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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 */
/** */
/** Address Resolution Protocol (ARP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_arp.h"
#include "nx_packet.h"
#ifndef NX_DISABLE_IPV4
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_arp_periodic_update PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function processes ARP periodic update requests by walking */
/* through the dynamic ARP list to see if another ARP request needs to */
/* be sent. */
/* */
/* INPUT */
/* */
/* ip_ptr Pointer to IP instance */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _nx_arp_packet_send Send periodic ARP request out */
/* _nx_packet_transmit_release Release queued packet */
/* */
/* CALLED BY */
/* */
/* _nx_ip_thread_entry IP helper thread */
/* */
/* 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 */
/* */
/**************************************************************************/
VOID _nx_arp_periodic_update(NX_IP *ip_ptr)
{
TX_INTERRUPT_SAVE_AREA
ULONG i;
NX_ARP *arp_entry;
NX_PACKET *packet_ptr;
NX_PACKET *next_packet_ptr;
/* Pickup pointer to ARP dynamic list. */
arp_entry = ip_ptr -> nx_ip_arp_dynamic_list;
/* Loop through the active ARP entries to see if they need updating. */
for (i = 0; i < ip_ptr -> nx_ip_arp_dynamic_active_count; i++)
{
/* Check this ARP entry to see if it need updating. */
if (arp_entry -> nx_arp_entry_next_update)
{
/* Decrement the next update field. */
arp_entry -> nx_arp_entry_next_update--;
/* Determine if an ARP expiration is present. */
if (!arp_entry -> nx_arp_entry_next_update)
{
/* Yes, an ARP expiration is present. */
/* Determine if the retry counter has been exceeded. */
if (arp_entry -> nx_arp_retries == NX_ARP_MAXIMUM_RETRIES)
{
/* The number of retries has been exceeded. The entry is removed
from the active list and any queued packet is released. */
/* Disable interrupts. */
TX_DISABLE
/* This ARP entry has expired, remove it from the active ARP list. Check to make
sure it is still active. */
if (arp_entry -> nx_arp_active_list_head)
{
/* Determine if this is the only ARP entry on the list. */
if (arp_entry == arp_entry -> nx_arp_active_next)
{
/* Remove the entry from the list. */
*(arp_entry -> nx_arp_active_list_head) = NX_NULL;
}
else
{
/* Remove the entry from a list of more than one entry. */
/* Update the list head pointer. */
if (*(arp_entry -> nx_arp_active_list_head) == arp_entry)
{
*(arp_entry -> nx_arp_active_list_head) = arp_entry -> nx_arp_active_next;
}
/* Update the links of the adjacent ARP entries. */
(arp_entry -> nx_arp_active_next) -> nx_arp_active_previous =
arp_entry -> nx_arp_active_previous;
(arp_entry -> nx_arp_active_previous) -> nx_arp_active_next =
arp_entry -> nx_arp_active_next;
}
/* Decrease the number of active ARP entries. */
ip_ptr -> nx_ip_arp_dynamic_active_count--;
/* Clear the active head pointer. */
arp_entry -> nx_arp_active_list_head = NX_NULL;
}
/* Determine if this is the only ARP entry on the dynamic list. */
if (arp_entry != arp_entry -> nx_arp_pool_next)
{
/* No. Place the ARP entry at the end of the dynamic ARP pool, which is where new
ARP requests are allocated from. */
/* Remove the entry from a list of more than one entry. */
/* Update the links of the adjacent ARP dynamic pool entries. */
(arp_entry -> nx_arp_pool_next) -> nx_arp_pool_previous =
arp_entry -> nx_arp_pool_previous;
(arp_entry -> nx_arp_pool_previous) -> nx_arp_pool_next =
arp_entry -> nx_arp_pool_next;
/* Update the list head pointer. */
if (ip_ptr -> nx_ip_arp_dynamic_list == arp_entry)
{
ip_ptr -> nx_ip_arp_dynamic_list = arp_entry -> nx_arp_pool_next;
}
/* Add ARP entry to the end of the list. */
arp_entry -> nx_arp_pool_next =
ip_ptr -> nx_ip_arp_dynamic_list;
arp_entry -> nx_arp_pool_previous =
(ip_ptr -> nx_ip_arp_dynamic_list) -> nx_arp_pool_previous;
((ip_ptr -> nx_ip_arp_dynamic_list) -> nx_arp_pool_previous) -> nx_arp_pool_next =
arp_entry;
(ip_ptr -> nx_ip_arp_dynamic_list) -> nx_arp_pool_previous = arp_entry;
}
/* Pickup the queued packets head pointer. */
next_packet_ptr = arp_entry -> nx_arp_packets_waiting;
/* Clear the queued packets head pointer. */
arp_entry -> nx_arp_packets_waiting = NX_NULL;
/* Restore interrupts. */
TX_RESTORE
/* Loop to remove all queued packets. */
while (next_packet_ptr)
{
/* Pickup the packet pointer at the head of the queue. */
packet_ptr = next_packet_ptr;
/* Move to the next packet in the queue. */
next_packet_ptr = next_packet_ptr -> nx_packet_queue_next;
/* Clear the next packet queue pointer. */
packet_ptr -> nx_packet_queue_next = NX_NULL;
#ifndef NX_DISABLE_IP_INFO
/* Increment the IP send packets dropped count. */
ip_ptr -> nx_ip_send_packets_dropped++;
#endif
/* Release the packet that was queued for the expired ARP entry. */
_nx_packet_transmit_release(packet_ptr);
}
}
else
{
/* We haven't yet had a response to this ARP request so send it again! */
/* Increment the ARP retry counter. */
arp_entry -> nx_arp_retries++;
/* Setup the ARP update rate to the maximum value again. */
arp_entry -> nx_arp_entry_next_update = NX_ARP_UPDATE_RATE;
/* Send the ARP request out. */
_nx_arp_packet_send(ip_ptr, arp_entry -> nx_arp_ip_address, arp_entry -> nx_arp_ip_interface);
}
}
}
/* Move to the next ARP entry. */
arp_entry = arp_entry -> nx_arp_pool_next;
}
/* Reduce the defend timeout of interfaces. */
for (i = 0; i < NX_MAX_PHYSICAL_INTERFACES; i++)
{
if (ip_ptr -> nx_ip_interface[i].nx_interface_valid == NX_FALSE)
{
continue;
}
if (ip_ptr -> nx_ip_interface[i].nx_interface_arp_defend_timeout == 0)
{
continue;
}
ip_ptr -> nx_ip_interface[i].nx_interface_arp_defend_timeout--;
}
}
#endif /* !NX_DISABLE_IPV4 */
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