[tbb-dev] How Tor Browser interacts with Tor source code

[David Fifield]

On Sun, Sep 11, 2016 at 07:02:10PM +0000, Liu, Zhuotao wrote:
> I have a problem of understanding how Tor browser interacts with the Tor source
> code. My understanding is that in order to use Tor, there much be a Tor client
> instance running locally. But when using Tor browser, I did not notice the
> existence of Tor client at all (which is good for usability). However, I do not
> understand how the Tor browser interacts with Tor client in background? Any
> idea is greatly appreciated. :) 

Tor is started by a Firefox addon called Tor Launcher:
https://trac.torproject.org/projects/tor/wiki/doc/TorBrowser/Hacking#TorLauncher
https://gitweb.torproject.org/tor-launcher.git/tree/

Tor Launcher is what you see when you run Tor Browser for the first time
and it gives you the Connect/Configure option. It's also Tor Launcher
that draws the progress bar on startup before the browser window
appears. You can see Tor Launcher in about:addons (along with NoScript,
HTTPS Everywhere, and Torbutton).