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  * @author Aaron Schulz
  20  */
  21
  22 use Wikimedia\Rdbms\DBConnectionError;
  23 use Wikimedia\Rdbms\DBError;
  24 use Wikimedia\Rdbms\DBReadOnlyError;
  25 use Wikimedia\Rdbms\DBExpectedError;
  26
  27 /**
  28  * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
  29  * @since 1.28
  30  */
  31 class MWExceptionRenderer {
  32         const AS_RAW = 1; // show as text
  33         const AS_PRETTY = 2; // show as HTML
  34
  35         /**
  36          * @param Exception|Throwable $e Original exception
  37          * @param integer $mode MWExceptionExposer::AS_* constant
  38          * @param Exception|Throwable|null $eNew New exception from attempting to show the first
  39          */
  40         public static function output( $e, $mode, $eNew = null ) {
  41                 global $wgMimeType;
  42
  43                 if ( defined( 'MW_API' ) ) {
  44                         // Unhandled API exception, we can't be sure that format printer is alive
  45                         self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
  46                         wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
  47                 } elseif ( self::isCommandLine() ) {
  48                         self::printError( self::getText( $e ) );
  49                 } elseif ( $mode === self::AS_PRETTY ) {
  50                         self::statusHeader( 500 );
  51                         if ( $e instanceof DBConnectionError ) {
  52                                 self::reportOutageHTML( $e );
  53                         } else {
  54                                 self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  55                                 self::reportHTML( $e );
  56                         }
  57                 } else {
  58                         if ( $eNew ) {
  59                                 $message = "MediaWiki internal error.\n\n";
  60                                 if ( self::showBackTrace( $e ) ) {
  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 ( self::showBackTrace( $e ) ) {
  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' ) {
  95                                 return false;
  96                         }
  97                 }
  98
  99                 return (
 100                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 101                         !empty( $GLOBALS['wgOut'] ) &&
 102                         !defined( 'MEDIAWIKI_INSTALL' )
 103                 );
 104         }
 105
 106         /**
 107          * Output the exception report using HTML
 108          *
 109          * @param Exception|Throwable $e
 110          */
 111         private static function reportHTML( $e ) {
 112                 global $wgOut, $wgSitename;
 113
 114                 if ( self::useOutputPage( $e ) ) {
 115                         if ( $e instanceof MWException ) {
 116                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 117                         } elseif ( $e instanceof DBReadOnlyError ) {
 118                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 119                         } elseif ( $e instanceof DBExpectedError ) {
 120                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 121                         } else {
 122                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 123                         }
 124
 125                         // Show any custom GUI message before the details
 126                         if ( $e instanceof MessageSpecifier ) {
 127                                 $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 128                         }
 129                         $wgOut->addHTML( self::getHTML( $e ) );
 130
 131                         $wgOut->output();
 132                 } else {
 133                         self::header( 'Content-Type: text/html; charset=utf-8' );
 134                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 135                         echo "<!DOCTYPE html>\n" .
 136                                 '<html><head>' .
 137                                 // Mimick OutputPage::setPageTitle behaviour
 138                                 '<title>' .
 139                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 140                                 '</title>' .
 141                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 142                                 "</head><body>\n";
 143
 144                         echo self::getHTML( $e );
 145
 146                         echo "</body></html>\n";
 147                 }
 148         }
 149
 150         /**
 151          * If $wgShowExceptionDetails is true, return a HTML message with a
 152          * backtrace to the error, otherwise show a message to ask to set it to true
 153          * to show that information.
 154          *
 155          * @param Exception|Throwable $e
 156          * @return string Html to output
 157          */
 158         public static function getHTML( $e ) {
 159                 if ( self::showBackTrace( $e ) ) {
 160                         $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
 161                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 162                                 '</p><p>Backtrace:</p><p>' .
 163                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 164                                 "</p></div>\n";
 165                 } else {
 166                         $logId = WebRequest::getRequestId();
 167                         $html = "<div class=\"errorbox mw-content-ltr\">" .
 168                                 '[' . $logId . '] ' .
 169                                 gmdate( 'Y-m-d H:i:s' ) . ": " .
 170                                 self::msg( "internalerror-fatal-exception",
 171                                         "Fatal exception of type $1",
 172                                         get_class( $e ),
 173                                         $logId,
 174                                         MWExceptionHandler::getURL()
 175                                 ) . "</div>\n" .
 176                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 177                 }
 178
 179                 return $html;
 180         }
 181
 182         /**
 183          * Get a message from i18n
 184          *
 185          * @param string $key Message name
 186          * @param string $fallback Default message if the message cache can't be
 187          *                  called by the exception
 188          * The function also has other parameters that are arguments for the message
 189          * @return string Message with arguments replaced
 190          */
 191         private static function msg( $key, $fallback /*[, params...] */ ) {
 192                 $args = array_slice( func_get_args(), 2 );
 193                 try {
 194                         return wfMessage( $key, $args )->text();
 195                 } catch ( Exception $e ) {
 196                         return wfMsgReplaceArgs( $fallback, $args );
 197                 }
 198         }
 199
 200         /**
 201          * @param Exception|Throwable $e
 202          * @return string
 203          */
 204         private static function getText( $e ) {
 205                 if ( self::showBackTrace( $e ) ) {
 206                         return MWExceptionHandler::getLogMessage( $e ) .
 207                                 "\nBacktrace:\n" .
 208                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 209                 } else {
 210                         return self::getShowBacktraceError( $e );
 211                 }
 212         }
 213
 214         /**
 215          * @param Exception|Throwable $e
 216          * @return bool
 217          */
 218         private static function showBackTrace( $e ) {
 219                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 220
 221                 return (
 222                         $wgShowExceptionDetails &&
 223                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 224                 );
 225         }
 226
 227         /**
 228          * @param Exception|Throwable $e
 229          * @return string
 230          */
 231         private static function getShowBacktraceError( $e ) {
 232                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 233                 $vars = [];
 234                 if ( !$wgShowExceptionDetails ) {
 235                         $vars[] = '$wgShowExceptionDetails = true;';
 236                 }
 237                 if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
 238                         $vars[] = '$wgShowDBErrorBacktrace = true;';
 239                 }
 240                 $vars = implode( ' and ', $vars );
 241                 return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information\n";
 242         }
 243
 244         /**
 245          * @return bool
 246          */
 247         private static function isCommandLine() {
 248                 return !empty( $GLOBALS['wgCommandLineMode'] );
 249         }
 250
 251         /**
 252          * @param string $header
 253          */
 254         private static function header( $header ) {
 255                 if ( !headers_sent() ) {
 256                         header( $header );
 257                 }
 258         }
 259
 260         /**
 261          * @param integer $code
 262          */
 263         private static function statusHeader( $code ) {
 264                 if ( !headers_sent() ) {
 265                         HttpStatus::header( $code );
 266                 }
 267         }
 268
 269         /**
 270          * Print a message, if possible to STDERR.
 271          * Use this in command line mode only (see isCommandLine)
 272          *
 273          * @param string $message Failure text
 274          */
 275         private static function printError( $message ) {
 276                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 277                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 278                 // echo may corrupt output to STDOUT though.
 279                 if ( defined( 'STDERR' ) ) {
 280                         fwrite( STDERR, $message );
 281                 } else {
 282                         echo $message;
 283                 }
 284         }
 285
 286         /**
 287          * @param Exception|Throwable $e
 288          */
 289         private static function reportOutageHTML( $e ) {
 290                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 291
 292                 $sorry = htmlspecialchars( self::msg(
 293                         'dberr-problems',
 294                         'Sorry! This site is experiencing technical difficulties.'
 295                 ) );
 296                 $again = htmlspecialchars( self::msg(
 297                         'dberr-again',
 298                         'Try waiting a few minutes and reloading.'
 299                 ) );
 300
 301                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 302                         $info = str_replace(
 303                                 '$1',
 304                                 Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
 305                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 306                         );
 307                 } else {
 308                         $info = htmlspecialchars( self::msg(
 309                                 'dberr-info-hidden',
 310                                 '(Cannot access the database)'
 311                         ) );
 312                 }
 313
 314                 MessageCache::singleton()->disable(); // no DB access
 315
 316                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 317
 318                 if ( $wgShowDBErrorBacktrace ) {
 319                         $html .= '<p>Backtrace:</p><pre>' .
 320                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 321                 }
 322
 323                 $html .= '<hr />';
 324                 $html .= self::googleSearchForm();
 325
 326                 echo $html;
 327         }
 328
 329         /**
 330          * @return string
 331          */
 332         private static function googleSearchForm() {
 333                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 334
 335                 $usegoogle = htmlspecialchars( self::msg(
 336                         'dberr-usegoogle',
 337                         'You can try searching via Google in the meantime.'
 338                 ) );
 339                 $outofdate = htmlspecialchars( self::msg(
 340                         'dberr-outofdate',
 341                         'Note that their indexes of our content may be out of date.'
 342                 ) );
 343                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 344                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 345                 $server = htmlspecialchars( $wgCanonicalServer );
 346                 $sitename = htmlspecialchars( $wgSitename );
 347                 $trygoogle = <<<EOT
 348 <div style="margin: 1.5em">$usegoogle<br />
 349 <small>$outofdate</small>
 350 </div>
 351 <form method="get" action="//www.google.com/search" id="googlesearch">
 352         <input type="hidden" name="domains" value="$server" />
 353         <input type="hidden" name="num" value="50" />
 354         <input type="hidden" name="ie" value="UTF-8" />
 355         <input type="hidden" name="oe" value="UTF-8" />
 356         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 357         <input type="submit" name="btnG" value="$googlesearch" />
 358         <p>
 359                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 360                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 361         </p>
 362 </form>
 363 EOT;
 364                 return $trygoogle;
 365         }
 366 }