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incubator-nuttx/net/nat/ipv4_nat_entry.c

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/****************************************************************************
* net/nat/ipv4_nat_entry.c
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 <debug.h>
#include <stdint.h>
#include <nuttx/clock.h>
#include <nuttx/hashtable.h>
#include <nuttx/kmalloc.h>
#include <nuttx/nuttx.h>
#include "nat/nat.h"
#include "netlink/netlink.h"
#ifdef CONFIG_NET_NAT44
/****************************************************************************
* Private Data
****************************************************************************/
static DECLARE_HASHTABLE(g_nat44_inbound, CONFIG_NET_NAT_HASH_BITS);
static DECLARE_HASHTABLE(g_nat44_outbound, CONFIG_NET_NAT_HASH_BITS);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: ipv4_nat_inbound_key
*
* Description:
* Create an inbound hash key for NAT.
*
****************************************************************************/
static inline uint32_t ipv4_nat_inbound_key(in_addr_t external_ip,
uint16_t external_port,
uint8_t protocol)
{
return NTOHL(external_ip) ^ /* external ip may different in higher bits. */
((uint32_t)protocol << 16) ^ external_port;
}
/****************************************************************************
* Name: ipv4_nat_outbound_key
*
* Description:
* Create an outbound hash key for NAT.
*
****************************************************************************/
static inline uint32_t ipv4_nat_outbound_key(in_addr_t local_ip,
uint16_t local_port,
uint8_t protocol)
{
return NTOHL(local_ip) ^ /* NTOHL makes sure difference is in lower bits. */
((uint32_t)protocol << 8) ^ ((uint32_t)local_port << 16);
}
/****************************************************************************
* Name: ipv4_nat_entry_refresh
*
* Description:
* Refresh a NAT entry, update its expiration time.
*
* Input Parameters:
* entry - The entry to refresh.
*
****************************************************************************/
static void ipv4_nat_entry_refresh(FAR ipv4_nat_entry_t *entry)
{
entry->expire_time = nat_expire_time(entry->protocol);
}
/****************************************************************************
* Name: ipv4_nat_entry_create
*
* Description:
* Create a NAT entry and insert into entry list.
*
* Input Parameters:
* protocol - The L4 protocol of the packet.
* external_ip - The external ip of the packet.
* external_port - The external port of the packet.
* local_ip - The local ip of the packet.
* local_port - The local port of the packet.
* peer_ip - The peer ip of the packet.
* peer_port - The peer port of the packet.
*
* Returned Value:
* Pointer to entry on success; null on failure
*
****************************************************************************/
static FAR ipv4_nat_entry_t *
ipv4_nat_entry_create(uint8_t protocol,
in_addr_t external_ip, uint16_t external_port,
in_addr_t local_ip, uint16_t local_port,
in_addr_t peer_ip, uint16_t peer_port)
{
FAR ipv4_nat_entry_t *entry = kmm_malloc(sizeof(ipv4_nat_entry_t));
if (entry == NULL)
{
nwarn("WARNING: Failed to allocate IPv4 NAT entry\n");
return NULL;
}
entry->protocol = protocol;
entry->external_ip = external_ip;
entry->external_port = external_port;
entry->local_ip = local_ip;
entry->local_port = local_port;
#ifdef CONFIG_NET_NAT44_SYMMETRIC
entry->peer_ip = peer_ip;
entry->peer_port = peer_port;
#endif
ipv4_nat_entry_refresh(entry);
hashtable_add(g_nat44_inbound, &entry->hash_inbound,
ipv4_nat_inbound_key(external_ip, external_port, protocol));
hashtable_add(g_nat44_outbound, &entry->hash_outbound,
ipv4_nat_outbound_key(local_ip, local_port, protocol));
#ifdef CONFIG_NETLINK_NETFILTER
netlink_conntrack_notify(IPCTNL_MSG_CT_NEW, PF_INET, entry);
#endif
return entry;
}
/****************************************************************************
* Name: ipv4_nat_entry_delete
*
* Description:
* Delete a NAT entry and remove from entry list.
*
* Input Parameters:
* entry - The entry to remove.
*
****************************************************************************/
static void ipv4_nat_entry_delete(FAR ipv4_nat_entry_t *entry)
{
ninfo("INFO: Removing NAT44 entry proto=%" PRIu8
", local=%" PRIx32 ":%" PRIu16 ", external=:%" PRIu16 "\n",
entry->protocol, entry->local_ip, entry->local_port,
entry->external_port);
hashtable_delete(g_nat44_inbound, &entry->hash_inbound,
ipv4_nat_inbound_key(entry->external_ip,
entry->external_port,
entry->protocol));
hashtable_delete(g_nat44_outbound, &entry->hash_outbound,
ipv4_nat_outbound_key(entry->local_ip,
entry->local_port,
entry->protocol));
#ifdef CONFIG_NETLINK_NETFILTER
netlink_conntrack_notify(IPCTNL_MSG_CT_DELETE, PF_INET, entry);
#endif
kmm_free(entry);
}
/****************************************************************************
* Name: ipv4_nat_reclaim_entry
*
* Description:
* Try reclaim all expired NAT entries.
* Only works after every CONFIG_NET_NAT_ENTRY_RECLAIM_SEC (low frequency).
*
* Although expired entries will be automatically reclaimed when matching
* inbound/outbound entries, there might be some situations that entries
* will be kept in memory, e.g. big hashtable with only a few connections.
*
* Assumptions:
* NAT is initialized.
*
****************************************************************************/
#if CONFIG_NET_NAT_ENTRY_RECLAIM_SEC > 0
static void ipv4_nat_reclaim_entry_cb(FAR ipv4_nat_entry_t *entry,
FAR void *arg)
{
int32_t current_time = *(FAR int32_t *)arg;
if (entry->expire_time - current_time <= 0)
{
ipv4_nat_entry_delete(entry);
}
}
static void ipv4_nat_reclaim_entry(int32_t current_time)
{
static int32_t next_reclaim_time = CONFIG_NET_NAT_ENTRY_RECLAIM_SEC;
if (next_reclaim_time - current_time <= 0)
{
ninfo("INFO: Reclaiming all expired NAT44 entries.\n");
ipv4_nat_entry_foreach(ipv4_nat_reclaim_entry_cb, &current_time);
next_reclaim_time = current_time + CONFIG_NET_NAT_ENTRY_RECLAIM_SEC;
}
}
#else
# define ipv4_nat_reclaim_entry(t)
#endif
/****************************************************************************
* Name: ipv4_nat_entry_clear_cb
*
* Description:
* Clear an entry related to dev. Called when NAT will be disabled on
* any device.
*
****************************************************************************/
static void ipv4_nat_entry_clear_cb(FAR ipv4_nat_entry_t *entry,
FAR void *arg)
{
FAR struct net_driver_s *dev = arg;
if (net_ipv4addr_cmp(entry->external_ip, dev->d_ipaddr))
{
ipv4_nat_entry_delete(entry);
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: ipv4_nat_entry_clear
*
* Description:
* Clear all entries related to dev. Called when NAT will be disabled on
* any device.
*
* Input Parameters:
* dev - The device on which NAT entries will be cleared.
*
* Assumptions:
* NAT is initialized.
*
****************************************************************************/
void ipv4_nat_entry_clear(FAR struct net_driver_s *dev)
{
ninfo("INFO: Clearing all NAT44 entries for %s\n", dev->d_ifname);
ipv4_nat_entry_foreach(ipv4_nat_entry_clear_cb, dev);
}
/****************************************************************************
* Name: ipv4_nat_entry_foreach
*
* Description:
* Call the callback function for each NAT entry.
*
* Input Parameters:
* cb - The callback function.
* arg - The argument to pass to the callback function.
*
****************************************************************************/
void ipv4_nat_entry_foreach(ipv4_nat_entry_cb_t cb, FAR void *arg)
{
FAR hash_node_t *p;
FAR hash_node_t *tmp;
int i;
hashtable_for_every_safe(g_nat44_inbound, p, tmp, i)
{
FAR ipv4_nat_entry_t *entry =
container_of(p, ipv4_nat_entry_t, hash_inbound);
cb(entry, arg);
}
}
/****************************************************************************
* Name: ipv4_nat_inbound_entry_find
*
* Description:
* Find the inbound entry in NAT entry list.
*
* Input Parameters:
* protocol - The L4 protocol of the packet.
* external_ip - The external ip of the packet, supports INADDR_ANY.
* external_port - The external port of the packet.
* peer_ip - The peer ip of the packet.
* peer_port - The peer port of the packet.
* refresh - Whether to refresh the selected entry.
*
* Returned Value:
* Pointer to entry on success; null on failure
*
****************************************************************************/
FAR ipv4_nat_entry_t *
ipv4_nat_inbound_entry_find(uint8_t protocol, in_addr_t external_ip,
uint16_t external_port, in_addr_t peer_ip,
uint16_t peer_port, bool refresh)
{
FAR hash_node_t *p;
FAR hash_node_t *tmp;
bool skip_ip = net_ipv4addr_cmp(external_ip, INADDR_ANY);
#ifdef CONFIG_NET_NAT44_SYMMETRIC
bool skip_peer = net_ipv4addr_cmp(peer_ip, INADDR_ANY);
#endif
int32_t current_time = TICK2SEC(clock_systime_ticks());
ipv4_nat_reclaim_entry(current_time);
hashtable_for_every_possible_safe(g_nat44_inbound, p, tmp,
ipv4_nat_inbound_key(external_ip, external_port, protocol))
{
FAR ipv4_nat_entry_t *entry =
container_of(p, ipv4_nat_entry_t, hash_inbound);
/* Remove expired entries. */
if (entry->expire_time - current_time <= 0)
{
ipv4_nat_entry_delete(entry);
continue;
}
if (entry->protocol == protocol &&
(skip_ip || net_ipv4addr_cmp(entry->external_ip, external_ip)) &&
entry->external_port == external_port
#ifdef CONFIG_NET_NAT44_SYMMETRIC
&& (skip_peer || (net_ipv4addr_cmp(entry->peer_ip, peer_ip) &&
entry->peer_port == peer_port))
#endif
)
{
if (refresh)
{
ipv4_nat_entry_refresh(entry);
}
return entry;
}
}
if (refresh) /* false = a test of whether entry exists, no need to warn */
{
nwarn("WARNING: Failed to find IPv4 inbound NAT entry for "
"proto=%" PRIu8 ", external=%" PRIx32 ":%" PRIu16 "\n",
protocol, external_ip, external_port);
}
return NULL;
}
/****************************************************************************
* Name: ipv4_nat_outbound_entry_find
*
* Description:
* Find the outbound entry in NAT entry list. Create one if corresponding
* entry does not exist.
*
* Input Parameters:
* dev - The device on which the packet will be sent.
* protocol - The L4 protocol of the packet.
* local_ip - The local ip of the packet.
* local_port - The local port of the packet.
* peer_ip - The peer ip of the packet.
* peer_port - The peer port of the packet.
* try_create - Try create the entry if no entry found.
*
* Returned Value:
* Pointer to entry on success; null on failure
*
****************************************************************************/
FAR ipv4_nat_entry_t *
ipv4_nat_outbound_entry_find(FAR struct net_driver_s *dev, uint8_t protocol,
in_addr_t local_ip, uint16_t local_port,
in_addr_t peer_ip, uint16_t peer_port,
bool try_create)
{
FAR hash_node_t *p;
FAR hash_node_t *tmp;
uint16_t external_port;
int32_t current_time = TICK2SEC(clock_systime_ticks());
ipv4_nat_reclaim_entry(current_time);
hashtable_for_every_possible_safe(g_nat44_outbound, p, tmp,
ipv4_nat_outbound_key(local_ip, local_port, protocol))
{
FAR ipv4_nat_entry_t *entry =
container_of(p, ipv4_nat_entry_t, hash_outbound);
/* Remove expired entries. */
if (entry->expire_time - current_time <= 0)
{
ipv4_nat_entry_delete(entry);
continue;
}
if (entry->protocol == protocol &&
net_ipv4addr_cmp(entry->external_ip, dev->d_ipaddr) &&
net_ipv4addr_cmp(entry->local_ip, local_ip) &&
entry->local_port == local_port
#ifdef CONFIG_NET_NAT44_SYMMETRIC
&& net_ipv4addr_cmp(entry->peer_ip, peer_ip) &&
entry->peer_port == peer_port
#endif
)
{
ipv4_nat_entry_refresh(entry);
return entry;
}
}
if (!try_create)
{
return NULL;
}
/* Failed to find the entry, create one. */
ninfo("INFO: Failed to find IPv4 outbound NAT entry for "
"proto=%" PRIu8 ", local=%" PRIx32 ":%" PRIu16 ", try create one.\n",
protocol, local_ip, local_port);
external_port = nat_port_select(dev, PF_INET, protocol,
(FAR union ip_addr_u *)&dev->d_ipaddr, local_port);
if (!external_port)
{
nwarn("WARNING: Failed to find an available port!\n");
return NULL;
}
return ipv4_nat_entry_create(protocol, dev->d_ipaddr, external_port,
local_ip, local_port, peer_ip, peer_port);
}
#endif /* CONFIG_NET_NAT44 */
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