// Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

// in_chk.h - IPv6/IPv4 checksum module

// Raw Internet Checksum computation from RMBufChain.

//

/**

 @file in_chk.h

 @publishedAll

 @released

*/

#ifndef __IN_CHK_H__

#define __IN_CHK_H__

#include "in_pkt.h"

/** Checksum calculation.

@publishedAll

@released

*/

class TChecksum {

public:

        // TChecksum can be initialized with an old inverted checksum

        TChecksum(TUint16 aSum = ~0) : iSum((TUint16)~aSum) {}

	inline void Init(TUint16 aSum = ~0);

	inline TUint32 Sum();

        inline TUint32 Sum32();

        inline void Fold();

        inline void Reverse();

        // Complex Add methods

        IMPORT_C void Add(RMBufChain &aPacket, TInt aOffset);

        IMPORT_C void Add(RMBufChain &aPacket, const RMBufPktInfo *aInfo, TInt aOffset);

        // Inline Add methods

        inline void Add(const TUint16 *aPtr, TInt aLength);

        inline void AddHi(TUint8 aByte);

        inline void AddLo(TUint8 aByte);

        inline void Add(TUint16 aHalfWord);

        inline void Add(TUint32 aWord);

        inline void AddH(TUint16 aHalfWord);

        inline void AddH(TUint32 aWord);

        // Static methods

        static inline TUint32 Fold(TUint32 aSum);

        static inline TUint16 ComplementedFold(TUint32 aSum);

        IMPORT_C static TUint32 Calculate(const TUint16 *aPtr, TInt aLength);

private:

	TUint32	iSum;   // 32-bit sum in network byte order

};

/**

// TInet6Checksum Template.

//

//		This template class provides utilitlies to compute and check

//		IPv6 Upper Layer Checksums

//		These are not merged with the TInet6Packet class, because that

//		class is intended (and is used) for all headers, not just upper

//		layers.

//

//	The template parameter (Header class) must

//		- have Checksum() method

//		- have SetChecksum() method

//		- the checkum in header must be aligned to 16 bit word

//

// @publishedAll

// @released

*/

template <class T>

class TInet6Checksum : public TInet6Packet<T>

	{

public:

	TInet6Checksum() {}

	TInet6Checksum(RMBufChain &aPacket) : TInet6Packet<T>(aPacket) {}

	TInet6Checksum(RMBufChain &aPacket, TInt aOffset) : TInet6Packet<T>(aPacket, aOffset) {}

	void ComputeChecksum(RMBufChain &aPacket, const RMBufPktInfo *aInfo, TInt aOffset = 0);

	TBool VerifyChecksum(RMBufChain &aPacket, const RMBufPktInfo *aInfo, TInt aOffset = 0);

	void ComputeChecksum();

	TBool VerifyChecksum();

	};

//

// Inline methods for TChecksum

//

inline void TChecksum::Init(TUint16 aSum)

{

        iSum = ~aSum & 0xffff;

}

inline void TChecksum::Add(const TUint16 *aPtr, TInt aLength)

{

	iSum += Calculate(aPtr, aLength);

}

inline void TChecksum::AddHi(TUint8 aByte)

{

        iSum += (aByte << 8);

}

inline void TChecksum::AddLo(TUint8 aByte)

{

        iSum += aByte;

}

// Add halfword in network byte order

inline void TChecksum::Add(TUint16 aHalfWord)

{

        iSum += aHalfWord;

}

// Add word in network byte order

inline void TChecksum::Add(TUint32 aWord)

{

	iSum += aWord >> 16;

        iSum += aWord & 0xffff;

}

// Add halfword in host byte order

inline void TChecksum::AddH(TUint16 aHalfWord)

{

		__DEBUG_ONLY (const TInt one = 1;)

		ASSERT(*(TUint8*)&one); //check that we are little-endian

		iSum += ((aHalfWord << 8) | (aHalfWord >> 8)) & 0xffff;

}

// Add word in host byte order

inline void TChecksum::AddH(TUint32 aWord)

{

		__DEBUG_ONLY (const TInt one = 1;)

		ASSERT(*(TUint8*)&one); //check that we are little-endian

        iSum += (aWord >> 24);          // add octet  3

        iSum += (aWord >> 8) & 0xffff,  // add octets 2-1

        iSum += (aWord << 8) & 0xff00;  // add octet  0

}

// Fold 32-bit sum into 16 bits

inline void TChecksum::Fold()

{

        iSum = Fold(iSum);

}

// Return 16-bit inverted checksum

inline TUint32 TChecksum::Sum()

{

        return Fold(iSum) ^ 0xffff;

}

// Return 32-bit intermediate sum

inline TUint32 TChecksum::Sum32()

{

        return iSum;

}

// Reverse checksum direction. Can be used to back out partial sums.

inline void TChecksum::Reverse()

{

        iSum = Sum();

}

inline TUint32 TChecksum::Fold(TUint32 aSum)

{

	aSum = (aSum >> 16) + (aSum & 0xffff);  // Max: 0x0001fffe

	aSum += (aSum >> 16);                   // Max: 0x0001ffff

        return aSum & 0xffff;                   // Truncate to 16 bits

}

inline TUint16 TChecksum::ComplementedFold(TUint32 aSum)

{

        return (TUint16)~Fold(aSum);

}

template <class T>

void TInet6Checksum<T>::ComputeChecksum(RMBufChain &aPacket, const RMBufPktInfo *aInfo, TInt aOffset)

	{

        TChecksum sum;

	this->iHdr->SetChecksum(0);

        sum.Add(aPacket, aInfo, aOffset);

	this->iHdr->SetChecksum(sum.Sum());

	}

template <class T>

TBool TInet6Checksum<T>::VerifyChecksum(RMBufChain &aPacket, const RMBufPktInfo *aInfo, TInt aOffset)

	{

        TChecksum sum;

        sum.Add(aPacket, aInfo, aOffset);

        return !sum.Sum();

	}

//

// The following are mainly for the IPv4 Header checksum

//

template <class T>

void TInet6Checksum<T>::ComputeChecksum()

	{

        TChecksum sum;

	this->iHdr->SetChecksum(0);

        sum.Add((TUint16 *)(this->iHdr), this->iHdr->HeaderLength());

	this->iHdr->SetChecksum(sum.Sum());

	}

template <class T>

TBool TInet6Checksum<T>::VerifyChecksum()

	{

        TChecksum sum;

        sum.Add((TUint16*)(this->iHdr), this->iHdr->HeaderLength());

        return !sum.Sum();

	}

#endif