The Tcpdump Group git mirrors - tcpdump/blob - cpack.c

   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 "netdissect-stdinc.h"
  37
  38 #include "netdissect.h"
  39 #include "extract.h"
  40
  41 #include "cpack.h"
  42
  43 const uint8_t *
  44 cpack_next_boundary(const uint8_t *buf, const uint8_t *p, size_t alignment)
  45 {
  46         size_t misalignment = (size_t)(p - buf) % alignment;
  47
  48         if (misalignment == 0)
  49                 return p;
  50
  51         return p + (alignment - misalignment);
  52 }
  53
  54 /* Advance to the next wordsize boundary. Return NULL if fewer than
  55  * wordsize bytes remain in the buffer after the boundary.  Otherwise,
  56  * return a pointer to the boundary.
  57  */
  58 const uint8_t *
  59 cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize)
  60 {
  61         const uint8_t *next;
  62
  63         /* Ensure alignment. */
  64         next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize);
  65
  66         /* Too little space for wordsize bytes? */
  67         if (next - cs->c_buf + wordsize > cs->c_len)
  68                 return NULL;
  69
  70         return next;
  71 }
  72
  73 /* Advance by N bytes without returning them. */
  74 int
  75 cpack_advance(struct cpack_state *cs, const size_t toskip)
  76 {
  77         /* No space left? */
  78         if (cs->c_next - cs->c_buf + toskip > cs->c_len)
  79                 return -1;
  80         cs->c_next += toskip;
  81         return 0;
  82 }
  83
  84 int
  85 cpack_init(struct cpack_state *cs, const uint8_t *buf, size_t buflen)
  86 {
  87         memset(cs, 0, sizeof(*cs));
  88
  89         cs->c_buf = buf;
  90         cs->c_len = buflen;
  91         cs->c_next = cs->c_buf;
  92
  93         return 0;
  94 }
  95
  96 /* Unpack a 64-bit unsigned integer. */
  97 int
  98 cpack_uint64(netdissect_options *ndo, struct cpack_state *cs, uint64_t *u)
  99 {
 100         const uint8_t *next;
 101
 102         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 103                 return -1;
 104
 105         *u = GET_LE_U_8(next);
 106
 107         /* Move pointer past the uint64_t. */
 108         cs->c_next = next + sizeof(*u);
 109         return 0;
 110 }
 111
 112 /* Unpack a 64-bit signed integer. */
 113 int
 114 cpack_int64(netdissect_options *ndo, struct cpack_state *cs, int64_t *u)
 115 {
 116         const uint8_t *next;
 117
 118         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 119                 return -1;
 120
 121         *u = GET_LE_S_8(next);
 122
 123         /* Move pointer past the int64_t. */
 124         cs->c_next = next + sizeof(*u);
 125         return 0;
 126 }
 127
 128 /* Unpack a 32-bit unsigned integer. */
 129 int
 130 cpack_uint32(netdissect_options *ndo, struct cpack_state *cs, uint32_t *u)
 131 {
 132         const uint8_t *next;
 133
 134         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 135                 return -1;
 136
 137         *u = GET_LE_U_4(next);
 138
 139         /* Move pointer past the uint32_t. */
 140         cs->c_next = next + sizeof(*u);
 141         return 0;
 142 }
 143
 144 /* Unpack a 32-bit signed integer. */
 145 int
 146 cpack_int32(netdissect_options *ndo, struct cpack_state *cs, int32_t *u)
 147 {
 148         const uint8_t *next;
 149
 150         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 151                 return -1;
 152
 153         *u = GET_LE_S_4(next);
 154
 155         /* Move pointer past the int32_t. */
 156         cs->c_next = next + sizeof(*u);
 157         return 0;
 158 }
 159
 160 /* Unpack a 16-bit unsigned integer. */
 161 int
 162 cpack_uint16(netdissect_options *ndo, struct cpack_state *cs, uint16_t *u)
 163 {
 164         const uint8_t *next;
 165
 166         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 167                 return -1;
 168
 169         *u = GET_LE_U_2(next);
 170
 171         /* Move pointer past the uint16_t. */
 172         cs->c_next = next + sizeof(*u);
 173         return 0;
 174 }
 175
 176 /* Unpack a 16-bit signed integer. */
 177 int
 178 cpack_int16(netdissect_options *ndo, struct cpack_state *cs, int16_t *u)
 179 {
 180         const uint8_t *next;
 181
 182         if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
 183                 return -1;
 184
 185         *u = GET_LE_S_2(next);
 186
 187         /* Move pointer past the int16_t. */
 188         cs->c_next = next + sizeof(*u);
 189         return 0;
 190 }
 191
 192 /* Unpack an 8-bit unsigned integer. */
 193 int
 194 cpack_uint8(netdissect_options *ndo, struct cpack_state *cs, uint8_t *u)
 195 {
 196         /* No space left? */
 197         if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
 198                 return -1;
 199
 200         *u = GET_U_1(cs->c_next);
 201
 202         /* Move pointer past the uint8_t. */
 203         cs->c_next++;
 204         return 0;
 205 }
 206
 207 /* Unpack an 8-bit signed integer. */
 208 int
 209 cpack_int8(netdissect_options *ndo, struct cpack_state *cs, int8_t *u)
 210 {
 211         /* No space left? */
 212         if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len)
 213                 return -1;
 214
 215         *u = GET_S_1(cs->c_next);
 216
 217         /* Move pointer past the int8_t. */
 218         cs->c_next++;
 219         return 0;
 220 }