pcpp::Layer Class Reference

#include <Layer.h>

Inheritance diagram for pcpp::Layer:

Public Member Functions
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
virtual void	parseNextLayer ()=0
virtual size_t	getHeaderLen () const =0
virtual void	computeCalculateFields ()=0
virtual std::string	toString () const =0
virtual OsiModelLayer	getOsiModelLayer () const =0

Detailed Description

Layer is the base class for all protocol layers. Each protocol supported in PcapPlusPlus has a class that inherits Layer. The protocol layer class expose all properties and methods relevant for viewing and editing protocol fields. For example: a pointer to a structured header (e.g tcphdr, iphdr, etc.), protocol header size, payload size, compute fields that can be automatically computed, print protocol data to string, etc. Each protocol instance is obviously part of a protocol stack (which construct a packet). This protocol stack is represented in PcapPlusPlus in a linked list, and each layer is an element in this list. That's why each layer has proprties to the next and previous layer in the protocol stack The Layer class, as a base class, is abstract and the user can't create an instance of it (it has a private constructor) Each layer holds a pointer to the relevant place in the packet. The layer sees all the data from this pointer forward until the end of the packet. Here is an example packet showing this concept:

====================================================
|Eth       |IPv4       |TCP       |Packet          |
|Header    |Header     |Header    |Payload         |
====================================================

|--------------------------------------------------|
EthLayer data
         |---------------------------------------|
         IPv4Layer data
                     |---------------------------|
                     TcpLayer data
                                |----------------|
                                PayloadLayer data

Constructor & Destructor Documentation

~Layer()

virtual pcpp::Layer::~Layer ( )

virtual

A destructor for this class. Frees the data if it was allocated by the layer constructor (see isAllocatedToPacket() for more info)

Member Function Documentation

computeCalculateFields()

virtual void pcpp::Layer::computeCalculateFields ( )

pure virtual

Each layer can compute field values automatically using this method. This is an abstract method

Implemented in pcpp::DhcpLayer, pcpp::IcmpLayer, pcpp::IPv4Layer, pcpp::IgmpV3ReportLayer, pcpp::SSLApplicationDataLayer, pcpp::TcpLayer, pcpp::GtpV1Layer, pcpp::SSLAlertLayer, pcpp::DnsLayer, pcpp::PPP_PPTPLayer, pcpp::IgmpV3QueryLayer, pcpp::SSLChangeCipherSpecLayer, pcpp::GREv1Layer, pcpp::SSLHandshakeLayer, pcpp::IgmpV2Layer, pcpp::RadiusLayer, pcpp::GREv0Layer, pcpp::IgmpV1Layer, pcpp::TextBasedProtocolMessage, pcpp::IPv6Layer, pcpp::EthLayer, pcpp::ArpLayer, pcpp::VlanLayer, pcpp::VxlanLayer, pcpp::MplsLayer, pcpp::SipLayer, pcpp::SllLayer, pcpp::PPPoELayer, pcpp::UdpLayer, pcpp::NullLoopbackLayer, pcpp::PacketTrailerLayer, and pcpp::PayloadLayer.

copyData()

void pcpp::Layer::copyData

(

uint8_t *

toArr

)

const

Copy the raw data of this layer to another array

Parameters

[out]

toArr

The destination byte array

getData()

uint8_t* pcpp::Layer::getData ( ) const

inline

Returns

A pointer to the layer raw data. In most cases it'll be a pointer to the first byte of the header

getDataLen()

size_t pcpp::Layer::getDataLen ( ) const

inline

Returns

The length in bytes of the data from the first byte of the header until the end of the packet

getDataPtr()

uint8_t* pcpp::Layer::getDataPtr ( size_t  offset = 0 ) const

inlinevirtual

Get a pointer to the data

Parameters

[in]

offset

Get a pointer in a certain offset. Default is 0 - get a pointer to start of data

Returns

A pointer to the data

Implements pcpp::IDataContainer.

getHeaderLen()

virtual size_t pcpp::Layer::getHeaderLen ( ) const

pure virtual

Returns

The header length in bytes

Implemented in pcpp::DhcpLayer, pcpp::IcmpLayer, pcpp::IPv4Layer, pcpp::IgmpV3ReportLayer, pcpp::TcpLayer, pcpp::GtpV1Layer, pcpp::DnsLayer, pcpp::PPP_PPTPLayer, pcpp::IgmpV3QueryLayer, pcpp::PPPoEDiscoveryLayer, pcpp::RadiusLayer, pcpp::SSLLayer, pcpp::IgmpLayer, pcpp::TextBasedProtocolMessage, pcpp::PPPoESessionLayer, pcpp::GreLayer, pcpp::IPv6Layer, pcpp::EthLayer, pcpp::VlanLayer, pcpp::VxlanLayer, pcpp::ArpLayer, pcpp::MplsLayer, pcpp::SllLayer, pcpp::UdpLayer, pcpp::NullLoopbackLayer, pcpp::PacketTrailerLayer, and pcpp::PayloadLayer.

getLayerPayload()

uint8_t* pcpp::Layer::getLayerPayload ( ) const

inline

Returns

A pointer for the layer payload, meaning the first byte after the header

getLayerPayloadSize()

size_t pcpp::Layer::getLayerPayloadSize ( ) const

inline

Returns

The size in bytes of the payload

getNextLayer()

Layer* pcpp::Layer::getNextLayer ( ) const

inline

Returns

A pointer to the next layer in the protocol stack or NULL if the layer is the last one

getOsiModelLayer()

virtual OsiModelLayer pcpp::Layer::getOsiModelLayer ( ) const

pure virtual

Returns

The OSI Model layer this protocol belongs to

Implemented in pcpp::DhcpLayer, pcpp::IcmpLayer, pcpp::IPv4Layer, pcpp::TcpLayer, pcpp::GtpV1Layer, pcpp::DnsLayer, pcpp::PPP_PPTPLayer, pcpp::RadiusLayer, pcpp::SSLLayer, pcpp::IgmpLayer, pcpp::IPv6Layer, pcpp::GreLayer, pcpp::SdpLayer, pcpp::EthLayer, pcpp::ArpLayer, pcpp::VlanLayer, pcpp::VxlanLayer, pcpp::MplsLayer, pcpp::SllLayer, pcpp::SipLayer, pcpp::PPPoELayer, pcpp::HttpMessage, pcpp::UdpLayer, pcpp::NullLoopbackLayer, pcpp::PacketTrailerLayer, and pcpp::PayloadLayer.

getPrevLayer()

Layer* pcpp::Layer::getPrevLayer ( ) const

inline

Returns

A pointer to the previous layer in the protocol stack or NULL if the layer is the first one

getProtocol()

ProtocolType pcpp::Layer::getProtocol ( ) const

inline

Returns

The protocol enum

isAllocatedToPacket()

bool pcpp::Layer::isAllocatedToPacket ( ) const

inline

Raw data in layers can come from one of sources:

1. from an existing packet - this is the case when parsing packets received from files or the network. In this case the data was already allocated by someone else, and layer only holds the pointer to the relevant place inside this data
2. when creating packets, data is allocated when layer is created. In this case the layer is responsible for freeing it as well

Returns

Returns true if the data was allocated by an external source (a packet) or false if it was allocated by the layer itself

parseNextLayer()

virtual void pcpp::Layer::parseNextLayer ( )

pure virtual

Each layer is responsible for parsing the next layer

Implemented in pcpp::DhcpLayer, pcpp::IcmpLayer, pcpp::IPv4Layer, pcpp::TcpLayer, pcpp::GtpV1Layer, pcpp::DnsLayer, pcpp::PPP_PPTPLayer, pcpp::PPPoEDiscoveryLayer, pcpp::RadiusLayer, pcpp::SSLLayer, pcpp::IgmpLayer, pcpp::TextBasedProtocolMessage, pcpp::PPPoESessionLayer, pcpp::GreLayer, pcpp::IPv6Layer, pcpp::EthLayer, pcpp::VlanLayer, pcpp::VxlanLayer, pcpp::ArpLayer, pcpp::SipLayer, pcpp::MplsLayer, pcpp::SllLayer, pcpp::UdpLayer, pcpp::NullLoopbackLayer, pcpp::PacketTrailerLayer, and pcpp::PayloadLayer.

toString()

virtual std::string pcpp::Layer::toString ( ) const

pure virtual

Returns

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

Implemented in pcpp::DhcpLayer, pcpp::IcmpLayer, pcpp::IPv4Layer, pcpp::SSLApplicationDataLayer, pcpp::HttpResponseLayer, pcpp::TcpLayer, pcpp::SipResponseLayer, pcpp::GtpV1Layer, pcpp::SSLAlertLayer, pcpp::DnsLayer, pcpp::PPP_PPTPLayer, pcpp::SSLChangeCipherSpecLayer, pcpp::PPPoEDiscoveryLayer, pcpp::GREv1Layer, pcpp::SSLHandshakeLayer, pcpp::RadiusLayer, pcpp::GREv0Layer, pcpp::IgmpLayer, pcpp::SipRequestLayer, pcpp::HttpRequestLayer, pcpp::IPv6Layer, pcpp::PPPoESessionLayer, pcpp::SdpLayer, pcpp::EthLayer, pcpp::ArpLayer, pcpp::VlanLayer, pcpp::VxlanLayer, pcpp::MplsLayer, pcpp::SllLayer, pcpp::UdpLayer, pcpp::NullLoopbackLayer, pcpp::PacketTrailerLayer, and pcpp::PayloadLayer.