282 lines
8.0 KiB
C
282 lines
8.0 KiB
C
/* Copyright (C) 2006-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2006.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <string.h>
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#include <netinet/in.h>
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#include <netinet/ip6.h>
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/* RFC 3542, 10.1
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This function returns the number of bytes needed for the empty
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extension header i.e., without any options. If EXTBUF is not NULL it
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also initializes the extension header to have the correct length
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field. In that case if the EXTLEN value is not a positive (i.e.,
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non-zero) multiple of 8 the function fails and returns -1. */
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int
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inet6_opt_init (void *extbuf, socklen_t extlen)
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{
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if (extbuf != NULL)
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{
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if (extlen <= 0 || (extlen % 8) != 0 || extlen > 256 * 8)
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return -1;
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/* Fill in the length in units of 8 octets. */
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struct ip6_hbh *extp = (struct ip6_hbh *) extbuf;
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/* RFC 2460 requires that the header extension length is the
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length of the option header in 8-byte units, not including
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the first 8 bytes. Hence we have to subtract one. */
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extp->ip6h_len = extlen / 8 - 1;
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}
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return sizeof (struct ip6_hbh);
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}
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static void
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add_padding (uint8_t *extbuf, int offset, int npad)
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{
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if (npad == 1)
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extbuf[offset] = IP6OPT_PAD1;
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else if (npad > 0)
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{
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struct ip6_opt *pad_opt = (struct ip6_opt *) (extbuf + offset);
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pad_opt->ip6o_type = IP6OPT_PADN;
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pad_opt->ip6o_len = npad - sizeof (struct ip6_opt);
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/* Clear the memory used by the padding. */
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memset (pad_opt + 1, '\0', pad_opt->ip6o_len);
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}
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}
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/* RFC 3542, 10.2
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This function returns the updated total length taking into account
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adding an option with length 'len' and alignment 'align'. If
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EXTBUF is not NULL then, in addition to returning the length, the
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function inserts any needed pad option, initializes the option
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(setting the type and length fields) and returns a pointer to the
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location for the option content in databufp. If the option does
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not fit in the extension header buffer the function returns -1. */
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int
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inet6_opt_append (void *extbuf, socklen_t extlen, int offset, uint8_t type,
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socklen_t len, uint8_t align, void **databufp)
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{
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/* Check minimum offset. */
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if (offset < sizeof (struct ip6_hbh))
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return -1;
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/* One cannot add padding options. */
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if (type == IP6OPT_PAD1 || type == IP6OPT_PADN)
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return -1;
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/* The option length must fit in one octet. */
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if (len > 255)
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return -1;
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/* The alignment can only by 1, 2, 4, or 8 and must not exceed the
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option length. */
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if (align == 0 || align > 8 || (align & (align - 1)) != 0 || align > len)
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return -1;
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/* Determine the needed padding for alignment. Following the
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current content of the buffer we have the is the IPv6 option type
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and length, followed immediately by the data. The data has the
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alignment constraints. Therefore padding must be inserted in the
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form of padding options before the new option. */
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int data_offset = offset + sizeof (struct ip6_opt);
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int npad = (align - data_offset % align) & (align - 1);
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if (extbuf != NULL)
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{
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/* Now we can check whether the buffer is large enough. */
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if (data_offset + npad + len > extlen)
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return -1;
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add_padding (extbuf, offset, npad);
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offset += npad;
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/* Now prepare the option itself. */
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struct ip6_opt *opt = (struct ip6_opt *) ((uint8_t *) extbuf + offset);
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opt->ip6o_type = type;
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opt->ip6o_len = len;
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*databufp = opt + 1;
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}
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else
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offset += npad;
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return offset + sizeof (struct ip6_opt) + len;
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}
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/* RFC 3542, 10.3
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This function returns the updated total length taking into account
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the final padding of the extension header to make it a multiple of
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8 bytes. If EXTBUF is not NULL the function also initializes the
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option by inserting a Pad1 or PadN option of the proper length. */
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int
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inet6_opt_finish (void *extbuf, socklen_t extlen, int offset)
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{
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/* Check minimum offset. */
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if (offset < sizeof (struct ip6_hbh))
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return -1;
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/* Required padding at the end. */
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int npad = (8 - (offset & 7)) & 7;
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if (extbuf != NULL)
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{
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/* Make sure the buffer is large enough. */
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if (offset + npad > extlen)
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return -1;
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add_padding (extbuf, offset, npad);
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}
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return offset + npad;
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}
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/* RFC 3542, 10.4
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This function inserts data items of various sizes in the data
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portion of the option. VAL should point to the data to be
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inserted. OFFSET specifies where in the data portion of the option
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the value should be inserted; the first byte after the option type
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and length is accessed by specifying an offset of zero. */
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int
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inet6_opt_set_val (void *databuf, int offset, void *val, socklen_t vallen)
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{
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memcpy ((uint8_t *) databuf + offset, val, vallen);
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return offset + vallen;
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}
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/* RFC 3542, 10.5
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This function parses received option extension headers returning
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the next option. EXTBUF and EXTLEN specifies the extension header.
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OFFSET should either be zero (for the first option) or the length
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returned by a previous call to 'inet6_opt_next' or
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'inet6_opt_find'. It specifies the position where to continue
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scanning the extension buffer. */
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int
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inet6_opt_next (void *extbuf, socklen_t extlen, int offset, uint8_t *typep,
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socklen_t *lenp, void **databufp)
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{
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if (offset == 0)
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offset = sizeof (struct ip6_hbh);
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else if (offset < sizeof (struct ip6_hbh))
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return -1;
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while (offset < extlen)
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{
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struct ip6_opt *opt = (struct ip6_opt *) ((uint8_t *) extbuf + offset);
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if (opt->ip6o_type == IP6OPT_PAD1)
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/* Single byte padding. */
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++offset;
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else if (opt->ip6o_type == IP6OPT_PADN)
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offset += sizeof (struct ip6_opt) + opt->ip6o_len;
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else
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{
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/* Check whether the option is valid. */
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offset += sizeof (struct ip6_opt) + opt->ip6o_len;
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if (offset > extlen)
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return -1;
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*typep = opt->ip6o_type;
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*lenp = opt->ip6o_len;
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*databufp = opt + 1;
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return offset;
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}
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}
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return -1;
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}
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/* RFC 3542, 10.6
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This function is similar to the previously described
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'inet6_opt_next' function, except this function lets the caller
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specify the option type to be searched for, instead of always
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returning the next option in the extension header. */
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int
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inet6_opt_find (void *extbuf, socklen_t extlen, int offset, uint8_t type,
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socklen_t *lenp, void **databufp)
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{
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if (offset == 0)
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offset = sizeof (struct ip6_hbh);
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else if (offset < sizeof (struct ip6_hbh))
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return -1;
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while (offset < extlen)
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{
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struct ip6_opt *opt = (struct ip6_opt *) ((uint8_t *) extbuf + offset);
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if (opt->ip6o_type == IP6OPT_PAD1)
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{
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/* Single byte padding. */
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++offset;
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if (type == IP6OPT_PAD1)
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{
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*lenp = 0;
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*databufp = (uint8_t *) extbuf + offset;
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return offset;
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}
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}
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else if (opt->ip6o_type != type)
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offset += sizeof (struct ip6_opt) + opt->ip6o_len;
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else
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{
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/* Check whether the option is valid. */
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offset += sizeof (struct ip6_opt) + opt->ip6o_len;
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if (offset > extlen)
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return -1;
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*lenp = opt->ip6o_len;
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*databufp = opt + 1;
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return offset;
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}
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}
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return -1;
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}
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/* RFC 3542, 10.7
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This function extracts data items of various sizes in the data
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portion of the option. */
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int
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inet6_opt_get_val (void *databuf, int offset, void *val, socklen_t vallen)
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{
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memcpy (val, (uint8_t *) databuf + offset, vallen);
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return offset + vallen;
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}
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