[tor-bugs] #20539 [Core Tor/Tor]: Make sure fallback directories aren't running buggy versions / can deliver a recent consensus

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#20539: Make sure fallback directories aren't running buggy versions / can deliver
a recent consensus
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 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: 0.2.9.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  fallback      |  Actual Points:
Parent ID:  #18828        |         Points:  0.5
 Reviewer:                |        Sponsor:
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Comment (by teor):

 Bug #20499 affects versions from 0.2.9.1-alpha-dev to 0.2.9.4-alpha-dev
 and version 0.3.0.0-alpha-dev, so we need to exclude these versions as
 fallbacks. We can't rely on the authorities to do this, as #20509 has not
 been deployed to directory authorities yet.

 We should also exclude authorities that can't deliver a recent microdesc
 consensus, based on the script in #20501. We already download a consensus
 from every authority to check download times. If we download a miscrodesc
 consensus, that's what clients will be downloading. And it's slightly
 faster.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20539#comment:7>
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