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 /**
  23  * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
  24  * @since 1.28
  25  */
  26 class MWExceptionRenderer {
  27         const AS_RAW = 1; // show as text
  28         const AS_PRETTY = 2; // show as HTML
  29
  30         /**
  31          * @param Exception|Throwable $e Original exception
  32          * @param integer $mode MWExceptionExposer::AS_* constant
  33          * @param Exception|Throwable|null $eNew New exception from attempting to show the first
  34          */
  35         public static function output( $e, $mode, $eNew = null ) {
  36                 global $wgMimeType;
  37
  38                 if ( defined( 'MW_API' ) ) {
  39                         // Unhandled API exception, we can't be sure that format printer is alive
  40                         self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
  41                         wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
  42                 } elseif ( self::isCommandLine() ) {
  43                         self::printError( self::getText( $e ) );
  44                 } elseif ( $mode === self::AS_PRETTY ) {
  45                         if ( $e instanceof DBConnectionError ) {
  46                                 self::reportOutageHTML( $e );
  47                         } else {
  48                                 self::statusHeader( 500 );
  49                                 self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  50                                 self::reportHTML( $e );
  51                         }
  52                 } else {
  53                         if ( $eNew ) {
  54                                 $message = "MediaWiki internal error.\n\n";
  55                                 if ( self::showBackTrace( $e ) ) {
  56                                         $message .= 'Original exception: ' .
  57                                                 MWExceptionHandler::getLogMessage( $e ) .
  58                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
  59                                                 "\n\nException caught inside exception handler: " .
  60                                                         MWExceptionHandler::getLogMessage( $eNew ) .
  61                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
  62                                 } else {
  63                                         $message .= "Exception caught inside exception handler.\n\n" .
  64                                                 "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
  65                                                 "to show detailed debugging information.";
  66                                 }
  67                                 $message .= "\n";
  68                         } else {
  69                                 if ( self::showBackTrace( $e ) ) {
  70                                         $message = MWExceptionHandler::getLogMessage( $e ) .
  71                                                 "\nBacktrace:\n" .
  72                                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  73                                 } else {
  74                                         $message = MWExceptionHandler::getPublicLogMessage( $e );
  75                                 }
  76                         }
  77                         if ( self::isCommandLine() ) {
  78                                 self::printError( $message );
  79                         } else {
  80                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
  81                         }
  82                 }
  83         }
  84
  85         /**
  86          * Run hook to allow extensions to modify the text of the exception
  87          *
  88          * Called by MWException for b/c
  89          *
  90          * @param Exception|Throwable $e
  91          * @param string $name Class name of the exception
  92          * @param array $args Arguments to pass to the callback functions
  93          * @return string|null String to output or null if any hook has been called
  94          */
  95         public static function runHooks( $e, $name, $args = [] ) {
  96                 global $wgExceptionHooks;
  97
  98                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
  99                         return null; // Just silently ignore
 100                 }
 101
 102                 if ( !array_key_exists( $name, $wgExceptionHooks ) ||
 103                         !is_array( $wgExceptionHooks[$name] )
 104                 ) {
 105                         return null;
 106                 }
 107
 108                 $hooks = $wgExceptionHooks[$name];
 109                 $callargs = array_merge( [ $e ], $args );
 110
 111                 foreach ( $hooks as $hook ) {
 112                         if (
 113                                 is_string( $hook ) ||
 114                                 ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
 115                         ) {
 116                                 // 'function' or [ 'class', 'hook' ]
 117                                 $result = call_user_func_array( $hook, $callargs );
 118                         } else {
 119                                 $result = null;
 120                         }
 121
 122                         if ( is_string( $result ) ) {
 123                                 return $result;
 124                         }
 125                 }
 126
 127                 return null;
 128         }
 129
 130         /**
 131          * @param Exception|Throwable $e
 132          * @return bool Should the exception use $wgOut to output the error?
 133          */
 134         private static function useOutputPage( $e ) {
 135                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
 136                 foreach ( $e->getTrace() as $frame ) {
 137                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
 138                                 return false;
 139                         }
 140                 }
 141
 142                 return (
 143                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 144                         !empty( $GLOBALS['wgOut'] ) &&
 145                         !defined( 'MEDIAWIKI_INSTALL' )
 146                 );
 147         }
 148
 149         /**
 150          * Output the exception report using HTML
 151          *
 152          * @param Exception|Throwable $e
 153          */
 154         private static function reportHTML( $e ) {
 155                 global $wgOut, $wgSitename;
 156
 157                 if ( self::useOutputPage( $e ) ) {
 158                         if ( $e instanceof MWException ) {
 159                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 160                         } elseif ( $e instanceof DBReadOnlyError ) {
 161                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 162                         } elseif ( $e instanceof DBExpectedError ) {
 163                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 164                         } else {
 165                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 166                         }
 167
 168                         $hookResult = self::runHooks( $e, get_class( $e ) );
 169                         if ( $hookResult ) {
 170                                 $wgOut->addHTML( $hookResult );
 171                         } else {
 172                                 // Show any custom GUI message before the details
 173                                 if ( $e instanceof MessageSpecifier ) {
 174                                         $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 175                                 }
 176                                 $wgOut->addHTML( self::getHTML( $e ) );
 177                         }
 178
 179                         $wgOut->output();
 180                 } else {
 181                         self::header( 'Content-Type: text/html; charset=utf-8' );
 182                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 183                         echo "<!DOCTYPE html>\n" .
 184                                 '<html><head>' .
 185                                 // Mimick OutputPage::setPageTitle behaviour
 186                                 '<title>' .
 187                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 188                                 '</title>' .
 189                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 190                                 "</head><body>\n";
 191
 192                         $hookResult = self::runHooks( $e, get_class( $e ) . 'Raw' );
 193                         if ( $hookResult ) {
 194                                 echo $hookResult;
 195                         } else {
 196                                 echo self::getHTML( $e );
 197                         }
 198
 199                         echo "</body></html>\n";
 200                 }
 201         }
 202
 203         /**
 204          * If $wgShowExceptionDetails is true, return a HTML message with a
 205          * backtrace to the error, otherwise show a message to ask to set it to true
 206          * to show that information.
 207          *
 208          * @param Exception|Throwable $e
 209          * @return string Html to output
 210          */
 211         public static function getHTML( $e ) {
 212                 if ( self::showBackTrace( $e ) ) {
 213                         $html = "<div class=\"errorbox\"><p>" .
 214                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 215                                 '</p><p>Backtrace:</p><p>' .
 216                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 217                                 "</p></div>\n";
 218                 } else {
 219                         $logId = WebRequest::getRequestId();
 220                         $html = "<div class=\"errorbox\">" .
 221                                 '[' . $logId . '] ' .
 222                                 gmdate( 'Y-m-d H:i:s' ) . ": " .
 223                                 self::msg( "internalerror-fatal-exception",
 224                                         "Fatal exception of type $1",
 225                                         get_class( $e ),
 226                                         $logId,
 227                                         MWExceptionHandler::getURL()
 228                                 ) . "</div>\n" .
 229                         "<!-- Set \$wgShowExceptionDetails = true; " .
 230                         "at the bottom of LocalSettings.php to show detailed " .
 231                         "debugging information. -->";
 232                 }
 233
 234                 return $html;
 235         }
 236
 237         /**
 238          * Get a message from i18n
 239          *
 240          * @param string $key Message name
 241          * @param string $fallback Default message if the message cache can't be
 242          *                  called by the exception
 243          * The function also has other parameters that are arguments for the message
 244          * @return string Message with arguments replaced
 245          */
 246         private static function msg( $key, $fallback /*[, params...] */ ) {
 247                 $args = array_slice( func_get_args(), 2 );
 248                 try {
 249                         return wfMessage( $key, $args )->text();
 250                 } catch ( Exception $e ) {
 251                         return wfMsgReplaceArgs( $fallback, $args );
 252                 }
 253         }
 254
 255         /**
 256          * @param Exception|Throwable $e
 257          * @return string
 258          */
 259         private static function getText( $e ) {
 260                 if ( self::showBackTrace( $e ) ) {
 261                         return MWExceptionHandler::getLogMessage( $e ) .
 262                                 "\nBacktrace:\n" .
 263                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 264                 } else {
 265                         return "Set \$wgShowExceptionDetails = true; " .
 266                                 "in LocalSettings.php to show detailed debugging information.\n";
 267                 }
 268         }
 269
 270         /**
 271          * @param Exception|Throwable $e
 272          * @return bool
 273          */
 274         private static function showBackTrace( $e ) {
 275                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 276
 277                 return (
 278                         $wgShowExceptionDetails &&
 279                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 280                 );
 281         }
 282
 283         /**
 284          * @return bool
 285          */
 286         private static function isCommandLine() {
 287                 return !empty( $GLOBALS['wgCommandLineMode'] );
 288         }
 289
 290         /**
 291          * @param string $header
 292          */
 293         private static function header( $header ) {
 294                 if ( !headers_sent() ) {
 295                         header( $header );
 296                 }
 297         }
 298
 299         /**
 300          * @param integer $code
 301          */
 302         private static function statusHeader( $code ) {
 303                 if ( !headers_sent() ) {
 304                         HttpStatus::header( $code );
 305                 }
 306         }
 307
 308         /**
 309          * Print a message, if possible to STDERR.
 310          * Use this in command line mode only (see isCommandLine)
 311          *
 312          * @param string $message Failure text
 313          */
 314         private static function printError( $message ) {
 315                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 316                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 317                 // echo may corrupt output to STDOUT though.
 318                 if ( defined( 'STDERR' ) ) {
 319                         fwrite( STDERR, $message );
 320                 } else {
 321                         echo $message;
 322                 }
 323         }
 324
 325         /**
 326          * @param Exception|Throwable $e
 327          */
 328         private static function reportOutageHTML( $e ) {
 329                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 330
 331                 $sorry = htmlspecialchars( self::msg(
 332                         'dberr-problems',
 333                         'Sorry! This site is experiencing technical difficulties.'
 334                 ) );
 335                 $again = htmlspecialchars( self::msg(
 336                         'dberr-again',
 337                         'Try waiting a few minutes and reloading.'
 338                 ) );
 339
 340                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 341                         $info = str_replace(
 342                                 '$1',
 343                                 Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
 344                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 345                         );
 346                 } else {
 347                         $info = htmlspecialchars( self::msg(
 348                                 'dberr-info-hidden',
 349                                 '(Cannot access the database)'
 350                         ) );
 351                 }
 352
 353                 MessageCache::singleton()->disable(); // no DB access
 354
 355                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 356
 357                 if ( $wgShowDBErrorBacktrace ) {
 358                         $html .= '<p>Backtrace:</p><pre>' .
 359                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 360                 }
 361
 362                 $html .= '<hr />';
 363                 $html .= self::googleSearchForm();
 364
 365                 echo $html;
 366         }
 367
 368         /**
 369          * @return string
 370          */
 371         private static function googleSearchForm() {
 372                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 373
 374                 $usegoogle = htmlspecialchars( self::msg(
 375                         'dberr-usegoogle',
 376                         'You can try searching via Google in the meantime.'
 377                 ) );
 378                 $outofdate = htmlspecialchars( self::msg(
 379                         'dberr-outofdate',
 380                         'Note that their indexes of our content may be out of date.'
 381                 ) );
 382                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 383                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 384                 $server = htmlspecialchars( $wgCanonicalServer );
 385                 $sitename = htmlspecialchars( $wgSitename );
 386                 $trygoogle = <<<EOT
 387 <div style="margin: 1.5em">$usegoogle<br />
 388 <small>$outofdate</small>
 389 </div>
 390 <form method="get" action="//www.google.com/search" id="googlesearch">
 391         <input type="hidden" name="domains" value="$server" />
 392         <input type="hidden" name="num" value="50" />
 393         <input type="hidden" name="ie" value="UTF-8" />
 394         <input type="hidden" name="oe" value="UTF-8" />
 395         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 396         <input type="submit" name="btnG" value="$googlesearch" />
 397         <p>
 398                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 399                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 400         </p>
 401 </form>
 402 EOT;
 403                 return $trygoogle;
 404         }
 405 }