// 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:

 // 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