1 files changed, 69 insertions, 0 deletions
diff --git a/www/wiki/includes/HeaderCallback.php b/www/wiki/includes/HeaderCallback.php
new file mode 100644
index 00000000..b2ca6733
--- /dev/null
+++ b/www/wiki/includes/HeaderCallback.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace MediaWiki;
+
+class HeaderCallback {
+	private static $headersSentException;
+	private static $messageSent = false;
+
+	/**
+	 * Register a callback to be called when headers are sent. There can only
+	 * be one of these handlers active, so all relevant actions have to be in
+	 * here.
+	 */
+	public static function register() {
+		header_register_callback( [ __CLASS__, 'callback' ] );
+	}
+
+	/**
+	 * The callback, which is called by the transport
+	 */
+	public static function callback() {
+		// Prevent caching of responses with cookies (T127993)
+		$headers = [];
+		foreach ( headers_list() as $header ) {
+			list( $name, $value ) = explode( ':', $header, 2 );
+			$headers[strtolower( trim( $name ) )][] = trim( $value );
+		}
+
+		if ( isset( $headers['set-cookie'] ) ) {
+			$cacheControl = isset( $headers['cache-control'] )
+				? implode( ', ', $headers['cache-control'] )
+				: '';
+
+			if ( !preg_match( '/(?:^|,)\s*(?:private|no-cache|no-store)\s*(?:$|,)/i',
+				$cacheControl )
+			) {
+				header( 'Expires: Thu, 01 Jan 1970 00:00:00 GMT' );
+				header( 'Cache-Control: private, max-age=0, s-maxage=0' );
+				\MediaWiki\Logger\LoggerFactory::getInstance( 'cache-cookies' )->warning(
+					'Cookies set on {url} with Cache-Control "{cache-control}"', [
+						'url' => \WebRequest::getGlobalRequestURL(),
+						'cookies' => $headers['set-cookie'],
+						'cache-control' => $cacheControl ?: '<not set>',
+					]
+				);
+			}
+		}
+
+		// Save a backtrace for logging in case it turns out that headers were sent prematurely
+		self::$headersSentException = new \Exception( 'Headers already sent from this point' );
+	}
+
+	/**
+	 * Log a warning message if headers have already been sent. This can be
+	 * called before flushing the output.
+	 */
+	public static function warnIfHeadersSent() {
+		if ( headers_sent() && !self::$messageSent ) {
+			self::$messageSent = true;
+			\MWDebug::warning( 'Headers already sent, should send headers earlier than ' .
+				wfGetCaller( 3 ) );
+			$logger = \MediaWiki\Logger\LoggerFactory::getInstance( 'headers-sent' );
+			$logger->error( 'Warning: headers were already sent from the location below', [
+				'exception' => self::$headersSentException,
+				'detection-trace' => new \Exception( 'Detected here' ),
+			] );
+		}
+	}
+}