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Re: [hybi] frame length encoding

John Tamplin <jat@google.com> Sun, 22 August 2010 23:07 UTC

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From: John Tamplin <jat@google.com>
Date: Sun, 22 Aug 2010 19:08:00 -0400
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To: shelby@coolpage.com
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Cc: Hybi <hybi@ietf.org>
Subject: Re: [hybi] frame length encoding
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On Sun, Aug 22, 2010 at 6:58 PM, Shelby Moore <shelby@coolpage.com> wrote:

> That forces the receiver to check for the larger size.  See my prior post
> on the multi-core issue, that it would be more efficient in that case if
> the sender honored the maximum.
>
> Why can't the sender honor the agreed maximum size?
>

The receiver will still have to check, because the sender might be an
attacker hoping to take advantage of a receiver that only checks the first 2
bytes of the length while firewalls/etc would have filtered it had it been
correct.  Getting different entities to make different decisions about some
framing of data is a fundamental attack tactic.

-- 
John A. Tamplin
Software Engineer (GWT), Google

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