310 lines
10 KiB
PHP
310 lines
10 KiB
PHP
<?php
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namespace MaxMind\Db;
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use MaxMind\Db\Reader\Decoder;
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use MaxMind\Db\Reader\InvalidDatabaseException;
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use MaxMind\Db\Reader\Metadata;
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use MaxMind\Db\Reader\Util;
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/**
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* Instances of this class provide a reader for the MaxMind DB format. IP
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* addresses can be looked up using the <code>get</code> method.
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*/
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class Reader
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{
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private static $DATA_SECTION_SEPARATOR_SIZE = 16;
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private static $METADATA_START_MARKER = "\xAB\xCD\xEFMaxMind.com";
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private static $METADATA_START_MARKER_LENGTH = 14;
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private static $METADATA_MAX_SIZE = 131072; // 128 * 1024 = 128KB
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private $decoder;
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private $fileHandle;
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private $fileSize;
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private $ipV4Start;
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private $metadata;
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/**
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* Constructs a Reader for the MaxMind DB format. The file passed to it must
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* be a valid MaxMind DB file such as a GeoIp2 database file.
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*
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* @param string $database
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* the MaxMind DB file to use
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*
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* @throws \InvalidArgumentException for invalid database path or unknown arguments
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* @throws \MaxMind\Db\Reader\InvalidDatabaseException
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* if the database is invalid or there is an error reading
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* from it
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*/
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public function __construct($database)
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{
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if (func_num_args() !== 1) {
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throw new \InvalidArgumentException(
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'The constructor takes exactly one argument.'
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);
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}
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if (!is_readable($database)) {
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throw new \InvalidArgumentException(
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"The file \"$database\" does not exist or is not readable."
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);
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}
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$this->fileHandle = @fopen($database, 'rb');
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if ($this->fileHandle === false) {
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throw new \InvalidArgumentException(
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"Error opening \"$database\"."
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);
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}
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$this->fileSize = @filesize($database);
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if ($this->fileSize === false) {
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throw new \UnexpectedValueException(
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"Error determining the size of \"$database\"."
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);
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}
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$start = $this->findMetadataStart($database);
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$metadataDecoder = new Decoder($this->fileHandle, $start);
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list($metadataArray) = $metadataDecoder->decode($start);
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$this->metadata = new Metadata($metadataArray);
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$this->decoder = new Decoder(
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$this->fileHandle,
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$this->metadata->searchTreeSize + self::$DATA_SECTION_SEPARATOR_SIZE
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);
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}
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/**
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* Looks up the <code>address</code> in the MaxMind DB.
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*
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* @param string $ipAddress
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* the IP address to look up
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*
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* @throws \BadMethodCallException if this method is called on a closed database
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* @throws \InvalidArgumentException if something other than a single IP address is passed to the method
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* @throws InvalidDatabaseException
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* if the database is invalid or there is an error reading
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* from it
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*
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* @return array the record for the IP address
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*/
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public function get($ipAddress)
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{
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if (func_num_args() !== 1) {
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throw new \InvalidArgumentException(
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'Method takes exactly one argument.'
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);
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}
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if (!is_resource($this->fileHandle)) {
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throw new \BadMethodCallException(
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'Attempt to read from a closed MaxMind DB.'
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);
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}
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if (!filter_var($ipAddress, FILTER_VALIDATE_IP)) {
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throw new \InvalidArgumentException(
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"The value \"$ipAddress\" is not a valid IP address."
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);
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}
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if ($this->metadata->ipVersion === 4 && strrpos($ipAddress, ':')) {
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throw new \InvalidArgumentException(
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"Error looking up $ipAddress. You attempted to look up an"
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. ' IPv6 address in an IPv4-only database.'
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);
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}
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$pointer = $this->findAddressInTree($ipAddress);
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if ($pointer === 0) {
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return null;
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}
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return $this->resolveDataPointer($pointer);
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}
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private function findAddressInTree($ipAddress)
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{
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// XXX - could simplify. Done as a byte array to ease porting
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$rawAddress = array_merge(unpack('C*', inet_pton($ipAddress)));
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$bitCount = count($rawAddress) * 8;
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// The first node of the tree is always node 0, at the beginning of the
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// value
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$node = $this->startNode($bitCount);
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for ($i = 0; $i < $bitCount; $i++) {
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if ($node >= $this->metadata->nodeCount) {
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break;
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}
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$tempBit = 0xFF & $rawAddress[$i >> 3];
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$bit = 1 & ($tempBit >> 7 - ($i % 8));
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$node = $this->readNode($node, $bit);
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}
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if ($node === $this->metadata->nodeCount) {
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// Record is empty
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return 0;
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} elseif ($node > $this->metadata->nodeCount) {
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// Record is a data pointer
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return $node;
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}
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throw new InvalidDatabaseException('Something bad happened');
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}
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private function startNode($length)
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{
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// Check if we are looking up an IPv4 address in an IPv6 tree. If this
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// is the case, we can skip over the first 96 nodes.
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if ($this->metadata->ipVersion === 6 && $length === 32) {
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return $this->ipV4StartNode();
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}
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// The first node of the tree is always node 0, at the beginning of the
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// value
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return 0;
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}
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private function ipV4StartNode()
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{
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// This is a defensive check. There is no reason to call this when you
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// have an IPv4 tree.
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if ($this->metadata->ipVersion === 4) {
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return 0;
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}
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if ($this->ipV4Start) {
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return $this->ipV4Start;
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}
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$node = 0;
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for ($i = 0; $i < 96 && $node < $this->metadata->nodeCount; $i++) {
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$node = $this->readNode($node, 0);
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}
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$this->ipV4Start = $node;
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return $node;
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}
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private function readNode($nodeNumber, $index)
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{
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$baseOffset = $nodeNumber * $this->metadata->nodeByteSize;
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// XXX - probably could condense this.
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switch ($this->metadata->recordSize) {
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case 24:
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$bytes = Util::read($this->fileHandle, $baseOffset + $index * 3, 3);
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list(, $node) = unpack('N', "\x00" . $bytes);
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return $node;
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case 28:
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$middleByte = Util::read($this->fileHandle, $baseOffset + 3, 1);
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list(, $middle) = unpack('C', $middleByte);
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if ($index === 0) {
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$middle = (0xF0 & $middle) >> 4;
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} else {
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$middle = 0x0F & $middle;
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}
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$bytes = Util::read($this->fileHandle, $baseOffset + $index * 4, 3);
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list(, $node) = unpack('N', chr($middle) . $bytes);
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return $node;
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case 32:
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$bytes = Util::read($this->fileHandle, $baseOffset + $index * 4, 4);
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list(, $node) = unpack('N', $bytes);
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return $node;
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default:
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throw new InvalidDatabaseException(
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'Unknown record size: '
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. $this->metadata->recordSize
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);
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}
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}
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private function resolveDataPointer($pointer)
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{
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$resolved = $pointer - $this->metadata->nodeCount
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+ $this->metadata->searchTreeSize;
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if ($resolved > $this->fileSize) {
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throw new InvalidDatabaseException(
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"The MaxMind DB file's search tree is corrupt"
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);
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}
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list($data) = $this->decoder->decode($resolved);
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return $data;
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}
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/*
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* This is an extremely naive but reasonably readable implementation. There
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* are much faster algorithms (e.g., Boyer-Moore) for this if speed is ever
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* an issue, but I suspect it won't be.
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*/
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private function findMetadataStart($filename)
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{
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$handle = $this->fileHandle;
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$fstat = fstat($handle);
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$fileSize = $fstat['size'];
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$marker = self::$METADATA_START_MARKER;
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$markerLength = self::$METADATA_START_MARKER_LENGTH;
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$metadataMaxLengthExcludingMarker
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= min(self::$METADATA_MAX_SIZE, $fileSize) - $markerLength;
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for ($i = 0; $i <= $metadataMaxLengthExcludingMarker; $i++) {
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for ($j = 0; $j < $markerLength; $j++) {
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fseek($handle, $fileSize - $i - $j - 1);
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$matchBit = fgetc($handle);
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if ($matchBit !== $marker[$markerLength - $j - 1]) {
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continue 2;
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}
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}
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return $fileSize - $i;
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}
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throw new InvalidDatabaseException(
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"Error opening database file ($filename). " .
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'Is this a valid MaxMind DB file?'
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);
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}
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/**
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* @throws \InvalidArgumentException if arguments are passed to the method
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* @throws \BadMethodCallException if the database has been closed
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*
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* @return Metadata object for the database
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*/
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public function metadata()
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{
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if (func_num_args()) {
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throw new \InvalidArgumentException(
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'Method takes no arguments.'
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);
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}
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// Not technically required, but this makes it consistent with
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// C extension and it allows us to change our implementation later.
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if (!is_resource($this->fileHandle)) {
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throw new \BadMethodCallException(
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'Attempt to read from a closed MaxMind DB.'
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);
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}
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return $this->metadata;
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}
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/**
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* Closes the MaxMind DB and returns resources to the system.
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*
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* @throws \Exception
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* if an I/O error occurs
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*/
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public function close()
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{
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if (!is_resource($this->fileHandle)) {
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throw new \BadMethodCallException(
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'Attempt to close a closed MaxMind DB.'
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);
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}
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fclose($this->fileHandle);
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}
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}
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