2008

New Knab modules

I've recently been doing a lot of hacking on Knab, which is the software behind the #clug IRC bot, Spinach. I've contributed a number of new modules, most of which are running on Spinach and are available from the main Bazaar repository.

Events

This module is basically a calendar feature which can store and retrieve events such as birthdays. It also handles recurring events (both with rules1 or multiple dates).

<cocooncrash> Something happens on 21 December 2008 at 15:00
<Knab> yessir
<cocooncrash> When is something?
<Knab> something is on Sunday the 21st of December 2008 at 15:00:00
<cocooncrash> Forget event something
<Knab> I've forgotten something

<cocooncrash> My birthday happens on 22 March every year
<Knab> sure
<cocooncrash> How long until cocooncrash's birthday?
<Knab> your birthday is 13 weeks and 1 day away
<cocooncrash> How many days until my birthday?
<Knab> your birthday is 92 days away

<cocooncrash> When is Easter in 2010?
<Knab> Sun 4 Apr
<cocooncrash> What's happening on Tuesday
<Knab> National Chocolate Covered Anything Day and Day of Reconciliation
<cocooncrash> Search events for Outsider 
<Knab> Found: Be Friendly To Outsider Day, Be Hard On Outsider Day, Outsider's birthday, Outsider's dad's birthday,  (showing 4 of 4 results)

Twitter

This module retrieves messages posted on Twitter and identi.ca.

<cocooncrash> Last twitter update by iolproofreader
<Knab> "The ANC in the Eastern Cape is making it clear: it's either you're with us or not."
<cocooncrash> twitter 1067135354
<Knab> iolproofreader: ""Friend chases after golfer shot" http://tinyurl.com/4dn2lx"
<cocooncrash> http://twitter.com/iolproofreader/status/1067135354
<Knab> iolproofreader: "Police are planning on more patrols and more scrutiny for travellers crossing the border of Swaziland and Mozambique."

URLLengthen

This modules discovers the URL which a shortened URL redirects to.

<cocooncrash> http://is.gd/1D
<Knab> http://google.com/

URLShorten

This module creates a short URL using is.gd.

<cocooncrash> shorten http://google.com/
<Knab> http://is.gd/1D

HTTP

This module retrieves an HTTP URL and returns the result of the request.

<cocooncrash> get http://google.com
<Knab> 200 OK "Google"
<cocooncrash> Is google.com up?
<Knab> Yes, it's up
<cocooncrash> Is Twitter down?
<Knab> No, it's just you

GoogleDefine

This module gets definitions using Google.

<cocooncrash> gdefine spinach
<Knab> "dark green leaves; eaten cooked or raw in salads  ", "The Spinach (Eulithis mellinata) is a moth of the family Geometridae.

Subversion

This module retrieves commit messages from a Subversion repository.

<cocooncrash> last commit
<Knab> r721 by trb143 7 hours ago: "Update UI a bit to display columns"
<cocooncrash> commit 700 full
<Knab> r700 by mgorven on 2008/12/15 at 21:14:26 UTC: "Set non-existing config entries if requested with a default value, and create ~/.openlp when saving config file. " M /openlp-2/trunk/openlp/core/utils/linregistry.py, M /openlp-2/trunk/openlp/core/utils/confighelper.py

SummonJabber

This module summons people by sending them a message via Jabber.

<cocooncrash> cocooncrash.summon.jabber is cocooncrash@example.com
<Knab> gotcha
<cocooncrash> summon cocooncrash
<Knab> I've summoned cocooncrash via Jabber

Feeds

This module retrieves RSS and Atom feeds.

<cocooncrash> Add feed http://www.news24.com/news24RSSFeed/0,,2,00.xml as News24
<Knab> okay
<cocooncrash> latest articles from news24
<Knab> 0: "SA's first San party launches", 1: "Pakistan mall collapse: 3 dead", 2: "Iran warship to fight pirates", 3: "Westwood storms into lead", 4: "US Embassy given the boot", 5: "Jennifer Aniston's chilli Xmas"
<cocooncrash> article 0 from News24
<Knab> "SA's first San party launches" http://www.news24.com/News24/South_Africa/Politics/0,,2-7-12_2444493,00.... : The first San political party has been launched at Upington in the Northern Cape. 
<cocooncrash> article /Palin/ from news24
<Knab> "Drama in Palin household" http://www.news24.com/News24/World/News/0,,2-10-1462_2444295,00.html : The mother of  an 18-year-old man who plans to marry Alaska Governor Sarah Palin's  pregnant daughter, Bristol, has been arrested on drug charges.
<cocooncrash> list feeds
<Knab> m&g, clug park, haiybo, TechCrunch, onion, News24
<cocooncrash> remove news24 feed
<Knab> okay

  1. This feature is provided by the Date::Manip library. 

Playing with Python and IRC

I wrote three IRC bots in [Python][] this last week (although one was a rewrite). They probably aren't very useful to most people, but I'm going to share them anyway in case someone finds them interesting.

The first one was prompted by [Adrian][], who is maintaining a [countdown][] until his wedding as a factoid in [Spinach][]. Since [Knab][] doesn't actually support countdowns, it has to be updated manually. This clearly isn't the Right Way to do this, and so I hacked together a [script][irccountdown] which connects to IRC and teaches Spinach the updated factoid. I run this as a daily [cronjob][] to keep the countdown up to date.

As is usually the case with Python, there was already a library for accessing IRC, namely [irclib][]. It isn't documented very well, but has a couple example scripts which are fairly easy to follow. It follows an event based model, so you write functions which will be called when certain events occur (such as receiving a message).

The final of the [Currie Cup][] was held on Saturday (which my team (the [Sharks][]) won), and I followed the match online using [SuperSport's][] live score site1. I then thought that it would be cool to have the score announced on IRC when it changed, and since I was bored I wrote a simple [bot][rugby] to do this. It worked well, but was very simple in that it only supported one hardcoded channel and one hardcoded game.

Since I was also bored on Sunday I [rewrote][rugbybot] this bot properly. I added a subscription mechanism so that channels and users can subscribe and unsubscribe to games by sending the bot a command. It's mostly working except for listing the available games (since there aren't any rugby games coming up which means that I can't test it ;-) ). Games are specified by the ID used by SuperSport's site, and finding the right ID is currently a manual process.


  1. I'm not really a sports fan — I just enjoy bragging when we do win ;-) 

Sharing links from Konqueror, including to IRC

I follow the main feeds of a couple social news sites (namely Digg, Reddit and Muti). When I find an article which I like, I go back and vote it up on the site. However, when I come across good articles via other sources, I don't submit them to these news sites (or try to find out if they've already been submitted) simply because it's too much effort.

When I started aggregating my activity on these sites on my blog and on FriendFeed, I needed a way to share pages that I didn't get to via one of these social news sites. I ended up setting up Delicious because I found a plugin for Konqueror which made it easy to bookmark pages.

I still wanted to solve the original problem though, and so started looking for an easy way to submit links to these sites from Konqueror. Konqueror has a feature called service menus which allows you to add entries to the context menu of files. I then needed to work out how to submit links to these services, which turned out to simply involve loading a URL with a query parameter specifying the link you want to share.

I created entries for Reddit, Digg, Muti, Delicious, Facebook and Google Bookmarks. These take you to the submission page of the service where you can fill in the title1. Digg and Reddit will show existing submissions if the link has already been submitted.

I often share links on IRC, and wondered if I could integrate that with my menu. It turns out that WeeChat has a control socket, and I could send messages by piping them to the socket. I therefore wrote a script which prompted me for a headline or excerpt using kdialog, and then sent the link to the specified channel. My menu now looks like this:

sharemenu.png

If you want to set this up yourself, download share.desktop and put it in ~/.kde/share/apps/konqueror/servicemenus. If you want the icons, download shareicons.tar.gz, extract them somewhere, and fix the paths in social.desktop2. To setup the IRC feature (assuming you're using WeeChat), download postirc.sh and save it in ~/bin/. You will need to change the commands in social.desktop depending on the servers and channels you wish to use.


  1. One shortcoming is that the title of the page is not automatically filled in. 

  2. I couldn't work out how to use relative paths, or ~. 

September GeekDinner

I attended my second GeekDinner on Monday evening. It was a fairly small occasion with about 30 people turning up at Asoka in Gardens.

Joe gave a very intriguing talk on lifestyle design. Some of the points included work less and cheat, which I didn't really agree with, but the basic idea of doing the things you love was good. Jonathan then spoke about actually doing something with your ideas, which was quite inspiring. I don't really get "big" ideas, but I'm going to try anyway.

The other Jonathan showed us Half Price Tuesdays which is an idea he's been working on. I'm helping with the alpha test and it's looking very promising. Kerry-Anne then did a fantastic slideshow karaoke prepared by Jonathan. She gave us some tips on how to survive a GeekDinner talk, but unfortunately needs to implement some of those tips herself :-P

Many thanks to Asoka for hosting us, and to Perderberg for the wine sponsorship. I hope to see more people attend next time.

Windows users finally get circular scrolling

When I first started using Linux four years ago, one of the most useful features I discovered was circular scrolling on touchpads. (For those that don't know, this allows you to scroll up and down by moving your finger in a circle.) Traditional scrolling now feels very clumsy, and I find it awkward when using a laptop which doesn't have this feature (such as those running Windows). According to the changelog for the XOrg/XFree86 Synaptics driver, this feature was added in February 2004.

I happened to come across the news today that Synaptics have added a feature called ChiralTouch Technology to the latest version of their Windows drivers. This so-called "technology" provides "the ability to scroll continuously with a circular motion." This basically means that they have finally gotten round to implementing a very useful feature which Linux users have had for over four years.

In some respects proprietary software is way behind FOSS in terms of features and usability, and this example also shows how proprietary software uses ideas which were first implemented in FOSS.

Vim syntax highlighting for irssi IRC logs

When I occasionally read [IRC][] logs saved by [irssi][], I find the lack of colouring rather annoying and find that I can't read them very quickly. I finally got round to writing a syntax highlighting plugin for [Vim][] in order to correct this. The colours could probably do with some improvement, but it's much better than before.

In case anyone else finds this useful, I have attached the plugin to this post. To use it, save [irssilog.vim][irssilog.vim] in ~/.vim/syntax/ and enter the following command to use it with the current file.

:set syntax=irssilog

If you want Vim to automatically detect the file type, add the following to ~/.vim/ftdetect/irssilog.vim1.

au BufRead,BufNewFile */irclogs*.log    set filetype=irssilog

  1. This relies on the logs being stored in the default location of ~/irclogs/

My personal backup solution

I've been using an external harddrive to store backups of my laptop for a while now. At first I manually created a set of compressed tar archives about once a month. That was a bad system though because it used a lot of space and was a mission to retrieve files from backups. I then started using pdumpfs, which can do incremental backups by hard linking files which haven't changed. The problem I found with it however was that if a file's ownership or timestamps changed it wouldn't be hard linked even if the content hadn't changed.

I therefore set out to find a better backup solution. My requirements were as follows.

  1. Incremental backups
  2. Easy to access specific files from backups
  3. Able to delete certain backups, preferably arbitrarily1
  4. Compression
  5. Encryption

I finally settled on storeBackup which supports everything except number 5. It works similarly to pdumpfs, except it stores ownership and timestamp data separately and therefore can still hard link identical files even if these change. It compresses on a per file basis, which makes it easy to access specific files (as opposed to having to find them in an archive). Old backups can be deleted arbitrarily since they are only related by hard links. I then added encryption by backing up to an encfs encrypted directory.


  1. I want to be able to backup every week, but then delete old backups so that I have one backup per month for the last year. 

CLUG Political Compass graph

A couple people on #clug were updating their Political Compass scores, which prompted me to jump on the bandwagon and do the test. I came out with the following scores.

Economic Left/Right: -4.38
Social Libertarian/Authoritarian: -2.21

I then thought that it would be interesting to compare everyone's scores on a graph, so I wrote a [Python][] [script][py] to get the scores from Spinach and a [Gnuplot][] [script][p] to plot them.

CLUG Political Compass

To add yourself to the graph, tell Spinach your score in the following format. The graph is regenerated every hour.

cocooncrash.political_compass is -4.38 / -2.21 (2008/09/14)

Downloading Google Talk logs

I used Google Apps to host mail for this domain for a while, and wanted to close down the account since I don't use it anymore. Before I did that I wanted to move all the data onto my server. Transferring the emails was fairly straightforward using [POP3][], but I couldn't find a way to download the [Google Talk][] logs. [Gmail][] handles the logs as emails, but they aren't accessible using either POP3 or [IMAP][].

I therefore wrote a [Python][] script which downloads the logs via the web interface. On [Jeremy's][] [suggestion][] I used [BeautifulSoup][] to parse the [HTML][] this time, which worked very well. The script works with both Google Apps and normal Gmail, although my account got locked twice while trying to download the 3500 logs in my account.

Routing by port number

Due to a very restrictive firewall at the CHPC, I need to run a VPN to get access to things like email, Jabber and SSH. This however degrades my web browsing experience, since that gets tunnelled as well. I therefore wanted a setup where only ports which are blocked get tunnelled through the VPN, while everything else goes out normally.

The routing part was fairly straightforward, which consists of an iptables rule to mark certain packets, and an alternate routing table for these marked packets. I first created a name for the new table by adding the following to /etc/iproute2/rt_tables.

10  vpn

I then added a default route to the new table specifying the IP address of the VPN server and the VPN interface, and a rule to use this table for packets marked by iptables.

ip route add default via 10.8.0.3 dev tun0 table vpn
ip rule add fwmark 0x1 table vpn

The following iptables rule will mark packets destined to the listed port numbers. Note that this is for packets originating from the firewall host — if you want this to apply to packets forwarded for other hosts it must be in the PREROUTING chain.

iptables -t mangle -A OUTPUT -p tcp -m multiport --dports 22,995,587,5223 -j MARK --set-mark 0x1

The actual routing worked, but packets were being sent with the wrong source IP. I therefore needed to NAT packets going out on the VPN interface (the IP address is the local IP of the VPN connection).

iptables -t nat -A POSTROUTING -o tun0 -j SNAT --to 10.8.0.4

I could then see packets going out on the VPN interface with the correct source IP as well as the replies, but it still wasn't working. I eventually discovered that rp_filter must be disabled in order for this to work.

echo 0 > /proc/sys/net/ipv4/conf/tun0/rp_filter