ipfw port lookup table patch for review

[Ganbold]

Hi,

I thought it might be useful to have port lookup table similar to 
existing IP lookup table
in ipfw and I have made patch for that.

The downside of the patch so far I'm seeing is the port entries are in 
linked list
(no limitation yet, memory overhead), not sorted and it uses linear search
to match (could be slow when lot of entries).

Just after I've made the patch I saw
http://www.freebsd.org/cgi/query-pr.cgi?pr=121807&cat= . :(

I agree with PR's reply however for small number of port entries I thought
this functionality is quite useful. It gives benefit like no need to 
modify existing rule,
adding/deleting port entries is easy.

I did some small tests and it seems like working.

Patches are at:
http://people.freebsd.org/~ganbold/ipfw_port_table/

The output of some usage samples is at:
http://people.freebsd.org/~ganbold/ipfw_port_table/ipfw_port_table_usage_sample.txt

Patches can be successfully applied to CURRENT. Didn't test RELENG_7 due to
no RELENG_7  PC :)
Please let me know your thoughts. I'm happy to discuss to improve the patch.
Correct me if I'm doing something wrong here.

thanks,

Ganbold