/* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <string.h>
#include <stdio.h>
static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
static void inet6_insert_padopt(u_char *p, int len);
#ifndef IPV6_2292HOPOPTS
#define IPV6_2292HOPOPTS 22
#endif
#ifndef IPV6_2292DSTOPTS
#define IPV6_2292DSTOPTS 23
#endif
#define is_ipv6_hopopts(x) \
((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
#define is_ipv6_dstopts(x) \
((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
/*
* This function returns the number of bytes required to hold an option
* when it is stored as ancillary data, including the cmsghdr structure
* at the beginning, and any padding at the end (to make its size a
* multiple of 8 bytes). The argument is the size of the structure
* defining the option, which must include any pad bytes at the
* beginning (the value y in the alignment term "xn + y"), the type
* byte, the length byte, and the option data.
*/
int
inet6_option_space(int nbytes)
{
nbytes += 2; /* we need space for nxt-hdr and length fields */
return(CMSG_SPACE((nbytes + 7) & ~7));
}
/*
* This function is called once per ancillary data object that will
* contain either Hop-by-Hop or Destination options. It returns 0 on
* success or -1 on an error.
*/
int
inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
{
struct cmsghdr *ch = (struct cmsghdr *)bp;
/* argument validation */
if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
return(-1);
ch->cmsg_level = IPPROTO_IPV6;
ch->cmsg_type = type;
ch->cmsg_len = CMSG_LEN(0);
*cmsgp = ch;
return(0);
}
/*
* This function appends a Hop-by-Hop option or a Destination option
* into an ancillary data object that has been initialized by
* inet6_option_init(). This function returns 0 if it succeeds or -1 on
* an error.
* multx is the value x in the alignment term "xn + y" described
* earlier. It must have a value of 1, 2, 4, or 8.
* plusy is the value y in the alignment term "xn + y" described
* earlier. It must have a value between 0 and 7, inclusive.
*/
int
inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
int plusy)
{
int padlen, optlen, off;
u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
/* argument validation */
if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
return(-1);
if (plusy < 0 || plusy > 7)
return(-1);
/*
* If this is the first option, allocate space for the
* first 2 bytes(for next header and length fields) of
* the option header.
*/
if (bp == (u_char *)eh) {
bp += 2;
cmsg->cmsg_len += 2;
}
/* calculate pad length before the option. */
off = bp - (u_char *)eh;
padlen = roundup2(off % multx, multx) - (off % multx);
padlen += plusy;
padlen %= multx; /* keep the pad as short as possible */
/* insert padding */
inet6_insert_padopt(bp, padlen);
cmsg->cmsg_len += padlen;
bp += padlen;
/* copy the option */
if (typep[0] == IP6OPT_PAD1)
optlen = 1;
else
optlen = typep[1] + 2;
memcpy(bp, typep, optlen);
bp += optlen;
cmsg->cmsg_len += optlen;
/* calculate pad length after the option and insert the padding */
off = bp - (u_char *)eh;
padlen = ((off + 7) & ~7) - off;
inet6_insert_padopt(bp, padlen);
bp += padlen;
cmsg->cmsg_len += padlen;
/* update the length field of the ip6 option header */
eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
return(0);
}
/*
* This function appends a Hop-by-Hop option or a Destination option
* into an ancillary data object that has been initialized by
* inet6_option_init(). This function returns a pointer to the 8-bit
* option type field that starts the option on success, or NULL on an
* error.
* The difference between this function and inet6_option_append() is
* that the latter copies the contents of a previously built option into
* the ancillary data object while the current function returns a
* pointer to the space in the data object where the option's TLV must
* then be built by the caller.
*
*/
u_int8_t *
inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
{
int padlen, off;
u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
u_int8_t *retval;
struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
/* argument validation */
if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
return(NULL);
if (plusy < 0 || plusy > 7)
return(NULL);
/*
* If this is the first option, allocate space for the
* first 2 bytes(for next header and length fields) of
* the option header.
*/
if (bp == (u_char *)eh) {
bp += 2;
cmsg->cmsg_len += 2;
}
/* calculate pad length before the option. */
off = bp - (u_char *)eh;
padlen = roundup2(off % multx, multx) - (off % multx);
padlen += plusy;
padlen %= multx; /* keep the pad as short as possible */
/* insert padding */
inet6_insert_padopt(bp, padlen);
cmsg->cmsg_len += padlen;
bp += padlen;
/* keep space to store specified length of data */
retval = bp;
bp += datalen;
cmsg->cmsg_len += datalen;
/* calculate pad length after the option and insert the padding */
off = bp - (u_char *)eh;
padlen = ((off + 7) & ~7) - off;
inet6_insert_padopt(bp, padlen);
bp += padlen;
cmsg->cmsg_len += padlen;
/* update the length field of the ip6 option header */
eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
return(retval);
}
/*
* This function processes the next Hop-by-Hop option or Destination
* option in an ancillary data object. If another option remains to be
* processed, the return value of the function is 0 and *tptrp points to
* the 8-bit option type field (which is followed by the 8-bit option
* data length, followed by the option data). If no more options remain
* to be processed, the return value is -1 and *tptrp is NULL. If an
* error occurs, the return value is -1 and *tptrp is not NULL.
* (RFC 2292, 6.3.5)
*/
int
inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
{
struct ip6_ext *ip6e;
int hdrlen, optlen;
u_int8_t *lim;
if (cmsg->cmsg_level != IPPROTO_IPV6 ||
(!is_ipv6_hopopts(cmsg->cmsg_type) &&
!is_ipv6_dstopts(cmsg->cmsg_type)))
return(-1);
/* message length validation */
if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
return(-1);
ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
hdrlen = (ip6e->ip6e_len + 1) << 3;
if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
return(-1);
/*
* If the caller does not specify the starting point,
* simply return the 1st option.
* Otherwise, search the option list for the next option.
*/
lim = (u_int8_t *)ip6e + hdrlen;
if (*tptrp == NULL)
*tptrp = (u_int8_t *)(ip6e + 1);
else {
if ((optlen = ip6optlen(*tptrp, lim)) == 0)
return(-1);
*tptrp = *tptrp + optlen;
}
if (*tptrp >= lim) { /* there is no option */
*tptrp = NULL;
return(-1);
}
/*
* Finally, checks if the next option is safely stored in the
* cmsg data.
*/
if (ip6optlen(*tptrp, lim) == 0)
return(-1);
else
return(0);
}
/*
* This function is similar to the inet6_option_next() function,
* except this function lets the caller specify the option type to be
* searched for, instead of always returning the next option in the
* ancillary data object.
* Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
* it's a typo. The variable should be type of u_int8_t **.
*/
int
inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
{
struct ip6_ext *ip6e;
int hdrlen, optlen;
u_int8_t *optp, *lim;
if (cmsg->cmsg_level != IPPROTO_IPV6 ||
(!is_ipv6_hopopts(cmsg->cmsg_type) &&
!is_ipv6_dstopts(cmsg->cmsg_type)))
return(-1);
/* message length validation */
if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
return(-1);
ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
hdrlen = (ip6e->ip6e_len + 1) << 3;
if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
return(-1);
/*
* If the caller does not specify the starting point,
* search from the beginning of the option list.
* Otherwise, search from *the next option* of the specified point.
*/
lim = (u_int8_t *)ip6e + hdrlen;
if (*tptrp == NULL)
*tptrp = (u_int8_t *)(ip6e + 1);
else {
if ((optlen = ip6optlen(*tptrp, lim)) == 0)
return(-1);
*tptrp = *tptrp + optlen;
}
for (optp = *tptrp; optp < lim; optp += optlen) {
if (*optp == type) {
*tptrp = optp;
return(0);
}
if ((optlen = ip6optlen(optp, lim)) == 0)
return(-1);
}
/* search failed */
*tptrp = NULL;
return(-1);
}
/*
* Calculate the length of a given IPv6 option. Also checks
* if the option is safely stored in user's buffer according to the
* calculated length and the limitation of the buffer.
*/
static int
ip6optlen(u_int8_t *opt, u_int8_t *lim)
{
int optlen;
if (*opt == IP6OPT_PAD1)
optlen = 1;
else {
/* is there enough space to store type and len? */
if (opt + 2 > lim)
return(0);
optlen = *(opt + 1) + 2;
}
if (opt + optlen <= lim)
return(optlen);
return(0);
}
static void
inet6_insert_padopt(u_char *p, int len)
{
switch(len) {
case 0:
return;
case 1:
p[0] = IP6OPT_PAD1;
return;
default:
p[0] = IP6OPT_PADN;
p[1] = len - 2;
memset(&p[2], 0, len - 2);
return;
}
}
/*
* The following functions are defined in RFC3542, which is a successor
* of RFC2292.
*/
int
inet6_opt_init(void *extbuf, socklen_t extlen)
{
struct ip6_ext *ext = (struct ip6_ext *)extbuf;
if (ext) {
if (extlen <= 0 || (extlen % 8))
return(-1);
ext->ip6e_len = (extlen >> 3) - 1;
}
return(2); /* sizeof the next and the length fields */
}
int
inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
socklen_t len, u_int8_t align, void **databufp)
{
int currentlen = offset, padlen = 0;
/*
* The option type must have a value from 2 to 255, inclusive.
* (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
*/
if (type < 2)
return(-1);
/*
* The option data length must have a value between 0 and 255,
* inclusive, and is the length of the option data that follows.
*/
if (len > 255 || len < 0 )
return(-1);
/*
* The align parameter must have a value of 1, 2, 4, or 8.
* The align value can not exceed the value of len.
*/
if (align != 1 && align != 2 && align != 4 && align != 8)
return(-1);
if (align > len)
return(-1);
/* Calculate the padding length. */
currentlen += 2 + len; /* 2 means "type + len" */
if (currentlen % align)
padlen = align - (currentlen % align);
/* The option must fit in the extension header buffer. */
currentlen += padlen;
if (extlen && /* XXX: right? */
currentlen > extlen)
return(-1);
if (extbuf) {
u_int8_t *optp = (u_int8_t *)extbuf + offset;
if (padlen == 1) {
/* insert a Pad1 option */
*optp = IP6OPT_PAD1;
optp++;
}
else if (padlen > 0) {
/* insert a PadN option for alignment */
*optp++ = IP6OPT_PADN;
*optp++ = padlen - 2;
memset(optp, 0, padlen - 2);
optp += (padlen - 2);
}
*optp++ = type;
*optp++ = len;
*databufp = optp;
}
return(currentlen);
}
int
inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
{
int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
if (extbuf) {
u_int8_t *padp;
int padlen = updatelen - offset;
if (updatelen > extlen)
return(-1);
padp = (u_int8_t *)extbuf + offset;
if (padlen == 1)
*padp = IP6OPT_PAD1;
else if (padlen > 0) {
*padp++ = IP6OPT_PADN;
*padp++ = (padlen - 2);
memset(padp, 0, padlen - 2);
}
}
return(updatelen);
}
int
inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
{
memcpy((u_int8_t *)databuf + offset, val, vallen);
return(offset + vallen);
}
int
inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
socklen_t *lenp, void **databufp)
{
u_int8_t *optp, *lim;
int optlen;
/* Validate extlen. XXX: is the variable really necessary?? */
if (extlen == 0 || (extlen % 8))
return(-1);
lim = (u_int8_t *)extbuf + extlen;
/*
* If this is the first time this function called for this options
* header, simply return the 1st option.
* Otherwise, search the option list for the next option.
*/
if (offset == 0) {
optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
}
else
optp = (u_int8_t *)extbuf + offset;
/* Find the next option skipping any padding options. */
while(optp < lim) {
switch(*optp) {
case IP6OPT_PAD1:
optp++;
break;
case IP6OPT_PADN:
if ((optlen = ip6optlen(optp, lim)) == 0)
goto optend;
optp += optlen;
break;
default: /* found */
if ((optlen = ip6optlen(optp, lim)) == 0)
goto optend;
*typep = *optp;
*lenp = optlen - 2;
*databufp = optp + 2;
return(optp + optlen - (u_int8_t *)extbuf);
}
}
optend:
*databufp = NULL; /* for safety */
return(-1);
}
int
inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
socklen_t *lenp, void **databufp)
{
u_int8_t *optp, *lim;
int optlen;
/* Validate extlen. XXX: is the variable really necessary?? */
if (extlen == 0 || (extlen % 8))
return(-1);
lim = (u_int8_t *)extbuf + extlen;
/*
* If this is the first time this function called for this options
* header, simply return the 1st option.
* Otherwise, search the option list for the next option.
*/
if (offset == 0) {
optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
}
else
optp = (u_int8_t *)extbuf + offset;
/* Find the specified option */
while(optp < lim) {
if ((optlen = ip6optlen(optp, lim)) == 0)
goto optend;
if (*optp == type) { /* found */
*lenp = optlen - 2;
*databufp = optp + 2;
return(optp + optlen - (u_int8_t *)extbuf);
}
optp += optlen;
}
optend:
*databufp = NULL; /* for safety */
return(-1);
}
int
inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
{
/* we can't assume alignment here */
memcpy(val, (u_int8_t *)databuf + offset, vallen);
return(offset + vallen);
}