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
 203                 // FIXME: Keep logic in sync with MWException::msg.
 204                 try {
 205                         $res = wfMessage( $key, $args )->text();
 206                 } catch ( Exception $e ) {
 207                         $res = wfMsgReplaceArgs( $fallback, $args );
 208                         // If an exception happens inside message rendering,
 209                         // {{SITENAME}} sometimes won't be replaced.
 210                         $res = strtr( $res, [
 211                                 '{{SITENAME}}' => $wgSitename,
 212                         ] );
 213                 }
 214                 return $res;
 215         }
 216
 217         /**
 218          * @param Exception|Throwable $e
 219          * @return string
 220          */
 221         private static function getText( $e ) {
 222                 global $wgShowExceptionDetails;
 223
 224                 if ( $wgShowExceptionDetails ) {
 225                         return MWExceptionHandler::getLogMessage( $e ) .
 226                                 "\nBacktrace:\n" .
 227                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 228                 } else {
 229                         return self::getShowBacktraceError( $e ) . "\n";
 230                 }
 231         }
 232
 233         /**
 234          * @param Exception|Throwable $e
 235          * @return string
 236          */
 237         private static function getShowBacktraceError( $e ) {
 238                 $var = '$wgShowExceptionDetails = true;';
 239                 return "Set $var at the bottom of LocalSettings.php to show detailed debugging information.";
 240         }
 241
 242         /**
 243          * @return bool
 244          */
 245         private static function isCommandLine() {
 246                 return !empty( $GLOBALS['wgCommandLineMode'] );
 247         }
 248
 249         /**
 250          * @param string $header
 251          */
 252         private static function header( $header ) {
 253                 if ( !headers_sent() ) {
 254                         header( $header );
 255                 }
 256         }
 257
 258         /**
 259          * @param int $code
 260          */
 261         private static function statusHeader( $code ) {
 262                 if ( !headers_sent() ) {
 263                         HttpStatus::header( $code );
 264                 }
 265         }
 266
 267         /**
 268          * Print a message, if possible to STDERR.
 269          * Use this in command line mode only (see isCommandLine)
 270          *
 271          * @param string $message Failure text
 272          */
 273         private static function printError( $message ) {
 274                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 275                 // command line (T17602). Try to produce meaningful output anyway. Using
 276                 // echo may corrupt output to STDOUT though.
 277                 if ( defined( 'STDERR' ) ) {
 278                         fwrite( STDERR, $message );
 279                 } else {
 280                         echo $message;
 281                 }
 282         }
 283
 284         /**
 285          * @param Exception|Throwable $e
 286          */
 287         private static function reportOutageHTML( $e ) {
 288                 global $wgShowExceptionDetails, $wgShowHostnames, $wgSitename;
 289
 290                 $sorry = htmlspecialchars( self::msg(
 291                         'dberr-problems',
 292                         'Sorry! This site is experiencing technical difficulties.'
 293                 ) );
 294                 $again = htmlspecialchars( self::msg(
 295                         'dberr-again',
 296                         'Try waiting a few minutes and reloading.'
 297                 ) );
 298
 299                 if ( $wgShowHostnames ) {
 300                         $info = str_replace(
 301                                 '$1',
 302                                 Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
 303                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 304                         );
 305                 } else {
 306                         $info = htmlspecialchars( self::msg(
 307                                 'dberr-info-hidden',
 308                                 '(Cannot access the database)'
 309                         ) );
 310                 }
 311
 312                 MessageCache::singleton()->disable(); // no DB access
 313                 $html = "<!DOCTYPE html>\n" .
 314                                 '<html><head>' .
 315                                 '<title>' .
 316                                 htmlspecialchars( $wgSitename ) .
 317                                 '</title>' .
 318                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 319                                 "</head><body><h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 320
 321                 if ( $wgShowExceptionDetails ) {
 322                         $html .= '<p>Backtrace:</p><pre>' .
 323                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 324                 }
 325
 326                 $html .= '<hr />';
 327                 $html .= self::googleSearchForm();
 328                 $html .= '</body></html>';
 329                 echo $html;
 330         }
 331
 332         /**
 333          * @return string
 334          */
 335         private static function googleSearchForm() {
 336                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 337
 338                 $usegoogle = htmlspecialchars( self::msg(
 339                         'dberr-usegoogle',
 340                         'You can try searching via Google in the meantime.'
 341                 ) );
 342                 $outofdate = htmlspecialchars( self::msg(
 343                         'dberr-outofdate',
 344                         'Note that their indexes of our content may be out of date.'
 345                 ) );
 346                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 347                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 348                 $server = htmlspecialchars( $wgCanonicalServer );
 349                 $sitename = htmlspecialchars( $wgSitename );
 350                 $trygoogle = <<<EOT
 351 <div style="margin: 1.5em">$usegoogle<br />
 352 <small>$outofdate</small>
 353 </div>
 354 <form method="get" action="//www.google.com/search" id="googlesearch">
 355         <input type="hidden" name="domains" value="$server" />
 356         <input type="hidden" name="num" value="50" />
 357         <input type="hidden" name="ie" value="UTF-8" />
 358         <input type="hidden" name="oe" value="UTF-8" />
 359         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 360         <input type="submit" name="btnG" value="$googlesearch" />
 361         <p>
 362                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 363                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 364         </p>
 365 </form>
 366 EOT;
 367                 return $trygoogle;
 368         }
 369 }