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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Component */
/** */
/** Internet Protocol version 6 Default Router Table (IPv6 router) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_ipv6.h"
#include "nx_nd_cache.h"
#include "nx_icmpv6.h"
#ifdef FEATURE_NX_IPV6
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nxd_ipv6_router_lookup PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function finds a valid router from the default router table, */
/* and this function also return the pointer to the router's cache */
/* entry in the NetX Duo cache table. */
/* */
/* INPUT */
/* */
/* ip_ptr IP instance pointer */
/* if_ptr Pointer to interface */
/* router_address Pointer to default router */
/* nd_cache_entry Pointer to associated ND entry*/
/* */
/* OUTPUT */
/* */
/* status Non zero status */
/* router not found */
/* Zero status, router found */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _nx_icmpv6_process_redirect */
/* _nx_ipv6_packet_send */
/* */
/* NOTE */
/* */
/* Internal Function. Caller must have acquired IP protection mutex. */
/* This function should not be called from ISR. Although it has no */
/* blocking calls it will slow down response time. */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Yuxin Zhou Initial Version 6.0 */
/* 09-30-2020 Yuxin Zhou Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _nxd_ipv6_router_lookup(NX_IP *ip_ptr, NX_INTERFACE *if_ptr, ULONG *router_address, void **nd_cache_entry)
{
UINT i;
UINT table_size;
UINT routers_checked;
NX_IPV6_DEFAULT_ROUTER_ENTRY *rt_entry;
ND_CACHE_ENTRY *NDCacheEntry;
NX_ASSERT(nd_cache_entry != NX_NULL)
/* Initialize cache pointer to NULL (if no router found). */
*nd_cache_entry = NULL;
/* Set a local variable for convenience. */
table_size = ip_ptr -> nx_ipv6_default_router_table_size;
/* Check if there have been any routers added to the table. */
if (table_size == 0)
{
/* Return a non zero (e.g. unsuccessful) error status. */
return(NX_NOT_SUCCESSFUL);
}
/* Loop to check the router table. */
for (i = 0; table_size && (i < NX_IPV6_DEFAULT_ROUTER_TABLE_SIZE); i++)
{
/* Local pointer for convenience. */
rt_entry = &(ip_ptr -> nx_ipv6_default_router_table[i]);
/* Does this slot contain a valid router? */
if ((rt_entry -> nx_ipv6_default_router_entry_flag & NX_IPV6_ROUTE_TYPE_VALID) &&
(rt_entry -> nx_ipv6_default_router_entry_interface_ptr == if_ptr))
{
/* Keep track of valid entries we have checked. */
NDCacheEntry = rt_entry -> nx_ipv6_default_router_entry_neighbor_cache_ptr;
/* Is this router reachable? */
if (!NDCacheEntry ||
(NDCacheEntry -> nx_nd_cache_nd_status < ND_CACHE_STATE_REACHABLE) ||
(NDCacheEntry -> nx_nd_cache_nd_status > ND_CACHE_STATE_PROBE))
{
/* No, skip over. */
table_size--;
continue;
}
/* Yes, copy this router address into the return pointer. */
COPY_IPV6_ADDRESS(ip_ptr -> nx_ipv6_default_router_table[i].nx_ipv6_default_router_entry_router_address, router_address);
/* Copy the router's cache entry pointer to the supplied cache table pointer. */
*nd_cache_entry = ip_ptr -> nx_ipv6_default_router_table[i].nx_ipv6_default_router_entry_neighbor_cache_ptr;
/* We're done. Break out of the search. */
return(NX_SUCCESS);
}
}
/* If we are here, we did not find a suitable default router. Do a search
of routers previously reachable. */
/* Start at the round robin index so we don't always choose the first
less-than-reachable router in the table. */
i = ip_ptr -> nx_ipv6_default_router_table_round_robin_index;
/* Find a router with previously known reachability. */
for (routers_checked = 0; routers_checked < NX_IPV6_DEFAULT_ROUTER_TABLE_SIZE; routers_checked++)
{
/* Local pointer for convenience. */
rt_entry = &(ip_ptr -> nx_ipv6_default_router_table[i]);
/* Does this slot contain a valid router? */
if ((rt_entry -> nx_ipv6_default_router_entry_flag & NX_IPV6_ROUTE_TYPE_VALID) &&
(rt_entry -> nx_ipv6_default_router_entry_interface_ptr == if_ptr))
{
/* Yes, copy this router to the return pointer. */
COPY_IPV6_ADDRESS(rt_entry -> nx_ipv6_default_router_entry_router_address, router_address);
/* Copy the router's cache entry pointer to the supplied cache table pointer. */
*nd_cache_entry = rt_entry -> nx_ipv6_default_router_entry_neighbor_cache_ptr;
/* Update the index so the same router is not chosen again if there
any other less-than-reachable routers we can choose, RFC 2461 6.3.6. */
ip_ptr -> nx_ipv6_default_router_table_round_robin_index++;
/* Do we need wrap the index? */
if (ip_ptr -> nx_ipv6_default_router_table_round_robin_index == NX_IPV6_DEFAULT_ROUTER_TABLE_SIZE)
{
/* Yes, start back at the first slot. */
ip_ptr -> nx_ipv6_default_router_table_round_robin_index = 0;
}
/* We're done. Return successful outcome status. */
return(NX_SUCCESS);
}
/* Are we past the end of the table? */
if (i == NX_IPV6_DEFAULT_ROUTER_TABLE_SIZE - 1)
{
/* Yes, wrap to the first slot.*/
i = 0;
}
else
{
i++;
}
}
/* Router not found. */
return(NX_NOT_SUCCESSFUL);
}
#endif /* FEATURE_NX_IPV6 */
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