[tor-bugs] #7341 [Tor]: circuit_expire_building applies CBT in twisted ways on hidden service circuits

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#7341: circuit_expire_building applies CBT in twisted ways on hidden service
circuits
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 Reporter:  mikeperry   |          Owner:                    
     Type:  defect      |         Status:  new               
 Priority:  normal      |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor         |        Version:                    
 Keywords:  tor-client  |         Parent:                    
   Points:              |   Actualpoints:                    
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Comment(by rransom):

 Replying to [comment:9 mikeperry]:
 > Replying to [comment:7 rransom]:
 > > Replying to [comment:6 mikeperry]:
 > > > Some notes of interest from the event logs rransom suggested:
 > > >
 > > > 1. The cannibalization situation is even worse than the
 inappropriate short-timeout application I noted above. If a circuit is
 cannibalized, we never update the creation timer. This means that if a
 circuit lies idle for any amount of time, it will instantly time out when
 it is cannibalized.
 > >
 > >
 [https://gitweb.torproject.org/tor.git/blob/tor-0.2.4.6-alpha:/src/or/circuituse.c#l1328
 No.]
 >
 > What about rend_client_reextend_intro_circuit()? It appears to call
 circuit_extend_to_new_exit() without a path to
 circuit_launch_by_extend_info() or a timestamp update.

 Good point, but the problem there is that
 `rend_client_reextend_intro_circuit` is only re-extending the circuit, not
 cannibalizing it properly.  The ‘actually cannibalize circuit foo for
 purpose bar’ code should be split out of `circuit_launch_by_extend_info`
 into a separate function.  (Open a separate ticket for this change.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/7341#comment:10>
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