Verify ACK packet in handshake in kernel module (access TCP state table)

[Swarm]

First time emailing to this mailing list so please let me know if I made 
a mistake in how I sent it. I'm trying to receive a notification from 
the kernel once it verifies an ACK packet in a handshake. Problem is, 
there is no API or kernel resource I've seen that supports this feature 
for both syncookies and normal handshakes. Where exactly in the kernel 
does the ACK get verified? If there isn't a way to be notified of it, 
where should I start adding that feature into the kernel?