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 #define NETDISSECT_REWORKED
31 #ifdef HAVE_CONFIG_H
32 #include "config.h"
33 #endif
34
35 #include <stdlib.h>
36 #include <string.h>
37 #include <tcpdump-stdinc.h>
38
39 #include "cpack.h"
40 #include "extract.h"
41
42 uint8_t *
cpack_next_boundary(uint8_t * buf,uint8_t * p,size_t alignment)43 cpack_next_boundary(uint8_t *buf, uint8_t *p, size_t alignment)
44 {
45 size_t misalignment = (size_t)(p - buf) % alignment;
46
47 if (misalignment == 0)
48 return p;
49
50 return p + (alignment - misalignment);
51 }
52
53 /* Advance to the next wordsize boundary. Return NULL if fewer than
54 * wordsize bytes remain in the buffer after the boundary. Otherwise,
55 * return a pointer to the boundary.
56 */
57 uint8_t *
cpack_align_and_reserve(struct cpack_state * cs,size_t wordsize)58 cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize)
59 {
60 uint8_t *next;
61
62 /* Ensure alignment. */
63 next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize);
64
65 /* Too little space for wordsize bytes? */
66 if (next - cs->c_buf + wordsize > cs->c_len)
67 return NULL;
68
69 return next;
70 }
71
72 /* Advance by N bytes without returning them. */
73 int
cpack_advance(struct cpack_state * cs,const size_t toskip)74 cpack_advance(struct cpack_state *cs, const size_t toskip)
75 {
76 /* No space left? */
77 if (cs->c_next - cs->c_buf + toskip > cs->c_len)
78 return -1;
79 cs->c_next += toskip;
80 return 0;
81 }
82
83 int
cpack_init(struct cpack_state * cs,uint8_t * buf,size_t buflen)84 cpack_init(struct cpack_state *cs, uint8_t *buf, size_t buflen)
85 {
86 memset(cs, 0, sizeof(*cs));
87
88 cs->c_buf = buf;
89 cs->c_len = buflen;
90 cs->c_next = cs->c_buf;
91
92 return 0;
93 }
94
95 /* Unpack a 64-bit unsigned integer. */
96 int
cpack_uint64(struct cpack_state * cs,uint64_t * u)97 cpack_uint64(struct cpack_state *cs, uint64_t *u)
98 {
99 uint8_t *next;
100
101 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
102 return -1;
103
104 *u = EXTRACT_LE_64BITS(next);
105
106 /* Move pointer past the uint64_t. */
107 cs->c_next = next + sizeof(*u);
108 return 0;
109 }
110
111 /* Unpack a 32-bit unsigned integer. */
112 int
cpack_uint32(struct cpack_state * cs,uint32_t * u)113 cpack_uint32(struct cpack_state *cs, uint32_t *u)
114 {
115 uint8_t *next;
116
117 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
118 return -1;
119
120 *u = EXTRACT_LE_32BITS(next);
121
122 /* Move pointer past the uint32_t. */
123 cs->c_next = next + sizeof(*u);
124 return 0;
125 }
126
127 /* Unpack a 16-bit unsigned integer. */
128 int
cpack_uint16(struct cpack_state * cs,uint16_t * u)129 cpack_uint16(struct cpack_state *cs, uint16_t *u)
130 {
131 uint8_t *next;
132
133 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
134 return -1;
135
136 *u = EXTRACT_LE_16BITS(next);
137
138 /* Move pointer past the uint16_t. */
139 cs->c_next = next + sizeof(*u);
140 return 0;
141 }
142
143 /* Unpack an 8-bit unsigned integer. */
144 int
cpack_uint8(struct cpack_state * cs,uint8_t * u)145 cpack_uint8(struct cpack_state *cs, uint8_t *u)
146 {
147 /* No space left? */
148 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
149 return -1;
150
151 *u = *cs->c_next;
152
153 /* Move pointer past the uint8_t. */
154 cs->c_next++;
155 return 0;
156 }
157