mirror of
https://github.com/the-tcpdump-group/tcpdump.git
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145 lines
3.7 KiB
C
145 lines
3.7 KiB
C
/*-
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* Copyright (c) 2003, 2004 David Young. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of David Young may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DAVID
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* YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include <tcpdump-stdinc.h>
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#include "cpack.h"
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#include "extract.h"
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static u_int8_t *
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cpack_next_boundary(u_int8_t *buf, u_int8_t *p, size_t alignment)
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{
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size_t misalignment = (size_t)(p - buf) % alignment;
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if (misalignment == 0)
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return p;
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return p + (alignment - misalignment);
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}
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/* Advance to the next wordsize boundary. Return NULL if fewer than
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* wordsize bytes remain in the buffer after the boundary. Otherwise,
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* return a pointer to the boundary.
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*/
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static u_int8_t *
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cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize)
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{
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u_int8_t *next;
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/* Ensure alignment. */
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next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize);
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/* Too little space for wordsize bytes? */
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if (next - cs->c_buf + wordsize > cs->c_len)
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return NULL;
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return next;
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}
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int
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cpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen)
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{
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memset(cs, 0, sizeof(*cs));
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cs->c_buf = buf;
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cs->c_len = buflen;
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cs->c_next = cs->c_buf;
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return 0;
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}
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/* Unpack a 64-bit unsigned integer. */
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int
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cpack_uint64(struct cpack_state *cs, u_int64_t *u)
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{
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u_int8_t *next;
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if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
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return -1;
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*u = EXTRACT_LE_64BITS(next);
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/* Move pointer past the u_int64_t. */
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cs->c_next = next + sizeof(*u);
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return 0;
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}
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/* Unpack a 32-bit unsigned integer. */
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int
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cpack_uint32(struct cpack_state *cs, u_int32_t *u)
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{
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u_int8_t *next;
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if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
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return -1;
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*u = EXTRACT_LE_32BITS(next);
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/* Move pointer past the u_int32_t. */
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cs->c_next = next + sizeof(*u);
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return 0;
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}
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/* Unpack a 16-bit unsigned integer. */
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int
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cpack_uint16(struct cpack_state *cs, u_int16_t *u)
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{
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u_int8_t *next;
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if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
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return -1;
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*u = EXTRACT_LE_16BITS(next);
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/* Move pointer past the u_int16_t. */
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cs->c_next = next + sizeof(*u);
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return 0;
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}
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/* Unpack an 8-bit unsigned integer. */
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int
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cpack_uint8(struct cpack_state *cs, u_int8_t *u)
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{
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/* No space left? */
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if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
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return -1;
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*u = *cs->c_next;
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/* Move pointer past the u_int8_t. */
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cs->c_next++;
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return 0;
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}
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