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/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 37 #include <netinet/in.h> 38 #include <netinet/ip6.h> 39 40 #include <string.h> 41 #include <stdio.h> 42 43 static int ip6optlen(u_int8_t *opt, u_int8_t *lim); 44 static void inet6_insert_padopt(u_char *p, int len); 45 46 /* 47 * This function returns the number of bytes required to hold an option 48 * when it is stored as ancillary data, including the cmsghdr structure 49 * at the beginning, and any padding at the end (to make its size a 50 * multiple of 8 bytes). The argument is the size of the structure 51 * defining the option, which must include any pad bytes at the 52 * beginning (the value y in the alignment term "xn + y"), the type 53 * byte, the length byte, and the option data. 54 */ 55 int 56 inet6_option_space(nbytes) 57 int nbytes; 58 { 59 nbytes += 2; /* we need space for nxt-hdr and length fields */ 60 return(CMSG_SPACE((nbytes + 7) & ~7)); 61 } 62 63 /* 64 * This function is called once per ancillary data object that will 65 * contain either Hop-by-Hop or Destination options. It returns 0 on 66 * success or -1 on an error. 67 */ 68 int 69 inet6_option_init(bp, cmsgp, type) 70 void *bp; 71 struct cmsghdr **cmsgp; 72 int type; 73 { 74 struct cmsghdr *ch = (struct cmsghdr *)bp; 75 76 /* argument validation */ 77 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) 78 return(-1); 79 80 ch->cmsg_level = IPPROTO_IPV6; 81 ch->cmsg_type = type; 82 ch->cmsg_len = CMSG_LEN(0); 83 84 *cmsgp = ch; 85 return(0); 86 } 87 88 /* 89 * This function appends a Hop-by-Hop option or a Destination option 90 * into an ancillary data object that has been initialized by 91 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 92 * an error. 93 * multx is the value x in the alignment term "xn + y" described 94 * earlier. It must have a value of 1, 2, 4, or 8. 95 * plusy is the value y in the alignment term "xn + y" described 96 * earlier. It must have a value between 0 and 7, inclusive. 97 */ 98 int 99 inet6_option_append(cmsg, typep, multx, plusy) 100 struct cmsghdr *cmsg; 101 const u_int8_t *typep; 102 int multx; 103 int plusy; 104 { 105 int padlen, optlen, off; 106 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 107 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 108 109 /* argument validation */ 110 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 111 return(-1); 112 if (plusy < 0 || plusy > 7) 113 return(-1); 114 115 /* 116 * If this is the first option, allocate space for the 117 * first 2 bytes(for next header and length fields) of 118 * the option header. 119 */ 120 if (bp == (u_char *)eh) { 121 bp += 2; 122 cmsg->cmsg_len += 2; 123 } 124 125 /* calculate pad length before the option. */ 126 off = bp - (u_char *)eh; 127 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 128 (off % multx); 129 padlen += plusy; 130 /* insert padding */ 131 inet6_insert_padopt(bp, padlen); 132 cmsg->cmsg_len += padlen; 133 bp += padlen; 134 135 /* copy the option */ 136 if (typep[0] == IP6OPT_PAD1) 137 optlen = 1; 138 else 139 optlen = typep[1] + 2; 140 memcpy(bp, typep, optlen); 141 bp += optlen; 142 cmsg->cmsg_len += optlen; 143 144 /* calculate pad length after the option and insert the padding */ 145 off = bp - (u_char *)eh; 146 padlen = ((off + 7) & ~7) - off; 147 inet6_insert_padopt(bp, padlen); 148 bp += padlen; 149 cmsg->cmsg_len += padlen; 150 151 /* update the length field of the ip6 option header */ 152 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 153 154 return(0); 155 } 156 157 /* 158 * This function appends a Hop-by-Hop option or a Destination option 159 * into an ancillary data object that has been initialized by 160 * inet6_option_init(). This function returns a pointer to the 8-bit 161 * option type field that starts the option on success, or NULL on an 162 * error. 163 * The difference between this function and inet6_option_append() is 164 * that the latter copies the contents of a previously built option into 165 * the ancillary data object while the current function returns a 166 * pointer to the space in the data object where the option's TLV must 167 * then be built by the caller. 168 * 169 */ 170 u_int8_t * 171 inet6_option_alloc(cmsg, datalen, multx, plusy) 172 struct cmsghdr *cmsg; 173 int datalen; 174 int multx; 175 int plusy; 176 { 177 int padlen, off; 178 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 179 u_int8_t *retval; 180 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 181 182 /* argument validation */ 183 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 184 return(NULL); 185 if (plusy < 0 || plusy > 7) 186 return(NULL); 187 188 /* 189 * If this is the first option, allocate space for the 190 * first 2 bytes(for next header and length fields) of 191 * the option header. 192 */ 193 if (bp == (u_char *)eh) { 194 bp += 2; 195 cmsg->cmsg_len += 2; 196 } 197 198 /* calculate pad length before the option. */ 199 off = bp - (u_char *)eh; 200 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 201 (off % multx); 202 padlen += plusy; 203 /* insert padding */ 204 inet6_insert_padopt(bp, padlen); 205 cmsg->cmsg_len += padlen; 206 bp += padlen; 207 208 /* keep space to store specified length of data */ 209 retval = bp; 210 bp += datalen; 211 cmsg->cmsg_len += datalen; 212 213 /* calculate pad length after the option and insert the padding */ 214 off = bp - (u_char *)eh; 215 padlen = ((off + 7) & ~7) - off; 216 inet6_insert_padopt(bp, padlen); 217 bp += padlen; 218 cmsg->cmsg_len += padlen; 219 220 /* update the length field of the ip6 option header */ 221 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 222 223 return(retval); 224 } 225 226 /* 227 * This function processes the next Hop-by-Hop option or Destination 228 * option in an ancillary data object. If another option remains to be 229 * processed, the return value of the function is 0 and *tptrp points to 230 * the 8-bit option type field (which is followed by the 8-bit option 231 * data length, followed by the option data). If no more options remain 232 * to be processed, the return value is -1 and *tptrp is NULL. If an 233 * error occurs, the return value is -1 and *tptrp is not NULL. 234 * (RFC 2292, 6.3.5) 235 */ 236 int 237 inet6_option_next(cmsg, tptrp) 238 const struct cmsghdr *cmsg; 239 u_int8_t **tptrp; 240 { 241 struct ip6_ext *ip6e; 242 int hdrlen, optlen; 243 u_int8_t *lim; 244 245 if (cmsg->cmsg_level != IPPROTO_IPV6 || 246 (cmsg->cmsg_type != IPV6_HOPOPTS && 247 cmsg->cmsg_type != IPV6_DSTOPTS)) 248 return(-1); 249 250 /* message length validation */ 251 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 252 return(-1); 253 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 254 hdrlen = (ip6e->ip6e_len + 1) << 3; 255 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 256 return(-1); 257 258 /* 259 * If the caller does not specify the starting point, 260 * simply return the 1st option. 261 * Otherwise, search the option list for the next option. 262 */ 263 lim = (u_int8_t *)ip6e + hdrlen; 264 if (*tptrp == NULL) 265 *tptrp = (u_int8_t *)(ip6e + 1); 266 else { 267 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 268 return(-1); 269 270 *tptrp = *tptrp + optlen; 271 } 272 if (*tptrp >= lim) { /* there is no option */ 273 *tptrp = NULL; 274 return(-1); 275 } 276 /* 277 * Finally, checks if the next option is safely stored in the 278 * cmsg data. 279 */ 280 if (ip6optlen(*tptrp, lim) == 0) 281 return(-1); 282 else 283 return(0); 284 } 285 286 /* 287 * This function is similar to the inet6_option_next() function, 288 * except this function lets the caller specify the option type to be 289 * searched for, instead of always returning the next option in the 290 * ancillary data object. 291 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 292 * it's a typo. The variable should be type of u_int8_t **. 293 */ 294 int 295 inet6_option_find(cmsg, tptrp, type) 296 const struct cmsghdr *cmsg; 297 u_int8_t **tptrp; 298 int type; 299 { 300 struct ip6_ext *ip6e; 301 int hdrlen, optlen; 302 u_int8_t *optp, *lim; 303 304 if (cmsg->cmsg_level != IPPROTO_IPV6 || 305 (cmsg->cmsg_type != IPV6_HOPOPTS && 306 cmsg->cmsg_type != IPV6_DSTOPTS)) 307 return(-1); 308 309 /* message length validation */ 310 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 311 return(-1); 312 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 313 hdrlen = (ip6e->ip6e_len + 1) << 3; 314 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 315 return(-1); 316 317 /* 318 * If the caller does not specify the starting point, 319 * search from the beginning of the option list. 320 * Otherwise, search from *the next option* of the specified point. 321 */ 322 lim = (u_int8_t *)ip6e + hdrlen; 323 if (*tptrp == NULL) 324 *tptrp = (u_int8_t *)(ip6e + 1); 325 else { 326 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 327 return(-1); 328 329 *tptrp = *tptrp + optlen; 330 } 331 for (optp = *tptrp; optp < lim; optp += optlen) { 332 if (*optp == type) { 333 *tptrp = optp; 334 return(0); 335 } 336 if ((optlen = ip6optlen(optp, lim)) == 0) 337 return(-1); 338 } 339 340 /* search failed */ 341 *tptrp = NULL; 342 return(-1); 343 } 344 345 /* 346 * Calculate the length of a given IPv6 option. Also checks 347 * if the option is safely stored in user's buffer according to the 348 * calculated length and the limitation of the buffer. 349 */ 350 static int 351 ip6optlen(opt, lim) 352 u_int8_t *opt, *lim; 353 { 354 int optlen; 355 356 if (*opt == IP6OPT_PAD1) 357 optlen = 1; 358 else { 359 /* is there enough space to store type and len? */ 360 if (opt + 2 > lim) 361 return(0); 362 optlen = *(opt + 1) + 2; 363 } 364 if (opt + optlen <= lim) 365 return(optlen); 366 367 return(0); 368 } 369 370 static void 371 inet6_insert_padopt(u_char *p, int len) 372 { 373 switch(len) { 374 case 0: 375 return; 376 case 1: 377 p[0] = IP6OPT_PAD1; 378 return; 379 default: 380 p[0] = IP6OPT_PADN; 381 p[1] = len - 2; 382 memset(&p[2], 0, len - 2); 383 return; 384 } 385 } 386