diff options
Diffstat (limited to 'inet/inet6_option.c')
| -rw-r--r-- | inet/inet6_option.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/inet/inet6_option.c b/inet/inet6_option.c new file mode 100644 index 0000000000..9a1e8686b9 --- /dev/null +++ b/inet/inet6_option.c @@ -0,0 +1,342 @@ +/* Copyright (C) 2003 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2003. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <assert.h> +#include <string.h> +#include <netinet/in.h> +#include <netinet/ip6.h> +#include <sys/param.h> + + +static void +internal_function +add_pad (struct cmsghdr *cmsg, int len) +{ + unsigned char *p = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0); + + if (len == 1) + /* Special handling for 1, a one-byte solution. */ + *p++ = IP6OPT_PAD1; + else if (len != 0) + { + /* Multibyte padding. */ + *p++ = IP6OPT_PADN; + *p++ = len - 2; /* Discount the two header bytes. */ + /* The rest is filled with zero. */ + memset (p, '\0', len - 2); + p += len - 2; + } + + /* Account for the bytes. */ + cmsg->cmsg_len += len; +} + + +static int +get_opt_end (const uint8_t **result, const uint8_t *startp, + const uint8_t *endp) +{ + if (startp >= endp) + /* Out of bounds. */ + return -1; + + if (*startp == IP6OPT_PAD1) + { + /* Just this one byte. */ + *result = startp + 1; + return 0; + } + + /* Now we know there must be at least two bytes. */ + if (startp + 2 > endp + /* Now we can get the length byte. */ + || startp + startp[1] + 2 > endp) + return -1; + + *result = startp + startp[1] + 2; + + return 0; +} + + +/* RFC 2292, 6.3.1 + + 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 (nbytes) + int nbytes; +{ + /* Add room for the extension header. */ + nbytes += sizeof (struct ip6_ext); + + return CMSG_SPACE (roundup (nbytes, 8)); +} + + +/* RFC 2292, 6.3.2 + + 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 (bp, cmsgp, type) + void *bp; + struct cmsghdr **cmsgp; + int type; +{ + /* Only Hop-by-Hop or Destination options allowed. */ + if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) + return -1; + + /* BP is a pointer to the previously allocated space. */ + struct cmsghdr *newp = (struct cmsghdr *) bp; + + /* Initialize the message header. + + Length: No data yet, only the cmsghdr struct. */ + newp->cmsg_len = CMSG_LEN (0); + /* Originating protocol: obviously IPv6. */ + newp->cmsg_level = IPPROTO_IPV6; + /* Message type. */ + newp->cmsg_type = type; + + /* Pass up the result. */ + *cmsgp = newp; + + return 0; +} + + +/* RFC 2292, 6.3.3 + + 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. */ +int +inet6_option_append (cmsg, typep, multx, plusy) + struct cmsghdr *cmsg; + const uint8_t *typep; + int multx; + int plusy; +{ + /* typep is a pointer to the 8-bit option type. It is assumed that this + field is immediately followed by the 8-bit option data length field, + which is then followed immediately by the option data. + + The option types IP6OPT_PAD1 and IP6OPT_PADN also must be handled. */ + int len = typep[0] == IP6OPT_PAD1 ? 1 : typep[1] + 2; + + /* Get the pointer to the space in the message. */ + uint8_t *ptr = inet6_option_alloc (cmsg, len, multx, plusy); + if (ptr == NULL) + /* Some problem with the parameters. */ + return -1; + + /* Copy the content. */ + memcpy (ptr, typep, len); + + return 0; +} + + +/* RFC 2292, 6.3.4 + + 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. */ +uint8_t * +inet6_option_alloc (cmsg, datalen, multx, plusy) + struct cmsghdr *cmsg; + int datalen; + int multx; + int plusy; +{ + /* The RFC limits the value of the alignment values. */ + if ((multx != 1 && multx != 2 && multx != 4 && multx != 8) + || ! (plusy >= 0 && plusy <= 7)) + return NULL; + + /* Current data size. */ + int dsize = cmsg->cmsg_len - CMSG_LEN (0); + + /* The first two bytes of the option are for the extended header. */ + if (__builtin_expect (dsize == 0, 0)) + { + cmsg->cmsg_len += sizeof (struct ip6_ext); + dsize = sizeof (struct ip6_ext); + } + + /* First add padding. */ + add_pad (cmsg, ((multx - (dsize & (multx - 1))) & (multx - 1)) + plusy); + + /* Return the pointer to the start of the option space. */ + uint8_t *result = CMSG_DATA (cmsg) + cmsg->cmsg_len - CMSG_LEN (0); + cmsg->cmsg_len += datalen; + + /* The extended option header length is measured in 8-byte groups. + To represent the current length we might have to add padding. */ + dsize = cmsg->cmsg_len - CMSG_LEN (0); + add_pad (cmsg, (8 - (dsize & (8 - 1))) & (8 - 1)); + + /* Record the new length of the option. */ + assert (((cmsg->cmsg_len - CMSG_LEN (0)) % 8) == 0); + int len8b = (cmsg->cmsg_len - CMSG_LEN (0)) / 8 - 1; + if (len8b >= 256) + /* Too long. */ + return NULL; + + ((struct ip6_ext *) CMSG_DATA (cmsg))->ip6e_len = len8b; + + return result; +} + + +/* RFC 2292, 6.3.5 + + 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. */ +int +inet6_option_next (cmsg, tptrp) + const struct cmsghdr *cmsg; + uint8_t **tptrp; +{ + /* Make sure it is an option of the right type. */ + if (cmsg->cmsg_level != IPPROTO_IPV6 + || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS)) + return -1; + + /* Pointer to the extension header. We only compute the address, we + don't access anything yet. */ + const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg); + + /* Make sure the message is long enough. */ + if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext)) + /* Now we can access the extension header. */ + || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8)) + /* Too small. */ + return -1; + + /* Determine the address of the byte past the message. */ + const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8; + + const uint8_t *result; + if (tptrp == NULL) + /* This is the first call, return the first option if there is one. */ + result = (const uint8_t *) (ip6e + 1); + else + { + /* Make sure *TPTRP points to a beginning of a new option in + the message. The upper limit is checked in get_opt_end. */ + if (*tptrp < (const uint8_t *) (ip6e + 1)) + return -1; + + /* Get the beginning of the next option. */ + if (get_opt_end (&result, *tptrp, endp) != 0) + return -1; + } + + /* We know where the next option starts. */ + *tptrp = (uint8_t *) result; + + /* Check the option is fully represented in the message. */ + return get_opt_end (&result, result, endp); +} + + +/* RFC 2292, 6.3.6 + + This function is similar to the previously described + 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. cmsg is a + pointer to cmsghdr structure of which cmsg_level equals IPPROTO_IPV6 + and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS. */ +int +inet6_option_find (cmsg, tptrp, type) + const struct cmsghdr *cmsg; + uint8_t **tptrp; + int type; +{ + /* Make sure it is an option of the right type. */ + if (cmsg->cmsg_level != IPPROTO_IPV6 + || (cmsg->cmsg_type != IPV6_HOPOPTS && cmsg->cmsg_type != IPV6_DSTOPTS)) + return -1; + + /* Pointer to the extension header. We only compute the address, we + don't access anything yet. */ + const struct ip6_ext *ip6e = (const struct ip6_ext *) CMSG_DATA (cmsg); + + /* Make sure the message is long enough. */ + if (cmsg->cmsg_len < CMSG_LEN (sizeof (struct ip6_ext)) + /* Now we can access the extension header. */ + || cmsg->cmsg_len < CMSG_LEN ((ip6e->ip6e_len + 1) * 8)) + /* Too small. */ + return -1; + + /* Determine the address of the byte past the message. */ + const uint8_t *endp = CMSG_DATA (cmsg) + (ip6e->ip6e_len + 1) * 8; + + const uint8_t *next; + if (tptrp == NULL) + /* This is the first call, return the first option if there is one. */ + next = (const uint8_t *) (ip6e + 1); + else + { + /* Make sure *TPTRP points to a beginning of a new option in + the message. The upper limit is checked in get_opt_end. */ + if (*tptrp < (const uint8_t *) (ip6e + 1)) + return -1; + + /* Get the beginning of the next option. */ + if (get_opt_end (&next, *tptrp, endp) != 0) + return -1; + } + + /* Now search for the appropriate typed entry. */ + const uint8_t *result; + do + { + result = next; + + /* Get the end of this entry. */ + if (get_opt_end (&next, result, endp) != 0) + return -1; + } + while (*result != type); + + /* We know where the next option starts. */ + *tptrp = (uint8_t *) result; + + /* Success. */ + return 0; +} |