class-jetpack-podcast-feed-locator.php — Jetpack – WP Security, Backup, Speed, & Growth 12.8.3

jetpack / _inc / lib / class-jetpack-podcast-feed-locator.php

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class-jetpack-podcast-feed-locator.php

112 lines

1	<?php
2	/**
3	* Extension of the SimplePie_Locator class, to detect podcast feeds
4	*
5	* @package automattic/jetpack
6	*/
7
8	/**
9	* Class Jetpack_Podcast_Feed_Locator
10	*/
11	class Jetpack_Podcast_Feed_Locator extends SimplePie_Locator {
12	/**
13	* Overrides the locator is_feed function to check for
14	* appropriate podcast elements.
15	*
16	* @param SimplePie_File $file The file being checked.
17	* @param boolean $check_html Adds text/html to the mimetypes checked.
18	*/
19	public function is_feed( $file, $check_html = false ) {
20	return parent::is_feed( $file, $check_html ) && $this->is_podcast_feed( $file );
21	}
22
23	/**
24	* Checks the contents of the file for elements that make
25	* it a podcast feed.
26	*
27	* @param SimplePie_File $file The file being checked.
28	*/
29	private function is_podcast_feed( $file ) {
30	// If we can't read the DOM assume it's a podcast feed, we'll work
31	// it out later.
32	if ( ! class_exists( 'DOMDocument' ) ) {
33	return true;
34	}
35
36	$feed_dom = $this->safely_load_xml( $file->body );
37
38	// Do this as either/or but prioritise the itunes namespace. It's pretty likely
39	// that it's a podcast feed we've found if that namespace is present.
40	return $feed_dom && $this->has_itunes_ns( $feed_dom ) && $this->has_audio_enclosures( $feed_dom );
41	}
42
43	/**
44	* Safely loads an XML file
45	*
46	* @param string $xml A string of XML to load.
47	* @return DOMDocument\|false A restulting DOM document or `false` if there is an error.
48	*/
49	private function safely_load_xml( $xml ) {
50	$disable_entity_loader = PHP_VERSION_ID < 80000;
51
52	if ( $disable_entity_loader && ! function_exists( 'libxml_disable_entity_loader' ) ) {
53	return false;
54	}
55
56	if ( $disable_entity_loader ) {
57	// This function has been deprecated in PHP 8.0 because in libxml 2.9.0, external entity loading
58	// is disabled by default, so this function is no longer needed to protect against XXE attacks.
59	// phpcs:ignore Generic.PHP.DeprecatedFunctions.Deprecated, PHPCompatibility.FunctionUse.RemovedFunctions.libxml_disable_entity_loaderDeprecated
60	$loader = libxml_disable_entity_loader( true );
61	}
62
63	$errors = libxml_use_internal_errors( true );
64
65	$return = new DOMDocument();
66	if ( ! $return->loadXML( $xml ) ) {
67	return false;
68	}
69
70	libxml_use_internal_errors( $errors );
71
72	if ( $disable_entity_loader && isset( $loader ) ) {
73	// phpcs:ignore Generic.PHP.DeprecatedFunctions.Deprecated, PHPCompatibility.FunctionUse.RemovedFunctions.libxml_disable_entity_loaderDeprecated
74	libxml_disable_entity_loader( $loader );
75	}
76
77	return $return;
78	}
79
80	/**
81	* Checks the RSS feed for the presence of the itunes podcast namespace.
82	* It's pretty loose and just checks the URI for itunes.com
83	*
84	* @param DOMDocument $dom The XML document to check.
85	* @return boolean Whether the itunes namespace is defined.
86	*/
87	private function has_itunes_ns( $dom ) {
88	$xpath = new DOMXPath( $dom );
89	foreach ( $xpath->query( 'namespace::*' ) as $node ) {
90	// phpcs:disable WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
91	// nodeValue is not valid, but it's part of the DOM API that we don't control.
92	if ( strstr( $node->nodeValue, 'itunes.com' ) ) {
93	return true;
94	}
95	// phpcs:enable
96	}
97	return false;
98	}
99
100	/**
101	* Checks the RSS feed for the presence of enclosures with an audio mimetype.
102	*
103	* @param DOMDocument $dom The XML document to check.
104	* @return boolean Whether enclosures were found.
105	*/
106	private function has_audio_enclosures( $dom ) {
107	$xpath = new DOMXPath( $dom );
108	$enclosures = $xpath->query( "//enclosure[starts-with(@type,'audio/')]" );
109	return ! $enclosures ? false : $enclosures->length > 0;
110	}
111	}
112