Getting tcp_sock in tcp_parse_options

[Aaron Isotton <aaron@isotton.com>]

Hello

I am porting a kernel patch and module from 2.4 to 2.6. Part of the
patch implements a new TCP options, so it extends tcp_parse_options.
Since the patch has to maintain a state it adds some new fields to
struct tcp_sock which should then be updated from tcp_parse_options.

I had to notice that using tcp_sk(skb) inside tcp_parse_options always
(or at least in all cases I tested) returns NULL. So, how do I get the
tcp_sock structure associated with the connection in tcp_parse_options?

As a side note: is there any documentation about the Linux TCP/IP stack
(except what's in Documentation/ and the comments)?

Thank you very much,
Aaron