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 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $ 30 * $DragonFly: src/lib/libc/net/ip6opt.c,v 1.3 2004/10/25 19:38:01 drhodus Exp $ 31 */ 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 if (typep[0] > 255) 115 return(-1); 116 117 /* 118 * If this is the first option, allocate space for the 119 * first 2 bytes(for next header and length fields) of 120 * the option header. 121 */ 122 if (bp == (u_char *)eh) { 123 bp += 2; 124 cmsg->cmsg_len += 2; 125 } 126 127 /* calculate pad length before the option. */ 128 off = bp - (u_char *)eh; 129 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 130 (off % multx); 131 padlen += plusy; 132 /* insert padding */ 133 inet6_insert_padopt(bp, padlen); 134 cmsg->cmsg_len += padlen; 135 bp += padlen; 136 137 /* copy the option */ 138 if (typep[0] == IP6OPT_PAD1) 139 optlen = 1; 140 else 141 optlen = typep[1] + 2; 142 memcpy(bp, typep, optlen); 143 bp += optlen; 144 cmsg->cmsg_len += optlen; 145 146 /* calculate pad length after the option and insert the padding */ 147 off = bp - (u_char *)eh; 148 padlen = ((off + 7) & ~7) - off; 149 inet6_insert_padopt(bp, padlen); 150 bp += padlen; 151 cmsg->cmsg_len += padlen; 152 153 /* update the length field of the ip6 option header */ 154 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 155 156 return(0); 157 } 158 159 /* 160 * This function appends a Hop-by-Hop option or a Destination option 161 * into an ancillary data object that has been initialized by 162 * inet6_option_init(). This function returns a pointer to the 8-bit 163 * option type field that starts the option on success, or NULL on an 164 * error. 165 * The difference between this function and inet6_option_append() is 166 * that the latter copies the contents of a previously built option into 167 * the ancillary data object while the current function returns a 168 * pointer to the space in the data object where the option's TLV must 169 * then be built by the caller. 170 * 171 */ 172 u_int8_t * 173 inet6_option_alloc(cmsg, datalen, multx, plusy) 174 struct cmsghdr *cmsg; 175 int datalen; 176 int multx; 177 int plusy; 178 { 179 int padlen, off; 180 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 181 u_int8_t *retval; 182 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 183 184 /* argument validation */ 185 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 186 return(NULL); 187 if (plusy < 0 || plusy > 7) 188 return(NULL); 189 190 /* 191 * If this is the first option, allocate space for the 192 * first 2 bytes(for next header and length fields) of 193 * the option header. 194 */ 195 if (bp == (u_char *)eh) { 196 bp += 2; 197 cmsg->cmsg_len += 2; 198 } 199 200 /* calculate pad length before the option. */ 201 off = bp - (u_char *)eh; 202 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 203 (off % multx); 204 padlen += plusy; 205 /* insert padding */ 206 inet6_insert_padopt(bp, padlen); 207 cmsg->cmsg_len += padlen; 208 bp += padlen; 209 210 /* keep space to store specified length of data */ 211 retval = bp; 212 bp += datalen; 213 cmsg->cmsg_len += datalen; 214 215 /* calculate pad length after the option and insert the padding */ 216 off = bp - (u_char *)eh; 217 padlen = ((off + 7) & ~7) - off; 218 inet6_insert_padopt(bp, padlen); 219 bp += padlen; 220 cmsg->cmsg_len += padlen; 221 222 /* update the length field of the ip6 option header */ 223 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 224 225 return(retval); 226 } 227 228 /* 229 * This function processes the next Hop-by-Hop option or Destination 230 * option in an ancillary data object. If another option remains to be 231 * processed, the return value of the function is 0 and *tptrp points to 232 * the 8-bit option type field (which is followed by the 8-bit option 233 * data length, followed by the option data). If no more options remain 234 * to be processed, the return value is -1 and *tptrp is NULL. If an 235 * error occurs, the return value is -1 and *tptrp is not NULL. 236 * (RFC 2292, 6.3.5) 237 */ 238 int 239 inet6_option_next(cmsg, tptrp) 240 const struct cmsghdr *cmsg; 241 u_int8_t **tptrp; 242 { 243 struct ip6_ext *ip6e; 244 int hdrlen, optlen; 245 u_int8_t *lim; 246 247 if (cmsg->cmsg_level != IPPROTO_IPV6 || 248 (cmsg->cmsg_type != IPV6_HOPOPTS && 249 cmsg->cmsg_type != IPV6_DSTOPTS)) 250 return(-1); 251 252 /* message length validation */ 253 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 254 return(-1); 255 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 256 hdrlen = (ip6e->ip6e_len + 1) << 3; 257 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 258 return(-1); 259 260 /* 261 * If the caller does not specify the starting point, 262 * simply return the 1st option. 263 * Otherwise, search the option list for the next option. 264 */ 265 lim = (u_int8_t *)ip6e + hdrlen; 266 if (*tptrp == NULL) 267 *tptrp = (u_int8_t *)(ip6e + 1); 268 else { 269 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 270 return(-1); 271 272 *tptrp = *tptrp + optlen; 273 } 274 if (*tptrp >= lim) { /* there is no option */ 275 *tptrp = NULL; 276 return(-1); 277 } 278 /* 279 * Finally, checks if the next option is safely stored in the 280 * cmsg data. 281 */ 282 if (ip6optlen(*tptrp, lim) == 0) 283 return(-1); 284 else 285 return(0); 286 } 287 288 /* 289 * This function is similar to the inet6_option_next() function, 290 * except this function lets the caller specify the option type to be 291 * searched for, instead of always returning the next option in the 292 * ancillary data object. 293 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 294 * it's a typo. The variable should be type of u_int8_t **. 295 */ 296 int 297 inet6_option_find(cmsg, tptrp, type) 298 const struct cmsghdr *cmsg; 299 u_int8_t **tptrp; 300 int type; 301 { 302 struct ip6_ext *ip6e; 303 int hdrlen, optlen; 304 u_int8_t *optp, *lim; 305 306 if (cmsg->cmsg_level != IPPROTO_IPV6 || 307 (cmsg->cmsg_type != IPV6_HOPOPTS && 308 cmsg->cmsg_type != IPV6_DSTOPTS)) 309 return(-1); 310 311 /* message length validation */ 312 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 313 return(-1); 314 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 315 hdrlen = (ip6e->ip6e_len + 1) << 3; 316 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 317 return(-1); 318 319 /* 320 * If the caller does not specify the starting point, 321 * search from the beginning of the option list. 322 * Otherwise, search from *the next option* of the specified point. 323 */ 324 lim = (u_int8_t *)ip6e + hdrlen; 325 if (*tptrp == NULL) 326 *tptrp = (u_int8_t *)(ip6e + 1); 327 else { 328 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 329 return(-1); 330 331 *tptrp = *tptrp + optlen; 332 } 333 for (optp = *tptrp; optp < lim; optp += optlen) { 334 if (*optp == type) { 335 *tptrp = optp; 336 return(0); 337 } 338 if ((optlen = ip6optlen(optp, lim)) == 0) 339 return(-1); 340 } 341 342 /* search failed */ 343 *tptrp = NULL; 344 return(-1); 345 } 346 347 /* 348 * Calculate the length of a given IPv6 option. Also checks 349 * if the option is safely stored in user's buffer according to the 350 * calculated length and the limitation of the buffer. 351 */ 352 static int 353 ip6optlen(opt, lim) 354 u_int8_t *opt, *lim; 355 { 356 int optlen; 357 358 if (*opt == IP6OPT_PAD1) 359 optlen = 1; 360 else { 361 /* is there enough space to store type and len? */ 362 if (opt + 2 > lim) 363 return(0); 364 optlen = *(opt + 1) + 2; 365 } 366 if (opt + optlen <= lim) 367 return(optlen); 368 369 return(0); 370 } 371 372 static void 373 inet6_insert_padopt(u_char *p, int len) 374 { 375 switch(len) { 376 case 0: 377 return; 378 case 1: 379 p[0] = IP6OPT_PAD1; 380 return; 381 default: 382 p[0] = IP6OPT_PADN; 383 p[1] = len - 2; 384 memset(&p[2], 0, len - 2); 385 return; 386 } 387 } 388