1 files changed, 269 insertions, 0 deletions
diff --git a/www/wiki/includes/libs/filebackend/HTTPFileStreamer.php b/www/wiki/includes/libs/filebackend/HTTPFileStreamer.php
new file mode 100644
index 00000000..9f8959cb
--- /dev/null
+++ b/www/wiki/includes/libs/filebackend/HTTPFileStreamer.php
@@ -0,0 +1,269 @@
+<?php
+/**
+ * Functions related to the output of file content.
+ *
+ * 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
+ */
+use Wikimedia\Timestamp\ConvertibleTimestamp;
+
+/**
+ * Functions related to the output of file content
+ *
+ * @since 1.28
+ */
+class HTTPFileStreamer {
+	/** @var string */
+	protected $path;
+	/** @var callable */
+	protected $obResetFunc;
+	/** @var callable */
+	protected $streamMimeFunc;
+
+	// Do not send any HTTP headers unless requested by caller (e.g. body only)
+	const STREAM_HEADLESS = 1;
+	// Do not try to tear down any PHP output buffers
+	const STREAM_ALLOW_OB = 2;
+
+	/**
+	 * @param string $path Local filesystem path to a file
+	 * @param array $params Options map, which includes:
+	 *   - obResetFunc : alternative callback to clear the output buffer
+	 *   - streamMimeFunc : alternative method to determine the content type from the path
+	 */
+	public function __construct( $path, array $params = [] ) {
+		$this->path = $path;
+		$this->obResetFunc = isset( $params['obResetFunc'] )
+			? $params['obResetFunc']
+			: [ __CLASS__, 'resetOutputBuffers' ];
+		$this->streamMimeFunc = isset( $params['streamMimeFunc'] )
+			? $params['streamMimeFunc']
+			: [ __CLASS__, 'contentTypeFromPath' ];
+	}
+
+	/**
+	 * Stream a file to the browser, adding all the headings and fun stuff.
+	 * Headers sent include: Content-type, Content-Length, Last-Modified,
+	 * and Content-Disposition.
+	 *
+	 * @param array $headers Any additional headers to send if the file exists
+	 * @param bool $sendErrors Send error messages if errors occur (like 404)
+	 * @param array $optHeaders HTTP request header map (e.g. "range") (use lowercase keys)
+	 * @param int $flags Bitfield of STREAM_* constants
+	 * @throws MWException
+	 * @return bool Success
+	 */
+	public function stream(
+		$headers = [], $sendErrors = true, $optHeaders = [], $flags = 0
+	) {
+		// Don't stream it out as text/html if there was a PHP error
+		if ( ( ( $flags & self::STREAM_HEADLESS ) == 0 || $headers ) && headers_sent() ) {
+			echo "Headers already sent, terminating.\n";
+			return false;
+		}
+
+		$headerFunc = ( $flags & self::STREAM_HEADLESS )
+			? function ( $header ) {
+				// no-op
+			}
+			: function ( $header ) {
+				is_int( $header ) ? HttpStatus::header( $header ) : header( $header );
+			};
+
+		Wikimedia\suppressWarnings();
+		$info = stat( $this->path );
+		Wikimedia\restoreWarnings();
+
+		if ( !is_array( $info ) ) {
+			if ( $sendErrors ) {
+				self::send404Message( $this->path, $flags );
+			}
+			return false;
+		}
+
+		// Send Last-Modified HTTP header for client-side caching
+		$mtimeCT = new ConvertibleTimestamp( $info['mtime'] );
+		$headerFunc( 'Last-Modified: ' . $mtimeCT->getTimestamp( TS_RFC2822 ) );
+
+		if ( ( $flags & self::STREAM_ALLOW_OB ) == 0 ) {
+			call_user_func( $this->obResetFunc );
+		}
+
+		$type = call_user_func( $this->streamMimeFunc, $this->path );
+		if ( $type && $type != 'unknown/unknown' ) {
+			$headerFunc( "Content-type: $type" );
+		} else {
+			// Send a content type which is not known to Internet Explorer, to
+			// avoid triggering IE's content type detection. Sending a standard
+			// unknown content type here essentially gives IE license to apply
+			// whatever content type it likes.
+			$headerFunc( 'Content-type: application/x-wiki' );
+		}
+
+		// Don't send if client has up to date cache
+		if ( isset( $optHeaders['if-modified-since'] ) ) {
+			$modsince = preg_replace( '/;.*$/', '', $optHeaders['if-modified-since'] );
+			if ( $mtimeCT->getTimestamp( TS_UNIX ) <= strtotime( $modsince ) ) {
+				ini_set( 'zlib.output_compression', 0 );
+				$headerFunc( 304 );
+				return true; // ok
+			}
+		}
+
+		// Send additional headers
+		foreach ( $headers as $header ) {
+			header( $header ); // always use header(); specifically requested
+		}
+
+		if ( isset( $optHeaders['range'] ) ) {
+			$range = self::parseRange( $optHeaders['range'], $info['size'] );
+			if ( is_array( $range ) ) {
+				$headerFunc( 206 );
+				$headerFunc( 'Content-Length: ' . $range[2] );
+				$headerFunc( "Content-Range: bytes {$range[0]}-{$range[1]}/{$info['size']}" );
+			} elseif ( $range === 'invalid' ) {
+				if ( $sendErrors ) {
+					$headerFunc( 416 );
+					$headerFunc( 'Cache-Control: no-cache' );
+					$headerFunc( 'Content-Type: text/html; charset=utf-8' );
+					$headerFunc( 'Content-Range: bytes */' . $info['size'] );
+				}
+				return false;
+			} else { // unsupported Range request (e.g. multiple ranges)
+				$range = null;
+				$headerFunc( 'Content-Length: ' . $info['size'] );
+			}
+		} else {
+			$range = null;
+			$headerFunc( 'Content-Length: ' . $info['size'] );
+		}
+
+		if ( is_array( $range ) ) {
+			$handle = fopen( $this->path, 'rb' );
+			if ( $handle ) {
+				$ok = true;
+				fseek( $handle, $range[0] );
+				$remaining = $range[2];
+				while ( $remaining > 0 && $ok ) {
+					$bytes = min( $remaining, 8 * 1024 );
+					$data = fread( $handle, $bytes );
+					$remaining -= $bytes;
+					$ok = ( $data !== false );
+					print $data;
+				}
+			} else {
+				return false;
+			}
+		} else {
+			return readfile( $this->path ) !== false; // faster
+		}
+
+		return true;
+	}
+
+	/**
+	 * Send out a standard 404 message for a file
+	 *
+	 * @param string $fname Full name and path of the file to stream
+	 * @param int $flags Bitfield of STREAM_* constants
+	 * @since 1.24
+	 */
+	public static function send404Message( $fname, $flags = 0 ) {
+		if ( ( $flags & self::STREAM_HEADLESS ) == 0 ) {
+			HttpStatus::header( 404 );
+			header( 'Cache-Control: no-cache' );
+			header( 'Content-Type: text/html; charset=utf-8' );
+		}
+		$encFile = htmlspecialchars( $fname );
+		$encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
+		echo "<!DOCTYPE html><html><body>
+			<h1>File not found</h1>
+			<p>Although this PHP script ($encScript) exists, the file requested for output
+			($encFile) does not.</p>
+			</body></html>
+			";
+	}
+
+	/**
+	 * Convert a Range header value to an absolute (start, end) range tuple
+	 *
+	 * @param string $range Range header value
+	 * @param int $size File size
+	 * @return array|string Returns error string on failure (start, end, length)
+	 * @since 1.24
+	 */
+	public static function parseRange( $range, $size ) {
+		$m = [];
+		if ( preg_match( '#^bytes=(\d*)-(\d*)$#', $range, $m ) ) {
+			list( , $start, $end ) = $m;
+			if ( $start === '' && $end === '' ) {
+				$absRange = [ 0, $size - 1 ];
+			} elseif ( $start === '' ) {
+				$absRange = [ $size - $end, $size - 1 ];
+			} elseif ( $end === '' ) {
+				$absRange = [ $start, $size - 1 ];
+			} else {
+				$absRange = [ $start, $end ];
+			}
+			if ( $absRange[0] >= 0 && $absRange[1] >= $absRange[0] ) {
+				if ( $absRange[0] < $size ) {
+					$absRange[1] = min( $absRange[1], $size - 1 ); // stop at EOF
+					$absRange[2] = $absRange[1] - $absRange[0] + 1;
+					return $absRange;
+				} elseif ( $absRange[0] == 0 && $size == 0 ) {
+					return 'unrecognized'; // the whole file should just be sent
+				}
+			}
+			return 'invalid';
+		}
+		return 'unrecognized';
+	}
+
+	protected static function resetOutputBuffers() {
+		while ( ob_get_status() ) {
+			if ( !ob_end_clean() ) {
+				// Could not remove output buffer handler; abort now
+				// to avoid getting in some kind of infinite loop.
+				break;
+			}
+		}
+	}
+
+	/**
+	 * Determine the file type of a file based on the path
+	 *
+	 * @param string $filename Storage path or file system path
+	 * @return null|string
+	 */
+	protected static function contentTypeFromPath( $filename ) {
+		$ext = strrchr( $filename, '.' );
+		$ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
+
+		switch ( $ext ) {
+			case 'gif':
+				return 'image/gif';
+			case 'png':
+				return 'image/png';
+			case 'jpg':
+				return 'image/jpeg';
+			case 'jpeg':
+				return 'image/jpeg';
+		}
+
+		return 'unknown/unknown';
+	}
+}