1/*-
2 * Copyright (c) 2003, 2004 David Young.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. The name of David Young may not be used to endorse or promote
13 *    products derived from this software without specific prior
14 *    written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
18 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
19 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL DAVID
20 * YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
21 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
22 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
27 * OF SUCH DAMAGE.
28 */
29
30#ifdef HAVE_CONFIG_H
31#include "config.h"
32#endif
33
34#include <stdlib.h>
35#include <string.h>
36#include <tcpdump-stdinc.h>
37
38#include "cpack.h"
39#include "extract.h"
40
41u_int8_t *
42cpack_next_boundary(u_int8_t *buf, u_int8_t *p, size_t alignment)
43{
44	size_t misalignment = (size_t)(p - buf) % alignment;
45
46	if (misalignment == 0)
47		return p;
48
49	return p + (alignment - misalignment);
50}
51
52/* Advance to the next wordsize boundary. Return NULL if fewer than
53 * wordsize bytes remain in the buffer after the boundary.  Otherwise,
54 * return a pointer to the boundary.
55 */
56u_int8_t *
57cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize)
58{
59	u_int8_t *next;
60
61	/* Ensure alignment. */
62	next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize);
63
64	/* Too little space for wordsize bytes? */
65	if (next - cs->c_buf + wordsize > cs->c_len)
66		return NULL;
67
68	return next;
69}
70
71/* Advance by N bytes without returning them. */
72int
73cpack_advance(struct cpack_state *cs, const size_t toskip)
74{
75	/* No space left? */
76	if (cs->c_next - cs->c_buf + toskip > cs->c_len)
77		return -1;
78	cs->c_next += toskip;
79	return 0;
80}
81
82int
83cpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen)
84{
85	memset(cs, 0, sizeof(*cs));
86
87	cs->c_buf = buf;
88	cs->c_len = buflen;
89	cs->c_next = cs->c_buf;
90
91	return 0;
92}
93
94/* Unpack a 64-bit unsigned integer. */
95int
96cpack_uint64(struct cpack_state *cs, u_int64_t *u)
97{
98	u_int8_t *next;
99
100	if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
101		return -1;
102
103	*u = EXTRACT_LE_64BITS(next);
104
105	/* Move pointer past the u_int64_t. */
106	cs->c_next = next + sizeof(*u);
107	return 0;
108}
109
110/* Unpack a 32-bit unsigned integer. */
111int
112cpack_uint32(struct cpack_state *cs, u_int32_t *u)
113{
114	u_int8_t *next;
115
116	if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
117		return -1;
118
119	*u = EXTRACT_LE_32BITS(next);
120
121	/* Move pointer past the u_int32_t. */
122	cs->c_next = next + sizeof(*u);
123	return 0;
124}
125
126/* Unpack a 16-bit unsigned integer. */
127int
128cpack_uint16(struct cpack_state *cs, u_int16_t *u)
129{
130	u_int8_t *next;
131
132	if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
133		return -1;
134
135	*u = EXTRACT_LE_16BITS(next);
136
137	/* Move pointer past the u_int16_t. */
138	cs->c_next = next + sizeof(*u);
139	return 0;
140}
141
142/* Unpack an 8-bit unsigned integer. */
143int
144cpack_uint8(struct cpack_state *cs, u_int8_t *u)
145{
146	/* No space left? */
147	if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
148		return -1;
149
150	*u = *cs->c_next;
151
152	/* Move pointer past the u_int8_t. */
153	cs->c_next++;
154	return 0;
155}
156