filters.h

研读AxCrypt对加解密的处理方法

#ifndef CRYPTOPP_FILTERS_H
#define CRYPTOPP_FILTERS_H

#include "simple.h"
#include "secblock.h"
#include "misc.h"
#include "smartptr.h"
#include "queue.h"
#include "algparam.h"

NAMESPACE_BEGIN(CryptoPP)

/// provides an implementation of BufferedTransformation's attachment interface
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE Filter : public BufferedTransformation, public NotCopyable
{
public:
	Filter(BufferedTransformation *attachment = NULL);

	bool Attachable() {return true;}
	BufferedTransformation *AttachedTransformation();
	const BufferedTransformation *AttachedTransformation() const;
	void Detach(BufferedTransformation *newAttachment = NULL);

	unsigned int TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel=NULL_CHANNEL, bool blocking=true);
	unsigned int CopyRangeTo2(BufferedTransformation &target, unsigned long &begin, unsigned long end=ULONG_MAX, const std::string &channel=NULL_CHANNEL, bool blocking=true) const;

	void Initialize(const NameValuePairs &parameters=g_nullNameValuePairs, int propagation=-1);
	bool Flush(bool hardFlush, int propagation=-1, bool blocking=true);
	bool MessageSeriesEnd(int propagation=-1, bool blocking=true);

protected:
	virtual BufferedTransformation * NewDefaultAttachment() const;
	void Insert(Filter *nextFilter);	// insert filter after this one

	virtual bool ShouldPropagateMessageEnd() const {return true;}
	virtual bool ShouldPropagateMessageSeriesEnd() const {return true;}

	void PropagateInitialize(const NameValuePairs &parameters, int propagation);

	unsigned int Output(int outputSite, const byte *inString, unsigned int length, int messageEnd, bool blocking, const std::string &channel=NULL_CHANNEL);
	unsigned int OutputModifiable(int outputSite, byte *inString, unsigned int length, int messageEnd, bool blocking, const std::string &channel=NULL_CHANNEL);
	bool OutputMessageEnd(int outputSite, int propagation, bool blocking, const std::string &channel=NULL_CHANNEL);
	bool OutputFlush(int outputSite, bool hardFlush, int propagation, bool blocking, const std::string &channel=NULL_CHANNEL);
	bool OutputMessageSeriesEnd(int outputSite, int propagation, bool blocking, const std::string &channel=NULL_CHANNEL);

private:
	member_ptr<BufferedTransformation> m_attachment;
	
protected:
	unsigned int m_inputPosition;
	int m_continueAt;
};

struct CRYPTOPP_DLL FilterPutSpaceHelper
{
	// desiredSize is how much to ask target, bufferSize is how much to allocate in m_tempSpace
	byte *HelpCreatePutSpace(BufferedTransformation &target, const std::string &channel, unsigned int minSize, unsigned int desiredSize, unsigned int &bufferSize)
	{
		assert(desiredSize >= minSize && bufferSize >= minSize);
		if (m_tempSpace.size() < minSize)
		{
			byte *result = target.ChannelCreatePutSpace(channel, desiredSize);
			if (desiredSize >= minSize)
			{
				bufferSize = desiredSize;
				return result;
			}
			m_tempSpace.New(bufferSize);
		}

		bufferSize = m_tempSpace.size();
		return m_tempSpace.begin();
	}
	byte *HelpCreatePutSpace(BufferedTransformation &target, const std::string &channel, unsigned int minSize)
		{return HelpCreatePutSpace(target, channel, minSize, minSize, minSize);}
	byte *HelpCreatePutSpace(BufferedTransformation &target, const std::string &channel, unsigned int minSize, unsigned int bufferSize)
		{return HelpCreatePutSpace(target, channel, minSize, minSize, bufferSize);}
	SecByteBlock m_tempSpace;
};

//! measure how many byte and messages pass through, also serves as valve
class CRYPTOPP_DLL MeterFilter : public Bufferless<Filter>
{
public:
	MeterFilter(BufferedTransformation *attachment=NULL, bool transparent=true)
		: m_transparent(transparent) {Detach(attachment); ResetMeter();}

	void SetTransparent(bool transparent) {m_transparent = transparent;}
	void ResetMeter() {m_currentMessageBytes = m_totalBytes = m_currentSeriesMessages = m_totalMessages = m_totalMessageSeries = 0;}

	unsigned long GetCurrentMessageBytes() const {return m_currentMessageBytes;}
	unsigned long GetTotalBytes() {return m_totalBytes;}
	unsigned int GetCurrentSeriesMessages() {return m_currentSeriesMessages;}
	unsigned int GetTotalMessages() {return m_totalMessages;}
	unsigned int GetTotalMessageSeries() {return m_totalMessageSeries;}

	byte * CreatePutSpace(unsigned int &size)
		{return AttachedTransformation()->CreatePutSpace(size);}
	unsigned int Put2(const byte *begin, unsigned int length, int messageEnd, bool blocking);
	unsigned int PutModifiable2(byte *inString, unsigned int length, int messageEnd, bool blocking);
	bool IsolatedMessageSeriesEnd(bool blocking);

private:
	bool ShouldPropagateMessageEnd() const {return m_transparent;}
	bool ShouldPropagateMessageSeriesEnd() const {return m_transparent;}

	bool m_transparent;
	unsigned long m_currentMessageBytes, m_totalBytes;
	unsigned int m_currentSeriesMessages, m_totalMessages, m_totalMessageSeries;
};

//! _
class CRYPTOPP_DLL TransparentFilter : public MeterFilter
{
public:
	TransparentFilter(BufferedTransformation *attachment=NULL) : MeterFilter(attachment, true) {}
};

//! _
class CRYPTOPP_DLL OpaqueFilter : public MeterFilter
{
public:
	OpaqueFilter(BufferedTransformation *attachment=NULL) : MeterFilter(attachment, false) {}
};

/*! FilterWithBufferedInput divides up the input stream into
	a first block, a number of middle blocks, and a last block.
	First and last blocks are optional, and middle blocks may
	be a stream instead (i.e. blockSize == 1).
*/
class CRYPTOPP_DLL FilterWithBufferedInput : public Filter
{
public:
	FilterWithBufferedInput(BufferedTransformation *attachment);
	//! firstSize and lastSize may be 0, blockSize must be at least 1
	FilterWithBufferedInput(unsigned int firstSize, unsigned int blockSize, unsigned int lastSize, BufferedTransformation *attachment);

	void IsolatedInitialize(const NameValuePairs &parameters);
	unsigned int Put2(const byte *inString, unsigned int length, int messageEnd, bool blocking)
	{
		return PutMaybeModifiable(const_cast<byte *>(inString), length, messageEnd, blocking, false);
	}
	unsigned int PutModifiable2(byte *inString, unsigned int length, int messageEnd, bool blocking)
	{
		return PutMaybeModifiable(inString, length, messageEnd, blocking, true);
	}
	/*! calls ForceNextPut() if hardFlush is true */
	bool IsolatedFlush(bool hardFlush, bool blocking);

	/*! The input buffer may contain more than blockSize bytes if lastSize != 0.
		ForceNextPut() forces a call to NextPut() if this is the case.
	*/
	void ForceNextPut();

protected:
	bool DidFirstPut() {return m_firstInputDone;}

	virtual void InitializeDerivedAndReturnNewSizes(const NameValuePairs &parameters, unsigned int &firstSize, unsigned int &blockSize, unsigned int &lastSize)
		{InitializeDerived(parameters);}
	virtual void InitializeDerived(const NameValuePairs &parameters) {}
	// FirstPut() is called if (firstSize != 0 and totalLength >= firstSize)
	// or (firstSize == 0 and (totalLength > 0 or a MessageEnd() is received))
	virtual void FirstPut(const byte *inString) =0;
	// NextPut() is called if totalLength >= firstSize+blockSize+lastSize
	virtual void NextPutSingle(const byte *inString) {assert(false);}
	// Same as NextPut() except length can be a multiple of blockSize
	// Either NextPut() or NextPutMultiple() must be overriden
	virtual void NextPutMultiple(const byte *inString, unsigned int length);
	// Same as NextPutMultiple(), but inString can be modified
	virtual void NextPutModifiable(byte *inString, unsigned int length)
		{NextPutMultiple(inString, length);}
	// LastPut() is always called
	// if totalLength < firstSize then length == totalLength
	// else if totalLength <= firstSize+lastSize then length == totalLength-firstSize
	// else lastSize <= length < lastSize+blockSize
	virtual void LastPut(const byte *inString, unsigned int length) =0;
	virtual void FlushDerived() {}

private:
	unsigned int PutMaybeModifiable(byte *begin, unsigned int length, int messageEnd, bool blocking, bool modifiable);
	void NextPutMaybeModifiable(byte *inString, unsigned int length, bool modifiable)
	{
		if (modifiable) NextPutModifiable(inString, length);
		else NextPutMultiple(inString, length);
	}

	// This function should no longer be used, put this here to cause a compiler error
	// if someone tries to override NextPut().
	virtual int NextPut(const byte *inString, unsigned int length) {assert(false); return 0;}

	class BlockQueue
	{
	public:
		void ResetQueue(unsigned int blockSize, unsigned int maxBlocks);
		byte *GetBlock();
		byte *GetContigousBlocks(unsigned int &numberOfBytes);
		unsigned int GetAll(byte *outString);
		void Put(const byte *inString, unsigned int length);
		unsigned int CurrentSize() const {return m_size;}
		unsigned int MaxSize() const {return m_buffer.size();}

	private:
		SecByteBlock m_buffer;
		unsigned int m_blockSize, m_maxBlocks, m_size;
		byte *m_begin;
	};

	unsigned int m_firstSize, m_blockSize, m_lastSize;
	bool m_firstInputDone;
	BlockQueue m_queue;
};

//! _
class CRYPTOPP_DLL FilterWithInputQueue : public Filter
{
public:
	FilterWithInputQueue(BufferedTransformation *attachment) : Filter(attachment) {}
	unsigned int Put2(const byte *inString, unsigned int length, int messageEnd, bool blocking)
	{
		if (!blocking)
			throw BlockingInputOnly("FilterWithInputQueue");
		
		m_inQueue.Put(inString, length);
		if (messageEnd)
		{
			IsolatedMessageEnd(blocking);
			Output(0, NULL, 0, messageEnd, blocking);
		}
		return 0;
	}

protected:
	virtual bool IsolatedMessageEnd(bool blocking) =0;
	void IsolatedInitialize(const NameValuePairs &parameters) {m_inQueue.Clear();}

	ByteQueue m_inQueue;
};

//! Filter Wrapper for StreamTransformation