373 lines
11 KiB
PHP
373 lines
11 KiB
PHP
<?php
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declare(strict_types=1);
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namespace MaxMind\Db;
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use ArgumentCountError;
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use BadMethodCallException;
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use Exception;
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use InvalidArgumentException;
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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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use UnexpectedValueException;
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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 get method.
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*/
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class Reader
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{
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/**
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* @var int
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*/
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private static $DATA_SECTION_SEPARATOR_SIZE = 16;
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/**
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* @var string
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*/
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private static $METADATA_START_MARKER = "\xAB\xCD\xEFMaxMind.com";
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/**
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* @var int
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*/
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private static $METADATA_START_MARKER_LENGTH = 14;
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/**
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* @var int
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*/
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private static $METADATA_MAX_SIZE = 131072; // 128 * 1024 = 128KiB
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/**
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* @var Decoder
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*/
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private $decoder;
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/**
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* @var resource
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*/
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private $fileHandle;
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/**
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* @var int
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*/
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private $fileSize;
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/**
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* @var int
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*/
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private $ipV4Start;
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/**
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* @var Metadata
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*/
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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 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(string $database)
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{
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if (\func_num_args() !== 1) {
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throw new ArgumentCountError(
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sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())
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);
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}
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$fileHandle = @fopen($database, 'rb');
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if ($fileHandle === false) {
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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 = $fileHandle;
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$fileSize = @filesize($database);
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if ($fileSize === false) {
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throw new UnexpectedValueException(
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"Error determining the size of \"$database\"."
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);
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}
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$this->fileSize = $fileSize;
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$start = $this->findMetadataStart($database);
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$metadataDecoder = new Decoder($this->fileHandle, $start);
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[$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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$this->ipV4Start = $this->ipV4StartNode();
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}
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/**
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* Retrieves the record for the IP address.
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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 mixed the record for the IP address
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*/
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public function get(string $ipAddress)
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{
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if (\func_num_args() !== 1) {
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throw new ArgumentCountError(
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sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())
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);
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}
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[$record] = $this->getWithPrefixLen($ipAddress);
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return $record;
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}
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/**
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* Retrieves the record for the IP address and its associated network prefix length.
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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 an array where the first element is the record and the
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* second the network prefix length for the record
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*/
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public function getWithPrefixLen(string $ipAddress): array
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{
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if (\func_num_args() !== 1) {
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throw new ArgumentCountError(
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sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())
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);
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}
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if (!\is_resource($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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[$pointer, $prefixLen] = $this->findAddressInTree($ipAddress);
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if ($pointer === 0) {
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return [null, $prefixLen];
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}
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return [$this->resolveDataPointer($pointer), $prefixLen];
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}
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private function findAddressInTree(string $ipAddress): array
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{
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$packedAddr = @inet_pton($ipAddress);
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if ($packedAddr === false) {
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throw new InvalidArgumentException(
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"The value \"$ipAddress\" is not a valid IP address."
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);
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}
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$rawAddress = unpack('C*', $packedAddr);
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$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 = 0;
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$metadata = $this->metadata;
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// Check if we are looking up an IPv4 address in an IPv6 tree. If this
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// is the case, we can skip over the first 96 nodes.
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if ($metadata->ipVersion === 6) {
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if ($bitCount === 32) {
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$node = $this->ipV4Start;
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}
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} elseif ($metadata->ipVersion === 4 && $bitCount === 128) {
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throw new InvalidArgumentException(
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"Error looking up $ipAddress. You attempted to look up an"
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. ' IPv6 address in an IPv4-only database.'
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);
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}
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$nodeCount = $metadata->nodeCount;
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for ($i = 0; $i < $bitCount && $node < $nodeCount; ++$i) {
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$tempBit = 0xFF & $rawAddress[($i >> 3) + 1];
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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 === $nodeCount) {
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// Record is empty
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return [0, $i];
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}
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if ($node > $nodeCount) {
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// Record is a data pointer
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return [$node, $i];
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}
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throw new InvalidDatabaseException(
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'Invalid or corrupt database. Maximum search depth reached without finding a leaf node'
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);
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}
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private function ipV4StartNode(): int
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{
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// If we have an IPv4 database, the start node is the first node
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if ($this->metadata->ipVersion === 4) {
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return 0;
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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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return $node;
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}
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private function readNode(int $nodeNumber, int $index): int
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{
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$baseOffset = $nodeNumber * $this->metadata->nodeByteSize;
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switch ($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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[, $node] = unpack('N', "\x00" . $bytes);
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return $node;
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case 28:
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$bytes = Util::read($this->fileHandle, $baseOffset + 3 * $index, 4);
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if ($index === 0) {
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$middle = (0xF0 & \ord($bytes[3])) >> 4;
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} else {
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$middle = 0x0F & \ord($bytes[0]);
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}
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[, $node] = unpack('N', \chr($middle) . substr($bytes, $index, 3));
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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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[, $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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/**
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* @return mixed
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*/
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private function resolveDataPointer(int $pointer)
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{
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$resolved = $pointer - $this->metadata->nodeCount
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+ $this->metadata->searchTreeSize;
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if ($resolved >= $this->fileSize) {
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throw new InvalidDatabaseException(
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"The MaxMind DB file's search tree is corrupt"
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);
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}
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[$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(string $filename): int
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{
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$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::$METADATA_START_MARKER_LENGTH;
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$minStart = $fileSize - min(self::$METADATA_MAX_SIZE, $fileSize);
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for ($offset = $fileSize - $markerLength; $offset >= $minStart; --$offset) {
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if (fseek($handle, $offset) !== 0) {
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break;
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}
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$value = fread($handle, $markerLength);
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if ($value === $marker) {
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return $offset + $markerLength;
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}
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}
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throw new InvalidDatabaseException(
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"Error opening database file ($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(): Metadata
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{
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if (\func_num_args()) {
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throw new ArgumentCountError(
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sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args())
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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 clone $this->metadata;
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}
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/**
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* Closes the MaxMind DB and returns resources to the system.
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*
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* @throws Exception
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* if an I/O error occurs
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*/
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public function close(): void
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{
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if (\func_num_args()) {
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throw new ArgumentCountError(
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sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args())
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);
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}
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if (!\is_resource($this->fileHandle)) {
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throw new BadMethodCallException(
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'Attempt to 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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