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                         } else {
  75                                 if ( $wgShowExceptionDetails ) {
  76                                         $message = MWExceptionHandler::getLogMessage( $e ) .
  77                                                 "\nBacktrace:\n" .
  78                                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  79                                 } else {
  80                                         $message = MWExceptionHandler::getPublicLogMessage( $e );
  81                                 }
  82                         }
  83                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
  84                 }
  85         }
  86
  87         /**
  88          * @param Exception|Throwable $e
  89          * @return bool Should the exception use $wgOut to output the error?
  90          */
  91         private static function useOutputPage( $e ) {
  92                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
  93                 foreach ( $e->getTrace() as $frame ) {
  94                         if ( isset( $frame['class'] ) && $frame['class'] === LocalisationCache::class ) {
  95                                 return false;
  96                         }
  97                 }
  98
  99                 // Don't even bother with OutputPage if there's no Title context set,
 100                 // (e.g. we're in RL code on load.php) - the Skin system (and probably
 101                 // most of MediaWiki) won't work.
 102
 103                 return (
 104                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 105                         !empty( $GLOBALS['wgOut'] ) &&
 106                         RequestContext::getMain()->getTitle() &&
 107                         !defined( 'MEDIAWIKI_INSTALL' )
 108                 );
 109         }
 110
 111         /**
 112          * Output the exception report using HTML
 113          *
 114          * @param Exception|Throwable $e
 115          */
 116         private static function reportHTML( $e ) {
 117                 global $wgOut, $wgSitename;
 118
 119                 if ( self::useOutputPage( $e ) ) {
 120                         if ( $e instanceof MWException ) {
 121                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 122                         } elseif ( $e instanceof DBReadOnlyError ) {
 123                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 124                         } elseif ( $e instanceof DBExpectedError ) {
 125                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 126                         } else {
 127                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 128                         }
 129
 130                         // Show any custom GUI message before the details
 131                         if ( $e instanceof MessageSpecifier ) {
 132                                 $wgOut->addHTML( Html::element( 'p', [], Message::newFromSpecifier( $e )->text() ) );
 133                         }
 134                         $wgOut->addHTML( self::getHTML( $e ) );
 135
 136                         $wgOut->output();
 137                 } else {
 138                         self::header( 'Content-Type: text/html; charset=utf-8' );
 139                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 140                         echo "<!DOCTYPE html>\n" .
 141                                 '<html><head>' .
 142                                 // Mimick OutputPage::setPageTitle behaviour
 143                                 '<title>' .
 144                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 145                                 '</title>' .
 146                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 147                                 "</head><body>\n";
 148
 149                         echo self::getHTML( $e );
 150
 151                         echo "</body></html>\n";
 152                 }
 153         }
 154
 155         /**
 156          * If $wgShowExceptionDetails is true, return a HTML message with a
 157          * backtrace to the error, otherwise show a message to ask to set it to true
 158          * to show that information.
 159          *
 160          * @param Exception|Throwable $e
 161          * @return string Html to output
 162          */
 163         public static function getHTML( $e ) {
 164                 global $wgShowExceptionDetails;
 165
 166                 if ( $wgShowExceptionDetails ) {
 167                         $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
 168                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 169                                 '</p><p>Backtrace:</p><p>' .
 170                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 171                                 "</p></div>\n";
 172                 } else {
 173                         $logId = WebRequest::getRequestId();
 174                         $html = "<div class=\"errorbox mw-content-ltr\">" .
 175                                 htmlspecialchars(
 176                                         '[' . $logId . '] ' .
 177                                         gmdate( 'Y-m-d H:i:s' ) . ": " .
 178                                         self::msg( "internalerror-fatal-exception",
 179                                                 "Fatal exception of type $1",
 180                                                 get_class( $e ),
 181                                                 $logId,
 182                                                 MWExceptionHandler::getURL()
 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                 global $wgSitename;
 201                 $args = array_slice( func_get_args(), 2 );
 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 = preg_replace( '/\{\{SITENAME\}\}/', $wgSitename, $res );
 209                 }
 210                 return $res;
 211         }
 212
 213         /**
 214          * @param Exception|Throwable $e
 215          * @return string
 216          */
 217         private static function getText( $e ) {
 218                 global $wgShowExceptionDetails;
 219
 220                 if ( $wgShowExceptionDetails ) {
 221                         return MWExceptionHandler::getLogMessage( $e ) .
 222                                 "\nBacktrace:\n" .
 223                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 224                 } else {
 225                         return self::getShowBacktraceError( $e ) . "\n";
 226                 }
 227         }
 228
 229         /**
 230          * @param Exception|Throwable $e
 231          * @return string
 232          */
 233         private static function getShowBacktraceError( $e ) {
 234                 $var = '$wgShowExceptionDetails = true;';
 235                 return "Set $var at the bottom of LocalSettings.php to show detailed debugging information.";
 236         }
 237
 238         /**
 239          * @return bool
 240          */
 241         private static function isCommandLine() {
 242                 return !empty( $GLOBALS['wgCommandLineMode'] );
 243         }
 244
 245         /**
 246          * @param string $header
 247          */
 248         private static function header( $header ) {
 249                 if ( !headers_sent() ) {
 250                         header( $header );
 251                 }
 252         }
 253
 254         /**
 255          * @param int $code
 256          */
 257         private static function statusHeader( $code ) {
 258                 if ( !headers_sent() ) {
 259                         HttpStatus::header( $code );
 260                 }
 261         }
 262
 263         /**
 264          * Print a message, if possible to STDERR.
 265          * Use this in command line mode only (see isCommandLine)
 266          *
 267          * @param string $message Failure text
 268          */
 269         private static function printError( $message ) {
 270                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 271                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 272                 // echo may corrupt output to STDOUT though.
 273                 if ( defined( 'STDERR' ) ) {
 274                         fwrite( STDERR, $message );
 275                 } else {
 276                         echo $message;
 277                 }
 278         }
 279
 280         /**
 281          * @param Exception|Throwable $e
 282          */
 283         private static function reportOutageHTML( $e ) {
 284                 global $wgShowExceptionDetails, $wgShowHostnames, $wgSitename;
 285
 286                 $sorry = htmlspecialchars( self::msg(
 287                         'dberr-problems',
 288                         'Sorry! This site is experiencing technical difficulties.'
 289                 ) );
 290                 $again = htmlspecialchars( self::msg(
 291                         'dberr-again',
 292                         'Try waiting a few minutes and reloading.'
 293                 ) );
 294
 295                 if ( $wgShowHostnames ) {
 296                         $info = str_replace(
 297                                 '$1',
 298                                 Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
 299                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 300                         );
 301                 } else {
 302                         $info = htmlspecialchars( self::msg(
 303                                 'dberr-info-hidden',
 304                                 '(Cannot access the database)'
 305                         ) );
 306                 }
 307
 308                 MessageCache::singleton()->disable(); // no DB access
 309                 $html = "<!DOCTYPE html>\n" .
 310                                 '<html><head>' .
 311                                 '<title>' .
 312                                 htmlspecialchars( $wgSitename ) .
 313                                 '</title>' .
 314                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 315                                 "</head><body><h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 316
 317                 if ( $wgShowExceptionDetails ) {
 318                         $html .= '<p>Backtrace:</p><pre>' .
 319                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 320                 }
 321
 322                 $html .= '<hr />';
 323                 $html .= self::googleSearchForm();
 324                 $html .= '</body></html>';
 325                 echo $html;
 326         }
 327
 328         /**
 329          * @return string
 330          */
 331         private static function googleSearchForm() {
 332                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 333
 334                 $usegoogle = htmlspecialchars( self::msg(
 335                         'dberr-usegoogle',
 336                         'You can try searching via Google in the meantime.'
 337                 ) );
 338                 $outofdate = htmlspecialchars( self::msg(
 339                         'dberr-outofdate',
 340                         'Note that their indexes of our content may be out of date.'
 341                 ) );
 342                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 343                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 344                 $server = htmlspecialchars( $wgCanonicalServer );
 345                 $sitename = htmlspecialchars( $wgSitename );
 346                 $trygoogle = <<<EOT
 347 <div style="margin: 1.5em">$usegoogle<br />
 348 <small>$outofdate</small>
 349 </div>
 350 <form method="get" action="//www.google.com/search" id="googlesearch">
 351         <input type="hidden" name="domains" value="$server" />
 352         <input type="hidden" name="num" value="50" />
 353         <input type="hidden" name="ie" value="UTF-8" />
 354         <input type="hidden" name="oe" value="UTF-8" />
 355         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 356         <input type="submit" name="btnG" value="$googlesearch" />
 357         <p>
 358                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 359                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 360         </p>
 361 </form>
 362 EOT;
 363                 return $trygoogle;
 364         }
 365 }