[lwip-devel] ipsec hook advice for LwIP

[Teddy Zhai]

Hi LwIP dev,

In an attempt to add IPSec support for LwIP,

for the ingress path, I plan to use this hook to process IPSec related data.

LWIP_HOOK_IPx_INPUT

However, I dont see the equivalent for the egress path. My current thinking suggests that an output hook could be added at the end of ipX_output processing, for example,

right before the data goes to

netif->output(netif, p, dest);

https://git.savannah.nongnu.org/cgit/lwip.git/tree/src/core/ipv4/ip4.c#n1041

for ip4.

Then, the hook will add all IPSec related data before the packet further sends down.

This does bring another question, how can pbuf at this point guarantees enough space is available to add extra IPSec data?

Thanks a lot for your advice.

Met vriendelijke groet / Best regards.
Teddy