[tor-bugs] #28942 [Circumvention/Snowflake]: Evaluate pion WebRTC

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#28942: Evaluate pion WebRTC
--------------------------------------------+------------------------------
 Reporter:  backkem                         |          Owner:  cohosh
     Type:  enhancement                     |         Status:  accepted
 Priority:  Medium                          |      Milestone:
Component:  Circumvention/Snowflake         |        Version:
 Severity:  Normal                          |     Resolution:
 Keywords:  anti-censorship-roadmap-august  |  Actual Points:
Parent ID:                                  |         Points:  5
 Reviewer:                                  |        Sponsor:
                                            |  Sponsor28-must
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Comment (by dcf):

 Replying to [comment:57 dcf]:
 > Replying to [comment:54 cohosh]:
 > > In addition to the issues above, which can be solved with the attached
 patch
 >
 > I've started a build using the patch. The exact commit I'm building from
 is [https://gitweb.torproject.org/user/dcf/tor-browser-build.git/log/?h
 =pion-webrtc&id=f52281ae5bca107414a5292e74e2f1eca0608a3b
 f52281ae5bca107414a5292e74e2f1eca0608a3b]. Specifically, it makes the
 following changes relative to comment:51:
 >  * Applied attachment:0001-Allow-gathering-of-candidates-to-generate-
 offer.patch.
 >  * Picked up your
 [https://github.com/cohosh/snowflake/commit/e5040c70f9a4d8e47ed9e37b2f0c944859a9c56c
 "Make sure command line ice servers are used"] commit.
 >  * It does ''not'' pick up the
 [https://github.com/cohosh/snowflake/commit/ee8ddfe579092a126434bae4cf83203caf1d818b
 "Connect pion library logger with snowflake log"] commit from comment:56.
 I wasn't clear on whether that commit fixes something or whether it
 introduces its own race condition.

 Here is the build. It's working!

  * [https://gitweb.torproject.org/user/dcf/tor-browser-build.git/log/?h
 =pion-webrtc&id=f52281ae5bca107414a5292e74e2f1eca0608a3b
 f52281ae5bca107414a5292e74e2f1eca0608a3b pion-webrtc] branch
  * https://people.torproject.org/~dcf/pt-bundle/tor-browser-pion-
 webrtc-20190905-f52281ae5/

 I tested the linux and windows builds, and also tried extracting
 snowflake-client and running it headless on a server. There are still user
 experience problems, but I think this is the first time we've had a rbm-
 build Tor Browser bootstrapping on Windows.

  * Bootstrapping on Windows took a long time, about 10 minutes. I tried
 again, after deleting the installation directory to remove the consensus
 cache, and it took about 7 minutes.
  * I'm having trouble actually loading a web page after bootstrapping,
 though it does notice that a 9.05a update is available and presumably
 starts downloading it. I only got it to load example.com once. This may be
 caused by a slow proxy, or #25429 or something. I see a lot of `[NOTICE]
 We tried for 15 seconds to connect to '[scrubbed]'...` in the logs. We
 could try a larger `CircuitBuildTimeout`.

 I went back and checked to see if perhaps pion-webrtc v2.0.23 from
 comment:49 had really been working all along, and I just failed to test it
 properly. I extracted its snowflake-client again and tried bootstrapping
 about a dozen times, and twice it got to 25% then failed, the other times
 it was as in comment:49. So I don't know what to make of that. Maybe it
 happened to get lucky and hit a proxy-go instance those two times, which
 would be consistent with the observation in comment:50.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28942#comment:59>
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