From f2daa0b4e6fe871ad905f5a2fb3adc78d0825148 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Tue, 12 Mar 2019 22:23:22 +0000
Subject: [PATCH] Formatting: Improve `rel="nofollow"` handling in comments.

Merges [44833] to the 4.6 branch.
Built from https://develop.svn.wordpress.org/branches/4.6@44839


git-svn-id: http://core.svn.wordpress.org/branches/4.6@44671 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/formatting.php | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 2701c1a1a9..22d3d6ef8c 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -2716,10 +2716,12 @@ function wp_rel_nofollow_callback( $matches ) {
 	$atts = shortcode_parse_atts( $matches[1] );
 	$rel  = 'nofollow';
 
-	if ( preg_match( '%href=["\'](' . preg_quote( set_url_scheme( home_url(), 'http' ) ) . ')%i', $text ) ||
-	     preg_match( '%href=["\'](' . preg_quote( set_url_scheme( home_url(), 'https' ) ) . ')%i', $text )
-	) {
-		return "<a $text>";
+	if ( ! empty( $atts['href'] ) ) {
+		if ( in_array( strtolower( wp_parse_url( $atts['href'], PHP_URL_SCHEME ) ), array( 'http', 'https' ), true ) ) {
+			if ( strtolower( wp_parse_url( $atts['href'], PHP_URL_HOST ) ) === strtolower( wp_parse_url( home_url(), PHP_URL_HOST ) ) ) {
+				return "<a $text>";
+			}
+		}
 	}
 
 	if ( ! empty( $atts['rel'] ) ) {
@@ -2732,11 +2734,11 @@ function wp_rel_nofollow_callback( $matches ) {
 
 		$html = '';
 		foreach ( $atts as $name => $value ) {
-			$html .= "{$name}=\"$value\" ";
+			$html .= "{$name}=\"" . esc_attr( $value ) . "\" ";
 		}
 		$text = trim( $html );
 	}
-	return "<a $text rel=\"$rel\">";
+	return "<a $text rel=\"" . esc_attr( $rel ) . "\">";
 }
 
 /**