[tor-bugs] #23862 [Core Tor/Tor]: Tor only updates guard state after a consensus if it has enough directory info

[Tor Bug Tracker & Wiki]

#23862: Tor only updates guard state after a consensus if it has enough directory
info
-------------------------+-------------------------------------------------
     Reporter:  teor     |      Owner:  (none)
         Type:  defect   |     Status:  new
     Priority:  Medium   |  Milestone:  Tor: 0.3.2.x-final
    Component:  Core     |    Version:  Tor: 0.3.0.6
  Tor/Tor                |   Keywords:  tor-guard, tor-bridge, tor-client,
     Severity:  Normal   |  030-backport, 031-backport
Actual Points:           |  Parent ID:  #21969
       Points:  1        |   Reviewer:
      Sponsor:           |
-------------------------+-------------------------------------------------
 Steps to reproduce:
 1. Launch tor in a fresh data directory
 {{{
 export DATADIR=`mktemp -d`
 src/or/tor DataDirectory "$DATADIR" StrictNodes 1 EntryNodes
 1390DFDB5603AB5A16564505D7AE8647B1818A3C
 }}}
 2. Delete its microdescriptors
 {{{
 rm -v "$DATADIR"/cached-microdescs*
 }}}
 3. Repeat step 1

 Expected behaviour:

 Tor uses the selected EntryNode

 Actual Behaviour:

 Tor uses a fallback directory mirror

 This happens because tor should update guard state after every consensus,
 but it only updates guard state when it has enough directory info.

 It is pathological when combined with #23817, when tor gets in a state
 when it doesn't have enough directory info because its guards are broken,
 and never updates its guard state, so it can't get enough directory info.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23862>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online