YoctoIRCd is an extremely minimalistic IRC server with only one purpose: send the MOTD to clients that connect to it and disconnect them immediately. Its intended use is for servers that listen on SSL-only; YoctoIRCd can provide a (non-SSL) message informing users trying to connect on the default port that they'll have to use a different port with SSL enabled. It also makes a good fallback server that can relay messages about downtime, etc. while the main IRC server is down. It also has an extremely simple (read: non-standard-compliant) HTTP server that just sends the MOTD and disconnects, as well. The HTTP server can be disabled, in which case it won't be compiled at all.
YoctoIRCd requires a C compiler to build, and nothing but the C standard library and a POSIX environment to run. YoctoIRCd officially supports FreeBSD and Linux, but should run in any other POSIX-ish environment. Windows is not supported.
To compile YoctoIRCd, download it and run make in the folder where you have
the source. By default, yoctoircd will be built in release mode. See the
"Debugging" section for information about creating a debug build.
For advanced users, you can edit some compile-time configuration in config.h.
This is where you can disable the HTTP server as well as changing buffer sizes
and tweak how other internals work.
If for whatever reason you do not have make on the system where you're trying
to compile YoctoIRCd, you can compile it with something similar to cc -Os -o yoctoircd src/*.c in the folder where the source is.
A sample configuration for YoctoIRCd is provided as yoctoircd.cfg. You should
copy it with a different name (so it doesn't get overwritten on updates) before
editing it. The sample configuration file is documented, but for convenience,
here are the configuration options available:
Port: The TCP port to listen onTimeout: The maximum amount of time a client can be connected (in seconds)MotdPath: The path to the file containing the MOTDServerAddress: The address of the server (no spaces)ServerName: The nickname of the serverChrootFolder: The folder tochrootinto (optional, requires root)SetUser: The user tosetuidto (optional, requires root)SetGroup: The group tosetgidto (optional, requires root)
NOTE: The configuration parser is quite strict; comments (beginning with
#) must start at the beginning of the line and any unrecognized option will
cause an error.
Just run ./yoctoircd $PATH_TO_CONFIG, replacing $PATH_TO_CONFIG with the
path to the configuration file you created.
You can update the MOTD without stopping YoctoIRCd. To do so, update the MOTD
file that your configuration file points to, then send a SIGUSR1 signal to
YoctoIRCd. To do so, you can use the one-liner killall -USR1 yoctoircd. The
child processes will ignore SIGUSR1, but the parent process will reload the
MOTD when it recieves the signal.
You can update the configuration file without stopping YoctoIRCd, just like
updating the MOTD. Instead of sending SIGUSR1, send SIGUSR2 in the exact
same manner.
NOTE: You cannot update the port that YoctoIRCd listens on or any security
options (ChrootFolder, SetUser, and SetGroup) with SIGUSR2. You must
restart YoctoIRCd. You can, however, change the path to the MOTD file. YoctoIRCd
will update the MOTD automatically, as well.
Though I've done my best to eliminate bugs, it's impossible to get rid of all of them. That being said, it's possible that some of the bugs may cause security flaws. I've been extra careful to avoid those kinds of bugs, but it's still best to err on the side of caution.
YoctoIRCd supports chroot, setuid, and setgid through configuration
options. For the best security, you should create a user and group just for
YoctoIRCd, create a folder with the configuration file and the MOTD (and nothing
else), set the folder and files read-only for YoctoIRCd, then set ChrootFolder
to that folder, and SetUser and SetGroup to that user and group. For those
options to work, however, you will need to run yoctoircd as root. If you do
so, it will drop to the specified user and group as soon as possible. If you
have set those security options, but don't run yoctoircd as root, it will
cause an error and refuse to run because it will be unable to use chroot,
setuid, and setgid.
YoctoIRCd forks a child process for each connection. Each child process sets an alarm to go off after the timeout has been reached, which will close the connection and kill the process. Because the child process does not write to that much memory, the forking should be fairly inexpensive on COW systems, such as Linux. Even on systems that don't have COW forking, YoctoIRCd's memory usage is low enough that forking shouldn't have an excessively large overhead. A threaded mode may be added in the future.
To produce a debug build, first set your CFLAGS to enable debug information.
For example, if you're using bash and gcc, run export CFLAGS="-ggdb -O0"
then make debug. It's important to both add debug flags to CFLAGS as well as
using the debug target instead of the default release target. The release
target runs strip over the built binary which strips all the debug information
that the C compiler added. Also, setting your CFLAGS will remove the
-DNDEBUG from the default CFLAGS, which will enable assertions.
As noted in the source files, YoctoIRCd is licensed under the Apache License,
Version 2.0. A copy of the license
is also available in the source distribution, named LICENSE.md. LICENSE.md
is the plain-text version ported to Markdown, using the HTML version as a
guide.
If you use YoctoIRCd and find it useful, it would be greatly appreciated if you donated to the project. Donations are primarily accepted through Flattr although other arrangements can be made by contacting me through GitHub if you don't want to use Flattr.
