Move ILoadBalancer to Rdbms namespace

[mediawiki.git] / includes / Block.php

<?php
/**
 * Blocks and bans object
 *
 * 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;

class Block {
        /** @var string */
        public $mReason;

        /** @var string */
        public $mTimestamp;

        /** @var bool */
        public $mAuto;

        /** @var string */
        public $mExpiry;

        /** @var bool */
        public $mHideName;

        /** @var int */
        public $mParentBlockId;

        /** @var int */
        protected $mId;

        /** @var bool */
        protected $mFromMaster;

        /** @var bool */
        protected $mBlockEmail;

        /** @var bool */
        protected $mDisableUsertalk;

        /** @var bool */
        protected $mCreateAccount;

        /** @var User|string */
        protected $target;

        /** @var int Hack for foreign blocking (CentralAuth) */
        protected $forcedTargetID;

        /** @var int Block::TYPE_ constant. Can only be USER, IP or RANGE internally */
        protected $type;

        /** @var User */
        protected $blocker;

        /** @var bool */
        protected $isHardblock;

        /** @var bool */
        protected $isAutoblocking;

        /** @var string|null */
        protected $systemBlockType;

        # TYPE constants
        const TYPE_USER = 1;
        const TYPE_IP = 2;
        const TYPE_RANGE = 3;
        const TYPE_AUTO = 4;
        const TYPE_ID = 5;

        /**
         * Create a new block with specified parameters on a user, IP or IP range.
         *
         * @param array $options Parameters of the block:
         *     address string|User  Target user name, User object, IP address or IP range
         *     user int             Override target user ID (for foreign users)
         *     by int               User ID of the blocker
         *     reason string        Reason of the block
         *     timestamp string     The time at which the block comes into effect
         *     auto bool            Is this an automatic block?
         *     expiry string        Timestamp of expiration of the block or 'infinity'
         *     anonOnly bool        Only disallow anonymous actions
         *     createAccount bool   Disallow creation of new accounts
         *     enableAutoblock bool Enable automatic blocking
         *     hideName bool        Hide the target user name
         *     blockEmail bool      Disallow sending emails
         *     allowUsertalk bool   Allow the target to edit its own talk page
         *     byText string        Username of the blocker (for foreign users)
         *     systemBlock string   Indicate that this block is automatically
         *                          created by MediaWiki rather than being stored
         *                          in the database. Value is a string to return
         *                          from self::getSystemBlockType().
         *
         * @since 1.26 accepts $options array instead of individual parameters; order
         * of parameters above reflects the original order
         */
        function __construct( $options = [] ) {
                $defaults = [
                        'address'         => '',
                        'user'            => null,
                        'by'              => null,
                        'reason'          => '',
                        'timestamp'       => '',
                        'auto'            => false,
                        'expiry'          => '',
                        'anonOnly'        => false,
                        'createAccount'   => false,
                        'enableAutoblock' => false,
                        'hideName'        => false,
                        'blockEmail'      => false,
                        'allowUsertalk'   => false,
                        'byText'          => '',
                        'systemBlock'     => null,
                ];

                if ( func_num_args() > 1 || !is_array( $options ) ) {
                        $options = array_combine(
                                array_slice( array_keys( $defaults ), 0, func_num_args() ),
                                func_get_args()
                        );
                        wfDeprecated( __METHOD__ . ' with multiple arguments', '1.26' );
                }

                $options += $defaults;

                $this->setTarget( $options['address'] );

                if ( $this->target instanceof User && $options['user'] ) {
                        # Needed for foreign users
                        $this->forcedTargetID = $options['user'];
                }

                if ( $options['by'] ) {
                        # Local user
                        $this->setBlocker( User::newFromId( $options['by'] ) );
                } else {
                        # Foreign user
                        $this->setBlocker( $options['byText'] );
                }

                $this->mReason = $options['reason'];
                $this->mTimestamp = wfTimestamp( TS_MW, $options['timestamp'] );
                $this->mExpiry = wfGetDB( DB_REPLICA )->decodeExpiry( $options['expiry'] );

                # Boolean settings
                $this->mAuto = (bool)$options['auto'];
                $this->mHideName = (bool)$options['hideName'];
                $this->isHardblock( !$options['anonOnly'] );
                $this->isAutoblocking( (bool)$options['enableAutoblock'] );

                # Prevention measures
                $this->prevents( 'sendemail', (bool)$options['blockEmail'] );
                $this->prevents( 'editownusertalk', !$options['allowUsertalk'] );
                $this->prevents( 'createaccount', (bool)$options['createAccount'] );

                $this->mFromMaster = false;
                $this->systemBlockType = $options['systemBlock'];
        }

        /**
         * Load a blocked user from their block id.
         *
         * @param int $id Block id to search for
         * @return Block|null
         */
        public static function newFromID( $id ) {
                $dbr = wfGetDB( DB_REPLICA );
                $res = $dbr->selectRow(
                        'ipblocks',
                        self::selectFields(),
                        [ 'ipb_id' => $id ],
                        __METHOD__
                );
                if ( $res ) {
                        return self::newFromRow( $res );
                } else {
                        return null;
                }
        }

        /**
         * Return the list of ipblocks fields that should be selected to create
         * a new block.
         * @return array
         */
        public static function selectFields() {
                return [
                        'ipb_id',
                        'ipb_address',
                        'ipb_by',
                        'ipb_by_text',
                        'ipb_reason',
                        'ipb_timestamp',
                        'ipb_auto',
                        'ipb_anon_only',
                        'ipb_create_account',
                        'ipb_enable_autoblock',
                        'ipb_expiry',
                        'ipb_deleted',
                        'ipb_block_email',
                        'ipb_allow_usertalk',
                        'ipb_parent_block_id',
                ];
        }

        /**
         * Check if two blocks are effectively equal.  Doesn't check irrelevant things like
         * the blocking user or the block timestamp, only things which affect the blocked user
         *
         * @param Block $block
         *
         * @return bool
         */
        public function equals( Block $block ) {
                return (
                        (string)$this->target == (string)$block->target
                        && $this->type == $block->type
                        && $this->mAuto == $block->mAuto
                        && $this->isHardblock() == $block->isHardblock()
                        && $this->prevents( 'createaccount' ) == $block->prevents( 'createaccount' )
                        && $this->mExpiry == $block->mExpiry
                        && $this->isAutoblocking() == $block->isAutoblocking()
                        && $this->mHideName == $block->mHideName
                        && $this->prevents( 'sendemail' ) == $block->prevents( 'sendemail' )
                        && $this->prevents( 'editownusertalk' ) == $block->prevents( 'editownusertalk' )
                        && $this->mReason == $block->mReason
                );
        }

        /**
         * Load a block from the database which affects the already-set $this->target:
         *     1) A block directly on the given user or IP
         *     2) A rangeblock encompassing the given IP (smallest first)
         *     3) An autoblock on the given IP
         * @param User|string $vagueTarget Also search for blocks affecting this target.  Doesn't
         *     make any sense to use TYPE_AUTO / TYPE_ID here. Leave blank to skip IP lookups.
         * @throws MWException
         * @return bool Whether a relevant block was found
         */
        protected function newLoad( $vagueTarget = null ) {
                $db = wfGetDB( $this->mFromMaster ? DB_MASTER : DB_REPLICA );

                if ( $this->type !== null ) {
                        $conds = [
                                'ipb_address' => [ (string)$this->target ],
                        ];
                } else {
                        $conds = [ 'ipb_address' => [] ];
                }

                # Be aware that the != '' check is explicit, since empty values will be
                # passed by some callers (bug 29116)
                if ( $vagueTarget != '' ) {
                        list( $target, $type ) = self::parseTarget( $vagueTarget );
                        switch ( $type ) {
                                case self::TYPE_USER:
                                        # Slightly weird, but who are we to argue?
                                        $conds['ipb_address'][] = (string)$target;
                                        break;

                                case self::TYPE_IP:
                                        $conds['ipb_address'][] = (string)$target;
                                        $conds[] = self::getRangeCond( IP::toHex( $target ) );
                                        $conds = $db->makeList( $conds, LIST_OR );
                                        break;

                                case self::TYPE_RANGE:
                                        list( $start, $end ) = IP::parseRange( $target );
                                        $conds['ipb_address'][] = (string)$target;
                                        $conds[] = self::getRangeCond( $start, $end );
                                        $conds = $db->makeList( $conds, LIST_OR );
                                        break;

                                default:
                                        throw new MWException( "Tried to load block with invalid type" );
                        }
                }

                $res = $db->select( 'ipblocks', self::selectFields(), $conds, __METHOD__ );

                # This result could contain a block on the user, a block on the IP, and a russian-doll
                # set of rangeblocks.  We want to choose the most specific one, so keep a leader board.
                $bestRow = null;

                # Lower will be better
                $bestBlockScore = 100;

                # This is begging for $this = $bestBlock, but that's not allowed in PHP :(
                $bestBlockPreventsEdit = null;

                foreach ( $res as $row ) {
                        $block = self::newFromRow( $row );

                        # Don't use expired blocks
                        if ( $block->isExpired() ) {
                                continue;
                        }

                        # Don't use anon only blocks on users
                        if ( $this->type == self::TYPE_USER && !$block->isHardblock() ) {
                                continue;
                        }

                        if ( $block->getType() == self::TYPE_RANGE ) {
                                # This is the number of bits that are allowed to vary in the block, give
                                # or take some floating point errors
                                $end = Wikimedia\base_convert( $block->getRangeEnd(), 16, 10 );
                                $start = Wikimedia\base_convert( $block->getRangeStart(), 16, 10 );
                                $size = log( $end - $start + 1, 2 );

                                # This has the nice property that a /32 block is ranked equally with a
                                # single-IP block, which is exactly what it is...
                                $score = self::TYPE_RANGE - 1 + ( $size / 128 );

                        } else {
                                $score = $block->getType();
                        }

                        if ( $score < $bestBlockScore ) {
                                $bestBlockScore = $score;
                                $bestRow = $row;
                                $bestBlockPreventsEdit = $block->prevents( 'edit' );
                        }
                }

                if ( $bestRow !== null ) {
                        $this->initFromRow( $bestRow );
                        $this->prevents( 'edit', $bestBlockPreventsEdit );
                        return true;
                } else {
                        return false;
                }
        }

        /**
         * Get a set of SQL conditions which will select rangeblocks encompassing a given range
         * @param string $start Hexadecimal IP representation
         * @param string $end Hexadecimal IP representation, or null to use $start = $end
         * @return string
         */
        public static function getRangeCond( $start, $end = null ) {
                if ( $end === null ) {
                        $end = $start;
                }
                # Per bug 14634, we want to include relevant active rangeblocks; for
                # rangeblocks, we want to include larger ranges which enclose the given
                # range. We know that all blocks must be smaller than $wgBlockCIDRLimit,
                # so we can improve performance by filtering on a LIKE clause
                $chunk = self::getIpFragment( $start );
                $dbr = wfGetDB( DB_REPLICA );
                $like = $dbr->buildLike( $chunk, $dbr->anyString() );

                # Fairly hard to make a malicious SQL statement out of hex characters,
                # but stranger things have happened...
                $safeStart = $dbr->addQuotes( $start );
                $safeEnd = $dbr->addQuotes( $end );

                return $dbr->makeList(
                        [
                                "ipb_range_start $like",
                                "ipb_range_start <= $safeStart",
                                "ipb_range_end >= $safeEnd",
                        ],
                        LIST_AND
                );
        }

        /**
         * Get the component of an IP address which is certain to be the same between an IP
         * address and a rangeblock containing that IP address.
         * @param string $hex Hexadecimal IP representation
         * @return string
         */
        protected static function getIpFragment( $hex ) {
                global $wgBlockCIDRLimit;
                if ( substr( $hex, 0, 3 ) == 'v6-' ) {
                        return 'v6-' . substr( substr( $hex, 3 ), 0, floor( $wgBlockCIDRLimit['IPv6'] / 4 ) );
                } else {
                        return substr( $hex, 0, floor( $wgBlockCIDRLimit['IPv4'] / 4 ) );
                }
        }

        /**
         * Given a database row from the ipblocks table, initialize
         * member variables
         * @param stdClass $row A row from the ipblocks table
         */
        protected function initFromRow( $row ) {
                $this->setTarget( $row->ipb_address );
                if ( $row->ipb_by ) { // local user
                        $this->setBlocker( User::newFromId( $row->ipb_by ) );
                } else { // foreign user
                        $this->setBlocker( $row->ipb_by_text );
                }

                $this->mReason = $row->ipb_reason;
                $this->mTimestamp = wfTimestamp( TS_MW, $row->ipb_timestamp );
                $this->mAuto = $row->ipb_auto;
                $this->mHideName = $row->ipb_deleted;
                $this->mId = (int)$row->ipb_id;
                $this->mParentBlockId = $row->ipb_parent_block_id;

                // I wish I didn't have to do this
                $this->mExpiry = wfGetDB( DB_REPLICA )->decodeExpiry( $row->ipb_expiry );

                $this->isHardblock( !$row->ipb_anon_only );
                $this->isAutoblocking( $row->ipb_enable_autoblock );

                $this->prevents( 'createaccount', $row->ipb_create_account );
                $this->prevents( 'sendemail', $row->ipb_block_email );
                $this->prevents( 'editownusertalk', !$row->ipb_allow_usertalk );
        }

        /**
         * Create a new Block object from a database row
         * @param stdClass $row Row from the ipblocks table
         * @return Block
         */
        public static function newFromRow( $row ) {
                $block = new Block;
                $block->initFromRow( $row );
                return $block;
        }

        /**
         * Delete the row from the IP blocks table.
         *
         * @throws MWException
         * @return bool
         */
        public function delete() {
                if ( wfReadOnly() ) {
                        return false;
                }

                if ( !$this->getId() ) {
                        throw new MWException( "Block::delete() requires that the mId member be filled\n" );
                }

                $dbw = wfGetDB( DB_MASTER );
                $dbw->delete( 'ipblocks', [ 'ipb_parent_block_id' => $this->getId() ], __METHOD__ );
                $dbw->delete( 'ipblocks', [ 'ipb_id' => $this->getId() ], __METHOD__ );

                return $dbw->affectedRows() > 0;
        }

        /**
         * Insert a block into the block table. Will fail if there is a conflicting
         * block (same name and options) already in the database.
         *
         * @param IDatabase $dbw If you have one available
         * @return bool|array False on failure, assoc array on success:
         *      ('id' => block ID, 'autoIds' => array of autoblock IDs)
         */
        public function insert( $dbw = null ) {
                global $wgBlockDisablesLogin;

                if ( $this->getSystemBlockType() !== null ) {
                        throw new MWException( 'Cannot insert a system block into the database' );
                }

                wfDebug( "Block::insert; timestamp {$this->mTimestamp}\n" );

                if ( $dbw === null ) {
                        $dbw = wfGetDB( DB_MASTER );
                }

                # Periodic purge via commit hooks
                if ( mt_rand( 0, 9 ) == 0 ) {
                        Block::purgeExpired();
                }

                $row = $this->getDatabaseArray();
                $row['ipb_id'] = $dbw->nextSequenceValue( "ipblocks_ipb_id_seq" );

                $dbw->insert( 'ipblocks', $row, __METHOD__, [ 'IGNORE' ] );
                $affected = $dbw->affectedRows();
                $this->mId = $dbw->insertId();

                # Don't collide with expired blocks.
                # Do this after trying to insert to avoid locking.
                if ( !$affected ) {
                        # T96428: The ipb_address index uses a prefix on a field, so
                        # use a standard SELECT + DELETE to avoid annoying gap locks.
                        $ids = $dbw->selectFieldValues( 'ipblocks',
                                'ipb_id',
                                [
                                        'ipb_address' => $row['ipb_address'],
                                        'ipb_user' => $row['ipb_user'],
                                        'ipb_expiry < ' . $dbw->addQuotes( $dbw->timestamp() )
                                ],
                                __METHOD__
                        );
                        if ( $ids ) {
                                $dbw->delete( 'ipblocks', [ 'ipb_id' => $ids ], __METHOD__ );
                                $dbw->insert( 'ipblocks', $row, __METHOD__, [ 'IGNORE' ] );
                                $affected = $dbw->affectedRows();
                                $this->mId = $dbw->insertId();
                        }
                }

                if ( $affected ) {
                        $auto_ipd_ids = $this->doRetroactiveAutoblock();

                        if ( $wgBlockDisablesLogin && $this->target instanceof User ) {
                                // Change user login token to force them to be logged out.
                                $this->target->setToken();
                                $this->target->saveSettings();
                        }

                        return [ 'id' => $this->mId, 'autoIds' => $auto_ipd_ids ];
                }

                return false;
        }

        /**
         * Update a block in the DB with new parameters.
         * The ID field needs to be loaded first.
         *
         * @return bool|array False on failure, array on success:
         *   ('id' => block ID, 'autoIds' => array of autoblock IDs)
         */
        public function update() {
                wfDebug( "Block::update; timestamp {$this->mTimestamp}\n" );
                $dbw = wfGetDB( DB_MASTER );

                $dbw->startAtomic( __METHOD__ );

                $dbw->update(
                        'ipblocks',
                        $this->getDatabaseArray( $dbw ),
                        [ 'ipb_id' => $this->getId() ],
                        __METHOD__
                );

                $affected = $dbw->affectedRows();

                if ( $this->isAutoblocking() ) {
                        // update corresponding autoblock(s) (bug 48813)
                        $dbw->update(
                                'ipblocks',
                                $this->getAutoblockUpdateArray(),
                                [ 'ipb_parent_block_id' => $this->getId() ],
                                __METHOD__
                        );
                } else {
                        // autoblock no longer required, delete corresponding autoblock(s)
                        $dbw->delete(
                                'ipblocks',
                                [ 'ipb_parent_block_id' => $this->getId() ],
                                __METHOD__
                        );
                }

                $dbw->endAtomic( __METHOD__ );

                if ( $affected ) {
                        $auto_ipd_ids = $this->doRetroactiveAutoblock();
                        return [ 'id' => $this->mId, 'autoIds' => $auto_ipd_ids ];
                }

                return false;
        }

        /**
         * Get an array suitable for passing to $dbw->insert() or $dbw->update()
         * @param IDatabase $db
         * @return array
         */
        protected function getDatabaseArray( $db = null ) {
                if ( !$db ) {
                        $db = wfGetDB( DB_REPLICA );
                }
                $expiry = $db->encodeExpiry( $this->mExpiry );

                if ( $this->forcedTargetID ) {
                        $uid = $this->forcedTargetID;
                } else {
                        $uid = $this->target instanceof User ? $this->target->getId() : 0;
                }

                $a = [
                        'ipb_address'          => (string)$this->target,
                        'ipb_user'             => $uid,
                        'ipb_by'               => $this->getBy(),
                        'ipb_by_text'          => $this->getByName(),
                        'ipb_reason'           => $this->mReason,
                        'ipb_timestamp'        => $db->timestamp( $this->mTimestamp ),
                        'ipb_auto'             => $this->mAuto,
                        'ipb_anon_only'        => !$this->isHardblock(),
                        'ipb_create_account'   => $this->prevents( 'createaccount' ),
                        'ipb_enable_autoblock' => $this->isAutoblocking(),
                        'ipb_expiry'           => $expiry,
                        'ipb_range_start'      => $this->getRangeStart(),
                        'ipb_range_end'        => $this->getRangeEnd(),
                        'ipb_deleted'          => intval( $this->mHideName ), // typecast required for SQLite
                        'ipb_block_email'      => $this->prevents( 'sendemail' ),
                        'ipb_allow_usertalk'   => !$this->prevents( 'editownusertalk' ),
                        'ipb_parent_block_id'  => $this->mParentBlockId
                ];

                return $a;
        }

        /**
         * @return array
         */
        protected function getAutoblockUpdateArray() {
                return [
                        'ipb_by'               => $this->getBy(),
                        'ipb_by_text'          => $this->getByName(),
                        'ipb_reason'           => $this->mReason,
                        'ipb_create_account'   => $this->prevents( 'createaccount' ),
                        'ipb_deleted'          => (int)$this->mHideName, // typecast required for SQLite
                        'ipb_allow_usertalk'   => !$this->prevents( 'editownusertalk' ),
                ];
        }

        /**
         * Retroactively autoblocks the last IP used by the user (if it is a user)
         * blocked by this Block.
         *
         * @return array Block IDs of retroactive autoblocks made
         */
        protected function doRetroactiveAutoblock() {
                $blockIds = [];
                # If autoblock is enabled, autoblock the LAST IP(s) used
                if ( $this->isAutoblocking() && $this->getType() == self::TYPE_USER ) {
                        wfDebug( "Doing retroactive autoblocks for " . $this->getTarget() . "\n" );

                        $continue = Hooks::run(
                                'PerformRetroactiveAutoblock', [ $this, &$blockIds ] );

                        if ( $continue ) {
                                self::defaultRetroactiveAutoblock( $this, $blockIds );
                        }
                }
                return $blockIds;
        }

        /**
         * Retroactively autoblocks the last IP used by the user (if it is a user)
         * blocked by this Block. This will use the recentchanges table.
         *
         * @param Block $block
         * @param array &$blockIds
         */
        protected static function defaultRetroactiveAutoblock( Block $block, array &$blockIds ) {
                global $wgPutIPinRC;

                // No IPs are in recentchanges table, so nothing to select
                if ( !$wgPutIPinRC ) {
                        return;
                }

                $dbr = wfGetDB( DB_REPLICA );

                $options = [ 'ORDER BY' => 'rc_timestamp DESC' ];
                $conds = [ 'rc_user_text' => (string)$block->getTarget() ];

                // Just the last IP used.
                $options['LIMIT'] = 1;

                $res = $dbr->select( 'recentchanges', [ 'rc_ip' ], $conds,
                        __METHOD__, $options );

                if ( !$res->numRows() ) {
                        # No results, don't autoblock anything
                        wfDebug( "No IP found to retroactively autoblock\n" );
                } else {
                        foreach ( $res as $row ) {
                                if ( $row->rc_ip ) {
                                        $id = $block->doAutoblock( $row->rc_ip );
                                        if ( $id ) {
                                                $blockIds[] = $id;
                                        }
                                }
                        }
                }
        }

        /**
         * Checks whether a given IP is on the autoblock whitelist.
         * TODO: this probably belongs somewhere else, but not sure where...
         *
         * @param string $ip The IP to check
         * @return bool
         */
        public static function isWhitelistedFromAutoblocks( $ip ) {
                // Try to get the autoblock_whitelist from the cache, as it's faster
                // than getting the msg raw and explode()'ing it.
                $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
                $lines = $cache->getWithSetCallback(
                        wfMemcKey( 'ipb', 'autoblock', 'whitelist' ),
                        $cache::TTL_DAY,
                        function ( $curValue, &$ttl, array &$setOpts ) {
                                $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );

                                return explode( "\n",
                                        wfMessage( 'autoblock_whitelist' )->inContentLanguage()->plain() );
                        }
                );

                wfDebug( "Checking the autoblock whitelist..\n" );

                foreach ( $lines as $line ) {
                        # List items only
                        if ( substr( $line, 0, 1 ) !== '*' ) {
                                continue;
                        }

                        $wlEntry = substr( $line, 1 );
                        $wlEntry = trim( $wlEntry );

                        wfDebug( "Checking $ip against $wlEntry..." );

                        # Is the IP in this range?
                        if ( IP::isInRange( $ip, $wlEntry ) ) {
                                wfDebug( " IP $ip matches $wlEntry, not autoblocking\n" );
                                return true;
                        } else {
                                wfDebug( " No match\n" );
                        }
                }

                return false;
        }

        /**
         * Autoblocks the given IP, referring to this Block.
         *
         * @param string $autoblockIP The IP to autoblock.
         * @return int|bool Block ID if an autoblock was inserted, false if not.
         */
        public function doAutoblock( $autoblockIP ) {
                # If autoblocks are disabled, go away.
                if ( !$this->isAutoblocking() ) {
                        return false;
                }

                # Don't autoblock for system blocks
                if ( $this->getSystemBlockType() !== null ) {
                        throw new MWException( 'Cannot autoblock from a system block' );
                }

                # Check for presence on the autoblock whitelist.
                if ( self::isWhitelistedFromAutoblocks( $autoblockIP ) ) {
                        return false;
                }

                // Avoid PHP 7.1 warning of passing $this by reference
                $block = $this;
                # Allow hooks to cancel the autoblock.
                if ( !Hooks::run( 'AbortAutoblock', [ $autoblockIP, &$block ] ) ) {
                        wfDebug( "Autoblock aborted by hook.\n" );
                        return false;
                }

                # It's okay to autoblock. Go ahead and insert/update the block...

                # Do not add a *new* block if the IP is already blocked.
                $ipblock = Block::newFromTarget( $autoblockIP );
                if ( $ipblock ) {
                        # Check if the block is an autoblock and would exceed the user block
                        # if renewed. If so, do nothing, otherwise prolong the block time...
                        if ( $ipblock->mAuto && // @todo Why not compare $ipblock->mExpiry?
                                $this->mExpiry > Block::getAutoblockExpiry( $ipblock->mTimestamp )
                        ) {
                                # Reset block timestamp to now and its expiry to
                                # $wgAutoblockExpiry in the future
                                $ipblock->updateTimestamp();
                        }
                        return false;
                }

                # Make a new block object with the desired properties.
                $autoblock = new Block;
                wfDebug( "Autoblocking {$this->getTarget()}@" . $autoblockIP . "\n" );
                $autoblock->setTarget( $autoblockIP );
                $autoblock->setBlocker( $this->getBlocker() );
                $autoblock->mReason = wfMessage( 'autoblocker', $this->getTarget(), $this->mReason )
                        ->inContentLanguage()->plain();
                $timestamp = wfTimestampNow();
                $autoblock->mTimestamp = $timestamp;
                $autoblock->mAuto = 1;
                $autoblock->prevents( 'createaccount', $this->prevents( 'createaccount' ) );
                # Continue suppressing the name if needed
                $autoblock->mHideName = $this->mHideName;
                $autoblock->prevents( 'editownusertalk', $this->prevents( 'editownusertalk' ) );
                $autoblock->mParentBlockId = $this->mId;

                if ( $this->mExpiry == 'infinity' ) {
                        # Original block was indefinite, start an autoblock now
                        $autoblock->mExpiry = Block::getAutoblockExpiry( $timestamp );
                } else {
                        # If the user is already blocked with an expiry date, we don't
                        # want to pile on top of that.
                        $autoblock->mExpiry = min( $this->mExpiry, Block::getAutoblockExpiry( $timestamp ) );
                }

                # Insert the block...
                $status = $autoblock->insert();
                return $status
                        ? $status['id']
                        : false;
        }

        /**
         * Check if a block has expired. Delete it if it is.
         * @return bool
         */
        public function deleteIfExpired() {

                if ( $this->isExpired() ) {
                        wfDebug( "Block::deleteIfExpired() -- deleting\n" );
                        $this->delete();
                        $retVal = true;
                } else {
                        wfDebug( "Block::deleteIfExpired() -- not expired\n" );
                        $retVal = false;
                }

                return $retVal;
        }

        /**
         * Has the block expired?
         * @return bool
         */
        public function isExpired() {
                $timestamp = wfTimestampNow();
                wfDebug( "Block::isExpired() checking current " . $timestamp . " vs $this->mExpiry\n" );

                if ( !$this->mExpiry ) {
                        return false;
                } else {
                        return $timestamp > $this->mExpiry;
                }
        }

        /**
         * Is the block address valid (i.e. not a null string?)
         * @return bool
         */
        public function isValid() {
                return $this->getTarget() != null;
        }

        /**
         * Update the timestamp on autoblocks.
         */
        public function updateTimestamp() {
                if ( $this->mAuto ) {
                        $this->mTimestamp = wfTimestamp();
                        $this->mExpiry = Block::getAutoblockExpiry( $this->mTimestamp );

                        $dbw = wfGetDB( DB_MASTER );
                        $dbw->update( 'ipblocks',
                                [ /* SET */
                                        'ipb_timestamp' => $dbw->timestamp( $this->mTimestamp ),
                                        'ipb_expiry' => $dbw->timestamp( $this->mExpiry ),
                                ],
                                [ /* WHERE */
                                        'ipb_id' => $this->getId(),
                                ],
                                __METHOD__
                        );
                }
        }

        /**
         * Get the IP address at the start of the range in Hex form
         * @throws MWException
         * @return string IP in Hex form
         */
        public function getRangeStart() {
                switch ( $this->type ) {
                        case self::TYPE_USER:
                                return '';
                        case self::TYPE_IP:
                                return IP::toHex( $this->target );
                        case self::TYPE_RANGE:
                                list( $start, /*...*/ ) = IP::parseRange( $this->target );
                                return $start;
                        default:
                                throw new MWException( "Block with invalid type" );
                }
        }

        /**
         * Get the IP address at the end of the range in Hex form
         * @throws MWException
         * @return string IP in Hex form
         */
        public function getRangeEnd() {
                switch ( $this->type ) {
                        case self::TYPE_USER:
                                return '';
                        case self::TYPE_IP:
                                return IP::toHex( $this->target );
                        case self::TYPE_RANGE:
                                list( /*...*/, $end ) = IP::parseRange( $this->target );
                                return $end;
                        default:
                                throw new MWException( "Block with invalid type" );
                }
        }

        /**
         * Get the user id of the blocking sysop
         *
         * @return int (0 for foreign users)
         */
        public function getBy() {
                $blocker = $this->getBlocker();
                return ( $blocker instanceof User )
                        ? $blocker->getId()
                        : 0;
        }

        /**
         * Get the username of the blocking sysop
         *
         * @return string
         */
        public function getByName() {
                $blocker = $this->getBlocker();
                return ( $blocker instanceof User )
                        ? $blocker->getName()
                        : (string)$blocker; // username
        }

        /**
         * Get the block ID
         * @return int
         */
        public function getId() {
                return $this->mId;
        }

        /**
         * Get the system block type, if any
         * @return string|null
         */
        public function getSystemBlockType() {
                return $this->systemBlockType;
        }

        /**
         * Get/set a flag determining whether the master is used for reads
         *
         * @param bool|null $x
         * @return bool
         */
        public function fromMaster( $x = null ) {
                return wfSetVar( $this->mFromMaster, $x );
        }

        /**
         * Get/set whether the Block is a hardblock (affects logged-in users on a given IP/range)
         * @param bool|null $x
         * @return bool
         */
        public function isHardblock( $x = null ) {
                wfSetVar( $this->isHardblock, $x );

                # You can't *not* hardblock a user
                return $this->getType() == self::TYPE_USER
                        ? true
                        : $this->isHardblock;
        }

        /**
         * @param null|bool $x
         * @return bool
         */
        public function isAutoblocking( $x = null ) {
                wfSetVar( $this->isAutoblocking, $x );

                # You can't put an autoblock on an IP or range as we don't have any history to
                # look over to get more IPs from
                return $this->getType() == self::TYPE_USER
                        ? $this->isAutoblocking
                        : false;
        }

        /**
         * Get/set whether the Block prevents a given action
         *
         * @param string $action Action to check
         * @param bool|null $x Value for set, or null to just get value
         * @return bool|null Null for unrecognized rights.
         */
        public function prevents( $action, $x = null ) {
                global $wgBlockDisablesLogin;
                $res = null;
                switch ( $action ) {
                        case 'edit':
                                # For now... <evil laugh>
                                $res = true;
                                break;
                        case 'createaccount':
                                $res = wfSetVar( $this->mCreateAccount, $x );
                                break;
                        case 'sendemail':
                                $res = wfSetVar( $this->mBlockEmail, $x );
                                break;
                        case 'editownusertalk':
                                $res = wfSetVar( $this->mDisableUsertalk, $x );
                                break;
                        case 'read':
                                $res = false;
                                break;
                }
                if ( !$res && $wgBlockDisablesLogin ) {
                        // If a block would disable login, then it should
                        // prevent any action that all users cannot do
                        $anon = new User;
                        $res = $anon->isAllowed( $action ) ? $res : true;
                }

                return $res;
        }

        /**
         * Get the block name, but with autoblocked IPs hidden as per standard privacy policy
         * @return string Text is escaped
         */
        public function getRedactedName() {
                if ( $this->mAuto ) {
                        return Html::rawElement(
                                'span',
                                [ 'class' => 'mw-autoblockid' ],
                                wfMessage( 'autoblockid', $this->mId )
                        );
                } else {
                        return htmlspecialchars( $this->getTarget() );
                }
        }

        /**
         * Get a timestamp of the expiry for autoblocks
         *
         * @param string|int $timestamp
         * @return string
         */
        public static function getAutoblockExpiry( $timestamp ) {
                global $wgAutoblockExpiry;

                return wfTimestamp( TS_MW, wfTimestamp( TS_UNIX, $timestamp ) + $wgAutoblockExpiry );
        }

        /**
         * Purge expired blocks from the ipblocks table
         */
        public static function purgeExpired() {
                if ( wfReadOnly() ) {
                        return;
                }

                DeferredUpdates::addUpdate( new AtomicSectionUpdate(
                        wfGetDB( DB_MASTER ),
                        __METHOD__,
                        function ( IDatabase $dbw, $fname ) {
                                $dbw->delete(
                                        'ipblocks',
                                        [ 'ipb_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ],
                                        $fname
                                );
                        }
                ) );
        }

        /**
         * Given a target and the target's type, get an existing Block object if possible.
         * @param string|User|int $specificTarget A block target, which may be one of several types:
         *     * A user to block, in which case $target will be a User
         *     * An IP to block, in which case $target will be a User generated by using
         *       User::newFromName( $ip, false ) to turn off name validation
         *     * An IP range, in which case $target will be a String "123.123.123.123/18" etc
         *     * The ID of an existing block, in the format "#12345" (since pure numbers are valid
         *       usernames
         *     Calling this with a user, IP address or range will not select autoblocks, and will
         *     only select a block where the targets match exactly (so looking for blocks on
         *     1.2.3.4 will not select 1.2.0.0/16 or even 1.2.3.4/32)
         * @param string|User|int $vagueTarget As above, but we will search for *any* block which
         *     affects that target (so for an IP address, get ranges containing that IP; and also
         *     get any relevant autoblocks). Leave empty or blank to skip IP-based lookups.
         * @param bool $fromMaster Whether to use the DB_MASTER database
         * @return Block|null (null if no relevant block could be found).  The target and type
         *     of the returned Block will refer to the actual block which was found, which might
         *     not be the same as the target you gave if you used $vagueTarget!
         */
        public static function newFromTarget( $specificTarget, $vagueTarget = null, $fromMaster = false ) {

                list( $target, $type ) = self::parseTarget( $specificTarget );
                if ( $type == Block::TYPE_ID || $type == Block::TYPE_AUTO ) {
                        return Block::newFromID( $target );

                } elseif ( $target === null && $vagueTarget == '' ) {
                        # We're not going to find anything useful here
                        # Be aware that the == '' check is explicit, since empty values will be
                        # passed by some callers (bug 29116)
                        return null;

                } elseif ( in_array(
                        $type,
                        [ Block::TYPE_USER, Block::TYPE_IP, Block::TYPE_RANGE, null ] )
                ) {
                        $block = new Block();
                        $block->fromMaster( $fromMaster );

                        if ( $type !== null ) {
                                $block->setTarget( $target );
                        }

                        if ( $block->newLoad( $vagueTarget ) ) {
                                return $block;
                        }
                }
                return null;
        }

        /**
         * Get all blocks that match any IP from an array of IP addresses
         *
         * @param array $ipChain List of IPs (strings), usually retrieved from the
         *         X-Forwarded-For header of the request
         * @param bool $isAnon Exclude anonymous-only blocks if false
         * @param bool $fromMaster Whether to query the master or replica DB
         * @return array Array of Blocks
         * @since 1.22
         */
        public static function getBlocksForIPList( array $ipChain, $isAnon, $fromMaster = false ) {
                if ( !count( $ipChain ) ) {
                        return [];
                }

                $conds = [];
                $proxyLookup = MediaWikiServices::getInstance()->getProxyLookup();
                foreach ( array_unique( $ipChain ) as $ipaddr ) {
                        # Discard invalid IP addresses. Since XFF can be spoofed and we do not
                        # necessarily trust the header given to us, make sure that we are only
                        # checking for blocks on well-formatted IP addresses (IPv4 and IPv6).
                        # Do not treat private IP spaces as special as it may be desirable for wikis
                        # to block those IP ranges in order to stop misbehaving proxies that spoof XFF.
                        if ( !IP::isValid( $ipaddr ) ) {
                                continue;
                        }
                        # Don't check trusted IPs (includes local squids which will be in every request)
                        if ( $proxyLookup->isTrustedProxy( $ipaddr ) ) {
                                continue;
                        }
                        # Check both the original IP (to check against single blocks), as well as build
                        # the clause to check for rangeblocks for the given IP.
                        $conds['ipb_address'][] = $ipaddr;
                        $conds[] = self::getRangeCond( IP::toHex( $ipaddr ) );
                }

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

                if ( $fromMaster ) {
                        $db = wfGetDB( DB_MASTER );
                } else {
                        $db = wfGetDB( DB_REPLICA );
                }
                $conds = $db->makeList( $conds, LIST_OR );
                if ( !$isAnon ) {
                        $conds = [ $conds, 'ipb_anon_only' => 0 ];
                }
                $selectFields = array_merge(
                        [ 'ipb_range_start', 'ipb_range_end' ],
                        Block::selectFields()
                );
                $rows = $db->select( 'ipblocks',
                        $selectFields,
                        $conds,
                        __METHOD__
                );

                $blocks = [];
                foreach ( $rows as $row ) {
                        $block = self::newFromRow( $row );
                        if ( !$block->isExpired() ) {
                                $blocks[] = $block;
                        }
                }

                return $blocks;
        }

        /**
         * From a list of multiple blocks, find the most exact and strongest Block.
         *
         * The logic for finding the "best" block is:
         *  - Blocks that match the block's target IP are preferred over ones in a range
         *  - Hardblocks are chosen over softblocks that prevent account creation
         *  - Softblocks that prevent account creation are chosen over other softblocks
         *  - Other softblocks are chosen over autoblocks
         *  - If there are multiple exact or range blocks at the same level, the one chosen
         *    is random
         * This should be used when $blocks where retrieved from the user's IP address
         * and $ipChain is populated from the same IP address information.
         *
         * @param array $blocks Array of Block objects
         * @param array $ipChain List of IPs (strings). This is used to determine how "close"
         *        a block is to the server, and if a block matches exactly, or is in a range.
         *        The order is furthest from the server to nearest e.g., (Browser, proxy1, proxy2,
         *        local-squid, ...)
         * @throws MWException
         * @return Block|null The "best" block from the list
         */
        public static function chooseBlock( array $blocks, array $ipChain ) {
                if ( !count( $blocks ) ) {
                        return null;
                } elseif ( count( $blocks ) == 1 ) {
                        return $blocks[0];
                }

                // Sort hard blocks before soft ones and secondarily sort blocks
                // that disable account creation before those that don't.
                usort( $blocks, function ( Block $a, Block $b ) {
                        $aWeight = (int)$a->isHardblock() . (int)$a->prevents( 'createaccount' );
                        $bWeight = (int)$b->isHardblock() . (int)$b->prevents( 'createaccount' );
                        return strcmp( $bWeight, $aWeight ); // highest weight first
                } );

                $blocksListExact = [
                        'hard' => false,
                        'disable_create' => false,
                        'other' => false,
                        'auto' => false
                ];
                $blocksListRange = [
                        'hard' => false,
                        'disable_create' => false,
                        'other' => false,
                        'auto' => false
                ];
                $ipChain = array_reverse( $ipChain );

                /** @var Block $block */
                foreach ( $blocks as $block ) {
                        // Stop searching if we have already have a "better" block. This
                        // is why the order of the blocks matters
                        if ( !$block->isHardblock() && $blocksListExact['hard'] ) {
                                break;
                        } elseif ( !$block->prevents( 'createaccount' ) && $blocksListExact['disable_create'] ) {
                                break;
                        }

                        foreach ( $ipChain as $checkip ) {
                                $checkipHex = IP::toHex( $checkip );
                                if ( (string)$block->getTarget() === $checkip ) {
                                        if ( $block->isHardblock() ) {
                                                $blocksListExact['hard'] = $blocksListExact['hard'] ?: $block;
                                        } elseif ( $block->prevents( 'createaccount' ) ) {
                                                $blocksListExact['disable_create'] = $blocksListExact['disable_create'] ?: $block;
                                        } elseif ( $block->mAuto ) {
                                                $blocksListExact['auto'] = $blocksListExact['auto'] ?: $block;
                                        } else {
                                                $blocksListExact['other'] = $blocksListExact['other'] ?: $block;
                                        }
                                        // We found closest exact match in the ip list, so go to the next Block
                                        break;
                                } elseif ( array_filter( $blocksListExact ) == []
                                        && $block->getRangeStart() <= $checkipHex
                                        && $block->getRangeEnd() >= $checkipHex
                                ) {
                                        if ( $block->isHardblock() ) {
                                                $blocksListRange['hard'] = $blocksListRange['hard'] ?: $block;
                                        } elseif ( $block->prevents( 'createaccount' ) ) {
                                                $blocksListRange['disable_create'] = $blocksListRange['disable_create'] ?: $block;
                                        } elseif ( $block->mAuto ) {
                                                $blocksListRange['auto'] = $blocksListRange['auto'] ?: $block;
                                        } else {
                                                $blocksListRange['other'] = $blocksListRange['other'] ?: $block;
                                        }
                                        break;
                                }
                        }
                }

                if ( array_filter( $blocksListExact ) == [] ) {
                        $blocksList = &$blocksListRange;
                } else {
                        $blocksList = &$blocksListExact;
                }

                $chosenBlock = null;
                if ( $blocksList['hard'] ) {
                        $chosenBlock = $blocksList['hard'];
                } elseif ( $blocksList['disable_create'] ) {
                        $chosenBlock = $blocksList['disable_create'];
                } elseif ( $blocksList['other'] ) {
                        $chosenBlock = $blocksList['other'];
                } elseif ( $blocksList['auto'] ) {
                        $chosenBlock = $blocksList['auto'];
                } else {
                        throw new MWException( "Proxy block found, but couldn't be classified." );
                }

                return $chosenBlock;
        }

        /**
         * From an existing Block, get the target and the type of target.
         * Note that, except for null, it is always safe to treat the target
         * as a string; for User objects this will return User::__toString()
         * which in turn gives User::getName().
         *
         * @param string|int|User|null $target
         * @return array( User|String|null, Block::TYPE_ constant|null )
         */
        public static function parseTarget( $target ) {
                # We may have been through this before
                if ( $target instanceof User ) {
                        if ( IP::isValid( $target->getName() ) ) {
                                return [ $target, self::TYPE_IP ];
                        } else {
                                return [ $target, self::TYPE_USER ];
                        }
                } elseif ( $target === null ) {
                        return [ null, null ];
                }

                $target = trim( $target );

                if ( IP::isValid( $target ) ) {
                        # We can still create a User if it's an IP address, but we need to turn
                        # off validation checking (which would exclude IP addresses)
                        return [
                                User::newFromName( IP::sanitizeIP( $target ), false ),
                                Block::TYPE_IP
                        ];

                } elseif ( IP::isValidBlock( $target ) ) {
                        # Can't create a User from an IP range
                        return [ IP::sanitizeRange( $target ), Block::TYPE_RANGE ];
                }

                # Consider the possibility that this is not a username at all
                # but actually an old subpage (bug #29797)
                if ( strpos( $target, '/' ) !== false ) {
                        # An old subpage, drill down to the user behind it
                        $target = explode( '/', $target )[0];
                }

                $userObj = User::newFromName( $target );
                if ( $userObj instanceof User ) {
                        # Note that since numbers are valid usernames, a $target of "12345" will be
                        # considered a User.  If you want to pass a block ID, prepend a hash "#12345",
                        # since hash characters are not valid in usernames or titles generally.
                        return [ $userObj, Block::TYPE_USER ];

                } elseif ( preg_match( '/^#\d+$/', $target ) ) {
                        # Autoblock reference in the form "#12345"
                        return [ substr( $target, 1 ), Block::TYPE_AUTO ];

                } else {
                        # WTF?
                        return [ null, null ];
                }
        }

        /**
         * Get the type of target for this particular block
         * @return int Block::TYPE_ constant, will never be TYPE_ID
         */
        public function getType() {
                return $this->mAuto
                        ? self::TYPE_AUTO
                        : $this->type;
        }

        /**
         * Get the target and target type for this particular Block.  Note that for autoblocks,
         * this returns the unredacted name; frontend functions need to call $block->getRedactedName()
         * in this situation.
         * @return array( User|String, Block::TYPE_ constant )
         * @todo FIXME: This should be an integral part of the Block member variables
         */
        public function getTargetAndType() {
                return [ $this->getTarget(), $this->getType() ];
        }

        /**
         * Get the target for this particular Block.  Note that for autoblocks,
         * this returns the unredacted name; frontend functions need to call $block->getRedactedName()
         * in this situation.
         * @return User|string
         */
        public function getTarget() {
                return $this->target;
        }

        /**
         * @since 1.19
         *
         * @return mixed|string
         */
        public function getExpiry() {
                return $this->mExpiry;
        }

        /**
         * Set the target for this block, and update $this->type accordingly
         * @param mixed $target
         */
        public function setTarget( $target ) {
                list( $this->target, $this->type ) = self::parseTarget( $target );
        }

        /**
         * Get the user who implemented this block
         * @return User|string Local User object or string for a foreign user
         */
        public function getBlocker() {
                return $this->blocker;
        }

        /**
         * Set the user who implemented (or will implement) this block
         * @param User|string $user Local User object or username string for foreign users
         */
        public function setBlocker( $user ) {
                $this->blocker = $user;
        }

        /**
         * Set the 'BlockID' cookie to this block's ID and expiry time. The cookie's expiry will be
         * the same as the block's, to a maximum of 24 hours.
         *
         * An empty value can also be set, in order to retain the cookie but remove the block ID
         * (e.g. as used in User::getBlockedStatus).
         *
         * @param WebResponse $response The response on which to set the cookie.
         * @param boolean $setEmpty Whether to set the cookie's value to the empty string.
         */
        public function setCookie( WebResponse $response, $setEmpty = false ) {
                // Calculate the default expiry time.
                $maxExpiryTime = wfTimestamp( TS_MW, wfTimestamp() + ( 24 * 60 * 60 ) );

                // Use the Block's expiry time only if it's less than the default.
                $expiryTime = $this->getExpiry();
                if ( $expiryTime === 'infinity' || $expiryTime > $maxExpiryTime ) {
                        $expiryTime = $maxExpiryTime;
                }

                // Set the cookie. Reformat the MediaWiki datetime as a Unix timestamp for the cookie.
                $cookieValue = $setEmpty ? '' : $this->getId();
                $expiryValue = DateTime::createFromFormat( "YmdHis", $expiryTime );
                $response->setCookie( 'BlockID', $cookieValue, $expiryValue->format( "U" ) );
        }

        /**
         * Get the key and parameters for the corresponding error message.
         *
         * @since 1.22
         * @param IContextSource $context
         * @return array
         */
        public function getPermissionsError( IContextSource $context ) {
                $blocker = $this->getBlocker();
                if ( $blocker instanceof User ) { // local user
                        $blockerUserpage = $blocker->getUserPage();
                        $link = "[[{$blockerUserpage->getPrefixedText()}|{$blockerUserpage->getText()}]]";
                } else { // foreign user
                        $link = $blocker;
                }

                $reason = $this->mReason;
                if ( $reason == '' ) {
                        $reason = $context->msg( 'blockednoreason' )->text();
                }

                /* $ip returns who *is* being blocked, $intended contains who was meant to be blocked.
                 * This could be a username, an IP range, or a single IP. */
                $intended = $this->getTarget();

                $systemBlockType = $this->getSystemBlockType();

                $lang = $context->getLanguage();
                return [
                        $systemBlockType !== null
                                ? 'systemblockedtext'
                                : ( $this->mAuto ? 'autoblockedtext' : 'blockedtext' ),
                        $link,
                        $reason,
                        $context->getRequest()->getIP(),
                        $this->getByName(),
                        $systemBlockType !== null ? $systemBlockType : $this->getId(),
                        $lang->formatExpiry( $this->mExpiry ),
                        (string)$intended,
                        $lang->userTimeAndDate( $this->mTimestamp, $context->getUser() ),
                ];
        }
}