[tor-bugs] #16824 [Tor]: coexistence of client and relay processing on same thread poses traffic confirmation risk

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#16824: coexistence of client and relay processing on same thread poses traffic
confirmation risk
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     Reporter:  starlight  |      Owner:
         Type:  defect     |     Status:  new
     Priority:  normal     |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor        |    Version:  Tor: 0.2.6.10
   Resolution:             |   Keywords:
Actual Points:             |  Parent ID:
       Points:             |
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Comment (by starlight):

 Indeed, a separate client-worker thread that passes
 cells to and from the relay worker thread appears an
 ideal solution.  My other recommendations are premised
 on the assumption that this would require significant
 work and mitigating confirmation-analysis exposure for
 users in the near term is important.

 If the above is implemented, a warning should be
 logged if fewer than two physical processors are
 available to the tor process since running both
 client and relay threads on a single core would
 cause client activity to impact relay forwarding.
 Two real physical cores should be the minimum,
 as two SMT threads (aka Hyperthreads) on a single
 physical core would not truly isolate the relay
 and client.

 During implementation, some attention should be
 paid as to whether the client/relay interaction
 is in any way detectible through statistical
 analysis of aggregate relay traffic.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16824#comment:4>
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