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Date:      Thu, 12 Sep 2002 14:06:33 -0700 (PDT)
From:      John Polstra <jdp@polstra.com>
To:        net@freebsd.org
Cc:        soheil_h_y@hotmail.com
Subject:   Re: computing the Ack Seq. No.
Message-ID:  <200209122106.g8CL6XvX033841@vashon.polstra.com>
In-Reply-To: <F129kqC5EtrUVYKkpLT000003bd@hotmail.com>
References:  <F129kqC5EtrUVYKkpLT000003bd@hotmail.com>

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In article <F129kqC5EtrUVYKkpLT000003bd@hotmail.com>,
soheil h <soheil_h_y@hotmail.com> wrote:
> Hi list
> accourding to my code
> does anyone think that i must make the th_off ntohsed ?????????
> NTOHS(th_off)  ?????????
> Please verify me
> i know that i didn't do that
> thanx

No, th_off is not a multibyte field, so you don't have to byte swap
it.  But you do have to byte swap the sequence number (ntohl), the
ack (ntohl), and the ip length (ntohs) before you do calculations on
them.  And then you have to swap the results back (htonl, htons)
before you send them out the network.

John
-- 
  John Polstra
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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