From a4adffd49f5b8edc0f16fb9f52471f0732ba8a3e Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Tue, 15 Mar 2005 03:32:30 +0000
Subject: [PATCH] Mark interwiki redirect URLs with a source parameter to stop
 them from further redirecting, and if on a whitelist display the return URL
 for handy edit-linking.

---
 includes/Article.php         | 17 +++++++++++------
 includes/DefaultSettings.php | 15 +++++++++++++++
 includes/Title.php           |  8 ++++++++
 index.php                    |  6 +++++-
 4 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/includes/Article.php b/includes/Article.php
index 8de243bff4..0c14bd8e30 100644
--- a/includes/Article.php
+++ b/includes/Article.php
@@ -256,7 +256,8 @@ class Article {
 
 		$t = $this->mTitle->getPrefixedText();
 
-		$noredir = $noredir || ($wgRequest->getVal( 'redirect' ) == 'no');
+		$noredir = $noredir || ($wgRequest->getVal( 'redirect' ) == 'no')
+			|| $wgRequest->getCheck( 'rdfrom' );
 		$this->mOldId = $oldid;
 		$this->fetchContent( $oldid, $noredir, true );
 	}
@@ -350,7 +351,8 @@ class Article {
 				if( $globalTitle ) {
 					global $wgOut;
 					if ( $rt->getInterwiki() != '' && $rt->isLocal() ) {
-						$wgOut->redirect( $rt->getFullURL() ) ;
+						$source = $this->mTitle->getFullURL( 'redirect=no' );
+						$wgOut->redirect( $rt->getFullURL( 'rdfrom=' . urlencode( $source ) ) ) ;
 						return false;
 					}
 					if ( $rt->getNamespace() == NS_SPECIAL ) {
@@ -670,10 +672,13 @@ class Article {
 				# Can't cache redirects
 				$pcache = false;
 			} elseif ( !empty( $rdfrom ) ) {
-				$sk = $wgUser->getSkin();
-				$redir = $sk->makeExternalLink( $rdfrom, $rdfrom );
-				$s = wfMsg( 'redirectedfrom', $redir );
-				$wgOut->setSubtitle( $s );
+				global $wgRedirectSources;
+				if( $wgRedirectSources && preg_match( $wgRedirectSources, $rdfrom ) ) {
+					$sk = $wgUser->getSkin();
+					$redir = $sk->makeExternalLink( $rdfrom, $rdfrom );
+					$s = wfMsg( 'redirectedfrom', $redir );
+					$wgOut->setSubtitle( $s );
+				}
 			}
 
 			# wrap user css and user js in pre and don't parse
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index c36ef056f6..f14fe7e57d 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -402,6 +402,21 @@ $wgZhdaemonPort=2004;
 $wgLocalInterwiki   = 'w';
 $wgInterwikiExpiry = 10800; # Expiry time for cache of interwiki table
 
+/**
+ * If local interwikis are set up which allow redirects,
+ * set this regexp to restrict URLs which will be displayed
+ * as 'redirected from' links.
+ *
+ * It might look something like this:
+ * $wgRedirectSources = '!^https?://[a-z-]+\.wikipedia\.org/!';
+ *
+ * Leave at false to avoid displaying any incoming redirect markers.
+ * This does not affect intra-wiki redirects, which don't change
+ * the URL.
+ */
+$wgRedirectSources = false;
+
+
 $wgShowIPinHeader	= true; # For non-logged in users
 $wgMaxNameChars     = 32; # Maximum number of bytes in username
 
diff --git a/includes/Title.php b/includes/Title.php
index 95ee0176c4..fe03907537 100644
--- a/includes/Title.php
+++ b/includes/Title.php
@@ -629,6 +629,14 @@ class Title {
 				$namepace .= ':';
 			}
 			$url = str_replace( '$1', $namespace . $this->mUrlform, $baseUrl );
+			if( $query != '' ) {
+				if( false === strpos( $url, '?' ) ) {
+					$url .= '?';
+				} else {
+					$url .= '&';
+				}
+				$url .= $query;
+			}
 			if ( '' != $this->mFragment ) {
 				$url .= '#' . $this->mFragment;
 			}
diff --git a/index.php b/index.php
index ec627961cb..0c77aec93e 100644
--- a/index.php
+++ b/index.php
@@ -76,7 +76,11 @@ if( !$wgDisableInternalSearch && !is_null( $search ) && $search !== '' ) {
 		$interwiki = Title::newFromUrl( $_REQUEST['title'] );
 		if( !is_null( $interwiki ) ) $wgTitle = $interwiki;
 	}
-	$url = $wgTitle->getFullURL();
+	if( $rdfrom = $wgRequest->getVal( 'rdfrom' ) ) {
+		$url = $wgTitle->getFullURL( 'rdfrom=' . urlencode( $rdfrom ) );
+	} else {
+		$url = $wgTitle->getFullURL();
+	}
 	# Check for a redirect loop
 	if ( !preg_match( '/^' . preg_quote( $wgServer, '/' ) . '/', $url ) && $wgTitle->isLocal() ) {
 		$wgOut->redirect( $url );
-- 
2.20.1