forked from osmocom/wireshark
108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
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/* crc32-tvb.c
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* CRC-32 tvbuff routines
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*
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* $Id$
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Credits:
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*
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* Table from Solomon Peachy
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* Routine from Chris Waters
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <glib.h>
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#include <epan/tvbuff.h>
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#include <wsutil/crc32.h>
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guint32
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crc32_ccitt_tvb(tvbuff_t *tvb, guint len)
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{
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const guint8* buf;
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tvb_ensure_bytes_exist(tvb, 0, len); /* len == -1 not allowed */
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buf = tvb_get_ptr(tvb, 0, len);
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return ( crc32_ccitt_seed(buf, len, CRC32_CCITT_SEED) );
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}
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guint32
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crc32_ccitt_tvb_offset(tvbuff_t *tvb, guint offset, guint len)
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{
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const guint8* buf;
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tvb_ensure_bytes_exist(tvb, offset, len); /* len == -1 not allowed */
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buf = tvb_get_ptr(tvb, offset, len);
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return ( crc32_ccitt(buf, len) );
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}
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guint32
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crc32_ccitt_tvb_seed(tvbuff_t *tvb, guint len, guint32 seed)
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{
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const guint8* buf;
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tvb_ensure_bytes_exist(tvb, 0, len); /* len == -1 not allowed */
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buf = tvb_get_ptr(tvb, 0, len);
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return ( crc32_ccitt_seed(buf, len, seed) );
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}
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guint32
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crc32_ccitt_tvb_offset_seed(tvbuff_t *tvb, guint offset, guint len,
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guint32 seed)
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{
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const guint8* buf;
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tvb_ensure_bytes_exist(tvb, offset, len); /* len == -1 not allowed */
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buf = tvb_get_ptr(tvb, offset, len);
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return ( crc32_ccitt_seed(buf, len, seed) );
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}
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/*
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* IEEE 802.x version (Ethernet and 802.11, at least) - byte-swap
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* the result of "crc32()".
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*
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* XXX - does this mean we should fetch the Ethernet and 802.11
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* FCS with "tvb_get_letohl()" rather than "tvb_get_ntohl()",
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* or is fetching it big-endian and byte-swapping the CRC done
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* to cope with 802.x sending stuff out in reverse bit order?
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*/
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guint32
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crc32_802_tvb(tvbuff_t *tvb, guint len)
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{
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guint32 c_crc;
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c_crc = crc32_ccitt_tvb(tvb, len);
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/* Byte reverse. */
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c_crc = ((unsigned char)(c_crc>>0)<<24) |
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((unsigned char)(c_crc>>8)<<16) |
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((unsigned char)(c_crc>>16)<<8) |
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((unsigned char)(c_crc>>24)<<0);
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return ( c_crc );
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}
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