Take redirect modifications into account for If-Modified-Since

When the pageview is following a redirect, MediaWiki is only considering
the page_touched timestamp for the target page. This causes issues with
handling If-Modified-Since if the redirect is retargeted after the
target page was last touched.

The simple solution is to use the maximum page_touched of the page or
the redirect (or any other redirect in the chain, if
$wgMaxRedirects > 1).

Bug: 67849
Change-Id: Ia359aaff6eab34c1d609254055c122a644fa7cce

diff --git a/includes/page/Article.php b/includes/page/Article.php
index 0e989d3..2f27826 100644 (file)
--- a/includes/page/Article.php
+++ b/includes/page/Article.php
@@ -480,7 +480,7 @@ class Article implements Page {
         * page of the given title.
         */
        public function view() {
-               global $wgUseFileCache, $wgUseETag, $wgDebugToolbar;
+               global $wgUseFileCache, $wgUseETag, $wgDebugToolbar, $wgMaxRedirects;
 
                wfProfileIn( __METHOD__ );
 
@@ -542,8 +542,31 @@ class Article implements Page {
                                $outputPage->setETag( $parserCache->getETag( $this, $parserOptions ) );
                        }
 
+                       # Use the greatest of the page's timestamp or the timestamp of any
+                       # redirect in the chain (bug 67849)
+                       $timestamp = $this->mPage->getTouched();
+                       if ( isset( $this->mRedirectedFrom ) ) {
+                               $timestamp = max( $timestamp, $this->mRedirectedFrom->getTouched() );
+
+                               # If there can be more than one redirect in the chain, we have
+                               # to go through the whole chain too in case an intermediate
+                               # redirect was changed.
+                               if ( $wgMaxRedirects > 1 ) {
+                                       $titles = Revision::newFromTitle( $this->mRedirectedFrom )
+                                               ->getContent( Revision::FOR_THIS_USER, $user )
+                                               ->getRedirectChain();
+                                       $thisTitle = $this->getTitle();
+                                       foreach ( $titles as $title ) {
+                                               if ( Title::compare( $title, $thisTitle ) === 0 ) {
+                                                       break;
+                                               }
+                                               $timestamp = max( $timestamp, $title->getTouched() );
+                                       }
+                               }
+                       }
+
                        # Is it client cached?
-                       if ( $outputPage->checkLastModified( $this->mPage->getTouched() ) ) {
+                       if ( $outputPage->checkLastModified( $timestamp ) ) {
                                wfDebug( __METHOD__ . ": done 304\n" );
                                wfProfileOut( __METHOD__ );