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diff --git a/www/wiki/includes/AjaxResponse.php b/www/wiki/includes/AjaxResponse.php
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+<?php
+/**
+ * Response handler for Ajax requests.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Ajax
+ */
+use MediaWiki\MediaWikiServices;
+
+/**
+ * Handle responses for Ajax requests (send headers, print
+ * content, that sort of thing)
+ *
+ * @ingroup Ajax
+ */
+class AjaxResponse {
+	/**
+	 * Number of seconds to get the response cached by a proxy
+	 * @var int $mCacheDuration
+	 */
+	private $mCacheDuration;
+
+	/**
+	 * HTTP header Content-Type
+	 * @var string $mContentType
+	 */
+	private $mContentType;
+
+	/**
+	 * Disables output. Can be set by calling $AjaxResponse->disable()
+	 * @var bool $mDisabled
+	 */
+	private $mDisabled;
+
+	/**
+	 * Date for the HTTP header Last-modified
+	 * @var string|bool $mLastModified
+	 */
+	private $mLastModified;
+
+	/**
+	 * HTTP response code
+	 * @var string $mResponseCode
+	 */
+	private $mResponseCode;
+
+	/**
+	 * HTTP Vary header
+	 * @var string $mVary
+	 */
+	private $mVary;
+
+	/**
+	 * Content of our HTTP response
+	 * @var string $mText
+	 */
+	private $mText;
+
+	/**
+	 * @var Config
+	 */
+	private $mConfig;
+
+	/**
+	 * @param string|null $text
+	 * @param Config|null $config
+	 */
+	function __construct( $text = null, Config $config = null ) {
+		$this->mCacheDuration = null;
+		$this->mVary = null;
+		$this->mConfig = $config ?: MediaWikiServices::getInstance()->getMainConfig();
+
+		$this->mDisabled = false;
+		$this->mText = '';
+		$this->mResponseCode = 200;
+		$this->mLastModified = false;
+		$this->mContentType = 'application/x-wiki';
+
+		if ( $text ) {
+			$this->addText( $text );
+		}
+	}
+
+	/**
+	 * Set the number of seconds to get the response cached by a proxy
+	 * @param int $duration
+	 */
+	function setCacheDuration( $duration ) {
+		$this->mCacheDuration = $duration;
+	}
+
+	/**
+	 * Set the HTTP Vary header
+	 * @param string $vary
+	 */
+	function setVary( $vary ) {
+		$this->mVary = $vary;
+	}
+
+	/**
+	 * Set the HTTP response code
+	 * @param string $code
+	 */
+	function setResponseCode( $code ) {
+		$this->mResponseCode = $code;
+	}
+
+	/**
+	 * Set the HTTP header Content-Type
+	 * @param string $type
+	 */
+	function setContentType( $type ) {
+		$this->mContentType = $type;
+	}
+
+	/**
+	 * Disable output.
+	 */
+	function disable() {
+		$this->mDisabled = true;
+	}
+
+	/**
+	 * Add content to the response
+	 * @param string $text
+	 */
+	function addText( $text ) {
+		if ( !$this->mDisabled && $text ) {
+			$this->mText .= $text;
+		}
+	}
+
+	/**
+	 * Output text
+	 */
+	function printText() {
+		if ( !$this->mDisabled ) {
+			print $this->mText;
+		}
+	}
+
+	/**
+	 * Construct the header and output it
+	 */
+	function sendHeaders() {
+		if ( $this->mResponseCode ) {
+			// For back-compat, it is supported that mResponseCode be a string like " 200 OK"
+			// (with leading space and the status message after). Cast response code to an integer
+			// to take advantage of PHP's conversion rules which will turn "  200 OK" into 200.
+			// https://secure.php.net/manual/en/language.types.string.php#language.types.string.conversion
+			$n = intval( trim( $this->mResponseCode ) );
+			HttpStatus::header( $n );
+		}
+
+		header( "Content-Type: " . $this->mContentType );
+
+		if ( $this->mLastModified ) {
+			header( "Last-Modified: " . $this->mLastModified );
+		} else {
+			header( "Last-Modified: " . gmdate( "D, d M Y H:i:s" ) . " GMT" );
+		}
+
+		if ( $this->mCacheDuration ) {
+			# If CDN caches are configured, tell them to cache the response,
+			# and tell the client to always check with the CDN. Otherwise,
+			# tell the client to use a cached copy, without a way to purge it.
+
+			if ( $this->mConfig->get( 'UseSquid' ) ) {
+				# Expect explicit purge of the proxy cache, but require end user agents
+				# to revalidate against the proxy on each visit.
+				# Surrogate-Control controls our CDN, Cache-Control downstream caches
+
+				if ( $this->mConfig->get( 'UseESI' ) ) {
+					header( 'Surrogate-Control: max-age=' . $this->mCacheDuration . ', content="ESI/1.0"' );
+					header( 'Cache-Control: s-maxage=0, must-revalidate, max-age=0' );
+				} else {
+					header( 'Cache-Control: s-maxage=' . $this->mCacheDuration . ', must-revalidate, max-age=0' );
+				}
+
+			} else {
+				# Let the client do the caching. Cache is not purged.
+				header( "Expires: " . gmdate( "D, d M Y H:i:s", time() + $this->mCacheDuration ) . " GMT" );
+				header( "Cache-Control: s-maxage={$this->mCacheDuration}," .
+					"public,max-age={$this->mCacheDuration}" );
+			}
+
+		} else {
+			# always expired, always modified
+			header( "Expires: Mon, 26 Jul 1997 05:00:00 GMT" );    // Date in the past
+			header( "Cache-Control: no-cache, must-revalidate" );  // HTTP/1.1
+			header( "Pragma: no-cache" );                          // HTTP/1.0
+		}
+
+		if ( $this->mVary ) {
+			header( "Vary: " . $this->mVary );
+		}
+	}
+
+	/**
+	 * checkLastModified tells the client to use the client-cached response if
+	 * possible. If successful, the AjaxResponse is disabled so that
+	 * any future call to AjaxResponse::printText() have no effect.
+	 *
+	 * @param string $timestamp
+	 * @return bool Returns true if the response code was set to 304 Not Modified.
+	 */
+	function checkLastModified( $timestamp ) {
+		global $wgCachePages, $wgCacheEpoch, $wgUser;
+		$fname = 'AjaxResponse::checkLastModified';
+
+		if ( !$timestamp || $timestamp == '19700101000000' ) {
+			wfDebug( "$fname: CACHE DISABLED, NO TIMESTAMP", 'private' );
+			return false;
+		}
+
+		if ( !$wgCachePages ) {
+			wfDebug( "$fname: CACHE DISABLED", 'private' );
+			return false;
+		}
+
+		$timestamp = wfTimestamp( TS_MW, $timestamp );
+		$lastmod = wfTimestamp( TS_RFC2822, max( $timestamp, $wgUser->getTouched(), $wgCacheEpoch ) );
+
+		if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
+			# IE sends sizes after the date like this:
+			# Wed, 20 Aug 2003 06:51:19 GMT; length=5202
+			# this breaks strtotime().
+			$modsince = preg_replace( '/;.*$/', '', $_SERVER["HTTP_IF_MODIFIED_SINCE"] );
+			$modsinceTime = strtotime( $modsince );
+			$ismodsince = wfTimestamp( TS_MW, $modsinceTime ? $modsinceTime : 1 );
+			wfDebug( "$fname: -- client send If-Modified-Since: $modsince", 'private' );
+			wfDebug( "$fname: --  we might send Last-Modified : $lastmod", 'private' );
+
+			if ( ( $ismodsince >= $timestamp )
+				&& $wgUser->validateCache( $ismodsince ) &&
+				$ismodsince >= $wgCacheEpoch
+			) {
+				ini_set( 'zlib.output_compression', 0 );
+				$this->setResponseCode( 304 );
+				$this->disable();
+				$this->mLastModified = $lastmod;
+
+				wfDebug( "$fname: CACHED client: $ismodsince ; user: {$wgUser->getTouched()} ; " .
+					"page: $timestamp ; site $wgCacheEpoch", 'private' );
+
+				return true;
+			} else {
+				wfDebug( "$fname: READY  client: $ismodsince ; user: {$wgUser->getTouched()} ; " .
+					"page: $timestamp ; site $wgCacheEpoch", 'private' );
+				$this->mLastModified = $lastmod;
+			}
+		} else {
+			wfDebug( "$fname: client did not send If-Modified-Since header", 'private' );
+			$this->mLastModified = $lastmod;
+		}
+		return false;
+	}
+
+	/**
+	 * @param string $mckey
+	 * @param int $touched
+	 * @return bool
+	 */
+	function loadFromMemcached( $mckey, $touched ) {
+		if ( !$touched ) {
+			return false;
+		}
+
+		$mcvalue = ObjectCache::getMainWANInstance()->get( $mckey );
+		if ( $mcvalue ) {
+			# Check to see if the value has been invalidated
+			if ( $touched <= $mcvalue['timestamp'] ) {
+				wfDebug( "Got $mckey from cache" );
+				$this->mText = $mcvalue['value'];
+
+				return true;
+			} else {
+				wfDebug( "$mckey has expired" );
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param string $mckey
+	 * @param int $expiry
+	 * @return bool
+	 */
+	function storeInMemcached( $mckey, $expiry = 86400 ) {
+		ObjectCache::getMainWANInstance()->set( $mckey,
+			[
+				'timestamp' => wfTimestampNow(),
+				'value' => $this->mText
+			], $expiry
+		);
+
+		return true;
+	}
+}