Merge "Special:Upload should not crash on failing previews"

[mediawiki.git] / includes / WebRequest.php

<?php
/**
 * Deal with importing all those nasty globals and things
 *
 * Copyright © 2003 Brion Vibber <brion@pobox.com>
 * https://www.mediawiki.org/
 *
 * 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
 */

use MediaWiki\MediaWikiServices;
use MediaWiki\Session\Session;
use MediaWiki\Session\SessionId;
use MediaWiki\Session\SessionManager;

/**
 * The WebRequest class encapsulates getting at data passed in the
 * URL or via a POSTed form stripping illegal input characters and
 * normalizing Unicode sequences.
 *
 * @ingroup HTTP
 */
class WebRequest {
        protected $data, $headers = [];

        /**
         * Flag to make WebRequest::getHeader return an array of values.
         * @since 1.26
         */
        const GETHEADER_LIST = 1;

        /**
         * The unique request ID.
         * @var string
         */
        private static $reqId;

        /**
         * Lazy-init response object
         * @var WebResponse
         */
        private $response;

        /**
         * Cached client IP address
         * @var string
         */
        private $ip;

        /**
         * The timestamp of the start of the request, with microsecond precision.
         * @var float
         */
        protected $requestTime;

        /**
         * Cached URL protocol
         * @var string
         */
        protected $protocol;

        /**
         * @var SessionId|null Session ID to use for this
         *  request. We can't save the session directly due to reference cycles not
         *  working too well (slow GC in Zend and never collected in HHVM).
         */
        protected $sessionId = null;

        /** @var bool Whether this HTTP request is "safe" (even if it is an HTTP post) */
        protected $markedAsSafe = false;

        /**
         * @codeCoverageIgnore
         */
        public function __construct() {
                $this->requestTime = isset( $_SERVER['REQUEST_TIME_FLOAT'] )
                        ? $_SERVER['REQUEST_TIME_FLOAT'] : microtime( true );

                // POST overrides GET data
                // We don't use $_REQUEST here to avoid interference from cookies...
                $this->data = $_POST + $_GET;
        }

        /**
         * Extract relevant query arguments from the http request uri's path
         * to be merged with the normal php provided query arguments.
         * Tries to use the REQUEST_URI data if available and parses it
         * according to the wiki's configuration looking for any known pattern.
         *
         * If the REQUEST_URI is not provided we'll fall back on the PATH_INFO
         * provided by the server if any and use that to set a 'title' parameter.
         *
         * @param string $want If this is not 'all', then the function
         * will return an empty array if it determines that the URL is
         * inside a rewrite path.
         *
         * @return array Any query arguments found in path matches.
         */
        public static function getPathInfo( $want = 'all' ) {
                global $wgUsePathInfo;
                // PATH_INFO is mangled due to https://bugs.php.net/bug.php?id=31892
                // And also by Apache 2.x, double slashes are converted to single slashes.
                // So we will use REQUEST_URI if possible.
                $matches = [];
                if ( !empty( $_SERVER['REQUEST_URI'] ) ) {
                        // Slurp out the path portion to examine...
                        $url = $_SERVER['REQUEST_URI'];
                        if ( !preg_match( '!^https?://!', $url ) ) {
                                $url = 'http://unused' . $url;
                        }
                        MediaWiki\suppressWarnings();
                        $a = parse_url( $url );
                        MediaWiki\restoreWarnings();
                        if ( $a ) {
                                $path = isset( $a['path'] ) ? $a['path'] : '';

                                global $wgScript;
                                if ( $path == $wgScript && $want !== 'all' ) {
                                        // Script inside a rewrite path?
                                        // Abort to keep from breaking...
                                        return $matches;
                                }

                                $router = new PathRouter;

                                // Raw PATH_INFO style
                                $router->add( "$wgScript/$1" );

                                if ( isset( $_SERVER['SCRIPT_NAME'] )
                                        && preg_match( '/\.php5?/', $_SERVER['SCRIPT_NAME'] )
                                ) {
                                        # Check for SCRIPT_NAME, we handle index.php explicitly
                                        # But we do have some other .php files such as img_auth.php
                                        # Don't let root article paths clober the parsing for them
                                        $router->add( $_SERVER['SCRIPT_NAME'] . "/$1" );
                                }

                                global $wgArticlePath;
                                if ( $wgArticlePath ) {
                                        $router->add( $wgArticlePath );
                                }

                                global $wgActionPaths;
                                if ( $wgActionPaths ) {
                                        $router->add( $wgActionPaths, [ 'action' => '$key' ] );
                                }

                                global $wgVariantArticlePath, $wgContLang;
                                if ( $wgVariantArticlePath ) {
                                        $router->add( $wgVariantArticlePath,
                                                [ 'variant' => '$2' ],
                                                [ '$2' => $wgContLang->getVariants() ]
                                        );
                                }

                                Hooks::run( 'WebRequestPathInfoRouter', [ $router ] );

                                $matches = $router->parse( $path );
                        }
                } elseif ( $wgUsePathInfo ) {
                        if ( isset( $_SERVER['ORIG_PATH_INFO'] ) && $_SERVER['ORIG_PATH_INFO'] != '' ) {
                                // Mangled PATH_INFO
                                // https://bugs.php.net/bug.php?id=31892
                                // Also reported when ini_get('cgi.fix_pathinfo')==false
                                $matches['title'] = substr( $_SERVER['ORIG_PATH_INFO'], 1 );

                        } elseif ( isset( $_SERVER['PATH_INFO'] ) && $_SERVER['PATH_INFO'] != '' ) {
                                // Regular old PATH_INFO yay
                                $matches['title'] = substr( $_SERVER['PATH_INFO'], 1 );
                        }
                }

                return $matches;
        }

        /**
         * Work out an appropriate URL prefix containing scheme and host, based on
         * information detected from $_SERVER
         *
         * @return string
         */
        public static function detectServer() {
                global $wgAssumeProxiesUseDefaultProtocolPorts;

                $proto = self::detectProtocol();
                $stdPort = $proto === 'https' ? 443 : 80;

                $varNames = [ 'HTTP_HOST', 'SERVER_NAME', 'HOSTNAME', 'SERVER_ADDR' ];
                $host = 'localhost';
                $port = $stdPort;
                foreach ( $varNames as $varName ) {
                        if ( !isset( $_SERVER[$varName] ) ) {
                                continue;
                        }

                        $parts = IP::splitHostAndPort( $_SERVER[$varName] );
                        if ( !$parts ) {
                                // Invalid, do not use
                                continue;
                        }

                        $host = $parts[0];
                        if ( $wgAssumeProxiesUseDefaultProtocolPorts && isset( $_SERVER['HTTP_X_FORWARDED_PROTO'] ) ) {
                                // Bug 70021: Assume that upstream proxy is running on the default
                                // port based on the protocol. We have no reliable way to determine
                                // the actual port in use upstream.
                                $port = $stdPort;
                        } elseif ( $parts[1] === false ) {
                                if ( isset( $_SERVER['SERVER_PORT'] ) ) {
                                        $port = $_SERVER['SERVER_PORT'];
                                } // else leave it as $stdPort
                        } else {
                                $port = $parts[1];
                        }
                        break;
                }

                return $proto . '://' . IP::combineHostAndPort( $host, $port, $stdPort );
        }

        /**
         * Detect the protocol from $_SERVER.
         * This is for use prior to Setup.php, when no WebRequest object is available.
         * At other times, use the non-static function getProtocol().
         *
         * @return string
         */
        public static function detectProtocol() {
                if ( ( !empty( $_SERVER['HTTPS'] ) && $_SERVER['HTTPS'] !== 'off' ) ||
                        ( isset( $_SERVER['HTTP_X_FORWARDED_PROTO'] ) &&
                        $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https' ) ) {
                        return 'https';
                } else {
                        return 'http';
                }
        }

        /**
         * Get the number of seconds to have elapsed since request start,
         * in fractional seconds, with microsecond resolution.
         *
         * @return float
         * @since 1.25
         */
        public function getElapsedTime() {
                return microtime( true ) - $this->requestTime;
        }

        /**
         * Get the unique request ID.
         * This is either the value of the UNIQUE_ID envvar (if present) or a
         * randomly-generated 24-character string.
         *
         * @return string
         * @since 1.27
         */
        public static function getRequestId() {
                if ( !self::$reqId ) {
                        self::$reqId = isset( $_SERVER['UNIQUE_ID'] )
                                ? $_SERVER['UNIQUE_ID'] : wfRandomString( 24 );
                }

                return self::$reqId;
        }

        /**
         * Override the unique request ID. This is for sub-requests, such as jobs,
         * that wish to use the same id but are not part of the same execution context.
         *
         * @param string $id
         * @since 1.27
         */
        public static function overrideRequestId( $id ) {
                self::$reqId = $id;
        }

        /**
         * Get the current URL protocol (http or https)
         * @return string
         */
        public function getProtocol() {
                if ( $this->protocol === null ) {
                        $this->protocol = self::detectProtocol();
                }
                return $this->protocol;
        }

        /**
         * Check for title, action, and/or variant data in the URL
         * and interpolate it into the GET variables.
         * This should only be run after $wgContLang is available,
         * as we may need the list of language variants to determine
         * available variant URLs.
         */
        public function interpolateTitle() {
                // bug 16019: title interpolation on API queries is useless and sometimes harmful
                if ( defined( 'MW_API' ) ) {
                        return;
                }

                $matches = self::getPathInfo( 'title' );
                foreach ( $matches as $key => $val ) {
                        $this->data[$key] = $_GET[$key] = $_REQUEST[$key] = $val;
                }
        }

        /**
         * URL rewriting function; tries to extract page title and,
         * optionally, one other fixed parameter value from a URL path.
         *
         * @param string $path The URL path given from the client
         * @param array $bases One or more URLs, optionally with $1 at the end
         * @param string|bool $key If provided, the matching key in $bases will be
         *    passed on as the value of this URL parameter
         * @return array Array of URL variables to interpolate; empty if no match
         */
        static function extractTitle( $path, $bases, $key = false ) {
                foreach ( (array)$bases as $keyValue => $base ) {
                        // Find the part after $wgArticlePath
                        $base = str_replace( '$1', '', $base );
                        $baseLen = strlen( $base );
                        if ( substr( $path, 0, $baseLen ) == $base ) {
                                $raw = substr( $path, $baseLen );
                                if ( $raw !== '' ) {
                                        $matches = [ 'title' => rawurldecode( $raw ) ];
                                        if ( $key ) {
                                                $matches[$key] = $keyValue;
                                        }
                                        return $matches;
                                }
                        }
                }
                return [];
        }

        /**
         * Recursively normalizes UTF-8 strings in the given array.
         *
         * @param string|array $data
         * @return array|string Cleaned-up version of the given
         * @private
         */
        public function normalizeUnicode( $data ) {
                if ( is_array( $data ) ) {
                        foreach ( $data as $key => $val ) {
                                $data[$key] = $this->normalizeUnicode( $val );
                        }
                } else {
                        global $wgContLang;
                        $data = isset( $wgContLang ) ?
                                $wgContLang->normalize( $data ) :
                                UtfNormal\Validator::cleanUp( $data );
                }
                return $data;
        }

        /**
         * Fetch a value from the given array or return $default if it's not set.
         *
         * @param array $arr
         * @param string $name
         * @param mixed $default
         * @return mixed
         */
        private function getGPCVal( $arr, $name, $default ) {
                # PHP is so nice to not touch input data, except sometimes:
                # https://secure.php.net/variables.external#language.variables.external.dot-in-names
                # Work around PHP *feature* to avoid *bugs* elsewhere.
                $name = strtr( $name, '.', '_' );
                if ( isset( $arr[$name] ) ) {
                        global $wgContLang;
                        $data = $arr[$name];
                        if ( isset( $_GET[$name] ) && !is_array( $data ) ) {
                                # Check for alternate/legacy character encoding.
                                if ( isset( $wgContLang ) ) {
                                        $data = $wgContLang->checkTitleEncoding( $data );
                                }
                        }
                        $data = $this->normalizeUnicode( $data );
                        return $data;
                } else {
                        return $default;
                }
        }

        /**
         * Fetch a scalar from the input without normalization, or return $default
         * if it's not set.
         *
         * Unlike self::getVal(), this does not perform any normalization on the
         * input value.
         *
         * @since 1.28
         * @param string $name
         * @param string|null $default Optional default
         * @return string
         */
        public function getRawVal( $name, $default = null ) {
                $name = strtr( $name, '.', '_' ); // See comment in self::getGPCVal()
                if ( isset( $this->data[$name] ) && !is_array( $this->data[$name] ) ) {
                        $val = $this->data[$name];
                } else {
                        $val = $default;
                }
                if ( is_null( $val ) ) {
                        return $val;
                } else {
                        return (string)$val;
                }
        }

        /**
         * Fetch a scalar from the input or return $default if it's not set.
         * Returns a string. Arrays are discarded. Useful for
         * non-freeform text inputs (e.g. predefined internal text keys
         * selected by a drop-down menu). For freeform input, see getText().
         *
         * @param string $name
         * @param string $default Optional default (or null)
         * @return string
         */
        public function getVal( $name, $default = null ) {
                $val = $this->getGPCVal( $this->data, $name, $default );
                if ( is_array( $val ) ) {
                        $val = $default;
                }
                if ( is_null( $val ) ) {
                        return $val;
                } else {
                        return (string)$val;
                }
        }

        /**
         * Set an arbitrary value into our get/post data.
         *
         * @param string $key Key name to use
         * @param mixed $value Value to set
         * @return mixed Old value if one was present, null otherwise
         */
        public function setVal( $key, $value ) {
                $ret = isset( $this->data[$key] ) ? $this->data[$key] : null;
                $this->data[$key] = $value;
                return $ret;
        }

        /**
         * Unset an arbitrary value from our get/post data.
         *
         * @param string $key Key name to use
         * @return mixed Old value if one was present, null otherwise
         */
        public function unsetVal( $key ) {
                if ( !isset( $this->data[$key] ) ) {
                        $ret = null;
                } else {
                        $ret = $this->data[$key];
                        unset( $this->data[$key] );
                }
                return $ret;
        }

        /**
         * Fetch an array from the input or return $default if it's not set.
         * If source was scalar, will return an array with a single element.
         * If no source and no default, returns null.
         *
         * @param string $name
         * @param array $default Optional default (or null)
         * @return array
         */
        public function getArray( $name, $default = null ) {
                $val = $this->getGPCVal( $this->data, $name, $default );
                if ( is_null( $val ) ) {
                        return null;
                } else {
                        return (array)$val;
                }
        }

        /**
         * Fetch an array of integers, or return $default if it's not set.
         * If source was scalar, will return an array with a single element.
         * If no source and no default, returns null.
         * If an array is returned, contents are guaranteed to be integers.
         *
         * @param string $name
         * @param array $default Option default (or null)
         * @return array Array of ints
         */
        public function getIntArray( $name, $default = null ) {
                $val = $this->getArray( $name, $default );
                if ( is_array( $val ) ) {
                        $val = array_map( 'intval', $val );
                }
                return $val;
        }

        /**
         * Fetch an integer value from the input or return $default if not set.
         * Guaranteed to return an integer; non-numeric input will typically
         * return 0.
         *
         * @param string $name
         * @param int $default
         * @return int
         */
        public function getInt( $name, $default = 0 ) {
                return intval( $this->getRawVal( $name, $default ) );
        }

        /**
         * Fetch an integer value from the input or return null if empty.
         * Guaranteed to return an integer or null; non-numeric input will
         * typically return null.
         *
         * @param string $name
         * @return int|null
         */
        public function getIntOrNull( $name ) {
                $val = $this->getRawVal( $name );
                return is_numeric( $val )
                        ? intval( $val )
                        : null;
        }

        /**
         * Fetch a floating point value from the input or return $default if not set.
         * Guaranteed to return a float; non-numeric input will typically
         * return 0.
         *
         * @since 1.23
         * @param string $name
         * @param float $default
         * @return float
         */
        public function getFloat( $name, $default = 0.0 ) {
                return floatval( $this->getRawVal( $name, $default ) );
        }

        /**
         * Fetch a boolean value from the input or return $default if not set.
         * Guaranteed to return true or false, with normal PHP semantics for
         * boolean interpretation of strings.
         *
         * @param string $name
         * @param bool $default
         * @return bool
         */
        public function getBool( $name, $default = false ) {
                return (bool)$this->getRawVal( $name, $default );
        }

        /**
         * Fetch a boolean value from the input or return $default if not set.
         * Unlike getBool, the string "false" will result in boolean false, which is
         * useful when interpreting information sent from JavaScript.
         *
         * @param string $name
         * @param bool $default
         * @return bool
         */
        public function getFuzzyBool( $name, $default = false ) {
                return $this->getBool( $name, $default )
                        && strcasecmp( $this->getRawVal( $name ), 'false' ) !== 0;
        }

        /**
         * Return true if the named value is set in the input, whatever that
         * value is (even "0"). Return false if the named value is not set.
         * Example use is checking for the presence of check boxes in forms.
         *
         * @param string $name
         * @return bool
         */
        public function getCheck( $name ) {
                # Checkboxes and buttons are only present when clicked
                # Presence connotes truth, absence false
                return $this->getRawVal( $name, null ) !== null;
        }

        /**
         * Fetch a text string from the given array or return $default if it's not
         * set. Carriage returns are stripped from the text. This should generally
         * be used for form "<textarea>" and "<input>" fields, and for
         * user-supplied freeform text input.
         *
         * @param string $name
         * @param string $default Optional
         * @return string
         */
        public function getText( $name, $default = '' ) {
                $val = $this->getVal( $name, $default );
                return str_replace( "\r\n", "\n", $val );
        }

        /**
         * Extracts the given named values into an array.
         * If no arguments are given, returns all input values.
         * No transformation is performed on the values.
         *
         * @return array
         */
        public function getValues() {
                $names = func_get_args();
                if ( count( $names ) == 0 ) {
                        $names = array_keys( $this->data );
                }

                $retVal = [];
                foreach ( $names as $name ) {
                        $value = $this->getGPCVal( $this->data, $name, null );
                        if ( !is_null( $value ) ) {
                                $retVal[$name] = $value;
                        }
                }
                return $retVal;
        }

        /**
         * Returns the names of all input values excluding those in $exclude.
         *
         * @param array $exclude
         * @return array
         */
        public function getValueNames( $exclude = [] ) {
                return array_diff( array_keys( $this->getValues() ), $exclude );
        }

        /**
         * Get the values passed in the query string.
         * No transformation is performed on the values.
         *
         * @codeCoverageIgnore
         * @return array
         */
        public function getQueryValues() {
                return $_GET;
        }

        /**
         * Return the contents of the Query with no decoding. Use when you need to
         * know exactly what was sent, e.g. for an OAuth signature over the elements.
         *
         * @codeCoverageIgnore
         * @return string
         */
        public function getRawQueryString() {
                return $_SERVER['QUERY_STRING'];
        }

        /**
         * Return the contents of the POST with no decoding. Use when you need to
         * know exactly what was sent, e.g. for an OAuth signature over the elements.
         *
         * @return string
         */
        public function getRawPostString() {
                if ( !$this->wasPosted() ) {
                        return '';
                }
                return $this->getRawInput();
        }

        /**
         * Return the raw request body, with no processing. Cached since some methods
         * disallow reading the stream more than once. As stated in the php docs, this
         * does not work with enctype="multipart/form-data".
         *
         * @return string
         */
        public function getRawInput() {
                static $input = null;
                if ( $input === null ) {
                        $input = file_get_contents( 'php://input' );
                }
                return $input;
        }

        /**
         * Get the HTTP method used for this request.
         *
         * @return string
         */
        public function getMethod() {
                return isset( $_SERVER['REQUEST_METHOD'] ) ? $_SERVER['REQUEST_METHOD'] : 'GET';
        }

        /**
         * Returns true if the present request was reached by a POST operation,
         * false otherwise (GET, HEAD, or command-line).
         *
         * Note that values retrieved by the object may come from the
         * GET URL etc even on a POST request.
         *
         * @return bool
         */
        public function wasPosted() {
                return $this->getMethod() == 'POST';
        }

        /**
         * Return the session for this request
         *
         * This might unpersist an existing session if it was invalid.
         *
         * @since 1.27
         * @note For performance, keep the session locally if you will be making
         *  much use of it instead of calling this method repeatedly.
         * @return Session
         */
        public function getSession() {
                if ( $this->sessionId !== null ) {
                        $session = SessionManager::singleton()->getSessionById( (string)$this->sessionId, true, $this );
                        if ( $session ) {
                                return $session;
                        }
                }

                $session = SessionManager::singleton()->getSessionForRequest( $this );
                $this->sessionId = $session->getSessionId();
                return $session;
        }

        /**
         * Set the session for this request
         * @since 1.27
         * @private For use by MediaWiki\Session classes only
         * @param SessionId $sessionId
         */
        public function setSessionId( SessionId $sessionId ) {
                $this->sessionId = $sessionId;
        }

        /**
         * Get the session id for this request, if any
         * @since 1.27
         * @private For use by MediaWiki\Session classes only
         * @return SessionId|null
         */
        public function getSessionId() {
                return $this->sessionId;
        }

        /**
         * Get a cookie from the $_COOKIE jar
         *
         * @param string $key The name of the cookie
         * @param string $prefix A prefix to use for the cookie name, if not $wgCookiePrefix
         * @param mixed $default What to return if the value isn't found
         * @return mixed Cookie value or $default if the cookie not set
         */
        public function getCookie( $key, $prefix = null, $default = null ) {
                if ( $prefix === null ) {
                        global $wgCookiePrefix;
                        $prefix = $wgCookiePrefix;
                }
                return $this->getGPCVal( $_COOKIE, $prefix . $key, $default );
        }

        /**
         * Return the path and query string portion of the main request URI.
         * This will be suitable for use as a relative link in HTML output.
         *
         * @throws MWException
         * @return string
         */
        public static function getGlobalRequestURL() {
                if ( isset( $_SERVER['REQUEST_URI'] ) && strlen( $_SERVER['REQUEST_URI'] ) ) {
                        $base = $_SERVER['REQUEST_URI'];
                } elseif ( isset( $_SERVER['HTTP_X_ORIGINAL_URL'] )
                        && strlen( $_SERVER['HTTP_X_ORIGINAL_URL'] )
                ) {
                        // Probably IIS; doesn't set REQUEST_URI
                        $base = $_SERVER['HTTP_X_ORIGINAL_URL'];
                } elseif ( isset( $_SERVER['SCRIPT_NAME'] ) ) {
                        $base = $_SERVER['SCRIPT_NAME'];
                        if ( isset( $_SERVER['QUERY_STRING'] ) && $_SERVER['QUERY_STRING'] != '' ) {
                                $base .= '?' . $_SERVER['QUERY_STRING'];
                        }
                } else {
                        // This shouldn't happen!
                        throw new MWException( "Web server doesn't provide either " .
                                "REQUEST_URI, HTTP_X_ORIGINAL_URL or SCRIPT_NAME. Report details " .
                                "of your web server configuration to https://phabricator.wikimedia.org/" );
                }
                // User-agents should not send a fragment with the URI, but
                // if they do, and the web server passes it on to us, we
                // need to strip it or we get false-positive redirect loops
                // or weird output URLs
                $hash = strpos( $base, '#' );
                if ( $hash !== false ) {
                        $base = substr( $base, 0, $hash );
                }

                if ( $base[0] == '/' ) {
                        // More than one slash will look like it is protocol relative
                        return preg_replace( '!^/+!', '/', $base );
                } else {
                        // We may get paths with a host prepended; strip it.
                        return preg_replace( '!^[^:]+://[^/]+/+!', '/', $base );
                }
        }

        /**
         * Return the path and query string portion of the request URI.
         * This will be suitable for use as a relative link in HTML output.
         *
         * @throws MWException
         * @return string
         */
        public function getRequestURL() {
                return self::getGlobalRequestURL();
        }

        /**
         * Return the request URI with the canonical service and hostname, path,
         * and query string. This will be suitable for use as an absolute link
         * in HTML or other output.
         *
         * If $wgServer is protocol-relative, this will return a fully
         * qualified URL with the protocol that was used for this request.
         *
         * @return string
         */
        public function getFullRequestURL() {
                return wfExpandUrl( $this->getRequestURL(), PROTO_CURRENT );
        }

        /**
         * @param string $key
         * @param string $value
         * @return string
         */
        public function appendQueryValue( $key, $value ) {
                return $this->appendQueryArray( [ $key => $value ] );
        }

        /**
         * Appends or replaces value of query variables.
         *
         * @param array $array Array of values to replace/add to query
         * @return string
         */
        public function appendQueryArray( $array ) {
                $newquery = $this->getQueryValues();
                unset( $newquery['title'] );
                $newquery = array_merge( $newquery, $array );

                return wfArrayToCgi( $newquery );
        }

        /**
         * Check for limit and offset parameters on the input, and return sensible
         * defaults if not given. The limit must be positive and is capped at 5000.
         * Offset must be positive but is not capped.
         *
         * @param int $deflimit Limit to use if no input and the user hasn't set the option.
         * @param string $optionname To specify an option other than rclimit to pull from.
         * @return int[] First element is limit, second is offset
         */
        public function getLimitOffset( $deflimit = 50, $optionname = 'rclimit' ) {
                global $wgUser;

                $limit = $this->getInt( 'limit', 0 );
                if ( $limit < 0 ) {
                        $limit = 0;
                }
                if ( ( $limit == 0 ) && ( $optionname != '' ) ) {
                        $limit = $wgUser->getIntOption( $optionname );
                }
                if ( $limit <= 0 ) {
                        $limit = $deflimit;
                }
                if ( $limit > 5000 ) {
                        $limit = 5000; # We have *some* limits...
                }

                $offset = $this->getInt( 'offset', 0 );
                if ( $offset < 0 ) {
                        $offset = 0;
                }

                return [ $limit, $offset ];
        }

        /**
         * Return the path to the temporary file where PHP has stored the upload.
         *
         * @param string $key
         * @return string|null String or null if no such file.
         */
        public function getFileTempname( $key ) {
                $file = new WebRequestUpload( $this, $key );
                return $file->getTempName();
        }

        /**
         * Return the upload error or 0
         *
         * @param string $key
         * @return int
         */
        public function getUploadError( $key ) {
                $file = new WebRequestUpload( $this, $key );
                return $file->getError();
        }

        /**
         * Return the original filename of the uploaded file, as reported by
         * the submitting user agent. HTML-style character entities are
         * interpreted and normalized to Unicode normalization form C, in part
         * to deal with weird input from Safari with non-ASCII filenames.
         *
         * Other than this the name is not verified for being a safe filename.
         *
         * @param string $key
         * @return string|null String or null if no such file.
         */
        public function getFileName( $key ) {
                $file = new WebRequestUpload( $this, $key );
                return $file->getName();
        }

        /**
         * Return a WebRequestUpload object corresponding to the key
         *
         * @param string $key
         * @return WebRequestUpload
         */
        public function getUpload( $key ) {
                return new WebRequestUpload( $this, $key );
        }

        /**
         * Return a handle to WebResponse style object, for setting cookies,
         * headers and other stuff, for Request being worked on.
         *
         * @return WebResponse
         */
        public function response() {
                /* Lazy initialization of response object for this request */
                if ( !is_object( $this->response ) ) {
                        $class = ( $this instanceof FauxRequest ) ? 'FauxResponse' : 'WebResponse';
                        $this->response = new $class();
                }
                return $this->response;
        }

        /**
         * Initialise the header list
         */
        protected function initHeaders() {
                if ( count( $this->headers ) ) {
                        return;
                }

                $apacheHeaders = function_exists( 'apache_request_headers' ) ? apache_request_headers() : false;
                if ( $apacheHeaders ) {
                        foreach ( $apacheHeaders as $tempName => $tempValue ) {
                                $this->headers[strtoupper( $tempName )] = $tempValue;
                        }
                } else {
                        foreach ( $_SERVER as $name => $value ) {
                                if ( substr( $name, 0, 5 ) === 'HTTP_' ) {
                                        $name = str_replace( '_', '-', substr( $name, 5 ) );
                                        $this->headers[$name] = $value;
                                } elseif ( $name === 'CONTENT_LENGTH' ) {
                                        $this->headers['CONTENT-LENGTH'] = $value;
                                }
                        }
                }
        }

        /**
         * Get an array containing all request headers
         *
         * @return array Mapping header name to its value
         */
        public function getAllHeaders() {
                $this->initHeaders();
                return $this->headers;
        }

        /**
         * Get a request header, or false if it isn't set.
         *
         * @param string $name Case-insensitive header name
         * @param int $flags Bitwise combination of:
         *   WebRequest::GETHEADER_LIST  Treat the header as a comma-separated list
         *                               of values, as described in RFC 2616 § 4.2.
         *                               (since 1.26).
         * @return string|array|bool False if header is unset; otherwise the
         *  header value(s) as either a string (the default) or an array, if
         *  WebRequest::GETHEADER_LIST flag was set.
         */
        public function getHeader( $name, $flags = 0 ) {
                $this->initHeaders();
                $name = strtoupper( $name );
                if ( !isset( $this->headers[$name] ) ) {
                        return false;
                }
                $value = $this->headers[$name];
                if ( $flags & self::GETHEADER_LIST ) {
                        $value = array_map( 'trim', explode( ',', $value ) );
                }
                return $value;
        }

        /**
         * Get data from the session
         *
         * @note Prefer $this->getSession() instead if making multiple calls.
         * @param string $key Name of key in the session
         * @return mixed
         */
        public function getSessionData( $key ) {
                return $this->getSession()->get( $key );
        }

        /**
         * Set session data
         *
         * @note Prefer $this->getSession() instead if making multiple calls.
         * @param string $key Name of key in the session
         * @param mixed $data
         */
        public function setSessionData( $key, $data ) {
                $this->getSession()->set( $key, $data );
        }

        /**
         * Check if Internet Explorer will detect an incorrect cache extension in
         * PATH_INFO or QUERY_STRING. If the request can't be allowed, show an error
         * message or redirect to a safer URL. Returns true if the URL is OK, and
         * false if an error message has been shown and the request should be aborted.
         *
         * @param array $extWhitelist
         * @throws HttpError
         * @return bool
         */
        public function checkUrlExtension( $extWhitelist = [] ) {
                $extWhitelist[] = 'php';
                if ( IEUrlExtension::areServerVarsBad( $_SERVER, $extWhitelist ) ) {
                        if ( !$this->wasPosted() ) {
                                $newUrl = IEUrlExtension::fixUrlForIE6(
                                        $this->getFullRequestURL(), $extWhitelist );
                                if ( $newUrl !== false ) {
                                        $this->doSecurityRedirect( $newUrl );
                                        return false;
                                }
                        }
                        throw new HttpError( 403,
                                'Invalid file extension found in the path info or query string.' );
                }
                return true;
        }

        /**
         * Attempt to redirect to a URL with a QUERY_STRING that's not dangerous in
         * IE 6. Returns true if it was successful, false otherwise.
         *
         * @param string $url
         * @return bool
         */
        protected function doSecurityRedirect( $url ) {
                header( 'Location: ' . $url );
                header( 'Content-Type: text/html' );
                $encUrl = htmlspecialchars( $url );
                echo <<<HTML
<!DOCTYPE html>
<html>
<head>
<title>Security redirect</title>
</head>
<body>
<h1>Security redirect</h1>
<p>
We can't serve non-HTML content from the URL you have requested, because
Internet Explorer would interpret it as an incorrect and potentially dangerous
content type.</p>
<p>Instead, please use <a href="$encUrl">this URL</a>, which is the same as the
URL you have requested, except that "&amp;*" is appended. This prevents Internet
Explorer from seeing a bogus file extension.
</p>
</body>
</html>
HTML;
                echo "\n";
                return true;
        }

        /**
         * Parse the Accept-Language header sent by the client into an array
         *
         * @return array Array( languageCode => q-value ) sorted by q-value in
         *   descending order then appearing time in the header in ascending order.
         * May contain the "language" '*', which applies to languages other than those explicitly listed.
         * This is aligned with rfc2616 section 14.4
         * Preference for earlier languages appears in rfc3282 as an extension to HTTP/1.1.
         */
        public function getAcceptLang() {
                // Modified version of code found at
                // http://www.thefutureoftheweb.com/blog/use-accept-language-header
                $acceptLang = $this->getHeader( 'Accept-Language' );
                if ( !$acceptLang ) {
                        return [];
                }

                // Return the language codes in lower case
                $acceptLang = strtolower( $acceptLang );

                // Break up string into pieces (languages and q factors)
                $lang_parse = null;
                preg_match_all(
                        '/([a-z]{1,8}(-[a-z]{1,8})*|\*)\s*(;\s*q\s*=\s*(1(\.0{0,3})?|0(\.[0-9]{0,3})?)?)?/',
                        $acceptLang,
                        $lang_parse
                );

                if ( !count( $lang_parse[1] ) ) {
                        return [];
                }

                $langcodes = $lang_parse[1];
                $qvalues = $lang_parse[4];
                $indices = range( 0, count( $lang_parse[1] ) - 1 );

                // Set default q factor to 1
                foreach ( $indices as $index ) {
                        if ( $qvalues[$index] === '' ) {
                                $qvalues[$index] = 1;
                        } elseif ( $qvalues[$index] == 0 ) {
                                unset( $langcodes[$index], $qvalues[$index], $indices[$index] );
                        }
                }

                // Sort list. First by $qvalues, then by order. Reorder $langcodes the same way
                array_multisort( $qvalues, SORT_DESC, SORT_NUMERIC, $indices, $langcodes );

                // Create a list like "en" => 0.8
                $langs = array_combine( $langcodes, $qvalues );

                return $langs;
        }

        /**
         * Fetch the raw IP from the request
         *
         * @since 1.19
         *
         * @throws MWException
         * @return string
         */
        protected function getRawIP() {
                if ( !isset( $_SERVER['REMOTE_ADDR'] ) ) {
                        return null;
                }

                if ( is_array( $_SERVER['REMOTE_ADDR'] ) || strpos( $_SERVER['REMOTE_ADDR'], ',' ) !== false ) {
                        throw new MWException( __METHOD__
                                . " : Could not determine the remote IP address due to multiple values." );
                } else {
                        $ipchain = $_SERVER['REMOTE_ADDR'];
                }

                return IP::canonicalize( $ipchain );
        }

        /**
         * Work out the IP address based on various globals
         * For trusted proxies, use the XFF client IP (first of the chain)
         *
         * @since 1.19
         *
         * @throws MWException
         * @return string
         */
        public function getIP() {
                global $wgUsePrivateIPs;

                # Return cached result
                if ( $this->ip !== null ) {
                        return $this->ip;
                }

                # collect the originating ips
                $ip = $this->getRawIP();
                if ( !$ip ) {
                        throw new MWException( 'Unable to determine IP.' );
                }

                # Append XFF
                $forwardedFor = $this->getHeader( 'X-Forwarded-For' );
                if ( $forwardedFor !== false ) {
                        $proxyLookup = MediaWikiServices::getInstance()->getProxyLookup();
                        $isConfigured = $proxyLookup->isConfiguredProxy( $ip );
                        $ipchain = array_map( 'trim', explode( ',', $forwardedFor ) );
                        $ipchain = array_reverse( $ipchain );
                        array_unshift( $ipchain, $ip );

                        # Step through XFF list and find the last address in the list which is a
                        # trusted server. Set $ip to the IP address given by that trusted server,
                        # unless the address is not sensible (e.g. private). However, prefer private
                        # IP addresses over proxy servers controlled by this site (more sensible).
                        # Note that some XFF values might be "unknown" with Squid/Varnish.
                        foreach ( $ipchain as $i => $curIP ) {
                                $curIP = IP::sanitizeIP( IP::canonicalize( $curIP ) );
                                if ( !$curIP || !isset( $ipchain[$i + 1] ) || $ipchain[$i + 1] === 'unknown'
                                        || !$proxyLookup->isTrustedProxy( $curIP )
                                ) {
                                        break; // IP is not valid/trusted or does not point to anything
                                }
                                if (
                                        IP::isPublic( $ipchain[$i + 1] ) ||
                                        $wgUsePrivateIPs ||
                                        $proxyLookup->isConfiguredProxy( $curIP ) // bug 48919; treat IP as sane
                                ) {
                                        // Follow the next IP according to the proxy
                                        $nextIP = IP::canonicalize( $ipchain[$i + 1] );
                                        if ( !$nextIP && $isConfigured ) {
                                                // We have not yet made it past CDN/proxy servers of this site,
                                                // so either they are misconfigured or there is some IP spoofing.
                                                throw new MWException( "Invalid IP given in XFF '$forwardedFor'." );
                                        }
                                        $ip = $nextIP;
                                        // keep traversing the chain
                                        continue;
                                }
                                break;
                        }
                }

                # Allow extensions to improve our guess
                Hooks::run( 'GetIP', [ &$ip ] );

                if ( !$ip ) {
                        throw new MWException( "Unable to determine IP." );
                }

                wfDebug( "IP: $ip\n" );
                $this->ip = $ip;
                return $ip;
        }

        /**
         * @param string $ip
         * @return void
         * @since 1.21
         */
        public function setIP( $ip ) {
                $this->ip = $ip;
        }

        /**
         * Check if this request uses a "safe" HTTP method
         *
         * Safe methods are verbs (e.g. GET/HEAD/OPTIONS) used for obtaining content. Such requests
         * are not expected to mutate content, especially in ways attributable to the client. Verbs
         * like POST and PUT are typical of non-safe requests which often change content.
         *
         * @return bool
         * @see https://tools.ietf.org/html/rfc7231#section-4.2.1
         * @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
         * @since 1.28
         */
        public function hasSafeMethod() {
                if ( !isset( $_SERVER['REQUEST_METHOD'] ) ) {
                        return false; // CLI mode
                }

                return in_array( $_SERVER['REQUEST_METHOD'], [ 'GET', 'HEAD', 'OPTIONS', 'TRACE' ] );
        }

        /**
         * Whether this request should be identified as being "safe"
         *
         * This means that the client is not requesting any state changes and that database writes
         * are not inherently required. Ideally, no visible updates would happen at all. If they
         * must, then they should not be publically attributed to the end user.
         *
         * In more detail:
         *   - Cache populations and refreshes MAY occur.
         *   - Private user session updates and private server logging MAY occur.
         *   - Updates to private viewing activity data MAY occur via DeferredUpdates.
         *   - Other updates SHOULD NOT occur (e.g. modifying content assets).
         *
         * @return bool
         * @see https://tools.ietf.org/html/rfc7231#section-4.2.1
         * @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
         * @since 1.28
         */
        public function isSafeRequest() {
                if ( $this->markedAsSafe && $this->wasPosted() ) {
                        return true; // marked as a "safe" POST
                }

                return $this->hasSafeMethod();
        }

        /**
         * Mark this request as identified as being nullipotent even if it is a POST request
         *
         * POST requests are often used due to the need for a client payload, even if the request
         * is otherwise equivalent to a "safe method" request.
         *
         * @see https://tools.ietf.org/html/rfc7231#section-4.2.1
         * @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
         * @since 1.28
         */
        public function markAsSafeRequest() {
                $this->markedAsSafe = true;
        }
}