Ticket #23021: 23021.6.refreshed.diff

wp-includes/functions.php

@@ -902 +902 @@
 function wp_get_nocache_headers() {
         $headers = array(
                 'Expires' => 'Wed, 11 Jan 1984 05:00:00 GMT',
-                'Last-Modified' => '',
                 'Cache-Control' => 'no-cache, must-revalidate, max-age=0',
                 'Pragma' => 'no-cache',
         );
@@ -910 +909 @@
         if ( function_exists('apply_filters') ) {
                 $headers = (array) apply_filters('nocache_headers', $headers);
         }
+        $headers['Last-Modified'] = false;
         return $headers;
 }
 
@@ -924 +924 @@
  */
 function nocache_headers() {
         $headers = wp_get_nocache_headers();
+
+        unset( $headers['Last-Modified'] );
+
+        // In PHP 5.3+, make sure we are not sending a Last-Modified header.
+        if ( function_exists( 'header_remove' ) ) {
+                @header_remove( 'Last-Modified' );
+        } else {
+                // In PHP 5.2, send an empty Last-Modified header, but only as a
+                // last resort to override a header already sent. #WP23021
+                foreach ( headers_list() as $header ) {
+                        if ( 0 === stripos( $header, 'Last-Modified' ) ) {
+                                $headers['Last-Modified'] = '';
+                                break;
+                        }
+                }
+        }
+
         foreach( $headers as $name => $field_value )
                 @header("{$name}: {$field_value}");
-        if ( empty( $headers['Last-Modified'] ) && function_exists( 'header_remove' ) )
-                @header_remove( 'Last-Modified' );
 }
 
 /**

wp-includes/class-wp.php

@@ -378 +378 @@
 
                 if ( ! empty( $status ) )
                         status_header( $status );
+
+                // If Last-Modified is set to false, it should not be sent (no-cache situation).
+                if ( isset( $headers['Last-Modified'] ) && false === $headers['Last-Modified'] ) {
+                        unset( $headers['Last-Modified'] );
+
+                        // In PHP 5.3+, make sure we are not sending a Last-Modified header.
+                        if ( function_exists( 'header_remove' ) ) {
+                                @header_remove( 'Last-Modified' );
+                        } else {
+                                // In PHP 5.2, send an empty Last-Modified header, but only as a
+                                // last resort to override a header already sent. #WP23021
+                                foreach ( headers_list() as $header ) {
+                                        if ( 0 === stripos( $header, 'Last-Modified' ) ) {
+                                                $headers['Last-Modified'] = '';
+                                                break;
+                                        }
+                                }
+                        }
+                }
+
                 foreach( (array) $headers as $name => $field_value )
                         @header("{$name}: {$field_value}");
 
-                if ( isset( $headers['Last-Modified'] ) && empty( $headers['Last-Modified'] ) && function_exists( 'header_remove' ) )
-                        @header_remove( 'Last-Modified' );
-
                 if ( $exit_required )
                         exit();