[tor-bugs] #25347 [Core Tor/Tor]: Tor stops building circuits, and doesn't start when it has enough directory information

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#25347: Tor stops building circuits, and doesn't start when it has enough directory
information
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  asn
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.0.6
 Severity:  Normal                               |     Resolution:
 Keywords:  031-backport, 032-backport,          |  Actual Points:
  033-must, tor-guard, tor-client, tbb-          |
  usability-website, tbb-needs,                  |
  033-triage-20180320, 033-included-20180320     |
Parent ID:  #21969                               |         Points:  1
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by mikeperry):

 A couple comments here:

 1. We already treat non-destroy failures at the guard as rotate-away
 failures in circuit_build_failed(). Note that there is an explicit check
 to not blame the guard if circ->base_.received_destroy is set. If we
 remove that check in circuit_build_failed(), we should not need asn's
 patch, as the behavior would then be equivalent (or actually a superset,
 since it would cover all destroy reasons). (I think this is what arma
 meant in his point H?). This would be a simpler patch.

 2. Roger's point G is scary. I like the solution in E, though, and I think
 it actually fixes G. If predicted circuits set an is_predicted flag in
 circuit_predict_and_launch_new(), and then we check that flag in
 select_entry_guard_for_circuit() to completely ignore the is_reachable
 status there, then predicted circuits should periodically cause
 entry_guards_node_success() to get called upon any success of a predicted
 circuit for spuriously failing guards, so they don't go the whole 30
 minutes without being used again. I am a fan of this plan, and could write
 a patch for it if we like it.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25347#comment:25>
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