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[mediawiki.git] / includes / exception / MWExceptionRenderer.php

<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @author Aaron Schulz
 */

/**
 * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
 * @since 1.28
 */
class MWExceptionRenderer {
        const AS_RAW = 1; // show as text
        const AS_PRETTY = 2; // show as HTML

        /**
         * @param Exception|Throwable $e Original exception
         * @param integer $mode MWExceptionExposer::AS_* constant
         * @param Exception|Throwable|null $eNew New exception from attempting to show the first
         */
        public static function output( $e, $mode, $eNew = null ) {
                global $wgMimeType;

                if ( defined( 'MW_API' ) ) {
                        // Unhandled API exception, we can't be sure that format printer is alive
                        self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
                        wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
                } elseif ( self::isCommandLine() ) {
                        self::printError( self::getText( $e ) );
                } elseif ( $mode === self::AS_PRETTY ) {
                        if ( $e instanceof DBConnectionError ) {
                                self::reportOutageHTML( $e );
                        } else {
                                self::statusHeader( 500 );
                                self::header( "Content-Type: $wgMimeType; charset=utf-8" );
                                self::reportHTML( $e );
                        }
                } else {
                        if ( $eNew ) {
                                $message = "MediaWiki internal error.\n\n";
                                if ( self::showBackTrace( $e ) ) {
                                        $message .= 'Original exception: ' .
                                                MWExceptionHandler::getLogMessage( $e ) .
                                                "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
                                                "\n\nException caught inside exception handler: " .
                                                        MWExceptionHandler::getLogMessage( $eNew ) .
                                                "\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
                                } else {
                                        $message .= 'Original exception: ' .
                                                MWExceptionHandler::getPublicLogMessage( $e );
                                        $message .= "\n\nException caught inside exception handler.\n\n" .
                                                self::getShowBacktraceError( $e );
                                }
                                $message .= "\n";
                        } else {
                                if ( self::showBackTrace( $e ) ) {
                                        $message = MWExceptionHandler::getLogMessage( $e ) .
                                                "\nBacktrace:\n" .
                                                MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
                                } else {
                                        $message = MWExceptionHandler::getPublicLogMessage( $e );
                                }
                        }
                        echo nl2br( htmlspecialchars( $message ) ) . "\n";
                }
        }

        /**
         * Run hook to allow extensions to modify the text of the exception
         *
         * Called by MWException for b/c
         *
         * @param Exception|Throwable $e
         * @param string $name Class name of the exception
         * @param array $args Arguments to pass to the callback functions
         * @return string|null String to output or null if any hook has been called
         */
        public static function runHooks( $e, $name, $args = [] ) {
                global $wgExceptionHooks;

                if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
                        return null; // Just silently ignore
                }

                if ( !array_key_exists( $name, $wgExceptionHooks ) ||
                        !is_array( $wgExceptionHooks[$name] )
                ) {
                        return null;
                }

                $hooks = $wgExceptionHooks[$name];
                $callargs = array_merge( [ $e ], $args );

                foreach ( $hooks as $hook ) {
                        if (
                                is_string( $hook ) ||
                                ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
                        ) {
                                // 'function' or [ 'class', 'hook' ]
                                $result = call_user_func_array( $hook, $callargs );
                        } else {
                                $result = null;
                        }

                        if ( is_string( $result ) ) {
                                return $result;
                        }
                }

                return null;
        }

        /**
         * @param Exception|Throwable $e
         * @return bool Should the exception use $wgOut to output the error?
         */
        private static function useOutputPage( $e ) {
                // Can the extension use the Message class/wfMessage to get i18n-ed messages?
                foreach ( $e->getTrace() as $frame ) {
                        if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
                                return false;
                        }
                }

                return (
                        !empty( $GLOBALS['wgFullyInitialised'] ) &&
                        !empty( $GLOBALS['wgOut'] ) &&
                        !defined( 'MEDIAWIKI_INSTALL' )
                );
        }

        /**
         * Output the exception report using HTML
         *
         * @param Exception|Throwable $e
         */
        private static function reportHTML( $e ) {
                global $wgOut, $wgSitename;

                if ( self::useOutputPage( $e ) ) {
                        if ( $e instanceof MWException ) {
                                $wgOut->prepareErrorPage( $e->getPageTitle() );
                        } elseif ( $e instanceof DBReadOnlyError ) {
                                $wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
                        } elseif ( $e instanceof DBExpectedError ) {
                                $wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
                        } else {
                                $wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
                        }

                        $hookResult = self::runHooks( $e, get_class( $e ) );
                        if ( $hookResult ) {
                                $wgOut->addHTML( $hookResult );
                        } else {
                                // Show any custom GUI message before the details
                                if ( $e instanceof MessageSpecifier ) {
                                        $wgOut->addHTML( Message::newFromSpecifier( $e )->escaped() );
                                }
                                $wgOut->addHTML( self::getHTML( $e ) );
                        }

                        $wgOut->output();
                } else {
                        self::header( 'Content-Type: text/html; charset=utf-8' );
                        $pageTitle = self::msg( 'internalerror', 'Internal error' );
                        echo "<!DOCTYPE html>\n" .
                                '<html><head>' .
                                // Mimick OutputPage::setPageTitle behaviour
                                '<title>' .
                                htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
                                '</title>' .
                                '<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
                                "</head><body>\n";

                        $hookResult = self::runHooks( $e, get_class( $e ) . 'Raw' );
                        if ( $hookResult ) {
                                echo $hookResult;
                        } else {
                                echo self::getHTML( $e );
                        }

                        echo "</body></html>\n";
                }
        }

        /**
         * If $wgShowExceptionDetails is true, return a HTML message with a
         * backtrace to the error, otherwise show a message to ask to set it to true
         * to show that information.
         *
         * @param Exception|Throwable $e
         * @return string Html to output
         */
        public static function getHTML( $e ) {
                if ( self::showBackTrace( $e ) ) {
                        $html = "<div class=\"errorbox mw-content-ltr\"><p>" .
                                nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
                                '</p><p>Backtrace:</p><p>' .
                                nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
                                "</p></div>\n";
                } else {
                        $logId = WebRequest::getRequestId();
                        $html = "<div class=\"errorbox mw-content-ltr\">" .
                                '[' . $logId . '] ' .
                                gmdate( 'Y-m-d H:i:s' ) . ": " .
                                self::msg( "internalerror-fatal-exception",
                                        "Fatal exception of type $1",
                                        get_class( $e ),
                                        $logId,
                                        MWExceptionHandler::getURL()
                                ) . "</div>\n" .
                                "<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
                }

                return $html;
        }

        /**
         * Get a message from i18n
         *
         * @param string $key Message name
         * @param string $fallback Default message if the message cache can't be
         *                  called by the exception
         * The function also has other parameters that are arguments for the message
         * @return string Message with arguments replaced
         */
        private static function msg( $key, $fallback /*[, params...] */ ) {
                $args = array_slice( func_get_args(), 2 );
                try {
                        return wfMessage( $key, $args )->text();
                } catch ( Exception $e ) {
                        return wfMsgReplaceArgs( $fallback, $args );
                }
        }

        /**
         * @param Exception|Throwable $e
         * @return string
         */
        private static function getText( $e ) {
                if ( self::showBackTrace( $e ) ) {
                        return MWExceptionHandler::getLogMessage( $e ) .
                                "\nBacktrace:\n" .
                                MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
                } else {
                        return self::getShowBacktraceError( $e );
                }
        }

        /**
         * @param Exception|Throwable $e
         * @return bool
         */
        private static function showBackTrace( $e ) {
                global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;

                return (
                        $wgShowExceptionDetails &&
                        ( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
                );
        }

        /**
         * @param Exception|Throwable $e
         * @return string
         */
        private static function getShowBacktraceError( $e ) {
                global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
                $vars = [];
                if ( !$wgShowExceptionDetails ) {
                        $vars[] = '$wgShowExceptionDetails = true;';
                }
                if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
                        $vars[] = '$wgShowDBErrorBacktrace = true;';
                }
                $vars = implode( ' and ', $vars );
                return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information";
        }

        /**
         * @return bool
         */
        private static function isCommandLine() {
                return !empty( $GLOBALS['wgCommandLineMode'] );
        }

        /**
         * @param string $header
         */
        private static function header( $header ) {
                if ( !headers_sent() ) {
                        header( $header );
                }
        }

        /**
         * @param integer $code
         */
        private static function statusHeader( $code ) {
                if ( !headers_sent() ) {
                        HttpStatus::header( $code );
                }
        }

        /**
         * Print a message, if possible to STDERR.
         * Use this in command line mode only (see isCommandLine)
         *
         * @param string $message Failure text
         */
        private static function printError( $message ) {
                // NOTE: STDERR may not be available, especially if php-cgi is used from the
                // command line (bug #15602). Try to produce meaningful output anyway. Using
                // echo may corrupt output to STDOUT though.
                if ( defined( 'STDERR' ) ) {
                        fwrite( STDERR, $message );
                } else {
                        echo $message;
                }
        }

        /**
         * @param Exception|Throwable $e
         */
        private static function reportOutageHTML( $e ) {
                global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;

                $sorry = htmlspecialchars( self::msg(
                        'dberr-problems',
                        'Sorry! This site is experiencing technical difficulties.'
                ) );
                $again = htmlspecialchars( self::msg(
                        'dberr-again',
                        'Try waiting a few minutes and reloading.'
                ) );

                if ( $wgShowHostnames || $wgShowSQLErrors ) {
                        $info = str_replace(
                                '$1',
                                Html::element( 'span', [ 'dir' => 'ltr' ], htmlspecialchars( $e->getMessage() ) ),
                                htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
                        );
                } else {
                        $info = htmlspecialchars( self::msg(
                                'dberr-info-hidden',
                                '(Cannot access the database)'
                        ) );
                }

                MessageCache::singleton()->disable(); // no DB access

                $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";

                if ( $wgShowDBErrorBacktrace ) {
                        $html .= '<p>Backtrace:</p><pre>' .
                                htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
                }

                $html .= '<hr />';
                $html .= self::googleSearchForm();

                echo $html;
        }

        /**
         * @return string
         */
        private static function googleSearchForm() {
                global $wgSitename, $wgCanonicalServer, $wgRequest;

                $usegoogle = htmlspecialchars( self::msg(
                        'dberr-usegoogle',
                        'You can try searching via Google in the meantime.'
                ) );
                $outofdate = htmlspecialchars( self::msg(
                        'dberr-outofdate',
                        'Note that their indexes of our content may be out of date.'
                ) );
                $googlesearch = htmlspecialchars( self::msg( 'searchbutton', 'Search' ) );
                $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );
                $server = htmlspecialchars( $wgCanonicalServer );
                $sitename = htmlspecialchars( $wgSitename );
                $trygoogle = <<<EOT
<div style="margin: 1.5em">$usegoogle<br />
<small>$outofdate</small>
</div>
<form method="get" action="//www.google.com/search" id="googlesearch">
        <input type="hidden" name="domains" value="$server" />
        <input type="hidden" name="num" value="50" />
        <input type="hidden" name="ie" value="UTF-8" />
        <input type="hidden" name="oe" value="UTF-8" />
        <input type="text" name="q" size="31" maxlength="255" value="$search" />
        <input type="submit" name="btnG" value="$googlesearch" />
        <p>
                <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
                <label><input type="radio" name="sitesearch" value="" />WWW</label>
        </p>
</form>
EOT;
                return $trygoogle;
        }
}