[tor-bugs] #16585 [Tor]: relay stops forwarding all traffic when client function cannot establish circuits -- scheduler_run() starvation

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#16585: relay stops forwarding all traffic when client function cannot establish
circuits -- scheduler_run() starvation
---------------------------+---------------------------
     Reporter:  starlight  |      Owner:
         Type:  defect     |     Status:  new
     Priority:  major      |  Milestone:
    Component:  Tor        |    Version:  Tor: 0.2.6.10
   Resolution:             |   Keywords:
Actual Points:             |  Parent ID:
       Points:             |
---------------------------+---------------------------

Comment (by starlight):

 This flaw is bad for anonymity!

 An adversary in a position to analyze the traffic
 of a relay that also operates as a client can
 easily identify outbound cells that are part of
 a new circuit establishment.  Those cells are
 written after a pause in general traffic
 forwarding and immediately ahead of the
 resumption of forwarding.  Is clear from
 the debug trace that the only cells written
 during circuit construction are related to
 the new circuit, while forwarding traffic is
 held suspended on queues.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16585#comment:10>
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