[tor-bugs] #2732 [Tor Hidden Services]: Simplify hid_serv_responsible_for_desc_id

[Tor Bug Tracker & Wiki]

#2732: Simplify hid_serv_responsible_for_desc_id
---------------------------------+------------------------------------------
 Reporter:  rransom              |          Owner:  rransom           
     Type:  defect               |         Status:  needs_review      
 Priority:  major                |      Milestone:  Tor: 0.2.2.x-final
Component:  Tor Hidden Services  |        Version:                    
 Keywords:                       |         Parent:                    
   Points:                       |   Actualpoints:                    
---------------------------------+------------------------------------------

Comment(by rransom):

 Replying to [comment:7 nickm]:
 > I'm not sure this is the behavior we want; I think the old thing might
 be deliberate but broken.
 >
 > I think that the intention might have been for us to store the
 descriptor not only if we are listed as an HSDir at the right place in the
 consensus, but also if we are not an HSDir but we *are* listed in the
 right place in the consensus.  This is broken since the check for
 hid_serv_acting_as_directory() depends on the HSDir flag.

 `hid_serv_acting_as_directory` has always checked whether the relay is
 marked with the HSDir flag in the consensus, and
 `hid_serv_responsible_for_desc_id` has always called
 `hid_serv_acting_as_directory`.

 However, before
 [https://gitweb.torproject.org/tor.git/commitdiff/bf2717ff3d02e1c8527d6e6c8f14349813ba0e72
 commit bf2717ff], `hid_serv_responsible_for_desc_id` determined whether a
 relay is responsible for a given descriptor ID in a different way.  The
 prior method would have broken if less than
 `REND_NUMBER_OF_CONSECUTIVE_REPLICAS` relays had the HSDir flag (although
 those versions would have not attempted to look up HS descriptors at all
 in that case), but seems to be equivalent in other cases.

 > So I'd like to make sure that the intent *isn't* for non-HSDir routers
 to store descriptors anyway before we merge this.

 It looks like the intent was for non-HSDir routers to not store
 descriptors, but that's probably a bad design.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/2732#comment:8>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online