/*
 * Copyright (C) 2001 Julian Cowley
 * 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.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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: Cisco Hot Standby Router Protocol (HSRP) printer */

/* specification: RFC 2281 for version 1 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "netdissect-stdinc.h"

#include "netdissect.h"
#include "addrtoname.h"
#include "extract.h"

/* HSRP op code types. */
static const char *op_code_str[] = {
	"hello",
	"coup",
	"resign"
};

/* HSRP states and associated names. */
static const struct tok states[] = {
	{  0, "initial" },
	{  1, "learn" },
	{  2, "listen" },
	{  4, "speak" },
	{  8, "standby" },
	{ 16, "active" },
	{  0, NULL }
};

/*
 * RFC 2281:
 *
 *  0                   1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |   Version     |   Op Code     |     State     |   Hellotime   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |   Holdtime    |   Priority    |     Group     |   Reserved    |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Authentication  Data                     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Authentication  Data                     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Virtual IP Address                       |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

#define HSRP_AUTH_SIZE	8

/* HSRP protocol header. */
struct hsrp {
	nd_uint8_t	hsrp_version;
	nd_uint8_t	hsrp_op_code;
	nd_uint8_t	hsrp_state;
	nd_uint8_t	hsrp_hellotime;
	nd_uint8_t	hsrp_holdtime;
	nd_uint8_t	hsrp_priority;
	nd_uint8_t	hsrp_group;
	nd_uint8_t	hsrp_reserved;
	nd_byte		hsrp_authdata[HSRP_AUTH_SIZE];
	nd_ipv4		hsrp_virtaddr;
};

void
hsrp_print(netdissect_options *ndo, const u_char *bp, u_int len)
{
	const struct hsrp *hp = (const struct hsrp *) bp;
	uint8_t version;

	ndo->ndo_protocol = "hsrp";
	version = GET_U_1(hp->hsrp_version);
	ND_PRINT("HSRPv%u", version);
	if (version != 0)
		return;
	ND_PRINT("-");
	ND_PRINT("%s ",
		 tok2strary(op_code_str, "unknown (%u)", GET_U_1(hp->hsrp_op_code)));
	ND_PRINT("%u: ", len);
	ND_PRINT("state=%s ",
		 tok2str(states, "Unknown (%u)", GET_U_1(hp->hsrp_state)));
	ND_PRINT("group=%u ", GET_U_1(hp->hsrp_group));
	if (GET_U_1(hp->hsrp_reserved) != 0) {
		ND_PRINT("[reserved=%u!] ", GET_U_1(hp->hsrp_reserved));
	}
	ND_PRINT("addr=%s", GET_IPADDR_STRING(hp->hsrp_virtaddr));
	if (ndo->ndo_vflag) {
		ND_PRINT(" hellotime=");
		unsigned_relts_print(ndo, GET_U_1(hp->hsrp_hellotime));
		ND_PRINT(" holdtime=");
		unsigned_relts_print(ndo, GET_U_1(hp->hsrp_holdtime));
		ND_PRINT(" priority=%u", GET_U_1(hp->hsrp_priority));
		ND_PRINT(" auth=\"");
		/*
		 * RFC 2281 Section 5.1 does not specify the encoding of
		 * Authentication Data explicitly, but zero padding can be
		 * inferred from the "recommended default value".
		 */
		(void)nd_print(ndo, hp->hsrp_authdata, hp->hsrp_authdata + HSRP_AUTH_SIZE);
		ND_PRINT("\"");
	}
}
