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\DBReadOnlyError;
  23 use Wikimedia\Rdbms\DBExpectedError;
  24
  25 /**
  26  * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
  27  * @since 1.28
  28  */
  29 class MWExceptionRenderer {
  30         const AS_RAW = 1; // show as text
  31         const AS_PRETTY = 2; // show as HTML
  32
  33         /**
  34          * @param Exception|Throwable $e Original exception
  35          * @param int $mode MWExceptionExposer::AS_* constant
  36          * @param Exception|Throwable|null $eNew New exception from attempting to show the first
  37          */
  38         public static function output( $e, $mode, $eNew = null ) {
  39                 global $wgMimeType, $wgShowExceptionDetails;
  40
  41                 if ( defined( 'MW_API' ) ) {
  42                         // Unhandled API exception, we can't be sure that format printer is alive
  43                         self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
  44                         wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
  45                 } elseif ( self::isCommandLine() ) {
  46                         self::printError( self::getText( $e ) );
  47                 } elseif ( $mode === self::AS_PRETTY ) {
  48                         self::statusHeader( 500 );
  49                         self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  50                         if ( $e instanceof DBConnectionError ) {
  51                                 self::reportOutageHTML( $e );
  52                         } else {
  53                                 self::reportHTML( $e );
  54                         }
  55                 } else {
  56                         self::statusHeader( 500 );
  57                         self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  58                         if ( $eNew ) {
  59                                 $message = "MediaWiki internal error.\n\n";
  60                                 if ( $wgShowExceptionDetails ) {
  61                                         $message .= 'Original exception: ' .
  62                                                 MWExceptionHandler::getLogMessage( $e ) .
  63                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
  64                                                 "\n\nException caught inside exception handler: " .
  65                                                         MWExceptionHandler::getLogMessage( $eNew ) .
  66                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
  67                                 } else {
  68                                         $message .= 'Original exception: ' .
  69                                                 MWExceptionHandler::getPublicLogMessage( $e );
  70                                         $message .= "\n\nException caught inside exception handler.\n\n" .
  71                                                 self::getShowBacktraceError( $e );
  72                                 }
  73                                 $message .= "\n";
  74                         } elseif ( $wgShowExceptionDetails ) {
  75                                 $message = MWExceptionHandler::getLogMessage( $e ) .
  76                                         "\nBacktrace:\n" .
  77                                         MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  78                         } else {
  79                                 $message = MWExceptionHandler::getPublicLogMessage( $e );
  80                         }
  81                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
  82                 }
  83         }
  84
  85         /**
  86          * @param Exception|Throwable $e
  87          * @return bool Should the exception use $wgOut to output the error?
  88          */
  89         private static function useOutputPage( $e ) {
  90                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
  91                 foreach ( $e->getTrace() as $frame ) {
  92                         if ( isset( $frame['class'] ) && $frame['class'] === LocalisationCache::class ) {
  93                                 return false;
  94                         }
  95                 }
  96
  97                 // Don't even bother with OutputPage if there's no Title context set,
  98                 // (e.g. we're in RL code on load.php) - the Skin system (and probably
  99                 // most of MediaWiki) won't work.
 100
 101                 return (
 102                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 103                         !empty( $GLOBALS['wgOut'] ) &&
 104                         RequestContext::getMain()->getTitle() &&
 105                         !defined( 'MEDIAWIKI_INSTALL' )
 106                 );
 107         }
 108
 109         /**
 110          * Output the exception report using HTML
 111          *
 112          * @param Exception|Throwable $e
 113          */
 114         private static function reportHTML( $e ) {
 115                 global $wgOut, $wgSitename;
 116
 117                 if ( self::useOutputPage( $e ) ) {
 118                         if ( $e instanceof MWException ) {
 119                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 120                         } elseif ( $e instanceof DBReadOnlyError ) {
 121                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 122                         } elseif ( $e instanceof DBExpectedError ) {
 123                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 124                         } else {
 125                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 126                         }
 127
 128                         // Show any custom GUI message before the details
 129                         if ( $e instanceof MessageSpecifier ) {
 130                                 $wgOut->addHTML( Html::element( 'p', [], Message::newFromSpecifier( $e )->text() ) );
 131                         }
 132                         $wgOut->addHTML( self::getHTML( $e ) );
 133
 134                         $wgOut->output();
 135                 } else {
 136                         self::header( 'Content-Type: text/html; charset=utf-8' );
 137                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 138                         echo "<!DOCTYPE html>\n" .
 139                                 '<html><head>' .
 140                                 // Mimick OutputPage::setPageTitle behaviour
 141                                 '<title>' .
 142                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 143                                 '</title>' .
 144                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 145                                 "</head><body>\n";
 146
 147                         echo self::getHTML( $e );
 148
 149                         echo "</body></html>\n";
 150                 }
 151         }
 152
 153         /**
 154          * If $wgShowExceptionDetails is true, return a HTML message with a
 155          * backtrace to the error, otherwise show a message to ask to set it to true
 156          * to show that information.
 157          *
 158          * @param Exception|Throwable $e
 159          * @return string Html to output
 160          */
 161         public static function getHTML( $e ) {
 162                 global $wgShowExceptionDetails;
 163
 164                 if ( $wgShowExceptionDetails ) {
 165                         $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
 166                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 167                                 '</p><p>Backtrace:</p><p>' .
 168                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 169                                 "</p></div>\n";
 170                 } else {
 171                         $logId = WebRequest::getRequestId();
 172                         $html = "<div class=\"errorbox mw-content-ltr\">" .
 173                                 htmlspecialchars(
 174                                         '[' . $logId . '] ' .
 175                                         gmdate( 'Y-m-d H:i:s' ) . ": " .
 176                                         self::msg( "internalerror-fatal-exception",
 177                                                 "Fatal exception of type $1",
 178                                                 get_class( $e ),
 179                                                 $logId,
 180                                                 MWExceptionHandler::getURL()
 181                                 ) ) . "</div>\n" .
 182                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 183                 }
 184
 185                 return $html;
 186         }
 187
 188         /**
 189          * Get a message from i18n
 190          *
 191          * @param string $key Message name
 192          * @param string $fallback Default message if the message cache can't be
 193          *                  called by the exception
 194          * The function also has other parameters that are arguments for the message
 195          * @return string Message with arguments replaced
 196          */
 197         private static function msg( $key, $fallback /*[, params...] */ ) {
 198                 global $wgSitename;
 199                 $args = array_slice( func_get_args(), 2 );
 200
 201                 // FIXME: Keep logic in sync with MWException::msg.
 202                 try {
 203                         $res = wfMessage( $key, $args )->text();
 204                 } catch ( Exception $e ) {
 205                         $res = wfMsgReplaceArgs( $fallback, $args );
 206                         // If an exception happens inside message rendering,
 207                         // {{SITENAME}} sometimes won't be replaced.
 208                         $res = strtr( $res, [
 209                                 '{{SITENAME}}' => $wgSitename,
 210                         ] );
 211                 }
 212                 return $res;
 213         }
 214
 215         /**
 216          * @param Exception|Throwable $e
 217          * @return string
 218          */
 219         private static function getText( $e ) {
 220                 global $wgShowExceptionDetails;
 221
 222                 if ( $wgShowExceptionDetails ) {
 223                         return MWExceptionHandler::getLogMessage( $e ) .
 224                                 "\nBacktrace:\n" .
 225                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 226                 } else {
 227                         return self::getShowBacktraceError( $e ) . "\n";
 228                 }
 229         }
 230
 231         /**
 232          * @param Exception|Throwable $e
 233          * @return string
 234          */
 235         private static function getShowBacktraceError( $e ) {
 236                 $var = '$wgShowExceptionDetails = true;';
 237                 return "Set $var at the bottom of LocalSettings.php to show detailed debugging information.";
 238         }
 239
 240         /**
 241          * @return bool
 242          */
 243         private static function isCommandLine() {
 244                 return !empty( $GLOBALS['wgCommandLineMode'] );
 245         }
 246
 247         /**
 248          * @param string $header
 249          */
 250         private static function header( $header ) {
 251                 if ( !headers_sent() ) {
 252                         header( $header );
 253                 }
 254         }
 255
 256         /**
 257          * @param int $code
 258          */
 259         private static function statusHeader( $code ) {
 260                 if ( !headers_sent() ) {
 261                         HttpStatus::header( $code );
 262                 }
 263         }
 264
 265         /**
 266          * Print a message, if possible to STDERR.
 267          * Use this in command line mode only (see isCommandLine)
 268          *
 269          * @suppress SecurityCheck-XSS
 270          * @param string $message Failure text
 271          */
 272         private static function printError( $message ) {
 273                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 274                 // command line (T17602). Try to produce meaningful output anyway. Using
 275                 // echo may corrupt output to STDOUT though.
 276                 if ( defined( 'STDERR' ) ) {
 277                         fwrite( STDERR, $message );
 278                 } else {
 279                         echo $message;
 280                 }
 281         }
 282
 283         /**
 284          * @param Exception|Throwable $e
 285          */
 286         private static function reportOutageHTML( $e ) {
 287                 global $wgShowExceptionDetails, $wgShowHostnames, $wgSitename;
 288
 289                 $sorry = htmlspecialchars( self::msg(
 290                         'dberr-problems',
 291                         'Sorry! This site is experiencing technical difficulties.'
 292                 ) );
 293                 $again = htmlspecialchars( self::msg(
 294                         'dberr-again',
 295                         'Try waiting a few minutes and reloading.'
 296                 ) );
 297
 298                 if ( $wgShowHostnames ) {
 299                         $info = str_replace(
 300                                 '$1',
 301                                 Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
 302                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 303                         );
 304                 } else {
 305                         $info = htmlspecialchars( self::msg(
 306                                 'dberr-info-hidden',
 307                                 '(Cannot access the database)'
 308                         ) );
 309                 }
 310
 311                 MessageCache::singleton()->disable(); // no DB access
 312                 $html = "<!DOCTYPE html>\n" .
 313                                 '<html><head>' .
 314                                 '<title>' .
 315                                 htmlspecialchars( $wgSitename ) .
 316                                 '</title>' .
 317                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 318                                 "</head><body><h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 319
 320                 if ( $wgShowExceptionDetails ) {
 321                         $html .= '<p>Backtrace:</p><pre>' .
 322                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 323                 }
 324
 325                 $html .= '</body></html>';
 326                 echo $html;
 327         }
 328 }