Re: FreeBSD's RST validation

[bmah () CA Sandia GOV (Bruce A. Mah)]

If memory serves me right, Don Lewis wrote:

> Now that I look at this change some more, I think your added tests are
> a NOP because of the code just above this:
>
>               if ((tiflags & TH_ACK) &&
>                     (SEQ_LEQ(ti->ti_ack, tp->iss) ||
>                      SEQ_GT(ti->ti_ack, tp->snd_max))) {
>                       [ snip comment ]
>                         if (taop->tao_ccsent != 0)
>                                 goto drop;
>                         else
>                                 goto dropwithreset;
>
> If the ACK is outside the window, the packet will already have been
> dropped before we even look for the RST flag.

Ah, yes.  You're absolutely right.  So it appears only the second of the
original patches is useful (if it's correct, that is).

This was a good day for me...I learned something.

Thanks!

Bruce.