keep track of the byte tags stored in a packet. More...

#include "byte-tag-list.h"

Collaboration diagram for ns3::ByteTagList:

Classes
class	Iterator
	An iterator for iterating through a byte tag list. More...

Public Member Functions
	ByteTagList ()

	ByteTagList (const ByteTagList &o)
	Copy constructor, copies the data and increases reference count.

	~ByteTagList ()

void	Add (const ByteTagList &o)

TagBuffer	Add (TypeId tid, uint32_t bufferSize, int32_t start, int32_t end)

void	AddAtEnd (int32_t appendOffset)
	Make sure that all offsets are smaller than appendOffset which represents the location where new bytes have been added to the byte buffer.

void	AddAtStart (int32_t prependOffset)
	Make sure that all offsets are bigger than prependOffset which represents the location where new bytes have been added to the byte buffer.

void	Adjust (int32_t adjustment)
	Adjust the offsets stored internally by the adjustment delta.

ByteTagList::Iterator	Begin (int32_t offsetStart, int32_t offsetEnd) const

uint32_t	Deserialize (const uint32_t *buffer, uint32_t size)
	Deserialize tag list from the provided buffer.

uint32_t	GetSerializedSize () const
	Returns number of bytes required for packet serialization.

ByteTagList &	operator= (const ByteTagList &o)
	Assignment operator, deallocates current data and assigns value of passed in ByteTagList.

void	RemoveAll ()
	Removes all of the tags from the ByteTagList.

uint32_t	Serialize (uint32_t *buffer, uint32_t maxSize) const
	Serialize the tag list into a byte buffer.

Private Member Functions
ByteTagListData *	Allocate (uint32_t size)
	Allocate the memory for the ByteTagListData.

ByteTagList::Iterator	BeginAll () const
	Returns an iterator pointing to the very first tag in this list.

void	Deallocate (ByteTagListData *data)
	Deallocates a ByteTagListData.

Private Attributes
int32_t	m_adjustment
	adjustment to byte tag offsets

ByteTagListData *	m_data
	the ByteTagListData structure

int32_t	m_maxEnd
	maximal end offset

int32_t	m_minStart
	minimal start offset

uint32_t	m_used
	the number of used bytes in the buffer

Detailed Description

keep track of the byte tags stored in a packet.

This class is mostly private to the Packet implementation and users should never have to access it directly.

Internal:: The implementation of this class is a bit tricky so, there are a couple of things to keep in mind here:

It stores all tags in a single byte buffer: each tag is stored as 4 32bit integers (TypeId, tag data size, start, end) followed by the tag data as generated by Tag::Serialize.
The struct ByteTagListData structure which contains the tag byte buffer is shared and, thus, reference-counted. This data structure is unshared as-needed to emulate COW semantics.
Each tag tags a unique set of bytes identified by the pair of offsets (start,end). These offsets are relative to the start of the packet Whenever the origin of the offset changes, the Packet adjusts all byte tags using ByteTagList::Adjust method.
When packet is reduced in size, byte tags that span outside the packet boundaries remain in ByteTagList. It is not a problem as iterator fixes the boundaries before returning item. However, when packet is extending, it calls ByteTagList::AddAtStart or ByteTagList::AddAtEnd to cut byte tags that will otherwise cover new bytes.

Definition at line 54 of file byte-tag-list.h.

Constructor & Destructor Documentation

◆ ByteTagList() [1/2]

ns3::ByteTagList::ByteTagList ( )

Definition at line 139 of file byte-tag-list.cc.

References NS_LOG_FUNCTION.

◆ ByteTagList() [2/2]

ns3::ByteTagList::ByteTagList ( const ByteTagList & o )

Copy constructor, copies the data and increases reference count.

Parameters

o	The ByteTagList to copy

Definition at line 149 of file byte-tag-list.cc.

References ns3::ByteTagListData::count, m_data, and NS_LOG_FUNCTION.

◆ ~ByteTagList()

ns3::ByteTagList::~ByteTagList ( )

Definition at line 184 of file byte-tag-list.cc.

References Deallocate(), m_data, m_used, and NS_LOG_FUNCTION.

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Member Function Documentation

◆ Add() [1/2]

void ns3::ByteTagList::Add ( const ByteTagList & o )

Parameters

o	the other list of tags to aggregate.

Aggregate the two lists of tags.

Definition at line 229 of file byte-tag-list.cc.

References Add(), BeginAll(), ns3::ByteTagList::Iterator::Item::buf, ns3::TagBuffer::CopyFrom(), ns3::ByteTagList::Iterator::Item::end, ns3::ByteTagList::Iterator::HasNext(), ns3::ByteTagList::Iterator::Next(), NS_LOG_FUNCTION, ns3::ByteTagList::Iterator::Item::size, ns3::ByteTagList::Iterator::Item::start, and ns3::ByteTagList::Iterator::Item::tid.

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◆ Add() [2/2]

TagBuffer ns3::ByteTagList::Add	(	TypeId	tid,
		uint32_t	bufferSize,
		int32_t	start,
		int32_t	end )

Parameters

tid	the typeid of the tag added
bufferSize	the size of the tag when its serialization will be completed. Typically, the return value of Tag::GetSerializedSize
start	offset which uniquely identifies the first byte tagged by this tag.
end	offset which uniquely identifies the last byte tagged by this tag.

Returns: a buffer which can be used to write the tag data.

Definition at line 193 of file byte-tag-list.cc.

References Allocate(), ns3::ByteTagListData::count, ns3::ByteTagListData::data, Deallocate(), ns3::ByteTagListData::dirty, ns3::TypeId::GetUid(), m_adjustment, m_data, m_maxEnd, m_minStart, m_used, NS_ASSERT, NS_LOG_FUNCTION, ns3::ByteTagListData::size, and ns3::TagBuffer::WriteU32().

Referenced by Add(), ns3::Packet::AddAtEnd(), and Deserialize().

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◆ AddAtEnd()

void ns3::ByteTagList::AddAtEnd ( int32_t appendOffset )

Make sure that all offsets are smaller than appendOffset which represents the location where new bytes have been added to the byte buffer.

Parameters

appendOffset maximum offset value

Definition at line 277 of file byte-tag-list.cc.

References BeginAll(), ns3::ByteTagList::Iterator::Item::buf, ns3::TagBuffer::CopyFrom(), ns3::ByteTagList::Iterator::Item::end, ns3::ByteTagList::Iterator::HasNext(), list, m_adjustment, m_maxEnd, ns3::ByteTagList::Iterator::Next(), NS_LOG_FUNCTION, ns3::ByteTagList::Iterator::Item::size, ns3::ByteTagList::Iterator::Item::start, and ns3::ByteTagList::Iterator::Item::tid.

Referenced by ns3::Packet::AddAtEnd(), ns3::Packet::AddPaddingAtEnd(), and ns3::Packet::AddTrailer().

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◆ AddAtStart()

void ns3::ByteTagList::AddAtStart ( int32_t prependOffset )

Make sure that all offsets are bigger than prependOffset which represents the location where new bytes have been added to the byte buffer.

Parameters

prependOffset minimum offset value

Definition at line 309 of file byte-tag-list.cc.

References BeginAll(), ns3::ByteTagList::Iterator::Item::buf, ns3::TagBuffer::CopyFrom(), ns3::ByteTagList::Iterator::Item::end, ns3::ByteTagList::Iterator::HasNext(), list, m_adjustment, m_minStart, ns3::ByteTagList::Iterator::Next(), NS_LOG_FUNCTION, ns3::ByteTagList::Iterator::Item::size, ns3::ByteTagList::Iterator::Item::start, and ns3::ByteTagList::Iterator::Item::tid.

Referenced by ns3::Packet::AddAtEnd(), and ns3::Packet::AddHeader().

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◆ Adjust()

void ns3::ByteTagList::Adjust ( int32_t adjustment )

inline

Adjust the offsets stored internally by the adjustment delta.

Parameters

adjustment value to change stored offsets by

Definition at line 283 of file byte-tag-list.h.

References m_adjustment.

Referenced by ns3::Packet::AddAtEnd(), ns3::Packet::AddHeader(), ns3::Packet::CreateFragment(), ns3::Packet::RemoveAtStart(), ns3::Packet::RemoveHeader(), and ns3::Packet::RemoveHeader().

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◆ Allocate()

ByteTagListData * ns3::ByteTagList::Allocate ( uint32_t size )

private

Allocate the memory for the ByteTagListData.

Parameters

size	the memory to allocate

Returns: the ByteTagListData structure

Definition at line 344 of file byte-tag-list.cc.

References data, ns3::g_freeList, ns3::g_maxSize, NS_ASSERT, and NS_LOG_FUNCTION.

Referenced by Add().

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◆ Begin()

ByteTagList::Iterator ns3::ByteTagList::Begin	(	int32_t	offsetStart,
		int32_t	offsetEnd ) const

Parameters

offsetStart	the offset which uniquely identifies the first data byte present in the byte buffer associated to this ByteTagList.
offsetEnd	the offset which uniquely identifies the last data byte present in the byte buffer associated to this ByteTagList.

Returns: an iterator

The returned iterator will allow you to loop through the set of tags present in this list: the boundaries of each tag as reported by their start and end offsets will be included within the input offsetStart and offsetEnd.

Definition at line 263 of file byte-tag-list.cc.

References ns3::ByteTagListData::data, m_adjustment, m_data, m_used, and NS_LOG_FUNCTION.

Referenced by BeginAll(), and ns3::Packet::GetByteTagIterator().

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