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/*
* Copyright (C) 2017 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 "ecm"
#include <inttypes.h>
#include "ecm.h"
#include "ecm_generator.h"
#include "protos/license_protos.pb.h"
#include <media/stagefright/foundation/ADebug.h>
#include <media/stagefright/MediaErrors.h>
#include <utils/Log.h>
namespace android {
namespace clearkeycas {
Ecm::Ecm()
: asset_id_(0),
asset_id_set_(false),
system_id_(0),
system_id_set_(false) {}
Ecm::~Ecm() {}
status_t Ecm::Parse(const sp<ABuffer>& buffer_as_binary) {
if (buffer_as_binary->size() < kSizeBytes) {
ALOGE("Short Ecm buffer: expected %zu, received %zu.",
kSizeBytes, buffer_as_binary->size());
return BAD_VALUE;
}
Asset asset;
ecm_generator::DefaultEcmFields default_fields;
status_t status = ecm_generator::DecodeECMClearFields(
buffer_as_binary, &asset, &default_fields);
if (status != OK) {
ALOGE("DecodeECMClearFields failed with status %d", status);
return status;
}
set_asset_id(asset.id());
set_system_id(default_fields.system_id);
// Save a copy of the buffer_as_binary for a future DecryptEcm call.
set_buffer(buffer_as_binary);
return OK;
}
status_t Ecm::Decrypt(
const sp<ABuffer>& buffer_as_binary,
const Asset& asset_from_emm) {
// Invariant: asset has id. These are postconditions for Emm::Decrypt().
CHECK(asset_from_emm.has_id());
// DecodeEcm fills in |asset|.id() with the asset_id from the encoded Ecm.
Asset asset(asset_from_emm);
ecm_generator::DefaultEcmFields default_fields;
sp<ABuffer> content_key;
status_t status = ecm_generator::DecodeECM(
buffer_as_binary, &asset, &content_key, &default_fields);
if (status != OK) {
ALOGE("DecodeECM failed with status %d", status);
return status;
}
if (asset.id() != asset_from_emm.id()) {
ALOGE("Asset_id from Emm (%" PRIu64 ") does not match asset_id from Ecm (%" PRIu64 ").",
asset_from_emm.id(), asset.id());
return CLEARKEY_STATUS_INVALID_PARAMETER;
}
set_asset_id(asset.id());
set_system_id(default_fields.system_id);
set_content_key(content_key);
return status;
}
EcmDescriptor::EcmDescriptor() : ecm_set_(false), id_(0), id_set_(false) {}
EcmDescriptor::EcmDescriptor(uint16_t id, const Ecm& ecm)
: ecm_(ecm), ecm_set_(true), id_(id), id_set_(true) {}
EcmDescriptor::~EcmDescriptor() {}
status_t EcmDescriptor::Parse(const sp<ABuffer>& buffer_as_binary) {
if (buffer_as_binary->size() < kSizeBytes) {
ALOGE("Short EcmDescriptor buffer: expected %zu, received %zu.",
kSizeBytes, buffer_as_binary->size());
return BAD_VALUE;
}
sp<ABuffer> id_buffer = new ABuffer(buffer_as_binary->data(), kIdSizeBytes);
const uint8_t *id_bytes = id_buffer->data();
uint16_t id = (id_bytes[0] << 8) | id_bytes[1];
set_id(id);
// Unmarshall the contained Ecm.
sp<ABuffer> ecm_buffer = new ABuffer(
buffer_as_binary->data() + kIdSizeBytes, Ecm::kSizeBytes);
status_t status = mutable_ecm()->Parse(ecm_buffer);
if (status != OK) {
return status;
}
return OK;
}
EcmContainer::EcmContainer() : count_(0), count_set_(false) {}
EcmContainer::~EcmContainer() {}
status_t EcmContainer::Add(const EcmDescriptor& descriptor) {
switch (count_) {
case 0:
descriptor_[0] = descriptor;
count_ = 1;
break;
case 1:
descriptor_[1] = descriptor;
count_ = 2;
break;
case 2:
descriptor_[0] = descriptor_[1];
descriptor_[1] = descriptor;
break;
default:
ALOGE("Bad state.");
return INVALID_OPERATION;
}
count_set_ = true;
return OK;
}
status_t EcmContainer::Parse(const sp<ABuffer>& buffer_as_binary) {
// EcmContainer can contain 1 or 2 EcmDescriptors so this is a check for
// minimum size.
if (buffer_as_binary->size() < kMinimumSizeBytes) {
ALOGE("Short EcmContainer buffer: expected >= %zu, received %zu.",
kMinimumSizeBytes, buffer_as_binary->size());
return BAD_VALUE;
}
sp<ABuffer> count_buffer = new ABuffer(
buffer_as_binary->data(), kCountSizeBytes);
const uint8_t *count_bytes = count_buffer->data();
size_t count = (count_bytes[0] << 8) | count_bytes[1];
// Check that count is a legal value.
if (!CountLegal(count)) {
ALOGE("Invalid descriptor count: expected %zu <= count <= %zu, received %zu.",
kMinDescriptorCount, kMaxDescriptorCount, count);
return ERROR_OUT_OF_RANGE;
}
// If needed, check that buffer_as_binary can hold 2 EcmDescriptors.
if (count > kMinDescriptorCount) {
size_t expected_bytes =
kCountSizeBytes + (count * EcmDescriptor::kSizeBytes);
if (buffer_as_binary->size() < expected_bytes) {
ALOGE("Short EcmContainer buffer: expected %zu, received %zu.",
expected_bytes, buffer_as_binary->size());
return BAD_VALUE;
}
}
set_count(count);
// Unmarshall the contained EcmDescriptors.
size_t offset = kCountSizeBytes;
for (size_t i = 0; i < count_; ++i) {
sp<ABuffer> descriptor_buffer = new ABuffer(
buffer_as_binary->data() + offset, EcmDescriptor::kSizeBytes);
status_t status = mutable_descriptor(i)->Parse(descriptor_buffer);
if (status != OK) {
return status;
}
offset += EcmDescriptor::kSizeBytes;
}
return OK;
}
} // namespace clearkeycas
} // namespace android
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