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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. | |
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, write to the Free | |
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
18 | 02111-1307 USA. */ | |
19 | ||
20 | #include <assert.h> | |
21 | #include <string.h> | |
22 | #include <netinet/in.h> | |
23 | #include <netinet/ip6.h> | |
24 | #include <sys/param.h> | |
25 | ||
26 | ||
27 | static void | |
28 | internal_function | |
29 | add_pad (struct cmsghdr *cmsg, int len) | |
30 | { | |
31 | unsigned char *p = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0); | |
32 | ||
33 | if (len == 1) | |
34 | /* Special handling for 1, a one-byte solution. */ | |
35 | *p++ = IP6OPT_PAD1; | |
36 | else if (len != 0) | |
37 | { | |
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; | |
44 | } | |
45 | ||
46 | /* Account for the bytes. */ | |
47 | cmsg->cmsg_len += len; | |
48 | } | |
49 | ||
50 | ||
51 | static int | |
52 | get_opt_end (const uint8_t **result, const uint8_t *startp, | |
53 | const uint8_t *endp) | |
54 | { | |
55 | if (startp >= endp) | |
56 | /* Out of bounds. */ | |
57 | return -1; | |
58 | ||
59 | if (*startp == IP6OPT_PAD1) | |
60 | { | |
61 | /* Just this one byte. */ | |
62 | *result = startp + 1; | |
63 | return 0; | |
64 | } | |
65 | ||
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; | |
71 | ||
72 | *result = startp + startp[1] + 2; | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
77 | ||
78 | /* RFC 2292, 6.3.1 | |
79 | ||
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; | |
90 | { | |
91 | /* Add room for the extension header. */ | |
92 | nbytes += sizeof (struct ip6_ext); | |
93 | ||
94 | return CMSG_SPACE (roundup (nbytes, 8)); | |
95 | } | |
96 | ||
97 | ||
98 | /* RFC 2292, 6.3.2 | |
99 | ||
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. */ | |
103 | int | |
104 | inet6_option_init (bp, cmsgp, type) | |
105 | void *bp; | |
106 | struct cmsghdr **cmsgp; | |
107 | 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 | } | |
130 | ||
131 | ||
132 | /* RFC 2292, 6.3.3 | |
133 | ||
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. */ | |
138 | int | |
139 | inet6_option_append (cmsg, typep, multx, plusy) | |
140 | struct cmsghdr *cmsg; | |
141 | const uint8_t *typep; | |
142 | 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 = inet6_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 | } | |
163 | ||
164 | ||
165 | /* RFC 2292, 6.3.4 | |
166 | ||
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; | |
178 | { | |
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; | |
183 | ||
184 | /* Current data size. */ | |
185 | int dsize = cmsg->cmsg_len - CMSG_LEN (0); | |
186 | ||
187 | /* The first two bytes of the option are for the extended header. */ | |
188 | if (__builtin_expect (dsize == 0, 0)) | |
189 | { | |
190 | cmsg->cmsg_len += sizeof (struct ip6_ext); | |
191 | dsize = sizeof (struct ip6_ext); | |
192 | } | |
193 | ||
194 | /* First add padding. */ | |
195 | add_pad (cmsg, ((multx - (dsize & (multx - 1))) & (multx - 1)) + plusy); | |
196 | ||
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; | |
200 | ||
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)); | |
205 | ||
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; | |
212 | ||
213 | ((struct ip6_ext *) CMSG_DATA (cmsg))->ip6e_len = len8b; | |
214 | ||
215 | return result; | |
216 | } | |
217 | ||
218 | ||
219 | /* RFC 2292, 6.3.5 | |
220 | ||
221 | This function processes the next Hop-by-Hop option or Destination | |
222 | option in an ancillary data object. If another option remains to be | |
223 | processed, the return value of the function is 0 and *tptrp points to | |
224 | the 8-bit option type field (which is followed by the 8-bit option | |
225 | data length, followed by the option data). If no more options remain | |
226 | to be processed, the return value is -1 and *tptrp is NULL. If an | |
227 | error occurs, the return value is -1 and *tptrp is not NULL. */ | |
228 | int | |
229 | inet6_option_next (cmsg, tptrp) | |
230 | const struct cmsghdr *cmsg; | |
231 | uint8_t **tptrp; | |
232 | { | |
233 | /* Make sure it is an option of the right type. */ | |
234 | if (cmsg->cmsg_level != IPPROTO_IPV6 | |
235 | || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS)) | |
236 | return -1; | |
237 | ||
238 | /* Pointer to the extension header. We only compute the address, we | |
239 | don't access anything yet. */ | |
240 | const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg); | |
241 | ||
242 | /* Make sure the message is long enough. */ | |
243 | if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext)) | |
244 | /* Now we can access the extension header. */ | |
245 | || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8)) | |
246 | /* Too small. */ | |
247 | return -1; | |
248 | ||
249 | /* Determine the address of the byte past the message. */ | |
250 | const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8; | |
251 | ||
252 | const uint8_t *result; | |
253 | if (tptrp == NULL) | |
254 | /* This is the first call, return the first option if there is one. */ | |
255 | result = (const uint8_t *) (ip6e + 1); | |
256 | else | |
257 | { | |
258 | /* Make sure *TPTRP points to a beginning of a new option in | |
259 | the message. The upper limit is checked in get_opt_end. */ | |
260 | if (*tptrp < (const uint8_t *) (ip6e + 1)) | |
261 | return -1; | |
262 | ||
263 | /* Get the beginning of the next option. */ | |
264 | if (get_opt_end (&result, *tptrp, endp) != 0) | |
265 | return -1; | |
266 | } | |
267 | ||
268 | /* We know where the next option starts. */ | |
269 | *tptrp = (uint8_t *) result; | |
270 | ||
271 | /* Check the option is fully represented in the message. */ | |
272 | return get_opt_end (&result, result, endp); | |
273 | } | |
274 | ||
275 | ||
276 | /* RFC 2292, 6.3.6 | |
277 | ||
278 | This function is similar to the previously described | |
279 | inet6_option_next() function, except this function lets the caller | |
280 | specify the option type to be searched for, instead of always | |
281 | returning the next option in the ancillary data object. cmsg is a | |
282 | pointer to cmsghdr structure of which cmsg_level equals IPPROTO_IPV6 | |
283 | and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS. */ | |
284 | int | |
285 | inet6_option_find (cmsg, tptrp, type) | |
286 | const struct cmsghdr *cmsg; | |
287 | uint8_t **tptrp; | |
288 | int type; | |
289 | { | |
290 | /* Make sure it is an option of the right type. */ | |
291 | if (cmsg->cmsg_level != IPPROTO_IPV6 | |
292 | || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS)) | |
293 | return -1; | |
294 | ||
295 | /* Pointer to the extension header. We only compute the address, we | |
296 | don't access anything yet. */ | |
297 | const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg); | |
298 | ||
299 | /* Make sure the message is long enough. */ | |
300 | if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext)) | |
301 | /* Now we can access the extension header. */ | |
302 | || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8)) | |
303 | /* Too small. */ | |
304 | return -1; | |
305 | ||
306 | /* Determine the address of the byte past the message. */ | |
307 | const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8; | |
308 | ||
309 | const uint8_t *next; | |
310 | if (tptrp == NULL) | |
311 | /* This is the first call, return the first option if there is one. */ | |
312 | next = (const uint8_t *) (ip6e + 1); | |
313 | else | |
314 | { | |
315 | /* Make sure *TPTRP points to a beginning of a new option in | |
316 | the message. The upper limit is checked in get_opt_end. */ | |
317 | if (*tptrp < (const uint8_t *) (ip6e + 1)) | |
318 | return -1; | |
319 | ||
320 | /* Get the beginning of the next option. */ | |
321 | if (get_opt_end (&next, *tptrp, endp) != 0) | |
322 | return -1; | |
323 | } | |
324 | ||
325 | /* Now search for the appropriate typed entry. */ | |
326 | const uint8_t *result; | |
327 | do | |
328 | { | |
329 | result = next; | |
330 | ||
331 | /* Get the end of this entry. */ | |
332 | if (get_opt_end (&next, result, endp) != 0) | |
333 | return -1; | |
334 | } | |
335 | while (*result != type); | |
336 | ||
337 | /* We know where the next option starts. */ | |
338 | *tptrp = (uint8_t *) result; | |
339 | ||
340 | /* Success. */ | |
341 | return 0; | |
342 | } |