Pings/Trackbacks: Output pingback link from core

src/wp-content/themes/twentyeleven/header.php

@@ -44,7 +44,6 @@
 	</title>
 <link rel="profile" href="https://gmpg.org/xfn/11" />
 <link rel="stylesheet" media="all" href="<?php echo esc_url( get_stylesheet_uri() ); ?>?ver=20260520" />
-<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 <?php
 	/*
 	 * We add some JavaScript to pages with the comment form

src/wp-content/themes/twentyfifteen/header.php

@@ -14,7 +14,6 @@
 	<meta charset="<?php bloginfo( 'charset' ); ?>">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<link rel="profile" href="https://gmpg.org/xfn/11">
-	<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 	<?php wp_head(); ?>
 </head>
 

src/wp-content/themes/twentyfourteen/header.php

@@ -15,7 +15,6 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<title><?php wp_title( '|', true, 'right' ); ?></title>
 	<link rel="profile" href="https://gmpg.org/xfn/11">
-	<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 	<?php wp_head(); ?>
 </head>
 

src/wp-content/themes/twentynineteen/inc/template-functions.php

@@ -49,11 +49,8 @@ function twentynineteen_post_classes( $classes ) {
  * Adds a pingback url auto-discovery header for single posts, pages, or attachments.
  */
 function twentynineteen_pingback_header() {
-	if ( is_singular() && pings_open() ) {
-		echo '<link rel="pingback" href="', esc_url( get_bloginfo( 'pingback_url' ) ), '">';
-	}
+	wp_pingback_link();
 }
-add_action( 'wp_head', 'twentynineteen_pingback_header' );
 
 /**
  * Changes comment form default fields.

src/wp-content/themes/twentyseventeen/functions.php

@@ -427,11 +427,8 @@ function twentyseventeen_javascript_detection() {
  * Adds a pingback url auto-discovery header for singularly identifiable articles.
  */
 function twentyseventeen_pingback_header() {
-	if ( is_singular() && pings_open() ) {
-		printf( '<link rel="pingback" href="%s">' . "\n", esc_url( get_bloginfo( 'pingback_url' ) ) );
-	}
+	wp_pingback_link();
 }
-add_action( 'wp_head', 'twentyseventeen_pingback_header' );
 
 /**
  * Displays custom color CSS.

src/wp-content/themes/twentysixteen/header.php

@@ -15,9 +15,6 @@
 	<meta charset="<?php bloginfo( 'charset' ); ?>">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<link rel="profile" href="https://gmpg.org/xfn/11">
-	<?php if ( is_singular() && pings_open( get_queried_object() ) ) : ?>
-	<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
-	<?php endif; ?>
 	<?php wp_head(); ?>
 </head>
 

src/wp-content/themes/twentyten/header.php

@@ -43,7 +43,6 @@
 	</title>
 <link rel="profile" href="https://gmpg.org/xfn/11" />
 <link rel="stylesheet" media="all" href="<?php echo esc_url( get_stylesheet_uri() ); ?>?ver=20260520" />
-<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 <?php
 	/*
 	 * We add some JavaScript to pages with the comment form

src/wp-content/themes/twentythirteen/header.php

@@ -15,7 +15,6 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<title><?php wp_title( '|', true, 'right' ); ?></title>
 	<link rel="profile" href="https://gmpg.org/xfn/11">
-	<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 	<?php wp_head(); ?>
 </head>
 

src/wp-content/themes/twentytwelve/header.php

@@ -15,7 +15,6 @@
 <meta name="viewport" content="width=device-width, initial-scale=1.0" />
 <title><?php wp_title( '|', true, 'right' ); ?></title>
 <link rel="profile" href="https://gmpg.org/xfn/11" />
-<link rel="pingback" href="<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>">
 <?php wp_head(); ?>
 </head>
 

src/wp-content/themes/twentytwentyone/inc/template-functions.php

@@ -60,11 +60,8 @@ function twenty_twenty_one_post_classes( $classes ) {
  * @return void
  */
 function twenty_twenty_one_pingback_header() {
-	if ( is_singular() && pings_open() ) {
-		echo '<link rel="pingback" href="', esc_url( get_bloginfo( 'pingback_url' ) ), '">';
-	}
+	wp_pingback_link();
 }
-add_action( 'wp_head', 'twenty_twenty_one_pingback_header' );
 
 /**
  * Removes the `no-js` class from body if JS is supported.

src/wp-includes/default-filters.php

@@ -359,6 +359,7 @@
 add_action( 'wp_head', 'feed_links', 2 );
 add_action( 'wp_head', 'feed_links_extra', 3 );
 add_action( 'wp_head', 'rsd_link' );
+add_action( 'wp_head', 'wp_pingback_link' );
 add_action( 'wp_head', 'locale_stylesheet' );
 add_action( 'publish_future_post', 'check_and_publish_future_post', 10, 1 );
 add_action( 'wp_head', 'wp_robots', 1 );

src/wp-includes/general-template.php

@@ -3561,6 +3561,24 @@ function rsd_link() {
 	);
 }
 
+/**
+ * Displays the link to the pingback XML-RPC endpoint.
+ *
+ * @since 7.1.0
+ *
+ * @return void
+ */
+function wp_pingback_link() {
+	if ( ! is_singular() || ! pings_open( get_queried_object() ) ) {
+		return;
+	}
+
+	printf(
+		'<link rel="pingback" href="%s" />' . "\n",
+		esc_url( get_bloginfo( 'pingback_url', 'display' ) )
+	);
+}
+
 /**
  * Displays a referrer `strict-origin-when-cross-origin` meta tag.
  *

src/wp-includes/theme-compat/header.php

@@ -24,7 +24,6 @@
 <title><?php echo wp_get_document_title(); ?></title>
 
 <link rel="stylesheet" href="<?php bloginfo( 'stylesheet_url' ); ?>" media="screen" />
-<link rel="pingback" href="<?php bloginfo( 'pingback_url' ); ?>" />
 
 <?php if ( file_exists( get_stylesheet_directory() . '/images/kubrickbgwide.jpg' ) ) { ?>
 <style media="screen">

tests/phpunit/tests/general/wpPingbackLink.php

@@ -0,0 +1,94 @@
+<?php
+/**
+ * Test wp_pingback_link().
+ *
+ * @group general
+ * @group template
+ *
+ * @covers ::wp_pingback_link
+ */
+class Tests_General_WpPingbackLink extends WP_UnitTestCase {
+	/**
+	 * @ticket 43791
+	 */
+	public function test_wp_pingback_link_is_hooked_to_wp_head() {
+		$this->assertSame( 10, has_action( 'wp_head', 'wp_pingback_link' ) );
+	}
+
+	/**
+	 * @ticket 43791
+	 */
+	public function test_wp_pingback_link_outputs_link_on_singular_when_pings_are_open() {
+		$post_id = self::factory()->post->create(
+			array(
+				'ping_status' => 'open',
+			)
+		);
+
+		$this->go_to( get_permalink( $post_id ) );
+
+		$expected = sprintf(
+			'<link rel="pingback" href="%s" />' . "\n",
+			esc_url( get_bloginfo( 'pingback_url', 'display' ) )
+		);
+
+		$this->assertSame( $expected, get_echo( 'wp_pingback_link' ) );
+	}
+
+	/**
+	 * @ticket 43791
+	 */
+	public function test_wp_pingback_link_respects_filtered_pingback_url() {
+		$post_id = self::factory()->post->create(
+			array(
+				'ping_status' => 'open',
+			)
+		);
+		$filter  = static function ( $output, $show ) {
+			if ( 'pingback_url' === $show ) {
+				return 'https://example.com/pingback';
+			}
+
+			return $output;
+		};
+
+		add_filter( 'bloginfo_url', $filter, 10, 2 );
+		$this->go_to( get_permalink( $post_id ) );
+
+		$this->assertSame(
+			'<link rel="pingback" href="https://example.com/pingback" />' . "\n",
+			get_echo( 'wp_pingback_link' )
+		);
+		remove_filter( 'bloginfo_url', $filter, 10 );
+	}
+
+	/**
+	 * @ticket 43791
+	 */
+	public function test_wp_pingback_link_outputs_nothing_when_pings_are_closed() {
+		$post_id = self::factory()->post->create(
+			array(
+				'ping_status' => 'closed',
+			)
+		);
+
+		$this->go_to( get_permalink( $post_id ) );
+
+		$this->assertEmpty( get_echo( 'wp_pingback_link' ) );
+	}
+
+	/**
+	 * @ticket 43791
+	 */
+	public function test_wp_pingback_link_outputs_nothing_when_not_singular() {
+		self::factory()->post->create(
+			array(
+				'ping_status' => 'open',
+			)
+		);
+
+		$this->go_to( home_url( '/' ) );
+
+		$this->assertEmpty( get_echo( 'wp_pingback_link' ) );
+	}
+}