AjaxResponse.php

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<?php
use MediaWiki\MediaWikiServices;
 
class AjaxResponse {
    private $mCacheDuration;
 
    private $mContentType;
 
    private $mDisabled;
 
    private $mLastModified;
 
    private $mResponseCode;
 
    private $mVary;
 
    private $mText;
 
    private $mConfig;
 
    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 );
        }
    }
 
    function setCacheDuration( $duration ) {
        $this->mCacheDuration = $duration;
    }
 
    function setVary( $vary ) {
        $this->mVary = $vary;
    }
 
    function setResponseCode( $code ) {
        $this->mResponseCode = $code;
    }
 
    function setContentType( $type ) {
        $this->mContentType = $type;
    }
 
    function disable() {
        $this->mDisabled = true;
    }
 
    function addText( $text ) {
        if ( !$this->mDisabled && $text ) {
            $this->mText .= $text;
        }
    }
 
    function printText() {
        if ( !$this->mDisabled ) {
            print $this->mText;
        }
    }
 
    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 );
        }
    }
 
    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, $modsinceTime ?: 1 );
            wfDebug( "$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;
    }
 
    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;
    }
 
    function storeInMemcached( $mckey, $expiry = 86400 ) {
        ObjectCache::getMainWANInstance()->set( $mckey,
            [
                'timestamp' => wfTimestampNow(),
                'value' => $this->mText
            ], $expiry
        );
 
        return true;
    }
}