Changeset 42770 for trunk/src/wp-includes/formatting.php

Timestamp:

03/02/2018 02:41:04 PM (7 years ago)

Author:

azaozz

Message:

Add pre-save content filter to make target=_blank always secure.

Props notnownikki, iseulde, azaozz
Fixes #43187

File:

• trunk/src/wp-includes/formatting.php (modified) (1 diff)

trunk/src/wp-includes/formatting.php

@@ -3025 +3025 @@
 
 /**
+ * Adds rel noreferrer and noopener to all HTML A elements that have a target.
+ *
+ * @param string $text Content that may contain HTML A elements.
+ * @return string Converted content.
+ */
+function wp_targeted_link_rel( $text ) {
+    // Don't run (more expensive) regex if no links with targets.
+    if ( stripos( $text, 'target' ) !== false && stripos( $text, '<a ' ) !== false ) {
+        $text = preg_replace_callback( '|<a\s([^>]*target\s*=[^>]*)>|i', 'wp_targeted_link_rel_callback', $text );
+    }
+
+    return $text;
+}
+
+/**
+ * Callback to add rel="noreferrer noopener" string to HTML A element.
+ *
+ * Will not duplicate existing noreferrer and noopener values
+ * to prevent from invalidating the HTML.
+ *
+ * @param array $matches Single Match
+ * @return string HTML A Element with rel noreferrer noopener in addition to any existing values
+ */
+function wp_targeted_link_rel_callback( $matches ) {
+    $link_html = $matches[1];
+    $rel_match = array();
+
+    /**
+     * Filters the rel values that are added to links with `target` attribute.
+     *
+     * @since 5.0.0
+     *
+     * @param string The rel values.
+     * @param string $link_html The matched content of the link tag including all HTML attributes.
+     */
+    $rel = apply_filters( 'wp_targeted_link_rel', 'noopener noreferrer', $link_html );
+
+    // Value with delimiters, spaces around are optional.
+    $attr_regex = '|rel\s*=\s*?(\\\\{0,1}["\'])(.*?)\\1|i';
+    preg_match( $attr_regex, $link_html, $rel_match );
+
+    if ( empty( $rel_match[0] ) ) {
+        // No delimiters, try with a single value and spaces, because `rel =  va"lue` is totally fine...
+        $attr_regex = '|rel\s*=(\s*)([^\s]*)|i';
+        preg_match( $attr_regex, $link_html, $rel_match );
+    }
+
+    if ( ! empty( $rel_match[0] ) ) {
+        $parts = preg_split( '|\s+|', strtolower( $rel_match[2] ) );
+        $parts = array_map( 'esc_attr', $parts );
+        $needed = explode( ' ', $rel );
+        $parts = array_unique( array_merge( $parts, $needed ) );
+        $delimiter = trim( $rel_match[1] ) ? $rel_match[1] : '"';
+        $rel = 'rel=' . $delimiter . trim( implode( ' ', $parts ) ) . $delimiter;
+        $link_html = str_replace( $rel_match[0], $rel, $link_html );
+    } else {
+        $link_html .= " rel=\"$rel\"";
+    }
+
+    return "<a $link_html>";
+}
+
+/**
  * Convert one smiley code to the icon graphic file equivalent.
  *