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, register const u_char *bp, register u_int len, int ttl)
50{
51	int version, type;
52	const char *type_s;
53
54	ND_TCHECK(bp[0]);
55	version = (bp[0] & 0xf0) >> 4;
56	type = bp[0] & 0x0f;
57	if (type == 1)
58		type_s = "advertise";
59	else
60		type_s = "unknown";
61	ND_PRINT((ndo, "CARPv%d-%s %d: ", version, type_s, len));
62	if (ttl != 255)
63		ND_PRINT((ndo, "[ttl=%d!] ", ttl));
64	if (version != 2 || type != 1)
65		return;
66	ND_TCHECK(bp[2]);
67	ND_TCHECK(bp[5]);
68	ND_PRINT((ndo, "vhid=%d advbase=%d advskew=%d authlen=%d ",
69	    bp[1], bp[5], bp[2], bp[3]));
70	if (ndo->ndo_vflag) {
71		struct cksum_vec vec[1];
72		vec[0].ptr = (const uint8_t *)bp;
73		vec[0].len = len;
74		if (ND_TTEST2(bp[0], len) && in_cksum(vec, 1))
75			ND_PRINT((ndo, " (bad carp cksum %x!)",
76				EXTRACT_16BITS(&bp[6])));
77	}
78	ND_PRINT((ndo, "counter=%" PRIu64, EXTRACT_64BITS(&bp[8])));
79
80	return;
81trunc:
82	ND_PRINT((ndo, "[|carp]"));
83}
84