ip6opt.c revision 1.2
1 /* $NetBSD: ip6opt.c,v 1.2 1999/07/04 00:43:44 itojun Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 36 #include <netinet/in.h> 37 #include <netinet/ip6.h> 38 39 #include <string.h> 40 #include <stdio.h> 41 42 static int ip6optlen(u_int8_t *opt, u_int8_t *lim); 43 static void inet6_insert_padopt(u_char *p, int len); 44 45 /* 46 * This function returns the number of bytes required to hold an option 47 * when it is stored as ancillary data, including the cmsghdr structure 48 * at the beginning, and any padding at the end (to make its size a 49 * multiple of 8 bytes). The argument is the size of the structure 50 * defining the option, which must include any pad bytes at the 51 * beginning (the value y in the alignment term "xn + y"), the type 52 * byte, the length byte, and the option data. 53 */ 54 int 55 inet6_option_space(nbytes) 56 int nbytes; 57 { 58 nbytes += 2; /* we need space for nxt-hdr and length fields */ 59 return(CMSG_SPACE((nbytes + 7) & ~7)); 60 } 61 62 /* 63 * This function is called once per ancillary data object that will 64 * contain either Hop-by-Hop or Destination options. It returns 0 on 65 * success or -1 on an error. 66 */ 67 int 68 inet6_option_init(bp, cmsgp, type) 69 void *bp; 70 struct cmsghdr **cmsgp; 71 int type; 72 { 73 register struct cmsghdr *ch = (struct cmsghdr *)bp; 74 75 /* argument validation */ 76 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) 77 return(-1); 78 79 ch->cmsg_level = IPPROTO_IPV6; 80 ch->cmsg_type = type; 81 ch->cmsg_len = CMSG_LEN(0); 82 83 *cmsgp = ch; 84 return(0); 85 } 86 87 /* 88 * This function appends a Hop-by-Hop option or a Destination option 89 * into an ancillary data object that has been initialized by 90 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 91 * an error. 92 * multx is the value x in the alignment term "xn + y" described 93 * earlier. It must have a value of 1, 2, 4, or 8. 94 * plusy is the value y in the alignment term "xn + y" described 95 * earlier. It must have a value between 0 and 7, inclusive. 96 */ 97 int 98 inet6_option_append(cmsg, typep, multx, plusy) 99 struct cmsghdr *cmsg; 100 const u_int8_t *typep; 101 int multx; 102 int plusy; 103 { 104 int padlen, optlen, off; 105 register u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 106 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 107 108 /* argument validation */ 109 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 110 return(-1); 111 if (plusy < 0 || plusy > 7) 112 return(-1); 113 if (typep[0] > 255) 114 return(-1); 115 116 /* 117 * If this is the first option, allocate space for the 118 * first 2 bytes(for next header and length fields) of 119 * the option header. 120 */ 121 if (bp == (u_char *)eh) { 122 bp += 2; 123 cmsg->cmsg_len += 2; 124 } 125 126 /* calculate pad length before the option. */ 127 off = bp - (u_char *)eh; 128 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 129 (off % multx); 130 padlen += plusy; 131 /* insert padding */ 132 inet6_insert_padopt(bp, padlen); 133 cmsg->cmsg_len += padlen; 134 bp += padlen; 135 136 /* copy the option */ 137 if (typep[0] == IP6OPT_PAD1) 138 optlen = 1; 139 else 140 optlen = typep[1] + 2; 141 memcpy(bp, typep, optlen); 142 bp += optlen; 143 cmsg->cmsg_len += optlen; 144 145 /* calculate pad length after the option and insert the padding */ 146 off = bp - (u_char *)eh; 147 padlen = ((off + 7) & ~7) - off; 148 inet6_insert_padopt(bp, padlen); 149 bp += padlen; 150 cmsg->cmsg_len += padlen; 151 152 /* update the length field of the ip6 option header */ 153 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 154 155 return(0); 156 } 157 158 /* 159 * This function appends a Hop-by-Hop option or a Destination option 160 * into an ancillary data object that has been initialized by 161 * inet6_option_init(). This function returns a pointer to the 8-bit 162 * option type field that starts the option on success, or NULL on an 163 * error. 164 * The difference between this function and inet6_option_append() is 165 * that the latter copies the contents of a previously built option into 166 * the ancillary data object while the current function returns a 167 * pointer to the space in the data object where the option's TLV must 168 * then be built by the caller. 169 * 170 */ 171 u_int8_t * 172 inet6_option_alloc(cmsg, datalen, multx, plusy) 173 struct cmsghdr *cmsg; 174 int datalen; 175 int multx; 176 int plusy; 177 { 178 int padlen, off; 179 register u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 180 u_int8_t *retval; 181 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 182 183 /* argument validation */ 184 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 185 return(NULL); 186 if (plusy < 0 || plusy > 7) 187 return(NULL); 188 189 /* 190 * If this is the first option, allocate space for the 191 * first 2 bytes(for next header and length fields) of 192 * the option header. 193 */ 194 if (bp == (u_char *)eh) { 195 bp += 2; 196 cmsg->cmsg_len += 2; 197 } 198 199 /* calculate pad length before the option. */ 200 off = bp - (u_char *)eh; 201 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 202 (off % multx); 203 padlen += plusy; 204 /* insert padding */ 205 inet6_insert_padopt(bp, padlen); 206 cmsg->cmsg_len += padlen; 207 bp += padlen; 208 209 /* keep space to store specified length of data */ 210 retval = bp; 211 bp += datalen; 212 cmsg->cmsg_len += datalen; 213 214 /* calculate pad length after the option and insert the padding */ 215 off = bp - (u_char *)eh; 216 padlen = ((off + 7) & ~7) - off; 217 inet6_insert_padopt(bp, padlen); 218 bp += padlen; 219 cmsg->cmsg_len += padlen; 220 221 /* update the length field of the ip6 option header */ 222 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 223 224 return(retval); 225 } 226 227 /* 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. 235 * (RFC 2292, 6.3.5) 236 */ 237 int 238 inet6_option_next(cmsg, tptrp) 239 const struct cmsghdr *cmsg; 240 u_int8_t **tptrp; 241 { 242 struct ip6_ext *ip6e; 243 int hdrlen, optlen; 244 u_int8_t *lim; 245 246 if (cmsg->cmsg_level != IPPROTO_IPV6 || 247 (cmsg->cmsg_type != IPV6_HOPOPTS && 248 cmsg->cmsg_type != IPV6_DSTOPTS)) 249 return(-1); 250 251 /* message length validation */ 252 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 253 return(-1); 254 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 255 hdrlen = (ip6e->ip6e_len + 1) << 3; 256 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 257 return(-1); 258 259 /* 260 * If the caller does not specify the starting point, 261 * simply return the 1st option. 262 * Otherwise, search the option list for the next option. 263 */ 264 lim = (u_int8_t *)ip6e + hdrlen; 265 if (*tptrp == NULL) 266 *tptrp = (u_int8_t *)(ip6e + 1); 267 else { 268 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 269 return(-1); 270 271 *tptrp = *tptrp + optlen; 272 } 273 if (*tptrp >= lim) { /* there is no option */ 274 *tptrp = NULL; 275 return(-1); 276 } 277 /* 278 * Finally, checks if the next option is safely stored in the 279 * cmsg data. 280 */ 281 if (ip6optlen(*tptrp, lim) == 0) 282 return(-1); 283 else 284 return(0); 285 } 286 287 /* 288 * This function is similar to the inet6_option_next() function, 289 * except this function lets the caller specify the option type to be 290 * searched for, instead of always returning the next option in the 291 * ancillary data object. 292 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 293 * it's a typo. The variable should be type of u_int8_t **. 294 */ 295 int 296 inet6_option_find(cmsg, tptrp, type) 297 const struct cmsghdr *cmsg; 298 u_int8_t **tptrp; 299 int type; 300 { 301 struct ip6_ext *ip6e; 302 int hdrlen, optlen; 303 u_int8_t *optp, *lim; 304 305 if (cmsg->cmsg_level != IPPROTO_IPV6 || 306 (cmsg->cmsg_type != IPV6_HOPOPTS && 307 cmsg->cmsg_type != IPV6_DSTOPTS)) 308 return(-1); 309 310 /* message length validation */ 311 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 312 return(-1); 313 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 314 hdrlen = (ip6e->ip6e_len + 1) << 3; 315 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 316 return(-1); 317 318 /* 319 * If the caller does not specify the starting point, 320 * search from the beginning of the option list. 321 * Otherwise, search from *the next option* of the specified point. 322 */ 323 lim = (u_int8_t *)ip6e + hdrlen; 324 if (*tptrp == NULL) 325 *tptrp = (u_int8_t *)(ip6e + 1); 326 else { 327 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 328 return(-1); 329 330 *tptrp = *tptrp + optlen; 331 } 332 for (optp = *tptrp; optp < lim; optp += optlen) { 333 if (*optp == type) { 334 *tptrp = optp; 335 return(0); 336 } 337 if ((optlen = ip6optlen(optp, lim)) == 0) 338 return(-1); 339 } 340 341 /* search failed */ 342 *tptrp = NULL; 343 return(-1); 344 } 345 346 /* 347 * Calculate the length of a given IPv6 option. Also checks 348 * if the option is safely stored in user's buffer according to the 349 * calculated length and the limitation of the buffer. 350 */ 351 static int 352 ip6optlen(opt, lim) 353 u_int8_t *opt, *lim; 354 { 355 int optlen; 356 357 if (*opt == IP6OPT_PAD1) 358 optlen = 1; 359 else { 360 /* is there enough space to store type and len? */ 361 if (opt + 2 > lim) 362 return(0); 363 optlen = *(opt + 1) + 2; 364 } 365 if (opt + optlen <= lim) 366 return(optlen); 367 368 return(0); 369 } 370 371 static void 372 inet6_insert_padopt(u_char *p, int len) 373 { 374 switch(len) { 375 case 0: 376 return; 377 case 1: 378 p[0] = IP6OPT_PAD1; 379 return; 380 default: 381 p[0] = IP6OPT_PADN; 382 p[1] = len - 2; 383 memset(&p[2], 0, len - 2); 384 return; 385 } 386 } 387
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