Re: [TLS] Accepting that other SNI name types will never work.

Dave Garrett <davemgarrett@gmail.com> Fri, 04 March 2016 01:43 UTC

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From: Dave Garrett <davemgarrett@gmail.com>
To: tls@ietf.org
Date: Thu, 3 Mar 2016 20:43:42 -0500
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Cc: Adam Langley <agl@imperialviolet.org>
Subject: Re: [TLS] Accepting that other SNI name types will never work.
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Do we want to stick some simple new constraints on SNI in the TLS 1.3 draft spec? e.g. SHOULD have exactly one host_name which SHOULD be less than N bytes (significantly less than the current theoretical 64kB ceiling). Just adding a quick blurb for this in there somewhere seems like the simplest solution to me.


Dave


On Thursday, March 03, 2016 06:16:25 pm Martin Thomson wrote:
> If we actually have a volunteer for sni-bis, then that would be OK with me.
> 
> However, I don't regard the errors as important.  Any hope that they
> might be used in some automated fashion died a long time ago.  Mainly
> due to this complete lack of consistency.  I assume that the last
> error indicates that you didn't get an alert, which I find is
> alarmingly common in TLS.
> 
> On 4 March 2016 at 09:52, Richard Moore <rich@kde.org> wrote:
> > If you're fixing that then maybe standardising the errors makes sense too.
> > My fingerprinter sees the following:
> >
> > For an empty name:
> >
> > SNIEmptyName: *(301)alert:DecodeError:fatal|
> > SNIEmptyName: *(301)alert:HandshakeFailure:fatal|
> > SNIEmptyName: *(301)alert:IllegalParameter:fatal|
> > SNIEmptyName: *(303)alert:UnexpectedMesage:fatal|
> > SNIEmptyName: error:Unexpected EOF receiving record header - server closed
> > connection|
> >
> > For a long name (x repeated 500 times):
> >
> > SNILongName: *(301)alert:HandshakeFailure:fatal|
> > SNILongName: *(301)alert:IllegalParameter:fatal|
> > SNILongName: *(301)alert:UnrecognizedName:fatal|
> > SNILongName: *(303)alert:UnexpectedMesage:fatal|
> > SNILongName: error:Unexpected EOF receiving record header - server closed
> > connection|
> >
> > Rich.
> >
> >
> > On 3 March 2016 at 22:44, Martin Thomson <martin.thomson@gmail.com> wrote:
> >>
> >> On 4 March 2016 at 05:49, Adam Langley <agl@imperialviolet.org> wrote:
> >> > (I think the lesson here is that protocols should have a single joint,
> >> > and that it should be kept well oiled. For TLS, that means that
> >> > extensions should have minimal extensionality in themselves and that
> >> > we should generally rely on the main extensions mechanism for these
> >> > sorts of things.)
> >>
> >> Big +1
> >>
> >> Note that the NSS bug also entailed non-zero SNI name types
> >> overwriting the actual SNI.