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<?php
namespace Shaarli\Formatter;
use Shaarli\Config\ConfigManager;
/**
* Class BookmarkMarkdownFormatter
*
* Format bookmark description into Markdown format.
*
* @package Shaarli\Formatter
*/
class BookmarkMarkdownFormatter extends BookmarkDefaultFormatter
{
/**
* When this tag is present in a bookmark, its description should not be processed with Markdown
*/
const NO_MD_TAG = 'nomarkdown';
/** @var \Parsedown instance */
protected $parsedown;
/** @var bool used to escape HTML in Markdown or not.
* It MUST be set to true for shared instance as HTML content can
* introduce XSS vulnerabilities.
*/
protected $escape;
/**
* @var array List of allowed protocols for links inside bookmark's description.
*/
protected $allowedProtocols;
/**
* LinkMarkdownFormatter constructor.
*
* @param ConfigManager $conf instance
*/
public function __construct(ConfigManager $conf)
{
parent::__construct($conf);
$this->parsedown = new \Parsedown();
$this->escape = $conf->get('security.markdown_escape', true);
$this->allowedProtocols = $conf->get('security.allowed_protocols', []);
}
/**
* @inheritdoc
*/
public function formatDescription($bookmark)
{
if (in_array(self::NO_MD_TAG, $bookmark->getTags())) {
return parent::formatDescription($bookmark);
}
$processedDescription = $bookmark->getDescription();
$processedDescription = $this->filterProtocols($processedDescription);
$processedDescription = $this->formatHashTags($processedDescription);
$processedDescription = $this->reverseEscapedHtml($processedDescription);
$processedDescription = $this->parsedown
->setMarkupEscaped($this->escape)
->setBreaksEnabled(true)
->text($processedDescription);
$processedDescription = $this->sanitizeHtml($processedDescription);
if (!empty($processedDescription)) {
$processedDescription = '<div class="markdown">'. $processedDescription . '</div>';
}
return $processedDescription;
}
/**
* Remove the NO markdown tag if it is present
*
* @inheritdoc
*/
protected function formatTagList($bookmark)
{
$out = parent::formatTagList($bookmark);
if (($pos = array_search(self::NO_MD_TAG, $out)) !== false) {
unset($out[$pos]);
return array_values($out);
}
return $out;
}
/**
* Replace not whitelisted protocols with http:// in given description.
* Also adds `index_url` to relative links if it's specified
*
* @param string $description input description text.
*
* @return string $description without malicious link.
*/
protected function filterProtocols($description)
{
$allowedProtocols = $this->allowedProtocols;
$indexUrl = ! empty($this->contextData['index_url']) ? $this->contextData['index_url'] : '';
return preg_replace_callback(
'#]\((.*?)\)#is',
function ($match) use ($allowedProtocols, $indexUrl) {
$link = startsWith($match[1], '?') || startsWith($match[1], '/') ? $indexUrl : '';
$link .= whitelist_protocols($match[1], $allowedProtocols);
return ']('. $link.')';
},
$description
);
}
/**
* Replace hashtag in Markdown links format
* E.g. `#hashtag` becomes `[#hashtag](?addtag=hashtag)`
* It includes the index URL if specified.
*
* @param string $description
*
* @return string
*/
protected function formatHashTags($description)
{
$indexUrl = ! empty($this->contextData['index_url']) ? $this->contextData['index_url'] : '';
/*
* To support unicode: http://stackoverflow.com/a/35498078/1484919
* \p{Pc} - to match underscore
* \p{N} - numeric character in any script
* \p{L} - letter from any language
* \p{Mn} - any non marking space (accents, umlauts, etc)
*/
$regex = '/(^|\s)#([\p{Pc}\p{N}\p{L}\p{Mn}]+)/mui';
$replacement = '$1[#$2]('. $indexUrl .'?addtag=$2)';
$descriptionLines = explode(PHP_EOL, $description);
$descriptionOut = '';
$codeBlockOn = false;
$lineCount = 0;
foreach ($descriptionLines as $descriptionLine) {
// Detect line of code: starting with 4 spaces,
// except lists which can start with +/*/- or `2.` after spaces.
$codeLineOn = preg_match('/^ +(?=[^\+\*\-])(?=(?!\d\.).)/', $descriptionLine) > 0;
// Detect and toggle block of code
if (!$codeBlockOn) {
$codeBlockOn = preg_match('/^```/', $descriptionLine) > 0;
} elseif (preg_match('/^```/', $descriptionLine) > 0) {
$codeBlockOn = false;
}
if (!$codeBlockOn && !$codeLineOn) {
$descriptionLine = preg_replace($regex, $replacement, $descriptionLine);
}
$descriptionOut .= $descriptionLine;
if ($lineCount++ < count($descriptionLines) - 1) {
$descriptionOut .= PHP_EOL;
}
}
return $descriptionOut;
}
/**
* Remove dangerous HTML tags (tags, iframe, etc.).
* Doesn't affect <code> content (already escaped by Parsedown).
*
* @param string $description input description text.
*
* @return string given string escaped.
*/
protected function sanitizeHtml($description)
{
$escapeTags = array(
'script',
'style',
'link',
'iframe',
'frameset',
'frame',
);
foreach ($escapeTags as $tag) {
$description = preg_replace_callback(
'#<\s*'. $tag .'[^>]*>(.*</\s*'. $tag .'[^>]*>)?#is',
function ($match) {
return escape($match[0]);
},
$description
);
}
$description = preg_replace(
'#(<[^>]+\s)on[a-z]*="?[^ "]*"?#is',
'$1',
$description
);
return $description;
}
protected function reverseEscapedHtml($description)
{
return unescape($description);
}
}
|
