From 6258e5e55cd78e4f5c9e1a4d27430e48340752f1 Mon Sep 17 00:00:00 2001
From: "C. Scott Ananian" <cscott@cscott.net>
Date: Fri, 12 Oct 2018 11:50:14 -0400
Subject: [PATCH] Deprecate $wgUseKeyHeader and OutputPage::getKeyHeader()

The `Key` header was a draft IETF specification which expired without
becoming a standard.  It does not appear to be in active use anywhere.

Change-Id: I3924a1b5ff428b107573d2827c40e4af8adaaeb1
---
 RELEASE-NOTES-1.32                        |  3 +++
 includes/DefaultSettings.php              |  3 ++-
 includes/OutputPage.php                   | 14 ++++++++++++++
 tests/phpunit/includes/OutputPageTest.php |  3 +++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/RELEASE-NOTES-1.32 b/RELEASE-NOTES-1.32
index 40dd295463..a63a16d293 100644
--- a/RELEASE-NOTES-1.32
+++ b/RELEASE-NOTES-1.32
@@ -531,6 +531,9 @@ because of Phabricator reports.
 * In Skin::doEditSectionLink omitting the parameters $tooltip and $lang is
   deprecated. For the $lang parameter, types other than Language are
   deprecated.
+* The $wgUseKeyHeader configuration option and the
+  OutputPage::getKeyHeader() method have been deprecated; the relevant
+  draft IETF spec expired without becoming a standard.
 
 === Other changes in 1.32 ===
 * (T198811) The following tables have had their UNIQUE indexes turned into
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 4ed17074d4..6a1ed925da 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -2741,8 +2741,9 @@ $wgUseESI = false;
 
 /**
  * Send the Key HTTP header for better caching.
- * See https://datatracker.ietf.org/doc/draft-fielding-http-key/ for details.
+ * See https://datatracker.ietf.org/doc/draft-ietf-httpbis-key/ for details.
  * @since 1.27
+ * @deprecated in 1.32, the IETF spec expired without becoming a standard.
  */
 $wgUseKeyHeader = false;
 
diff --git a/includes/OutputPage.php b/includes/OutputPage.php
index 17e92cbfea..cde92e8c17 100644
--- a/includes/OutputPage.php
+++ b/includes/OutputPage.php
@@ -2281,8 +2281,12 @@ class OutputPage extends ContextSource {
 	 * Get a complete Key header
 	 *
 	 * @return string
+	 * @deprecated in 1.32; the IETF spec for this header expired w/o becoming
+	 *   a standard.
 	 */
 	public function getKeyHeader() {
+		wfDeprecated( '$wgUseKeyHeader', '1.32' );
+
 		$cvCookies = $this->getCacheVaryCookies();
 
 		$cookiesOption = [];
@@ -2330,6 +2334,16 @@ class OutputPage extends ContextSource {
 					continue;
 				}
 
+				// XXX Note that this code is not strictly correct: we
+				// do a case-insensitive match in
+				// LanguageConverter::getHeaderVariant() while the
+				// (abandoned, draft) spec for the `Key` header only
+				// allows case-sensitive matches.  To match the logic
+				// in LanguageConverter::getHeaderVariant() we should
+				// also be looking at fallback variants and deprecated
+				// mediawiki-internal codes, as well as BCP 47
+				// normalized forms.
+
 				$aloption[] = "substr=$variant";
 
 				// IE and some other browsers use BCP 47 standards in their Accept-Language header,
diff --git a/tests/phpunit/includes/OutputPageTest.php b/tests/phpunit/includes/OutputPageTest.php
index 19494f2dfa..53e6f464c9 100644
--- a/tests/phpunit/includes/OutputPageTest.php
+++ b/tests/phpunit/includes/OutputPageTest.php
@@ -2083,6 +2083,7 @@ class OutputPageTest extends MediaWikiTestCase {
 			->will( $this->returnValue( $cookies ) );
 		TestingAccessWrapper::newFromObject( $op )->mVaryHeader = [];
 
+		$this->hideDeprecated( '$wgUseKeyHeader' );
 		foreach ( $calls as $call ) {
 			$op->addVaryHeader( ...$call );
 		}
@@ -2235,6 +2236,7 @@ class OutputPageTest extends MediaWikiTestCase {
 	/**
 	 * @dataProvider provideAddAcceptLanguage
 	 * @covers OutputPage::addAcceptLanguage
+	 * @covers OutputPage::getKeyHeader
 	 */
 	public function testAddAcceptLanguage(
 		$code, array $variants, array $expected, array $options = []
@@ -2262,6 +2264,7 @@ class OutputPageTest extends MediaWikiTestCase {
 		// This will run addAcceptLanguage()
 		$op->sendCacheControl();
 
+		$this->hideDeprecated( '$wgUseKeyHeader' );
 		$keyHeader = $op->getKeyHeader();
 
 		if ( !$expected ) {
-- 
2.20.1