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

Mark Nottingham <mnot@mnot.net> Fri, 23 December 2016 16:39 UTC

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From: Mark Nottingham <mnot@mnot.net>
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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>
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References: <20161213173327.C1F7D1714B@welho-filter2.welho.com> <20161213175419.GA7943@LK-Perkele-V2.elisa-laajakaista.fi> <25434.1481665395@critter.freebsd.dk> <201612140628.uBE6SO3L025885@shell.siilo.fmi.fi> <36792.1481701328@critter.freebsd.dk> <CACweHNDKgWQewZHb=Kz3_2=41M58sY5472Q5OwpqPLxorvkzHQ@mail.gmail.com> <37223.1481707288@critter.freebsd.dk> <3a65ca44-f652-3b14-6d64-46f35b32df57@isode.com> <55880.1481711031@critter.freebsd.dk> <95057a05-6714-9154-8cf8-7cd302c86715@gmx.de> <60914.1481712680@critter.freebsd.dk> <CABkgnnWzOhkznH2HzweNegYo4dDHE+DT0PM=eCSvVr+-Wkup1A@mail.gmail.com> <63340.1481720099@critter.freebsd.dk> <C8F21FA8-8B03-4E9C-B0E8-CD3C9CF028CE@mnot.net> <56063.1482509609@critter.freebsd.dk>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
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Subject: Re: Unicode escape sequence | Re: draft-ietf-httpbis-header-structure-00, unicode range
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> 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>et>, 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/