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                         if ( self::isCommandLine() ) {
  77                                 self::printError( $message );
  78                         } else {
  79                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
  80                         }
  81                 }
  82         }
  83
  84         /**
  85          * Run hook to allow extensions to modify the text of the exception
  86          *
  87          * Called by MWException for b/c
  88          *
  89          * @param Exception|Throwable $e
  90          * @param string $name Class name of the exception
  91          * @param array $args Arguments to pass to the callback functions
  92          * @return string|null String to output or null if any hook has been called
  93          */
  94         public static function runHooks( $e, $name, $args = [] ) {
  95                 global $wgExceptionHooks;
  96
  97                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
  98                         return null; // Just silently ignore
  99                 }
 100
 101                 if ( !array_key_exists( $name, $wgExceptionHooks ) ||
 102                         !is_array( $wgExceptionHooks[$name] )
 103                 ) {
 104                         return null;
 105                 }
 106
 107                 $hooks = $wgExceptionHooks[$name];
 108                 $callargs = array_merge( [ $e ], $args );
 109
 110                 foreach ( $hooks as $hook ) {
 111                         if (
 112                                 is_string( $hook ) ||
 113                                 ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
 114                         ) {
 115                                 // 'function' or [ 'class', 'hook' ]
 116                                 $result = call_user_func_array( $hook, $callargs );
 117                         } else {
 118                                 $result = null;
 119                         }
 120
 121                         if ( is_string( $result ) ) {
 122                                 return $result;
 123                         }
 124                 }
 125
 126                 return null;
 127         }
 128
 129         /**
 130          * @param Exception|Throwable $e
 131          * @return bool Should the exception use $wgOut to output the error?
 132          */
 133         private static function useOutputPage( $e ) {
 134                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
 135                 foreach ( $e->getTrace() as $frame ) {
 136                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
 137                                 return false;
 138                         }
 139                 }
 140
 141                 return (
 142                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 143                         !empty( $GLOBALS['wgOut'] ) &&
 144                         !defined( 'MEDIAWIKI_INSTALL' )
 145                 );
 146         }
 147
 148         /**
 149          * Output the exception report using HTML
 150          *
 151          * @param Exception|Throwable $e
 152          */
 153         private static function reportHTML( $e ) {
 154                 global $wgOut, $wgSitename;
 155
 156                 if ( self::useOutputPage( $e ) ) {
 157                         if ( $e instanceof MWException ) {
 158                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 159                         } elseif ( $e instanceof DBReadOnlyError ) {
 160                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 161                         } elseif ( $e instanceof DBExpectedError ) {
 162                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 163                         } else {
 164                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 165                         }
 166
 167                         $hookResult = self::runHooks( $e, get_class( $e ) );
 168                         if ( $hookResult ) {
 169                                 $wgOut->addHTML( $hookResult );
 170                         } else {
 171                                 // Show any custom GUI message before the details
 172                                 if ( $e instanceof MessageSpecifier ) {
 173                                         $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
 174                                 }
 175                                 $wgOut->addHTML( self::getHTML( $e ) );
 176                         }
 177
 178                         $wgOut->output();
 179                 } else {
 180                         self::header( 'Content-Type: text/html; charset=utf-8' );
 181                         $pageTitle = self::msg( 'internalerror', 'Internal error' );
 182                         echo "<!DOCTYPE html>\n" .
 183                                 '<html><head>' .
 184                                 // Mimick OutputPage::setPageTitle behaviour
 185                                 '<title>' .
 186                                 htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
 187                                 '</title>' .
 188                                 '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
 189                                 "</head><body>\n";
 190
 191                         $hookResult = self::runHooks( $e, get_class( $e ) . 'Raw' );
 192                         if ( $hookResult ) {
 193                                 echo $hookResult;
 194                         } else {
 195                                 echo self::getHTML( $e );
 196                         }
 197
 198                         echo "</body></html>\n";
 199                 }
 200         }
 201
 202         /**
 203          * If $wgShowExceptionDetails is true, return a HTML message with a
 204          * backtrace to the error, otherwise show a message to ask to set it to true
 205          * to show that information.
 206          *
 207          * @param Exception|Throwable $e
 208          * @return string Html to output
 209          */
 210         public static function getHTML( $e ) {
 211                 if ( self::showBackTrace( $e ) ) {
 212                         $html = "<div class=\"errorbox\"><p>" .
 213                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 214                                 '</p><p>Backtrace:</p><p>' .
 215                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 216                                 "</p></div>\n";
 217                 } else {
 218                         $logId = WebRequest::getRequestId();
 219                         $html = "<div class=\"errorbox\">" .
 220                                 '[' . $logId . '] ' .
 221                                 gmdate( 'Y-m-d H:i:s' ) . ": " .
 222                                 self::msg( "internalerror-fatal-exception",
 223                                         "Fatal exception of type $1",
 224                                         get_class( $e ),
 225                                         $logId,
 226                                         MWExceptionHandler::getURL()
 227                                 ) . "</div>\n" .
 228                                 "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
 229                 }
 230
 231                 return $html;
 232         }
 233
 234         /**
 235          * Get a message from i18n
 236          *
 237          * @param string $key Message name
 238          * @param string $fallback Default message if the message cache can't be
 239          *                  called by the exception
 240          * The function also has other parameters that are arguments for the message
 241          * @return string Message with arguments replaced
 242          */
 243         private static function msg( $key, $fallback /*[, params...] */ ) {
 244                 $args = array_slice( func_get_args(), 2 );
 245                 try {
 246                         return wfMessage( $key, $args )->text();
 247                 } catch ( Exception $e ) {
 248                         return wfMsgReplaceArgs( $fallback, $args );
 249                 }
 250         }
 251
 252         /**
 253          * @param Exception|Throwable $e
 254          * @return string
 255          */
 256         private static function getText( $e ) {
 257                 if ( self::showBackTrace( $e ) ) {
 258                         return MWExceptionHandler::getLogMessage( $e ) .
 259                                 "\nBacktrace:\n" .
 260                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 261                 } else {
 262                         return self::getShowBacktraceError( $e );
 263                 }
 264         }
 265
 266         /**
 267          * @param Exception|Throwable $e
 268          * @return bool
 269          */
 270         private static function showBackTrace( $e ) {
 271                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 272
 273                 return (
 274                         $wgShowExceptionDetails &&
 275                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 276                 );
 277         }
 278
 279         /**
 280          * @param Exception|Throwable $e
 281          * @return string
 282          */
 283         private static function getShowBacktraceError( $e ) {
 284                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 285                 $vars = [];
 286                 if ( !$wgShowExceptionDetails ) {
 287                         $vars[] = '$wgShowExceptionDetails = true;';
 288                 }
 289                 if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
 290                         $vars[] = '$wgShowDBErrorBacktrace = true;';
 291                 }
 292                 $vars = implode( ' and ', $vars );
 293                 return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information";
 294         }
 295
 296         /**
 297          * @return bool
 298          */
 299         private static function isCommandLine() {
 300                 return !empty( $GLOBALS['wgCommandLineMode'] );
 301         }
 302
 303         /**
 304          * @param string $header
 305          */
 306         private static function header( $header ) {
 307                 if ( !headers_sent() ) {
 308                         header( $header );
 309                 }
 310         }
 311
 312         /**
 313          * @param integer $code
 314          */
 315         private static function statusHeader( $code ) {
 316                 if ( !headers_sent() ) {
 317                         HttpStatus::header( $code );
 318                 }
 319         }
 320
 321         /**
 322          * Print a message, if possible to STDERR.
 323          * Use this in command line mode only (see isCommandLine)
 324          *
 325          * @param string $message Failure text
 326          */
 327         private static function printError( $message ) {
 328                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 329                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 330                 // echo may corrupt output to STDOUT though.
 331                 if ( defined( 'STDERR' ) ) {
 332                         fwrite( STDERR, $message );
 333                 } else {
 334                         echo $message;
 335                 }
 336         }
 337
 338         /**
 339          * @param Exception|Throwable $e
 340          */
 341         private static function reportOutageHTML( $e ) {
 342                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 343
 344                 $sorry = htmlspecialchars( self::msg(
 345                         'dberr-problems',
 346                         'Sorry! This site is experiencing technical difficulties.'
 347                 ) );
 348                 $again = htmlspecialchars( self::msg(
 349                         'dberr-again',
 350                         'Try waiting a few minutes and reloading.'
 351                 ) );
 352
 353                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 354                         $info = str_replace(
 355                                 '$1',
 356                                 Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
 357                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 358                         );
 359                 } else {
 360                         $info = htmlspecialchars( self::msg(
 361                                 'dberr-info-hidden',
 362                                 '(Cannot access the database)'
 363                         ) );
 364                 }
 365
 366                 MessageCache::singleton()->disable(); // no DB access
 367
 368                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 369
 370                 if ( $wgShowDBErrorBacktrace ) {
 371                         $html .= '<p>Backtrace:</p><pre>' .
 372                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 373                 }
 374
 375                 $html .= '<hr />';
 376                 $html .= self::googleSearchForm();
 377
 378                 echo $html;
 379         }
 380
 381         /**
 382          * @return string
 383          */
 384         private static function googleSearchForm() {
 385                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 386
 387                 $usegoogle = htmlspecialchars( self::msg(
 388                         'dberr-usegoogle',
 389                         'You can try searching via Google in the meantime.'
 390                 ) );
 391                 $outofdate = htmlspecialchars( self::msg(
 392                         'dberr-outofdate',
 393                         'Note that their indexes of our content may be out of date.'
 394                 ) );
 395                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 396                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 397                 $server = htmlspecialchars( $wgCanonicalServer );
 398                 $sitename = htmlspecialchars( $wgSitename );
 399                 $trygoogle = <<<EOT
 400 <div style="margin: 1.5em">$usegoogle<br />
 401 <small>$outofdate</small>
 402 </div>
 403 <form method="get" action="//www.google.com/search" id="googlesearch">
 404         <input type="hidden" name="domains" value="$server" />
 405         <input type="hidden" name="num" value="50" />
 406         <input type="hidden" name="ie" value="UTF-8" />
 407         <input type="hidden" name="oe" value="UTF-8" />
 408         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 409         <input type="submit" name="btnG" value="$googlesearch" />
 410         <p>
 411                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 412                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 413         </p>
 414 </form>
 415 EOT;
 416                 return $trygoogle;
 417         }
 418 }