// 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:

// ip4_hdr.h - IPv4 header structure

// Defines the basic classes for accessing the header

// structures within IPv4 packets.

//

/**

 @file ip4_hdr.h

 @ingroup ip_packet_formats

 @publishedAll

 @released

*/

#ifndef __IP4_HDR_H__

#define __IP4_HDR_H__

#include "in_hdr.h"

#include "es_sock.h"		// for ByteOrder only!!!

/**

* @addtogroup ip_packet_formats

* @{

*/

/**

* @name IP v4 constants 

* @since v7.0

* @publishedAll

* @released

*/

class TInet6HeaderIP4

/**

*	Encapsulates an IPv4 IP header. 

* 

@verbatim

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

  Extract from the RFC-791

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

  0                   1                   2                   3

  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

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

  |Version|  IHL  |Type of Service|          Total Length         |

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

  |         Identification        |Flags|      Fragment Offset    |

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

  |  Time to Live |    Protocol   |         Header Checksum       |

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

  |                       Source Address                          |

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

  |                    Destination Address                        |

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

  |                    Options                    |    Padding    |

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

  Version:  4 bits = 4

  IHL:  4 bits

    Internet Header Length is the length of the internet header in 32

    bit words, and thus points to the beginning of the data.  Note that

    the minimum value for a correct header is 5

  Type of Service:  8 bits

      Bits 0-2:  Precedence.

      Bit    3:  0 = Normal Delay,      1 = Low Delay.

      Bits   4:  0 = Normal Throughput, 1 = High Throughput.

      Bits   5:  0 = Normal Relibility, 1 = High Relibility.

      Bit  6-7:  Reserved for Future Use.

	  Precedence

          111 - Network Control

          110 - Internetwork Control

          101 - CRITIC/ECP

          100 - Flash Override

          011 - Flash

          010 - Immediate

          001 - Priority

          000 - Routine

  Total Length:  16 bits

    Total Length is the length of the datagram, measured in octets,

    including internet header and data.

  Identification:  16 bits

    An identifying value assigned by the sender to aid in assembling the

    fragments of a datagram.

  Flags:  3 bits

    Various Control Flags.

      Bit 0: reserved, must be zero

      Bit 1: (DF) 0 = May Fragment,  1 = Don't Fragment.

      Bit 2: (MF) 0 = Last Fragment, 1 = More Fragments.

  Fragment Offset:  13 bits

    This field indicates where in the datagram this fragment belongs.

    The fragment offset is measured in units of 8 octets (64 bits).  The

    first fragment has offset zero.

  Time to Live:  8 bits

  Protocol:  8 bits

  Header Checksum:  16 bits

  Source Address:  32 bits

  Destination Address:  32 bits

@endverbatim

@publishedAll

@released

@since v7.0

*/

	{

public:

	//

	// Basic

	//

	/**

	* Gets the minimum header length.	

	* @return Minimum header length (= 20) 

	* @since v7.0

	*/

	inline static TInt MinHeaderLength() {return 4*5; }

	/**

	* Gets the maximum header length.

	* @return Maximum header length (= 60)

	* @since v7.0

	*/

	inline static TInt MaxHeaderLength() {return 4*15; }

	/**

	* Gets a pointer to the byte following the header.

	* @return Pointer to the byte following the header

	* @since v7.0

	*/

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

	enum TOffsets

		{

		O_TotalLength = 2,

		O_FragmentOffset = 6,

		O_TTL = 8,

		O_Protocol = 9

		};

	inline TInt Version() const

		/**

		* Gets the IP version from the header.

		* @return IP version (should be 4 for IPv4)

		*/ 

		{

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

		}

	inline TInt HeaderLength() const

		/**

		* Gets the header length.

		* @return Header length in bytes (based on IHL field)

		*/

		{

		return (i[0] & 0x0f) * 4;	// Note: Returns bytes length!

		}

	inline TInt TOS() const

		/**

		* Gets the TOS from the header.

		* @return TOS

		*/

		{

		return i[1];

		}

	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 ((TOS() & 3) == 3);

		}

	inline TInt TotalLength() const

		/**

		* Gets the Total Length from the header.

		* @return Total Length (includes IP header and payload)

		*/

		{

		return (i[2] << 8) | i[3];

		}

	inline TInt Identification() const

		/**

		* Gets the Identification from the header.

		* @return Identification [0..65535]

		*/

		{

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

		}

	inline TInt Flags() const

		/**

		* Gets the Flags from the header.

		* @note returns flags byte as is, may include bits of fragment offset!

		* @return Flags

		*/

		{

		return i[6];

		}

	inline TInt DF() const

		/**

		* Gets the DF flag from the header.

		* @return DF flag (= KInet4IP_DF, if set and zero otherwise)

		*/

		{

		return i[6] & KInet4IP_DF;

		}

	inline TInt MF() const

		/**

		* Gets the MF flag from the header.

		* @return MF flag (= KInet4IP_MF, if set and zero otherwise)

		*/

		{

		return i[6] & KInet4IP_MF;

		}

	inline TInt FragmentOffset() const

		/**

		* Gets the Fragment Offset from the header.

		* @return Fragment Offset (raw 8 octet units, not a bytes offset!)

		*/

		{

		return ((i[6] & 0x1f) << 8) | i[7];

		}

	inline TInt Ttl() const

		/**

		* Gets the Time to Live from the header.

		* @return Time to Live [0..255]

		*/

		{

		return i[8];

		}

	inline TInt Protocol() const

		/**

		* Gets the Protocol from the header.

		* @return Protocol [0..255]

		*/

		{

		return i[9];

		}

	inline TInt Checksum() const

		/**

		* Gets the Header Checksum from the header.

		* @return Header Checksum (in NETWORK byte order)

		*/

		{

		// Checksum is used in network byte order

		return *((TUint16 *)&i[10]);

		}

	inline TUint32 SrcAddr() const

		/**

		* Gets the source address from the header.

		* @return Source address (in host byte order)

		*/

		{

		return (i[12] << 24) | (i[13] << 16) | (i[14] << 8) | i[15];

		}

	inline TUint32 DstAddr() const

		/**

		* Gets the destination address from the header.

		* @return Destination address (in host byte order)

		*/

		{

		return (i[16] << 24) | (i[17] << 16) | (i[18] << 8) | i[19];

		}

	inline TUint32 &SrcAddrRef() const

		/**

		* Gets a raw reference to the source address in network byte order.

		* @return Raw reference to the source address

		*/

		{

		return (TUint32 &)i[12];

		}

	inline TUint32 &DstAddrRef() const

		/**

		* Gets a raw reference to the destination address in network byte order.

		* @return Raw reference to the destination address

		*/

		{

		return (TUint32 &)i[16];

		}

	inline TPtrC8 Options() const

		/**

		* Gets the Options from the header (const overload).

		* @return Options

		*

		* @note

		*	This relies on correct value of IHL! Must not be used with

		*	corrupt headers (will panic if IHL < 5!).

		*/

		{

		// *NOTE* This includes the padding bytes, or can be empty!

		return TPtrC8((TUint8 *)&i[20], HeaderLength() - 20);

		}

	inline TPtr8 Options()

		/**

		* Gets the Options from the header.

		* @return Options

		*

		* @note

		*	This relies on correct value of IHL! Must not be used with

		*	corrupt headers (will panic if IHL < 5!).

		*/

		{

		// It is yet unclear what will be the best way to build

		// the options into the header. For the time being this

		// method returns a modifiable Ptr8 to the the available

		// option space. For this to work, the application must

		// have used the SetHeaderLength() to fix the current

		// available length.

		return TPtr8((TUint8 *)&i[20], HeaderLength() - 20);

		}

	inline void Init(TInt aTOS = 0)

		/**

		* Initialises the IPv4 header to basic initial values.

		*

		* @li	Version = 4

		* @li	IHL = 5

		* @li	Total Length = 20

		* @li	Identification = 0

		* @li	Fragment Offset = 0

		* @li	Flags = 0

		* @li	TTL = 0

		* @li	Checksum = 0

		* @li	TOS = aTOS (optional parameter, default = 0)

		*

		* However, address fields are not touched, because

		* they are most often set separately in any case.

		*

		* @param	aTOS	initial value for TOS (= 0)

		*/

		{

		i[0] = 0x45;			// Version=4, IHL=5 (= 20 bytes)

		i[1] = (TUint8)aTOS;	// TOS

		i[2] = 0;

		i[3] = 20;				// Total length = 20

		*((TInt32 *)&i[4]) = 0;	// Identification = 0, flags=0, Fragment offset = 0;

		*((TInt32 *)&i[8]) = 0;	// TTL=0,Protocol=0,Checksum=0

		}

	//

	// Build, set IP header field values into the packet

	//

	inline void SetVersion(TInt aVersion)

		/**

		* Sets the IP version in the header.

		* @param	aVersion the value to be set [0..15]

		*/

		{

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

		}

	inline void SetHeaderLength(TInt aLength)

		/**

		* Sets the header length (IHL).

		*

		* @param aLength

		*	the length of the IPv4 header in BYTES. The

		*	IHL is computed from this, without any sanity

		*	checks. The valid range is [20..60].

		*/

		{

		i[0] =  (TUint8)((i[0] & 0xf0) | ((aLength >> 2) & 0x0f));

		}

	inline void SetTOS(TInt aTos)

		/**

		* Sets the TOS in the header.

		* @param	aTos	The TOS value to set [0..255]

		*/

		{

		i[1] = (TUint8)aTos;

		}

	inline void SetTotalLength(TInt aLength)

		/**

		* Sets the Total Length in the header.

		*

		* @param	aLength the length of combined header and

		*			payload in bytes (no sanity checks, but the

		*			value should be in range [20..65535]). Only

		*			16 least significant bits used.

		*/

		{

		i[3] = (TUint8)aLength;

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

		}

	inline void SetIdentification(TInt aId)

		/**

		* Sets the Identification in the header.

		*

		* @param	aId	the value to be set (only 16 least significant

		*			bits are used, rest is ignored).

		*/

		{

		i[5] = (TUint8)aId;

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

		}

	inline void SetFlags(TUint8 aFlags)

		/**

		* Sets the Flags in the header.

		*

		* Flags are assumed to be in the three most significant bits

		* of aFlags, in their proper positions.

		* (No individual settings provided, if you need to set a flag

		* without affecting others, use Flags() to get old values,

		* update and store the result with SetFlags()).

		*

		* @param	aFlags	contains the new flags

		*/

		{

		i[6] = (TUint8)((i[6] & 0x1f) | (aFlags & 0xe0));

		}

	inline void SetFragmentOffset(TUint16 aOffset)

		/**

		* Sets the Fragment Offset in the header.

		* @param aOffset Fragment Offset (8 octet units, not in bytes)

		*/

		{

		i[6] = (TUint8)((i[6] & 0xe0) | ((aOffset >> 8) & 0x1f));

		i[7] = (TUint8)aOffset;

		}

	inline void SetTtl(TInt aTTL)

		/**

		* Sets the Time to Live in the header.

		* @param aTTL Time to Live [0..255]

		*/

		{

		i[8] = (TUint8)aTTL;

		}

	inline void SetProtocol(TInt aProtocol)

		/**

		* Sets the Protocol in the header.

		* @param aProtocol Protocol [0..255]

		*/

		{

		i[9] = (TUint8)aProtocol;

		}

	inline void SetChecksum(TInt aSum)

		/**

		* Sets the Header Checksum in the header.

		* @param aSum Header Checksum [0..65535]

		*	(16 least significant bits stored

		*	as is (assumed to be in NETWORK byte order).					

		*/

		{

		// Checksum is used in network byte order

		*((TUint16 *)&i[10]) = (TUint16)aSum;

		}

	inline void SetSrcAddr(TUint32 aAddr)

		/**

		* Sets the source address in the header.

		* @param aAddr Source address (IPv4, 32 bit integer in host byte order)

		*/

		{

		i[15] = (TUint8)aAddr;

		i[14] = (TUint8)(aAddr >> 8);

		i[13] = (TUint8)(aAddr >> 16);

		i[12] = (TUint8)(aAddr >> 24);

		}

	inline void SetDstAddr(TUint32 aAddr)

		/**

		* Sets the destination address in the header.

		* @param aAddr Destination IPv4 address (32 bit integer) in host byte order

		*/

		{

		i[19] = (TUint8)aAddr;

		i[18] = (TUint8)(aAddr >> 8);

		i[17] = (TUint8)(aAddr >> 16);

		i[16] = (TUint8)(aAddr >> 24);

		}

	//

	// The old IPv4 stack leaves IP header in packet when passing it upwards,

	// but this header is swapped into host order. As upper layers really don't

	// need this stuff much, only few "compatibility" methods is defined here

	//

	inline TInt HostHeaderLength() const

		{

		/**

		* Gets the Header Length from a header that is in Host byte order.

		* @return Header Length

		*

		* @deprecated There is no reason to use swapped headers

		*/

		return (i[3] & 0x0f) * 4;

		}

	inline TInt HostProtocol() const

		/**

		* Gets the Protocol from a header that is in Host byte order.

		* @return Protocol

		* @deprecated There is no reason to use swapped headers

		*/

		{

		return i[10];

		}

	inline void Swap()

		/**

		* Swaps the byte order in the header.

		* @deprecated There is no reason to use swapped headers

		*/

		{

		*(TUint32 *)(&i[0]) = ByteOrder::Swap32(*(TUint32 *)(&i[0]));

		*(TUint32 *)(&i[4]) = ByteOrder::Swap32(*(TUint32 *)(&i[4]));