Re: [xmpp] WGLC of draft-ietf-xmpp-posh-02

[Philipp Hancke <[e-mail]>]

Am 14.10.2014 01:17, schrieb Ben Campbell:
> (Oops, messed up the authors' address the first time. Apologies for the duplicate.)
>
> This is a Working Group Last Call of draft-ietf-xmpp-posh-02. The draft is available at the following URL:
>
> http://tools.ietf.org/html/draft-ietf-xmpp-posh-02
>
> The WGLC will conclude on 27 October, 2014. Please send your comments to the authors and the XMPP mailing list.

In several places, "Server identity" and "TLS client" are used, e.g.
 > Server identity checking (see [RFC6125]) involves three different
 > aspects:
[...]
 > a TLS client SHOULD consider the delegation invalid.

I think this is not the "TLS client" but the "POSH client" and the "Peer 
Identity". The main use case is when an xmpp s2s-server uses POSH to 
verify an incoming connection.

section 5:
	The TLS client SHOULD perform all POSH retrievals
	before opening any socket connections to the application
	protocol server.
(ed: extra whitespace before that sentence)

SHOULD is too strong here. I see it as a fallback rather and would only 
do POSH when not finding a proper identity. This would mean that 
sometimes, POSH is used without need.
I suspect this makes it easier to use POSH as part of the TLS handshake 
rather than as an application layer check.

This is also not possible for the s2s scenario where POSH may be 
triggered by an incoming
<db:result>somekeywhichwouldnotbeused</db:result>
which would happen after <starttls/> and after the TLS handshake itself 
is done.

Should be easy to fix though.