[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:  tbb-
     Type:  defect                               |  team
 Priority:  Medium                               |         Status:
Component:  Tor Browser                          |  needs_review
 Severity:  Normal                               |      Milestone:
 Keywords:  tbb-torbutton tbb-circuit-display    |        Version:
  TorBrowserTeam201601R, tbb-5.5                 |     Resolution:
Parent ID:                                       |  Actual Points:
  Sponsor:                                       |         Points:
-------------------------------------------------+-------------------------
Changes (by arthuredelstein):

 * keywords:  tbb-torbutton tbb-circuit-display TorBrowserTeam201601 tbb-5.5
     => tbb-torbutton tbb-circuit-display TorBrowserTeam201601R, tbb-5.5
 * status:  assigned => needs_review


Comment:

 Replying to [comment:11 gk]:
 > Replying to [comment:10 gk]:
 > > Replying to [comment:9 cypherpunks]:
 > > > This problem is still present in 5.0.6. GNU/Linux, x64, English
 locale.
 > >
 > > How do I reproduce your issue?
 >
 > Okay, I found a way to reproduce at least one issue:
 >
 > 1) Open a new tab and go to https://bugzilla.mozilla.org/ (after it
 loaded the circuit should be visible)
 > 2) Choose Search -> Advanced Search
 > 3) Click on Detailed Bug Information and enter `[tor]` in the Whiteboard
 row
 > 4) Click on Search and after you got your results checking the circuit
 display does not show any curcuit anymore
 >
 > Reloading does not help either. I am not sure if this is caused by our
 fixup done in this bug yet or whether that is an additional issue we
 overlooked so far.

 I found that browsing to the URL
 https://bugzilla.mozilla.org/buglist.cgi?a
 reproduces the error.

 For each loaded document, the tor circuit display looks up the SOCKS user
 name and password. Normally it calls `getSOCKSCredentials(browser)` which
 does the equivalent of:
 {{{
 currentDocumentChannel.QueryInterface(Ci.nsIProxiedChannel).proxyInfo
 }}}
 It turns out that that the offending URL causes an nsIMultiPartChannel
 instead of an nsIHttpChannel to be associated with the document, so that
 `currentDocumentChannel.QueryInterface(Ci.nsIProxiedChannel)` fails.

 But the main nsIHttpChannel can be found at
 nsIMultiPartChannel.baseChannel. So in that situation we need to use
 something like
 {{{
 currentDocumentChannel.QueryInterface(Ci.nsIMultiPartChannel).baseChannel.QueryInterface(Ci.nsIProxiedChannel).proxyInfo
 }}}

 Here's a patch to do this:
 https://github.com/arthuredelstein/torbutton/commit/16990+1

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16990#comment:13>
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