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 integer $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                         if ( $e instanceof DBConnectionError ) {
  51                                 self::reportOutageHTML( $e );
  52                         } else {
  53                                 self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  54                                 self::reportHTML( $e );
  55                         }
  56                 } else {
  57                         if ( $eNew ) {
  58                                 $message = "MediaWiki internal error.\n\n";
  59                                 if ( self::showBackTrace( $e ) ) {
  60                                         $message .= 'Original exception: ' .
  61                                                 MWExceptionHandler::getLogMessage( $e ) .
  62                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
  63                                                 "\n\nException caught inside exception handler: " .
  64                                                         MWExceptionHandler::getLogMessage( $eNew ) .
  65                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
  66                                 } else {
  67                                         $message .= 'Original exception: ' .
  68                                                 MWExceptionHandler::getPublicLogMessage( $e );
  69                                         $message .= "\n\nException caught inside exception handler.\n\n" .
  70                                                 self::getShowBacktraceError( $e );
  71                                 }
  72                                 $message .= "\n";
  73                         } else {
  74                                 if ( self::showBackTrace( $e ) ) {
  75                                         $message = MWExceptionHandler::getLogMessage( $e ) .
  76                                                 "\nBacktrace:\n" .
  77                                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  78                                 } else {
  79                                         $message = MWExceptionHandler::getPublicLogMessage( $e );
  80                                 }
  81                         }
  82                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
  83                 }
  84         }
  85
  86         /**
  87          * @param Exception|Throwable $e
  88          * @return bool Should the exception use $wgOut to output the error?
  89          */
  90         private static function useOutputPage( $e ) {
  91                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
  92                 foreach ( $e->getTrace() as $frame ) {
  93                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
  94                                 return false;
  95                         }
  96                 }
  97
  98                 // Don't even bother with OutputPage if there's no Title context set,
  99                 // (e.g. we're in RL code on load.php) - the Skin system (and probably
 100                 // most of MediaWiki) won't work.
 101
 102                 return (
 103                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 104                         !empty( $GLOBALS['wgOut'] ) &&
 105                         RequestContext::getMain()->getTitle() &&
 106                         !defined( 'MEDIAWIKI_INSTALL' )
 107                 );
 108         }
 109
 110         /**
 111          * Output the exception report using HTML
 112          *
 113          * @param Exception|Throwable $e
 114          */
 115         private static function reportHTML( $e ) {
 116                 global $wgOut, $wgSitename;
 117
 118                 if ( self::useOutputPage( $e ) ) {
 119                         if ( $e instanceof MWException ) {
 120                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 121                         } elseif ( $e instanceof DBReadOnlyError ) {
 122                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 123                         } elseif ( $e instanceof DBExpectedError ) {
 124                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 125                         } else {
 126                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 127                         }
 128
 129                         // Show any custom GUI message before the details
 130                         if ( $e instanceof MessageSpecifier ) {
 131                                 $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 132                         }
 133                         $wgOut->addHTML( self::getHTML( $e ) );
 134
 135                         $wgOut->output();
 136                 } else {
 137                         self::header( 'Content-Type: text/html; charset=utf-8' );
 138                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 139                         echo "<!DOCTYPE html>\n" .
 140                                 '<html><head>' .
 141                                 // Mimick OutputPage::setPageTitle behaviour
 142                                 '<title>' .
 143                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 144                                 '</title>' .
 145                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 146                                 "</head><body>\n";
 147
 148                         echo self::getHTML( $e );
 149
 150                         echo "</body></html>\n";
 151                 }
 152         }
 153
 154         /**
 155          * If $wgShowExceptionDetails is true, return a HTML message with a
 156          * backtrace to the error, otherwise show a message to ask to set it to true
 157          * to show that information.
 158          *
 159          * @param Exception|Throwable $e
 160          * @return string Html to output
 161          */
 162         public static function getHTML( $e ) {
 163                 if ( self::showBackTrace( $e ) ) {
 164                         $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
 165                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 166                                 '</p><p>Backtrace:</p><p>' .
 167                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 168                                 "</p></div>\n";
 169                 } else {
 170                         $logId = WebRequest::getRequestId();
 171                         $html = "<div class=\"errorbox mw-content-ltr\">" .
 172                                 '[' . $logId . '] ' .
 173                                 gmdate( 'Y-m-d H:i:s' ) . ": " .
 174                                 self::msg( "internalerror-fatal-exception",
 175                                         "Fatal exception of type $1",
 176                                         get_class( $e ),
 177                                         $logId,
 178                                         MWExceptionHandler::getURL()
 179                                 ) . "</div>\n" .
 180                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 181                 }
 182
 183                 return $html;
 184         }
 185
 186         /**
 187          * Get a message from i18n
 188          *
 189          * @param string $key Message name
 190          * @param string $fallback Default message if the message cache can't be
 191          *                  called by the exception
 192          * The function also has other parameters that are arguments for the message
 193          * @return string Message with arguments replaced
 194          */
 195         private static function msg( $key, $fallback /*[, params...] */ ) {
 196                 $args = array_slice( func_get_args(), 2 );
 197                 try {
 198                         return wfMessage( $key, $args )->text();
 199                 } catch ( Exception $e ) {
 200                         return wfMsgReplaceArgs( $fallback, $args );
 201                 }
 202         }
 203
 204         /**
 205          * @param Exception|Throwable $e
 206          * @return string
 207          */
 208         private static function getText( $e ) {
 209                 if ( self::showBackTrace( $e ) ) {
 210                         return MWExceptionHandler::getLogMessage( $e ) .
 211                                 "\nBacktrace:\n" .
 212                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 213                 } else {
 214                         return self::getShowBacktraceError( $e ) . "\n";
 215                 }
 216         }
 217
 218         /**
 219          * @param Exception|Throwable $e
 220          * @return bool
 221          */
 222         private static function showBackTrace( $e ) {
 223                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 224
 225                 return (
 226                         $wgShowExceptionDetails &&
 227                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 228                 );
 229         }
 230
 231         /**
 232          * @param Exception|Throwable $e
 233          * @return string
 234          */
 235         private static function getShowBacktraceError( $e ) {
 236                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 237                 $vars = [];
 238                 if ( !$wgShowExceptionDetails ) {
 239                         $vars[] = '$wgShowExceptionDetails = true;';
 240                 }
 241                 if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
 242                         $vars[] = '$wgShowDBErrorBacktrace = true;';
 243                 }
 244                 $vars = implode( ' and ', $vars );
 245                 return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information.";
 246         }
 247
 248         /**
 249          * @return bool
 250          */
 251         private static function isCommandLine() {
 252                 return !empty( $GLOBALS['wgCommandLineMode'] );
 253         }
 254
 255         /**
 256          * @param string $header
 257          */
 258         private static function header( $header ) {
 259                 if ( !headers_sent() ) {
 260                         header( $header );
 261                 }
 262         }
 263
 264         /**
 265          * @param integer $code
 266          */
 267         private static function statusHeader( $code ) {
 268                 if ( !headers_sent() ) {
 269                         HttpStatus::header( $code );
 270                 }
 271         }
 272
 273         /**
 274          * Print a message, if possible to STDERR.
 275          * Use this in command line mode only (see isCommandLine)
 276          *
 277          * @param string $message Failure text
 278          */
 279         private static function printError( $message ) {
 280                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 281                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 282                 // echo may corrupt output to STDOUT though.
 283                 if ( defined( 'STDERR' ) ) {
 284                         fwrite( STDERR, $message );
 285                 } else {
 286                         echo $message;
 287                 }
 288         }
 289
 290         /**
 291          * @param Exception|Throwable $e
 292          */
 293         private static function reportOutageHTML( $e ) {
 294                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 295
 296                 $sorry = htmlspecialchars( self::msg(
 297                         'dberr-problems',
 298                         'Sorry! This site is experiencing technical difficulties.'
 299                 ) );
 300                 $again = htmlspecialchars( self::msg(
 301                         'dberr-again',
 302                         'Try waiting a few minutes and reloading.'
 303                 ) );
 304
 305                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 306                         $info = str_replace(
 307                                 '$1',
 308                                 Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
 309                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 310                         );
 311                 } else {
 312                         $info = htmlspecialchars( self::msg(
 313                                 'dberr-info-hidden',
 314                                 '(Cannot access the database)'
 315                         ) );
 316                 }
 317
 318                 MessageCache::singleton()->disable(); // no DB access
 319
 320                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 321
 322                 if ( $wgShowDBErrorBacktrace ) {
 323                         $html .= '<p>Backtrace:</p><pre>' .
 324                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 325                 }
 326
 327                 $html .= '<hr />';
 328                 $html .= self::googleSearchForm();
 329
 330                 echo $html;
 331         }
 332
 333         /**
 334          * @return string
 335          */
 336         private static function googleSearchForm() {
 337                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 338
 339                 $usegoogle = htmlspecialchars( self::msg(
 340                         'dberr-usegoogle',
 341                         'You can try searching via Google in the meantime.'
 342                 ) );
 343                 $outofdate = htmlspecialchars( self::msg(
 344                         'dberr-outofdate',
 345                         'Note that their indexes of our content may be out of date.'
 346                 ) );
 347                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 348                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 349                 $server = htmlspecialchars( $wgCanonicalServer );
 350                 $sitename = htmlspecialchars( $wgSitename );
 351                 $trygoogle = <<<EOT
 352 <div style="margin: 1.5em">$usegoogle<br />
 353 <small>$outofdate</small>
 354 </div>
 355 <form method="get" action="//www.google.com/search" id="googlesearch">
 356         <input type="hidden" name="domains" value="$server" />
 357         <input type="hidden" name="num" value="50" />
 358         <input type="hidden" name="ie" value="UTF-8" />
 359         <input type="hidden" name="oe" value="UTF-8" />
 360         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 361         <input type="submit" name="btnG" value="$googlesearch" />
 362         <p>
 363                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 364                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 365         </p>
 366 </form>
 367 EOT;
 368                 return $trygoogle;
 369         }
 370 }