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 $e Original exception
  32          * @param integer $mode MWExceptionExposer::AS_* constant
  33          * @param Exception|null $eNew New exception from attempting to show the first
  34          */
  35         public static function output( Exception $e, $mode, Exception $eNew = null ) {
  36                 global $wgMimeType;
  37
  38                 if ( $e instanceof DBConnectionError ) {
  39                         self::reportOutageHTML( $e );
  40                         return;
  41                 }
  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                         self::header( "Content-Type: $wgMimeType; charset=utf-8" );
  52                         self::reportHTML( $e );
  53                 } else {
  54                         if ( $eNew ) {
  55                                 $message = "MediaWiki internal error.\n\n";
  56                                 if ( self::showBackTrace( $e ) ) {
  57                                         $message .= 'Original exception: ' .
  58                                                 MWExceptionHandler::getLogMessage( $e ) .
  59                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
  60                                                 "\n\nException caught inside exception handler: " .
  61                                                         MWExceptionHandler::getLogMessage( $eNew ) .
  62                                                 "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
  63                                 } else {
  64                                         $message .= "Exception caught inside exception handler.\n\n" .
  65                                                 "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
  66                                                 "to show detailed debugging information.";
  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                         if ( self::isCommandLine() ) {
  79                                 self::printError( $message );
  80                         } else {
  81                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
  82                         }
  83                 }
  84         }
  85
  86         /**
  87          * Run hook to allow extensions to modify the text of the exception
  88          *
  89          * Called by MWException for b/c
  90          *
  91          * @param Exception $e
  92          * @param string $name Class name of the exception
  93          * @param array $args Arguments to pass to the callback functions
  94          * @return string|null String to output or null if any hook has been called
  95          */
  96         public static function runHooks( Exception $e, $name, $args = [] ) {
  97                 global $wgExceptionHooks;
  98
  99                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
 100                         return null; // Just silently ignore
 101                 }
 102
 103                 if ( !array_key_exists( $name, $wgExceptionHooks ) ||
 104                         !is_array( $wgExceptionHooks[$name] )
 105                 ) {
 106                         return null;
 107                 }
 108
 109                 $hooks = $wgExceptionHooks[$name];
 110                 $callargs = array_merge( [ $e ], $args );
 111
 112                 foreach ( $hooks as $hook ) {
 113                         if (
 114                                 is_string( $hook ) ||
 115                                 ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
 116                         ) {
 117                                 // 'function' or [ 'class', 'hook' ]
 118                                 $result = call_user_func_array( $hook, $callargs );
 119                         } else {
 120                                 $result = null;
 121                         }
 122
 123                         if ( is_string( $result ) ) {
 124                                 return $result;
 125                         }
 126                 }
 127
 128                 return null;
 129         }
 130
 131         /**
 132          * @param Exception $e
 133          * @return bool Should the exception use $wgOut to output the error?
 134          */
 135         private static function useOutputPage( Exception $e ) {
 136                 // Can the extension use the Message class/wfMessage to get i18n-ed messages?
 137                 $useMessageCache = ( $GLOBALS['wgLang'] instanceof Language );
 138                 foreach ( $e->getTrace() as $frame ) {
 139                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
 140                                 $useMessageCache = false;
 141                         }
 142                 }
 143
 144                 return (
 145                         $useMessageCache &&
 146                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
 147                         !empty( $GLOBALS['wgOut'] ) &&
 148                         !defined( 'MEDIAWIKI_INSTALL' )
 149                 );
 150         }
 151
 152         /**
 153          * Output the exception report using HTML
 154          *
 155          * @param Exception $e
 156          */
 157         private static function reportHTML( Exception $e ) {
 158                 global $wgOut, $wgSitename;
 159
 160                 if ( self::useOutputPage( $e ) ) {
 161                         if ( $e instanceof MWException ) {
 162                                 $wgOut->prepareErrorPage( $e->getPageTitle() );
 163                         } elseif ( $e instanceof DBReadOnlyError ) {
 164                                 $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
 165                         } elseif ( $e instanceof DBExpectedError ) {
 166                                 $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
 167                         } else {
 168                                 $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
 169                         }
 170
 171                         $hookResult = self::runHooks( $e, get_class( $e ) );
 172                         if ( $hookResult ) {
 173                                 $wgOut->addHTML( $hookResult );
 174                         } else {
 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 $e
 208          * @return string Html to output
 209          */
 210         private static function getHTML( Exception $e ) {
 211                 if ( self::showBackTrace( $e ) ) {
 212                         return '<p>' .
 213                                 nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
 214                                 '</p><p>Backtrace:</p><p>' .
 215                                 nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
 216                                 "</p>\n";
 217                 } else {
 218                         $logId = WebRequest::getRequestId();
 219                         return "<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                         "<!-- Set \$wgShowExceptionDetails = true; " .
 229                         "at the bottom of LocalSettings.php to show detailed " .
 230                         "debugging information. -->";
 231                 }
 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 $e
 254          * @return string
 255          */
 256         private function getText( Exception $e ) {
 257                 if ( self::showBackTrace( $e ) ) {
 258                         return MWExceptionHandler::getLogMessage( $e ) .
 259                                 "\nBacktrace:\n" .
 260                                 MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
 261                 } else {
 262                         return "Set \$wgShowExceptionDetails = true; " .
 263                                 "in LocalSettings.php to show detailed debugging information.\n";
 264                 }
 265         }
 266
 267         /**
 268          * @param Exception $e
 269          * @return bool
 270          */
 271         private static function showBackTrace( Exception $e ) {
 272                 global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
 273
 274                 return (
 275                         $wgShowExceptionDetails &&
 276                         ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
 277                 );
 278         }
 279
 280         /**
 281          * @return bool
 282          */
 283         private static function isCommandLine() {
 284                 return !empty( $GLOBALS['wgCommandLineMode'] );
 285         }
 286
 287         /**
 288          * @param string $header
 289          */
 290         private static function header( $header ) {
 291                 if ( !headers_sent() ) {
 292                         header( $header );
 293                 }
 294         }
 295
 296         /**
 297          * @param integer $code
 298          */
 299         private static function statusHeader( $code ) {
 300                 if ( !headers_sent() ) {
 301                         HttpStatus::header( $code );
 302                 }
 303         }
 304
 305         /**
 306          * Print a message, if possible to STDERR.
 307          * Use this in command line mode only (see isCommandLine)
 308          *
 309          * @param string $message Failure text
 310          */
 311         private static function printError( $message ) {
 312                 // NOTE: STDERR may not be available, especially if php-cgi is used from the
 313                 // command line (bug #15602). Try to produce meaningful output anyway. Using
 314                 // echo may corrupt output to STDOUT though.
 315                 if ( defined( 'STDERR' ) ) {
 316                         fwrite( STDERR, $message );
 317                 } else {
 318                         echo $message;
 319                 }
 320         }
 321
 322         /**
 323          * @param Exception $e
 324          */
 325         private static function reportOutageHTML( Exception $e ) {
 326                 global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;
 327
 328                 $sorry = htmlspecialchars( self::msg(
 329                         'dberr-problems',
 330                         'Sorry! This site is experiencing technical difficulties.'
 331                 ) );
 332                 $again = htmlspecialchars( self::msg(
 333                         'dberr-again',
 334                         'Try waiting a few minutes and reloading.'
 335                 ) );
 336
 337                 if ( $wgShowHostnames || $wgShowSQLErrors ) {
 338                         $info = str_replace(
 339                                 '$1',
 340                                 Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
 341                                 htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
 342                         );
 343                 } else {
 344                         $info = htmlspecialchars( self::msg(
 345                                 'dberr-info-hidden',
 346                                 '(Cannot access the database)'
 347                         ) );
 348                 }
 349
 350                 MessageCache::singleton()->disable(); // no DB access
 351
 352                 $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
 353
 354                 if ( $wgShowDBErrorBacktrace ) {
 355                         $html .= '<p>Backtrace:</p><pre>' .
 356                                 htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
 357                 }
 358
 359                 $html .= '<hr />';
 360                 $html .= self::googleSearchForm();
 361
 362                 echo $html;
 363         }
 364
 365         /**
 366          * @return string
 367          */
 368         private static function googleSearchForm() {
 369                 global $wgSitename, $wgCanonicalServer, $wgRequest;
 370
 371                 $usegoogle = htmlspecialchars( self::msg(
 372                         'dberr-usegoogle',
 373                         'You can try searching via Google in the meantime.'
 374                 ) );
 375                 $outofdate = htmlspecialchars( self::msg(
 376                         'dberr-outofdate',
 377                         'Note that their indexes of our content may be out of date.'
 378                 ) );
 379                 $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
 380                 $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
 381                 $server = htmlspecialchars( $wgCanonicalServer );
 382                 $sitename = htmlspecialchars( $wgSitename );
 383                 $trygoogle = <<<EOT
 384 <div style="margin: 1.5em">$usegoogle<br />
 385 <small>$outofdate</small>
 386 </div>
 387 <form method="get" action="//www.google.com/search" id="googlesearch">
 388         <input type="hidden" name="domains" value="$server" />
 389         <input type="hidden" name="num" value="50" />
 390         <input type="hidden" name="ie" value="UTF-8" />
 391         <input type="hidden" name="oe" value="UTF-8" />
 392         <input type="text" name="q" size="31" maxlength="255" value="$search" />
 393         <input type="submit" name="btnG" value="$googlesearch" />
 394         <p>
 395                 <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
 396                 <label><input type="radio" name="sitesearch" value="" />WWW</label>
 397         </p>
 398 </form>
 399 EOT;
 400                 return $trygoogle;
 401         }
 402 }