whisper_library::TcpHeaderCovertChannel Class Reference

A covert channel using tcp header fields. More...

Inheritance diagram for whisper_library::TcpHeaderCovertChannel:

Public Member Functions
	TcpHeaderCovertChannel (function< void(string)> output, function< void(GenericPacket)> send)
	Constructor. More...
CovertChannel *	instance ()
void	sendMessage (string message)
void	receivePacket (GenericPacket &packet)
void	setArguments (string arguments)
	configures the covert channel More...
void	setOutput (function< void(string)> output)
	sets the output method More...
void	setSend (function< void(GenericPacket)> send)
	sets the methode used to send packets
void	initialize ()
	Initializes the covert channel. Is called after construction.
string	name () const
string	info () const
string	protocol () const
unsigned short	port () const
std::string	id () const
Public Member Functions inherited from whisper_library::CovertChannel
	CovertChannel ()
	Creates a CovertChannel.
virtual	~CovertChannel ()
	Destructor. More...
virtual void	sendMessage (std::string message)=0
	sends a message More...

Private Member Functions
vector< bitset< 3 > >	encodeMessageWithLength (string message)
void	modifyTcpPacket (TcpPacket &packet, bitset< 3 > data)
bitset< 3 >	extractData (TcpPacket &packet)

Private Attributes
vector< bitset< 3 > >	m_data_blocks
	This vector stores the bit blocks we received in the current communication.
int	m_remaining_packets
BitSetCoder< 3 >	m_coder
	The encoder/decoder we use, to split messages into bit blocks.
TcpPacketGenerator *	m_generator
	A TcpPacketGenerator acting as client used for sending messages.
function< void(string)>	m_output
	callback function pointer that is used to return received messages as a string
function< void(GenericPacket)>	m_send
	function pointer that is used to send Tcp Packets via the socket

Detailed Description

A covert channel using tcp header fields.

Covert Channel, that uses 3 bits of the TCP Header, that are not used, to hide a message. To use this class, call 'sendMessage' with your message as a string. Received packets are used to call 'receiveMessage'. The decoded message is given to the callback function 'm_output'.

Constructor & Destructor Documentation

whisper_library::TcpHeaderCovertChannel::TcpHeaderCovertChannel	(	function< void(string)>	output,
		function< void(GenericPacket)>	send
	)

Constructor.

Parameters

output	a function pointer that is called, when a complete message arrived. Its parameter is this message.
send	a function pointer that is called to send a TcpPacket via the socket.

Member Function Documentation

vector< bitset< 3 > > whisper_library::TcpHeaderCovertChannel::encodeMessageWithLength ( string  message )

private

encodeMessageWithLength splits the message into parts of 3 bits and adds length blocks inbetween.

bitset< 3 > whisper_library::TcpHeaderCovertChannel::extractData ( whisper_library::TcpPacket &  packet )

private

extractData extracts the data we hid in the packet.

string whisper_library::TcpHeaderCovertChannel::id ( ) const

virtual

Returns

the ID of the covert channel

Implements whisper_library::CovertChannel.

string whisper_library::TcpHeaderCovertChannel::info ( ) const

virtual

Returns a string with basic information about the tcp header covert channel

Implements whisper_library::CovertChannel.

CovertChannel * whisper_library::TcpHeaderCovertChannel::instance ( )

virtual

Returns

an instance of this covert channel

Implements whisper_library::CovertChannel.

void whisper_library::TcpHeaderCovertChannel::modifyTcpPacket ( whisper_library::TcpPacket &  packet, bitset< 3 >  data  )

private

modifyTcpPacket sets the reserved bits of packet to the value of data.

string whisper_library::TcpHeaderCovertChannel::name ( ) const

virtual

Returns a string with the name of the covert channel "TCP Header Covert Channel"

Implements whisper_library::CovertChannel.

unsigned short whisper_library::TcpHeaderCovertChannel::port ( ) const

virtual

Returns

the used port

Implements whisper_library::CovertChannel.

string whisper_library::TcpHeaderCovertChannel::protocol ( ) const

virtual

Returns the protocol used by this covert channel

Implements whisper_library::CovertChannel.

void whisper_library::TcpHeaderCovertChannel::receivePacket ( GenericPacket &  packet )

virtual

This function is called, when a new packet arrives at the socket. It collects them and returns the message via the callback function "m_output".

Implements whisper_library::CovertChannel.

void whisper_library::TcpHeaderCovertChannel::sendMessage

(

string

message

)

SendMessage sends a message of type string through the Tcp Header Covert Channel.

void whisper_library::TcpHeaderCovertChannel::setArguments ( string  arguments )

inlinevirtual

configures the covert channel

Parameters

arguments

Arguments that are given to the covert channel

Implements whisper_library::CovertChannel.

void whisper_library::TcpHeaderCovertChannel::setOutput ( function< void(string)>  output )

virtual

sets the output method

Parameters

output

the method the covert channel uses to output the received messages

Implements whisper_library::CovertChannel.

Member Data Documentation

int whisper_library::TcpHeaderCovertChannel::m_remaining_packets

private

Stores the number of packets, we expect to receive in the current communication. 0 means, all packets were received and the channel is ready to receive a new length packet.