epan/crc32-tvb.c

   1 /* crc32-tvb.c
   2  * CRC-32 tvbuff routines
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  *
  10  * Credits:
  11  *
  12  * Table from Solomon Peachy
  13  * Routine from Chris Waters
  14  */
  15
  16 #include "config.h"
  17
  18 #include <glib.h>
  19 #include <epan/tvbuff.h>
  20 #include <wsutil/crc32.h>
  21 #include <epan/crc32-tvb.h>
  22
  23
  24 uint32_t
  25 crc32_ccitt_tvb(tvbuff_t *tvb, unsigned len)
  26 {
  27         const uint8_t* buf;
  28
  29         tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */
  30         buf = tvb_get_ptr(tvb, 0, len);
  31
  32         return ( crc32_ccitt_seed(buf, len, CRC32_CCITT_SEED) );
  33 }
  34
  35 uint32_t
  36 crc32_ccitt_tvb_offset(tvbuff_t *tvb, unsigned offset, unsigned len)
  37 {
  38         const uint8_t* buf;
  39
  40         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
  41         buf = tvb_get_ptr(tvb, offset, len);
  42
  43         return ( crc32_ccitt(buf, len) );
  44 }
  45
  46 uint32_t
  47 crc32_ccitt_tvb_seed(tvbuff_t *tvb, unsigned len, uint32_t seed)
  48 {
  49         const uint8_t* buf;
  50
  51         tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */
  52         buf = tvb_get_ptr(tvb, 0, len);
  53
  54         return ( crc32_ccitt_seed(buf, len, seed) );
  55 }
  56
  57 uint32_t
  58 crc32_ccitt_tvb_offset_seed(tvbuff_t *tvb, unsigned offset, unsigned len,
  59                             uint32_t seed)
  60 {
  61         const uint8_t* buf;
  62
  63         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
  64         buf = tvb_get_ptr(tvb, offset, len);
  65
  66         return ( crc32_ccitt_seed(buf, len, seed) );
  67 }
  68
  69 uint32_t
  70 crc32c_tvb_offset_calculate(tvbuff_t *tvb, unsigned offset, unsigned len, uint32_t seed)
  71 {
  72         const uint8_t* buf;
  73
  74         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
  75         buf = tvb_get_ptr(tvb, offset, len);
  76
  77         return ( crc32c_calculate(buf, len, seed) );
  78 }
  79
  80 /*
  81  * IEEE 802.x version (Ethernet and 802.11, at least) - byte-swap
  82  * the result of "crc32()".
  83  *
  84  * XXX - does this mean we should fetch the Ethernet and 802.11
  85  * FCS with "tvb_get_letohl()" rather than "tvb_get_ntohl()",
  86  * or is fetching it big-endian and byte-swapping the CRC done
  87  * to cope with 802.x sending stuff out in reverse bit order?
  88  */
  89 uint32_t
  90 crc32_802_tvb(tvbuff_t *tvb, unsigned len)
  91 {
  92         uint32_t c_crc;
  93
  94         c_crc = crc32_ccitt_tvb(tvb, len);
  95
  96         /* Byte reverse. */
  97         c_crc = GUINT32_SWAP_LE_BE(c_crc);
  98
  99         return ( c_crc );
 100 }
 101
 102 uint32_t
 103 crc32_mpeg2_tvb_offset_seed(tvbuff_t *tvb, unsigned offset,
 104                             unsigned len, uint32_t seed)
 105 {
 106         const uint8_t* buf;
 107
 108         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
 109         buf = tvb_get_ptr(tvb, offset, len);
 110
 111         return ( crc32_mpeg2_seed(buf, len, seed) );
 112 }
 113
 114 uint32_t
 115 crc32_mpeg2_tvb(tvbuff_t *tvb, unsigned len)
 116 {
 117         return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, CRC32_MPEG2_SEED) );
 118 }
 119
 120 uint32_t
 121 crc32_mpeg2_tvb_offset(tvbuff_t *tvb, unsigned offset, unsigned len)
 122 {
 123         return ( crc32_mpeg2_tvb_offset_seed(tvb, offset, len, CRC32_MPEG2_SEED) );
 124 }
 125
 126 uint32_t
 127 crc32_mpeg2_tvb_seed(tvbuff_t *tvb, unsigned len, uint32_t seed)
 128 {
 129         return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, seed) );
 130 }
 131
 132 uint32_t crc32_0x0AA725CF_tvb_offset_seed(tvbuff_t *tvb,
 133                                          unsigned offset, unsigned len, uint32_t seed)
 134 {
 135         const uint8_t *buf;
 136
 137         tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */
 138         buf = tvb_get_ptr(tvb, offset, len);
 139
 140         return crc32_0x0AA725CF_seed(buf, len, seed);
 141 }
 142
 143 /*
 144  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 145  *
 146  * Local variables:
 147  * c-basic-offset: 8
 148  * tab-width: 8
 149  * indent-tabs-mode: t
 150  * End:
 151  *
 152  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 153  * :indentSize=8:tabSize=8:noTabs=false:
 154  */