Proyectos de Subversion Moodle

<?php

declare(strict_types=1);

namespace MaxMind\Db;

use ArgumentCountError;

use BadMethodCallException;

use Exception;

use InvalidArgumentException;

use MaxMind\Db\Reader\Decoder;

use MaxMind\Db\Reader\InvalidDatabaseException;

use MaxMind\Db\Reader\Metadata;

use MaxMind\Db\Reader\Util;

use UnexpectedValueException;

/**

 * Instances of this class provide a reader for the MaxMind DB format. IP

 * addresses can be looked up using the get method.

 */

class Reader

{

    /**

     * @var int

     */

    private static $DATA_SECTION_SEPARATOR_SIZE = 16;

    /**

     * @var string

     */

    private static $METADATA_START_MARKER = "\xAB\xCD\xEFMaxMind.com";

    /**

     * @var int

     */

    private static $METADATA_START_MARKER_LENGTH = 14;

    /**

     * @var int

     */

    private static $METADATA_MAX_SIZE = 131072; // 128 * 1024 = 128KiB

    /**

     * @var Decoder

     */

    private $decoder;

    /**

     * @var resource

     */

    private $fileHandle;

    /**

     * @var int

     */

    private $fileSize;

    /**

     * @var int

     */

    private $ipV4Start;

    /**

     * @var Metadata

     */

    private $metadata;

    /**

     * Constructs a Reader for the MaxMind DB format. The file passed to it must

     * be a valid MaxMind DB file such as a GeoIp2 database file.

     *

     * @param string $database

     *                         the MaxMind DB file to use

     *

     * @throws InvalidArgumentException for invalid database path or unknown arguments

     * @throws InvalidDatabaseException

     *                                  if the database is invalid or there is an error reading

     *                                  from it

     */

    public function __construct(string $database)

    {

        if (\func_num_args() !== 1) {

            throw new ArgumentCountError(

                sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())

            );

        }

        $fileHandle = @fopen($database, 'rb');

        if ($fileHandle === false) {

            throw new InvalidArgumentException(

                "The file \"$database\" does not exist or is not readable."

            );

        }

        $this->fileHandle = $fileHandle;

        $fileSize = @filesize($database);

        if ($fileSize === false) {

            throw new UnexpectedValueException(

                "Error determining the size of \"$database\"."

            );

        }

        $this->fileSize = $fileSize;

        $start = $this->findMetadataStart($database);

        $metadataDecoder = new Decoder($this->fileHandle, $start);

        [$metadataArray] = $metadataDecoder->decode($start);

        $this->metadata = new Metadata($metadataArray);

        $this->decoder = new Decoder(

            $this->fileHandle,

            $this->metadata->searchTreeSize + self::$DATA_SECTION_SEPARATOR_SIZE

        );

        $this->ipV4Start = $this->ipV4StartNode();

    }

    /**

     * Retrieves the record for the IP address.

     *

     * @param string $ipAddress

     *                          the IP address to look up

     *

     * @throws BadMethodCallException   if this method is called on a closed database

     * @throws InvalidArgumentException if something other than a single IP address is passed to the method

     * @throws InvalidDatabaseException

     *                                  if the database is invalid or there is an error reading

     *                                  from it

     *

     * @return mixed the record for the IP address

     */

    public function get(string $ipAddress)

    {

        if (\func_num_args() !== 1) {

            throw new ArgumentCountError(

                sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())

            );

        }

        [$record] = $this->getWithPrefixLen($ipAddress);

        return $record;

    }

    /**

     * Retrieves the record for the IP address and its associated network prefix length.

     *

     * @param string $ipAddress

     *                          the IP address to look up

     *

     * @throws BadMethodCallException   if this method is called on a closed database

     * @throws InvalidArgumentException if something other than a single IP address is passed to the method

     * @throws InvalidDatabaseException

     *                                  if the database is invalid or there is an error reading

     *                                  from it

     *

     * @return array an array where the first element is the record and the

     *               second the network prefix length for the record

     */

    public function getWithPrefixLen(string $ipAddress): array

    {

        if (\func_num_args() !== 1) {

            throw new ArgumentCountError(

                sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args())

            );

        }

        if (!\is_resource($this->fileHandle)) {

            throw new BadMethodCallException(

                'Attempt to read from a closed MaxMind DB.'

            );

        }

        [$pointer, $prefixLen] = $this->findAddressInTree($ipAddress);

        if ($pointer === 0) {

            return [null, $prefixLen];

        }

        return [$this->resolveDataPointer($pointer), $prefixLen];

    }

    private function findAddressInTree(string $ipAddress): array

    {

        $packedAddr = @inet_pton($ipAddress);

        if ($packedAddr === false) {

            throw new InvalidArgumentException(

                "The value \"$ipAddress\" is not a valid IP address."

            );

        }

        $rawAddress = unpack('C*', $packedAddr);

        $bitCount = \count($rawAddress) * 8;

        // The first node of the tree is always node 0, at the beginning of the

        // value

        $node = 0;

        $metadata = $this->metadata;

        // Check if we are looking up an IPv4 address in an IPv6 tree. If this

        // is the case, we can skip over the first 96 nodes.

        if ($metadata->ipVersion === 6) {

            if ($bitCount === 32) {

                $node = $this->ipV4Start;

            }

        } elseif ($metadata->ipVersion === 4 && $bitCount === 128) {

            throw new InvalidArgumentException(

                "Error looking up $ipAddress. You attempted to look up an"

                . ' IPv6 address in an IPv4-only database.'

            );

        }

        $nodeCount = $metadata->nodeCount;

        for ($i = 0; $i < $bitCount && $node < $nodeCount; ++$i) {

            $tempBit = 0xFF & $rawAddress[($i >> 3) + 1];

            $bit = 1 & ($tempBit >> 7 - ($i % 8));

            $node = $this->readNode($node, $bit);

        }

        if ($node === $nodeCount) {

            // Record is empty

            return [0, $i];

        }

        if ($node > $nodeCount) {

            // Record is a data pointer

            return [$node, $i];

        }

        throw new InvalidDatabaseException(

            'Invalid or corrupt database. Maximum search depth reached without finding a leaf node'

        );

    }

    private function ipV4StartNode(): int

    {

        // If we have an IPv4 database, the start node is the first node

        if ($this->metadata->ipVersion === 4) {

            return 0;

        }

        $node = 0;

        for ($i = 0; $i < 96 && $node < $this->metadata->nodeCount; ++$i) {

            $node = $this->readNode($node, 0);

        }

        return $node;

    }

    private function readNode(int $nodeNumber, int $index): int

    {

        $baseOffset = $nodeNumber * $this->metadata->nodeByteSize;

        switch ($this->metadata->recordSize) {

            case 24:

                $bytes = Util::read($this->fileHandle, $baseOffset + $index * 3, 3);

                [, $node] = unpack('N', "\x00" . $bytes);

                return $node;

            case 28:

                $bytes = Util::read($this->fileHandle, $baseOffset + 3 * $index, 4);

                if ($index === 0) {

                    $middle = (0xF0 & \ord($bytes[3])) >> 4;

                } else {

                    $middle = 0x0F & \ord($bytes[0]);

                }

                [, $node] = unpack('N', \chr($middle) . substr($bytes, $index, 3));

                return $node;

            case 32:

                $bytes = Util::read($this->fileHandle, $baseOffset + $index * 4, 4);

                [, $node] = unpack('N', $bytes);

                return $node;

            default:

                throw new InvalidDatabaseException(

                    'Unknown record size: '

                    . $this->metadata->recordSize

                );

        }

    }

    /**

     * @return mixed

     */

    private function resolveDataPointer(int $pointer)

    {

        $resolved = $pointer - $this->metadata->nodeCount

            + $this->metadata->searchTreeSize;

        if ($resolved >= $this->fileSize) {

            throw new InvalidDatabaseException(

                "The MaxMind DB file's search tree is corrupt"

            );

        }

        [$data] = $this->decoder->decode($resolved);

        return $data;

    }

    /*

     * This is an extremely naive but reasonably readable implementation. There

     * are much faster algorithms (e.g., Boyer-Moore) for this if speed is ever

     * an issue, but I suspect it won't be.

     */

    private function findMetadataStart(string $filename): int

    {

        $handle = $this->fileHandle;

        $fstat = fstat($handle);

        $fileSize = $fstat['size'];

        $marker = self::$METADATA_START_MARKER;

        $markerLength = self::$METADATA_START_MARKER_LENGTH;

        $minStart = $fileSize - min(self::$METADATA_MAX_SIZE, $fileSize);

        for ($offset = $fileSize - $markerLength; $offset >= $minStart; --$offset) {

            if (fseek($handle, $offset) !== 0) {

                break;

            }

            $value = fread($handle, $markerLength);

            if ($value === $marker) {

                return $offset + $markerLength;

            }

        }

        throw new InvalidDatabaseException(

            "Error opening database file ($filename). " .

            'Is this a valid MaxMind DB file?'

        );

    }

    /**

     * @throws InvalidArgumentException if arguments are passed to the method

     * @throws BadMethodCallException   if the database has been closed

     *

     * @return Metadata object for the database

     */

    public function metadata(): Metadata

    {

        if (\func_num_args()) {

            throw new ArgumentCountError(

                sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args())

            );

        }

        // Not technically required, but this makes it consistent with

        // C extension and it allows us to change our implementation later.

        if (!\is_resource($this->fileHandle)) {

            throw new BadMethodCallException(

                'Attempt to read from a closed MaxMind DB.'

            );

        }

        return clone $this->metadata;

    }

    /**

     * Closes the MaxMind DB and returns resources to the system.

     *

     * @throws Exception

     *                   if an I/O error occurs

     */

    public function close(): void

    {

        if (\func_num_args()) {

            throw new ArgumentCountError(

                sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args())

            );

        }

        if (!\is_resource($this->fileHandle)) {

            throw new BadMethodCallException(

                'Attempt to close a closed MaxMind DB.'

            );

        }

        fclose($this->fileHandle);

    }

}