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Re: Unicode escape sequence | Re: draft-ietf-httpbis-header-structure-00, unicode range

From: Mark Nottingham <mnot@mnot.net>
Date: Fri, 23 Dec 2016 11:36:59 -0500
Cc: Martin Thomson <martin.thomson@gmail.com>, "Julian F. Reschke" <julian.reschke@gmx.de>, Alexey Melnikov <alexey.melnikov@isode.com>, Matthew Kerwin <matthew@kerwin.net.au>, Kari Hurtta <hurtta-ietf@elmme-mailer.org>, Ilari Liusvaara <ilariliusvaara@welho.com>, HTTP working group mailing list <ietf-http-wg@w3.org>, Poul-Henning Kamp <phk@varnish-cache.org>
Message-Id: <2C87FAB2-33B3-44FE-A2FB-EB0BD384E87F@mnot.net>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>

> On 23 Dec. 2016, at 11:13 am, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
> 
> --------
> In message <C8F21FA8-8B03-4E9C-B0E8-CD3C9CF028CE@mnot.net>, Mark Nottingham wri
> tes:
> 
>> And, as discussed previously, there aren't a lot of use cases for 
>> non-ASCII header values in standards (because few have a payload that's 
>> exposed to end users), so the reward for taking that risk is 
>> questionable.
> 
> But isn't that an almost circular[1] argument, when there is no
> safe standardized way to put non-ASCII into header values in the
> first place ?

There is -- RFC5987 encoding. Not pretty or efficient, but implemented and interoperable. Used in Content-Disposition, Link (although not much), and not much else AFAIK (Julian?).

> 
> Anyway, here is my current thinking:
> 
> a) Remove the UTF8 option
> -------------------------
> 
> Having UTF8 as an option for the H1 serialization is unlikely to
> significantly increase the number of paths on which you can use it.
> 
> The subset where it will work, will be the same subset with or without
> our blessing:  End-to-End fully confined and controlled paths.
> 
> 
> b) Add BCP137's recommendation unchanged (%x5C.75.27 4*6HEXDIG %x27)
> --------------------------------------------------------------------
> 
> A number of alternatives have been proposed, but I do not think the
> relatively minor increase in HPACK and H1 afficiency they offer 
> warrants "needlessly multiplying entities"[2].
> 
> 
> Absent really convincing arguments, that will be my next edit.
> 
> Poul-Henning
> 
> 
> [1] "Almost circular" is a lot more complex than most people imagine.
> Highly recommended reading: http://press.princeton.edu/titles/8624.html
> 
> [2] Occams Razor.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.

--
Mark Nottingham   https://www.mnot.net/
Received on Friday, 23 December 2016 16:37:25 UTC

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