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

[Mark Nottingham <[e-mail]>]

> On 23 Dec. 2016, at 11:13 am, Poul-Henning Kamp <[e-mail]> wrote:
> 
> --------
> In message <[e-mail]>, 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
> [e-mail]         | 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/