Re: [IPv6] [Last-Call] Artart last call review of draft-ietf-6man-rfc6874bis-02

On Sun, Mar 26, 2023 at 4:58 PM David Farmer <[email protected]> wrote:

>
>
> On Sun, Mar 26, 2023 at 17:51 Rob Sayre <[email protected]> wrote:
>
>> On Sun, Mar 26, 2023 at 3:44 PM Brian E Carpenter <
>> [email protected]> wrote:
>>
>>> In what way does it "break" existing parsers? They simply return an
>>> error. Why is that a problem? As discussed at
>>> https://www.ietf.org/archive/id/draft-ietf-6man-rfc6874bis-05.html#section-4-1,
>>> this is completely compatible with stepwise deployment as and when needed.
>>>
>>> Yes, it becomes a feature request for existing parsers. And it will only
>>> get implemented when the need is irresistible. No different from any other
>>> feature request.
>>>
>>
>> I think the general issue is that some of them are looking for the
>> "authority" component, and relying on the uniform syntax here. Maybe it's
>> worth breaking that for this feature, but it's not a made-up issue. I still
>> look at it and think "why?", though.
>>
>
> So, I’ll bite, why does this syntax interfere with?
>
> If anything, because IPv6 literals with Zone IDs are contained within
> square parentheses “[“,”]”, therefore determining the authority should be
> easy.
>
> Example:
> http://[fe80::1234%en0]:8080/path-p1/p2
>
> Please explain how it interferes with determining a URI’s “authority”
> component.
>

It's not allowed in the original grammar. This is why the draft rewrites
the "IP-literal" rule to allow for a zone identifier. I think the catch
here is that the chosen delimiter is "%", and that causes problems for URI
parsers that are not updated for this issue. You could use a character that
would not have this problem, as Appendix A describes.

It's possible to change the parsers, but I think the nature of the
objections are that you can't actually change all of them. Basically, "%"
is probably the worst possible choice.

thanks,
Rob

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