[tor-bugs] #18963 [Core Tor/Tor]: Download authority certificates even under blackholed authorities or fallbacks

[Tor Bug Tracker & Wiki]

#18963: Download authority certificates even under blackholed authorities or
fallbacks
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:
     Type:  defect                               |         Status:
 Priority:  Medium                               |  needs_review
Component:  Core Tor/Tor                         |      Milestone:  Tor:
 Severity:  Normal                               |  0.2.8.x-final
 Keywords:  must-fix-before-028-rc,              |        Version:  Tor:
  029-proposed                                   |  0.2.8.1-alpha
Parent ID:  #18816                               |     Resolution:
 Reviewer:                                       |  Actual Points:
                                                 |         Points:  small
                                                 |        Sponsor:
-------------------------------------------------+-------------------------
Changes (by teor):

 * keywords:  029-proposed => must-fix-before-028-rc, 029-proposed
 * status:  needs_revision => needs_review
 * points:  medium => small
 * parent:   => #18816
 * milestone:  Tor: 0.2.??? => Tor: 0.2.8.x-final


Comment:

 Please see my branch bug18963-remember on
 ​https://github.com/teor2345/tor.git for a much better fix. It remembers
 the directory we downloaded the consensus or certificates from, and re-
 uses it to download future certificates.

 06d05cb Fetch certificates from the same directory as the consensus
 ff122a2 Fetch certificates from the same directory as previous
 certificates
 (Optional, but I think it's a good idea.)

 This works well if multiple fallbacks or authorities are blackholed,
 because we've already found one that isn't.

 This might have minor security implications, if we fetch the consensus and
 its certificates from the same directory, it can feed us a consistently
 wrong view of the world.

 It's quite a simple code change (much of it it comments or argument-
 passing), I'd like to see it go in 0.2.8, so we achieve the goal of the
 fallback directory feature.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18963#comment:2>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online