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net/nat: Add TCP entry expiration logic 

Add TCP entry expiration logic for NAT, with entries changed from sq to dq for fast removal.

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
This commit is contained in:
Zhe Weng 2022-11-01 18:13:50 +08:00 committed by Xiang Xiao
parent 0a4e01d712
commit 8239ddeef4
5 changed files with 122 additions and 10 deletions
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4
include/nuttx/queue.h
View File

@ -158,6 +158,10 @@
#define sq_for_every(q, p) \
for ((p) = (q)->head; (p) != NULL; (p) = (p)->flink)
#define sq_for_every_safe(q, p, tmp) \
for((p) = (q)->head, (tmp) = (p) ? (p)->flink : NULL; \
(p) != NULL; (p) = (tmp), (tmp) = (p) ? (p)->flink : NULL)
#define sq_rem(p, q) \
do \
{ \

10
net/nat/Kconfig
View File

@ -9,3 +9,13 @@ config NET_NAT
depends on NET_IPFORWARD
---help---
Enable or disable Network Address Translation (NAT) function.
config NET_NAT_TCP_EXPIRE_SEC
int "TCP NAT entry expiration seconds"
default 86400
depends on NET_NAT
---help---
The expiration time for idle TCP entry in NAT.
Note: The default value 86400 is suggested by RFC2663, Section 2.6,
Page 5.

4
net/nat/ipv4_nat.c
View File

@ -79,7 +79,7 @@ static int ipv4_nat_inbound_tcp(FAR struct ipv4_hdr_s *ipv4)
FAR struct tcp_hdr_s *tcp =
(FAR struct tcp_hdr_s *)((FAR uint8_t *)ipv4 + iphdrlen);
FAR struct ipv4_nat_entry *entry =
ipv4_nat_inbound_entry_find(IP_PROTO_TCP, tcp->destport);
ipv4_nat_inbound_entry_find(IP_PROTO_TCP, tcp->destport, true);
if (!entry)
{
/* Inbound without entry is OK (e.g. towards NuttX itself), skip NAT. */
@ -340,7 +340,7 @@ int ipv4_nat_outbound(FAR struct net_driver_s *dev,
bool ipv4_nat_port_inuse(uint8_t protocol, in_addr_t ip, uint16_t port)
{
FAR struct ipv4_nat_entry *entry =
ipv4_nat_inbound_entry_find(protocol, port);
ipv4_nat_inbound_entry_find(protocol, port, false);
/* Not checking ip is enough for single NAT device, may save external_ip in
* entry for multiple device support in future.

105
net/nat/ipv4_nat_entry.c
View File

@ -26,6 +26,7 @@
#include <debug.h>
#include <nuttx/clock.h>
#include <nuttx/kmalloc.h>
#include <nuttx/queue.h>
@ -37,7 +38,7 @@
* Private Data
****************************************************************************/
static sq_queue_t g_entries;
static dq_queue_t g_entries;
/****************************************************************************
* Private Functions
@ -69,6 +70,45 @@ static uint16_t ipv4_nat_select_port(uint8_t protocol, uint16_t local_port)
return local_port;
}
/****************************************************************************
* 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 struct ipv4_nat_entry *entry)
{
switch (entry->protocol)
{
#ifdef CONFIG_NET_TCP
case IP_PROTO_TCP:
/* NOTE: According to RFC2663, Section 2.6, Page 5, we can reduce the
* time to 4min if we have received FINs from both side of one
* connection, and keep 24h for other TCP connections. However, full
* cone NAT may have multiple connections on one entry, so this
* optimization may not work and we only use one expiration time.
*/
entry->expire_time = TICK2SEC(clock_systime_ticks()) +
CONFIG_NET_NAT_TCP_EXPIRE_SEC;
break;
#endif
#ifdef CONFIG_NET_UDP
# warning Missing logic
#endif
#ifdef CONFIG_NET_ICMP
# warning Missing logic
#endif
}
}
/****************************************************************************
* Name: ipv4_nat_entry_create
*
@ -103,10 +143,33 @@ ipv4_nat_entry_create(uint8_t protocol, uint16_t external_port,
entry->local_ip = local_ip;
entry->local_port = local_port;
sq_addfirst((FAR sq_entry_t *)entry, &g_entries);
ipv4_nat_entry_refresh(entry);
dq_addfirst((FAR dq_entry_t *)entry, &g_entries);
return entry;
}
/****************************************************************************
* Name: ipv4_nat_entry_delete
*
* Description:
* Delete a NAT entry and remove from entry list.
*
* Input Parameters:
* entry - The entry to remove.
*
****************************************************************************/
void ipv4_nat_entry_delete(FAR struct ipv4_nat_entry *entry)
{
ninfo("INFO: Removing NAT entry proto=%d, local=%x:%d, external=:%d\n",
entry->protocol, entry->local_ip, entry->local_port,
entry->external_port);
dq_rem((FAR dq_entry_t *)entry, &g_entries);
kmm_free(entry);
}
/****************************************************************************
* Public Functions
****************************************************************************/
@ -120,6 +183,7 @@ ipv4_nat_entry_create(uint8_t protocol, uint16_t external_port,
* Input Parameters:
* protocol - The L4 protocol of the packet.
* external_port - The external port of the packet.
* refresh - Whether to refresh the selected entry.
*
* Returned Value:
* Pointer to entry on success; null on failure
@ -127,17 +191,35 @@ ipv4_nat_entry_create(uint8_t protocol, uint16_t external_port,
****************************************************************************/
FAR struct ipv4_nat_entry *
ipv4_nat_inbound_entry_find(uint8_t protocol, uint16_t external_port)
ipv4_nat_inbound_entry_find(uint8_t protocol, uint16_t external_port,
bool refresh)
{
FAR sq_entry_t *p;
sq_for_every(&g_entries, p)
FAR sq_entry_t *tmp;
uint32_t current_time = TICK2SEC(clock_systime_ticks());
sq_for_every_safe((FAR sq_queue_t *)&g_entries, p, tmp)
{
FAR struct ipv4_nat_entry *entry = (FAR struct ipv4_nat_entry *)p;
/* Remove expired entries. */
if (entry->expire_time < current_time)
{
ipv4_nat_entry_delete(entry);
continue;
}
if (entry->protocol == protocol &&
entry->external_port == external_port)
{
/* TODO: Use hash table, or move recent node to head. */
if (refresh)
{
ipv4_nat_entry_refresh(entry);
}
return entry;
}
}
@ -169,15 +251,28 @@ ipv4_nat_outbound_entry_find(uint8_t protocol, in_addr_t local_ip,
uint16_t local_port)
{
FAR sq_entry_t *p;
sq_for_every(&g_entries, p)
FAR sq_entry_t *tmp;
uint32_t current_time = TICK2SEC(clock_systime_ticks());
sq_for_every_safe((FAR sq_queue_t *)&g_entries, p, tmp)
{
FAR struct ipv4_nat_entry *entry = (FAR struct ipv4_nat_entry *)p;
/* Remove expired entries. */
if (entry->expire_time < current_time)
{
ipv4_nat_entry_delete(entry);
continue;
}
if (entry->protocol == protocol &&
net_ipv4addr_cmp(entry->local_ip, local_ip) &&
entry->local_port == local_port)
{
/* TODO: Use hash table, or move recent node to head. */
ipv4_nat_entry_refresh(entry);
return entry;
}
}

9
net/nat/nat.h
View File

@ -43,13 +43,14 @@
struct ipv4_nat_entry
{
/* Support for single-linked lists.
/* Support for doubly-linked lists.
*
* TODO: Implement a general hash table, and use it to optimize performance
* here.
*/
FAR struct ipv4_nat_entry *flink;
FAR struct ipv4_nat_entry *blink;
/* Local Network External Network
* |----------------|
@ -67,7 +68,7 @@ struct ipv4_nat_entry
uint16_t external_port; /* The external port of local (private) host. */
uint8_t protocol; /* L4 protocol (TCP, UDP etc). */
/* TODO: Timeout check and remove outdated entry. */
uint32_t expire_time; /* The expiration time of this entry. */
};
/****************************************************************************
@ -184,6 +185,7 @@ bool ipv4_nat_port_inuse(uint8_t protocol, in_addr_t ip, uint16_t port);
* Input Parameters:
* protocol - The L4 protocol of the packet.
* external_port - The external port of the packet.
* refresh - Whether to refresh the selected entry.
*
* Returned Value:
* Pointer to entry on success; null on failure
@ -191,7 +193,8 @@ bool ipv4_nat_port_inuse(uint8_t protocol, in_addr_t ip, uint16_t port);
****************************************************************************/
FAR struct ipv4_nat_entry *
ipv4_nat_inbound_entry_find(uint8_t protocol, uint16_t external_port);
ipv4_nat_inbound_entry_find(uint8_t protocol, uint16_t external_port,
bool refresh);
/****************************************************************************
* Name: ipv4_nat_outbound_entry_find