ip6opt.c revision 1.1
1 /* 2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the project nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/types.h> 32 #include <sys/socket.h> 33 34 #include <netinet/in.h> 35 #include <netinet/ip6.h> 36 37 #include <string.h> 38 #include <stdio.h> 39 40 static int ip6optlen(u_int8_t *opt, u_int8_t *lim); 41 static void inet6_insert_padopt(u_char *p, int len); 42 43 /* 44 * This function returns the number of bytes required to hold an option 45 * when it is stored as ancillary data, including the cmsghdr structure 46 * at the beginning, and any padding at the end (to make its size a 47 * multiple of 8 bytes). The argument is the size of the structure 48 * defining the option, which must include any pad bytes at the 49 * beginning (the value y in the alignment term "xn + y"), the type 50 * byte, the length byte, and the option data. 51 */ 52 int 53 inet6_option_space(nbytes) 54 int nbytes; 55 { 56 nbytes += 2; /* we need space for nxt-hdr and length fields */ 57 return(CMSG_SPACE((nbytes + 7) & ~7)); 58 } 59 60 /* 61 * This function is called once per ancillary data object that will 62 * contain either Hop-by-Hop or Destination options. It returns 0 on 63 * success or -1 on an error. 64 */ 65 int 66 inet6_option_init(bp, cmsgp, type) 67 void *bp; 68 struct cmsghdr **cmsgp; 69 int type; 70 { 71 register struct cmsghdr *ch = (struct cmsghdr *)bp; 72 73 /* argument validation */ 74 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) 75 return(-1); 76 77 ch->cmsg_level = IPPROTO_IPV6; 78 ch->cmsg_type = type; 79 ch->cmsg_len = CMSG_LEN(0); 80 81 *cmsgp = ch; 82 return(0); 83 } 84 85 /* 86 * This function appends a Hop-by-Hop option or a Destination option 87 * into an ancillary data object that has been initialized by 88 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 89 * an error. 90 * multx is the value x in the alignment term "xn + y" described 91 * earlier. It must have a value of 1, 2, 4, or 8. 92 * plusy is the value y in the alignment term "xn + y" described 93 * earlier. It must have a value between 0 and 7, inclusive. 94 */ 95 int 96 inet6_option_append(cmsg, typep, multx, plusy) 97 struct cmsghdr *cmsg; 98 const u_int8_t *typep; 99 int multx; 100 int plusy; 101 { 102 int padlen, optlen, off; 103 register u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 104 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 105 106 /* argument validation */ 107 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 108 return(-1); 109 if (plusy < 0 || plusy > 7) 110 return(-1); 111 if (typep[0] > 255) 112 return(-1); 113 114 /* 115 * If this is the first option, allocate space for the 116 * first 2 bytes(for next header and length fields) of 117 * the option header. 118 */ 119 if (bp == (u_char *)eh) { 120 bp += 2; 121 cmsg->cmsg_len += 2; 122 } 123 124 /* calculate pad length before the option. */ 125 off = bp - (u_char *)eh; 126 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 127 (off % multx); 128 padlen += plusy; 129 /* insert padding */ 130 inet6_insert_padopt(bp, padlen); 131 cmsg->cmsg_len += padlen; 132 bp += padlen; 133 134 /* copy the option */ 135 if (typep[0] == IP6OPT_PAD1) 136 optlen = 1; 137 else 138 optlen = typep[1] + 2; 139 memcpy(bp, typep, optlen); 140 bp += optlen; 141 cmsg->cmsg_len += optlen; 142 143 /* calculate pad length after the option and insert the padding */ 144 off = bp - (u_char *)eh; 145 padlen = ((off + 7) & ~7) - off; 146 inet6_insert_padopt(bp, padlen); 147 bp += padlen; 148 cmsg->cmsg_len += padlen; 149 150 /* update the length field of the ip6 option header */ 151 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 152 153 return(0); 154 } 155 156 /* 157 * This function appends a Hop-by-Hop option or a Destination option 158 * into an ancillary data object that has been initialized by 159 * inet6_option_init(). This function returns a pointer to the 8-bit 160 * option type field that starts the option on success, or NULL on an 161 * error. 162 * The difference between this function and inet6_option_append() is 163 * that the latter copies the contents of a previously built option into 164 * the ancillary data object while the current function returns a 165 * pointer to the space in the data object where the option's TLV must 166 * then be built by the caller. 167 * 168 */ 169 u_int8_t * 170 inet6_option_alloc(cmsg, datalen, multx, plusy) 171 struct cmsghdr *cmsg; 172 int datalen; 173 int multx; 174 int plusy; 175 { 176 int padlen, off; 177 register u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 178 u_int8_t *retval; 179 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 180 181 /* argument validation */ 182 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 183 return(NULL); 184 if (plusy < 0 || plusy > 7) 185 return(NULL); 186 187 /* 188 * If this is the first option, allocate space for the 189 * first 2 bytes(for next header and length fields) of 190 * the option header. 191 */ 192 if (bp == (u_char *)eh) { 193 bp += 2; 194 cmsg->cmsg_len += 2; 195 } 196 197 /* calculate pad length before the option. */ 198 off = bp - (u_char *)eh; 199 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 200 (off % multx); 201 padlen += plusy; 202 /* insert padding */ 203 inet6_insert_padopt(bp, padlen); 204 cmsg->cmsg_len += padlen; 205 bp += padlen; 206 207 /* keep space to store specified length of data */ 208 retval = bp; 209 bp += datalen; 210 cmsg->cmsg_len += datalen; 211 212 /* calculate pad length after the option and insert the padding */ 213 off = bp - (u_char *)eh; 214 padlen = ((off + 7) & ~7) - off; 215 inet6_insert_padopt(bp, padlen); 216 bp += padlen; 217 cmsg->cmsg_len += padlen; 218 219 /* update the length field of the ip6 option header */ 220 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 221 222 return(retval); 223 } 224 225 /* 226 * This function processes the next Hop-by-Hop option or Destination 227 * option in an ancillary data object. If another option remains to be 228 * processed, the return value of the function is 0 and *tptrp points to 229 * the 8-bit option type field (which is followed by the 8-bit option 230 * data length, followed by the option data). If no more options remain 231 * to be processed, the return value is -1 and *tptrp is NULL. If an 232 * error occurs, the return value is -1 and *tptrp is not NULL. 233 * (RFC 2292, 6.3.5) 234 */ 235 int 236 inet6_option_next(cmsg, tptrp) 237 const struct cmsghdr *cmsg; 238 u_int8_t **tptrp; 239 { 240 struct ip6_ext *ip6e; 241 int hdrlen, optlen; 242 u_int8_t *lim; 243 244 if (cmsg->cmsg_level != IPPROTO_IPV6 || 245 (cmsg->cmsg_type != IPV6_HOPOPTS && 246 cmsg->cmsg_type != IPV6_DSTOPTS)) 247 return(-1); 248 249 /* message length validation */ 250 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 251 return(-1); 252 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 253 hdrlen = (ip6e->ip6e_len + 1) << 3; 254 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 255 return(-1); 256 257 /* 258 * If the caller does not specify the starting point, 259 * simply return the 1st option. 260 * Otherwise, search the option list for the next option. 261 */ 262 lim = (u_int8_t *)ip6e + hdrlen; 263 if (*tptrp == NULL) 264 *tptrp = (u_int8_t *)(ip6e + 1); 265 else { 266 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 267 return(-1); 268 269 *tptrp = *tptrp + optlen; 270 } 271 if (*tptrp >= lim) { /* there is no option */ 272 *tptrp = NULL; 273 return(-1); 274 } 275 /* 276 * Finally, checks if the next option is safely stored in the 277 * cmsg data. 278 */ 279 if (ip6optlen(*tptrp, lim) == 0) 280 return(-1); 281 else 282 return(0); 283 } 284 285 /* 286 * This function is similar to the inet6_option_next() function, 287 * except this function lets the caller specify the option type to be 288 * searched for, instead of always returning the next option in the 289 * ancillary data object. 290 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 291 * it's a typo. The variable should be type of u_int8_t **. 292 */ 293 int 294 inet6_option_find(cmsg, tptrp, type) 295 const struct cmsghdr *cmsg; 296 u_int8_t **tptrp; 297 int type; 298 { 299 struct ip6_ext *ip6e; 300 int hdrlen, optlen; 301 u_int8_t *optp, *lim; 302 303 if (cmsg->cmsg_level != IPPROTO_IPV6 || 304 (cmsg->cmsg_type != IPV6_HOPOPTS && 305 cmsg->cmsg_type != IPV6_DSTOPTS)) 306 return(-1); 307 308 /* message length validation */ 309 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 310 return(-1); 311 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 312 hdrlen = (ip6e->ip6e_len + 1) << 3; 313 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 314 return(-1); 315 316 /* 317 * If the caller does not specify the starting point, 318 * search from the beginning of the option list. 319 * Otherwise, search from *the next option* of the specified point. 320 */ 321 lim = (u_int8_t *)ip6e + hdrlen; 322 if (*tptrp == NULL) 323 *tptrp = (u_int8_t *)(ip6e + 1); 324 else { 325 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 326 return(-1); 327 328 *tptrp = *tptrp + optlen; 329 } 330 for (optp = *tptrp; optp < lim; optp += optlen) { 331 if (*optp == type) { 332 *tptrp = optp; 333 return(0); 334 } 335 if ((optlen = ip6optlen(optp, lim)) == 0) 336 return(-1); 337 } 338 339 /* search failed */ 340 *tptrp = NULL; 341 return(-1); 342 } 343 344 /* 345 * Calculate the length of a given IPv6 option. Also checks 346 * if the option is safely stored in user's buffer according to the 347 * calculated length and the limitation of the buffer. 348 */ 349 static int 350 ip6optlen(opt, lim) 351 u_int8_t *opt, *lim; 352 { 353 int optlen; 354 355 if (*opt == IP6OPT_PAD1) 356 optlen = 1; 357 else { 358 /* is there enough space to store type and len? */ 359 if (opt + 2 > lim) 360 return(0); 361 optlen = *(opt + 1) + 2; 362 } 363 if (opt + optlen <= lim) 364 return(optlen); 365 366 return(0); 367 } 368 369 static void 370 inet6_insert_padopt(u_char *p, int len) 371 { 372 switch(len) { 373 case 0: 374 return; 375 case 1: 376 p[0] = IP6OPT_PAD1; 377 return; 378 default: 379 p[0] = IP6OPT_PADN; 380 p[1] = len - 2; 381 memset(&p[2], 0, len - 2); 382 return; 383 } 384 } 385
Indexes created Wed Oct 01 19:09:53 GMT 2025