1432684 - add flag to drop screensharing from build

Status: NEW

(Firefox Build System :: General, enhancement)

Description

[Arthur Edelstein [:arthur]]

In Tor Browser, we have a patch to leave out screensharing code from our build to avoid any possibility of a proxy bypass. It would be ideal if we could introduce a mozconfig flag to do this, so we don't have to maintain a separate patch.

Here's our current patch:
https://torpat.ch/16439
and the original ticket:
https://trac.torproject.org/16439

Comment 1

[Gregory Szorc [:gps]]

This seems like a relatively trivial feature request. The big part missing from the patch is a feature flag in moz.configure. That would look something like the following, added to browser/moz.configure:

option('--disable-screensharing', help='...')

@depends('--disable-screensharing')
def screensharing(value):
    if value:
        return True

set_config('MOZ_SCREENSHARING', screensharing)

dolske: not sure who owns screensharing. The file history is pretty short and all but the initial commit by blassey is formatting changes. A build peer could get this patch landed easily enough. Do you have any problems with us doing that?

Comment 2

[Justin Dolske [:Dolske]]

I generally have no concerns about adding such flags when Tor needs them.

That said, Maire noted that this patch looks pretty specific to the Roku _screencasting_ stuff, which is apparently due to be ripped out anyway as being unused and untested. So instead of putting it behind a flag, we should just nuke it from orbit. But if the intent was to actually disable _screensharing_ (in the WebRTC sense), that's going to need a different patch. Recommendation was to followup with :dminor or :jib.

Comment 3

[Gregory Szorc [:gps]]

dminor: setting needinfo so this shows up on your WebRTC radar

dolske: is there a bug for nuking Roku screencasting? If so, should we dupe this?

Comment 4

[Dan Minor [:dminor]]

To get rid of WebRTC screensharing, you'll need to make changes to at least these two build files:
media/webrtc/trunk/webrtc/modules/desktop_capture/BUILD.gn
media/webrtc/trunk/webrtc/video_engine/BUILD.gn

and regenerate moz.build files according to the instructions here: https://firefox-source-docs.mozilla.org/build/buildsystem/gn.html

Some other changes may be required elsewhere to get things to link properly. We don't support screensharing on Android already, so it shouldn't be that much of a challenge to remove it on other platforms.

Let me know if I can be of help.

Comment 5

[Justin Dolske [:Dolske]]

(In reply to Gregory Szorc [:gps] from comment #3)
 
> dolske: is there a bug for nuking Roku screencasting? If so, should we dupe
> this?

Dunno, not my area. I'd probably point to the same people as comment 2 to find out more?