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Re: chunk-extensions

From: Julian Reschke <julian.reschke@gmx.de>
Date: Sun, 15 Sep 2013 14:41:01 +0200
Message-ID: <5235AADD.8080708@gmx.de>
To: Willy Tarreau <w@1wt.eu>
CC: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
On 2013-09-15 11:23, Willy Tarreau wrote:
> On Sun, Sep 15, 2013 at 10:44:32AM +0200, Julian Reschke wrote:
>> On 2013-09-15 08:21, Willy Tarreau wrote:
>>> On Sun, Sep 15, 2013 at 04:01:01PM +1000, Mark Nottingham wrote:
>>>> Document that they may not be persisted beyond a, because chunking (and
>>>> therefore extensions) don't have any semantic in the message itself.
>>>> Furthermore, that they're not available in most implementations.
>>>
>>> Probably it would be easier to remind that just like chunks themselves,
>>> they're connection-specific, since any intermediary is allowed to
>>> rechunk differently. It is also obvious that a compressing gateway
>>> will rechunk for example.
>>
>> Can you suggest concrete text?
>
> Just doing a quick attempt :
>
> @p1-23#4.1
> -   Chunk extensions within the chunked transfer coding are deprecated.
> -   Senders SHOULD NOT send chunk-ext.  Definition of new chunk
> -   extensions is discouraged.
> +   The current version of the HTTP specification defines no specific
> +   use for the chunk extensions. When use of chunk extensions is
> +   considered to transport anything (for example, chunks signatures),
> +   care must be taken about the nature of the information present in
> +   these extensions which by definition are hop-by-hop and not
> +   end-to-end, as nothing prevents an intermediary from forwarding a
> +   message with different size chunks, or even dropping or replacing
> +   these extensions as well.
>
> Willy

OK, change proposal:

1673,1675c1673,1677
<  Chunk extensions within the chunked transfer coding are deprecated.
<  A sender SHOULD NOT send chunk-ext.  Definition of new chunk
<  extensions is discouraged.
---
 >  Chunk extensions need to be used carefully because use of chunking
 >  does not have any semantics related to the message; it is by
 >  definition hop-by-hop and thus can be removed/reformatted by any
 >  intermediate.  Furthermore, few implementations expose information
 >  about their contents.

3524,3525c3526,3527
<  header and trailer.  Use of chunk extensions is deprecated, and line
<  folding in them is disallowed.  (Section 4.1)
---
 >  header and trailer.  Line folding in chunk extensions is disallowed.
 >  (Section 4.1)


(<http://trac.tools.ietf.org/wg/httpbis/trac/attachment/ticket/343/343.2.diff>)

Best regards, Julian
Received on Sunday, 15 September 2013 12:41:33 UTC

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