Merge "Update searchdisabled message with docs and better link target"

[mediawiki.git] / includes / block / BlockManager.php

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

namespace MediaWiki\Block;

use LogicException;
use MediaWiki\Config\ServiceOptions;
use MediaWiki\HookContainer\HookContainer;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Message\Message;
use MediaWiki\Request\ProxyLookup;
use MediaWiki\Request\WebRequest;
use MediaWiki\Request\WebResponse;
use MediaWiki\User\User;
use MediaWiki\User\UserFactory;
use MediaWiki\User\UserIdentity;
use MediaWiki\User\UserIdentityUtils;
use MWCryptHash;
use Psr\Log\LoggerInterface;
use Wikimedia\IPSet;
use Wikimedia\IPUtils;

/**
 * A service class for checking blocks.
 * To obtain an instance, use MediaWikiServices::getInstance()->getBlockManager().
 *
 * @since 1.34 Refactored from User and Block.
 */
class BlockManager {
        /**
         * @internal For use by ServiceWiring
         */
        public const CONSTRUCTOR_OPTIONS = [
                MainConfigNames::ApplyIpBlocksToXff,
                MainConfigNames::CookieSetOnAutoblock,
                MainConfigNames::CookieSetOnIpBlock,
                MainConfigNames::DnsBlacklistUrls,
                MainConfigNames::EnableDnsBlacklist,
                MainConfigNames::ProxyList,
                MainConfigNames::ProxyWhitelist,
                MainConfigNames::SecretKey,
                MainConfigNames::SoftBlockRanges,
        ];

        private ServiceOptions $options;
        private UserFactory $userFactory;
        private UserIdentityUtils $userIdentityUtils;
        private LoggerInterface $logger;
        private HookRunner $hookRunner;
        private DatabaseBlockStore $blockStore;
        private ProxyLookup $proxyLookup;

        private BlockCache $userBlockCache;
        private BlockCache $createAccountBlockCache;

        public function __construct(
                ServiceOptions $options,
                UserFactory $userFactory,
                UserIdentityUtils $userIdentityUtils,
                LoggerInterface $logger,
                HookContainer $hookContainer,
                DatabaseBlockStore $blockStore,
                ProxyLookup $proxyLookup
        ) {
                $options->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS );
                $this->options = $options;
                $this->userFactory = $userFactory;
                $this->userIdentityUtils = $userIdentityUtils;
                $this->logger = $logger;
                $this->hookRunner = new HookRunner( $hookContainer );
                $this->blockStore = $blockStore;
                $this->proxyLookup = $proxyLookup;

                $this->userBlockCache = new BlockCache;
                $this->createAccountBlockCache = new BlockCache;
        }

        /**
         * Get the blocks that apply to a user. If there is only one, return that, otherwise
         * return a composite block that combines the strictest features of the applicable
         * blocks.
         *
         * Different blocks may be sought, depending on the user and their permissions. The
         * user may be:
         * (1) The global user (and can be affected by IP blocks). The global request object
         * is needed for checking the IP address, the XFF header and the cookies.
         * (2) The global user (and exempt from IP blocks). The global request object is
         * available.
         * (3) Another user (not the global user). No request object is available or needed;
         * just look for a block against the user account.
         *
         * Cases #1 and #2 check whether the global user is blocked in practice; the block
         * may due to their user account being blocked or to an IP address block or cookie
         * block (or multiple of these). Case #3 simply checks whether a user's account is
         * blocked, and does not determine whether the person using that account is affected
         * in practice by any IP address or cookie blocks.
         *
         * @deprecated since 1.42 Use getBlock(), which is the same except that it expects
         *   the caller to do ipblock-exempt permission checking and to set $request to null
         *   if the user is exempt from IP blocks.
         *
         * @param UserIdentity $user
         * @param WebRequest|null $request The global request object if the user is the
         *  global user (cases #1 and #2), otherwise null (case #3). The IP address and
         *  information from the request header are needed to find some types of blocks.
         * @param bool $fromReplica Whether to check the replica DB first.
         *  To improve performance, non-critical checks are done against replica DBs.
         *  Check when actually saving should be done against primary.
         * @param bool $disableIpBlockExemptChecking This is used internally to prevent
         *   a infinite recursion with autopromote. See T270145.
         * @return AbstractBlock|null The most relevant block, or null if there is no block.
         */
        public function getUserBlock(
                UserIdentity $user,
                $request,
                $fromReplica,
                $disableIpBlockExemptChecking = false
        ) {
                wfDeprecated( __METHOD__, '1.42' );
                // If this is the global user, they may be affected by IP blocks (case #1),
                // or they may be exempt (case #2). If affected, look for additional blocks
                // against the IP address and referenced in a cookie.
                $checkIpBlocks = $request &&
                        // Because calling getBlock within Autopromote leads back to here,
                        // thus causing a infinite recursion. We fix this by not checking for
                        // ipblock-exempt when calling getBlock within Autopromote.
                        // See T270145.
                        !$disableIpBlockExemptChecking &&
                        !$this->isIpBlockExempt( $user );

                return $this->getBlock(
                        $user,
                        $checkIpBlocks ? $request : null,
                        $fromReplica
                );
        }

        /**
         * Get the blocks that apply to a user. If there is only one, return that, otherwise
         * return a composite block that combines the strictest features of the applicable
         * blocks.
         *
         * If the user is exempt from IP blocks, the request should be null.
         *
         * @since 1.42
         * @param UserIdentity $user The user performing the action
         * @param WebRequest|null $request The request to use for IP and cookie
         *   blocks, or null to skip checking for such blocks. If the user has the
         *   ipblock-exempt right, the request should be null.
         * @param bool $fromReplica Whether to check the replica DB first.
         *   To improve performance, non-critical checks are done against replica DBs.
         *   Check when actually saving should be done against primary.
         * @return AbstractBlock|null
         */
        public function getBlock(
                UserIdentity $user,
                ?WebRequest $request,
                $fromReplica = true
        ): ?AbstractBlock {
                $fromPrimary = !$fromReplica;
                $ip = null;

                // TODO: normalise the fromPrimary parameter when replication is not configured.
                // Maybe DatabaseBlockStore can tell us about the LoadBalancer configuration.
                $cacheKey = new BlockCacheKey(
                        $request,
                        $user,
                        $fromPrimary
                );
                $block = $this->userBlockCache->get( $cacheKey );
                if ( $block !== null ) {
                        $this->logger->debug( "Block cache hit with key {$cacheKey}" );
                        return $block ?: null;
                }
                $this->logger->debug( "Block cache miss with key {$cacheKey}" );

                if ( $request ) {

                        // Case #1: checking the global user, including IP blocks
                        $ip = $request->getIP();
                        // For soft blocks, i.e. blocks that don't block logged-in users,
                        // temporary users are treated as anon users, and are blocked.
                        $applySoftBlocks = !$this->userIdentityUtils->isNamed( $user );

                        $xff = $request->getHeader( 'X-Forwarded-For' );

                        $blocks = array_merge(
                                $this->blockStore->newListFromTarget( $user, $ip, $fromPrimary ),
                                $this->getSystemIpBlocks( $ip, $applySoftBlocks ),
                                $this->getXffBlocks( $ip, $xff, $applySoftBlocks, $fromPrimary ),
                                $this->getCookieBlock( $user, $request )
                        );
                } else {

                        // Case #2: checking the global user, but they are exempt from IP blocks
                        // and cookie blocks, so we only check for a user account block.
                        // Case #3: checking whether another user's account is blocked.
                        $blocks = $this->blockStore->newListFromTarget( $user, null, $fromPrimary );

                }

                $block = $this->createGetBlockResult( $ip, $blocks );

                $legacyUser = $this->userFactory->newFromUserIdentity( $user );
                $this->hookRunner->onGetUserBlock( clone $legacyUser, $ip, $block );

                $this->userBlockCache->set( $cacheKey, $block ?: false );
                return $block;
        }

        /**
         * Clear the cache of any blocks that refer to the specified user
         */
        public function clearUserCache( UserIdentity $user ) {
                $this->userBlockCache->clearUser( $user );
                $this->createAccountBlockCache->clearUser( $user );
        }

        /**
         * Get the block which applies to a create account action, if there is any
         *
         * @since 1.42
         * @param UserIdentity $user
         * @param WebRequest|null $request The request, or null to omit IP address
         *   and cookie blocks. If the user has the ipblock-exempt right, null
         *   should be passed.
         * @param bool $fromReplica
         * @return AbstractBlock|null
         */
        public function getCreateAccountBlock(
                UserIdentity $user,
                ?WebRequest $request,
                $fromReplica
        ) {
                $key = new BlockCacheKey( $request, $user, $fromReplica );
                $cachedBlock = $this->createAccountBlockCache->get( $key );
                if ( $cachedBlock !== null ) {
                        $this->logger->debug( "Create account block cache hit with key {$key}" );
                        return $cachedBlock ?: null;
                }
                $this->logger->debug( "Create account block cache miss with key {$key}" );

                $applicableBlocks = [];
                $userBlock = $this->getBlock( $user, $request, $fromReplica );
                if ( $userBlock ) {
                        $applicableBlocks = $userBlock->toArray();
                }

                // T15611: if the IP address the user is trying to create an account from is
                // blocked with createaccount disabled, prevent new account creation there even
                // when the user is logged in
                if ( $request ) {
                        $ipBlock = $this->blockStore->newFromTarget(
                                null, $request->getIP()
                        );
                        if ( $ipBlock ) {
                                $applicableBlocks = array_merge( $applicableBlocks, $ipBlock->toArray() );
                        }
                }

                foreach ( $applicableBlocks as $i => $block ) {
                        if ( !$block->appliesToRight( 'createaccount' ) ) {
                                unset( $applicableBlocks[$i] );
                        }
                }
                $result = $this->createGetBlockResult(
                        $request ? $request->getIP() : null,
                        $applicableBlocks
                );
                $this->createAccountBlockCache->set( $key, $result ?: false );
                return $result;
        }

        /**
         * Remove elements of a block which fail a callback test.
         *
         * @since 1.42
         * @param Block|null $block The block, or null to pass in zero blocks.
         * @param callable $callback The callback, which will be called once for
         *   each non-composite component of the block. The only parameter is the
         *   non-composite Block. It should return true, to keep that component,
         *   or false, to remove that component.
         * @return Block|null
         *    - If there are zero remaining elements, null will be returned.
         *    - If there is one remaining element, a DatabaseBlock or some other
         *      non-composite block will be returned.
         *    - If there is more than one remaining element, a CompositeBlock will
         *      be returned.
         */
        public function filter( ?Block $block, $callback ) {
                if ( !$block ) {
                        return null;
                } elseif ( $block instanceof CompositeBlock ) {
                        $blocks = $block->getOriginalBlocks();
                        $originalCount = count( $blocks );
                        foreach ( $blocks as $i => $originalBlock ) {
                                if ( !$callback( $originalBlock ) ) {
                                        unset( $blocks[$i] );
                                }
                        }
                        if ( !$blocks ) {
                                return null;
                        } elseif ( count( $blocks ) === 1 ) {
                                return $blocks[ array_key_first( $blocks ) ];
                        } elseif ( count( $blocks ) === $originalCount ) {
                                return $block;
                        } else {
                                return $block->withOriginalBlocks( array_values( $blocks ) );
                        }
                } elseif ( !$callback( $block ) ) {
                        return null;
                } else {
                        return $block;
                }
        }

        /**
         * Determine if a user is exempt from IP blocks
         * @param UserIdentity $user
         * @return bool
         */
        private function isIpBlockExempt( UserIdentity $user ) {
                return MediaWikiServices::getInstance()->getPermissionManager()
                        ->userHasRight( $user, 'ipblock-exempt' );
        }

        /**
         * @param string|null $ip
         * @param AbstractBlock[] $blocks
         * @return AbstractBlock|null
         */
        private function createGetBlockResult( ?string $ip, array $blocks ): ?AbstractBlock {
                // Filter out any duplicated blocks, e.g. from the cookie
                $blocks = $this->getUniqueBlocks( $blocks );

                if ( count( $blocks ) === 0 ) {
                        return null;
                } elseif ( count( $blocks ) === 1 ) {
                        return $blocks[ 0 ];
                } else {
                        $compositeBlock = CompositeBlock::createFromBlocks( ...$blocks );
                        $compositeBlock->setTarget( $ip );
                        return $compositeBlock;
                }
        }

        /**
         * Get the blocks that apply to an IP address. If there is only one, return that, otherwise
         * return a composite block that combines the strictest features of the applicable blocks.
         *
         * @since 1.38
         * @param string $ip
         * @param bool $fromReplica
         * @return AbstractBlock|null
         */
        public function getIpBlock( string $ip, bool $fromReplica ): ?AbstractBlock {
                if ( !IPUtils::isValid( $ip ) ) {
                        return null;
                }

                $blocks = array_merge(
                        $this->blockStore->newListFromTarget( $ip, $ip, !$fromReplica ),
                        $this->getSystemIpBlocks( $ip, true )
                );

                return $this->createGetBlockResult( $ip, $blocks );
        }

        /**
         * Get the cookie block, if there is one.
         *
         * @param UserIdentity $user
         * @param WebRequest $request
         * @return AbstractBlock[]
         */
        private function getCookieBlock( UserIdentity $user, WebRequest $request ): array {
                $cookieBlock = $this->getBlockFromCookieValue( $user, $request );

                return $cookieBlock instanceof DatabaseBlock ? [ $cookieBlock ] : [];
        }

        /**
         * Get any system blocks against the IP address.
         *
         * @param string $ip
         * @param bool $applySoftBlocks
         * @return AbstractBlock[]
         */
        private function getSystemIpBlocks( string $ip, bool $applySoftBlocks ): array {
                $blocks = [];

                // Proxy blocking
                if ( !in_array( $ip, $this->options->get( MainConfigNames::ProxyWhitelist ) ) ) {
                        // Local list
                        if ( $this->isLocallyBlockedProxy( $ip ) ) {
                                $blocks[] = new SystemBlock( [
                                        'reason' => new Message( 'proxyblockreason' ),
                                        'address' => $ip,
                                        'systemBlock' => 'proxy',
                                ] );
                        } elseif ( $applySoftBlocks && $this->isDnsBlacklisted( $ip ) ) {
                                $blocks[] = new SystemBlock( [
                                        'reason' => new Message( 'sorbsreason' ),
                                        'address' => $ip,
                                        'anonOnly' => true,
                                        'systemBlock' => 'dnsbl',
                                ] );
                        }
                }

                // Soft blocking
                if ( $applySoftBlocks && IPUtils::isInRanges( $ip, $this->options->get( MainConfigNames::SoftBlockRanges ) ) ) {
                        $blocks[] = new SystemBlock( [
                                'address' => $ip,
                                'reason' => new Message( 'softblockrangesreason', [ $ip ] ),
                                'anonOnly' => true,
                                'systemBlock' => 'wgSoftBlockRanges',
                        ] );
                }

                return $blocks;
        }

        /**
         * If `$wgApplyIpBlocksToXff` is truthy and the IP that the user is accessing the wiki from is not in
         * `$wgProxyWhitelist`, then get the blocks that apply to the IP(s) in the X-Forwarded-For HTTP
         * header.
         *
         * @param string $ip
         * @param string $xff
         * @param bool $applySoftBlocks
         * @param bool $fromPrimary
         * @return AbstractBlock[]
         */
        private function getXffBlocks(
                string $ip,
                string $xff,
                bool $applySoftBlocks,
                bool $fromPrimary
        ): array {
                // (T25343) Apply IP blocks to the contents of XFF headers, if enabled
                if ( $this->options->get( MainConfigNames::ApplyIpBlocksToXff )
                        && !in_array( $ip, $this->options->get( MainConfigNames::ProxyWhitelist ) )
                ) {
                        $xff = array_map( 'trim', explode( ',', $xff ) );
                        $xff = array_diff( $xff, [ $ip ] );
                        $xffblocks = $this->getBlocksForIPList( $xff, $applySoftBlocks, $fromPrimary );

                        // (T285159) Exclude autoblocks from XFF headers to prevent spoofed
                        // headers uncovering the IPs of autoblocked users
                        $xffblocks = array_filter( $xffblocks, static function ( $block ) {
                                return $block->getType() !== Block::TYPE_AUTO;
                        } );

                        return $xffblocks;
                }

                return [];
        }

        /**
         * Get all blocks that match any IP from an array of IP addresses
         *
         * @internal Public to support deprecated method in DatabaseBlock
         *
         * @param array $ipChain List of IPs (strings), usually retrieved from the
         *     X-Forwarded-For header of the request
         * @param bool $applySoftBlocks Include soft blocks (anonymous-only blocks). These
         *     should only block anonymous and temporary users.
         * @param bool $fromPrimary Whether to query the primary or replica DB
         * @return DatabaseBlock[]
         */
        public function getBlocksForIPList( array $ipChain, bool $applySoftBlocks, bool $fromPrimary ) {
                if ( $ipChain === [] ) {
                        return [];
                }

                $ips = [];
                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 ( !IPUtils::isValid( $ipaddr ) ) {
                                continue;
                        }
                        // Don't check trusted IPs (includes local CDNs which will be in every request)
                        if ( $this->proxyLookup->isTrustedProxy( $ipaddr ) ) {
                                continue;
                        }
                        $ips[] = $ipaddr;
                }
                return $this->blockStore->newListFromIPs( $ips, $applySoftBlocks, $fromPrimary );
        }

        /**
         * Given a list of blocks, return a list of unique blocks.
         *
         * This usually means that each block has a unique ID. For a block with ID null,
         * if it's an autoblock, it will be filtered out if the parent block is present;
         * if not, it is assumed to be a unique system block, and kept.
         *
         * @param AbstractBlock[] $blocks
         * @return AbstractBlock[]
         */
        private function getUniqueBlocks( array $blocks ) {
                $systemBlocks = [];
                $databaseBlocks = [];

                foreach ( $blocks as $block ) {
                        if ( $block instanceof SystemBlock ) {
                                $systemBlocks[] = $block;
                        } elseif ( $block->getType() === DatabaseBlock::TYPE_AUTO && $block instanceof DatabaseBlock ) {
                                if ( !isset( $databaseBlocks[$block->getParentBlockId()] ) ) {
                                        $databaseBlocks[$block->getParentBlockId()] = $block;
                                }
                        } else {
                                // @phan-suppress-next-line PhanTypeMismatchDimAssignment getId is not null here
                                $databaseBlocks[$block->getId()] = $block;
                        }
                }

                return array_values( array_merge( $systemBlocks, $databaseBlocks ) );
        }

        /**
         * Try to load a block from an ID given in a cookie value.
         *
         * If the block is invalid, doesn't exist, or the cookie value is malformed, no
         * block will be loaded. In these cases the cookie will either (1) be replaced
         * with a valid cookie or (2) removed, next time trackBlockWithCookie is called.
         *
         * @param UserIdentity $user
         * @param WebRequest $request
         * @return DatabaseBlock|false The block object, or false if none could be loaded.
         */
        private function getBlockFromCookieValue(
                UserIdentity $user,
                WebRequest $request
        ) {
                $cookieValue = $request->getCookie( 'BlockID' );
                if ( $cookieValue === null ) {
                        return false;
                }

                $blockCookieId = $this->getIdFromCookieValue( $cookieValue );
                if ( $blockCookieId !== null ) {
                        $block = $this->blockStore->newFromID( $blockCookieId );
                        if (
                                $block instanceof DatabaseBlock &&
                                $this->shouldApplyCookieBlock( $block, !$user->isRegistered() )
                        ) {
                                return $block;
                        }
                }

                return false;
        }

        /**
         * Check if the block loaded from the cookie should be applied.
         *
         * @param DatabaseBlock $block
         * @param bool $isAnon The user is logged out
         * @return bool The block should be applied
         */
        private function shouldApplyCookieBlock( DatabaseBlock $block, $isAnon ) {
                if ( !$block->isExpired() ) {
                        switch ( $block->getType() ) {
                                case DatabaseBlock::TYPE_IP:
                                case DatabaseBlock::TYPE_RANGE:
                                        // If block is type IP or IP range, load only
                                        // if user is not logged in (T152462)
                                        return $isAnon &&
                                                $this->options->get( MainConfigNames::CookieSetOnIpBlock );
                                case DatabaseBlock::TYPE_USER:
                                        return $block->isAutoblocking() &&
                                                $this->options->get( MainConfigNames::CookieSetOnAutoblock );
                                default:
                                        return false;
                        }
                }
                return false;
        }

        /**
         * Check if an IP address is in the local proxy list
         *
         * @param string $ip
         * @return bool
         */
        private function isLocallyBlockedProxy( $ip ) {
                $proxyList = $this->options->get( MainConfigNames::ProxyList );
                if ( !$proxyList ) {
                        return false;
                }

                if ( !is_array( $proxyList ) ) {
                        // Load values from the specified file
                        $proxyList = array_map( 'trim', file( $proxyList ) );
                }

                $proxyListIPSet = new IPSet( $proxyList );
                return $proxyListIPSet->match( $ip );
        }

        /**
         * Whether the given IP is in a DNS blacklist.
         *
         * @param string $ip IP to check
         * @param bool $checkAllowed Whether to check $wgProxyWhitelist first
         * @return bool True if blacklisted.
         */
        public function isDnsBlacklisted( $ip, $checkAllowed = false ) {
                if ( !$this->options->get( MainConfigNames::EnableDnsBlacklist ) ||
                        ( $checkAllowed && in_array( $ip, $this->options->get( MainConfigNames::ProxyWhitelist ) ) )
                ) {
                        return false;
                }

                return $this->inDnsBlacklist( $ip, $this->options->get( MainConfigNames::DnsBlacklistUrls ) );
        }

        /**
         * Whether the given IP is in a given DNS blacklist.
         *
         * @param string $ip IP to check
         * @param string[] $bases URL of the DNS blacklist
         * @return bool True if blacklisted.
         */
        private function inDnsBlacklist( $ip, array $bases ) {
                $found = false;
                // @todo FIXME: IPv6 ???  (https://bugs.php.net/bug.php?id=33170)
                if ( IPUtils::isIPv4( $ip ) ) {
                        // Reverse IP, T23255
                        $ipReversed = implode( '.', array_reverse( explode( '.', $ip ) ) );

                        foreach ( $bases as $base ) {
                                // Make hostname
                                // If we have an access key, use that too (ProjectHoneypot, etc.)
                                $basename = $base;
                                if ( is_array( $base ) ) {
                                        if ( count( $base ) >= 2 ) {
                                                // Access key is 1, base URL is 0
                                                $hostname = "{$base[1]}.$ipReversed.{$base[0]}";
                                        } else {
                                                $hostname = "$ipReversed.{$base[0]}";
                                        }
                                        $basename = $base[0];
                                } else {
                                        $hostname = "$ipReversed.$base";
                                }

                                // Send query
                                $ipList = $this->checkHost( $hostname );

                                if ( $ipList ) {
                                        $this->logger->info(
                                                'Hostname {hostname} is {ipList}, it\'s a proxy says {basename}!',
                                                [
                                                        'hostname' => $hostname,
                                                        'ipList' => $ipList[0],
                                                        'basename' => $basename,
                                                ]
                                        );
                                        $found = true;
                                        break;
                                }

                                $this->logger->debug( "Requested $hostname, not found in $basename." );
                        }
                }

                return $found;
        }

        /**
         * Wrapper for mocking in tests.
         *
         * @param string $hostname DNSBL query
         * @return string[]|false IPv4 array, or false if the IP is not blacklisted
         */
        protected function checkHost( $hostname ) {
                return gethostbynamel( $hostname );
        }

        /**
         * Set the 'BlockID' cookie depending on block type and user authentication status.
         *
         * If a block cookie is already set, this will check the block that the cookie references
         * and do the following:
         *  - If the block is a valid block that should be applied, do nothing and return early.
         *    This ensures that the cookie's expiry time is based on the time of the first page
         *    load or attempt. (See discussion on T233595.)
         *  - If the block is invalid (e.g. has expired), clear the cookie and continue to check
         *    whether there is another block that should be tracked.
         *  - If the block is a valid block, but should not be tracked by a cookie, clear the
         *    cookie and continue to check whether there is another block that should be tracked.
         *
         * Must be called after the User object is loaded, and before headers are sent.
         *
         * @since 1.34
         * @param User $user
         * @param WebResponse $response The response on which to set the cookie.
         */
        public function trackBlockWithCookie( User $user, WebResponse $response ) {
                if ( !$this->options->get( MainConfigNames::CookieSetOnIpBlock ) &&
                        !$this->options->get( MainConfigNames::CookieSetOnAutoblock ) ) {
                        // Cookie blocks are disabled, return early to prevent executing unnecessary logic.
                        return;
                }

                $request = $user->getRequest();

                if ( $request->getCookie( 'BlockID' ) !== null ) {
                        $cookieBlock = $this->getBlockFromCookieValue( $user, $request );
                        if ( $cookieBlock && $this->shouldApplyCookieBlock( $cookieBlock, $user->isAnon() ) ) {
                                return;
                        }
                        // The block pointed to by the cookie is invalid or should not be tracked.
                        $this->clearBlockCookie( $response );
                }

                if ( !$user->isSafeToLoad() ) {
                        // Prevent a circular dependency by not allowing this method to be called
                        // before or while the user is being loaded.
                        // E.g. User > BlockManager > Block > Message > getLanguage > User.
                        // See also T180050 and T226777.
                        throw new LogicException( __METHOD__ . ' requires a loaded User object' );
                }
                if ( $response->headersSent() ) {
                        throw new LogicException( __METHOD__ . ' must be called pre-send' );
                }

                $block = $user->getBlock();
                $isAnon = $user->isAnon();

                if ( $block ) {
                        foreach ( $block->toArray() as $originalBlock ) {
                                // TODO: Improve on simply tracking the first trackable block (T225654)
                                if ( $originalBlock instanceof DatabaseBlock
                                        && $this->shouldTrackBlockWithCookie( $originalBlock, $isAnon )
                                ) {
                                        $this->setBlockCookie( $originalBlock, $response );
                                        return;
                                }
                        }
                }
        }

        /**
         * 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.
         *
         * @since 1.34
         * @param DatabaseBlock $block
         * @param WebResponse $response The response on which to set the cookie.
         */
        private function setBlockCookie( DatabaseBlock $block, WebResponse $response ) {
                // Calculate the default expiry time.
                $maxExpiryTime = wfTimestamp( TS_MW, (int)wfTimestamp() + ( 24 * 60 * 60 ) );

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

                // Set the cookie
                $expiryValue = (int)wfTimestamp( TS_UNIX, $expiryTime );
                $cookieOptions = [ 'httpOnly' => false ];
                $cookieValue = $this->getCookieValue( $block );
                $response->setCookie( 'BlockID', $cookieValue, $expiryValue, $cookieOptions );
        }

        /**
         * Check if the block should be tracked with a cookie.
         *
         * @param DatabaseBlock $block
         * @param bool $isAnon The user is logged out
         * @return bool The block should be tracked with a cookie
         */
        private function shouldTrackBlockWithCookie( DatabaseBlock $block, $isAnon ) {
                switch ( $block->getType() ) {
                        case DatabaseBlock::TYPE_IP:
                        case DatabaseBlock::TYPE_RANGE:
                                return $isAnon && $this->options->get( MainConfigNames::CookieSetOnIpBlock );
                        case DatabaseBlock::TYPE_USER:
                                return !$isAnon &&
                                        $this->options->get( MainConfigNames::CookieSetOnAutoblock ) &&
                                        $block->isAutoblocking();
                        default:
                                return false;
                }
        }

        /**
         * Unset the 'BlockID' cookie.
         *
         * @since 1.34
         * @param WebResponse $response
         */
        public static function clearBlockCookie( WebResponse $response ) {
                $response->clearCookie( 'BlockID', [ 'httpOnly' => false ] );
        }

        /**
         * Get the stored ID from the 'BlockID' cookie. The cookie's value is usually a combination of
         * the ID and a HMAC (see self::getCookieValue), but will sometimes only be the ID.
         *
         * @since 1.34
         * @param string $cookieValue The string in which to find the ID.
         * @return int|null The block ID, or null if the HMAC is present and invalid.
         */
        private function getIdFromCookieValue( $cookieValue ) {
                // The cookie value must start with a number
                if ( !is_numeric( substr( $cookieValue, 0, 1 ) ) ) {
                        return null;
                }

                // Extract the ID prefix from the cookie value (may be the whole value, if no bang found).
                $bangPos = strpos( $cookieValue, '!' );
                $id = ( $bangPos === false ) ? $cookieValue : substr( $cookieValue, 0, $bangPos );
                if ( !$this->options->get( MainConfigNames::SecretKey ) ) {
                        // If there's no secret key, just use the ID as given.
                        return (int)$id;
                }
                $storedHmac = substr( $cookieValue, $bangPos + 1 );
                $calculatedHmac = MWCryptHash::hmac( $id, $this->options->get( MainConfigNames::SecretKey ), false );
                if ( $calculatedHmac === $storedHmac ) {
                        return (int)$id;
                } else {
                        return null;
                }
        }

        /**
         * Get the BlockID cookie's value for this block. This is usually the block ID concatenated
         * with an HMAC in order to avoid spoofing (T152951), but if wgSecretKey is not set will just
         * be the block ID.
         *
         * @since 1.34
         * @param DatabaseBlock $block
         * @return string The block ID, probably concatenated with "!" and the HMAC.
         */
        private function getCookieValue( DatabaseBlock $block ) {
                $id = (string)$block->getId();
                if ( !$this->options->get( MainConfigNames::SecretKey ) ) {
                        // If there's no secret key, don't append a HMAC.
                        return $id;
                }
                $hmac = MWCryptHash::hmac( $id, $this->options->get( MainConfigNames::SecretKey ), false );
                return $id . '!' . $hmac;
        }
}