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 1.5 2006/07/08 01:04:28 swildner 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(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(void *bp, struct cmsghdr **cmsgp, int type) 69 { 70 struct cmsghdr *ch = (struct cmsghdr *)bp; 71 72 /* argument validation */ 73 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) 74 return(-1); 75 76 ch->cmsg_level = IPPROTO_IPV6; 77 ch->cmsg_type = type; 78 ch->cmsg_len = CMSG_LEN(0); 79 80 *cmsgp = ch; 81 return(0); 82 } 83 84 /* 85 * This function appends a Hop-by-Hop option or a Destination option 86 * into an ancillary data object that has been initialized by 87 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 88 * an error. 89 * multx is the value x in the alignment term "xn + y" described 90 * earlier. It must have a value of 1, 2, 4, or 8. 91 * plusy is the value y in the alignment term "xn + y" described 92 * earlier. It must have a value between 0 and 7, inclusive. 93 */ 94 int 95 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx, 96 int plusy) 97 { 98 int padlen, optlen, off; 99 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 100 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 101 102 /* argument validation */ 103 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 104 return(-1); 105 if (plusy < 0 || plusy > 7) 106 return(-1); 107 108 /* 109 * If this is the first option, allocate space for the 110 * first 2 bytes(for next header and length fields) of 111 * the option header. 112 */ 113 if (bp == (u_char *)eh) { 114 bp += 2; 115 cmsg->cmsg_len += 2; 116 } 117 118 /* calculate pad length before the option. */ 119 off = bp - (u_char *)eh; 120 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 121 (off % multx); 122 padlen += plusy; 123 /* insert padding */ 124 inet6_insert_padopt(bp, padlen); 125 cmsg->cmsg_len += padlen; 126 bp += padlen; 127 128 /* copy the option */ 129 if (typep[0] == IP6OPT_PAD1) 130 optlen = 1; 131 else 132 optlen = typep[1] + 2; 133 memcpy(bp, typep, optlen); 134 bp += optlen; 135 cmsg->cmsg_len += optlen; 136 137 /* calculate pad length after the option and insert the padding */ 138 off = bp - (u_char *)eh; 139 padlen = ((off + 7) & ~7) - off; 140 inet6_insert_padopt(bp, padlen); 141 bp += padlen; 142 cmsg->cmsg_len += padlen; 143 144 /* update the length field of the ip6 option header */ 145 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 146 147 return(0); 148 } 149 150 /* 151 * This function appends a Hop-by-Hop option or a Destination option 152 * into an ancillary data object that has been initialized by 153 * inet6_option_init(). This function returns a pointer to the 8-bit 154 * option type field that starts the option on success, or NULL on an 155 * error. 156 * The difference between this function and inet6_option_append() is 157 * that the latter copies the contents of a previously built option into 158 * the ancillary data object while the current function returns a 159 * pointer to the space in the data object where the option's TLV must 160 * then be built by the caller. 161 * 162 */ 163 u_int8_t * 164 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy) 165 { 166 int padlen, off; 167 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 168 u_int8_t *retval; 169 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 170 171 /* argument validation */ 172 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 173 return(NULL); 174 if (plusy < 0 || plusy > 7) 175 return(NULL); 176 177 /* 178 * If this is the first option, allocate space for the 179 * first 2 bytes(for next header and length fields) of 180 * the option header. 181 */ 182 if (bp == (u_char *)eh) { 183 bp += 2; 184 cmsg->cmsg_len += 2; 185 } 186 187 /* calculate pad length before the option. */ 188 off = bp - (u_char *)eh; 189 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 190 (off % multx); 191 padlen += plusy; 192 /* insert padding */ 193 inet6_insert_padopt(bp, padlen); 194 cmsg->cmsg_len += padlen; 195 bp += padlen; 196 197 /* keep space to store specified length of data */ 198 retval = bp; 199 bp += datalen; 200 cmsg->cmsg_len += datalen; 201 202 /* calculate pad length after the option and insert the padding */ 203 off = bp - (u_char *)eh; 204 padlen = ((off + 7) & ~7) - off; 205 inet6_insert_padopt(bp, padlen); 206 bp += padlen; 207 cmsg->cmsg_len += padlen; 208 209 /* update the length field of the ip6 option header */ 210 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 211 212 return(retval); 213 } 214 215 /* 216 * This function processes the next Hop-by-Hop option or Destination 217 * option in an ancillary data object. If another option remains to be 218 * processed, the return value of the function is 0 and *tptrp points to 219 * the 8-bit option type field (which is followed by the 8-bit option 220 * data length, followed by the option data). If no more options remain 221 * to be processed, the return value is -1 and *tptrp is NULL. If an 222 * error occurs, the return value is -1 and *tptrp is not NULL. 223 * (RFC 2292, 6.3.5) 224 */ 225 int 226 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp) 227 { 228 struct ip6_ext *ip6e; 229 int hdrlen, optlen; 230 u_int8_t *lim; 231 232 if (cmsg->cmsg_level != IPPROTO_IPV6 || 233 (cmsg->cmsg_type != IPV6_HOPOPTS && 234 cmsg->cmsg_type != IPV6_DSTOPTS)) 235 return(-1); 236 237 /* message length validation */ 238 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 239 return(-1); 240 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 241 hdrlen = (ip6e->ip6e_len + 1) << 3; 242 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 243 return(-1); 244 245 /* 246 * If the caller does not specify the starting point, 247 * simply return the 1st option. 248 * Otherwise, search the option list for the next option. 249 */ 250 lim = (u_int8_t *)ip6e + hdrlen; 251 if (*tptrp == NULL) 252 *tptrp = (u_int8_t *)(ip6e + 1); 253 else { 254 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 255 return(-1); 256 257 *tptrp = *tptrp + optlen; 258 } 259 if (*tptrp >= lim) { /* there is no option */ 260 *tptrp = NULL; 261 return(-1); 262 } 263 /* 264 * Finally, checks if the next option is safely stored in the 265 * cmsg data. 266 */ 267 if (ip6optlen(*tptrp, lim) == 0) 268 return(-1); 269 else 270 return(0); 271 } 272 273 /* 274 * This function is similar to the inet6_option_next() function, 275 * except this function lets the caller specify the option type to be 276 * searched for, instead of always returning the next option in the 277 * ancillary data object. 278 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 279 * it's a typo. The variable should be type of u_int8_t **. 280 */ 281 int 282 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type) 283 { 284 struct ip6_ext *ip6e; 285 int hdrlen, optlen; 286 u_int8_t *optp, *lim; 287 288 if (cmsg->cmsg_level != IPPROTO_IPV6 || 289 (cmsg->cmsg_type != IPV6_HOPOPTS && 290 cmsg->cmsg_type != IPV6_DSTOPTS)) 291 return(-1); 292 293 /* message length validation */ 294 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 295 return(-1); 296 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 297 hdrlen = (ip6e->ip6e_len + 1) << 3; 298 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 299 return(-1); 300 301 /* 302 * If the caller does not specify the starting point, 303 * search from the beginning of the option list. 304 * Otherwise, search from *the next option* of the specified point. 305 */ 306 lim = (u_int8_t *)ip6e + hdrlen; 307 if (*tptrp == NULL) 308 *tptrp = (u_int8_t *)(ip6e + 1); 309 else { 310 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 311 return(-1); 312 313 *tptrp = *tptrp + optlen; 314 } 315 for (optp = *tptrp; optp < lim; optp += optlen) { 316 if (*optp == type) { 317 *tptrp = optp; 318 return(0); 319 } 320 if ((optlen = ip6optlen(optp, lim)) == 0) 321 return(-1); 322 } 323 324 /* search failed */ 325 *tptrp = NULL; 326 return(-1); 327 } 328 329 /* 330 * Calculate the length of a given IPv6 option. Also checks 331 * if the option is safely stored in user's buffer according to the 332 * calculated length and the limitation of the buffer. 333 */ 334 static int 335 ip6optlen(u_int8_t *opt, u_int8_t *lim) 336 { 337 int optlen; 338 339 if (*opt == IP6OPT_PAD1) 340 optlen = 1; 341 else { 342 /* is there enough space to store type and len? */ 343 if (opt + 2 > lim) 344 return(0); 345 optlen = *(opt + 1) + 2; 346 } 347 if (opt + optlen <= lim) 348 return(optlen); 349 350 return(0); 351 } 352 353 static void 354 inet6_insert_padopt(u_char *p, int len) 355 { 356 switch(len) { 357 case 0: 358 return; 359 case 1: 360 p[0] = IP6OPT_PAD1; 361 return; 362 default: 363 p[0] = IP6OPT_PADN; 364 p[1] = len - 2; 365 memset(&p[2], 0, len - 2); 366 return; 367 } 368 } 369