nuttx/net/nat/nat.h
Zhe Weng b595430578 net: add basic NAT workflow
Add basic functions for NAT (NAPT), remaining some logic unimplemented (UDP, ICMP, port assignment, etc). NAT for TCP can work now (unless port conflicts).
Outbound: LAN ->  Forward  ->  NAT(only if targeting at WAN)  -> WAN
Inbound:  WAN ->  NAT(only from WAN, change dest) -> Forward  -> LAN

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
2022-11-11 14:36:55 +08:00

200 lines
6.8 KiB
C

/****************************************************************************
* net/nat/nat.h
*
* 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.
*
****************************************************************************/
#ifndef __NET_NAT_NAT_H
#define __NET_NAT_NAT_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <netinet/in.h>
#include <nuttx/net/ip.h>
#include <nuttx/net/netdev.h>
#if defined(CONFIG_NET_NAT) && defined(CONFIG_NET_IPv4)
/****************************************************************************
* Public Types
****************************************************************************/
struct ipv4_nat_entry
{
/* Support for single-linked lists.
*
* TODO: Implement a general hash table, and use it to optimize performance
* here.
*/
FAR struct ipv4_nat_entry *flink;
/* Local Network External Network
* |----------------|
* <local IP, | | <external IP, <peer IP,
* -----------| |-----------------------------
* local port> | | external port> peer port>
* |----------------|
*
* Full cone NAT on single WAN only need to save local ip:port and external
* port. For ICMP, save id in port field.
*/
in_addr_t local_ip; /* IP address of the local (private) host. */
uint16_t local_port; /* Port of the local (private) host. */
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. */
};
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: ipv4_nat_enable
*
* Description:
* Enable NAT function on a network device.
*
* Input Parameters:
* dev - The device on which the outbound packets will be masqueraded.
*
* Returned Value:
* Zero is returned if NAT function is successfully enabled on the device;
* A negated errno value is returned if failed.
*
* Assumptions:
* NAT will only be enabled on at most one device.
*
* Limitations:
* External ports are not isolated between devices yet, so if NAT is
* enabled on more than one device, an external port used on one device
* will also be used by same local ip:port on another device.
*
****************************************************************************/
int ipv4_nat_enable(FAR struct net_driver_s *dev);
/****************************************************************************
* Name: ipv4_nat_disable
*
* Description:
* Disable NAT function on a network device.
*
* Input Parameters:
* dev - The device on which the NAT function will be disabled.
*
* Returned Value:
* Zero is returned if NAT function is successfully disabled on the device;
* A negated errno value is returned if failed.
*
****************************************************************************/
int ipv4_nat_disable(FAR struct net_driver_s *dev);
/****************************************************************************
* Name: ipv4_nat_inbound
*
* Description:
* Check if a received packet belongs to a NAT entry. If so, translate it.
*
* Input Parameters:
* dev - The device on which the packet is received.
* ipv4 - Points to the IPv4 header with dev->d_buf.
*
* Returned Value:
* Zero is returned if NAT is successfully applied, or is not enabled for
* this packet;
* A negated errno value is returned if error occured.
*
****************************************************************************/
int ipv4_nat_inbound(FAR struct net_driver_s *dev,
FAR struct ipv4_hdr_s *ipv4);
/****************************************************************************
* Name: ipv4_nat_outbound
*
* Description:
* Check if we want to perform NAT with this outbound packet before sending
* it. If so, translate it.
*
* Input Parameters:
* dev - The device on which the packet will be sent.
* ipv4 - Points to the IPv4 header to be filled into dev->d_buf later.
*
* Returned Value:
* Zero is returned if NAT is successfully applied, or is not enabled for
* this packet;
* A negated errno value is returned if error occured.
*
****************************************************************************/
int ipv4_nat_outbound(FAR struct net_driver_s *dev,
FAR struct ipv4_hdr_s *ipv4);
/****************************************************************************
* 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_port - The external port of the packet.
*
* Returned Value:
* Pointer to entry on success; null on failure
*
****************************************************************************/
FAR struct ipv4_nat_entry *
ipv4_nat_inbound_entry_find(uint8_t protocol, uint16_t external_port);
/****************************************************************************
* 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:
* protocol - The L4 protocol of the packet.
* local_ip - The local ip of the packet.
* local_port - The local port of the packet.
*
* Returned Value:
* Pointer to entry on success; null on failure
*
****************************************************************************/
FAR struct ipv4_nat_entry *
ipv4_nat_outbound_entry_find(uint8_t protocol, in_addr_t local_ip,
uint16_t local_port);
#endif /* CONFIG_NET_NAT && CONFIG_NET_IPv4 */
#endif /* __NET_NAT_NAT_H */