/*
 * Copyright (c) 2009 Lukas Mejdrech
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup icmp
 *  @{
 */

/** @file
 *  ICMP header definition.
 *  Based on the RFC~792.
 */

#ifndef __NET_ICMP_HEADER_H__
#define __NET_ICMP_HEADER_H__

#include <sys/types.h>

#include "../../include/in.h"
#include "../../include/icmp_codes.h"

/** ICMP header size in bytes.
 */
#define ICMP_HEADER_SIZE			sizeof( icmp_header_t )

/** Type definition of the echo specific data.
 *  @see icmp_echo
 */
typedef struct icmp_echo	icmp_echo_t;

/** Type definition of the echo specific data pointer.
 *  @see icmp_echo
 */
typedef icmp_echo_t *		icmp_echo_ref;

/** Echo specific data.
 */
struct icmp_echo{
	/** Message idintifier.
	 */
	icmp_param_t	identifier;
	/** Message sequence number.
	 */
	icmp_param_t	sequence_number;
} __attribute__ ((packed));

/** Type definition of the internet control message header.
 *  @see icmp_header
 */
typedef struct icmp_header	icmp_header_t;

/** Type definition of the internet control message header pointer.
 *  @see icmp_header
 */
typedef icmp_header_t *		icmp_header_ref;

/** Internet control message header.
 */
struct icmp_header{
	/** The type of the message.
	 */
	uint8_t	type;
	/** The error code for the datagram reported by the ICMP message.
	 *  The interpretation is dependent on the message type.
	 */
	uint8_t	code;
	/** The checksum is the 16-bit ones's complement of the one's complement sum of the ICMP message starting with the ICMP Type.
     *  For computing the checksum, the checksum field should be zero.
	 *  If the checksum does not match the contents, the datagram is discarded.
	 */
	uint16_t	checksum;
	/** Message specific data.
	 */
	union{
		/** Echo specific data.
		 */
		icmp_echo_t 		echo;
		/** Proposed gateway value.
		 */
		in_addr_t			gateway;
		/** Fragmentation needed specific data.
		 */
		struct{
			/** Reserved field.
			 *  Must be zero.
			 */
			icmp_param_t	reserved;
			/** Proposed MTU.
			 */
			icmp_param_t	mtu;
		} frag;
		/** Parameter problem specific data.
		 */
		struct{
			/** Problem pointer.
			 */
			icmp_param_t	pointer;
			/** Reserved field.
			 *  Must be zero.
			 */
			icmp_param_t	reserved;
		} param;
	} un;
} __attribute__ ((packed));

#endif

/** @}
 */