OIDC and dynamic ports on the metadata redirect_uris?

[Bryan K. Walton]

We are working to implement Dovecot Oauth authentication using our
Shibboleth IdP.  In my early testing, I'm working with the Mutt email
client and their mutt_oauth2.py script. That script uses a temporary
port on the loopback interface during code generation and the port 
changes every time, as it looks for an unused port when it is being run
and it can't know that a hard-coded port is always going to be available 
on various workstations.

I've been trying to find a way in our OIDC metadata on the IdP to
specify a wildcard for the port.  Our redirect_uris field is using
the loopback interface, http://127.0.0.1.  
According to RFC 8252 (section 7.3):

"The authorization server MUST allow any port to be specified at the
   time of the request for loopback IP redirect URIs, to accommodate
   clients that obtain an available ephemeral port from the operating
   system at the time of the request."

Source: https://datatracker.ietf.org/doc/html/rfc8252#section-7.3

Does the Shibboleth IdP support this feature?  If so, what should I be
using for the port wildcard in the metadata?

Thanks!
Bryan Walton

-- 
Bryan K. Walton						  319-337-3877 
Senior Linux Systems Administrator	    Leepfrog Technologies, Inc