ospf_external_route_calculation.c

vxworks下ospf协议栈

        sptr_routing_table_entry_for_N->path_type = OSPF_ROUTE_PATH_TYPE_1_EXTERNAL;
        sptr_routing_table_entry_for_N->path_cost = distance_X + cost_Y;
        sptr_routing_table_entry_for_N->type2_cost = 0x00;
        }

    return;
}

/*************************************************************************
*
* ospf_install_new_external_path_based_on_cost - install new external path based on cost
*
* This routine will install a new external path based on cost of
* external link state advertisements.
*
* <destination_N> External advertisement destination
*
* <sptr_routing_table_entry_for_N> Routing table entry for destination
*
* <distance_X> Distance of path
*
* <cost_Y> Cost of link
*
* <advertisement> Advertisement to be installed
*
* <sptr_routing_table_entry_for_forwarding_address> Routing table entry for forwarding address
*
* <sptr_routing_table_entry_for_ASBR> Routing table entry for ASBR
*
* RETURNS: TRUE or FALSE
*
* ERRNO: N/A
*
* NOMANUAL
*/
/**************************************************************************************//* section 16.4, item (6) OSPF Specification + section 3.5, item (5) RFC-1587 NSSA Option */
static enum BOOLEAN ospf_install_new_external_path_based_on_cost (ULONG destination_N,
    OSPF_ROUTING_TABLE_NODE *sptr_routing_table_node_for_N, ULONG distance_X,ULONG cost_Y,
    UNION_OSPF_LINK_STATE_ADVERTISEMENT *advertisement, OSPF_ROUTING_TABLE_ENTRY *sptr_routing_table_entry_for_forwarding_address,
    OSPF_ROUTING_TABLE_ENTRY *sptr_routing_table_entry_for_ASBR)
{
    ULONG tos0_metric =0;
    enum OSPF_ROUTING_TABLE_UPDATE_ACTION action;
    OSPF_ROUTING_TABLE_ENTRY  *sptr_routing_table_entry_for_N =NULL;
    enum BOOLEAN return_value;

    OSPF_PRINTF_PROLOGUE (OSPF_PROLOGUE_PRINTF, "OSPF: Entering ospf_install_new_external_path_based_on_cost\r\n");

#if !defined (__NSSA__)
    tos0_metric = net_to_host_long (advertisement->sptr_external->tos0_metric);
#else
    tos0_metric = net_to_host_long (advertisement->sptr_type_7->tos0_metric);
#endif /*__NSSA__*/

    sptr_routing_table_entry_for_N = sptr_routing_table_node_for_N->sptr_routing_table_entry;

    action = ospf_compare_costs_of_external_paths (sptr_routing_table_entry_for_N, distance_X, cost_Y, tos0_metric);

    switch (action)
        {
        case OSPF_REPLACE_PATH:
            {
            return_value = TRUE;

            OSPF_PRINTF_ROUTING_TABLE (OSPF_ROUTING_TABLE_PRINTF, "OSPF: Replacing External Path\r\n");

            ospf_install_the_external_area_path_to_N_and_replace_rtm_route (destination_N, sptr_routing_table_node_for_N, advertisement,
                sptr_routing_table_entry_for_forwarding_address, sptr_routing_table_entry_for_ASBR, distance_X, cost_Y); /* delete followed by an add */

            break;
            }

        case OSPF_ADD_PATH:
            {
            OSPF_PRINTF_ROUTING_TABLE (OSPF_ROUTING_TABLE_PRINTF, "OSPF: Adding External Path\r\n");

#if !defined (__NSSA__)
            if ((advertisement->sptr_external->tos0_forwarding_address != 0x00000000L) &&
                (sptr_routing_table_entry_for_forwarding_address != NULL))
#else
            if ((advertisement->sptr_type_7->tos0_forwarding_address != 0x00000000L) &&
                (sptr_routing_table_entry_for_forwarding_address != NULL))
#endif /*__NSSA__*/
                {
                return_value = ospf_add_new_path_to_routing_table_entry_and_update_rtm (sptr_routing_table_node_for_N,
                    sptr_routing_table_entry_for_forwarding_address->destination_id, sptr_routing_table_entry_for_forwarding_address);
                }
            else
                {
                return_value = ospf_add_new_path_to_routing_table_entry_and_update_rtm (sptr_routing_table_node_for_N,
                    sptr_routing_table_entry_for_ASBR->destination_id, sptr_routing_table_entry_for_ASBR);
                }

            break;
            }

        case OSPF_NO_ACTION:
            {

            return_value = FALSE;

            break;
            }

        default:
            {
            return_value = FALSE;

            break;
            }
        }

    return (return_value);
}

/*************************************************************************
*
* ospf_compare_costs_of_external_paths - compares the costs of external paths
*
* This routine will compare the costs of external paths
*
* <sptr_routing_table_entry_for_N> Routing table entry for destination
*
* <distance_X> Distance of path
*
* <cost_Y> Cost of link
*
* <tos0_metric> Metric of external link
*
* RETURNS: OSPF_NO_ACTION or OSPF_ADD_PATH or OSPF_DELETE_PATH or OSPF_REPLACE_PATH
*
* ERRNO: N/A
*
* NOMANUAL
*/
static enum OSPF_ROUTING_TABLE_UPDATE_ACTION ospf_compare_costs_of_external_paths (OSPF_ROUTING_TABLE_ENTRY *sptr_routing_table_entry_for_N,
    ULONG distance_X,ULONG cost_Y,ULONG tos0_metric)
{
    enum OSPF_ROUTING_TABLE_UPDATE_ACTION action;

    OSPF_PRINTF_PROLOGUE (OSPF_PROLOGUE_PRINTF, "OSPF: Entering ospf_compare_costs_of_external_paths\r\n");

    action = OSPF_NO_ACTION;

    if ((tos0_metric & OSPF_ASE_bit_E) != OSPF_ASE_bit_E)
        {
        if (sptr_routing_table_entry_for_N->path_type == OSPF_ROUTE_PATH_TYPE_1_EXTERNAL)
            {
            if (sptr_routing_table_entry_for_N->path_cost > distance_X + cost_Y)
                {
                action = OSPF_REPLACE_PATH;
                }
            else if (sptr_routing_table_entry_for_N->path_cost == distance_X + cost_Y)
                {
#if defined (__NSSA__)                                                                  /* Any type 5 LSA*/
                if ( sptr_routing_table_entry_for_N->link_type == OSPF_LS_AS_EXTERNAL)
                    {
                    action = OSPF_REPLACE_PATH;
                    }
                else if ((sptr_routing_table_entry_for_N->link_type == OSPF_LS_TYPE_7) && (sptr_routing_table_entry_for_N->optional_capabilities._bit.dont_propagate == FALSE) &&
                            (sptr_routing_table_entry_for_N->sptr_link_state_origin->sptr_type_7->tos0_forwarding_address != 0x00000000L))
                    {
                    action = OSPF_REPLACE_PATH;
                    }
#else
                action = OSPF_ADD_PATH;
#endif /*__NSSA__*/
                }
            }
        else
            {
            action = OSPF_REPLACE_PATH;
            }
        }
    else if (sptr_routing_table_entry_for_N->path_type == OSPF_ROUTE_PATH_TYPE_2_EXTERNAL)
        {
        if (sptr_routing_table_entry_for_N->type2_cost > cost_Y)
            {
            action = OSPF_REPLACE_PATH;
            }
        else if (sptr_routing_table_entry_for_N->type2_cost == cost_Y)
            {
            if (sptr_routing_table_entry_for_N->path_cost > distance_X)
                {
                action = OSPF_REPLACE_PATH;
                }
            else if (sptr_routing_table_entry_for_N->path_cost == distance_X)
                {
                action = OSPF_ADD_PATH;
                }
            }
        }

    return (action);
}

/*************************************************************************
*
* ospf_invalidate_type_7_route_entry - invalidate type 7 routing table entry
*
* This routine will invalidate a type 7 routing table entry.
*
* <sptr_type_7> Type 7 link state advertisement
*
* RETURNS: N/A
*
* ERRNO: N/A
*
* NOMANUAL
*/
#if defined (__NSSA__)
void ospf_invalidate_type_7_route_entry (OSPF_TYPE_7_LINK_ADVERTISEMENT_HEADER *sptr_type_7)
{
    ULONG destination_N =0;
    ULONG   tos0_metric =0;
    OSPF_ROUTING_TABLE_NODE *sptr_routing_table_node =NULL;
    ULONG advertising_router_from_rxed_advertisement =0;

    OSPF_PRINTF_PROLOGUE (OSPF_PROLOGUE_PRINTF, "OSPF: Entering ospf_invalidate_type_7_route_entry\r\n");

    destination_N = net_to_host_long (sptr_type_7->ls_header.id);

    tos0_metric = net_to_host_long (sptr_type_7->tos0_metric);

    advertising_router_from_rxed_advertisement = net_to_host_long (sptr_type_7->ls_header.advertising_router);

    if ( (tos0_metric & OSPF_ASE_bit_E) == OSPF_ASE_bit_E)
        {
        sptr_routing_table_node = ospf_find_routing_table_node  (destination_N, (enum OSPF_LS_TYPE) sptr_type_7->ls_header.type,
            OSPF_ROUTE_PATH_TYPE_2_EXTERNAL, NULL);  /* NEWRT LOOKUP */
        }
    else
        {
        sptr_routing_table_node = ospf_find_routing_table_node (destination_N, (enum OSPF_LS_TYPE) sptr_type_7->ls_header.type,
            OSPF_ROUTE_PATH_TYPE_1_EXTERNAL, NULL); /* NEWRT LOOKUP */
        }

    if ( (sptr_routing_table_node != NULL) &&
        (advertising_router_from_rxed_advertisement == sptr_routing_table_node->sptr_routing_table_entry->advertising_router) )
        {
        ospf_invalidate_routing_table_entry (sptr_routing_table_node, sptr_type_7->network_mask, destination_N, NULL);

        /* code removed on 8/2/1998 - No longer needed - this is done in the above function ospf_invalidate_routing_table_entry */
        /*#$-NOTE:note40-$#*/

        }
}
#endif /*__NSSA__*/

/*************************************************************************
*
* ospf_install_the_external_area_path_to_N_and_replace_rtm_route - install external path and update rtm
*
* This routine will install the external area path and replace the rtm route.
*
* <destination_N> External advertisement destination
*
* <sptr_routing_table_node_for_N> Routing table node for destination
*
* <advertisement> Advertisement to be installed
*
* <sptr_routing_table_entry_for_forwarding_address> Routing table entry for forwarding address
*
* <sptr_routing_table_entry_for_ASBR> Routing table entry for ASBR
*
* <distance_X> Distance of path
*
* <cost_Y> Cost of link
*
* RETURNS: N/A
*
* ERRNO: N/A
*
* NOMANUAL
*/
static void ospf_install_the_external_area_path_to_N_and_replace_rtm_route (ULONG destination_N,
    OSPF_ROUTING_TABLE_NODE *sptr_routing_table_node_for_N, UNION_OSPF_LINK_STATE_ADVERTISEMENT *advertisement,
    OSPF_ROUTING_TABLE_ENTRY *sptr_routing_table_entry_for_forwarding_address,
    OSPF_ROUTING_TABLE_ENTRY *sptr_routing_table_entry_for_ASBR, ULONG distance_X,ULONG cost_Y)
{
    OSPF_ROUTING_TABLE_ENTRY  *sptr_routing_table_entry_for_N =NULL;

    OSPF_PRINTF_PROLOGUE (OSPF_PROLOGUE_PRINTF, "OSPF: Entering ospf_install_the_external_area_path_to_N_and_replace_rtm_route\r\n");

    sptr_routing_table_entry_for_N = sptr_routing_table_node_for_N->sptr_routing_table_entry;

#if defined (__RTM__)
    ospf_export_route_to_other_protocols (OSPF_DELETE_PATH, sptr_routing_table_entry_for_N); /* Replace- so delete first */
#endif

    ospf_install_the_external_area_path_to_N (destination_N, sptr_routing_table_entry_for_N, advertisement,
        sptr_routing_table_entry_for_forwarding_address, sptr_routing_table_entry_for_ASBR, distance_X, cost_Y);


#if defined (__RTM__)
    ospf_export_route_to_other_protocols (OSPF_ADD_PATH, sptr_routing_table_entry_for_N);
#endif
}

/* SPR 85050 -- Begin */
/*************************************************************************
*
* ospf_compare_costs_of_external_lsdb_entries
*
* This routine is called to compare the costs of two external lsdb entries
* it similar to ospf_compare_costs_of_external_paths however the comparison
* is between two tos0_metric values.
*
*
* RETURNS: TRUE if new_metric is better than metric, FALSE otherwise
*
* ERRNO: N/A
*
* NOMANUAL
*/

enum BOOLEAN ospf_compare_costs_of_external_lsdb_entries (ULONG new_metric, ULONG metric)
{

    OSPF_PRINTF_PROLOGUE (OSPF_PROLOGUE_PRINTF, "OSPF: Entering ospf_compare_costs_of_external_lsdb_entries\r\n");


    if ((new_metric & OSPF_ASE_bit_E) == OSPF_ASE_bit_E)
    {
		/* new_metric is type 2 */

        if ((metric & OSPF_ASE_bit_E) == OSPF_ASE_bit_E)
        {
			if((new_metric & 0x00ffffff) < (metric & 0x00ffffff))
			{
				return(TRUE);
			}
		}

		/* metric is either better or type 1 */
		return(FALSE);
	}
	else
	{
		/* new_metric is type 1 */

		if((metric & OSPF_ASE_bit_E) != OSPF_ASE_bit_E)
		{
			if((new_metric & 0x00ffffff) >= (metric & 0x00ffffff))
			{
				return(FALSE);
			}
		}

		/* metric is either worse or type 2 */
		return(TRUE);
	}
}
/* SPR 85050 -- End */
/**************************************************************************************/