Re: [rtcweb] ALPN question - other labels?

[Martin Thomson <[e-mail]>]

On 7 August 2014 14:24, Paul Kyzivat <[e-mail]> wrote:
>    Only one of these labels can be used for any given session.  A peer
>    acting in the client role MUST NOT offer both identifiers.  A peer in
>    the server role that receives a ClientHello containing both labels
>    MUST reject the session, though it MAY accept the confidential option
>    and protect content accordingly.
>
> This does not quite say that a peer in a server role must reject a session
> that contains some *other* label. It doesn't even explicitly forbid a peer
> in a client role from offering some other label. Does it intend to do so?

That's actually old, incorrect text.  I need to update the draft, but
don't want to do every time that I make a change (I'm not looking to
top Ian Hickson's record here).

Here's what my copy says:

"""A peer that is not aware of whether it needs to request
confidentiality can use either form. A peer in the client role MUST
offer both identifiers if it is not aware of a need for
confidentiality. A peer in the server role SHOULD select webrtc if it
does not prefer either.""
-- https://martinthomson.github.io/drafts/draft-ietf-rtcweb-alpn.html#rfc.section.2

As to whether a completely different protocol is acceptable, the
intent was to only cover the interaction of the two labels that are
defined in the document.  If you want to do webrtc OR some other
protocol, I see no reason not to permit that.