pcpp::PacketTrailerLayer Class Reference

#include <PacketTrailerLayer.h>

Inheritance diagram for pcpp::PacketTrailerLayer:

Public Member Functions
	PacketTrailerLayer (uint8_t *data, size_t dataLen, Layer *prevLayer, Packet *packet)
uint8_t *	getTrailerData () const
std::string	getTrailerDataAsHexString () const
size_t	getTrailerLen () const
void	parseNextLayer ()
size_t	getHeaderLen () const
void	computeCalculateFields ()
std::string	toString () const
OsiModelLayer	getOsiModelLayer () const
Public Member Functions inherited from pcpp::Layer
virtual	~Layer ()
Layer *	getNextLayer () const
Layer *	getPrevLayer () const
ProtocolType	getProtocol () const
uint8_t *	getData () const
size_t	getDataLen () const
uint8_t *	getLayerPayload () const
size_t	getLayerPayloadSize () const
bool	isAllocatedToPacket () const
void	copyData (uint8_t *toArr) const
uint8_t *	getDataPtr (size_t offset=0) const

Detailed Description

A class for representing packet tailer (a.k.a footer or padding) which refers to supplemental data placed at the end of a block of data being stored or transmitted, which may contain information for the handling of the data block, or just mark its end (taken from Wikipedia: https://en.wikipedia.org/wiki/Trailer_(computing) )

There are various reasons for adding a packet trailer, one of the most famous is FCS (Frame check sequence) which refers to the extra error-detecting code added to a frame. Another usage is padding which means adding data to reach a minimum required packet length.

Although this layer inherits from the Layer class, it is not a standard layer in the sense that it can't be constructed by the user. This layer may be only be constructed in the Packet class, in the process of parsing the packet and creating the layers; if at the end of the parsing process there is data left that is not allocated to any layer, it's assumed to be the packet trailer and an instance of this class is created. This means this layer can only exist as the last layer in a packet, if a packet trailer indeed exists.

No layer can be added by the user after this layer (trying to do that will result with an error).

This layer can be removed by the user or extended/shortened, as any layer.

It also contains method to extract the trailer data

Constructor & Destructor Documentation

PacketTrailerLayer()

pcpp::PacketTrailerLayer::PacketTrailerLayer ( uint8_t *  data, size_t  dataLen, Layer *  prevLayer, Packet *  packet  )

inline

A constructor that creates the layer from an existing packet raw data

Parameters

[in]	data	A pointer to the raw data
[in]	dataLen	Size of the data in bytes
[in]	prevLayer	A pointer to the previous layer
[in]	packet	A pointer to the Packet instance where layer will be stored in

Member Function Documentation

computeCalculateFields()

void pcpp::PacketTrailerLayer::computeCalculateFields ( )

inlinevirtual

Does nothing for this layer

Implements pcpp::Layer.

getHeaderLen()

size_t pcpp::PacketTrailerLayer::getHeaderLen ( ) const

inlinevirtual

Returns

trailer data length in bytes

Implements pcpp::Layer.

getOsiModelLayer()

OsiModelLayer pcpp::PacketTrailerLayer::getOsiModelLayer ( ) const

inlinevirtual

Returns

The OSI Model layer this protocol belongs to

Implements pcpp::Layer.

getTrailerData()

uint8_t* pcpp::PacketTrailerLayer::getTrailerData ( ) const

inline

Get a pointer to the trailer data

Returns

A pointer to the trailer data

getTrailerDataAsHexString()

std::string pcpp::PacketTrailerLayer::getTrailerDataAsHexString

(

)

const

Returns

Trailer data as hex string

getTrailerLen()

size_t pcpp::PacketTrailerLayer::getTrailerLen ( ) const

inline

Get the trailer data length

Returns

The trailer data length in bytes

parseNextLayer()

void pcpp::PacketTrailerLayer::parseNextLayer ( )

inlinevirtual

Does nothing for this layer (PacketTrailerLayer is always last)

Implements pcpp::Layer.

toString()

std::string pcpp::PacketTrailerLayer::toString ( ) const

virtual

Returns

A string representation of the layer most important data (should look like the layer description in Wireshark)

Implements pcpp::Layer.