Make nat_port_select() return an error code and report the selected
external port through an output parameter.
This separates selection failure from the valid ICMP echo identifier
value zero, so outbound NAT entry creation no longer rejects ICMP echo
requests that use id zero.
Signed-off-by: Shunchao Hu <ankohuu@gmail.com>
Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.
Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
I found `struct ipv*_nat_entry` is missing `_s` suffix, but the name is too long in some cases, so maybe `ipv*_nat_entry_t` could be better.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
Notes:
1. This version of NAT66 is a stateful one like NAT44, corresponding to Linux's MASQUERADE target of ip6tables. We can support stateless NAT66 & NPTv6 later by slightly modify the address & port selection logic (maybe just match the rules and skip the entry find).
2. We're using same flag `IFF_NAT` for both NAT44 & NAT66 to make control easier. Which means, if we enable NAT, both NAT44 & NAT66 will be enabled. If we don't want one of them, we can just disable that one in Kconfig.
3. Maybe we can accelerate the checksum adjustment by pre-calculate a difference of checksum, and apply it to each packet, instead of calling `net_chksum_adjust` each time. Just a thought, maybe do it later.
4. IP fragment segments on NAT66 connections are not supported yet.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
To prepare for future IPv6 NAT functions.
- Rename common ipv4_nat_xxx to nat_xxx
- Move some common definitions into header
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
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>
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>
