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