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/*
* 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 "ClearKeyCryptoPlugin"
#include <utils/Log.h>
#include <endian.h>
#include <media/stagefright/foundation/AString.h>
#include <media/stagefright/foundation/base64.h>
#include <media/stagefright/MediaErrors.h>
#include <string.h>
#include "InitDataParser.h"
#include "ClearKeyUUID.h"
#include "Utils.h"
namespace clearkeydrm {
using android::AString;
using android::String8;
using android::Vector;
namespace {
const size_t kKeyIdSize = 16;
const size_t kSystemIdSize = 16;
}
android::status_t InitDataParser::parse(const Vector<uint8_t>& initData,
const String8& initDataType,
Vector<uint8_t>* licenseRequest) {
// Build a list of the key IDs
Vector<const uint8_t*> keyIds;
if (initDataType == "cenc") {
android::status_t res = parsePssh(initData, &keyIds);
if (res != android::OK) {
return res;
}
} else if (initDataType == "webm") {
// WebM "init data" is just a single key ID
if (initData.size() != kKeyIdSize) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
keyIds.push(initData.array());
} else {
return android::ERROR_DRM_CANNOT_HANDLE;
}
// Build the request
String8 requestJson = generateRequest(keyIds);
licenseRequest->clear();
licenseRequest->appendArray(
reinterpret_cast<const uint8_t*>(requestJson.string()),
requestJson.size());
return android::OK;
}
android::status_t InitDataParser::parsePssh(const Vector<uint8_t>& initData,
Vector<const uint8_t*>* keyIds) {
size_t readPosition = 0;
// Validate size field
uint32_t expectedSize = initData.size();
expectedSize = htonl(expectedSize);
if (memcmp(&initData[readPosition], &expectedSize,
sizeof(expectedSize)) != 0) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
readPosition += sizeof(expectedSize);
// Validate PSSH box identifier
const char psshIdentifier[4] = {'p', 's', 's', 'h'};
if (memcmp(&initData[readPosition], psshIdentifier,
sizeof(psshIdentifier)) != 0) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
readPosition += sizeof(psshIdentifier);
// Validate EME version number
const uint8_t psshVersion1[4] = {1, 0, 0, 0};
if (memcmp(&initData[readPosition], psshVersion1,
sizeof(psshVersion1)) != 0) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
readPosition += sizeof(psshVersion1);
// Validate system ID
if (!isClearKeyUUID(&initData[readPosition])) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
readPosition += kSystemIdSize;
// Read key ID count
uint32_t keyIdCount;
memcpy(&keyIdCount, &initData[readPosition], sizeof(keyIdCount));
keyIdCount = ntohl(keyIdCount);
readPosition += sizeof(keyIdCount);
if (readPosition + (keyIdCount * kKeyIdSize) !=
initData.size() - sizeof(uint32_t)) {
return android::ERROR_DRM_CANNOT_HANDLE;
}
// Calculate the key ID offsets
for (uint32_t i = 0; i < keyIdCount; ++i) {
size_t keyIdPosition = readPosition + (i * kKeyIdSize);
keyIds->push(&initData[keyIdPosition]);
}
return android::OK;
}
String8 InitDataParser::generateRequest(const Vector<const uint8_t*>& keyIds) {
const String8 kRequestPrefix("{\"kids\":[");
const String8 kRequestSuffix("],\"type\":\"temporary\"}");
const String8 kBase64Padding("=");
String8 request(kRequestPrefix);
AString encodedId;
for (size_t i = 0; i < keyIds.size(); ++i) {
encodedId.clear();
android::encodeBase64(keyIds[i], kKeyIdSize, &encodedId);
if (i != 0) {
request.append(",");
}
request.appendFormat("\"%s\"", encodedId.c_str());
}
request.append(kRequestSuffix);
// Android's Base64 encoder produces padding. EME forbids padding.
request.removeAll(kBase64Padding);
return request;
}
} // namespace clearkeydrm
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