Tactical Nuclear Strike

Wifi signal strength in oh-my-zsh

Sat, 29 Apr 2017 00:00:00 +0000

I recently switched theme in oh-my-zsh to powerlevel9k while the docs cover most things the wifi signal example was Linux only so I modified it to work on MacOS (only tested on Sierra) and modified to use nerd-fonts as its not the same unicode as in the docs example.

zsh_wifi_signal(){
    local signal=$(/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | grep CtlRSSI | awk '{print $2}')
    local color='%F{yellow}'
    [[ $signal -gt -60 ]] && color='%F{green}'
    [[ $signal -lt -70 ]] && color='%F{red}'
    echo -n "%{$color%}\uf424 %{%f%}"
}

POWERLEVEL9K_CUSTOM_WIFI_SIGNAL="zsh_wifi_signal"
POWERLEVEL9K_CUSTOM_WIFI_SIGNAL_BACKGROUND="black"

POWERLEVEL9K_RIGHT_PROMPT_ELEMENTS=(status custom_wifi_signal load disk_usage battery)

POWERLEVEL9K_MODE='nerdfont-complete'

So with that in my .zshrc my prompt looks like this right now

Nodeunit and Proxies

Sat, 30 Apr 2016 00:00:00 +0000

With ES6 in javascript we get a lot of cool things to make it a proper programming language, fun stuff like Proxy.

Recently I found a nice use for Proxies when writing tests however the nodeunit runner doesn’t support the –harmony-proxies parameter a small runner was created to allow us to run tests with working Proxy support. Just create a small script that looks something like this.

const reporter = require('nodeunit').reporters.minimal;
let args = process.argv;
args.splice(0,2);
reporter.run(args);

And invoke it using:
node --harmony-proxies runtests.js $(find ./tests -name \*.js)

Yubikey & KeePass cross platform

Sat, 18 Jul 2015 00:00:00 +0000

A while back i got a Yubikey Neo and a Neo-n they are cool little devices that can work as the second part of a 2 factor authentication. The Neo apart from usb also supports Nfc so it can be used with most modern Android phones. So here’s a short summary of how to get it all working. To get everything to work you need to install the KeeChallenge plugin in KeePass, I used the latest version (2.29) when setting everything up. The trick is to put the password file on something shared that everything can read usb stick, Dropbox or similar.

KeePass on windows

For windows follow this guide. Don’t forget to copy the files from the YubiKey-Personalization release.

KeePass on OSX

On OSX the use following guide. A bit more hands on work but just follow the steps. Currently it seems like mono 4.0.2 doesn’t work so go with 4.0.1.

KeePass on Android

On android you need the Keepass2Android Password Safe and YubiChallenge and a phone that supports Nfc, most modern Android phones do.

iOS

Nope, return in a couple of years when iOS has working nfc support

Home monitoring and sensors

Wed, 08 Jul 2015 00:00:00 +0000

I like dashboards

So I built one using InfluxDB, Grafana, Nginx, Tellstick Net and a bunch of scripts. Here’s a breakdown of the parts and what feeds them.

Temperatures

At home i have a Tellstick Net and a bunch of remotecontrolled power switches connected to this i also have a bunch of temperature sensors (this model) places around the house, outside and in my shed.

Logging to InfluxDB

Data is fed into InfluxDB using a couple of different scripts.

Temperatures are read from Telldus Live using a modified version of their tdtool.py script every 10 minutes
To log status for my home server running ubuntu I modified my status script, this is logged every 5 minutes.
Ping & packet loss is logged with a simple ping script, right now it only pings googles public dns but is should be extended to ping multiple things (isp dns server etc) currently this script runs every minute

Improvements

I plan to add more fun sensors that work with Tellstick, things like rain and wind sensors. Something that logs how bright the sun is would be cool to. At some point when I have more info it will be fun to do some ‘big data’ stuff using the data set I have, right now it’s been running for about 6 months so next year it’s possible to graph current vs last year for many values.

AutoMapper & AutoFac

Wed, 16 Jul 2014 00:00:00 +0000

Prelude

So I tend to develop things in the way of

Make it work
Make it pretty

Make it work

So when using AutoMapper after step one I ended up with something like this

.ForMember(d => d.SomeSource, 
     o => o.MapFrom(
          s => new Serializer().Deserialize<SomeViewModel>(s.Serialized)))

Some background, for the destination SomeSource I needed to Deserialize the value as it was currently stored as Json in my database.

Make it pretty

While it works it looks rather horrible, so I started looking into something that allowed me to get a ISerializer from AutoFac (my IoC of choice) instead.

So, first I added a custom ValueResolver that looked like this

public class SomeViewModelResolver 
    : ValueResolver<OrderRow, ScheduleViewModel>
    {
        private readonly ISerializer _serializer;

        public ScheduleViewModelResolver(ISerializer serializer)
        {
            _serializer = serializer;
        }

        protected override SomeViewModel ResolveCore(Source source)
        {
            return _serializer.Deserialize<SomeViewModel>(source.Serialized);
        }
    }

Next was to connect AutoMapper with AutoFac and to register the ValueResolver:

// Register my new valueresolver
builder.RegisterType<SomeViewModelResolver>();

// Connect AutoMapper to AutoFac
Mapper.Initialize(x => x.ConstructServicesUsing(container.Resolve));

Once that is done the last thing to change is to modify the ForMember call to use the new ValueResolver instead

.ForMember(d => d.SomeSource, o => o.ResolveUsing<SomeViewModelResolver>())

Looks a lot cleaner and follows the flow that you would expect when using a IoC container.

Bonus

If you don’t want to have calls to the static Mapper.Map<> all over your code, it is possible to register the IMappingEngine in AutoMapper in you IoC container and have that as an dependency for you class too. For AutoFac the registration looks like this

builder.Register(c => Mapper.Engine).As<IMappingEngine>().SingleInstance();

The important thing is to register it as a singelton. Once that is done just add IMappingEngine mappingEngine to the constructors of those classes that use AutomMapper.

Recent changes

Mon, 09 Dec 2013 00:00:00 +0000

So I’ve made some (mostly) under the hood changes to this blog. Lets start with the visible part I’ve dropped the blog part from the domain, the redirect is permanent but it might be a good idea to update your rss feed.

The fun parts are that the blog has moved from wordpress to using jekyll and is hosted on github from this repository. Migrating to jekyll was rather simple, there’s plugins that support conversion from a wordpress backup xml file to jekylls structure. Since I liked the theme (decode) used on the wordpress site I ‘ported’ it to jekyll, or well cherry picked some parts and removed most things that I didn’t need. Since I also moved the blog up from blog. to the top level I had to support the old links too, that is done using a nginx instance that does a redirect (301, permanent) from blog.* to the top level with the path intact.

A big bonus with jekyll is that I can write my posts in markdown and they are stored as simple text, no weird database or anything.

When I moved of one.com I lost my mail account that was connected to the domain, and since google apps doesn’t accept any new accounts for free anymore I looked around for an alternative that could work. While outlook.com does offer custom domain hosting if looked around a bit more and found zoho they offer a bit less space per account than google but has pop3/imap access and overall as fast as gmail.

Getting DOM element as an Image

Wed, 20 Nov 2013 00:00:00 +0000

So I recently needed to create a image from a part of a webpage (html) after a short googling I found a nice library, html2canvas, that can render a part of the dom as a canvas element, complete with all css properties. So that's a good start but I needed some way of making the image downloadable too. Turns out the canvas element has a function called toDataURL that returns the rendered content of the canvas as a data-url. The url can then be used with a <a> tag to create a download link. So the complete example looks something like this.

html2canvas($("#toclone"), {
    onrendered: function (canvas) {
        var $a = $("<a download=\"file.png\" href=\"" + canvas.toDataURL() + "\">download</a>");
        $("#somecontainer").append($a);
    }
});

This works fine in Chrome & Firefox whoever not in Internet Explorer, in IE a small hack is needed. Due to 'security' reasons IE doesn't allow data urls in <a> tags so instead you need to decode the data from the canvas and create a blob object that can be passed to the window.navigator.msSaveOrOpenBlob function.

var isIe = function() {
    var trident = !!navigator.userAgent.match(/Trident\/7.0/);
    var net = !!navigator.userAgent.match(/.NET4.0E/);
    var ie11 = trident && net;
    var iEold = (navigator.userAgent.match(/MSIE/i) ? true : false);
    return ie11 || iEold;
};

var workInHorribleIE = function(canvas, filename) {
    var image = canvas.toDataURL();
    image = image.substring(22); // remove data stuff
    var byteString = atob(image);
    var buffer = new ArrayBuffer(byteString.length);
    var intArray = new Uint8Array(buffer);

    for (var i = 0; i < byteString.length; i++) {
        intArray[i] = byteString.charCodeAt(i);
    }

    var blob = new Blob([buffer], { type: "image/png" });
    window.navigator.msSaveOrOpenBlob(blob, filename +".png");
};

html2canvas($("#cctree"), {
    onrendered: function (canvas) {
        var $a;
        if (isIe()) {
            $a = $("<a>download</a>").on("click", function () {
                workInHorribleIE(canvas, "file");
            });
        } else {
            $a = $("<a download=\"file.png\" href=\"" + canvas.toDataURL() + "\">download</a>");
        }
        $("table", $cntnt).parent().append($a);
    }
});

Guess there's better ways to detect if IE is present and most of the data-url to blob stuff should be replaced with a toBlob call once it's supported.

Making sure resource files are kept in sync

Thu, 31 Oct 2013 00:00:00 +0000

Lets assume you have a site that uses resource files to handle translations, in that case you might need a way to make sure that everything is kept in sync and translated. One way of solving this with tests, that way it can be checked during commits & builds. Since resource files are loaded based on the CurrentUICulture the test needs a way to swap culture during it's run. So here's a small class that does just that (from Stackoverflow, lost the link tho).

public class SwitchCultureContext : IDisposable
{
    private CultureInfo previousCultureInfo { get; set; }

    public SwitchCultureContext(CultureInfo temporaryCulture)
    {
        previousCultureInfo 
          = Thread.CurrentThread.CurrentUICulture;
        Thread.CurrentThread.CurrentUICulture
          = temporaryCulture;
    }

    public SwitchCultureContext(string code) 
        : this(new CultureInfo(code)) { }

    public void Dispose()
    {
        Thread.CurrentThread.CurrentUICulture 
         = previousCultureInfo;
    }
}

Basically use it inside a using() {} statement to temporarily run with a different culture. So in my case I have a resource file called Strings that is the baseline I use during development, I also have one that is for translation (using the ta-IN culture) that has all texts as placeholders to allow for them to be easily identified. So my test will read all items in by baseline and then compare it to everything from the translation. If something is missing in the translation file then the value from the baseline file will be used instead. Because I have placeholders in my translation file I can simply look at the value from the file and compare it to the value form the baseline file in no case should the be the same. So the 'litte' test

[Test]
public void AllPropertiesOnBaseShouldBeOnTranslation()
{
    var baseLine = new Dictionary&lt;string, string&gt;();
    var translated = new Dictionary&lt;string, string&gt;();

    var props = typeof (Strings).
        GetProperties(BindingFlags.Public | BindingFlags.Static).
        Where(p =&gt; p.PropertyType == typeof(string)).ToArray();

    foreach (var propertyInfo in props)
    {
        var info = typeof(Strings).GetProperty(propertyInfo.Name,
             BindingFlags.Public | BindingFlags.Static);
        var value = info.GetValue(null) as string;

        baseLine.Add(propertyInfo.Name, value);
    }

    using (new SwitchCultureContext("ta-IN"))
    {
        var type = typeof (Strings);
        foreach (var baseProperty in props)
        {
            var info = type.GetProperty(baseProperty.Name,
                 BindingFlags.Public | BindingFlags.Static);
            var value = info.GetValue(null) as string;

            translated.Add(baseProperty.Name, value);
        }
    }

    bool pass = true;
    foreach (var item in baseLine)
    {
        var t = translated[item.Key];
        if (item.Value == t)
        {
            pass = false;
            Debug.WriteLine(item.Key + " not translated!");
        }
    }

    Assert.That(pass, Is.True, 
        "Translation resource file is not in sync!");
}

So if the test fails it will have outputted which keys that haven't been translated. In this case my resource files only contain strings so I ignore all other properties.

Introducing frankie

Wed, 02 Oct 2013 00:00:00 +0000

For the last couple of days i've been working on a c++ version of the Sinatra web application framework, last night at Demo Dag Malmö i did a small demo of it so i might as well do a little write up too. So a "hello world" will look like this:

module(Hello, {
  Get("/", [](Context){
    return "Hello world!";
  });
});

In this example we'll listen for requests on / and return the string "Hello world!". The syntax is inspired by Nancy. Currently it supports Get request and can decode parameters if present. There's also a rough support for returning (html) files and for unknown routes a 404 will be returned. To return the file index.html when a client requests /.

module(Static, {
  Get("/", [](Context) {
    return StaticResponse("index.html");
  });
});

Most of the syntax is still in it's infancy, so it may very well change based on input and the never-ending quest to type less. For now it's self hosted using Boost.Asio but at some point it would be nice to be able to host it under nginx/apache via some kind of module. So to start any of the examples you simple call the run method with a port number that it should listen on.

int main() {
  frankie::run(9090);
  return 0;
}

Testing is done using the framework bandit, which is also a bit of inspiration for the project. Frankie is up on github, for now I'm using issues in the repository to track stuff that needs to be done. Feel free to point and laugh and help me make it better. To build it you'll need boost installed and clang, at this point it's only tested on OSX 10.8 with clang 5.0 (llvm 3.3).

Starting rails & booting a Raspberry Pi to browser

Mon, 11 Mar 2013 00:00:00 +0000

So I got a Raspberry Pi at home that I use as a dashboard, it shows me all family calendars, train status for my stop etc. To get it to work as good as possible I made the following tweaks to my installation. To keep the screen allways on & auto start midori

$ sudo nano /etc/lightdm/lightdm.conf
# add the following lines to the [SeatDefaults] section
# don't sleep the screen
xserver-command=X -s 0 dpms

$ sudo nano /etc/xdg/lxsession/LXDE/autostart
# comment everything and add the following lines
@xset s off
@xset -dpms
@xset s noblank
@midori

from http://www.niteoweb.com/blog/raspberry-pi-boot-to-browser Unclutter To hide the mouse pointer when it's not used install unclutter, sudo apt-get install unclutter Script to autostart rails on startup

#! /bin/sh
### BEGIN INIT INFO
# Provides:          rails
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start a Rails instance
# Description:       Do the simplest thing possible in keeping with
#             upstart to spin up a single Rails instance.
### END INIT INFO

# Author: Sam Pointer & Fredrik Leijon
#
# Do NOT "set -e"

PATH=/sbin:/usr/sbin:/bin:/usr/bin:/home/pi/.rvm/bin
USER="pi"
PORT=3000
RAILS_ROOT="/home/pi/path_to_app"
COMMAND="rails s -d"
DESCRIPTION="Rails instance"
RVM_PROFILE="/home/pi/.rvm/environments/default"

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
. /lib/lsb/init-functions

#
# Function that starts the daemon/service
#
do_start()
{
    # Return
    #   0 if daemon has been started
    #   1 if daemon was already running
    #   2 if daemon could not be started
    su -c "source $RVM_PROFILE && cd $RAILS_ROOT && $COMMAND" $USER
}

case "$1" in
  start)
        [ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESCRIPTION"
        do_start
        case "$?" in
                0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
                2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
        esac
        ;;
esac

from http://blog.sam-pointer.com/2011/03/24/starting-a-rails-instance-automatically-on-boot-on-ubuntu-server.html, slightly modified to support rvm. Script is also available here as a gist.