1/*	$OpenBSD: print-carp.c,v 1.6 2009/10/27 23:59:55 deraadt Exp $	*/
2
3/*
4 * Copyright (c) 2000 William C. Fenner.
5 *                All rights reserved.
6 *
7 * Kevin Steves <ks@hp.se> July 2000
8 * Modified to:
9 * - print version, type string and packet length
10 * - print IP address count if > 1 (-v)
11 * - verify checksum (-v)
12 * - print authentication string (-v)
13 *
14 * Copyright (c) 2011 Advanced Computing Technologies
15 * George V. Neille-Neil
16 *
17 * Modified to:
18 * - work correctly with CARP
19 * - compile into the latest tcpdump
20 * - print out the counter
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that: (1) source code
24 * distributions retain the above copyright notice and this paragraph
25 * in its entirety, and (2) distributions including binary code include
26 * the above copyright notice and this paragraph in its entirety in
27 * the documentation or other materials provided with the distribution.
28 * The name of William C. Fenner may not be used to endorse or
29 * promote products derived from this software without specific prior
30 * written permission.  THIS SOFTWARE IS PROVIDED ``AS IS'' AND
31 * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
32 * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
33 * FOR A PARTICULAR PURPOSE.
34 *
35 */
36
37/* \summary: Common Address Redundancy Protocol (CARP) printer */
38
39#ifdef HAVE_CONFIG_H
40#include <config.h>
41#endif
42
43#include "netdissect-stdinc.h"
44
45#include "netdissect.h" /* for checksum structure and functions */
46#include "extract.h"
47
48void
49carp_print(netdissect_options *ndo, const u_char *bp, u_int len, u_int ttl)
50{
51	u_int version, type;
52	const char *type_s;
53
54	ndo->ndo_protocol = "carp";
55	version = (GET_U_1(bp) & 0xf0) >> 4;
56	type = GET_U_1(bp) & 0x0f;
57	if (type == 1)
58		type_s = "advertise";
59	else
60		type_s = "unknown";
61	ND_PRINT("CARPv%u-%s %u: ", version, type_s, len);
62	if (ttl != 255)
63		ND_PRINT("[ttl=%u!] ", ttl);
64	if (version != 2 || type != 1)
65		return;
66	ND_PRINT("vhid=%u advbase=%u advskew=%u authlen=%u ",
67	    GET_U_1(bp + 1), GET_U_1(bp + 5), GET_U_1(bp + 2),
68	    GET_U_1(bp + 3));
69	if (ndo->ndo_vflag) {
70		struct cksum_vec vec[1];
71		vec[0].ptr = (const uint8_t *)bp;
72		vec[0].len = len;
73		if (ND_TTEST_LEN(bp, len) && in_cksum(vec, 1))
74			ND_PRINT(" (bad carp cksum %x!)",
75				GET_BE_U_2(bp + 6));
76	}
77	ND_PRINT("counter=%" PRIu64, GET_BE_U_8(bp + 8));
78}
79