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/*
* Copyright (c) 2014 The TCPDUMP project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/* \summary: Loopback Protocol printer */
/*
* originally defined as the Ethernet Configuration Testing Protocol.
* specification:
* https://web.archive.org/web/20060919181108/http://www.mit.edu/people/jhawk/ctp.pdf
*/
#include <config.h>
#include "netdissect-stdinc.h"
#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"
#include "addrtoname.h"
#define LOOPBACK_REPLY 1
#define LOOPBACK_FWDDATA 2
static const struct tok fcode_str[] = {
{ LOOPBACK_REPLY, "Reply" },
{ LOOPBACK_FWDDATA, "Forward Data" },
{ 0, NULL }
};
static void
loopback_message_print(netdissect_options *ndo,
const u_char *cp, u_int len)
{
uint16_t function;
if (len < 2)
goto invalid;
/* function */
function = GET_LE_U_2(cp);
cp += 2;
len -= 2;
ND_PRINT(", %s", tok2str(fcode_str, " invalid (%u)", function));
switch (function) {
case LOOPBACK_REPLY:
if (len < 2)
goto invalid;
/* receipt number */
ND_PRINT(", receipt number %u", GET_LE_U_2(cp));
cp += 2;
len -= 2;
/* data */
ND_PRINT(", data (%u octets)", len);
ND_TCHECK_LEN(cp, len);
break;
case LOOPBACK_FWDDATA:
if (len < MAC_ADDR_LEN)
goto invalid;
/* forwarding address */
ND_PRINT(", forwarding address %s", GET_ETHERADDR_STRING(cp));
cp += MAC_ADDR_LEN;
len -= MAC_ADDR_LEN;
/* data */
ND_PRINT(", data (%u octets)", len);
ND_TCHECK_LEN(cp, len);
break;
default:
ND_TCHECK_LEN(cp, len);
break;
}
return;
invalid:
nd_print_invalid(ndo);
ND_TCHECK_LEN(cp, len);
}
void
loopback_print(netdissect_options *ndo,
const u_char *cp, u_int len)
{
uint16_t skipCount;
ndo->ndo_protocol = "loopback";
ND_PRINT("Loopback");
if (len < 2)
goto invalid;
/* skipCount */
skipCount = GET_LE_U_2(cp);
cp += 2;
len -= 2;
ND_PRINT(", skipCount %u", skipCount);
if (skipCount % 8)
ND_PRINT(" (bogus)");
if (skipCount > len)
goto invalid;
/* the octets to skip */
ND_TCHECK_LEN(cp, skipCount);
cp += skipCount;
len -= skipCount;
/* the first message to decode */
loopback_message_print(ndo, cp, len);
return;
invalid:
nd_print_invalid(ndo);
ND_TCHECK_LEN(cp, len);
}
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