GettingStarted.md 7.6 KB
Getting started in Tor development
Congratulations! You've found this file, and you're reading it! This means that you might be interested in getting started in developing Tor.
(This guide is just about Tor itself--the small network program at the heart of the Tor network--and not about all the other programs in the whole Tor ecosystem.)
If you are looking for a more bare-bones, less user-friendly information dump of important information, you might like reading doc/HACKING instead. You should probably read it before you write your first patch.
Required background
First, I'm going to assume that you can build Tor from source, and that you know enough of the C language to read and write it. (See the README file that comes with the Tor source for more information on building it, and any high-quality guide to C for information on programming.)
I'm also going to assume that you know a little bit about how to use Git, or that you're able to follow one of the several excellent guides at http://git-scm.org to learn.
Most Tor developers develop using some Unix-based system, such as Linux, BSD, or OSX. It's okay to develop on Windows if you want, but you're going to have a more difficult time.
Getting your first patch into Tor
Once you've reached this point, here's what you need to know.
1) Get the source.
We keep our source under version control in Git. To get the latest
version, run
git clone https://git.torproject.org/git/tor
This will give you a checkout of the master branch. If you're
going to fix a bug that appears in a stable version, check out the
appropriate "maint" branch, as in:
git checkout maint-0.2.7
2) Find your way around the source
Our overall code structure is explained in the "torguts" documents,
currently at
git clone https://git.torproject.org/user/nickm/torguts.git
Find a part of the code that looks interesting to you, and start
looking around it to see how it fits together!
We do some unusual things in our codebase. Our testing-related
practices and kludges are explained in doc/WritingTests.txt.
If you see something that doesn't make sense, we love to get
questions!
3) Find something cool to hack on.
You may already have a good idea of what you'd like to work on, or
you might be looking for a way to contribute.
Many people have gotten started by looking for an area where they
personally felt Tor was underperforming, and investigating ways to
fix it. If you're looking for ideas, you can head to our bug
tracker at trac.torproject.org and look for tickets that have
received the "easy" tag: these are ones that developers think would
be pretty simple for a new person to work on. For a bigger
challenge, you might want to look for tickets with the "lorax"
keyword: these are tickets that the developers think might be a
good idea to build, but which we have no time to work on any time
soon.
Or you might find another open ticket that piques your
interest. It's all fine!
For your first patch, it is probably NOT a good idea to make
something huge or invasive. In particular, you should probably
avoid:
* Major changes spread across many parts of the codebase.
* Major changes to programming practice or coding style.
* Huge new features or protocol changes.
4) Meet the developers!
We discuss stuff on the tor-dev mailing list and on the #tor-dev
IRC channel on OFTC. We're generally friendly and approachable,
and we like to talk about how Tor fits together. If we have ideas
about how something should be implemented, we'll be happy to share
them.
We currently have a patch workshop at least once a week, where
people share patches they've made and discuss how to make them
better. The time might change in the future, but generally,
there's no bad time to talk, and ask us about patch ideas.
5) Do you need to write a design proposal?
If your idea is very large, or it will require a change to Tor's
protocols, there needs to be a written design proposal before it
can be merged. (We use this process to manage changes in the
protocols.) To write one, see the instructions at
https://gitweb.torproject.org/torspec.git/tree/proposals/001-process.txt
. If you'd like help writing a proposal, just ask! We're happy to
help out with good ideas.
You might also like to look around the rest of that directory, to
see more about open and past proposed changes to Tor's behavior.
6) Writing your patch
As you write your code, you'll probably want it to fit in with the
standards of the rest of the Tor codebase so it will be easy for us
to review and merge. You can learn our coding standards in
doc/HACKING.
If your patch is large and/or is divided into multiple logical
components, remember to divide it into a series of Git commits. A
series of small changes is much easier to review than one big lump.
7) Testing your patch
We prefer that all new or modified code have unit tests for it to
ensure that it runs correctly. Also, all code should actually be
_run_ by somebody, to make sure it works.
See doc/WritingTests.txt for more information on how we test things
in Tor. If you'd like any help writing tests, just ask! We're
glad to help out.
8) Submitting your patch
We review patches through tickets on our bugtracker at
trac.torproject.org. You can either upload your patches there, or
put them at a public git repository somewhere we can fetch them
(like github or bitbucket) and then paste a link on the appropriate
trac ticket.
Once your patches are available, write a short explanation of what
you've done on trac, and then change the status of the ticket to
needs_review.
9) Review, Revision, and Merge
With any luck, somebody will review your patch soon! If not, you
can ask on the IRC channel; sometimes we get really busy and take
longer than we should. But don't let us slow you down: you're the
one who's offering help here, and we should respect your time and
contributions.
When your patch is reviewed, one of these things will happen:
* The reviewer will say "looks good to me" and your
patch will get merged right into Tor. [Assuming we're not
in the middle of a code-freeze window. If the codebase is
frozen, your patch will go into the next release series.]
* OR the reviewer will say "looks good, just needs some small
changes!" And then the reviewer will make those changes,
and merge the modified patch into Tor.
* OR the reviewer will say "Here are some questions and
comments," followed by a bunch of stuff that the reviewer
thinks should change in your code, or questions that the
reviewer has.
At this point, you might want to make the requested changes
yourself, and comment on the trac ticket once you have done
so. Or if you disagree with any of the comments, you should
say so! And if you won't have time to make some of the
changes, you should say that too, so that other developers
will be able to pick up the unfinished portion
Congratulations! You have now written your first patch, and gotten
it integrated into mainline Tor.