[tor-bugs] #2317 [Tor Client]: Missing sanity checks for cbtnummodes consensus parameter

Tor Bug Tracker & Wiki torproject-admin at torproject.org
Wed Jan 12 20:49:52 UTC 2011


#2317: Missing sanity checks for cbtnummodes consensus parameter
------------------------+---------------------------------------------------
 Reporter:  Sebastian   |       Owner:                    
     Type:  defect      |      Status:  needs_review      
 Priority:  major       |   Milestone:  Tor: 0.2.2.x-final
Component:  Tor Client  |     Version:                    
 Keywords:              |      Parent:                    
------------------------+---------------------------------------------------

Comment(by arma):

 {{{
          research indicates that a lower value would mean fewer cells in
          transit in the network at any given time. Obeyed by Tor 0.2.1.20
          and later.
 +        Min: 1, Max: 100000 XXX are these sane
 }}}

 If an exit relay sets its circ package window higher than 1000, it will
 cause current Tor clients that use it to close those circuits because it
 will violate their deliver_window >= 0 checks.

 But if we later change Tor clients to handle that better (e.g. to read the
 circwindow out of the consensus and assume that exit relays are using that
 value), then we wouldn't want to have put a constraint in.

 Also, if the circ package window is 1, current Tor clients will fail to
 use that circuit well, because they won't send any sendmes back until
 they've gotten 100 cells. So we could argue for a minimum of 100. But at
 the same time, I don't want to dictate to future clients what their
 constraints should be, in case we change the sendme design in the future.

 So why not [0, MAX_INT32] here?

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/2317#comment:21>
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