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