control port protocol notifications for hidden service availability
Currently, there is no facility provided by tor that tells us when our Tor hidden service is accessible after it has been created. I would like this information regardless if the Tor hidden service was created via a torrc or control port... or if easier to implement this could be a specific feature addition to ephemeral hidden services described in Tor trac ticket #6411 (moved) https://trac.torproject.org/projects/tor/ticket/6411
I am working on various Tor hidden service applications that could definitely use this feature... most notably txtorcon tor hidden service endpoints can fire their Twisted listen deferreds when the hidden service is available. In this case we'd want an asynchronous event with that message.
In the context of the Tahoe-LAFS native Tor integration (https://tahoe-lafs.org/trac/tahoe-lafs/ticket/517 AND http://foolscap.lothar.com/trac/ticket/203) we can imagine a situation where a storage service creates a txtorcon tor hidden service endpoint and calls it's listen() method. It would be optimal for this storage server to not announce it's onion address until it was actually accessible... that is until after the HS descriptor has been disseminated sufficiently to guarantee transport.