Add more fields when disclosing publisher or caller

[martin31821]

This further improves the compatibility to crossbar.io by disclosing
caller_authid, caller_authrole, caller_authmethod and caller_authextra if set.

For pubsub, the same properties are exposed.

[gammazero]

Thank you for this. However, I must request that only authid and authrole are supported.

The WAMP standardization group has reached the consensus that the supported fields will be authid and authrole. The discussion of this feature is here: wamp-proto/wamp-proto#57

Some background (from discussion): On the subject fo including these fields with publisher and caller identification, according to Tobias Oberstein (Crossbar.IO):

Crossbar.io had implemented that in the past. And we removed it again. The reason: the next thing after authid/authrole asked for was transport level details: "we need access to the WebSocket cookie in callees". CB has more information about the Caller than just session ID, authid and authrole. Where do we stop? It doesn't make sense to transmit all that information in each and every call.

Also from Oberstein:

This is how it is implemented in Crossbar.io now:

Both publisher and caller disclosure can be enabled on a per URI basis in the router configuration
The detail attributes in EVENT messages are: publisher (the WAMP session ID of the publisher), >publisher_authid and publisher_authrole
The detail attributes in the INVOCATION messages are: caller (the WAMP session ID of the caller), caller_authid and caller_authrole
I do think this reflects the end result of our discussion of the feature. @mbonneau does it?

It isn't reflected in the specification though. And eg Thruway uses different attribute names

Related issue with autobahn-js: crossbario/autobahn-js#219
and with Thruway: voryx/Thruway#206

If we want to include additional fields, these should be optional to enable, default disabled, and the non-standard field names should begin with x_nx_ I would not want to do that as part of this PR, if at all. Implementations that include additional fields are already updated or going to be updated to only include those fields as x_... custom fields.

Conclusion: Nexus needs to include authid and authrole, for publisher and caller identification, even though this is not yet in the WAMP spec. It should not include additional fields as those will not be in compliance with WAMP-protocol.

[gammazero]

Only features needed are "authid" and "authrole". See PR discussion.

[gammazero]

Only features needed are "authid" and "authrole". See PR discussion.

[gammazero]

This looks good. I am going to hold off merging for a day or two until I get some feedback from WAMP standards group on whether they want publisher_authid or just authid, and same for other fields.