posting hidden service descriptors

[James Muir]

I am trying to sort out a few low-level details about hidden services.

I know that hidden servers must post their descriptors to the DAs 
anonymously to avoid exposing their IP addresses.  Is this done through 
a normal (i.e. three hop) circuit?  I suspect it is not because in 
src/or/circuitbuild.c there is a condition for creating one-hop tunnels 
and a log message "Launching a one-hop circuit for dir tunnel."

My concern here is that using a one-hop circuit exposes the origin of 
the hidden service to that onion router (i.e. the one-hop).  Even if the 
data the one-hop relays to the DA from the OP is encrypted, the one-hop 
still learns an IP address which originates some hidden service 
(although, it may not be certain which one exactly).

-James