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

// All rights reserved.

// This component and the accompanying materials are made available

// which accompanies this distribution, and is available

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

// ip6_hdr.h - IPv6 header structure

// This module defines the basic classes for accessing the header

// structures within IPv6 packets.

// Defines the IPv6 header structure.

//

/**

 @file ip6_hdr.h

 @ingroup ip_packet_formats

 @publishedAll

 @released

*/

#ifndef __IP6_HDR_H__

#define __IP6_HDR_H__

#include "in_hdr.h"

#include <in_sock.h> // Only for TIp6Addr !

/**

* @defgroup  ip_packet_formats	IPv4 and IPv6 packet formats and constants

*

* These headers define various constants and special <em>mapping or overlay

* classes</em> to be used in accessing and building the IP packets. The

* mapping classes are not intended to be used in declaring

* variables (although some of them do support that use also).

*

* The normal usage is to typecast a binary buffer

* to a mapping class. For example

* assuming a buf contains a raw IPv6 packet:

*

@code

	TBuf8<2000> buf;

	TInet6HeaderIP &ip = *(TInet6HeaderIP *)buf.Ptr();

	if (ip.MinHeaderLength() > buf.Length() ||

		ip.HeaderLength() + ip.PayloadLength() > buf.Length())

		{

		// Oops. packet too short!

		}

	else if (ip.Version() == 6)

		{

		// Packet seems to be IPv6 packet.

		}

@endcode

*

* Within the TCP/IP stack, the packets are stored in RMBufChain objects.

* The data is not in a contiguous memory area and accessing the headers is

* more complicated. For that purpose there is a template class TInet6Packet,

* which can use any <em>mapping class</em> as a template parameter and

* provides functions to access the header within the chain. Assuming the

* a RMBufChain object buf contains the packet, equivalent code would be:

*

@code

	RMBufChain buf;

	TInet6Packet<TInet6HeaderIP> ip(buf);

	if (ip.iHdr == NULL ||

		ip.iHdr->HeaderLength() + ip.iHdr->PayloadLength() > buf.Length())

		{

		// Opps. packet too short!

		}

	else if (ip.iHdr->Version() == 6)

		{

		// Packet seems to be IPv6 packet.

		}

@endcode

* The TInet6Packet template does automatic MinHeaderLength check. The iHdr

* member variable is set only if the mapping succeeds at least for MinHeaderLength

* octets.

*

* All mapping headers must have the following functions defined:

*

* - static function MinHeaderLength returns the minimum header length in octets.

*

* - static function MaxHeaderLength returns the maximum header length in octets (not used much).

*

* - HeaderLength returns the actual length of a header instance in octets.

*	Note that this may return garbage value, if the mapped header is invalid.

*	The return value can be larger than indicated by MinHeaderLength, and

*	as the mapping is only guaranteed up to that size, user must separately

*	verify the accessibility of a full header in such case. 

* @{

* @}

*/

/**

* @addtogroup  ip_packet_formats

* @{

*/

/**

* The IPv6 minimum value for Maximum Transmission Unit (MTU) as defined in RFC 2460. 

* 

* @since v7.0

*/

const TInt KInet6MinMtu = 1280;

//

// TInet6HeaderIP

// **************

//	Methods of manipulating IPv6 IP header.

//

//	This implementation assumes TUint8 is exactly 8 bits (and not

//	9 or more)

class TInet6HeaderIP

/**

* Encapsulates an IPv6 IP header. 

* @verbatim

 *************************

 Extract from the RFC-2460

 *************************

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |Version| Traffic Class |           Flow Label                  |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |         Payload Length        |  Next Header  |   Hop Limit   |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                                                               |

   +                                                               +

   |                                                               |

   +                         Source Address                        +

   |                                                               |

   +                                                               +

   |                                                               |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                                                               |

   +                                                               +

   |                                                               |

   +                      Destination Address                      +

   |                                                               |

   +                                                               +

   |                                                               |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Version              4-bit Internet Protocol version number = 6.

   Traffic Class        8-bit traffic class field.  See section 7.

   Flow Label           20-bit flow label.  See section 6.

   Payload Length       16-bit unsigned integer.  Length of the IPv6

                        payload, i.e., the rest of the packet following

                        this IPv6 header, in octets.  (Note that any

                        extension headers [section 4] present are

                        considered part of the payload, i.e., included

                        in the length count.)

   Next Header          8-bit selector.  Identifies the type of header

                        immediately following the IPv6 header.  Uses the

                        same values as the IPv4 Protocol field [RFC-1700

                        et seq.].

   Hop Limit            8-bit unsigned integer.  Decremented by 1 by

                        each node that forwards the packet. The packet

                        is discarded if Hop Limit is decremented to

                        zero.

   Source Address       128-bit address of the originator of the packet.

   Destination Address  128-bit address of the intended recipient of the

                        packet (possibly not the ultimate recipient, if

                        a Routing header is present)

@endverbatim

* @publishedAll

* @released

* @since v7.0

*/

	{

public:

	enum TOffsets

		{

		O_PayloadLength = 4,

		O_NextHeader = 6,

		O_HopLimit = 7,

		O_SrcAddr = 8,

		O_DstAddr = 24

		};

	// Basic functions, common to all header classes

	// *********************************************

	/**

	* Gets the header length.	

	* 

	* Note that the header length is fixed.

	* 

	* @return	Header length.

	*/

	inline TInt HeaderLength() const {return 40;}

	/**

	* Gets the minimum header length.

	* 

	* Note that the header length is fixed.

	* 

	* @return	Minimum header length

	*/

	inline static TInt MinHeaderLength() {return 40; }

	/**

	* Gets the maximum header length.

	* 

	* Note that the header length is fixed.

	* 

	* @return	Maximum header length

	*/

	inline static TInt MaxHeaderLength() {return 40; }

	/**

	* Gets a pointer to the byte following the header.

	* 

	* @return	Pointer to the byte following the header

	*/

	inline TUint8 *EndPtr() {return i + HeaderLength();}

	// IPv6 specific methods, get IP header field values from the packet

	// *****************************************************************

	inline TInt Version() const

		/**

		* Gets the IP version from the header.

		*

		* @return	IP version

		*/

		{

		return (i[0] >> 4) & 0xf;

		}

	inline TInt TrafficClass() const

		/**

		* Gets the traffic class from the header.

		*

		* @return	Traffic class

		*/

		{

		return ((i[0] << 4) & 0xf0) | ((i[1] >> 4) & 0x0f);

		}

	inline TInt FlowLabel() const

		/**

		* Gets the flow label from the header.

		* 

		* @return	Flow label (host byte order)

		*/

		{

		return ((i[1] << 16) | (i[2] << 8) | i[3]) & 0xfffff;

		// Could also use any deterministic permutation of the 20 bits,

		// if Flow label can be treated as opaque 20 bits, and not as

		// integer where host/net byte order comes into play --msa

		}

	inline TInt PayloadLength() const

		/**

		* Gets the payload length from the header.

		*

		* @return	Payload length

		*/

		{

		return (i[4] << 8) | i[5];

		}

	inline TInt NextHeader() const

		/**

		* Gets the next header selector from the header.

		*

		* @return	Next header selector (0..255)

		*/

		{

		return i[6];

		}

	inline TInt HopLimit() const

		{

		/**

		* Gets the hop limit from the header.

		*

		* @return	Hop limit (0..255)

		*/

		return i[7];

		}

	//

	// The following return a modifiable reference, so

	// they can be used both for access and build.

	//

	inline TIp6Addr &SrcAddr() const

		/**

		* Gets the source address from the header.

		*

		* @return	Source address

		*/

		{

		return (TIp6Addr &)i[8];

		}

	inline TIp6Addr &DstAddr() const

		/**

		* Gets the destination address from the header.

		*

		* @return	Destination address

		*/

		{

		return (TIp6Addr &)i[24];

		}

	inline TBool EcnIsCongestion()

		/**

		* Gets ECN congestion status.

		*

		* see RFC-3168 for details.

		*

		* @return	True, if CE bit is set on an ECN capable packet.

		*/

		{

		return ((TrafficClass() & 3) == 3);

		}

	// IPv6 specific methods, set IP header field values into the packet

	// *****************************************************************

	inline void Init()

		/**

		* Initialises the header to basic initial values.

		*

		* @li Version = 6

		* @li Traffic Class = 0

		* @li Flow Label = 0

		* @li Payload Length = 0

		* @li Next Header = 0

		* @li Hop Limit = 0

		*

		* The Source and Destination address fields are not touched.

		*/

		{

		static const union { TUint8 a[4]; TUint32 b;} x = { {6 << 4, 0, 0, 0} };

		(TUint32 &)i[0] = x.b;

		(TUint32 &)i[4] = 0;

		}

	inline void SetVersion(TInt aVersion)

		/**

		* Sets the IP version in the header.

		*

		* @param aVersion	IP version (0..15, = 6 for IPv6)

		*/

		{

		i[0] = (TUint8)((i[0] & 0x0f) | ((aVersion << 4) & 0xf0));

		}

	inline void SetTrafficClass(TInt aClass)

		/**

		* Sets the traffic class in the header.

		* 

		* @param aClass	Traffic class (0..255)

		*/

		{

		i[0] = (TUint8)((i[0] & 0xf0) | (aClass >> 4) & 0x0f);

		i[1] = (TUint8)((i[1] & 0x0f) | (aClass << 4) & 0xf0);

		}

	inline void SetFlowLabel(TInt aFlow)

		/**

		* Sets the flow label in the header.

		* 

		* @param aFlow	Flow label (20 bit integer in host order)

		*/

		{

		i[1] = (TUint8)((i[1] & 0xf0) | ((aFlow >> 16) & 0x0f));

		i[2] = (TUint8)(aFlow >> 8);

		i[3] = (TUint8)aFlow;

		}

	inline void SetPayloadLength(TInt aLength)

		/**

		* Sets the payload length in the header.

		* 

		* @param aLength	Payload length

		*/

		{

		i[4] = (TUint8)(aLength >> 8);

		i[5] = (TUint8)aLength;

		}

	inline void SetNextHeader(TInt aNextHeader)

		/**

		* Sets the next header selector from the header.

		*

		* @param aNextHeader	Next header selector (0..255)

		*/

		{

		i[6] = (TUint8)aNextHeader;

		}

	inline void SetHopLimit(TInt aLimit)

		/**

		* Sets the hop limit in the header.

		*

		* @param aLimit	Hop limit (0..255)

		*/

		{

		i[7] = (TUint8)aLimit;

		}

	inline void SetSrcAddr(const TIp6Addr &anAddr)

		/**

		* Sets the source address in the header.

		* 

		* @param anAddr	Source address

		*/

		{

		(TIp6Addr &)i[8] = anAddr;

		}

	inline void SetDstAddr(const TIp6Addr &anAddr)

		/**

		* Sets the destination address in the header.

		* 

		* @param anAddr	Destination address

		*/

		{

		(TIp6Addr &)i[24] = anAddr;

		}

private:

	union

		{

		TUint8 i[40];

		TUint32 iAlign;	// A dummy member to force the 4 byte alignment

		};

	};

/** @} */

#endif