HACKING

A lot of people have tried to hack gaim, but haven't been able to because
the code is just so horrid. Well, the code isn't getting better anytime
soon, so to help all you would-be hackers help out gaim, here's a brief
tutorial on how gaim works. I'll quickly describe the logical flow of
things, then what you'll find in each of the source files. Hopefully
that's enough to get most of you going.

If you're going to hack gaim, PLEASE, PLEASE PLEASE PLEASE send patches
against the absolute latest CVS. I get really annoyed when I get patches
against the last released version, especially since I don't usually have
a copy of it on my computer, and gaim tends to change a lot between
versions. (I sometimes get annoyed when they're against CVS from 3 days
ago, but can't complain because it's usually my fault that I haven't
looked at the patch yet.) To get gaim from CVS (if you haven't already),
run the following commands:

$ export CVSROOT=anonymous@cvs.gaim.sourceforge.net:/cvsroot/gaim
$ cvs login
(hit enter as the password)
$ cvs co gaim
(you'll see it getting all of the files)
$ cd gaim
$ ./gen

You'll now have your normal gaim tree with ./configure and all. (If you
want to make your life really simple, learn how CVS works. CVS is your
friend.)

There's one little thing that's just a pet peeve, and it's really stupid.
In ./configure there's an --enable-debug option. This does two things:
compiles with -Wall, and prints debugging information to stdout. The
debugging information is printed to the debug window (which can be turned
on in the preferences) whether or not --enable-debug was selected. Most
of the information that's printed is useless anyway though; so the
--enable-debug option really doesn't do a whole lot.

This was written around August 8, 2000. It's now August 15, 2000, and I'm
sure a lot of it is already out of date.


PROGRAM FLOW
============

Before gaim does anything you can see, it initializes itself, which is
mostly just reading .gaimrc (handled by the functions in gaimrc.c). It
then draws the login window by calling show_login, and waits for input.

At the login window, when "signon" is clicked, dologin() is called. This
in turn calls serv_login, which checks to see if you want to use Oscar or
TOC, and calls oscar_login or toc_login appropriately. We'll assume TOC
for the rest of this discussion; Oscar has a lot of bad hacks to get it
working that I don't even want to think about.

After you're signed in (I'll skip that discussion - I doubt many people
are going to change the login process, since it pretty much just follows
PROTOCOL), Gaim draws the buddy list by calling show_buddy_list, and
waits for input from two places: the server and the user. The first place
it gets input from after signon is invariably the server, when the server
tells Gaim which buddies are signed on.

When there is information ready to be read from the server, toc_callback
is called (by GDK) to parse the incoming information. On an UPDATE,
serv_got_update is called, which takes care of things like notifying
conversation windows of the update if need be; notifying the plugins;
and finally, calling set_buddy.

set_buddy is one of the most frequently called functions in gaim, one of
the largest functions in gaim, and probably one of the buggiest functions
in gaim. It is responsible for updating the pixmaps in the buddy list;
notifying plugins of various events; updating the tooltips for buddies;
making sounds; and updating the ticker. It's also called once per online
buddy every 20 seconds (by GTK through update_all_buddies).

When the user opens a new conversation window, new_conversation is called.
That's easy enough. If there isn't a conversation with the person already
open (checked by calling find_conversation), show_conv is called to
create the new window. All sorts of neat things happen there, but it's
mostly drawing the window. show_conv is the best place to edit the UI. Be
prepared for some incredibly bad GTK programming. (Rob's fixing this as
we speak no doubt.)

That's pretty much it for the quick tutorial. I know it wasn't much but
it's enough to get you started. Make sure you know GTK before you get too
involved. Most of the back-end stuff is pretty basic; most of gaim is GTK.


SOURCE FILES
============

about.c:
  Not much to say here, just a few basic functions.

aim.c:
  This is where the main() function is. It takes care of a lot of the
  initialization stuff, and showing the login window. It's pretty tiny
  and there's not really much to edit in it. Watch out for bad Oscar
  sign in hacks.

away.c:
  This takes care of most of the away stuff: setting the away message
  (do_im_away); coming back (do_im_back); drawing the away window;
  etc. To be honest I haven't looked at this file in months.

browser.c:
  Code for opening a browser window. Most of the code is trying to deal
  with Netscape. The most important function here is open_url. Have fun.

buddy.c:
  This takes care of not only nearly everything buddy-related (the buddy
  list, the permit/deny lists, and the window), but also a lot of the
  code flow and util functions. Look for good things like find_buddy,
  set_buddy, and signoff() here.

buddy_chat.c:
  This takes care of the buddy chat stuff. This used to be a lot bigger
  until the chat and IM windows got merged in the code. Now it mostly
  just takes care of chat-specific stuff, like ignoring people and
  keeping track of who's in the room. This is also where the chat window
  is created.

conversation.c:
  This is where most of the functions dealing with the IM and chat windows
  are hidden. It tries to abstract things as much as possible, but doesn't
  do a very good job. This is also where things like "Enter sends" and
  "Ctrl-{B/I/U/S}" options get carried out (look for send_callback). The
  chat and IM toolbar (with the B/I/U/S buttons) are both built from the
  same function, build_conv_toolbar.

dialogs.c:
  A massive file with a lot of little utility functions. This is where
  all of those little dialog windows are created. Things like the warn
  dialog and the add buddy dialog are here. Not all of the dialogs in
  gaim are in this file, though. But most of them are. This is also
  where do_import is housed, to import buddy lists.

gaimrc.c:
  This controls everything about the .gaimrc file. There's not really much
  to say about it; this is probably one of the better designed and easier
  to follow files in gaim. The important functions are towards the bottom.

gnome_applet_mgr.c:
  A hideous creation from the days before I started working on gaim. Most
  of it works, but it has functionsLikeThis. I hate looking at this
  file, but I'm too lazy to change the functions. The best functions
  are things like set_applet_draw_open, whose sole purpose is to set a
  global variable to TRUE.

gtkhtml.c:
  This is really just one big hack. It started off as an HTML widget that
  was written for Gnome as far as I can tell. The current version is
  huge, requires way too many libs, and is too hard to upgrade to. But
  we've managed to hack this poor old version into basically what we
  need it for. I recommend not looking at this file if you want to save
  your sanity.

gtkticker.c:
  Syd, our resident GTK God, wrote a GtkWidget, GtkTicker. This is that
  widget. It's cool, and it's tiny.

html.c:
  Don't ask my why this is called html.c. Most of it is just grab_url,
  which does like the name says; it downloads a URL to show in the
  GtkHTML widget.  http.c would be a more appropriate name, but that's OK.

idle.c:
  There is a very good reason why this file is still on version 1.1
  in CVS.  The entire thing is #if 0'd out. I haven't ever really taken
  a good look at it, but I think what it was supposed to have done is
  set you as being away when a screensaver came on.

network.c:
  This has two functions: get_address and connect_address, both of which
  call proxy functions. If you want to see how these are used, look at
  toc.c and/or rvous.c. These are really just front-ends to the proxy
  stuff; use these instead of calling the proxy functions.

oscar.c:
  One big hack of copied code. This is supposed to be the libfaim tie-in
  in gaim. Most of it is just copied straight from faimtest, the small
  program that comes with libfaim. I'm not even sure how half of it works,
  if that makes you feel any better.

perl.c:
  This was basically copied straight from X-Chat through the power of
  the GPL.  Perl is the biggest, most confusing piece of C code I've ever
  seen in my life (and keep in mind I'm a gaim hacker). I have a basic
  idea of what's going on in it, but I couldn't tell you exactly. The
  top half sets up perl and tells it what's going on and the bottom half
  implements the AIM module.

plugins.c:
  This is the "plugin plug", as the file states. This file is probably
  the only file in all of gaim that at the top has all of the functions
  and global and static variables named out for you. It makes reading
  it a little easier, but not by much. A lot of the code in here deals
  with the plugin window rather than the plugins themselves.

prefs.c:
  The important function in here is build_prefs, but the most useful
  function is gaim_button. build_prefs draws the window, and calls
  gaim_button probably 30 or 40 times. (I don't really wanna run grep
  | wc to count.) This is where you add the toggle button for gaim
  preferences. It's very simple, and if you look at a couple of the
  calls to gaim_button you'll figure it out right away.

proxy.c:
  This is where the bulk of the actual networking code is done. The big
  function here is proxy_connect, which will connect through the proxy
  setup you've chosen (most of which don't work...) or just regularly.

rvous.c:
  This was originally going to be the stuff for all of the Buddy Icon
  and Voice Chat stuff, but I got really sick of protocol hacking really
  quick.  Now it only houses the file transfer stuff, which only works
  for TOC.

server.c:
  This is where all of the differentiation between TOC and Oscar is
  done.  Nearly everything that's network related goes through here
  at one point or another. This has good things like serv_send_im and
  serv_got_update. Most of it should be pretty self-explanatory.

sound.c:
  The big important function is play_sound, which plays one of 4 (actually
  6) sounds. One of the sounds is called in 3 different events, which
  is why there are actually 6 sounds. This then calls play which then
  checks for esd, then nas if that's not available, then falls back
  to /dev/audio.

ticker.c:
  Syd is just so cool. I really can't get over it. He let me come
  visit him at Netscape one day, and I got to see all of their toys
  (don't worry, I'm under an NDA). Anyway, this file is for the buddy
  ticker. This is also a damn cool file because it's got all of the
  functions that you'd want right up at the top. Someday I want to be
  as cool as Syd.

toc.c:
  This handles everything TOC-related, including parsing gaim's buddy
  list.  Most of this file is toc_callback, which parses the incoming
  information from the server. I really don't like TOC though.

util.c:
  There's not really a lot of cohesion to this file; it's just a lot of
  stuff that happened to be thrown into it for no apparent reason. None
  of it is particularly tasty; it's all just utility functions. Just
  like the name says.


So that's our little tour of the internals of Gaim. It's really not
difficult to figure out if you've spent any time with GTK. I'm looking
forward to getting all of your patches :)