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