[tor-bugs] #19001 [Obfuscation/Snowflake]: Tor Browser with Snowflake

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#19001: Tor Browser with Snowflake
-----------------------------------+---------------------
 Reporter:  dcf                    |          Owner:
     Type:  project                |         Status:  new
 Priority:  Medium                 |      Milestone:
Component:  Obfuscation/Snowflake  |        Version:
 Severity:  Normal                 |     Resolution:
 Keywords:                         |  Actual Points:
Parent ID:                         |         Points:
 Reviewer:                         |        Sponsor:
-----------------------------------+---------------------

Comment (by dcf):

 First working bundles with Snowflake, for linux only:
  * https://people.torproject.org/~dcf/pt-
 bundle/snowflake-20160509-5a801bf207/
  * https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/log/?h=snowflake&id=5a801bf2077e55c7b0dc35faed101a6c3d5375fb
 Overall diff so far:
  * https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/diff/?h=snowflake&id=5a801bf2077e55c7b0dc35faed101a6c3d5375fb&id2=a00e9b4617c65e8a09eb7584ebe92aa76df24ec3

 To run,
  1. Open another browser to
 http://keroserene.net/snowflake/snowflake.html.
  2. Run ./start-tor-browser.desktop
  3. Say yes to "Does your Internet Service Provider (ISP) block or
 otherwise censor connections to the Tor Network?" and select snowflake
 from the menu.
 If all goes well, after a few seconds the other browser should turn green.

 In order to build it yourself, you have to do
 {{{
 git clone -b snowflake https://git.torproject.org/user/dcf/tor-browser-
 bundle.git
 cd tor-browser-bundle/gitian
 build nightly TORSOCKS=
 }}}
 You'll need to prepared the gitian-builder directory and everything else
 according to [[doc/TorBrowser/Hacking]] and
 [[doc/TorBrowser/BuildingWithGitian]]. I did not try targets other than
 nightly.

 Explanations of some noteworthy changes:
  * I cherry-picked [[attachment:0001-Upgrade-go-
 to-1.6.2.patch:ticket:18333|the Go 1.6 patch]] from #18333 because arlolra
 said there is a dependency on Go 1.5 having to do with SRCDIR.
  * I [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/fetch-
 inputs.sh?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n308
 tried using] `--no-history` when running depot_tools' `fetch` and
 `gclient`, but it doesn't seem to work because the directories are 12 GB
 and have history.
  * libwebrtc needs a newer GCC than Debian wheezy has, so
 [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/descriptors/linux/gitian-pluggable-
 transports.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n104
 I copied code] from the [https://gitweb.torproject.org/user/dcf/tor-
 browser-bundle.git/tree/gitian/descriptors/linux/gitian-
 firefox.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n57
 firefox descriptor] to use our self-built GCC. I also tried building
 libwebrtc with Clang, which worked, but I couldn't get the resulting
 library to link with go-webrtc and Cgo.
  * At https://github.com/keroserene/go-webrtc/issues/23#issue-123390551,
 serene said that it was necessary to create a custom ninja file, but I
 didn't find it necessary (nor did I know what to put in the custom file).
  * [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/descriptors/linux/gitian-pluggable-
 transports.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n327
 The GYP_DEFINES] are a result of trial and error and cribbing from the
 Debian [https://packages.debian.org/jessie/chromium chromium-browser]
 source package.
  * I [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/descriptors/linux/gitian-pluggable-
 transports.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n329
 had to install Java and set JAVA_HOME] to get past what seems to be a
 trivial step in webrtc/build/gyp_webrtc.
  * For constructing libwebrtc-magic.a,
 [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/descriptors/linux/gitian-pluggable-
 transports.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n332
 I used] the `ar crs` command from [https://github.com/keroserene/go-
 webrtc/blob/3a7f6aed75357dc85a7438af10b12c4177cf180f/build.sh#L68-L69 go-
 webrtc's build.sh], but I had to exclude an additional file,
 dump_syms_regtest.o.
  * I [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/descriptors/linux/gitian-pluggable-
 transports.yml?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n354
 had to disable] `_GLIBCXX_USE_CXX11_ABI=0` when building go-webrtc,
 because the prebuilt libwebrtc-magic.a is built an older default
 `_GLIBCXX_USE_CXX11_ABI=0`, but the Gitian-built libwebrtc-magic.a is
 built with the new default which is `_GLIBCXX_USE_CXX11_ABI=1`.
  * I [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/commit/?h=snowflake&id=f2a142866932528549b525b0e31f8ecdb3a50a71
 used an old version] of snowflake, [https://gitweb.torproject.org
 /pluggable-
 transports/snowflake.git/log/?id=598e2a3bfb1cd8effab4c1b945035c870be16bff
 598e2a3bfb1cd8effab4c1b945035c870be16bff], because that's the parent of
 the bad commit mentioned in #18653. It might not be the same problem, but
 I couldn't get snowflake master to bootstrap past 10%.
  * I [https://gitweb.torproject.org/user/dcf/tor-browser-
 bundle.git/tree/gitian/verify-
 tags.sh?h=snowflake&id=235bdbc03d29e9e84e22f9fa6212677179293bc0#n159
 didn't know what to do about webrtc] in verify-tags.sh, since the `gclient
 sync` step clones a bunch of other repos within itself.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19001#comment:1>
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