/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//#define LOG_NDEBUG 0
#define LOG_TAG "NdkMediaDrm"
#include "NdkMediaDrm.h"
#include <cutils/properties.h>
#include <utils/Log.h>
#include <utils/StrongPointer.h>
#include <gui/Surface.h>
#include <media/IDrm.h>
#include <media/IDrmClient.h>
#include <media/stagefright/MediaErrors.h>
#include <binder/IServiceManager.h>
#include <media/IMediaDrmService.h>
#include <ndk/NdkMediaCrypto.h>
using namespace android;
typedef Vector<uint8_t> idvec_t;
struct DrmListener: virtual public BnDrmClient
{
private:
AMediaDrm *mObj;
AMediaDrmEventListener mListener;
public:
DrmListener(AMediaDrm *obj, AMediaDrmEventListener listener) : mObj(obj), mListener(listener) {}
void notify(DrmPlugin::EventType eventType, int extra, const Parcel *obj);
};
struct AMediaDrm {
sp<IDrm> mDrm;
sp<IDrmClient> mDrmClient;
List<idvec_t> mIds;
KeyedVector<String8, String8> mQueryResults;
Vector<uint8_t> mKeyRequest;
Vector<uint8_t> mProvisionRequest;
String8 mProvisionUrl;
String8 mPropertyString;
Vector<uint8_t> mPropertyByteArray;
List<Vector<uint8_t> > mSecureStops;
sp<DrmListener> mListener;
};
void DrmListener::notify(DrmPlugin::EventType eventType, int extra, const Parcel *obj) {
if (!mListener) {
return;
}
AMediaDrmSessionId sessionId = {NULL, 0};
int32_t sessionIdSize = obj->readInt32();
if (sessionIdSize) {
uint8_t *sessionIdData = new uint8_t[sessionIdSize];
sessionId.ptr = sessionIdData;
sessionId.length = sessionIdSize;
obj->read(sessionIdData, sessionId.length);
}
int32_t dataSize = obj->readInt32();
uint8_t *data = NULL;
if (dataSize) {
data = new uint8_t[dataSize];
obj->read(data, dataSize);
}
// translate DrmPlugin event types into their NDK equivalents
AMediaDrmEventType ndkEventType;
switch(eventType) {
case DrmPlugin::kDrmPluginEventProvisionRequired:
ndkEventType = EVENT_PROVISION_REQUIRED;
break;
case DrmPlugin::kDrmPluginEventKeyNeeded:
ndkEventType = EVENT_KEY_REQUIRED;
break;
case DrmPlugin::kDrmPluginEventKeyExpired:
ndkEventType = EVENT_KEY_EXPIRED;
break;
case DrmPlugin::kDrmPluginEventVendorDefined:
ndkEventType = EVENT_VENDOR_DEFINED;
break;
default:
ALOGE("Invalid event DrmPlugin::EventType %d, ignored", (int)eventType);
goto cleanup;
}
(*mListener)(mObj, &sessionId, ndkEventType, extra, data, dataSize);
cleanup:
delete [] sessionId.ptr;
delete [] data;
}
extern "C" {
static media_status_t translateStatus(status_t status) {
media_status_t result = AMEDIA_ERROR_UNKNOWN;
switch (status) {
case OK:
result = AMEDIA_OK;
break;
case android::ERROR_DRM_NOT_PROVISIONED:
result = AMEDIA_DRM_NOT_PROVISIONED;
break;
case android::ERROR_DRM_RESOURCE_BUSY:
result = AMEDIA_DRM_RESOURCE_BUSY;
break;
case android::ERROR_DRM_DEVICE_REVOKED:
result = AMEDIA_DRM_DEVICE_REVOKED;
break;
case android::ERROR_DRM_CANNOT_HANDLE:
result = AMEDIA_ERROR_INVALID_PARAMETER;
break;
case android::ERROR_DRM_TAMPER_DETECTED:
result = AMEDIA_DRM_TAMPER_DETECTED;
break;
case android::ERROR_DRM_SESSION_NOT_OPENED:
result = AMEDIA_DRM_SESSION_NOT_OPENED;
break;
case android::ERROR_DRM_NO_LICENSE:
result = AMEDIA_DRM_NEED_KEY;
break;
case android::ERROR_DRM_LICENSE_EXPIRED:
result = AMEDIA_DRM_LICENSE_EXPIRED;
break;
default:
break;
}
return result;
}
static sp<IDrm> CreateDrm() {
sp<IServiceManager> sm = defaultServiceManager();
sp<IBinder> binder = sm->getService(String16("media.drm"));
sp<IMediaDrmService> service = interface_cast<IMediaDrmService>(binder);
if (service == NULL) {
return NULL;
}
sp<IDrm> drm = service->makeDrm();
if (drm == NULL || (drm->initCheck() != OK && drm->initCheck() != NO_INIT)) {
return NULL;
}
return drm;
}
static sp<IDrm> CreateDrmFromUUID(const AMediaUUID uuid) {
sp<IDrm> drm = CreateDrm();
if (drm == NULL) {
return NULL;
}
String8 nullPackageName;
status_t err = drm->createPlugin(uuid, nullPackageName);
if (err != OK) {
return NULL;
}
return drm;
}
EXPORT
bool AMediaDrm_isCryptoSchemeSupported(const AMediaUUID uuid, const char *mimeType) {
sp<IDrm> drm = CreateDrm();
if (drm == NULL) {
return false;
}
String8 mimeStr = mimeType ? String8(mimeType) : String8("");
return drm->isCryptoSchemeSupported(uuid, mimeStr);
}
EXPORT
AMediaDrm* AMediaDrm_createByUUID(const AMediaUUID uuid) {
AMediaDrm *mObj = new AMediaDrm();
mObj->mDrm = CreateDrmFromUUID(uuid);
return mObj;
}
EXPORT
void AMediaDrm_release(AMediaDrm *mObj) {
if (mObj->mDrm != NULL) {
mObj->mDrm->setListener(NULL);
mObj->mDrm->destroyPlugin();
mObj->mDrm.clear();
}
delete mObj;
}
EXPORT
media_status_t AMediaDrm_setOnEventListener(AMediaDrm *mObj, AMediaDrmEventListener listener) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
mObj->mListener = new DrmListener(mObj, listener);
mObj->mDrm->setListener(mObj->mListener);
return AMEDIA_OK;
}
static bool findId(AMediaDrm *mObj, const AMediaDrmByteArray &id, List<idvec_t>::iterator &iter) {
for (iter = mObj->mIds.begin(); iter != mObj->mIds.end(); ++iter) {
if (iter->array() == id.ptr && iter->size() == id.length) {
return true;
}
}
return false;
}
EXPORT
media_status_t AMediaDrm_openSession(AMediaDrm *mObj, AMediaDrmSessionId *sessionId) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
Vector<uint8_t> session;
status_t status = mObj->mDrm->openSession(session);
if (status == OK) {
mObj->mIds.push_front(session);
List<idvec_t>::iterator iter = mObj->mIds.begin();
sessionId->ptr = iter->array();
sessionId->length = iter->size();
}
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_closeSession(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
mObj->mDrm->closeSession(*iter);
mObj->mIds.erase(iter);
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_getKeyRequest(AMediaDrm *mObj, const AMediaDrmScope *scope,
const uint8_t *init, size_t initSize, const char *mimeType, AMediaDrmKeyType keyType,
const AMediaDrmKeyValue *optionalParameters, size_t numOptionalParameters,
const uint8_t **keyRequest, size_t *keyRequestSize) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!mimeType || !scope || !keyRequest || !keyRequestSize) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *scope, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
Vector<uint8_t> mdInit;
mdInit.appendArray(init, initSize);
DrmPlugin::KeyType mdKeyType;
switch (keyType) {
case KEY_TYPE_STREAMING:
mdKeyType = DrmPlugin::kKeyType_Streaming;
break;
case KEY_TYPE_OFFLINE:
mdKeyType = DrmPlugin::kKeyType_Offline;
break;
case KEY_TYPE_RELEASE:
mdKeyType = DrmPlugin::kKeyType_Release;
break;
default:
return AMEDIA_ERROR_INVALID_PARAMETER;
}
KeyedVector<String8, String8> mdOptionalParameters;
for (size_t i = 0; i < numOptionalParameters; i++) {
mdOptionalParameters.add(String8(optionalParameters[i].mKey),
String8(optionalParameters[i].mValue));
}
String8 defaultUrl;
DrmPlugin::KeyRequestType keyRequestType;
status_t status = mObj->mDrm->getKeyRequest(*iter, mdInit, String8(mimeType),
mdKeyType, mdOptionalParameters, mObj->mKeyRequest, defaultUrl,
&keyRequestType);
if (status != OK) {
return translateStatus(status);
} else {
*keyRequest = mObj->mKeyRequest.array();
*keyRequestSize = mObj->mKeyRequest.size();
}
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_provideKeyResponse(AMediaDrm *mObj, const AMediaDrmScope *scope,
const uint8_t *response, size_t responseSize, AMediaDrmKeySetId *keySetId) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!scope || !response || !responseSize || !keySetId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *scope, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
Vector<uint8_t> mdResponse;
mdResponse.appendArray(response, responseSize);
Vector<uint8_t> mdKeySetId;
status_t status = mObj->mDrm->provideKeyResponse(*iter, mdResponse, mdKeySetId);
if (status == OK) {
mObj->mIds.push_front(mdKeySetId);
List<idvec_t>::iterator iter = mObj->mIds.begin();
keySetId->ptr = iter->array();
keySetId->length = iter->size();
} else {
keySetId->ptr = NULL;
keySetId->length = 0;
}
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_restoreKeys(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
const AMediaDrmKeySetId *keySetId) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId || !keySetId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
Vector<uint8_t> keySet;
keySet.appendArray(keySetId->ptr, keySetId->length);
return translateStatus(mObj->mDrm->restoreKeys(*iter, keySet));
}
EXPORT
media_status_t AMediaDrm_removeKeys(AMediaDrm *mObj, const AMediaDrmSessionId *keySetId) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!keySetId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
status_t status;
if (!findId(mObj, *keySetId, iter)) {
Vector<uint8_t> keySet;
keySet.appendArray(keySetId->ptr, keySetId->length);
status = mObj->mDrm->removeKeys(keySet);
} else {
status = mObj->mDrm->removeKeys(*iter);
mObj->mIds.erase(iter);
}
return translateStatus(status);
}
EXPORT
media_status_t AMediaDrm_queryKeyStatus(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
AMediaDrmKeyValue *keyValuePairs, size_t *numPairs) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId || !numPairs) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
status_t status = mObj->mDrm->queryKeyStatus(*iter, mObj->mQueryResults);
if (status != OK) {
*numPairs = 0;
return translateStatus(status);
}
if (mObj->mQueryResults.size() > *numPairs) {
*numPairs = mObj->mQueryResults.size();
return AMEDIA_DRM_SHORT_BUFFER;
}
for (size_t i = 0; i < mObj->mQueryResults.size(); i++) {
keyValuePairs[i].mKey = mObj->mQueryResults.keyAt(i).string();
keyValuePairs[i].mValue = mObj->mQueryResults.keyAt(i).string();
}
*numPairs = mObj->mQueryResults.size();
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_getProvisionRequest(AMediaDrm *mObj, const uint8_t **provisionRequest,
size_t *provisionRequestSize, const char **serverUrl) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!provisionRequest || !provisionRequestSize || !*provisionRequestSize || !serverUrl) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
status_t status = mObj->mDrm->getProvisionRequest(String8(""), String8(""),
mObj->mProvisionRequest, mObj->mProvisionUrl);
if (status != OK) {
return translateStatus(status);
} else {
*provisionRequest = mObj->mProvisionRequest.array();
*provisionRequestSize = mObj->mProvisionRequest.size();
*serverUrl = mObj->mProvisionUrl.string();
}
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_provideProvisionResponse(AMediaDrm *mObj,
const uint8_t *response, size_t responseSize) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!response || !responseSize) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
Vector<uint8_t> mdResponse;
mdResponse.appendArray(response, responseSize);
Vector<uint8_t> unused;
return translateStatus(mObj->mDrm->provideProvisionResponse(mdResponse, unused, unused));
}
EXPORT
media_status_t AMediaDrm_getSecureStops(AMediaDrm *mObj,
AMediaDrmSecureStop *secureStops, size_t *numSecureStops) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!numSecureStops) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
status_t status = mObj->mDrm->getSecureStops(mObj->mSecureStops);
if (status != OK) {
*numSecureStops = 0;
return translateStatus(status);
}
if (*numSecureStops < mObj->mSecureStops.size()) {
return AMEDIA_DRM_SHORT_BUFFER;
}
List<Vector<uint8_t> >::iterator iter = mObj->mSecureStops.begin();
size_t i = 0;
while (iter != mObj->mSecureStops.end()) {
secureStops[i].ptr = iter->array();
secureStops[i].length = iter->size();
++iter;
++i;
}
*numSecureStops = mObj->mSecureStops.size();
return AMEDIA_OK;
}
EXPORT
media_status_t AMediaDrm_releaseSecureStops(AMediaDrm *mObj,
const AMediaDrmSecureStop *ssRelease) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!ssRelease) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
Vector<uint8_t> release;
release.appendArray(ssRelease->ptr, ssRelease->length);
return translateStatus(mObj->mDrm->releaseSecureStops(release));
}
EXPORT
media_status_t AMediaDrm_getPropertyString(AMediaDrm *mObj, const char *propertyName,
const char **propertyValue) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!propertyName || !propertyValue) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
status_t status = mObj->mDrm->getPropertyString(String8(propertyName),
mObj->mPropertyString);
if (status == OK) {
*propertyValue = mObj->mPropertyString.string();
} else {
*propertyValue = NULL;
}
return translateStatus(status);
}
EXPORT
media_status_t AMediaDrm_getPropertyByteArray(AMediaDrm *mObj,
const char *propertyName, AMediaDrmByteArray *propertyValue) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!propertyName || !propertyValue) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
status_t status = mObj->mDrm->getPropertyByteArray(String8(propertyName),
mObj->mPropertyByteArray);
if (status == OK) {
propertyValue->ptr = mObj->mPropertyByteArray.array();
propertyValue->length = mObj->mPropertyByteArray.size();
} else {
propertyValue->ptr = NULL;
propertyValue->length = 0;
}
return translateStatus(status);
}
EXPORT
media_status_t AMediaDrm_setPropertyString(AMediaDrm *mObj,
const char *propertyName, const char *value) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
return translateStatus(mObj->mDrm->setPropertyString(String8(propertyName),
String8(value)));
}
EXPORT
media_status_t AMediaDrm_setPropertyByteArray(AMediaDrm *mObj,
const char *propertyName, const uint8_t *value, size_t valueSize) {
Vector<uint8_t> byteArray;
byteArray.appendArray(value, valueSize);
return translateStatus(mObj->mDrm->getPropertyByteArray(String8(propertyName),
byteArray));
}
static media_status_t encrypt_decrypt_common(AMediaDrm *mObj,
const AMediaDrmSessionId &sessionId,
const char *cipherAlgorithm, uint8_t *keyId, uint8_t *iv,
const uint8_t *input, uint8_t *output, size_t dataSize, bool encrypt) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
status_t status = mObj->mDrm->setCipherAlgorithm(*iter, String8(cipherAlgorithm));
if (status != OK) {
return translateStatus(status);
}
Vector<uint8_t> keyIdVec;
const size_t kKeyIdSize = 16;
keyIdVec.appendArray(keyId, kKeyIdSize);
Vector<uint8_t> inputVec;
inputVec.appendArray(input, dataSize);
Vector<uint8_t> ivVec;
const size_t kIvSize = 16;
ivVec.appendArray(iv, kIvSize);
Vector<uint8_t> outputVec;
if (encrypt) {
status = mObj->mDrm->encrypt(*iter, keyIdVec, inputVec, ivVec, outputVec);
} else {
status = mObj->mDrm->decrypt(*iter, keyIdVec, inputVec, ivVec, outputVec);
}
if (status == OK) {
memcpy(output, outputVec.array(), outputVec.size());
}
return translateStatus(status);
}
EXPORT
media_status_t AMediaDrm_encrypt(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
const char *cipherAlgorithm, uint8_t *keyId, uint8_t *iv,
const uint8_t *input, uint8_t *output, size_t dataSize) {
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
return encrypt_decrypt_common(mObj, *sessionId, cipherAlgorithm, keyId, iv,
input, output, dataSize, true);
}
EXPORT
media_status_t AMediaDrm_decrypt(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
const char *cipherAlgorithm, uint8_t *keyId, uint8_t *iv,
const uint8_t *input, uint8_t *output, size_t dataSize) {
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
return encrypt_decrypt_common(mObj, *sessionId, cipherAlgorithm, keyId, iv,
input, output, dataSize, false);
}
EXPORT
media_status_t AMediaDrm_sign(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
const char *macAlgorithm, uint8_t *keyId, uint8_t *message, size_t messageSize,
uint8_t *signature, size_t *signatureSize) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
status_t status = mObj->mDrm->setMacAlgorithm(*iter, String8(macAlgorithm));
if (status != OK) {
return translateStatus(status);
}
Vector<uint8_t> keyIdVec;
const size_t kKeyIdSize = 16;
keyIdVec.appendArray(keyId, kKeyIdSize);
Vector<uint8_t> messageVec;
messageVec.appendArray(message, messageSize);
Vector<uint8_t> signatureVec;
status = mObj->mDrm->sign(*iter, keyIdVec, messageVec, signatureVec);
if (signatureVec.size() > *signatureSize) {
return AMEDIA_DRM_SHORT_BUFFER;
}
if (status == OK) {
memcpy(signature, signatureVec.array(), signatureVec.size());
}
return translateStatus(status);
}
EXPORT
media_status_t AMediaDrm_verify(AMediaDrm *mObj, const AMediaDrmSessionId *sessionId,
const char *macAlgorithm, uint8_t *keyId, const uint8_t *message, size_t messageSize,
const uint8_t *signature, size_t signatureSize) {
if (!mObj || mObj->mDrm == NULL) {
return AMEDIA_ERROR_INVALID_OBJECT;
}
if (!sessionId) {
return AMEDIA_ERROR_INVALID_PARAMETER;
}
List<idvec_t>::iterator iter;
if (!findId(mObj, *sessionId, iter)) {
return AMEDIA_DRM_SESSION_NOT_OPENED;
}
status_t status = mObj->mDrm->setMacAlgorithm(*iter, String8(macAlgorithm));
if (status != OK) {
return translateStatus(status);
}
Vector<uint8_t> keyIdVec;
const size_t kKeyIdSize = 16;
keyIdVec.appendArray(keyId, kKeyIdSize);
Vector<uint8_t> messageVec;
messageVec.appendArray(message, messageSize);
Vector<uint8_t> signatureVec;
signatureVec.appendArray(signature, signatureSize);
bool match;
status = mObj->mDrm->verify(*iter, keyIdVec, messageVec, signatureVec, match);
if (status == OK) {
return match ? AMEDIA_OK : AMEDIA_DRM_VERIFY_FAILED;
}
return translateStatus(status);
}
} // extern "C"