includes/exception/MWExceptionRenderer.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  */
  20
  21 use Wikimedia\Rdbms\DBConnectionError;
  22 use Wikimedia\Rdbms\DBError;
  23 use Wikimedia\Rdbms\DBReadOnlyError;
  24 use Wikimedia\Rdbms\DBExpectedError;
  25
  26 /**
  27  * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
  28  * @since 1.28
  29  */
  30 class MWExceptionRenderer {
  31         const AS_RAW = 1; // show as text
  32         const AS_PRETTY = 2; // show as HTML
  33
  34         /**
  35          * @param Exception|Throwable $e Original exception
  36          * @param int $mode MWExceptionExposer::AS_* constant
  37          * @param Exception|Throwable|null $eNew New exception from attempting to show the first
  38          */
  39         public static function output( $e, $mode, $eNew = null ) {
  40                 global $wgMimeType;
  41
  42                 if ( defined( 'MW_API' ) ) {
  43                         // Unhandled API exception, we can't be sure that format printer is alive
  44                         self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
  45                         wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
  46                 } elseif ( self::isCommandLine() ) {
  47                         self::printError( self::getText( $e ) );
  48                 } elseif ( $mode === self::AS_PRETTY ) {
  49                         self::statusHeader( 500 );
  50                         self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  51                         if ( $e instanceof DBConnectionError ) {
  52                                 self::reportOutageHTML( $e );
  53                         } else {
  54                                 self::reportHTML( $e );
  55                         }
  56                 } else {
  57                         self::statusHeader( 500 );
  58                         self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  59                         if ( $eNew ) {
  60                                 $message = "MediaWiki internal error.\n\n";
  61                                 if ( self::showBackTrace( $e ) ) {
  62                                         $message .= 'Original exception: ' .
  63                                                 MWExceptionHandler::getLogMessage( $e ) .
  64                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
  65                                                 "\n\nException caught inside exception handler: " .
  66                                                         MWExceptionHandler::getLogMessage( $eNew ) .
  67                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
  68                                 } else {
  69                                         $message .= 'Original exception: ' .
  70                                                 MWExceptionHandler::getPublicLogMessage( $e );
  71                                         $message .= "\n\nException caught inside exception handler.\n\n" .
  72                                                 self::getShowBacktraceError( $e );
  73                                 }
  74                                 $message .= "\n";
  75                         } else {
  76                                 if ( self::showBackTrace( $e ) ) {
  77                                         $message = MWExceptionHandler::getLogMessage( $e ) .
  78                                                 "\nBacktrace:\n" .
  79                                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  80                                 } else {
  81                                         $message = MWExceptionHandler::getPublicLogMessage( $e );
  82                                 }
  83                         }
  84                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
  85                 }
  86         }
  87
  88         /**
  89          * @param Exception|Throwable $e
  90          * @return bool Should the exception use $wgOut to output the error?
  91          */
  92         private static function useOutputPage( $e ) {
  93                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
  94                 foreach ( $e->getTrace() as $frame ) {
  95                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
  96                                 return false;
  97                         }
  98                 }
  99
 100                 // Don't even bother with OutputPage if there's no Title context set,
 101                 // (e.g. we're in RL code on load.php) - the Skin system (and probably
 102                 // most of MediaWiki) won't work.
 103
 104                 return (
 105                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 106                         !empty( $GLOBALS['wgOut'] ) &&
 107                         RequestContext::getMain()->getTitle() &&
 108                         !defined( 'MEDIAWIKI_INSTALL' )
 109                 );
 110         }
 111
 112         /**
 113          * Output the exception report using HTML
 114          *
 115          * @param Exception|Throwable $e
 116          */
 117         private static function reportHTML( $e ) {
 118                 global $wgOut, $wgSitename;
 119
 120                 if ( self::useOutputPage( $e ) ) {
 121                         if ( $e instanceof MWException ) {
 122                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 123                         } elseif ( $e instanceof DBReadOnlyError ) {
 124                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 125                         } elseif ( $e instanceof DBExpectedError ) {
 126                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 127                         } else {
 128                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 129                         }
 130
 131                         // Show any custom GUI message before the details
 132                         if ( $e instanceof MessageSpecifier ) {
 133                                 $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 134                         }
 135                         $wgOut->addHTML( self::getHTML( $e ) );
 136
 137                         $wgOut->output();
 138                 } else {
 139                         self::header( 'Content-Type: text/html; charset=utf-8' );
 140                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 141                         echo "<!DOCTYPE html>\n" .
 142                                 '<html><head>' .
 143                                 // Mimick OutputPage::setPageTitle behaviour
 144                                 '<title>' .
 145                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 146                                 '</title>' .
 147                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 148                                 "</head><body>\n";
 149
 150                         echo self::getHTML( $e );
 151
 152                         echo "</body></html>\n";
 153                 }
 154         }
 155
 156         /**
 157          * If $wgShowExceptionDetails is true, return a HTML message with a
 158          * backtrace to the error, otherwise show a message to ask to set it to true
 159          * to show that information.
 160          *
 161          * @param Exception|Throwable $e
 162          * @return string Html to output
 163          */
 164         public static function getHTML( $e ) {
 165                 if ( self::showBackTrace( $e ) ) {
 166                         $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
 167                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 168                                 '</p><p>Backtrace:</p><p>' .
 169                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 170                                 "</p></div>\n";
 171                 } else {
 172                         $logId = WebRequest::getRequestId();
 173                         $html = "<div class=\"errorbox mw-content-ltr\">" .
 174                                 htmlspecialchars(
 175                                         '[' . $logId . '] ' .
 176                                         gmdate( 'Y-m-d H:i:s' ) . ": " .
 177                                         self::msg( "internalerror-fatal-exception",
 178                                                 "Fatal exception of type $1",
 179                                                 get_class( $e ),
 180                                                 $logId,
 181                                                 MWExceptionHandler::getURL()
 182                                         )
 183                                 ) . "</div>\n" .
 184                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 185                 }
 186
 187                 return $html;
 188         }
 189
 190         /**
 191          * Get a message from i18n
 192          *
 193          * @param string $key Message name
 194          * @param string $fallback Default message if the message cache can't be
 195          *                  called by the exception
 196          * The function also has other parameters that are arguments for the message
 197          * @return string Message with arguments replaced
 198          */
 199         private static function msg( $key, $fallback /*[, params...] */ ) {
 200                 $args = array_slice( func_get_args(), 2 );
 201                 try {
 202                         return wfMessage( $key, $args )->text();
 203                 } catch ( Exception $e ) {
 204                         return wfMsgReplaceArgs( $fallback, $args );
 205                 }
 206         }
 207
 208         /**
 209          * @param Exception|Throwable $e
 210          * @return string
 211          */
 212         private static function getText( $e ) {
 213                 if ( self::showBackTrace( $e ) ) {
 214                         return MWExceptionHandler::getLogMessage( $e ) .
 215                                 "\nBacktrace:\n" .
 216                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 217                 } else {
 218                         return self::getShowBacktraceError( $e ) . "\n";
 219                 }
 220         }
 221
 222         /**
 223          * @param Exception|Throwable $e
 224          * @return bool
 225          */
 226         private static function showBackTrace( $e ) {
 227                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 228
 229                 return (
 230                         $wgShowExceptionDetails &&
 231                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 232                 );
 233         }
 234
 235         /**
 236          * @param Exception|Throwable $e
 237          * @return string
 238          */
 239         private static function getShowBacktraceError( $e ) {
 240                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 241                 $vars = [];
 242                 if ( !$wgShowExceptionDetails ) {
 243                         $vars[] = '$wgShowExceptionDetails = true;';
 244                 }
 245                 if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
 246                         $vars[] = '$wgShowDBErrorBacktrace = true;';
 247                 }
 248                 $vars = implode( ' and ', $vars );
 249                 return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information.";
 250         }
 251
 252         /**
 253          * @return bool
 254          */
 255         private static function isCommandLine() {
 256                 return !empty( $GLOBALS['wgCommandLineMode'] );
 257         }
 258
 259         /**
 260          * @param string $header
 261          */
 262         private static function header( $header ) {
 263                 if ( !headers_sent() ) {
 264                         header( $header );
 265                 }
 266         }
 267
 268         /**
 269          * @param int $code
 270          */
 271         private static function statusHeader( $code ) {
 272                 if ( !headers_sent() ) {
 273                         HttpStatus::header( $code );
 274                 }
 275         }
 276
 277         /**
 278          * Print a message, if possible to STDERR.
 279          * Use this in command line mode only (see isCommandLine)
 280          *
 281          * @param string $message Failure text
 282          */
 283         private static function printError( $message ) {
 284                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 285                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 286                 // echo may corrupt output to STDOUT though.
 287                 if ( defined( 'STDERR' ) ) {
 288                         fwrite( STDERR, $message );
 289                 } else {
 290                         echo $message;
 291                 }
 292         }
 293
 294         /**
 295          * @param Exception|Throwable $e
 296          */
 297         private static function reportOutageHTML( $e ) {
 298                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors, $wgSitename;
 299
 300                 $sorry = htmlspecialchars( self::msg(
 301                         'dberr-problems',
 302                         'Sorry! This site is experiencing technical difficulties.'
 303                 ) );
 304                 $again = htmlspecialchars( self::msg(
 305                         'dberr-again',
 306                         'Try waiting a few minutes and reloading.'
 307                 ) );
 308
 309                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 310                         $info = str_replace(
 311                                 '$1',
 312                                 Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
 313                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 314                         );
 315                 } else {
 316                         $info = htmlspecialchars( self::msg(
 317                                 'dberr-info-hidden',
 318                                 '(Cannot access the database)'
 319                         ) );
 320                 }
 321
 322                 MessageCache::singleton()->disable(); // no DB access
 323                 $html = "<!DOCTYPE html>\n" .
 324                                 '<html><head>' .
 325                                 '<title>' .
 326                                 htmlspecialchars( $wgSitename ) .
 327                                 '</title>' .
 328                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 329                                 "</head><body><h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 330
 331                 if ( $wgShowDBErrorBacktrace ) {
 332                         $html .= '<p>Backtrace:</p><pre>' .
 333                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 334                 }
 335
 336                 $html .= '</body></html>';
 337                 echo $html;
 338         }
 339 }