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nuttx/net/netdev/netdev_findbyaddr.c
Zhe Weng 3b74cfecc2 net/route: Support longest prefix match for routing 
Support longest prefix match routing described as "Longest Match" in
RFC 1812, Section 5.2.4.3, Page 75.

Introduced `prefixlen` to indicate the prefix length of currently
founded route, and only looks up for longer prefix in all later steps.

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
2024-01-09 05:58:10 -08:00

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/****************************************************************************
* net/netdev/netdev_findbyaddr.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <netinet/in.h>
#include <nuttx/net/netdev.h>
#include <nuttx/net/ip.h>
#include "arp/arp.h"
#include "neighbor/neighbor.h"
#include "utils/utils.h"
#include "devif/devif.h"
#include "inet/inet.h"
#include "route/route.h"
#include "netdev/netdev.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: netdev_prefixlen_findby_lipv4addr
*
* Description:
* Find a previously registered network device by matching a local address
* with the subnet served by the device. Only "up" devices are considered
* (since a "down" device has no meaningful address).
*
* Input Parameters:
* lipaddr - Local, IPv4 address assigned to the network device. Or any
* IPv4 address on the sub-net served by the network device.
* prefixlen - The length of matching prefix. Range: -1(no match) ~ 32
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv4
static FAR struct net_driver_s *
netdev_prefixlen_findby_lipv4addr(in_addr_t lipaddr, FAR int8_t *prefixlen)
{
FAR struct net_driver_s *dev;
FAR struct net_driver_s *bestdev = NULL;
int8_t bestpref = -1;
#ifdef CONFIG_ROUTE_LONGEST_MATCH
int8_t len;
#endif
/* Examine each registered network device */
net_lock();
for (dev = g_netdevices; dev; dev = dev->flink)
{
/* Is the interface in the "up" state? */
if ((dev->d_flags & IFF_UP) != 0 &&
!net_ipv4addr_cmp(dev->d_ipaddr, INADDR_ANY))
{
#ifndef CONFIG_ROUTE_LONGEST_MATCH
/* Yes.. check for an address match (under the netmask) */
if (net_ipv4addr_maskcmp(dev->d_ipaddr, lipaddr,
dev->d_netmask))
{
/* Its a match */
bestdev = dev;
bestpref = 32; /* Regard as best (exact) match */
break;
}
#else
/* Longest prefix flow: First, check for an exact address match */
if (net_ipv4addr_cmp(dev->d_ipaddr, lipaddr))
{
/* It's an exact match */
bestdev = dev;
bestpref = 32;
break;
}
/* Then, check for an address match (under the netmask) */
if (net_ipv4addr_maskcmp(dev->d_ipaddr, lipaddr,
dev->d_netmask))
{
len = (int8_t)net_ipv4_mask2pref(dev->d_netmask);
/* Regard current device as better if:
* 1. It has longer prefix length
* 2. It has the same prefix length but it has target address
* in the ARP cache (We don't have other information
* for the precedence of networks)
*/
if (len > bestpref
#ifdef CONFIG_NET_ARP
|| (len == bestpref && arp_find(lipaddr, NULL, dev) == OK)
#endif
)
{
bestdev = dev;
bestpref = len;
}
}
#endif /* CONFIG_ROUTE_LONGEST_MATCH */
}
}
net_unlock();
*prefixlen = bestpref;
return bestdev;
}
#endif /* CONFIG_NET_IPv4 */
/****************************************************************************
* Name: netdev_prefixlen_findby_lipv6addr
*
* Description:
* Find a previously registered network device by matching a local address
* with the subnet served by the device. Only "up" devices are considered
* (since a "down" device has no meaningful address).
*
* Input Parameters:
* lipaddr - Local, IPv6 address assigned to the network device. Or any
* IPv6 address on the sub-net served by the network device.
* prefixlen - The length of matching prefix. Range: -1(no match) ~ 128
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
static FAR struct net_driver_s *
netdev_prefixlen_findby_lipv6addr(const net_ipv6addr_t lipaddr,
FAR int16_t *prefixlen)
{
FAR struct net_driver_s *dev;
FAR struct net_driver_s *bestdev = NULL;
int16_t bestpref = -1;
#ifdef CONFIG_ROUTE_LONGEST_MATCH
FAR struct netdev_ifaddr6_s *ifaddr6;
FAR struct neighbor_entry_s *ne;
FAR struct net_driver_s *hint;
int16_t len;
#endif
net_lock();
#ifdef CONFIG_ROUTE_LONGEST_MATCH
/* Find a hint from neighbor table in case same prefix length exists on
* multiple devices.
*/
ne = neighbor_findentry(lipaddr);
hint = ne ? ne->ne_dev : NULL;
#endif
/* Examine each registered network device */
for (dev = g_netdevices; dev; dev = dev->flink)
{
/* Is the interface in the "up" state? */
if ((dev->d_flags & IFF_UP) != 0 && NETDEV_HAS_V6ADDR(dev))
{
#ifndef CONFIG_ROUTE_LONGEST_MATCH
/* Yes.. check for an address match (under the netmask) */
if (NETDEV_V6ADDR_ONLINK(dev, lipaddr))
{
/* Its a match */
bestdev = dev;
bestpref = 128; /* Regard as best (exact) match */
break;
}
#else
/* Longest prefix flow: First, check for an exact address match */
if (NETDEV_IS_MY_V6ADDR(dev, lipaddr))
{
/* It's an exact match */
bestdev = dev;
bestpref = 128;
break;
}
/* Then, check for an address match (under the netmask) */
if ((ifaddr6 = netdev_ipv6_lookup(dev, lipaddr, true)) != NULL)
{
len = (int16_t)net_ipv6_mask2pref(ifaddr6->mask);
/* Regard current device as better if:
* 1. It has longer prefix length
* 2. It has the same prefix length but it has target address
* in the neighbor cache (We don't have other information
* for the precedence of networks)
*/
if (len > bestpref || (len == bestpref && hint == dev))
{
bestdev = dev;
bestpref = len;
}
}
#endif /* CONFIG_ROUTE_LONGEST_MATCH */
}
}
net_unlock();
*prefixlen = bestpref;
return bestdev;
}
#endif /* CONFIG_NET_IPv6 */
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: netdev_findby_lipv4addr
*
* Description:
* Find a previously registered network device by matching a local address
* with the subnet served by the device. Only "up" devices are considered
* (since a "down" device has no meaningful address).
*
* Input Parameters:
* lipaddr - Local, IPv4 address assigned to the network device. Or any
* IPv4 address on the sub-net served by the network device.
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv4
FAR struct net_driver_s *netdev_findby_lipv4addr(in_addr_t lipaddr)
{
int8_t prefixlen;
return netdev_prefixlen_findby_lipv4addr(lipaddr, &prefixlen);
}
#endif /* CONFIG_NET_IPv4 */
/****************************************************************************
* Name: netdev_findby_lipv6addr
*
* Description:
* Find a previously registered network device by matching a local address
* with the subnet served by the device. Only "up" devices are considered
* (since a "down" device has no meaningful address).
*
* Input Parameters:
* lipaddr - Local, IPv6 address assigned to the network device. Or any
* IPv6 address on the sub-net served by the network device.
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
FAR struct net_driver_s *netdev_findby_lipv6addr(
const net_ipv6addr_t lipaddr)
{
int16_t prefixlen;
return netdev_prefixlen_findby_lipv6addr(lipaddr, &prefixlen);
}
#endif /* CONFIG_NET_IPv6 */
/****************************************************************************
* Name: netdev_findby_ripv4addr
*
* Description:
* Find a previously registered network device by matching the remote
* IPv4 address that can be reached by the device.
*
* Input Parameters:
* lipaddr - Local, bound address of a connection (used only if ripaddr is
* the broadcast address).
* ripaddr - Remote address of a connection to use in the lookup
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv4
FAR struct net_driver_s *netdev_findby_ripv4addr(in_addr_t lipaddr,
in_addr_t ripaddr)
{
FAR struct net_driver_s *dev;
int8_t prefixlen;
#ifdef CONFIG_NET_ROUTE
in_addr_t router;
int ret;
#endif
/* First, check if this is the broadcast IP address */
if (net_ipv4addr_cmp(ripaddr, INADDR_BROADCAST))
{
/* Yes.. Check the local, bound address. Is it INADDR_ANY? */
if (net_ipv4addr_cmp(lipaddr, INADDR_ANY))
{
/* Yes.. In this case, I think we are supposed to send the
* broadcast packet out ALL locally available networks. I am not
* sure of that and, in any event, there is nothing we can do
* about that here.
*/
return netdev_default();
}
else
{
/* Return the device associated with the local address */
return netdev_findby_lipv4addr(lipaddr);
}
}
/* Check if the address maps to a locally available network
* Note: If longest prefix match is not enabled, prefixlen will be 32 if
* matched and it will disable further routing lookup.
*/
dev = netdev_prefixlen_findby_lipv4addr(ripaddr, &prefixlen);
#ifdef CONFIG_NET_ROUTE
/* If we have a routing table, then perhaps we can find the local
* address of a router that can forward packets to the external network
* with longer prefix.
*/
ret = net_ipv4_router(ripaddr, &router, prefixlen);
if (ret >= 0)
{
/* Success... try to find the network device associated with the local
* router address
*/
dev = netdev_findby_lipv4addr(router);
}
#endif /* CONFIG_NET_ROUTE */
/* Return the device we found. */
if (dev)
{
return dev;
}
/* The above lookup will fail if the packet is being sent out of our
* out subnet to a router and there is no routing information. Let's
* try the default network device.
*/
return netdev_default();
}
#endif /* CONFIG_NET_IPv4 */
/****************************************************************************
* Name: netdev_findby_ripv6addr
*
* Description:
* Find a previously registered network device by matching the remote
* IPv6 address that can be reached by the device.
*
* Input Parameters:
* lipaddr - Local, bound address of a connection (used only if ripaddr is
* a multicast address).
* ripaddr - Remote address of a connection to use in the lookup
*
* Returned Value:
* Pointer to driver on success; null on failure
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
FAR struct net_driver_s *netdev_findby_ripv6addr(
const net_ipv6addr_t lipaddr,
const net_ipv6addr_t ripaddr)
{
FAR struct net_driver_s *dev;
int16_t prefixlen;
#ifdef CONFIG_NET_ROUTE
net_ipv6addr_t router;
int ret;
#endif
/* First, check if this is the multicast IP address */
if (net_is_addr_mcast(ripaddr))
{
/* Yes.. Check the local, bound address. Is it the IPv6 unspecified
* address?
*/
if (net_ipv6addr_cmp(lipaddr, g_ipv6_unspecaddr))
{
/* Yes.. In this case, I think we are supposed to send the
* broadcast packet out ALL locally available networks. I am not
* sure of that and, in any event, there is nothing we can do
* about that here.
*/
return netdev_default();
}
else
{
/* Return the device associated with the local address */
return netdev_findby_lipv6addr(lipaddr);
}
}
/* Check if the address maps to a locally available network
* Note: If longest prefix match is not enabled, prefixlen will be 128 if
* matched and it will disable further routing lookup.
*/
dev = netdev_prefixlen_findby_lipv6addr(ripaddr, &prefixlen);
#ifdef CONFIG_NET_ROUTE
/* If we have a routing table, then perhaps we can find the local
* address of a router that can forward packets to the external network
* with longer prefix.
*/
ret = net_ipv6_router(ripaddr, router, prefixlen);
if (ret >= 0)
{
/* Success... try to find the network device associated with the local
* router address
*/
dev = netdev_findby_lipv6addr(router);
}
#endif /* CONFIG_NET_ROUTE */
/* Return the device we found. */
if (dev)
{
return dev;
}
/* The above lookup will fail if the packet is being sent out of our
* out subnet to a router and there is no routing information. Let's
* try the default network device.
*/
return netdev_default();
}
#endif /* CONFIG_NET_IPv6 */
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