ContentDecrypter.h

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/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file 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.
 */

#ifndef ALEXA_CLIENT_SDK_PLAYLISTPARSER_INCLUDE_PLAYLISTPARSER_CONTENTDECRYPTER_H_
#define ALEXA_CLIENT_SDK_PLAYLISTPARSER_INCLUDE_PLAYLISTPARSER_CONTENTDECRYPTER_H_

#include <atomic>
#include <chrono>
#include <memory>
#include <string>
#include <vector>

#include <AVSCommon/AVS/Attachment/AttachmentWriter.h>
#include <AVSCommon/Utils/RequiresShutdown.h>

#include "PlaylistParser/Id3TagsRemover.h"
#include "PlaylistParser/PlaylistParser.h"

namespace alexaClientSDK {
namespace playlistParser {

typedef std::vector<unsigned char> ByteVector;

class ContentDecrypter : public avsCommon::utils::RequiresShutdown {
public:
    ContentDecrypter();

    void setMediaInitToDecryptedContent(const ByteVector& mediaInitSection, std::chrono::milliseconds totalDuration);

    bool decryptAndWrite(
        const ByteVector& encryptedContent,
        const ByteVector& key,
        const avsCommon::utils::playlistParser::EncryptionInfo& encryptionInfo,
        const std::shared_ptr<avsCommon::avs::attachment::AttachmentWriter>& streamWriter,
        const std::shared_ptr<Id3TagsRemover>& id3TagRemover);

    static bool convertIVToByteArray(const std::string& hexIV, ByteVector* ivByteArray);

    void doShutdown() override;

private:
    ByteVector prependMediaInitSection(const ByteVector& bytes) const;

    int decryptAES(
        const ByteVector& encryptedContent,
        const ByteVector& key,
        const ByteVector& iv,
        ByteVector* decryptedContent,
        bool usePadding = true);

    bool decryptSampleAES(
        const ByteVector& encryptedContent,
        const ByteVector& key,
        const ByteVector& iv,
        const std::shared_ptr<avsCommon::avs::attachment::AttachmentWriter>& streamWriter);

    bool writeToStream(
        const std::shared_ptr<avsCommon::avs::attachment::AttachmentWriter>& streamWriter,
        const unsigned char* buffer,
        size_t size);

    bool writeToStream(
        const ByteVector& content,
        std::shared_ptr<avsCommon::avs::attachment::AttachmentWriter> streamWriter);

    static void logAVError(const char* event, const char* reason, int averror);

    struct ByteBuffer {
        uint8_t* data;

        int len;

        int pos;
    };

    static int bytesRemaining(uint8_t* pos, uint8_t* end);

    ByteVector m_mediaInitSection;

    bool m_needWavHeader;

    std::chrono::milliseconds m_totalDuration;

    std::atomic<bool> m_shuttingDown;
};

}  // namespace playlistParser
}  // namespace alexaClientSDK

#endif  // ALEXA_CLIENT_SDK_PLAYLISTPARSER_INCLUDE_PLAYLISTPARSER_CONTENTDECRYPTER_H_