From 6558e5c509036f035c5c5032e5e93d19fb874a0a Mon Sep 17 00:00:00 2001
From: umorigu <umorigu@gmail.com>
Date: Mon, 22 Feb 2016 05:27:22 +0900
Subject: [PATCH] BugTrack2/361 Send Canonical URL link http header for Search
 Engines

---
 lib/html.php | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/html.php b/lib/html.php
index d6eb24d..6b2fc6c 100644
--- a/lib/html.php
+++ b/lib/html.php
@@ -48,6 +48,12 @@ function catbody($title, $page, $body)
 	$_page  = isset($vars['page']) ? $vars['page'] : '';
 	$r_page = pagename_urlencode($_page);
 
+	// Canonical URL
+	$canonical_url = $script;
+	if ($_page !== $defaultpage) {
+		$canonical_url = $script . '?' . $r_page;
+	}
+
 	// Set $_LINK for skin
 	$_LINK['add']      = "$script?cmd=add&amp;page=$r_page";
 	$_LINK['backup']   = "$script?cmd=backup&amp;page=$r_page";
@@ -61,7 +67,7 @@ function catbody($title, $page, $body)
 	$_LINK['new']      = "$script?plugin=newpage&amp;refer=$r_page";
 	$_LINK['rdf']      = "$script?cmd=rss&amp;ver=1.0";
 	$_LINK['recent']   = "$script?" . pagename_urlencode($whatsnew);
-	$_LINK['reload']   = "$script?$r_page";
+	$_LINK['reload']   = $canonical_url;
 	$_LINK['rename']   = "$script?plugin=rename&amp;refer=$r_page";
 	$_LINK['rss']      = "$script?cmd=rss";
 	$_LINK['rss10']    = "$script?cmd=rss&amp;ver=1.0"; // Same as 'rdf'
@@ -140,6 +146,11 @@ function catbody($title, $page, $body)
 		}
 	}
 
+	// Send Canonical URL for Search Engine Optimization
+	if ($is_read && !headers_sent()) {
+		header("Link: <$canonical_url>; rel=\"canonical\"");
+	}
+
 	// Search words
 	if ($search_word_color && isset($vars['word'])) {
 		$body = '<div class="small">' . $_msg_word . htmlsc($vars['word']) .
-- 
2.11.0