Block.php

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<?php
class Block {
        /* public*/ var $mReason, $mTimestamp, $mAuto, $mExpiry, $mHideName;

        protected
                $mId,
                $mFromMaster,

                $mBlockEmail,
                $mDisableUsertalk,
                $mCreateAccount,
                $mParentBlockId;

        protected $target;

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

        protected $type;

        protected $blocker;

        protected $isHardblock = true;

        protected $isAutoblocking = true;

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

        function __construct( $address = '', $user = 0, $by = 0, $reason = '',
                $timestamp = 0, $auto = 0, $expiry = '', $anonOnly = 0, $createAccount = 0, $enableAutoblock = 0,
                $hideName = 0, $blockEmail = 0, $allowUsertalk = 0, $byText = '' )
        {
                if( $timestamp === 0 ) {
                        $timestamp = wfTimestampNow();
                }

                if( count( func_get_args() ) > 0 ) {
                        # Soon... :D
                        # wfDeprecated( __METHOD__ . " with arguments" );
                }

                $this->setTarget( $address );
                if ( $this->target instanceof User && $user ) {
                        $this->forcedTargetID = $user; // needed for foreign users
                }
                if ( $by ) { // local user
                        $this->setBlocker( User::newFromID( $by ) );
                } else { // foreign user
                        $this->setBlocker( $byText );
                }
                $this->mReason = $reason;
                $this->mTimestamp = wfTimestamp( TS_MW, $timestamp );
                $this->mAuto = $auto;
                $this->isHardblock( !$anonOnly );
                $this->prevents( 'createaccount', $createAccount );
                if ( $expiry == 'infinity' || $expiry == wfGetDB( DB_SLAVE )->getInfinity() ) {
                        $this->mExpiry = 'infinity';
                } else {
                        $this->mExpiry = wfTimestamp( TS_MW, $expiry );
                }
                $this->isAutoblocking( $enableAutoblock );
                $this->mHideName = $hideName;
                $this->prevents( 'sendemail', $blockEmail );
                $this->prevents( 'editownusertalk', !$allowUsertalk );

                $this->mFromMaster = false;
        }

        public static function newFromDB( $address, $user = 0 ) {
                wfDeprecated( __METHOD__, '1.18' );
                return self::newFromTarget( User::whoIs( $user ), $address );
        }

        public static function newFromID( $id ) {
                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->selectRow(
                        'ipblocks',
                        self::selectFields(),
                        array( 'ipb_id' => $id ),
                        __METHOD__
                );
                if ( $res ) {
                        return self::newFromRow( $res );
                } else {
                        return null;
                }
        }

        public static function selectFields() {
                return array(
                        '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',
                );
        }

        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
                );
        }

        public function clear() {
                wfDeprecated( __METHOD__, '1.18' );
                # Noop
        }

        public function load( $address = '', $user = 0 ) {
                wfDeprecated( __METHOD__, '1.18' );
                if( $user ) {
                        $username = User::whoIs( $user );
                        $block = self::newFromTarget( $username, $address );
                } else {
                        $block = self::newFromTarget( null, $address );
                }

                if( $block instanceof Block ) {
                        # This is mildly evil, but hey, it's B/C :D
                        foreach( $block as $variable => $value ) {
                                $this->$variable = $value;
                        }
                        return true;
                } else {
                        return false;
                }
        }

        protected function newLoad( $vagueTarget = null ) {
                $db = wfGetDB( $this->mFromMaster ? DB_MASTER : DB_SLAVE );

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

                # 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->deleteIfExpired() ) {
                                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 = wfBaseconvert( $block->getRangeEnd(), 16, 10 );
                                $start = wfBaseconvert( $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;
                }
        }

        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_SLAVE );
                $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(
                        array(
                                "ipb_range_start $like",
                                "ipb_range_start <= $safeStart",
                                "ipb_range_end >= $safeEnd",
                        ),
                        LIST_AND
                );
        }

        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 ) );
                }
        }

        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 = $row->ipb_id;
                $this->mParentBlockId = $row->ipb_parent_block_id;

                // I wish I didn't have to do this
                $db = wfGetDB( DB_SLAVE );
                if ( $row->ipb_expiry == $db->getInfinity() ) {
                        $this->mExpiry = 'infinity';
                } else {
                        $this->mExpiry = wfTimestamp( TS_MW, $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 );
        }

        public static function newFromRow( $row ) {
                $block = new Block;
                $block->initFromRow( $row );
                return $block;
        }

        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', array( 'ipb_parent_block_id' => $this->getId() ), __METHOD__ );
                $dbw->delete( 'ipblocks', array( 'ipb_id' => $this->getId() ), __METHOD__ );

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

        public function insert( $dbw = null ) {
                wfDebug( "Block::insert; timestamp {$this->mTimestamp}\n" );

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

                # Don't collide with expired blocks
                Block::purgeExpired();

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

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

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

                return false;
        }

        public function update() {
                wfDebug( "Block::update; timestamp {$this->mTimestamp}\n" );
                $dbw = wfGetDB( DB_MASTER );

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

                return $dbw->affectedRows();
        }

        protected function getDatabaseArray( $db = null ) {
                if( !$db ) {
                        $db = wfGetDB( DB_SLAVE );
                }
                $expiry = $db->encodeExpiry( $this->mExpiry );

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

                $a = array(
                        'ipb_address'          => (string)$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;
        }

        protected function doRetroactiveAutoblock() {
                $blockIds = array();
                # 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 = wfRunHooks(
                                'PerformRetroactiveAutoblock', array( $this, &$blockIds ) );

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

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

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

                $res = $dbr->select( 'recentchanges', array( '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;
                                }
                        }
                }
        }

        public static function isWhitelistedFromAutoblocks( $ip ) {
                global $wgMemc;

                // Try to get the autoblock_whitelist from the cache, as it's faster
                // than getting the msg raw and explode()'ing it.
                $key = wfMemcKey( 'ipb', 'autoblock', 'whitelist' );
                $lines = $wgMemc->get( $key );
                if ( !$lines ) {
                        $lines = explode( "\n", wfMessage( 'autoblock_whitelist' )->inContentLanguage()->plain() );
                        $wgMemc->set( $key, $lines, 3600 * 24 );
                }

                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;
        }

        public function doAutoblock( $autoblockIP ) {
                # If autoblocks are disabled, go away.
                if ( !$this->isAutoblocking() ) {
                        return false;
                }

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

                # Allow hooks to cancel the autoblock.
                if ( !wfRunHooks( 'AbortAutoblock', array( $autoblockIP, &$this ) ) ) {
                        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;
        }

        public function deleteIfExpired() {
                wfProfileIn( __METHOD__ );

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

                wfProfileOut( __METHOD__ );
                return $retVal;
        }

        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;
                }
        }

        public function isValid() {
                return $this->getTarget() != null;
        }

        public function updateTimestamp() {
                if ( $this->mAuto ) {
                        $this->mTimestamp = wfTimestamp();
                        $this->mExpiry = Block::getAutoblockExpiry( $this->mTimestamp );

                        $dbw = wfGetDB( DB_MASTER );
                        $dbw->update( 'ipblocks',
                                array( /* SET */
                                        'ipb_timestamp' => $dbw->timestamp( $this->mTimestamp ),
                                        'ipb_expiry' => $dbw->timestamp( $this->mExpiry ),
                                ),
                                array( /* WHERE */
                                        'ipb_address' => (string)$this->getTarget()
                                ),
                                __METHOD__
                        );
                }
        }

        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" );
                }
        }

        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" );
                }
        }

        public function getBy() {
                $blocker = $this->getBlocker();
                return ( $blocker instanceof User )
                        ? $blocker->getId()
                        : 0;
        }

        public function getByName() {
                $blocker = $this->getBlocker();
                return ( $blocker instanceof User )
                        ? $blocker->getName()
                        : (string)$blocker; // username
        }

        public function getId() {
                return $this->mId;
        }

        public function forUpdate( $x = null ) {
                wfDeprecated( __METHOD__, '1.18' );
                # noop
        }

        public function fromMaster( $x = null ) {
                return wfSetVar( $this->mFromMaster, $x );
        }

        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;
        }

        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;
        }

        public function prevents( $action, $x = null ) {
                switch( $action ) {
                        case 'edit':
                                # For now... <evil laugh>
                                return true;

                        case 'createaccount':
                                return wfSetVar( $this->mCreateAccount, $x );

                        case 'sendemail':
                                return wfSetVar( $this->mBlockEmail, $x );

                        case 'editownusertalk':
                                return wfSetVar( $this->mDisableUsertalk, $x );

                        default:
                                return null;
                }
        }

        public function getRedactedName() {
                if ( $this->mAuto ) {
                        return Html::rawElement(
                                'span',
                                array( 'class' => 'mw-autoblockid' ),
                                wfMessage( 'autoblockid', $this->mId )
                        );
                } else {
                        return htmlspecialchars( $this->getTarget() );
                }
        }

        public static function encodeExpiry( $expiry, $db ) {
                wfDeprecated( __METHOD__, '1.18' );
                return $db->encodeExpiry( $expiry );
        }

        public static function decodeExpiry( $expiry, $timestampType = TS_MW ) {
                wfDeprecated( __METHOD__, '1.18' );
                global $wgContLang;
                return $wgContLang->formatExpiry( $expiry, $timestampType );
        }

        public static function getAutoblockExpiry( $timestamp ) {
                global $wgAutoblockExpiry;

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

        public static function normaliseRange( $range ) {
                wfDeprecated( __METHOD__, '1.18' );
                return IP::sanitizeRange( $range );
        }

        public static function purgeExpired() {
                if ( !wfReadOnly() ) {
                        $dbw = wfGetDB( DB_MASTER );
                        $dbw->delete( 'ipblocks',
                                array( 'ipb_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ), __METHOD__ );
                }
        }

        public static function infinity() {
                wfDeprecated( __METHOD__, '1.18' );
                return wfGetDB( DB_SLAVE )->getInfinity();
        }

        public static function parseExpiryInput( $expiry ) {
                wfDeprecated( __METHOD__, '1.18' );
                return SpecialBlock::parseExpiryInput( $expiry );
        }

        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, array( 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;
        }

        public static function parseTarget( $target ) {
                # We may have been through this before
                if( $target instanceof User ) {
                        if( IP::isValid( $target->getName() ) ) {
                                return array( $target, self::TYPE_IP );
                        } else {
                                return array( $target, self::TYPE_USER );
                        }
                } elseif( $target === null ) {
                        return array( 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 array(
                                User::newFromName( IP::sanitizeIP( $target ), false ),
                                Block::TYPE_IP
                        );

                } elseif ( IP::isValidBlock( $target ) ) {
                        # Can't create a User from an IP range
                        return array( 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
                        $parts = explode( '/', $target );
                        $target = $parts[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 array( $userObj, Block::TYPE_USER );

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

                } else {
                        # WTF?
                        return array( null, null );
                }
        }

        public function getType() {
                return $this->mAuto
                        ? self::TYPE_AUTO
                        : $this->type;
        }

        public function getTargetAndType() {
                return array( $this->getTarget(), $this->getType() );
        }

        public function getTarget() {
                return $this->target;
        }

        public function getExpiry() {
                return $this->mExpiry;
        }

        public function setTarget( $target ) {
                list( $this->target, $this->type ) = self::parseTarget( $target );
        }

        public function getBlocker() {
                return $this->blocker;
        }

        public function setBlocker( $user ) {
                $this->blocker = $user;
        }
}