[Freeciv-Dev] Re: client/server authentication (PR#1767)

["Mike Kaufman" <kaufman@xxxxxxxxxxxxxxxxxxxxxx>]

attached are the last two of a second set of three patches for
client/server authentication.

A lot of code has changed a bunch:

o added gtk-2.0 client (probably not canonical GTK2, vasc, will have to
  look at it)
o removed pconn->password, we no longer need it
o made "unconnecting from  %s" to "detaching from %s" as GB wanted
o password check now checks that the password does not contain spaces
o encapsulated more code in #ifdef AUTHENTICATION_ENABLED #endif
o added configure magic (badly, Per or Jason or somebody will have to fix)
o totally rewrote the database (see below for gory detail)
  o db is in ascii
  o it locks
o added a freeciv/misc/db directory for the user_database (can be changed)
o added some comments for Raimar.

Things that didn't happen:

o didn't fix the readline completion for /take. This turns out to be nasty
  since /take can take one or two arguments and the first argument is either
  a user or player depending on the existance of the second argument. Maybe
  later.
o didn't fix Chris's complaint on the client. This might be fixable, I'll 
  be in touch Chris (most people won't ever see this problem).

How to test: 

% gunzip auth4-5s.diff.gz auth5-6i.diff.gz
% cd freeciv
% patch -p1 < auth4-5s.diff
% patch -p1 < auth5-6i.diff
% ./autogen --enable-auth [--enable-client=gtk2] # pointless otherwise
% cd misc; make; cd .. # this is a configure problem, see below
% make

Gory database details:

I told paulz that I would make user database work by calling into an
external program. I lied (sorry paul). I discovered after doing this that
it is much too ugly and potentially fragile to put in the freeciv codebase.

Instead, I came up with a better idea (at least I think so). Since anybody
who runs a large public server (thus needing auth, and being large needs a
real database solution) will be compiling from source anyway, I decided
that "pluggable" libraries is the way to go. 

No, this is not dlopen(). the freeciv user database basically consists of a
library which is named libuserdb.a which is built in misc/db/ This library
calls exactly one function in the server (connecthand.c:handle_db_lookup())
If someone wants a custom database solution, then he simply replaces
libuserdb.a with another when compiling the server. 

There is a default database which comes with freeciv and will be compiled
(kinda) when auth is enabled. If you want a custom database, you can do:

% ./autogen --enable-auth=/path-to-db-lib/libuserdb.a

and then compile after you've prepared the external library. To enlighten
you, I have attached a toy database (which you can see is based quite a
bit on the default one), which actually does fork a process which does the
database lookup and returns the answer through exit status.

To play with it, make sure you edit the accompanying Makefile and change
USER_DB_PROGPATH and USER_DB_PATH before compiling. It's a good bet you
don't have the default directories.

The API is really simple: see misc/db/user_db.h for the functions which an
external library must have to survive.

There are two configure bugs (at least). 1. If misc/db/libuserdb.a
isn't compiled before the server, can't find it as a dependency. The
current kludge is as above, before doing the global make, do make in misc/
2. If you specify an external library, the server should be recompiled, but
doesn't.

The configure patch is a real kludge, somebody should clean it up. Also,
I'm not sure that the external library option should be wrapped into the
enable-auth option. Also, in the default code, the database file location
is not configurable. It should be. Right now it's named
freeciv_user_database and it will be created in the same directory that the
server is started in.

-mike

auth4-5s.diff.gz
Description: auth4-5s.diff.gz

auth5-6i.diff.gz
Description: auth5-6i.diff.gz

toy_external_db.tar.gz
Description: toy_external_db.tar.gz