[tor-bugs] #28205 [Obfuscation/Snowflake]: linking against other libwebrtc binaries errors out on missing symbols

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#28205: linking against other libwebrtc binaries errors out on missing symbols
-----------------------------------+------------------------------
 Reporter:  eighthave              |          Owner:  eighthave
     Type:  defect                 |         Status:  needs_review
 Priority:  Medium                 |      Milestone:
Component:  Obfuscation/Snowflake  |        Version:
 Severity:  Major                  |     Resolution:
 Keywords:  android                |  Actual Points:
Parent ID:                         |         Points:
 Reviewer:                         |        Sponsor:
-----------------------------------+------------------------------

Comment (by arlolra):

 Replying to [comment:44 eighthave]:
 > About the patch, could a more descriptive name be used instead of
 `package lib`?  I'm not sure the rules of Go namespaces, we will need to
 avoid name conflicts since ultimately, we want to bundle as many PTs
 together into a single shared library, which then can be dynamically
 loaded/started/stopped from tor daemon, Orbot, in Android apps, etc.

 See https://golang.org/ref/spec#Import_declarations

 In the top level `client/snowflake.go`, it's imported as,

 {{{
 sf "git.torproject.org/pluggable-transports/snowflake.git/client/lib"
 }}}

 and used like `sf.SnowflakeCollector`, etc.

 Replying to [comment:46 eighthave]:
 > Ok, I figured out the `go get` issue, it seems sometimes that `go get`
 decides that it needs to have `.git` at the end of the path, and other
 times not.  So I used symlinks to provide both options.  Then I only built
 `.../client/lib`, not the whole client.  `gomobile bind` gets pretty far
 before dying with:
 >
 > {{{
 > /tmp/gomobile-work-032904235/src/gobind/go_libmain.go:1052:17: cannot
 use (*proxylib_SocksConnector)(_param_socks_ref) (type
 *proxylib_SocksConnector) as type lib.SocksConnector in assignment:
 >       *proxylib_SocksConnector does not implement lib.SocksConnector
 (missing Grant method)
 > /tmp/gomobile-work-032904235/src/gobind/go_libmain.go:1061:22: cannot
 use (*proxylib_SnowflakeCollector)(_param_snowflakes_ref) (type
 *proxylib_SnowflakeCollector) as type lib.SnowflakeCollector in
 assignment:
 >       *proxylib_SnowflakeCollector does not implement
 lib.SnowflakeCollector (missing Melted method)
 > }}}
 > https://gitlab.com/eighthave/snowflake/-/jobs/123509344

 These are the same issues as before with unsupported export types.  What
 needs to be done is a `client/mobile/` that imports from `client/lib/` but
 only exposes a few methods that your app would need.  (On that note, since
 the problematic methods are now in `lib/` you can probably build the top
 level `client/` without issue, but that probably doesn't help when you
 want to integrate the functionality into your app.  It's just for show.)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28205#comment:48>
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