epan/crc32-tvb.c

   1 /* crc32-tvb.c
   2  * CRC-32 tvbuff routines
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  *
  24  * Credits:
  25  *
  26  * Table from Solomon Peachy
  27  * Routine from Chris Waters
  28  */
  29
  30 #include "config.h"
  31
  32 #include <glib.h>
  33 #include <epan/tvbuff.h>
  34 #include <wsutil/crc32.h>
  35 #include <epan/crc32-tvb.h>
  36
  37
  38 guint32
  39 crc32_ccitt_tvb(tvbuff_t *tvb, guint len)
  40 {
  41         const guint8* buf;
  42
  43         tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */
  44         buf = tvb_get_ptr(tvb, 0, len);
  45
  46         return ( crc32_ccitt_seed(buf, len, CRC32_CCITT_SEED) );
  47 }
  48
  49 guint32
  50 crc32_ccitt_tvb_offset(tvbuff_t *tvb, guint offset, guint len)
  51 {
  52         const guint8* buf;
  53
  54         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
  55         buf = tvb_get_ptr(tvb, offset, len);
  56
  57         return ( crc32_ccitt(buf, len) );
  58 }
  59
  60 guint32
  61 crc32_ccitt_tvb_seed(tvbuff_t *tvb, guint len, guint32 seed)
  62 {
  63         const guint8* buf;
  64
  65         tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */
  66         buf = tvb_get_ptr(tvb, 0, len);
  67
  68         return ( crc32_ccitt_seed(buf, len, seed) );
  69 }
  70
  71 guint32
  72 crc32_ccitt_tvb_offset_seed(tvbuff_t *tvb, guint offset, guint len,
  73                             guint32 seed)
  74 {
  75         const guint8* buf;
  76
  77         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
  78         buf = tvb_get_ptr(tvb, offset, len);
  79
  80         return ( crc32_ccitt_seed(buf, len, seed) );
  81 }
  82
  83 /*
  84  * IEEE 802.x version (Ethernet and 802.11, at least) - byte-swap
  85  * the result of "crc32()".
  86  *
  87  * XXX - does this mean we should fetch the Ethernet and 802.11
  88  * FCS with "tvb_get_letohl()" rather than "tvb_get_ntohl()",
  89  * or is fetching it big-endian and byte-swapping the CRC done
  90  * to cope with 802.x sending stuff out in reverse bit order?
  91  */
  92 guint32
  93 crc32_802_tvb(tvbuff_t *tvb, guint len)
  94 {
  95         guint32 c_crc;
  96
  97         c_crc = crc32_ccitt_tvb(tvb, len);
  98
  99         /* Byte reverse. */
 100         c_crc = GUINT32_SWAP_LE_BE(c_crc);
 101
 102         return ( c_crc );
 103 }
 104
 105 guint32
 106 crc32_mpeg2_tvb_offset_seed(tvbuff_t *tvb, guint offset,
 107                                        guint len, guint32 seed)
 108 {
 109         const guint8* buf;
 110
 111         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
 112         buf = tvb_get_ptr(tvb, offset, len);
 113
 114         return ( crc32_mpeg2_seed(buf, len, seed) );
 115 }
 116
 117 guint32
 118 crc32_mpeg2_tvb(tvbuff_t *tvb, guint len)
 119 {
 120     return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, CRC32_MPEG2_SEED) );
 121 }
 122
 123 guint32
 124 crc32_mpeg2_tvb_offset(tvbuff_t *tvb, guint offset, guint len)
 125 {
 126     return ( crc32_mpeg2_tvb_offset_seed(tvb, offset, len, CRC32_MPEG2_SEED) );
 127 }
 128
 129 guint32
 130 crc32_mpeg2_tvb_seed(tvbuff_t *tvb, guint len, guint32 seed)
 131 {
 132     return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, seed) );
 133 }
 134
 135 guint32 crc32_0x0AA725CF_tvb_offset_seed(tvbuff_t *tvb,
 136                                             guint offset, guint len, guint32 seed)
 137 {
 138     const guint8 *buf;
 139
 140     tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
 141     buf = tvb_get_ptr(tvb, offset, len);
 142
 143     return crc32_0x0AA725CF_seed(buf, len, seed);
 144 }