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|
<?php
namespace PicoFeed\Filter;
use DOMXpath;
use PicoFeed\Parser\XmlParser;
/**
* Tag Filter class
*
* @author Frederic Guillot
* @package Filter
*/
class Tag
{
/**
* Tags blacklist (Xpath expressions)
*
* @access private
* @var array
*/
private $tag_blacklist = array(
'//script',
'//style',
);
/**
* Tags whitelist
*
* @access private
* @var array
*/
private $tag_whitelist = array(
'audio',
'video',
'source',
'dt',
'dd',
'dl',
'table',
'caption',
'tr',
'th',
'td',
'tbody',
'thead',
'h2',
'h3',
'h4',
'h5',
'h6',
'strong',
'em',
'code',
'pre',
'blockquote',
'p',
'ul',
'li',
'ol',
'br',
'del',
'a',
'img',
'figure',
'figcaption',
'cite',
'time',
'abbr',
'iframe',
'q',
);
/**
* Check if the tag is allowed and is not a pixel tracker
*
* @access public
* @param string $tag Tag name
* @param array $attributes Attributes dictionary
* @return boolean
*/
public function isAllowed($tag, array $attributes)
{
return $this->isAllowedTag($tag) && ! $this->isPixelTracker($tag, $attributes);
}
/**
* Return the HTML opening tag
*
* @access public
* @param string $tag Tag name
* @param string $attributes Attributes converted in html
* @return string
*/
public function openHtmlTag($tag, $attributes = '')
{
return '<'.$tag.(empty($attributes) ? '' : ' '.$attributes).($this->isSelfClosingTag($tag) ? '/>' : '>');
}
/**
* Return the HTML closing tag
*
* @access public
* @param string $tag Tag name
* @return string
*/
public function closeHtmlTag($tag)
{
return $this->isSelfClosingTag($tag) ? '' : '</'.$tag.'>';
}
/**
* Return true is the tag is self-closing
*
* @access public
* @param string $tag Tag name
* @return boolean
*/
public function isSelfClosingTag($tag)
{
return $tag === 'br' || $tag === 'img';
}
/**
* Check if a tag is on the whitelist
*
* @access public
* @param string $tag Tag name
* @return boolean
*/
public function isAllowedTag($tag)
{
return in_array($tag, $this->tag_whitelist);
}
/**
* Detect if an image tag is a pixel tracker
*
* @access public
* @param string $tag Tag name
* @param array $attributes Tag attributes
* @return boolean
*/
public function isPixelTracker($tag, array $attributes)
{
return $tag === 'img' &&
isset($attributes['height']) && isset($attributes['width']) &&
$attributes['height'] == 1 && $attributes['width'] == 1;
}
/**
* Remove script tags
*
* @access public
* @param string $data Input data
* @return string
*/
public function removeBlacklistedTags($data)
{
$dom = XmlParser::getDomDocument($data);
if ($dom === false) {
return '';
}
$xpath = new DOMXpath($dom);
$nodes = $xpath->query(implode(' | ', $this->tag_blacklist));
foreach ($nodes as $node) {
$node->parentNode->removeChild($node);
}
return $dom->saveXML();
}
/**
* Remove empty tags
*
* @access public
* @param string $data Input data
* @return string
*/
public function removeEmptyTags($data)
{
return preg_replace('/<([^<\/>]*)>([\s]*?|(?R))<\/\1>/imsU', '', $data);
}
/**
* Replace <br/><br/> by only one
*
* @access public
* @param string $data Input data
* @return string
*/
public function removeMultipleBreakTags($data)
{
return preg_replace("/(<br\s*\/?>\s*)+/", "<br/>", $data);
}
/**
* Set whitelisted tags adn attributes for each tag
*
* @access public
* @param array $values List of tags: ['video' => ['src', 'cover'], 'img' => ['src']]
* @return Tag
*/
public function setWhitelistedTags(array $values)
{
$this->tag_whitelist = $values ?: $this->tag_whitelist;
return $this;
}
}
|
