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 .= 'Original exception: ' .
  64                                                 MWExceptionHandler::getPublicLogMessage( $e );
  65                                         $message .= "\n\nException caught inside exception handler.\n\n" .
  66                                                 self::getShowBacktraceError( $e );
  67                                 }
  68                                 $message .= "\n";
  69                         } else {
  70                                 if ( self::showBackTrace( $e ) ) {
  71                                         $message = MWExceptionHandler::getLogMessage( $e ) .
  72                                                 "\nBacktrace:\n" .
  73                                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
  74                                 } else {
  75                                         $message = MWExceptionHandler::getPublicLogMessage( $e );
  76                                 }
  77                         }
  78                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
  79                 }
  80         }
  81
  82         /**
  83          * Run hook to allow extensions to modify the text of the exception
  84          *
  85          * Called by MWException for b/c
  86          *
  87          * @param Exception|Throwable $e
  88          * @param string $name Class name of the exception
  89          * @param array $args Arguments to pass to the callback functions
  90          * @return string|null String to output or null if any hook has been called
  91          */
  92         public static function runHooks( $e, $name, $args = [] ) {
  93                 global $wgExceptionHooks;
  94
  95                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
  96                         return null; // Just silently ignore
  97                 }
  98
  99                 if ( !array_key_exists( $name, $wgExceptionHooks ) ||
 100                         !is_array( $wgExceptionHooks[$name] )
 101                 ) {
 102                         return null;
 103                 }
 104
 105                 $hooks = $wgExceptionHooks[$name];
 106                 $callargs = array_merge( [ $e ], $args );
 107
 108                 foreach ( $hooks as $hook ) {
 109                         if (
 110                                 is_string( $hook ) ||
 111                                 ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
 112                         ) {
 113                                 // 'function' or [ 'class', 'hook' ]
 114                                 $result = call_user_func_array( $hook, $callargs );
 115                         } else {
 116                                 $result = null;
 117                         }
 118
 119                         if ( is_string( $result ) ) {
 120                                 return $result;
 121                         }
 122                 }
 123
 124                 return null;
 125         }
 126
 127         /**
 128          * @param Exception|Throwable $e
 129          * @return bool Should the exception use $wgOut to output the error?
 130          */
 131         private static function useOutputPage( $e ) {
 132                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
 133                 foreach ( $e->getTrace() as $frame ) {
 134                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
 135                                 return false;
 136                         }
 137                 }
 138
 139                 return (
 140                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 141                         !empty( $GLOBALS['wgOut'] ) &&
 142                         !defined( 'MEDIAWIKI_INSTALL' )
 143                 );
 144         }
 145
 146         /**
 147          * Output the exception report using HTML
 148          *
 149          * @param Exception|Throwable $e
 150          */
 151         private static function reportHTML( $e ) {
 152                 global $wgOut, $wgSitename;
 153
 154                 if ( self::useOutputPage( $e ) ) {
 155                         if ( $e instanceof MWException ) {
 156                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 157                         } elseif ( $e instanceof DBReadOnlyError ) {
 158                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 159                         } elseif ( $e instanceof DBExpectedError ) {
 160                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 161                         } else {
 162                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 163                         }
 164
 165                         $hookResult = self::runHooks( $e, get_class( $e ) );
 166                         if ( $hookResult ) {
 167                                 $wgOut->addHTML( $hookResult );
 168                         } else {
 169                                 // Show any custom GUI message before the details
 170                                 if ( $e instanceof MessageSpecifier ) {
 171                                         $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 172                                 }
 173                                 $wgOut->addHTML( self::getHTML( $e ) );
 174                         }
 175
 176                         $wgOut->output();
 177                 } else {
 178                         self::header( 'Content-Type: text/html; charset=utf-8' );
 179                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 180                         echo "<!DOCTYPE html>\n" .
 181                                 '<html><head>' .
 182                                 // Mimick OutputPage::setPageTitle behaviour
 183                                 '<title>' .
 184                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 185                                 '</title>' .
 186                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 187                                 "</head><body>\n";
 188
 189                         $hookResult = self::runHooks( $e, get_class( $e ) . 'Raw' );
 190                         if ( $hookResult ) {
 191                                 echo $hookResult;
 192                         } else {
 193                                 echo self::getHTML( $e );
 194                         }
 195
 196                         echo "</body></html>\n";
 197                 }
 198         }
 199
 200         /**
 201          * If $wgShowExceptionDetails is true, return a HTML message with a
 202          * backtrace to the error, otherwise show a message to ask to set it to true
 203          * to show that information.
 204          *
 205          * @param Exception|Throwable $e
 206          * @return string Html to output
 207          */
 208         public static function getHTML( $e ) {
 209                 if ( self::showBackTrace( $e ) ) {
 210                         $html = "<div class=\"errorbox\"><p>" .
 211                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 212                                 '</p><p>Backtrace:</p><p>' .
 213                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 214                                 "</p></div>\n";
 215                 } else {
 216                         $logId = WebRequest::getRequestId();
 217                         $html = "<div class=\"errorbox\">" .
 218                                 '[' . $logId . '] ' .
 219                                 gmdate( 'Y-m-d H:i:s' ) . ": " .
 220                                 self::msg( "internalerror-fatal-exception",
 221                                         "Fatal exception of type $1",
 222                                         get_class( $e ),
 223                                         $logId,
 224                                         MWExceptionHandler::getURL()
 225                                 ) . "</div>\n" .
 226                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 227                 }
 228
 229                 return $html;
 230         }
 231
 232         /**
 233          * Get a message from i18n
 234          *
 235          * @param string $key Message name
 236          * @param string $fallback Default message if the message cache can't be
 237          *                  called by the exception
 238          * The function also has other parameters that are arguments for the message
 239          * @return string Message with arguments replaced
 240          */
 241         private static function msg( $key, $fallback /*[, params...] */ ) {
 242                 $args = array_slice( func_get_args(), 2 );
 243                 try {
 244                         return wfMessage( $key, $args )->text();
 245                 } catch ( Exception $e ) {
 246                         return wfMsgReplaceArgs( $fallback, $args );
 247                 }
 248         }
 249
 250         /**
 251          * @param Exception|Throwable $e
 252          * @return string
 253          */
 254         private static function getText( $e ) {
 255                 if ( self::showBackTrace( $e ) ) {
 256                         return MWExceptionHandler::getLogMessage( $e ) .
 257                                 "\nBacktrace:\n" .
 258                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 259                 } else {
 260                         return self::getShowBacktraceError( $e );
 261                 }
 262         }
 263
 264         /**
 265          * @param Exception|Throwable $e
 266          * @return bool
 267          */
 268         private static function showBackTrace( $e ) {
 269                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 270
 271                 return (
 272                         $wgShowExceptionDetails &&
 273                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 274                 );
 275         }
 276
 277         /**
 278          * @param Exception|Throwable $e
 279          * @return string
 280          */
 281         private static function getShowBacktraceError( $e ) {
 282                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 283                 $vars = [];
 284                 if ( !$wgShowExceptionDetails ) {
 285                         $vars[] = '$wgShowExceptionDetails = true;';
 286                 }
 287                 if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
 288                         $vars[] = '$wgShowDBErrorBacktrace = true;';
 289                 }
 290                 $vars = implode( ' and ', $vars );
 291                 return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information";
 292         }
 293
 294         /**
 295          * @return bool
 296          */
 297         private static function isCommandLine() {
 298                 return !empty( $GLOBALS['wgCommandLineMode'] );
 299         }
 300
 301         /**
 302          * @param string $header
 303          */
 304         private static function header( $header ) {
 305                 if ( !headers_sent() ) {
 306                         header( $header );
 307                 }
 308         }
 309
 310         /**
 311          * @param integer $code
 312          */
 313         private static function statusHeader( $code ) {
 314                 if ( !headers_sent() ) {
 315                         HttpStatus::header( $code );
 316                 }
 317         }
 318
 319         /**
 320          * Print a message, if possible to STDERR.
 321          * Use this in command line mode only (see isCommandLine)
 322          *
 323          * @param string $message Failure text
 324          */
 325         private static function printError( $message ) {
 326                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 327                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 328                 // echo may corrupt output to STDOUT though.
 329                 if ( defined( 'STDERR' ) ) {
 330                         fwrite( STDERR, $message );
 331                 } else {
 332                         echo $message;
 333                 }
 334         }
 335
 336         /**
 337          * @param Exception|Throwable $e
 338          */
 339         private static function reportOutageHTML( $e ) {
 340                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 341
 342                 $sorry = htmlspecialchars( self::msg(
 343                         'dberr-problems',
 344                         'Sorry! This site is experiencing technical difficulties.'
 345                 ) );
 346                 $again = htmlspecialchars( self::msg(
 347                         'dberr-again',
 348                         'Try waiting a few minutes and reloading.'
 349                 ) );
 350
 351                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 352                         $info = str_replace(
 353                                 '$1',
 354                                 Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
 355                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 356                         );
 357                 } else {
 358                         $info = htmlspecialchars( self::msg(
 359                                 'dberr-info-hidden',
 360                                 '(Cannot access the database)'
 361                         ) );
 362                 }
 363
 364                 MessageCache::singleton()->disable(); // no DB access
 365
 366                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 367
 368                 if ( $wgShowDBErrorBacktrace ) {
 369                         $html .= '<p>Backtrace:</p><pre>' .
 370                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 371                 }
 372
 373                 $html .= '<hr />';
 374                 $html .= self::googleSearchForm();
 375
 376                 echo $html;
 377         }
 378
 379         /**
 380          * @return string
 381          */
 382         private static function googleSearchForm() {
 383                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 384
 385                 $usegoogle = htmlspecialchars( self::msg(
 386                         'dberr-usegoogle',
 387                         'You can try searching via Google in the meantime.'
 388                 ) );
 389                 $outofdate = htmlspecialchars( self::msg(
 390                         'dberr-outofdate',
 391                         'Note that their indexes of our content may be out of date.'
 392                 ) );
 393                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 394                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 395                 $server = htmlspecialchars( $wgCanonicalServer );
 396                 $sitename = htmlspecialchars( $wgSitename );
 397                 $trygoogle = <<<EOT
 398 <div style="margin: 1.5em">$usegoogle<br />
 399 <small>$outofdate</small>
 400 </div>
 401 <form method="get" action="//www.google.com/search" id="googlesearch">
 402         <input type="hidden" name="domains" value="$server" />
 403         <input type="hidden" name="num" value="50" />
 404         <input type="hidden" name="ie" value="UTF-8" />
 405         <input type="hidden" name="oe" value="UTF-8" />
 406         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 407         <input type="submit" name="btnG" value="$googlesearch" />
 408         <p>
 409                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 410                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 411         </p>
 412 </form>
 413 EOT;
 414                 return $trygoogle;
 415         }
 416 }