inet_ntoa and inet_aton in Ruby

Posted by Dan Sosedoff on April 16, 2009

Here is two small functions to convert IP addresses from string representation to integer and vice versa.

def inet_aton(ip)
    ip.split(/\./).map{|c| c.to_i}.pack("C*").unpack("N").first
end
 
def inet_ntoa(n)
    [n].pack("N").unpack("C*").join "."
end

Useless filesystem over MySQL

Posted by Dan Sosedoff on April 06, 2009

Here is a completely useless filesystem based on MySQL database storage – mysqlfuse, implemented with Fuse.
I didnt find any way how i can use it, but meanwhile, this fs working. Not perfect of course, in that case its not maintained for a long time. Doesnt support information about free drive space, so any filemanager keeps saying ‘Error: No space left on device’. Such case making it more useless.

It`s really easy to set it up.

First, we need to install developer headers for fuse:

$ apt-get install libfuse-dev

Next, getting sources (32bit only, not working in 64bit):

$ wget http://voxel.dl.sourceforge.net/sourceforge/mysqlfs/mysqlfs-0.4.0-rc1.tar.bz2

Unpack it, and compile:

$ tar -xjvf mysqlfs-0.4.0-rc1.tar.bz2
$ cd mysqlfs-0.4.0-rc1
$ ./configure && make && make install

Next, we need to setup the database

CREATE DATABASE mysqlfs;
GRANT SELECT, INSERT, UPDATE, DELETE ON mysqlfs.* TO mysqlfs@"%" IDENTIFIED BY 'password';
FLUSH PRIVILEGES;

And create database schema. SQL file located in root folder of the sources

$ mysql -uroot -p mysqlfs < schema.sql

And finally, mount filesystem to some folder:

$ mysqlfs -ohost=MYSQLHOST -ouser=MYSQLUSER -opassword=MYSQLPASS -odatabase=mysqlfs MOUNT_DIR

Now, its gonna be working. To use automatic configuration parameters you can create section [mysqlfs] in your mysql configuration file (my.cnf)

Parameters:

-ohost=
    MySQL server host

  -ouser=
    MySQL username

  -opassword=

    MySQL password

  -odatabase=
    MySQL database name

That`s it. Anyway, using FUSE there is a way to create so weird filesystems proxy. For example, there is SQLite over FUSE. And it is too old. Next time i`ll write about Amazon S3 over FUSE projects.

Simple file uploader to Amazon S3 Service 1

Posted by Dan Sosedoff on March 22, 2009

For a long time i was thinking that Amazon`s Simple Storage Service (S3) is very complicated thing. But, it was before i tried it. Couple days ago, i got account to S3 and started exploring API`s and architecture. Now i see how stupid i was :) It`s really easy to handle all operations with files and buckets. Pricing also comfortable.

Welcome to cloud computing! :) I started using it with Ruby. Regular gem and docs can be found at http://amazon.rubyforge.org/

So, the first useful tool i decided to created – simple uploader of local files to amazons server.
First, we need to create bucket and make it public:

Bucket.create('NAME_HERE',:access => :public_read)

Here`s the client ruby script:

#!/usr/bin/ruby
 
require 'rubygems'
require 'aws/s3'
 
include AWS::S3
 
$s3_bucket = "BUCKET_NAME"
$s3_key = "API_KEY"
$s3_secret = "API_SECRET"
 
def s3_store(localfile)
	if File.exists?(localfile) &amp;&amp; File.readable?(localfile)
		puts "Uploading file [#{localfile}]. Size: #{File.size(localfile)} bytes."
		name = File.basename(localfile)
		Base.establish_connection!(:access_key_id => $s3_key, :secret_access_key => $s3_secret)
		S3Object.store(name, open(localfile), $s3_bucket, :access => :public_read)
		puts "Download link: http://s3.amazonaws.com/#{$s3_bucket}/#{name}"
	else
		puts "File not exists or not accessible. Please check file and try again!"
	end
end
 
path = ARGV[0]
if !path
	"Please specify the file to upload."
else
	s3_store(path)
end

Download script: http://files.sosedoff.com/036cfedd/

BTW, I found cool firefox add-on to manage S3 objects/files. It`s pretty easy.
Link to extension – http://www.s3fox.net
Screenshot:

Scaling images with ImageMagick and PHP 1

Posted by Dan Sosedoff on March 20, 2009

Here is php version of ruby class that i made a long time ago. The same functionality and results.

<?
class ImageScale {
 
	private function changeGeometry($sz,$value) {
		if ($sz['width'] > $sz['height']) { // horizontal image
			$newsz['width'] = $value;
			$newsz['height'] = ceil(($newsz['width'] * $sz['height']) / $sz['width']);
		}
		else { // vertical image
			$newsz['height'] = $value;
			$newsz['width'] = ceil(($newsz['height'] * $sz['width']) / $sz['height']);
		}
		return $newsz;	
	}
 
	private function changeGeometry2($sz,$value) {
		$newsz['width'] = $value;
		$newsz['height'] = ceil(($newsz['width'] * $sz['height']) / $sz['width']);
		return $newsz;
	}
 
	/**
	 * 	Make thumbnail of specified maximum side size
	 */
	public function processThumb($source_path, $dest_path, $sidesize, $quality=85, $scale_method=1) {
		if (file_exists($source_path) && is_readable($source_path)) {
			$image = new Imagick($source_path);
 
			$geometry = $image->getImageGeometry(); // ['width', 'height']
			if ($geometry['width'] > $sidesize) {
				if ($scale_method == 1) $geometry = $this->changeGeometry($geometry,$sidesize);
				if ($scale_method == 2) $geometry = $this->changeGeometry2($geometry,$sidesize);
			}
			$image->cropThumbnailImage($geometry['width'],$geometry['height']);
			$image->setCompression(Imagick::COMPRESSION_JPEG);
			$image->setCompressionQuality($quality);
			return $image->writeImage($dest_path);
		}
		return false;
	}	
 
	/**
	 * 	Make square thumbnail
	 */
	public function processRectThumb($source_path, $dest_path, $size=150, $quality=85) {
		if (file_exists($source_path) && is_readable($source_path)) {
			$image = new Imagick($source_path);
 
			if ($image) {
				$image->cropThumbnailImage($size,$size);
				$image->setCompression(Imagick::COMPRESSION_JPEG);
				$image->setCompressionQuality($quality);
				return $image->writeImage($dest_path);
			}
		}
		return false;
	}
}
?>

Download file – http://files.sosedoff.com/1167c8db/

Init.d nginx script for Debian and RHEL systems

Posted by Dan Sosedoff on March 15, 2009

Here is general init.d nginx script that working on Debian and RHEL/CentOS systems. It`s set to default configuration with main path to nginx = /usr/local/nginx

#!/bin/sh
#
# Init file for nginx
#
# chkconfig: 2345 55 25
# description: Nginx web server
#
# processname: nginx
# config: /usr/local/nginx/nginx.conf
# pidfile: /usr/local/nginx/nginx.pid
 
# Description: Startup script for nginx webserver on Debian. Place in /etc/init.d and
# run 'sudo update-rc.d nginx defaults', or use the appropriate command on your
# distro. For CentOS/Redhat run: '/sbin/chkconfig --add nginx'
#
# Author: Ryan Norbauer <ryan.norbauer@gmail.com>
# Modified: Geoffrey Grosenbach http://topfunky.com
# Modified: David Krmpotic http://davidhq.com
# Modified: Vishnu Gopal http://vish.in
# Modified: Dan Sosedov <dan.sosedoff@gmail.com>
 
set -e
 
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DESC="nginx daemon"
NAME=nginx
DAEMON=/usr/local/nginx/sbin/$NAME
CONFIGFILE=/usr/local/nginx/conf/nginx.conf
PIDFILE=/usr/local/nginx/logs/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME
 
# Gracefully exit if the package has been removed.
test -x $DAEMON || exit 0
 
d_start() {
  $DAEMON -c $CONFIGFILE || echo -en "\n already running"
}
 
d_stop() {
  kill -QUIT `cat $PIDFILE` || echo -en "\n not running"
}
 
d_reload() {
  kill -HUP `cat $PIDFILE` || echo -en "\n can't reload"
}
 
case "$1" in
  start)
    echo -n "Starting $DESC: $NAME"
    d_start
        echo "."
  ;;
  stop)
    echo -n "Stopping $DESC: $NAME"
    d_stop
        echo "."
  ;;
  reload)
    echo -n "Reloading $DESC configuration..."
    d_reload
        echo "."
  ;;
  restart)
    echo -n "Restarting $DESC: $NAME"
    d_stop
    # One second might not be time enough for a daemon to stop,
    # if this happens, d_start will fail (and dpkg will break if
    # the package is being upgraded). Change the timeout if needed
    # be, or change d_stop to have start-stop-daemon use --retry.
    # Notice that using --retry slows down the shutdown process somewhat.
    sleep 1
    d_start
    echo "."
  ;;
  *)
    echo "Usage: $SCRIPTNAME {start|stop|restart|reload}" >&2
    exit 3
  ;;
esac
 
exit 0

Usage:

$ sudo /etc/init.d/nginx (start|stop|restart|reload)

You also can download it – http://files.sosedoff.com/e570e29f/

Scaling images with RMagick

Posted by Dan Sosedoff on March 14, 2009

Simple class that providing scaling (rectangle and thumbnails) for images using RMagick and Ruby.
Code:

class ImageScale
    def change_geometry(sz,value)
        w = sz[0] ; h = sz[1]
            if w > h
                sz[0] = value
                sz[1] = ((value * h) / w).floor
            else
                sz[1] = value
                sz[0] = ((value * w) / h).floor
            end
            return sz
    end
 
    def make_rect(file_in,file_out, width, quality=85, sharp=false) 
        if FileTest.exists?(file_in)
            begin
                img = Magick::Image.read(file_in).first
                img.crop_resized!(width,width, Magick::CenterGravity)
                img = img.sharpen(0.5, 0.5) if sharp
                img.write(file_out) { self.quality = quality }
                return true if FileTest.exists?(file_out)
            rescue Magick::ImageMagickError
                return false
            end
        end
        return false
    end
 
    def make_thumb(file_in,file_out, width_to, quality=85, sharp=false) 
        if FileTest.exists?(file_in)
            begin
                img = Magick::Image.read(file_in).first
                info = [img.columns,img.rows]
                sz = change_geometry(info, width_to)
                img = img.resize(sz[0],sz[1])
                img = img.sharpen(0.5, 0.5) if sharp
                img.write(file_out) { self.quality = quality }
                return true if FileTest.exists?(file_out)
            rescue Magick::ImageMagickError
                return false
            end
        end
        return false
    end
end

Ok, let`s see how this class working. For example, we have source image:
Source Image

Function ImageScale.make_rect(src,dest,64) will produce such image:
Rectangle Image

Function ImageScale.make_thumb(src,dest,200) will produce thumbnail:
Thumbnail Image

There is optional parameter sharp to use sharping. Optional parameter quality is set to 85% compression value.

Identify www bots and mobile devices

Posted by Dan Sosedoff on March 12, 2009

Need to identify web crawlers and mobile devices with your web-app ? Here is the list of couple regular expressions you can use (most common values):

Mobile Devices:

/(blackberry|motorokr|motorola|sony|windows ce|240x320|176x220|palm|mobile|iphone|ipod|symbian|nokia|samsung|midp)/i

Web Spyders:

/(google|yahoo|baidu|bot|webalta|archiver|crawler|spyder)/i

Connecting to wifi with specified wep key index

Posted by Dan Sosedoff on March 09, 2009

Since i got trouble while connecting to wireless network with given parameters in linux, i tried a lot of ways to get my internet working.

So, the problem is: Windows Network manager have special option – Key index. The index is transmitted with the encrypted message. The receiver then looks-up the key corresponding to the transmitted index and uses it to decrypt the message. But linux (ubuntu) network managers i`ve tried have no key index field, so there is no way to set it up properly with gui. Connection won`t work if index value set to incorrect value.

After giving up to find any useful gui program i wrote small shell script only for one network (because i have no access to router and no chance to improve some security settings):

#!/bin/bash
 
# settings
interface="ath0" # wireless interface, default to wlan0
essid="NETWORK_NAME_HERE"
key="YOUR_KEY_HERE"
index="4" # can be [1..4]
 
# check permission
if [ "$(id -u)" != "0" ]; then
   echo "Run this script under root" 1>&2
   exit 1
fi
 
# show information
echo "Settings:"
echo "-> Interface: $interface"
echo "-> Wifi ESSID: $essid"
echo "-> Key: $key"
echo "-> Key Index: $index"
 
# perform association
ifconfig $interface down
iwconfig $interface essid $essid
iwconfig $interface key $key [$index]
iwconfig $interface key [$index]
ifconfig $interface up
dhclient $interface

Download shell script – http://files.sosedoff.com/9591756c/

Check root user permissions in bash scripts

Posted by Dan Sosedoff on March 09, 2009

For example, in your bash shell script you`re going to use some root-specific commands like network operations, mounting devices and so on. There are couple easy ways to check if your script is executing under root privileges.

#!/bin/bash
# ...
if [ "$(id -u)" != "0" ]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi
# ...

Another way: use EUID. When user account created a user ID is assigned to each user. Bash shell stores the user ID in $UID variable. Your effective user ID is stored in $EUID variable.

#!/bin/bash
# ...
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi
# ...

Fetching album covers from Last.Fm API 3

Posted by Dan Sosedoff on February 15, 2009

As previous post was about fetching covers media from Amazon Web Services, this post will be about fetching covers from popular music site – Last.fm. API documentation page

#!/usr/bin/ruby
 
require 'rubygems'
require 'net/http'
require 'cgi'
require 'xmlsimple'
 
# key from API documentation
$lastfm_key = "b25b959554ed76058ac220b7b2e0a026" 
$lastfm_host = "ws.audioscrobbler.com"
 
def fetch_cover(artist, album)
	artist = CGI.escape(artist)
	album = CGI.escape(album)
 
	path = "/2.0/?method=album.getinfo&api_key=#{$lastfm_key}&artist=#{artist}&album=#{album}"
	data = Net::HTTP.get($lastfm_host, path)
	xml = XmlSimple.xml_in(data)
	if xml['status'] == 'ok' then
		album = xml['album'][0]
 
		cover = {
			:small => album['image'][1]['content'],
			:medium => album['image'][2]['content'],
			:big => album['image'][3]['content']
		}
 
		return cover
	end
 
	return nil
end
 
puts fetch_cover('Nickelback', 'Dark Horse').inspect

Download ruby script