[tor-bugs] #16990 [Tor Browser]: Circuit visualizer stops working after some time

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#16990: Circuit visualizer stops working after some time
-------------------------------------------------+-------------------------
 Reporter:  cypherpunks                          |          Owner:
     Type:  defect                               |  arthuredelstein
 Priority:  Medium                               |         Status:
Component:  Tor Browser                          |  needs_review
 Severity:  Normal                               |      Milestone:
 Keywords:  tbb-torbutton, tbb-circuit-display,  |        Version:
  TorBrowserTeam201602R                          |     Resolution:
Parent ID:                                       |  Actual Points:
  Sponsor:                                       |         Points:
-------------------------------------------------+-------------------------

Comment (by cypherpunks):

 Replying to [comment:28 cypherpunks]:
 > {{{
 > +    // punk: bug: underflow if the callback triggers before the
 sendCommand()
 > +    // in the following Promise is called (and, therefore, a triple is
 pushed
 > +    // into "commandQueue")
 > +    //
 > +    // -> wait! apparently this is not actually an error (wat?):
 [].shift()
 > +    // just returns undefined
 > +    //
 > +    // -> but then the _assignment_ fails: throws TypeError
 > +    //
 > +    // -> this may be happening in the case of the circuit display
 fuck-up: the
 > +    // reply message is cut short, but the rest of the message (some
 circuit
 > +    // status lines and then '.' and then '250 OK') will still be
 delivered by
 > +    // Firefox through the socket, will be received by the smattering
 of
 > +    // chained funclets, and could then be made into a new message that
 will be
 > +    // passed into this function
 > }}}

 You were right.

 My display disappeared and I found this log
 {{{
 [02-14 12:23:18] Torbutton INFO: controlPort << getinfo circuit-status
 [02-14 12:23:18] Torbutton INFO: controlPort >> 250+circuit-status=
 248 BUILT [redacted]
 247 BUILT [redacted]
 249 BUILT [redacted]
 250 BUILT [redacted]
 [02-14 12:23:18] Torbutton INFO: controlPort >> 251 EXTENDED [redacted]
 [02-14 12:23:18] Torbutton WARN: TypeError: commandQueue.shift(...) is
 undefined
 [02-14 12:23:18] Torbutton WARN: Disabling tor display circuit because of
 an error.
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16990#comment:39>
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