includes/libs/filebackend/HTTPFileStreamer.php

   1 <?php
   2 /**
   3  * Functions related to the output of file content.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 use Wikimedia\AtEase\AtEase;
  24 use Wikimedia\Timestamp\ConvertibleTimestamp;
  25
  26 /**
  27  * Functions related to the output of file content
  28  *
  29  * @since 1.28
  30  */
  31 class HTTPFileStreamer {
  32         /** @var string */
  33         protected $path;
  34         /** @var callable */
  35         protected $obResetFunc;
  36         /** @var callable */
  37         protected $streamMimeFunc;
  38
  39         // Do not send any HTTP headers unless requested by caller (e.g. body only)
  40         const STREAM_HEADLESS = 1;
  41         // Do not try to tear down any PHP output buffers
  42         const STREAM_ALLOW_OB = 2;
  43
  44         /**
  45          * Takes HTTP headers in a name => value format and converts them to the weird format
  46          * expected by stream().
  47          * @param string[] $headers
  48          * @return array[] [ $headers, $optHeaders ]
  49          * @since 1.34
  50          */
  51         public static function preprocessHeaders( $headers ) {
  52                 $rawHeaders = [];
  53                 $optHeaders = [];
  54                 foreach ( $headers as $name => $header ) {
  55                         $nameLower = strtolower( $name );
  56                         if ( in_array( $nameLower, [ 'range', 'if-modified-since' ], true ) ) {
  57                                 $optHeaders[$nameLower] = $header;
  58                         } else {
  59                                 $rawHeaders[] = "$name: $header";
  60                         }
  61                 }
  62                 return [ $rawHeaders, $optHeaders ];
  63         }
  64
  65         /**
  66          * @param string $path Local filesystem path to a file
  67          * @param array $params Options map, which includes:
  68          *   - obResetFunc : alternative callback to clear the output buffer
  69          *   - streamMimeFunc : alternative method to determine the content type from the path
  70          */
  71         public function __construct( $path, array $params = [] ) {
  72                 $this->path = $path;
  73                 $this->obResetFunc = $params['obResetFunc'] ?? [ __CLASS__, 'resetOutputBuffers' ];
  74                 $this->streamMimeFunc = $params['streamMimeFunc'] ?? [ __CLASS__, 'contentTypeFromPath' ];
  75         }
  76
  77         /**
  78          * Stream a file to the browser, adding all the headings and fun stuff.
  79          * Headers sent include: Content-type, Content-Length, Last-Modified,
  80          * and Content-Disposition.
  81          *
  82          * @param array $headers Any additional headers to send if the file exists
  83          * @param bool $sendErrors Send error messages if errors occur (like 404)
  84          * @param array $optHeaders HTTP request header map (e.g. "range") (use lowercase keys)
  85          * @param int $flags Bitfield of STREAM_* constants
  86          * @return bool Success
  87          */
  88         public function stream(
  89                 $headers = [], $sendErrors = true, $optHeaders = [], $flags = 0
  90         ) {
  91                 // Don't stream it out as text/html if there was a PHP error
  92                 if ( ( ( $flags & self::STREAM_HEADLESS ) == 0 || $headers ) && headers_sent() ) {
  93                         echo "Headers already sent, terminating.\n";
  94                         return false;
  95                 }
  96
  97                 $headerFunc = ( $flags & self::STREAM_HEADLESS )
  98                         ? function ( $header ) {
  99                                 // no-op
 100                         }
 101                         : function ( $header ) {
 102                                 is_int( $header ) ? HttpStatus::header( $header ) : header( $header );
 103                         };
 104
 105                 AtEase::suppressWarnings();
 106                 $info = stat( $this->path );
 107                 AtEase::restoreWarnings();
 108
 109                 if ( !is_array( $info ) ) {
 110                         if ( $sendErrors ) {
 111                                 self::send404Message( $this->path, $flags );
 112                         }
 113                         return false;
 114                 }
 115
 116                 // Send Last-Modified HTTP header for client-side caching
 117                 $mtimeCT = new ConvertibleTimestamp( $info['mtime'] );
 118                 $headerFunc( 'Last-Modified: ' . $mtimeCT->getTimestamp( TS_RFC2822 ) );
 119
 120                 if ( ( $flags & self::STREAM_ALLOW_OB ) == 0 ) {
 121                         call_user_func( $this->obResetFunc );
 122                 }
 123
 124                 $type = call_user_func( $this->streamMimeFunc, $this->path );
 125                 if ( $type && $type != 'unknown/unknown' ) {
 126                         $headerFunc( "Content-type: $type" );
 127                 } else {
 128                         // Send a content type which is not known to Internet Explorer, to
 129                         // avoid triggering IE's content type detection. Sending a standard
 130                         // unknown content type here essentially gives IE license to apply
 131                         // whatever content type it likes.
 132                         $headerFunc( 'Content-type: application/x-wiki' );
 133                 }
 134
 135                 // Don't send if client has up to date cache
 136                 if ( isset( $optHeaders['if-modified-since'] ) ) {
 137                         $modsince = preg_replace( '/;.*$/', '', $optHeaders['if-modified-since'] );
 138                         if ( $mtimeCT->getTimestamp( TS_UNIX ) <= strtotime( $modsince ) ) {
 139                                 ini_set( 'zlib.output_compression', 0 );
 140                                 $headerFunc( 304 );
 141                                 return true; // ok
 142                         }
 143                 }
 144
 145                 // Send additional headers
 146                 foreach ( $headers as $header ) {
 147                         header( $header ); // always use header(); specifically requested
 148                 }
 149
 150                 if ( isset( $optHeaders['range'] ) ) {
 151                         $range = self::parseRange( $optHeaders['range'], $info['size'] );
 152                         if ( is_array( $range ) ) {
 153                                 $headerFunc( 206 );
 154                                 $headerFunc( 'Content-Length: ' . $range[2] );
 155                                 $headerFunc( "Content-Range: bytes {$range[0]}-{$range[1]}/{$info['size']}" );
 156                         } elseif ( $range === 'invalid' ) {
 157                                 if ( $sendErrors ) {
 158                                         $headerFunc( 416 );
 159                                         $headerFunc( 'Cache-Control: no-cache' );
 160                                         $headerFunc( 'Content-Type: text/html; charset=utf-8' );
 161                                         $headerFunc( 'Content-Range: bytes */' . $info['size'] );
 162                                 }
 163                                 return false;
 164                         } else { // unsupported Range request (e.g. multiple ranges)
 165                                 $range = null;
 166                                 $headerFunc( 'Content-Length: ' . $info['size'] );
 167                         }
 168                 } else {
 169                         $range = null;
 170                         $headerFunc( 'Content-Length: ' . $info['size'] );
 171                 }
 172
 173                 if ( is_array( $range ) ) {
 174                         $handle = fopen( $this->path, 'rb' );
 175                         if ( $handle ) {
 176                                 $ok = true;
 177                                 fseek( $handle, $range[0] );
 178                                 $remaining = $range[2];
 179                                 while ( $remaining > 0 && $ok ) {
 180                                         $bytes = min( $remaining, 8 * 1024 );
 181                                         $data = fread( $handle, $bytes );
 182                                         $remaining -= $bytes;
 183                                         $ok = ( $data !== false );
 184                                         print $data;
 185                                 }
 186                         } else {
 187                                 return false;
 188                         }
 189                 } else {
 190                         return readfile( $this->path ) !== false; // faster
 191                 }
 192
 193                 return true;
 194         }
 195
 196         /**
 197          * Send out a standard 404 message for a file
 198          *
 199          * @param string $fname Full name and path of the file to stream
 200          * @param int $flags Bitfield of STREAM_* constants
 201          * @since 1.24
 202          */
 203         public static function send404Message( $fname, $flags = 0 ) {
 204                 if ( ( $flags & self::STREAM_HEADLESS ) == 0 ) {
 205                         HttpStatus::header( 404 );
 206                         header( 'Cache-Control: no-cache' );
 207                         header( 'Content-Type: text/html; charset=utf-8' );
 208                 }
 209                 $encFile = htmlspecialchars( $fname );
 210                 $encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
 211                 echo "<!DOCTYPE html><html><body>
 212                         <h1>File not found</h1>
 213                         <p>Although this PHP script ($encScript) exists, the file requested for output
 214                         ($encFile) does not.</p>
 215                         </body></html>
 216                         ";
 217         }
 218
 219         /**
 220          * Convert a Range header value to an absolute (start, end) range tuple
 221          *
 222          * @param string $range Range header value
 223          * @param int $size File size
 224          * @return array|string Returns error string on failure (start, end, length)
 225          * @since 1.24
 226          */
 227         public static function parseRange( $range, $size ) {
 228                 $m = [];
 229                 if ( preg_match( '#^bytes=(\d*)-(\d*)$#', $range, $m ) ) {
 230                         list( , $start, $end ) = $m;
 231                         if ( $start === '' && $end === '' ) {
 232                                 $absRange = [ 0, $size - 1 ];
 233                         } elseif ( $start === '' ) {
 234                                 $absRange = [ $size - $end, $size - 1 ];
 235                         } elseif ( $end === '' ) {
 236                                 $absRange = [ $start, $size - 1 ];
 237                         } else {
 238                                 $absRange = [ $start, $end ];
 239                         }
 240                         if ( $absRange[0] >= 0 && $absRange[1] >= $absRange[0] ) {
 241                                 if ( $absRange[0] < $size ) {
 242                                         $absRange[1] = min( $absRange[1], $size - 1 ); // stop at EOF
 243                                         $absRange[2] = $absRange[1] - $absRange[0] + 1;
 244                                         return $absRange;
 245                                 } elseif ( $absRange[0] == 0 && $size == 0 ) {
 246                                         return 'unrecognized'; // the whole file should just be sent
 247                                 }
 248                         }
 249                         return 'invalid';
 250                 }
 251                 return 'unrecognized';
 252         }
 253
 254         protected static function resetOutputBuffers() {
 255                 while ( ob_get_status() ) {
 256                         if ( !ob_end_clean() ) {
 257                                 // Could not remove output buffer handler; abort now
 258                                 // to avoid getting in some kind of infinite loop.
 259                                 break;
 260                         }
 261                 }
 262         }
 263
 264         /**
 265          * Determine the file type of a file based on the path
 266          *
 267          * @param string $filename Storage path or file system path
 268          * @return null|string
 269          */
 270         protected static function contentTypeFromPath( $filename ) {
 271                 $ext = strrchr( $filename, '.' );
 272                 $ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
 273
 274                 switch ( $ext ) {
 275                         case 'gif':
 276                                 return 'image/gif';
 277                         case 'png':
 278                                 return 'image/png';
 279                         case 'jpg':
 280                                 return 'image/jpeg';
 281                         case 'jpeg':
 282                                 return 'image/jpeg';
 283                 }
 284
 285                 return 'unknown/unknown';
 286         }
 287 }