Re: kernel mailing list permalinks

From: H. Peter Anvin
Date: Tue Aug 06 2013 - 19:06:25 EST

On 08/06/2013 02:55 PM, Anders Larsen wrote:
> On 2013-08-06 23:23, H. Peter Anvin wrote:
>> On 08/06/2013 02:11 PM, Bjorn Helgaas wrote:
>> >>
>> >> The above link is also a good example of subtleness: + in a URL
>> means a
>> >> space character, it has to be escaped as %2B. Particularly a
>> problem in
>> >> gmail message-ids.
> the link in question works just fine without escaping the +; the + only
> has to be escaped in then query component of a URL, not in the path
> component where it is just another valid character - and the link in
> question did not contain any query component.
> (see RFC 3986 sections 3.3 and 3.4)

Well, the backend does unescape, so regardless of what is legal by URL
syntax, the current implementation and therefore existing link tags
expect it to be escaped (this is a consequence of the bouncer turning
the link into a query URL in a redirect.) So they will need to be
escaped no matter what RFC 3986 says. Consider a part of the
specification for links.

That being said, we could definitely choose to interpret + as a + rather
than space. I don't know if we can easily distinguish between "%20",
"+" and " ", though, without dramatically change the implementation.

>> A quoted Message-ID might be weird as heck, but one rarely if ever see
>> them, I don't know if they are even legal.
> I don't think they are even possible, as the percent-sign is just another
> valid character in a Message-ID - but so is the '+' sign, so it seems
> you're trying to solve a non-existent problem...
> (see RFC 5322 section 3.2.3)

I'm referring to message-id's with a obs-id-left production.


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