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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
* Copyright (c) 2013-2016 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*/
#ifndef NDN_CXX_SECURITY_TRANSFORM_BASE_HPP
#define NDN_CXX_SECURITY_TRANSFORM_BASE_HPP
#include "../../common.hpp"
#include <vector>
namespace ndn {
namespace security {
namespace transform {
/**
* @file transform-base.hpp
*
* There are three types of module in a transformation chain: Source, Transform, and Sink.
* The ideal usage of the transformation would be:
*
* source(...) >> transform1(...) >> transform2(...) >> sink(...);
*
* When error happens in a module, the module will throw out a transform::Error, one
* can get the location of the module through the getIndex() method of transform::Error.
*/
/**
* @brief Base class of transformation error
*/
class Error : public std::runtime_error
{
public:
Error(size_t index, const std::string& what);
size_t
getIndex() const
{
return m_index;
}
private:
size_t m_index;
};
/**
* @brief The downstream interface of a transformation module
*
* A module can accept input through this interface
*/
class Downstream
{
public:
virtual
~Downstream() = default;
/**
* @brief Accept input data and perform transformation.
*
* An upstream module should call this method to write data into this module.
* The written data will be transformed and the result will be written into the next
* downstream module.
*
* An upstream module can keep calling this method to until end() is called, which
* indicates the end of input. After that, calling this method will cause Error.
*
* If a Downstream implementation expects structured input (e.g., hex decoding requires byte-pair),
* it should not return less than size if final portion of input is not a complete record.
*
* @return number of bytes that has been written into this module
* @throws Error if this module is closed or transformation error happens.
*/
size_t
write(const uint8_t* buf, size_t size);
/**
* @brief Close the input interface of a module.
*
* This method will notify this module that there is no more input and that the module
* should finalize transformation.
*
* Although end() can be invoked multiple times, only the first invocation takes effect.
*/
void
end();
/**
* @brief Check if the input interface of a module is closed.
*/
bool
isEnd() const
{
return m_isEnd;
}
/**
* @brief Set the module index.
*/
void
setIndex(size_t index)
{
m_index = index;
}
/**
* @brief Get the module index.
*/
size_t
getIndex() const
{
return m_index;
}
protected:
Downstream();
private:
/**
* @brief Internal implementation of write method
*/
virtual size_t
doWrite(const uint8_t* buf, size_t size) = 0;
/**
* @brief Internal implementation of end method
*/
virtual void
doEnd() = 0;
private:
bool m_isEnd;
size_t m_index;
};
/**
* @brief The upstream interface of a transformation module
*
* A module can construct subsequent transformation chain through this interface.
*/
class Upstream
{
public:
virtual
~Upstream() = default;
protected:
Upstream();
protected:
/**
* @brief connect to next transformation module
*/
void
appendChain(unique_ptr<Downstream> tail);
Downstream*
getNext()
{
return m_next.get();
}
protected:
unique_ptr<Downstream> m_next;
};
/**
* @brief Abstraction of an intermediate transformation module
*/
class Transform : public Upstream,
public Downstream,
noncopyable
{
protected:
typedef std::vector<uint8_t> OBuffer;
Transform();
/**
* @brief Read the content from output buffer and write it into next module.
*
* It is not guaranteed that all the content in output buffer will be flushed to next module.
*/
void
flushOutputBuffer();
/**
* @brief Read the all the content from output buffer and write it into next module.
* @post isOutputBufferEmpty() returns true.
*/
void
flushAllOutput();
/**
* @brief Set output buffer to @p buffer
*/
void
setOutputBuffer(unique_ptr<OBuffer> buffer);
/**
* @brief Check if output buffer is empty
*/
bool
isOutputBufferEmpty() const;
private:
/**
* @brief Abstraction of data processing in an intermediate module
*/
size_t
doWrite(const uint8_t* data, size_t dataLen) final;
/**
* @brief Finalize transformation in this module
*
* This method will not return until all transformation result is written into next module
*/
void
doEnd() final;
/**
* @brief Process before transformation.
*
* @pre output buffer is empty.
*
* This method is invoked before every convert(...) invocation.
*
* This implementation does nothing. A subclass can override this method to perform
* specific pre-transformation procedure, e.g., read partial transformation results into
* output buffer.
*/
virtual void
preTransform();
/**
* @brief Convert input @p data.
*
* @return The number of input bytes that have been accepted by the converter.
*/
virtual size_t
convert(const uint8_t* data, size_t dataLen) = 0;
/**
* @brief Finalize the transformation.
*
* This implementation only flushes content in output buffer into next module.
* A subclass can override this method to perform specific finalization procedure, i.e.,
* finalize the transformation and flush the result into next module.
*/
virtual void
finalize();
private:
unique_ptr<OBuffer> m_oBuffer;
size_t m_outputOffset;
};
/**
* @brief Abstraction of the transformation sink module
*
* This module does not have next module and can only accept input data
*/
class Sink : public Downstream,
noncopyable
{
};
/**
* @brief Abstraction of the transformation source module
*
* This module can only accept input data from constructor
*/
class Source : public Upstream,
noncopyable
{
public:
/**
* @brief Connect to an intermediate transformation module.
*/
Source&
operator>>(unique_ptr<Transform> transform);
/**
* @brief Connect to the last transformation module.
*
* This method will trigger the source to pump data into the transformation pipeline.
*/
void
operator>>(unique_ptr<Sink> sink);
protected:
Source();
/**
* @brief Pump all data into next transformation module.
*/
void
pump();
/**
* @brief Get the source module index (should always be 0).
*/
size_t
getIndex() const
{
return 0;
}
private:
/**
* @brief Internal implementation of pump().
*/
virtual void
doPump() = 0;
private:
size_t m_nModules; // count of modules in the chain starting from this Source
};
} // namespace transform
} // namespace security
} // namespace ndn
#endif // NDN_CXX_SECURITY_TRANSFORM_BASE_HPP