pad bytes at the
85 beginning (the value y in the alignment term "xn + y"), the type
86 byte, the length byte, and the option data. */
87 int
88 inet6_option_space (nbytes)
89 int nbytes;
91 /* Add room for the extension header. */
92 nbytes += sizeof (struct ip6_ext);
94 return CMSG_SPACE (roundup (nbytes, 8));
98 /* RFC 2292, 6.3.2
100 This function is called once per ancillary data object that will
101 contain either Hop-by-Hop or Destination options. It returns 0 on
102 success or -1 on an error. */
104 inet6_option_init (bp, cmsgp, type)
105 void *bp;
106 struct cmsghdr **cmsgp;
107 int type;
109 /* Only Hop-by-Hop or Destination options allowed. */
110 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
111 return -1;
113 /* BP is a pointer to the previously allocated space. */
114 struct cmsghdr *newp = (struct cmsghdr *) bp;
116 /* Initialize the message header.
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;
125 /* Pass up the result. */
126 *cmsgp = newp;
128 return 0;
132 /* RFC 2292, 6.3.3
134 This function appends a Hop-by-Hop option or a Destination option
135 into an ancillary data object that has been initialized by
136 inet6_option_init(). This function returns 0 if it succeeds or -1 on
137 an error. */
139 inet6_option_append (cmsg, typep, multx, plusy)
140 struct cmsghdr *cmsg;
141 const uint8_t *typep;
142 int multx;
143 int plusy;
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.
149 The option types IP6OPT_PAD1 and IP6OPT_PADN also must be handled. */
150 int len = typep[0] == IP6OPT_PAD1 ? 1 : typep[1] + 2;
152 /* Get the pointer to the space in the message. */
153 uint8_t *ptr = inet6_option_alloc (cmsg, len, multx, plusy);
154 if (ptr == NULL)
155 /* Some problem with the parameters. */
156 return -1;
158 /* Copy the content. */
159 memcpy (ptr, typep, len);
161 return 0;
165 /* RFC 2292, 6.3.4
167 This function appends a Hop-by-Hop option or a Destination option
168 into an ancillary data object that has been initialized by
169 inet6_option_init(). This function returns a pointer to the 8-bit
170 option type field that starts the option on success, or NULL on an
171 error. */
172 uint8_t *
173 inet6_option_alloc (cmsg, datalen, multx, plusy)
174 struct cmsghdr *cmsg;
175 int datalen;
176 int multx;
177 int plusy;
179 /* The RFC limits the value of the alignment values. */
180 if ((multx != 1 && multx != 2 && multx != 4 && multx != 8)
181 || ! (plusy >= 0 && plusy <= 7))
182 return NULL;
184 /* Current data size. */
185 int dsize = cmsg->cmsg_len - CMSG_LEN (0);
187 /* The first two bytes of the option are for the extended header. */
188 if (__builtin_expect (dsize == 0, 0))
190 cmsg->cmsg_len += sizeof (struct ip6_ext);
191 dsize = sizeof (struct ip6_ext);
194 /* First add padding. */
195 add_pad (cmsg, ((multx - (dsize & (multx - 1))) & (multx - 1)) + plusy);
197 /* Return the pointer to the start of the option space. */
198 uint8_t *result = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0);
199 cmsg->cmsg_len += datalen;
201 /* The extended option header length is measured in 8-byte groups.
202 To represent the current length we might have to add padding. */
203 dsize = cmsg->cmsg_len - CMSG_LEN (0);
204 add_pad (cmsg, (8 - (dsize & (8 - 1))) & (8 - 1));
206 /* Record the new length of the option. */
207 assert (((cmsg->cmsg_len - CMSG_LEN (0)) % 8) == 0);
208 int len8b = (cmsg->cmsg_len - CMSG_LEN (0)) / 8 - 1;
209 if (len8b >= 256)
210 /* Too long. */
211 return NULL;
213 ((struct ip6_ext *) CMSG_DATA (cmsg))->ip6e_len = len8b;
215 return result;
217 libc_hidden_def (inet6_option_alloc)
220 /* RFC 2292, 6.3.5
222 This function processes the next Hop-by-Hop option or Destination
223 option in an ancillary data object. If another option remains to be
224 processed, the return value of the function is 0 and *tptrp points to
225 the 8-bit option type field (which is followed by the 8-bit option
226 data length, followed by the option data). If no more options remain
227 to be processed, the return value is -1 and *tptrp is NULL. If an
228 error occurs, the return value is -1 and *tptrp is not NULL. */
230 inet6_option_next (cmsg, tptrp)
231 const struct cmsghdr *cmsg;
232 uint8_t **tptrp;
234 /* Make sure it is an option of the right type. */
235 if (cmsg->cmsg_level != IPPROTO_IPV6
236 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
237 return -1;
239 /* Pointer to the extension header. We only compute the address, we
240 don't access anything yet. */
241 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
243 /* Make sure the message is long enough. */
244 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
245 /* Now we can access the extension header. */
246 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
247 /* Too small. */
248 return -1;
250 /* Determine the address of the byte past the message. */
251 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
253 const uint8_t *result;
254 if (tptrp == NULL)
255 /* This is the first call, return the first option if there is one. */
256 result = (const uint8_t *) (ip6e + 1);
257 else
259 /* Make sure *TPTRP points to a beginning of a new option in
260 the message. The upper limit is checked in get_opt_end. */
261 if (*tptrp < (const uint8_t *) (ip6e + 1))
262 return -1;
264 /* Get the beginning of the next option. */
265 if (get_opt_end (&result, *tptrp, endp) != 0)
266 return -1;
269 /* We know where the next option starts. */
270 *tptrp = (uint8_t *) result;
272 /* Check the option is fully represented in the message. */
273 return get_opt_end (&result, result, endp);
277 /* RFC 2292, 6.3.6
279 This function is similar to the previously described
280 inet6_option_next() function, except this function lets the caller
281 specify the option type to be searched for, instead of always
282 returning the next option in the ancillary data object. cmsg is a
283 pointer to cmsghdr structure of which cmsg_level equals IPPROTO_IPV6
284 and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS. */
286 inet6_option_find (cmsg, tptrp, type)
287 const struct cmsghdr *cmsg;
288 uint8_t **tptrp;
289 int type;
291 /* Make sure it is an option of the right type. */
292 if (cmsg->cmsg_level != IPPROTO_IPV6
293 || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS))
294 return -1;
296 /* Pointer to the extension header. We only compute the address, we
297 don't access anything yet. */
298 const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg);
300 /* Make sure the message is long enough. */
301 if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext))
302 /* Now we can access the extension header. */
303 || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8))
304 /* Too small. */
305 return -1;
307 /* Determine the address of the byte past the message. */
308 const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8;
310 const uint8_t *next;
311 if (tptrp == NULL)
312 /* This is the first call, return the first option if there is one. */
313 next = (const uint8_t *) (ip6e + 1);
314 else
316 /* Make sure *TPTRP points to a beginning of a new option in
317 the message. The upper limit is checked in get_opt_end. */
318 if (*tptrp < (const uint8_t *) (ip6e + 1))
319 return -1;
321 /* Get the beginning of the next option. */
322 if (get_opt_end (&next, *tptrp, endp) != 0)
323 return -1;
326 /* Now search for the appropriate typed entry. */
327 const uint8_t *result;
330 result = next;
332 /* Get the end of this entry. */
333 if (get_opt_end (&next, result, endp) != 0)
334 return -1;
336 while (*result != type);
338 /* We know where the next option starts. */
339 *tptrp = (uint8_t *) result;
341 /* Success. */
342 return 0;