Файл: vendor/maxmind-db/reader/src/MaxMind/Db/Reader/Decoder.php
Строк: 300
<?php
declare(strict_types=1);
namespace MaxMindDbReader;
// @codingStandardsIgnoreLine
use RuntimeException;
class Decoder
{
/**
* @var resource
*/
private $fileStream;
/**
* @var int
*/
private $pointerBase;
/**
* @var float
*/
private $pointerBaseByteSize;
/**
* This is only used for unit testing.
*
* @var bool
*/
private $pointerTestHack;
/**
* @var bool
*/
private $switchByteOrder;
private const _EXTENDED = 0;
private const _POINTER = 1;
private const _UTF8_STRING = 2;
private const _DOUBLE = 3;
private const _BYTES = 4;
private const _UINT16 = 5;
private const _UINT32 = 6;
private const _MAP = 7;
private const _INT32 = 8;
private const _UINT64 = 9;
private const _UINT128 = 10;
private const _ARRAY = 11;
private const _CONTAINER = 12;
private const _END_MARKER = 13;
private const _BOOLEAN = 14;
private const _FLOAT = 15;
/**
* @param resource $fileStream
*/
public function __construct(
$fileStream,
int $pointerBase = 0,
bool $pointerTestHack = false
) {
$this->fileStream = $fileStream;
$this->pointerBase = $pointerBase;
$this->pointerBaseByteSize = $pointerBase > 0 ? log($pointerBase, 2) / 8 : 0;
$this->pointerTestHack = $pointerTestHack;
$this->switchByteOrder = $this->isPlatformLittleEndian();
}
public function decode(int $offset): array
{
$ctrlByte = ord(Util::read($this->fileStream, $offset, 1));
++$offset;
$type = $ctrlByte >> 5;
// Pointers are a special case, we don't read the next $size bytes, we
// use the size to determine the length of the pointer and then follow
// it.
if ($type === self::_POINTER) {
[$pointer, $offset] = $this->decodePointer($ctrlByte, $offset);
// for unit testing
if ($this->pointerTestHack) {
return [$pointer];
}
[$result] = $this->decode($pointer);
return [$result, $offset];
}
if ($type === self::_EXTENDED) {
$nextByte = ord(Util::read($this->fileStream, $offset, 1));
$type = $nextByte + 7;
if ($type < 8) {
throw new InvalidDatabaseException(
'Something went horribly wrong in the decoder. An extended type '
. 'resolved to a type number < 8 ('
. $type
. ')'
);
}
++$offset;
}
[$size, $offset] = $this->sizeFromCtrlByte($ctrlByte, $offset);
return $this->decodeByType($type, $offset, $size);
}
private function decodeByType(int $type, int $offset, int $size): array
{
switch ($type) {
case self::_MAP:
return $this->decodeMap($size, $offset);
case self::_ARRAY:
return $this->decodeArray($size, $offset);
case self::_BOOLEAN:
return [$this->decodeBoolean($size), $offset];
}
$newOffset = $offset + $size;
$bytes = Util::read($this->fileStream, $offset, $size);
switch ($type) {
case self::_BYTES:
case self::_UTF8_STRING:
return [$bytes, $newOffset];
case self::_DOUBLE:
$this->verifySize(8, $size);
return [$this->decodeDouble($bytes), $newOffset];
case self::_FLOAT:
$this->verifySize(4, $size);
return [$this->decodeFloat($bytes), $newOffset];
case self::_INT32:
return [$this->decodeInt32($bytes, $size), $newOffset];
case self::_UINT16:
case self::_UINT32:
case self::_UINT64:
case self::_UINT128:
return [$this->decodeUint($bytes, $size), $newOffset];
default:
throw new InvalidDatabaseException(
'Unknown or unexpected type: ' . $type
);
}
}
private function verifySize(int $expected, int $actual): void
{
if ($expected !== $actual) {
throw new InvalidDatabaseException(
"The MaxMind DB file's data section contains bad data (unknown data type or corrupt data)"
);
}
}
private function decodeArray(int $size, int $offset): array
{
$array = [];
for ($i = 0; $i < $size; ++$i) {
[$value, $offset] = $this->decode($offset);
$array[] = $value;
}
return [$array, $offset];
}
private function decodeBoolean(int $size): bool
{
return $size !== 0;
}
private function decodeDouble(string $bytes): float
{
// This assumes IEEE 754 doubles, but most (all?) modern platforms
// use them.
[, $double] = unpack('E', $bytes);
return $double;
}
private function decodeFloat(string $bytes): float
{
// This assumes IEEE 754 floats, but most (all?) modern platforms
// use them.
[, $float] = unpack('G', $bytes);
return $float;
}
private function decodeInt32(string $bytes, int $size): int
{
switch ($size) {
case 0:
return 0;
case 1:
case 2:
case 3:
$bytes = str_pad($bytes, 4, "x00", STR_PAD_LEFT);
break;
case 4:
break;
default:
throw new InvalidDatabaseException(
"The MaxMind DB file's data section contains bad data (unknown data type or corrupt data)"
);
}
[, $int] = unpack('l', $this->maybeSwitchByteOrder($bytes));
return $int;
}
private function decodeMap(int $size, int $offset): array
{
$map = [];
for ($i = 0; $i < $size; ++$i) {
[$key, $offset] = $this->decode($offset);
[$value, $offset] = $this->decode($offset);
$map[$key] = $value;
}
return [$map, $offset];
}
private function decodePointer(int $ctrlByte, int $offset): array
{
$pointerSize = (($ctrlByte >> 3) & 0x3) + 1;
$buffer = Util::read($this->fileStream, $offset, $pointerSize);
$offset = $offset + $pointerSize;
switch ($pointerSize) {
case 1:
$packed = chr($ctrlByte & 0x7) . $buffer;
[, $pointer] = unpack('n', $packed);
$pointer += $this->pointerBase;
break;
case 2:
$packed = "x00" . chr($ctrlByte & 0x7) . $buffer;
[, $pointer] = unpack('N', $packed);
$pointer += $this->pointerBase + 2048;
break;
case 3:
$packed = chr($ctrlByte & 0x7) . $buffer;
// It is safe to use 'N' here, even on 32 bit machines as the
// first bit is 0.
[, $pointer] = unpack('N', $packed);
$pointer += $this->pointerBase + 526336;
break;
case 4:
// We cannot use unpack here as we might overflow on 32 bit
// machines
$pointerOffset = $this->decodeUint($buffer, $pointerSize);
$pointerBase = $this->pointerBase;
if (PHP_INT_MAX - $pointerBase >= $pointerOffset) {
$pointer = $pointerOffset + $pointerBase;
} else {
throw new RuntimeException(
'The database offset is too large to be represented on your platform.'
);
}
break;
default:
throw new InvalidDatabaseException(
'Unexpected pointer size ' . $pointerSize
);
}
return [$pointer, $offset];
}
// @phpstan-ignore-next-line
private function decodeUint(string $bytes, int $byteLength)
{
if ($byteLength === 0) {
return 0;
}
$integer = 0;
// PHP integers are signed. PHP_INT_SIZE - 1 is the number of
// complete bytes that can be converted to an integer. However,
// we can convert another byte if the leading bit is zero.
$useRealInts = $byteLength <= PHP_INT_SIZE - 1
|| ($byteLength === PHP_INT_SIZE && (ord($bytes[0]) & 0x80) === 0);
for ($i = 0; $i < $byteLength; ++$i) {
$part = ord($bytes[$i]);
// We only use gmp or bcmath if the final value is too big
if ($useRealInts) {
$integer = ($integer << 8) + $part;
} elseif (extension_loaded('gmp')) {
$integer = gmp_strval(gmp_add(gmp_mul((string) $integer, '256'), $part));
} elseif (extension_loaded('bcmath')) {
$integer = bcadd(bcmul((string) $integer, '256'), (string) $part);
} else {
throw new RuntimeException(
'The gmp or bcmath extension must be installed to read this database.'
);
}
}
return $integer;
}
private function sizeFromCtrlByte(int $ctrlByte, int $offset): array
{
$size = $ctrlByte & 0x1F;
if ($size < 29) {
return [$size, $offset];
}
$bytesToRead = $size - 28;
$bytes = Util::read($this->fileStream, $offset, $bytesToRead);
if ($size === 29) {
$size = 29 + ord($bytes);
} elseif ($size === 30) {
[, $adjust] = unpack('n', $bytes);
$size = 285 + $adjust;
} else {
[, $adjust] = unpack('N', "x00" . $bytes);
$size = $adjust + 65821;
}
return [$size, $offset + $bytesToRead];
}
private function maybeSwitchByteOrder(string $bytes): string
{
return $this->switchByteOrder ? strrev($bytes) : $bytes;
}
private function isPlatformLittleEndian(): bool
{
$testint = 0x00FF;
$packed = pack('S', $testint);
return $testint === current(unpack('v', $packed));
}
}