I've got a bunch of notes from perusing the source code trying to understand it.
It sounds like it would be a great project for someone that is just getting into Tor and already knows C (I hope I didn't just volunteer myself for the project...) My question would be, how likely is it that the architecture that you just described would be changing anytime soon? I think any documentation written to such an end would have to strike a balance between being detailed enough to be useful and not too detailed in that parts of it get outdated rather quickly. I was thinking about doing this for the JTor implementation as I have been digging into that a decent amount the last few weeks. On Mon, Mar 7, 2011 at 6:55 PM, Nick Mathewson <ni...@freehaven.net> wrote: > On Sat, Mar 5, 2011 at 7:29 AM, <hi...@safe-mail.net> wrote: >> I mean _really_ work. >> >> (I already know how it protects your anonymity.) >> >> What happens from the moment you start the Tor program? What's the first >> thing it does, the next thing, and so forth? I've never seen a detailed >> technical illustration of how it works on a technical level. > > You mean, which parts of the code call what, and how they all fit > together? I'm afraid we haven't written anything like that. I'd love > for somebody to start writing one, but for now, learning how the code > all fits together will require you to read some C. > > If you're still interested, here are some good points to start with: > - The tor program does most of its work in the main thread. The > main thread is written launches operations in response to events, > which include network IO, timers, and signals. Tor uses libevent to > notice these events. The starting point for handling network IO > events (in 0.2.2) is conn_read_callback and conn_write_callback. The > starting point for handling signals is signal_callback. The starting > point for invoking periodic timers is second_elapsed_callback. These > are all in src/or/main.c. > - There are also subthreads to handle CPU-intensive tasks. Right > now, they only handle onionskins. > - To see how the program starts up, start with the function > tor_main() in src/or/main.c. When Tor is run, it invokes > do_main_loop(), which sets up more of the global state, and then > spends most of its time in a loop. The loop's main job is to call > event_base_loop(): this is where Tor spends most of its time. > > Again, this is just a sketch of interesting points to start reading a > top-down tour of the program, and isn't a "tor internals guide" by any > means. If somebody has time to write one someday, that would rock. > > > cheers, > -- > Nick > _______________________________________________ > tor-talk mailing list > tor-talk@lists.torproject.org > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk > _______________________________________________ tor-talk mailing list tor-talk@lists.torproject.org https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk
