The symmetric NAT limits one external port to be used with only one peer ip:port.
Note:
1. To avoid using too much #ifdef, we're always passing peer_ip and peer_port as arguments, but won't use them under full cone NAT, let the compiler optimize them.
2. We need to find port binding without peer ip:port, so don't add peer ip:port into hash key.
3. Symmetric NAT needs to *select another external port if a port is used by any other NAT entry*, this behavior is exactly same as Full Cone NAT, so we don't need to change anything related to `ipv4_nat_port_inuse`.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
1. Don't assert on IGMP inside ICMP, just ignore it.
2. Check we have full IP header inside ICMP payload before accessing it.
3. `inner_l4hdrbak` need to be `L4_MAXHDRLEN`, not `L4_MAXHDRLEN/2`.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
1.
ipfrag/ipv4_frag.c: In function ‘ipv4_fragin’:
ipfrag/ipv4_frag.c:184:22: warning: ‘head’ may be used uninitialized in this function [-Wmaybe-uninitialized]
184 | ipv4->len[1] = head->io_pktlen & 0xff;
| ~~~~^~~~~~~~~~~
ipfrag/ipv4_frag.c:123:21: note: ‘head’ was declared here
123 | FAR struct iob_s *head;
| ^~~~
2.
devif/ipv6_input.c: In function ‘ipv6_in’:
devif/ipv6_input.c:60:33: error: ‘TCPIPv6BUF’ undeclared (first use in this function); did you mean ‘UDPIPv6BUF’?
60 | #define PAYLOAD ((FAR uint8_t *)TCPIPv6BUF)
| ^~~~~~~~~~
3.
nat/ipv4_nat.c: In function ‘ipv4_nat_inbound_icmp’:
nat/ipv4_nat.c:67:30: error: ‘TCP_HDRLEN’ undeclared (first use in this function); did you mean ‘UDP_HDRLEN’?
67 | ((proto) == IP_PROTO_TCP ? TCP_HDRLEN : \
| ^~~~~~~~~~
nat/ipv4_nat.c:323:47: note: in expansion of macro ‘L4_HDRLEN’
323 | inner_l4hdrlen = MIN(inner_l4len, L4_HDRLEN(inner->proto));
| ^~~~~~~~~
Signed-off-by: chao an <anchao@xiaomi.com>
Split out ipv4_nat_in/outbound_internal which returns entry instead of error code, for later ICMP error types, does not change any current logic.
Reason: Outer packet doesn't have information of port, so we need to find entry by inner packet, and apply the entry to outer packet.
| Outer Packet: SRC = Peer IP<No Port>, DST = External IP<No Port> |
| Inner Packet: SRC = External IP:Port, DST = Peer IP:Port |
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
This commit is for later ICMP error types processing, and does not change any current logic.
Reason for supporting both side of modification is that an inbound ICMP Error MSG may carry original packet like this:
| IP HDR: SRC = Peer IP, DST = External IP |
| ICMP HDR: ERROR MSG |
| <Origin> IP HDR: SRC = External IP, DST = Peer IP |
| <Origin> L4 HDR: SRC = External Port, DST = Peer Port |
So we need to support inbound translation (External -> Local) on SRC or DST of each header.
And so do the outbound direction.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
Support ICMP ECHO REQUEST & REPLY. Id of ICMP is processed like port of TCP in NAT. However, our ICMP stack doesn't have a method to manage id allocation like tcp_selectport(), the id is set by apps (like icmp_ping.c) without conflict avoidance, so not adding such conflict avoidance logic to ICMP stack when implementing NAT.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
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>
