[tor-bugs] #4483 [Tor Client]: If k of n authorities are down, k/n bootstrapping clients are delayed for minutes

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#4483: If k of n authorities are down, k/n bootstrapping clients are delayed for
minutes
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 Reporter:  arma                                  |          Owner:                    
     Type:  defect                                |         Status:  new               
 Priority:  normal                                |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor Client                            |        Version:                    
 Keywords:  performance bootstrap dos-resistence  |         Parent:  #2664             
   Points:                                        |   Actualpoints:                    
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Comment(by mikeperry):

 Hrmm.. In order to support parallel consensus downloads, we probably need
 HTTP 1.1 range requests, which don't seem to be supported by the dirauths
 (who only implement HTTP 1.0).

 How about this then: Bootstrapping clients make T concurrent test
 connections to a random selection of the N dirauths and M directory
 mirrors from #572. When the first connection succeeds, they close the
 remaining T-1 test connections, download the consensus through it, and
 then close it. No timeout changes, and we solve the "k nodes are down"
 bootstrap problem.

 We should also ensure that in all cases, some fixed fraction of the T test
 connections go to the M directory mirrors, because the whole reason this
 issue is important is because we want to the ability to enter into a
 "panic mode" if the dirauths are under a resource exhaustion attack or
 other DoS condition (such as the dirauth crash in the description of
 #2664).

 Does this need a proposal to clarify and debate, or is this plan good
 enough to begin work on?

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4483#comment:5>
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