Reversed Entropy

mflowDet 1.3

Angel — Sun, 25 Sep 2011 03:48:38 +0000

I just updated my mflow widget to add some functionality and bug fixes. You can check it's page to check the whole changelog and download it, as I don't have automatic updates yet.

cron job to check if minecraft server is running

Angel — Sun, 25 Sep 2011 02:49:03 +0000

I wrote a little script that checks if my Minecraft server status is running, and if it's not try to start it up. I run my server on Ubuntu and I use a wrapper I found on a forum. I can't find the post now (it was on http://www.minecraftforums.com), but I will post it in case anyone want to use this solution, seems to work pretty well and has bukkit support.

My script will call the service status, check if the status is 'not running' or 'running', start it if it's not running and mail myself the results. I'm running it every 5 minutes using cron and, for now, it has waken the server 2 times in 24 hours. This is great as some friends play while I'm sleeping, so they won't wake me up in order to reset the server!

My crontab line is:

1	/5 * * * /bin/bash /home/minecraft/check.sh >> check.log

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#!/bin/sh

# Email config
mail_bin=/usr/bin/mail
mail_subject="Minecraft server"
mail_address="devnulls@gmail.com"
mail_file="$(mktemp)"

# Example for worlds="mars venus earth"
# minecraft_server contains your wrapper script file
worlds="mars"
minecraft_server="/etc/init.d/minecraft_server"

echo $(date)
echo "----------------------- MINECRAFT BARKING DAEMON -----------------------"
echo "------------------------------------------------------------------------"

check_servers(){
for w in $worlds
do
echo "Checking $w status..."
status=$($minecraft_server status $w | grep 'not running')
if [ "$status" != "${status/not running/}" ]; then
echo "$w is offline, trying to restart it..."
echo "$w is offline, trying to restart it..." >> $mail_file
$minecraft_server start $w
/usr/bin/mail -s $mail_subject $mail_address < $mail_file

else
echo "$w is online"
echo "$w is online" >> $mail_file
/usr/bin/mail -s $mail_subject $mail_address < $mail_file
fi

echo "------------------------------------------------------------------------"
done
}

# MAIN
check_servers

echo ""
echo ""

Usando los DNS dinámicos de CDmon

Angel — Sun, 26 Jun 2011 01:38:52 +0000

Llevo varios meses mudando todos mis dominios desde GoDaddy y algún otro registrador a CDmon. Su servicio de atención al cliente es muy bueno, sus precios competitivos y son una compañía nacional, que siempre es bueno.

Andaba buscando la forma de, ahora que tengo IP dinámica otra vez, poder volver siempre a mi equipo sin tener que usar servicios externos, aplicaciones funcionando constantemente y soluciones similares. Así que, a medio camino de escribir un script enorme para navegar a través del panel de administración y cambiar el registro de IP de un subdominio, he encontrado que CDmon ofrece un servicio de DNS dinámico con API.

En Mac OS (también funcionará en Linux y seguramente no sea difícil hacerlo funcionar en Windows) ha sido tan fácil como añadir un cronjob que se ejecuta cada 10 minutos, haciendo simplemente una petición a la API de CDmon que actualiza la IP.

Dejo aquí como referencia lo que hay en mi crontab, solo hay que sustituir USR por tu usuario y PWD por el MD5 de tu contraseña. Ojo, que no es el usuario con el que accedes al panel de CDmon, si no el que hayas creado para actualizar ese subdominio.

1	/10 * * * /usr/bin/curl --silent "https://dinamico.cdmon.org/onlineService.php?enctype=MD5&n=USR&p=PWD" > /dev/null

PD. Sí, voy a empezar a escribir en castellano por aquí.

Validating email addresses

Angel — Sat, 26 Jun 2010 19:30:53 +0000

Email address validation is a common issue in any language, but it's more common in those oriented to create web pages like PHP.

The standar for email address naming is the RFC 2882, and it's long, long and complicated. Too complicated to fit in a regular expression, so I don't recommend anybody to try a regex implementation of the full standar, it's simply impossible.

The best approach to solve this particular problem is to write a small and understandable regular expression that accepts some invalid email addresses but catches all the valid ones. Is better to let some inexistent emails than don't let an user register with his completely valid and working email.

Double check: one using regex and once passed validate the email address on the only way that you'll now that is valid for sure: send an email containing an activation link.

Since we are going to double check is OK to trust the client and do the first validation using JavaScript. Once passed we'll send an email to that address on the server side, and it won't be confirmed until the activation link is clicked, so as I said before: is OK if you get some invalid email address.

Keeping it simple: I only check for something followed for a @ then another something with a dot and a final something (with any characters and even more dots!).

/((.+)@(.+)\.(.+))/

The above regular expression will:

Match

user@mail.com
user+mail@mail.com
user+mail@mail.co.uk
mail@mail.commm
user/mail@gmail.com

Not Match

user+mail@.com
@mail.com
user@mail

As said, it will match invalid email addresses, just confirm them sending an email, the rest is just meaningless effort to solve a problem that cannot be solved using regular expressions.

Cookies, cURL and PHP without a jar

Angel — Mon, 21 Jun 2010 23:11:46 +0000

cURL is one of the best ways of implementing the client side of a RESTful service with PHP, is also really handy to take some data from other websites and do with it whatever you want.

Taking this data can be a problem when you need to autenticate on the third party website using cookies. Rest supports sending and retrieving them, but all the tutorials I've found use txt files to cache those cookies for being able to send them back to the server.

I don't like this approach, so let's see how to grab and store them on-the-fly using a simple regular expresion. First, let's setup a simple authentication page in PHP.

We're going to do at least two connections to the target server, the first one will send the password to the form and grab the cookie, the second one will call again the same server but this time we will send the cookie along our petitions, so we can navigate through private pages like we were a normal user.

I think that the first file (set.php) don't need commenting, is pretty basic and it only show debug text and sets the cookies/sessions. It would be something like this:

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function pre($data){
echo "

"; print_r($data); echo "<\/pre>";

}

 



session_start();

setcookie("TestCookie1", rand(0, time()));

setcookie("TestCookie2", rand(0, time()), time()+3600);  /* expire in 1 hour */

setcookie("TestCookie3", rand(0, time()), time()+3600, "/~rasmus/", ".example.com", 1);



if(isset($_REQUEST['password']) OR isset($_SESSION['username'])){

    if(isset($_REQUEST['password']) &amp;&amp; $_REQUEST['password'] == "Island"){

        $_SESSION['username'] = "John";

    }



    if(isset($_SESSION['username']) &amp;&amp; isset($_REQUEST['password'])){

        echo "You're logged in as ".$_SESSION['username']." (Private, using cURL with POST)";

    } elseif(isset($_SESSION['username']) &amp;&amp; !isset($_REQUEST['password'])) {

        echo "You're now logged in as ".$_SESSION['username']." (Private, using cURL with Cookies)";

    } else {

        echo "(Public Access - No auth received)";

    }

}



if(isset($_COOKIE['PHPSESSID'])){

    pre("Here are the cookies sent:");

    pre($_COOKIE);

}

The following code is the interesting part, here you can see how to do the cURL connection, grab the cookies and prepare them to be sent back with the next request.

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/* A little function to trace the results when
* needed, is not used on the functionality
*/
function pre($data){
echo "

"; print_r($data); echo "<\/pre>";

}

 



/* We open the first cURL connection against an authentication form

 * using only a valid password,

 */

$webservice = "http://www.reversedentropy.net/scripts/cookie-set.php";

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, $webservice);

curl_setopt($ch, CURLOPT_HEADER, 1);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

curl_setopt($ch, CURLOPT_POST, 1);

 curl_setopt($ch, CURLOPT_POSTFIELDS, "password=Island");



 // Execute the request

$request = curl_exec($ch);



/* We need to use regex to catch the cookies from the received

 * header and match them to a variable

 */

preg_match_all("/Set-Cookie: (.*)/", $request, $cookies);



/* Let's show the header to see which cookies did we receive.

 *

 */

pre($request);



/* Now that we have an array with all the cookies we need to parse

 * them in order to be able to send them back in the second request

 * against the server, so first of all we'll create a new variable

 * to store them.

 */

$jar = "";

foreach($cookies[1] as $value){

    /* This is a little tricky, as the cookies may have a path or expire

     * time set that we don't need at all but can interfere with the parse

     * so first we'll catch the cookie name (as $ckey)

     */

    $c = explode("=", $value);

    $ckey = $c[0];



    /* Then we have two possible scenarios: no more parameters apart from the

     * cookie and it's value, and a path, lifetime... If there's a ";" on the

     * string there's another parameter, so we explode again and catch only

     * the cookie value, forgetting about the rest. If there's no ";" we catch

     * directly the value and set it to $cval.

     */

    if($d = explode(";", $c[1])){

        $cval = $d[0];

    } else {

        $cval = $c[1];

    }



    /* The string containing all cookies should be in key=value;key=value[..] format

     * so we'll first of all remove all whitespaces, then urlencode the value and

     * add it to the $jar string that we created before

     */

    $cval = trim(preg_replace('/\s+/', '', $cval));

    $cval = urlencode($cval);



    $jar .= $ckey."=".$cval."; ";

}



/* Now we'll output the cookie string as reference and make another

 * call to the same server, thsi time without posting any password

 * We'll show the response as we want to see the logged message

 */

pre("Cookies inside the virtual jar:");

pre($jar);

By now we got a virtual cookie jar processed, we have all the cookies (the test script is setting a PHPSESSID and three test cookies without any relevant data) and we can store them on a database, on a file or work directly with them on the same script. So let's try it, we are going now to call the same server, but we're not going to send the password, we'll send the cookie.

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curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POSTFIELDS, false);
curl_setopt($ch, CURLOPT_COOKIE, $jar);
$request = curl_exec($ch);

/* And that's it, we're now logging against this server using cookies
* on-the-fly, without storing them.
*/
pre($request);
curl_close($ch);

And that's it, easy, right? You can see a little demo of this script working here, or download a zip containing the example source code.

mflowDet: mflow widget for WordPress

Angel — Wed, 16 Jun 2010 22:19:36 +0000

View download links and changelog info.

Do you know what is mflow? As many people said, in few words, is the son of Twitter and iTunes. Right now it's only available on the UK, but probably will spread across Europe soon. You can read more and try it on it's website.

I just coded a little widget for WordPress that grabs the last flow from your mflow web profile (http://my.mflow.com/username) and adds it to your sidebar.

This plugin used to work with an HTML parser, now it just uses the mflow API. Still missing a lot of things but it gets the job done!

The installation is simple: drop the mflowdet folder into your plugins folder and add the widget on the Appearance section of your WordPress admin panel, there you can change the username.

Changelog

1.3 (Download)

Fixed date
Fixed user URL (mflow changed their url scheme)
Added option to show more than 1 flows (up to 10)

1.2 (Download)

PHP4+ Compatibility added
Removed PHP Simple HTML DOM Parser
Uses the mflow API to grab the data
Cleaner code
Pre custom HTML built
Plugin cache has been removed as I am grabbing the data from a web service. I'll add it again if needed.

1.1 (Download)

Removed classes and objects from the plugin.
Changed the data array to made it more understandable
Minor bug fixes

1.0 (Not available)

First version

Requeriments

PHP4+
WordPress 2.7.x or higher
PHP Simple HTML DOM Parser (included)

Roadmap

Add an option to output custom HTML
Add error handling for the web service and the plugin itself
Upload to wordpress.org and have automatic updates

Known Issues

Fails when the last flow is an album (only occurs when buying and flowing the whole album)