igmp_deserialize_message.c

路由器协议平台igmp协议设计实现源码。

/*
 $Log:: /OEM Source Code/igmp/igmp_deserialize_message.c                                           $
 * 
 * 1     4/23/98 9:53p Release Engineer
 * Initial release
 * IGMP v4.1.0
 */
/************************************************************************/
/*  Copyright (C) 1997-1998 RouterWare, Inc.                            */
/*  Unpublished - rights reserved under the Copyright Laws of the       */
/*  United States.  Use, duplication, or disclosure by the              */
/*  Government is subject to restrictions as set forth in               */
/*  subparagraph (c)(1)(ii) of the Rights in Technical Data and         */
/*  Computer Software clause at 252.227-7013.                           */
/*  RouterWare, Inc., 3961 MacArthur Blvd. Suite 212, Newport Beach, CA */
/************************************************************************/
#include <stdlib.h>
#include "igmp.h"
#include "igmp_packet.h"
/********************************************************************************************/
static enum BOOLEAN igmp_received_valid_ip_packet (IP_PARAMETERS *sptr_ip_parameters);
static enum BOOLEAN igmp_received_valid_message (IGMP_PAYLOAD *sptr_igmp_payload, UINT size_of_igmp_payload);
/********************************************************************************************/
IGMP_MESSAGE *igmp_deserialize_received_message (IP_PARAMETERS *sptr_ip_parameters, void *sptr_igmp_received_packet, UINT igmp_packet_size)
{
	IGMP_MESSAGE *sptr_igmp_message;
	IGMP_PAYLOAD *sptr_igmp_payload;

	if (igmp_received_valid_ip_packet (sptr_ip_parameters) == FALSE)
		{
		return (NULL);
		}
	
	sptr_igmp_payload = (IGMP_PAYLOAD *)(&(((IP_PACKET *)sptr_igmp_received_packet)->options_or_data.data) + sptr_ip_parameters->options_length);

	if (igmp_received_valid_message (sptr_igmp_payload, igmp_packet_size) == FALSE)
		{
		return (NULL);
		}

	sptr_igmp_message = igmp_create_message ();

	if (sptr_igmp_message == NULL)
		{
		IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Failed to create an IGMP message when deserializing received packet.\n");

		return (NULL);
		}
		
	/* fill in the IGMP message */
	sptr_igmp_message->type =  (enum IGMP_MESSAGE_TYPE) sptr_igmp_payload->message_type;

	sptr_igmp_message->max_response_time = sptr_igmp_payload->max_response_time;

	sptr_igmp_message->group_ip_address = deserialize_long (sptr_igmp_payload->group_ip_address);

	sptr_igmp_message->source_ip_address = sptr_ip_parameters->source_address;

	sptr_igmp_message->receiving_port = sptr_ip_parameters->rx_port_number;

	return (sptr_igmp_message);
}
/********************************************************************************************/
static enum BOOLEAN igmp_received_valid_ip_packet (IP_PARAMETERS *sptr_ip_parameters)
{
	if (igmp.port_table[sptr_ip_parameters->rx_port_number].enabled == FALSE)
		{
		IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Received packet on disabled port %u.\n",sptr_ip_parameters->rx_port_number);

		return (FALSE);
		}

	if (!IN_CLASS_D (sptr_ip_parameters->destination_address))
		{
		IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Received packet not a multicast packet.\n");

		return (FALSE);
		}
	
	return (TRUE);		
}
/********************************************************************************************/
static enum BOOLEAN igmp_received_valid_message (IGMP_PAYLOAD *sptr_igmp_payload, UINT size_of_igmp_payload)
{
	if (size_of_igmp_payload < IGMP_MINIMUM_MESSAGE_SIZE)
		{
		IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Received IGMP message with lesser than expected length.\n");

		return (FALSE);
		}
	
	if (calculate_ip_checksum (NULL, (BYTE *) sptr_igmp_payload, (USHORT) size_of_igmp_payload) != 0x0000)
		{
		IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Received IGMP message failed checksum validation\n");

		return (FALSE);
		}

	if (sptr_igmp_payload->group_ip_address != 0x00000000L)
		{
		if (!IN_CLASS_D (host_to_net_long (sptr_igmp_payload->group_ip_address)))
			{
			IGMP_PROTOCOL_ALARM_TRACE (IGMP_ALARM_TRACE, "IGMP: Received IGMP message Group not a Class D address!\n");

			return (FALSE);
			}
		}

	return (TRUE);
}