make launch() check for ControlPort status in a more robust way

[hellais]

As documented in https://github.com/meejah/txtorcon/blob/master/txtorcon/controller.py#L131, it seems like txtorcon checks simply for the first bootstrapping line to learn if the control port is open, it seems like this is actually a bit fragile and sometimes leads to problems.

It would be better if instead it looked for the line:

Apr 16 18:39:46.600 [notice] Opening Control listener on 127.0.0.1:9051

or

Feb 14 14:21:46.828 [notice] Opening Control listener on /home/f/tor-browser_en-US/Browser/TorBrowser/Data/Tor/control.socket

[meejah]

👍 this sounds like a great idea.

Also probably fairly easy, great for anyone looking for a "first txtorcon PR".

[KyleRConway]

@meejah -- I'm looking for a "first txtorcon PR" -- would love to work on this one.

[meejah]

Hi @KyleRConway, great!

If you use IRC, the best way to real-time chat with me is to join the #tor-dev channel on the OFTC network (I'm "meejah" there). Or we can just use this ticket to communicate if that's easier.

launch() starts here: https://github.com/meejah/txtorcon/blob/master/txtorcon/controller.py#L53 -- it's kind of long, but the interesting part will actually be in TorProcessProtocol (https://github.com/meejah/txtorcon/blob/master/txtorcon/controller.py#L1221) and outReceived. This is where any output from the Tor process will be received. Currently, it just waits for any output right now. For this ticket, we should buffer (some of) the received lines and look for "Opening control listener" or similar before trying the connections.

[meejah]

If you don't know Twisted or async programming and want to learn more about that aspect, this is a great tutorial: http://krondo.com/an-introduction-to-asynchronous-programming-and-twisted/