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<?php namespace SuperClosure;
use SuperClosure\Analyzer\AstAnalyzer as DefaultAnalyzer;
use SuperClosure\Analyzer\ClosureAnalyzer;
use SuperClosure\Exception\ClosureUnserializationException;
/**
* This is the serializer class used for serializing Closure objects.
*
* We're abstracting away all the details, impossibilities, and scary things
* that happen within.
*/
class Serializer implements SerializerInterface
{
/**
* The special value marking a recursive reference to a closure.
*
* @var string
*/
const RECURSION = "{{RECURSION}}";
/**
* The keys of closure data required for serialization.
*
* @var array
*/
private static $dataToKeep = [
'code' => true,
'context' => true,
'binding' => true,
'scope' => true,
'isStatic' => true,
];
/**
* The closure analyzer instance.
*
* @var ClosureAnalyzer
*/
private $analyzer;
/**
* The HMAC key to sign serialized closures.
*
* @var string
*/
private $signingKey;
/**
* Create a new serializer instance.
*
* @param ClosureAnalyzer|null $analyzer Closure analyzer instance.
* @param string|null $signingKey HMAC key to sign closure data.
*/
public function __construct(
ClosureAnalyzer $analyzer = null,
$signingKey = null
) {
$this->analyzer = $analyzer ?: new DefaultAnalyzer;
$this->signingKey = $signingKey;
}
/**
* @inheritDoc
*/
public function serialize(\Closure $closure)
{
$serialized = serialize(new SerializableClosure($closure, $this));
if ($this->signingKey) {
$signature = $this->calculateSignature($serialized);
$serialized = '%' . base64_encode($signature) . $serialized;
}
return $serialized;
}
/**
* @inheritDoc
*/
public function unserialize($serialized)
{
// Strip off the signature from the front of the string.
$signature = null;
if ($serialized[0] === '%') {
$signature = base64_decode(substr($serialized, 1, 44));
$serialized = substr($serialized, 45);
}
// If a key was provided, then verify the signature.
if ($this->signingKey) {
$this->verifySignature($signature, $serialized);
}
set_error_handler(function () {});
$unserialized = unserialize($serialized);
restore_error_handler();
if ($unserialized === false) {
throw new ClosureUnserializationException(
'The closure could not be unserialized.'
);
} elseif (!$unserialized instanceof SerializableClosure) {
throw new ClosureUnserializationException(
'The closure did not unserialize to a SuperClosure.'
);
}
return $unserialized->getClosure();
}
/**
* @inheritDoc
*/
public function getData(\Closure $closure, $forSerialization = false)
{
// Use the closure analyzer to get data about the closure.
$data = $this->analyzer->analyze($closure);
// If the closure data is getting retrieved solely for the purpose of
// serializing the closure, then make some modifications to the data.
if ($forSerialization) {
// If there is no reference to the binding, don't serialize it.
if (!$data['hasThis']) {
$data['binding'] = null;
}
// Remove data about the closure that does not get serialized.
$data = array_intersect_key($data, self::$dataToKeep);
// Wrap any other closures within the context.
foreach ($data['context'] as &$value) {
if ($value instanceof \Closure) {
$value = ($value === $closure)
? self::RECURSION
: new SerializableClosure($value, $this);
}
}
}
return $data;
}
/**
* Recursively traverses and wraps all Closure objects within the value.
*
* NOTE: THIS MAY NOT WORK IN ALL USE CASES, SO USE AT YOUR OWN RISK.
*
* @param mixed $data Any variable that contains closures.
* @param SerializerInterface $serializer The serializer to use.
*/
public static function wrapClosures(&$data, SerializerInterface $serializer)
{
if ($data instanceof \Closure) {
// Handle and wrap closure objects.
$reflection = new \ReflectionFunction($data);
if ($binding = $reflection->getClosureThis()) {
self::wrapClosures($binding, $serializer);
$scope = $reflection->getClosureScopeClass();
$scope = $scope ? $scope->getName() : 'static';
$data = $data->bindTo($binding, $scope);
}
$data = new SerializableClosure($data, $serializer);
} elseif (is_array($data) || $data instanceof \stdClass || $data instanceof \Traversable) {
// Handle members of traversable values.
foreach ($data as &$value) {
self::wrapClosures($value, $serializer);
}
} elseif (is_object($data) && !$data instanceof \Serializable) {
// Handle objects that are not already explicitly serializable.
$reflection = new \ReflectionObject($data);
if (!$reflection->hasMethod('__sleep')) {
foreach ($reflection->getProperties() as $property) {
if ($property->isPrivate() || $property->isProtected()) {
$property->setAccessible(true);
}
$value = $property->getValue($data);
self::wrapClosures($value, $serializer);
$property->setValue($data, $value);
}
}
}
}
/**
* Calculates a signature for a closure's serialized data.
*
* @param string $data Serialized closure data.
*
* @return string Signature of the closure's data.
*/
private function calculateSignature($data)
{
return hash_hmac('sha256', $data, $this->signingKey, true);
}
/**
* Verifies the signature for a closure's serialized data.
*
* @param string $signature The provided signature of the data.
* @param string $data The data for which to verify the signature.
*
* @throws ClosureUnserializationException if the signature is invalid.
*/
private function verifySignature($signature, $data)
{
// Verify that the provided signature matches the calculated signature.
if (!hash_equals($signature, $this->calculateSignature($data))) {
throw new ClosureUnserializationException('The signature of the'
. ' closure\'s data is invalid, which means the serialized '
. 'closure has been modified and is unsafe to unserialize.'
);
}
}
}
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