Ticket #48022: 48022.1.diff

src/wp-includes/formatting.php

@@ -3075 +3075 @@
         return "<a $text rel=\"" . esc_attr( $rel ) . '">';
 }
 
+/**
+ * Adds rel ugc string to all HTML A elements in content.
+ *
+ * @since 5.3.0
+ *
+ * @param string $text Content that may contain HTML A elements.
+ * @return string Converted content.
+ */
+function wp_rel_ugc( $text ) {
+        // This is a pre save filter, so text is already escaped.
+        $text = stripslashes( $text );
+        $text = preg_replace_callback( '|<a (.+?)>|i', 'wp_rel_ugc_callback', $text );
+        return wp_slash( $text );
+}
+
+/**
+ * Callback to add rel=ugc string to HTML A element.
+ *
+ * Will remove already existing rel="ugc" and rel='ugc' from the
+ * string to prevent from invalidating (X)HTML.
+ *
+ * @since 5.3.0
+ *
+ * @param array $matches Single Match
+ * @return string HTML A Element with rel ugc.
+ */
+function wp_rel_ugc_callback( $matches ) {
+        $text = $matches[1];
+        $atts = wp_kses_hair( $matches[1], wp_allowed_protocols() );
+        $rel  = 'ugc';
+
+        if ( ! empty( $atts['href'] ) ) {
+                if ( in_array( strtolower( wp_parse_url( $atts['href']['value'], PHP_URL_SCHEME ) ), array( 'http', 'https' ), true ) ) {
+                        if ( strtolower( wp_parse_url( $atts['href']['value'], PHP_URL_HOST ) ) === strtolower( wp_parse_url( home_url(), PHP_URL_HOST ) ) ) {
+                                return "<a $text>";
+                        }
+                }
+        }
+
+        if ( ! empty( $atts['rel'] ) ) {
+                $parts = array_map( 'trim', explode( ' ', $atts['rel']['value'] ) );
+                if ( false === array_search( 'ugc', $parts ) ) {
+                        $parts[] = 'ugc';
+                }
+                $rel = implode( ' ', $parts );
+                unset( $atts['rel'] );
+
+                $html = '';
+                foreach ( $atts as $name => $value ) {
+                        if ( isset( $value['vless'] ) && 'y' === $value['vless'] ) {
+                                $html .= $name . ' ';
+                        } else {
+                                $html .= "{$name}=\"" . esc_attr( $value['value'] ) . '" ';
+                        }
+                }
+                $text = trim( $html );
+        }
+        return "<a $text rel=\"" . esc_attr( $rel ) . '">';
+}
+
 /**
  * Adds rel noreferrer and noopener to all HTML A elements that have a target.
  *