Render Markdown/GFM Documents online using the GitHub v3 API

simple code snipped to convert markdown to html, public github api

Sometimes, you need to render parts of your Markdown documents – e.g. README.md or CHANGES.md – as html to embed it into your application, documentation or project website. There are a several markdown or especially GFM (GitHub Flavored Markdown) libraries are out there, but they require an additional setup and have to be maintained.

The simple Way#

Thanks to GitHub, there is a public API available which allows you to render your documents by the GitHub webservices.

PHP Client#

/**
 * Render Markdown content using the GitHub v3 Markdown API
 * @see https://developer.github.com/v3/markdown/
 * @source https://andidittrich.de/2016/05/render-markdown-gfm-documents-online-using-the-github-v3-api
 * @license: MIT
 * @return string(html)
 */
function renderGFM($text, $repositoryContext = null){

    // create the payload
    // @see https://developer.github.com/v3/markdown/
    $postdata = json_encode(
        array(
            'text' => $text,
            'mode' => ($repositoryContext != null ? 'gfm' : 'markdown'),
            'context' => $repositoryContext
        )
    );

    // prepare the HTTP 1.1 POST Request
    $opts = array('http' =>
        array(
            'method'  => 'POST',
            'protocol_version' => '1.1',
            'user_agent' => $repositoryContext,
            'header'  => array(
                'Content-type: application/x-www-form-urlencoded;charset=UTF-8',
                'Connection: close',
                'Accept: application/vnd.github.v3+json'
            ),
            'content' => $postdata
        )
    );

    // send request
    return file_get_contents('https://api.github.com/markdown', false, stream_context_create($opts));
}

Usage#

The optional $repositoryContext argument allows your to define the context which should be used for rendering to e.g. enable issue linking

// fetch the document (example)
$document = file_get_contents('https://raw.githubusercontent.com/AndiDittrich/WordPress.Enlighter/master/CHANGES.md');

// render html using the GitHub GFM API
$html = renderGFM($document, 'AndiDittrich/WordPress.Enlighter');

// show it!
echo $html;

 

 

You may have noticed, that normal users (especially Author’s and Contributor’s) are not allowed to use all kind of HTML Tags and related Attributes.

Those elements got removed by the WordPress buil-in KSES Filter – and it’s a very useful feature in matter of security to prevent html-code-injection.

But sometimes it is required to enable some additional html tags and/or attributes. You can modify the list of allowed html tags and attributes by appling a custom filter:

The Filter#

Example how to allow EnlighterJS related attributes for pre and code tags

function ksesAllowHtmlCodeAttributes($data, $context){
    // only apply filter on post-context
    if ($context === 'post'){

        // list of all available enlighterjs attributes
        $allowedAttributes = array(
            'data-enlighter-language' => true,
            'data-enlighter-theme' => true,
            'data-enlighter-group' => true,
            'data-enlighter-title' => true,
            'data-enlighter-linenumbers' => true,
            'data-enlighter-highlight' => true,
            'data-enlighter-lineoffset' => true
        );

        // apply to pre and code tags
        $data['pre'] = array_merge($data['pre'], $allowedAttributes);
        $data['code'] = array_merge($data['code'], $allowedAttributes);
    }

    return $data;
}

// add the filter function (2 arguments and priority 100)
add_filter('wp_kses_allowed_html', 'ksesAllowHtmlCodeAttributes', 100, 2);

 

 

 

Sometimes it can be very useful to have magical constants like __FILENAME__ or __LINE__ available within your sourcecode – especially for debugging or in merged files. Unfortunately, such feature is missing in javascript but it is possible to implement it by yourself using a file-postprocessing filter in your gulp build script. Thanks to gulp-concat-util, it’s […]

Howto: (re-)Enable SCP/SSH Login on Synology DSM 6.0 for non admin users [UPDATE]

a update which may break your backup tasks! change the user shell permanently

When updating to the latest DSM 6.0 final, you may have noticed that your scp backup accounts won’t work anymore (this also affects ssh the login). It is caused by a reset of the login shell settings in /etc/passwd ! It is happened in part of a “security enhancement” – normal users, which does not […]

Prevent Errors from breaking Gulp watch

gulp-plumber, custom error handler, gulp-prettyerror

As an intermediate javascript developer, you may using gulp these days – a great and straightforward streaming build system with a lot of advantages compared to grunt. For example, i’ve switched from a bunch of custom, ANT based scripts to gulp for the next EnlighterJS major version and it saves a lot of time! Especially […]

Tweaking Minidlna Media Server on AsusWRT Merlin

usb storage, disable album arts, performance

You’re running AsusWRT Merlin and have some trouble with minidlna, e.g. bad media indexing performance or broken media databases ?

This can be caused by using an USB Stick as media database storage! Internally, minidlna is using an SQLite database to store the media file index – and sometime this database may broke (slow, unsynced file operations, user terminated processes).

As a workaround, it’s possible to move the media database to the temporary filesystem (ramdisk). As a disadvantage, on every system shutdown (reboot/power cycle) the database will be destroyed. But it only takes a view minutes to recreate it, because the ramdisk storage is a lot faster than the attached USB drive!

Just create an additional user config file in your JFFS /jffs/configs/minidlna.conf.add (will be automatically appended to the system generated minidlna.conf file!)

# Move the database to the tmp directory (ramdisk, will be recreated on reboot !!)
db_dir=/tmp/.minidlna

# create a custom minidlna logfile
log_dir=/var/log

# disable album art indexing
album_art_names=NO_ALBUM_ARTS.x

 

Ubuntu 15.10 with Dell Wireless 5570 HSPA+ (42Mbps) Mobile Broadband Card

mbmi to qmi modeswitch, magical ffc-auth sequence

A several days ago, i’ve replaced the Gobi 2000 WWAN Card with a newer version, a Dell 5570 Module. It’s a branded Sierra Wireless card, so i hoped it will work out of the box on Ubuntu 15.10 – but nothing. After some investigations if figured out, that the card is locked in “low-power” / […]

Ubuntu 15.10 – Disable Wake on LAN (WOL) permanently

ubuntu, systemd, Wily Werewolf, notebook, battery power drain

Preface# In some cases, Wake on LAN is enabled by default and you cannot disable it in your BIOS/UEFI because the setting is not available. On notebooks/ultrabooks, WOL can drain/discharge your battery even your device is powered-off! There are a several guides out there, which didn’t even work. The general mistake is, that the WOL […]

Single File ReCaptcha 2 PHP Client

leading captcha system, curl, php, json-response

Today, a web-form without a proven captcha system generates a lot of spam entries and data-trash in your database. One of the best is ReCaptcha (even the latest v2).

Google provides an easy to use ReCaptcha PHP Client – but it’s a bit over engineered! You need a bunch of PHP files and a composer based environment to use it out of the box. This can cause some trouble in highly customized/optimized projects.

Therefore, here is a “one-file” solution which works without any configuration overhead:

Usage#

require('ReCaptcha.php');

// register your secret
ReCaptcha::setSecret('<your-secret>');

// some code ...

// check user form
if (ReCaptcha::isValid()){ ...

One-File Solution#

// Developer Guide: https://developers.google.com/recaptcha/docs/verify
class ReCaptcha{

    // ReCaptcha API Endpoint
    const SITE_VERIFY_URL = 'https://www.google.com/recaptcha/api/siteverify';

    // the last result
    private static $_result = null;

    // client secret
    private static $_secret = null;

    // validate
    public static function isValid(){
        // token available ?
        if (!isset($_POST['g-recaptcha-response'])){
            return false;
        }

        // extract token
        $token = trim($_POST['g-recaptcha-response']);

        // generate url
        $params = http_build_query(array(
            'secret' => self::$_secret,
            'response' => $token,
            'remoteIp' => $_SERVER['REMOTE_ADDR']
        ), '', '&');

        // create curl based post request
        $handle = curl_init(self::SITE_VERIFY_URL);
        $options = array(
            CURLOPT_POST => true,
            CURLOPT_POSTFIELDS => $params,
            CURLOPT_HTTPHEADER => array(
                'Content-Type: application/x-www-form-urlencoded'
            ),
            CURLINFO_HEADER_OUT => false,
            CURLOPT_HEADER => false,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_SSL_VERIFYPEER => true
        );
        curl_setopt_array($handle, $options);
        $response = curl_exec($handle);
        curl_close($handle);

        // decode response
        self::$_result = json_decode($response, true);

        // check
        return (self::$_result['success'] === true);
    }

    // error occurred ?
    public static function isError(){
        return (self::$_result['success'] === false);
    }

    // get error message from last request
    public static function getErrorMessages(){
        return self::$_result['error-codes'];
    }

    // set client secret
    public static function setSecret($s){
        self::$_secret = $s;
    }
}

 

Node.js Simple Command Line Confirm Messages

user confirmation, terminal actions, yes, no

Sometime, special terminal commands can be dangerous for your users. To ensure that they are really want to run the command the proven “best practise” is to wait for an explicit user confirmation by typing yes/no into the terminal.

Install “prompt” using NPM#

First of all, you have to install prompt – a powerfull package for command line prompts & user interactions. The “–save” option will add this package to your package.json file.

npm install prompt --save

Confirm Dialog#

After installing the prompt package you can use the following code to show a confirm dialog to your users.

var _prompt = require('prompt');

// user confirmation required!
_prompt.start();

// disable prefix message & colors
_prompt.message = '';
_prompt.delimiter = '';
_prompt.colors = false;

// wait for user confirmation
_prompt.get({
    properties: {
        
        // setup the dialog
        confirm: {
            // allow yes, no, y, n, YES, NO, Y, N as answer
            pattern: /^(yes|no|y|n)$/gi,
            description: 'Do you really want to format the filesystem and delete all file ?',
            message: 'Type yes/no',
            required: true,
            default: 'no'
        }
    }
}, function (err, result){
    // transform to lower case
    var c = result.confirm.toLowerCase();

    // yes or y typed ? otherwise abort
    if (c!='y' && c!='yes'){
        console.log('ABORT');
        return;
    }
    
    // your code
    console.log('Action confirmed');
    
});