Verify ACK packets 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?