Move tcpdump-3.9/ to tcpdump/. No need for a versioned dir.
[dragonfly.git] / contrib / tcpdump / cpack.c
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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
41static u_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 */
56static u_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
71int
72cpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen)
73{
74 memset(cs, 0, sizeof(*cs));
75
76 cs->c_buf = buf;
77 cs->c_len = buflen;
78 cs->c_next = cs->c_buf;
79
80 return 0;
81}
82
83/* Unpack a 64-bit unsigned integer. */
84int
85cpack_uint64(struct cpack_state *cs, u_int64_t *u)
86{
87 u_int8_t *next;
88
89 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
90 return -1;
91
92 *u = EXTRACT_LE_64BITS(next);
93
94 /* Move pointer past the u_int64_t. */
95 cs->c_next = next + sizeof(*u);
96 return 0;
97}
98
99/* Unpack a 32-bit unsigned integer. */
100int
101cpack_uint32(struct cpack_state *cs, u_int32_t *u)
102{
103 u_int8_t *next;
104
105 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
106 return -1;
107
108 *u = EXTRACT_LE_32BITS(next);
109
110 /* Move pointer past the u_int32_t. */
111 cs->c_next = next + sizeof(*u);
112 return 0;
113}
114
115/* Unpack a 16-bit unsigned integer. */
116int
117cpack_uint16(struct cpack_state *cs, u_int16_t *u)
118{
119 u_int8_t *next;
120
121 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
122 return -1;
123
124 *u = EXTRACT_LE_16BITS(next);
125
126 /* Move pointer past the u_int16_t. */
127 cs->c_next = next + sizeof(*u);
128 return 0;
129}
130
131/* Unpack an 8-bit unsigned integer. */
132int
133cpack_uint8(struct cpack_state *cs, u_int8_t *u)
134{
135 /* No space left? */
136 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
137 return -1;
138
139 *u = *cs->c_next;
140
141 /* Move pointer past the u_int8_t. */
142 cs->c_next++;
143 return 0;
144}