[tor-bugs] #6743 [Tor Client]: Don't set begindir_cutoff so low

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#6743: Don't set begindir_cutoff so low
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 Reporter:  arma        |          Owner:                    
     Type:  defect      |         Status:  new               
 Priority:  normal      |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Client  |        Version:                    
 Keywords:              |         Parent:  #3443             
   Points:              |   Actualpoints:                    
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 In #3443 we have problems where clients compute a low cbt, then end up
 giving up on a circuit while it's doing TLS handshakes, marking the relay
 down. This situation is especially bad when clients use bridges, since
 they give up on their bridges and then just sit there unwilling to connect
 to anything.

 It is too late to do complex changes for 0.2.3. I wonder if it's not too
 late for some simple fixes though.

 In particular, I'm thinking to let one-hop circuits use the full timeout,
 not half of it -- since the "half" heuristic makes even less sense when
 much of the circuit-building time is spent in the tls handshake.
 {{{
 -  SET_CUTOFF(begindir_cutoff, circ_times.timeout_ms / 2.0);
 +  SET_CUTOFF(begindir_cutoff, circ_times.timeout_ms);
 }}}

 In #3443, Mike suggested that we just disable cbt for begindir requests.
 That sounds fine in theory too, but I think that's more something I'd want
 to test in 0.2.4 for a bit.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6743>
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