Date: Mon, 10 Jan 2005 03:56:31 -0600 (CST) From: Mike Silbersack <silby@silby.com> To: Don Lewis <truckman@FreeBSD.org> Cc: net@FreeBSD.org Subject: Re: Slipping in the window update Message-ID: <20050110034422.C9716@odysseus.silby.com> In-Reply-To: <200501100850.j0A8o6FY019623@gw.catspoiler.org> References: <200501100850.j0A8o6FY019623@gw.catspoiler.org>
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On Mon, 10 Jan 2005, Don Lewis wrote:
> Now that I've looked at the above case, it looks to me like your
> suggested patch might affect the response to a legitimate duplicate SYN.
> It will definitely follow a different code path.
You're right, I neglected to handle the duplicate SYN case.
Couldn't we centralize all SYN handling right after trimthenstep6:?
We could do something there like
if (th->th_seq != tp->irs) {
goto dropafterack; /* Or however we handle these bad syns */
} else {
thflags &= ~TH_SYN;
th->th_seq++;
if (th->th_urp > 1)
th->th_urp--;
else
thflags &= ~TH_URG;
todrop--;
}
And then we could tear out all the two places TH_SYN is mentioned below,
the place I copied from, and the place where there the tcp_drop() is.
If we made that change, then we'd still be doing only one check for
TH_SYN, but the code would be a lot easier to comprehend.
Mike "Silby" Silbersack
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