107 lines
3.1 KiB
C++
107 lines
3.1 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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//#define LOG_NDEBUG 0
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#define LOG_TAG "ecm_generator"
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#include "ecm_generator.h"
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#include <string.h>
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#include <algorithm>
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#include <endian.h>
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#include "protos/license_protos.pb.h"
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#include <media/stagefright/foundation/ADebug.h>
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#include <media/stagefright/MediaErrors.h>
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#include <openssl/aes.h>
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#include <utils/Log.h>
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namespace android {
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namespace clearkeycas {
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// These constants are internal to this module.
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const uint16_t kEcmClearFieldsSize = 16;
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const uint32_t kContentKeyByteSize = 16;
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const uint16_t kTotalEcmSize =
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kEcmClearFieldsSize + kContentKeyByteSize; // clear fields + clear key
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#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32_t *>(_p))
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static uint32_t Load32(const void *p) {
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return ntohl(UNALIGNED_LOAD32(p));
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}
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static uint32_t LoadNext32(const uint8_t** pptr) {
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CHECK(pptr);
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CHECK(*pptr);
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const uint8_t* p = *pptr;
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*pptr += sizeof(uint32_t);
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return Load32(p);
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}
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namespace ecm_generator {
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status_t DecodeECM(const sp<ABuffer>& ecm, Asset* asset,
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sp<ABuffer> *content_key, DefaultEcmFields* default_fields) {
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CHECK(asset);
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CHECK(content_key);
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CHECK(default_fields);
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status_t status = DecodeECMClearFields(ecm, asset, default_fields);
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if (status != OK) {
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return status;
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}
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const uint8_t* ptr = ecm->data() + kEcmClearFieldsSize;
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*content_key = new ABuffer(kContentKeyByteSize);
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memcpy((*content_key)->data(), ptr, kContentKeyByteSize);
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return OK;
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}
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status_t DecodeECMClearFields(const sp<ABuffer>& ecm, Asset* asset,
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DefaultEcmFields* default_fields) {
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CHECK(asset);
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CHECK(default_fields);
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if (ecm->size() < kTotalEcmSize) {
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ALOGE("Short ECM: expected_length=%d, actual_length=%zu",
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kTotalEcmSize, ecm->size());
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return BAD_VALUE;
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}
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const uint8_t* ptr = ecm->data();
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default_fields->old_version = LoadNext32(&ptr);
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default_fields->clear_lead = LoadNext32(&ptr);
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default_fields->system_id = LoadNext32(&ptr);
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// The real ecm version is hidden in the system id.
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default_fields->ecm_version = (default_fields->system_id >> 24) & 0xFF;
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default_fields->system_id &= 0x00FFFFFF;
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if (default_fields->system_id == 0) {
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ALOGE("Ecm has invalid system_id 0");
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return CLEARKEY_STATUS_INVALIDSYSTEMID;
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}
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asset->set_id(LoadNext32(&ptr));
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if (asset->id() == 0) {
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ALOGE("Ecm has invalid asset_id 0");
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return CLEARKEY_STATUS_INVALIDASSETID;
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}
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return OK;
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}
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} // namespace ecm_generator
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} // namespace clearkeycas
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} // namespace android
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