[tor-bugs] #23863 [Core Tor/Tor]: When our directory guards don't have each others' microdescs, we should mark some dead

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#23863: When our directory guards don't have each others' microdescs, we should
mark some dead
-----------------------------------------------+---------------------------
 Reporter:  teor                               |          Owner:  (none)
     Type:  defect                             |         Status:  new
 Priority:  Medium                             |      Milestone:  Tor:
                                               |  0.3.2.x-final
Component:  Core Tor/Tor                       |        Version:  Tor:
                                               |  0.3.0.6
 Severity:  Normal                             |     Resolution:
 Keywords:  tor-guard, tor-bridge, tor-client  |  Actual Points:
Parent ID:  #21969                             |         Points:  1
 Reviewer:                                     |        Sponsor:
-----------------------------------------------+---------------------------

Comment (by asn):

 Replying to [comment:1 teor]:
 > Here's what we could do:
 > 1. Try some directory mirrors
 > 2. Try a fallback
 > 3. Try an authority
 > 4. If we still don't have mds for one or more primary guards, mark them
 dead until the next consensus
 >
 > This deals with the scenario where:
 > 1. Authorities make new consensus with new mds (hh:00)
 > 2. Client bootstraps and downloads consensus from authorities (either at
 random because they are part of the fallback list, or due to options)
 > 3. Client chooses directory guards
 > 4. Client tries directory guards for new mds
 > 5. Directory guards are waiting for a random time between hh:00 and
 hh:30 to fetch new consensus and new mds. See
 https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n3240

 Seems to me that the ways to deal with the edge case you describe above
 are:

 a) Eventually clients try authorities to fetch mds if all else fails (bad
 for the health of dirauths). I think that's what you suggested basically.

 b) We remove dirauths from the fallback list (any drawback?)

 c) We make dirservers fetch new consensuses/mds much faster than 30mins
 delay (bad for health of dirauths).

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23863#comment:2>
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