Setting Up a pacman Repository for Archlinux

Last night, I finally got around to recompiling my own vim binary through abs. I wanted X title bar support, and the python interpreter so that one of these days I can set up PHP debugging with x-debug.

Users of emacs can kindly redirect themselves to /dev/null. </religion>

Everything went off without a hitch; package compiled and installed fine, and I got a bonus gvim package to go with it. (On an unrelated note, anybody want a mint condition gvim package with ruby and python support compiled in? Has never even been opened; I don't even know if it works.) The dependencies are a little off (now requires libxt, ruby 1.9, and python 2.6), but I already had everything installed, so it was fine for me.

Then I went through and installed an ftp server on my latest test box and got the package added to the repository. It turns out that the name of the repo is important, which is a double edged sword. On the plus side, you can host multiple repositories on the same server without the huge directory tree required of other distros (*cough*ubuntu*cough*). On the other hand, it means that it took some trial and error to get the pacman.conf entry right:

[repository-name]
Server = ftp://hostname.example.com/

This actually downloads ftp://hostname.example.com/repository-name.db.tar.gz, which isn't what I would have expected. It's succinct, but means that you have to know the server's internal name for the repo (as opposed to, say, http://archive.ubuntu.com/ubuntu/dists/lucid/main/).

The other gotcha that wasn't clear from the Arch wiki is that the packages and the db file must live in the same directory. It looks like the following should work:

root@mirror:/srv/ftp# repo-add pkgs/vim-7.2-1-i686.pkg.tar.xz repository.db.tar.gz

and everything appears to work perfectly until you try and actually download repository/vim. The db entry doesn't store the full path, so you can simply move pkgs/*.tar.xz into the root of the ftp server and everything will magically start working.

Finally, pure-ftpd >> GNU inetutils ftpd. It supports IPv6, has rate-limiting, throttling, and chroot() built in, and permits anonymous, password-less logins. The motd at client connect I'm not crazy about, but that doesn't show up in pacman, so I don't much care. IPv6, on the other hand, means not having to deal with silly things like NAT. And we all know how well ftp works with NAT (hint: PASV is a hack that can now go the way of IE6).

So, now I have a native IPv6 arch repository that I can packages I compile from abs into. Let the hacking begin!

For those interested in what I'm up to:

[tingar]
Server = ftp://ftp.tingar.uni.cx/

:wq

Do the Wave...

My first abortive attempt at a Google Wave bot was an IRC <-> Wave bot that would let me look at IRC over Wave (or, more likely, Wave over IRC).

The second bot I've attempted actually works, though, so naturally I'm more proud of that one. Inspired in part by an Ars Technica article, my D&D group decided to investigate gaming over Wave. I still think that OpenRPG is a better overall solution, but in a pinch, Wave could work. So we added the bot that they used for the article and played around with it a little bit.

For those not familiar with how D&D die rolls work, I recommend D&D for Dummies, but the basics should suffice for this example: NdM indicates rolling N M-sided dice. For monopoly, you use 2d6 (two, six-sided dice). For D&D, the standard roll is 1d20, plus or minus some modifiers. From there, you build up more and more complicated expressions until you're a level 10 Rogue/Warlock with 22 Dex waving your +3 Dagger at the zombie and you roll up 1d20+5+6+1+3+1+3+1 vs Reflex (and yet still miss!).

But I digress. All those modifiers you add to a die should be cumulative and per total roll: 2d6+3 is two, six-sided dice, plus 3. The die rolling wave bot linked by Ars Technica treats the modifier as modifying each die, so you get two, six-sided-dice-plus-three, effectively doubling the modifier (1d6+3 + 1d6+3).

Well, I had a dice-roller before that kind of worked (from my IRC adventures), so I decided to take my work on version 2 of that and port it to Java. Why Java? Because I hate Python. And for a Wave robot, those are the only choices.

So, I loaded up my least favorite IDE, reminded myself why I hate Eclipse, switched to NetBeans, lost a hard drive (which means I owe the internet the obligatory "Back Up Your Data" blog post), forgot all about it for a couple days, installed NetBeans on a different computer, and settled in to write myself a bot. Ah, Java. Good times.

Normally, I'd use a Linux as my IDE of choice, but Netbeans and Eclipse both have plugins for deploying a project to Google App Engine (where all Wave bots call home), and I didn't want to have to worry about that part. Plus, Java is a library language, so integrated docs for the libraries is rather nice.

A wave robot is pretty simple, you register for events, and then write a handler for them. The handler in this case is a little compiler (yes, it lexes and parses the die roll into a syntax tree; I'm a bit of a masochist, apparently), and an "interpreter" that actually rolls the result. Borrowing from OpenRPG, it looks for a roll inside square braces and replaces the contents with the result:

[1d20+5+6+1+3+1+3+1] becomes [1d20+5+6+1+3+1+3+1 = (37)] (I rolled well). There's always more to do with it, but this is a good start for a weekend. To play with the bot, add die-roller@appspot.com to your Wave contacts and then invite it to your favorite dragon-slaying waves. The author asks only a modest share of the XP from any dragon slayed with the help of this tool.

Now for the ugly:

NOWHERE on the internet could I find this little "feature," so I'm going to warn people here. When replacing text in the Java API (TextView.replace()), Annotations get "shifted" by the difference in text length you're inserting. As do Range objects which completely enclose the area. For example:

Range r = new Range(0, 10); // a range from 0 to 1
textview.replace(new Range(1,9), "a bunch more text");
// r is now the range [0, 18] because 8 more characters were inserted

Unfortunately, this happens on Annotations that have already been added (in this jsonrpc call) as well, but incorrectly. They get shifted twice (or one-and-a-half times, or something...they always end up beyond where they should), so this code acts very strangely indeed:

while (!stack.empty()) {
  Range r = stack.pop();
  ...
  textview.replace(r, a_string);
  textview.setAnnotation(r, "style/color", "#336699");
  ...
}

The "correct" way to do this is to keep track of an offset and then shift the Annotations yourself:

int offset;

for(Range r: stack) {
  ...
  textview.replace(new Range(r.getStart()+offset, r.getEnd()+offset), a_string);
  textview.setAnnotation(new Range(r.getStart()+offset, r.getEnd()+offset), "style/color", "#336699");
  offset += a_string.length() - (r.getEnd() - r.getStart());
  ...
}

Obviously, the more Java way of doing this would involve several dozen more Factorys, but at least Google embraces Python and so doesn't do things the "Java way."

Oh, and back up your data.

:wq

@ IN SOA localdomain. aaron.localdomain.

So, I finally got my networking set up at home a couple months ago. There's a little web interface to add computers to the network, which automatically updates DHCP and DNS and allows them on wireless.

I also have an IPv6 tunnel and auto-configuration for my /48 (rDNS is annoyingly difficult, thanks to comcast).

So, of course, this weekend I got to break it all!

I've been using dnsmasq on my linux server to do DHCP and DNS. Basically, it looks through /etc/hosts and /etc/ethers and figures out the answers to queries from there. It also has support for built-in TFTP and can send the right options to be able to PXE boot computers. Neat.

But, my router is running FreeBSD, and I want to reload my linux box to OpenSolaris. The linux machine is basically a fileserver, so reloading it means I can use ZFS. Here's the overall plan:

1. reload fileserver
2. ???
3. profit

Step 1 requires that I move the infrastructure (DHCP, DNS, TFTP, etc.) onto the router, which I've been meaning to do anyway. I've got linux compatibility mode turned on on the router, so I could probably run dnsmasq on there, but that's not very impressive. Bind9 and ISC dhcpd is a much cooler option.

Enter `svn branch`.

Today, I spent my time rewriting my networking automagic (the scripts, not the daemon) to generate DNS zone files from my networking database. Of course, the cron will still run on the db server, since I don't want to be firing up make and perl on the router every 5 minutes. Sure, I could, but the db would be hella slow. Now I've got DNS running on 2 boxes, and as soon as I figure out all the merging and branching and moving to make it work correctly, I'll be able to shut down the DNS server on linux.

DHCP will, of course, require me to learn yet another config file format, but it looks similar, and I should just have to tweak the scripts a little bit to make them output the new format. The only hard part of dnsmasq -> named was the conversion from /etc/hosts to the IPv6 PTR records. About 30 lines of perl run through the whole shooting match for that; IPv4 is just an extra sed script.

:wq