cattp

package module
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 Go to latest Published: Jun 17, 2015 License: BSD-3-Clause Imports: 11 Imported by: 0

README

CAT_TP

CAT_TP is a golang package implementing a CAT_TP protocol layer for both, client and server side applications. The decoding of CAT_TP packets from a PCAP stream is also supported.

##Specification:

This implementation has been built based on the ETSI specification and makes heavy use of this libpcap wrapper by miekg. Thanks !

Documentation:

Is available at at godoc.org.

TODO

  • Deal with MaxSDU and MaxPDU size from SYN packet.
  • Implement CAT_TP port allocation. Currently source and destination ports must be specified explicitly.
  • Add callback hooks for connection states.
  • Implement tcpdump like command line util

Documentation

Index

Examples

Constants

View Source 
const (
	UNK     = iota
	SYN     = iota
	SYNACK  = iota
	ACK     = iota
	RST     = iota
	DATAACK = iota
	NUL     = iota
	EAK     = iota
)
View Source 
const (
	FLAG_MASK = 0xFC
	SYN_FLAG  = 0x80
	ACK_FLAG  = 0x40
	EAK_FLAG  = 0x20
	RST_FLAG  = 0x10
	NUL_FLAG  = 0x08
	SEG_FLAG  = 0x04
)
View Source 
const (
	BASE_HLEN = 18
	SYN_HLEN  = 5
)
View Source 
const (
	DefaultMaxPDUSize  = 1024
	DefaultMaxSDUSize  = 512
	DefaultSrcPort     = 1
	DefaultDestPort    = 9000
	DefaultWindowSize  = 10
	MaxHeaderLen       = 255
	MaxIdenficationLen = MaxHeaderLen - (BASE_HLEN + 4 + 1)
	MaxEAKs            = 118 /*(MaxHederLen - (BASE_HLEN))/2 */
)
View Source 
const (
	CLOSE     = iota
	LISTEN    = iota
	SYNRCVD   = iota
	OPEN      = iota
	CLOSEWAIT = iota
	SYNSENT   = iota
)

Connection states

View Source 
const (
	CONNECTION_HANDLER = iota
	RECEIVEWINDOW_SIZE = iota
	IDENTIFICATION     = iota
)

Socket parameter

View Source 
const (
	LOGPREFIX = "CATTP"
)

Variables

View Source 
var CLOSEWAITTimeout time.Duration = 1 * time.Second
View Source 
var Log *log.Logger
View Source 
var RetransmitCount int = 2

RetransmitCount is a configurable value to specify the amount of retries that will be performed until a connection is considered to be disconnected.

View Source 
var RetransmitTimeout time.Duration = 2 * time.Second

Functions

func BufferHandler 

func BufferHandler(c *Connection, ps []*Header, data []byte)

BufferHandler is the default handler that pushes all incoming data to the corresponding buffer. This data can be read by using the io.Reader interface accordingly.

func EchoHandler 

func EchoHandler(c *Connection, ps []*Header, data []byte)

EchoHandler is a default handler that just prints the payload to stdout.

func IgnoreHandler 

func IgnoreHandler(c *Connection, ps []*Header, data []byte)

IgnoreHandler ignoresincoming bytes

func KeepListening 

func KeepListening(as string, lport uint16, handler Handler, params ...SocketParameters) (err error)

Listen starts a CAT_TP server synchronously. It will block until the server is in state CLOSED.

func LogHandler 

func LogHandler(c *Connection, ps []*Header, data []byte)

LogHandler logs the packet structure to the logging framework.

func NewSeqNo 

func NewSeqNo() uint16

func Nibble 

func Nibble(data []byte) []byte

switches the byte array per nibble (like big to little endian just with nibbles)

Types

type Connection 

type Connection struct {
	// contains filtered or unexported fields
}

Connection represents a CAT_TP connection.

func Connect 

func Connect(addr string, lport, rport uint16, id []byte, handler Handler, params ...SocketParameters) (con *Connection, err error)

Connect tries to connect to a remote CAT_TP server. It is not blocking.

func ConnectWait 

func ConnectWait(addr string, lport, rport uint16, id []byte, handler Handler, params ...SocketParameters) (con *Connection, err error)

ConnectWait is a convenient function for a blocking connect.

func NewConnection 

func NewConnection(lport, rport uint16) (con *Connection)

NewConnection creates a new empty Connection object.

func (*Connection) Close 

func (c *Connection) Close() (err error)

Close gracefully closes a CAT_TP connection.

func (*Connection) Identification 

func (c *Connection) Identification() []byte

func (*Connection) Kill 

func (con *Connection) Kill()

Kill closes a client connection immediately.

func (*Connection) LocalAddr 

func (c *Connection) LocalAddr() net.Addr

func (*Connection) LocalPort 

func (c *Connection) LocalPort() uint16

func (*Connection) RCV_CUR_SEQ_NB 

func (c *Connection) RCV_CUR_SEQ_NB() uint16

This is the sequence number of the next PDU that is to be sent.

func (*Connection) RCV_INI_SEQ_NB 

func (c *Connection) RCV_INI_SEQ_NB() uint16

This is the initial sequence number for the sending activity. This shall be the sequence number that was previously sent in the SYN PDU.

func (*Connection) RCV_OUT_OF_SEQ_PDU_SEQ_NB 

func (c *Connection) RCV_OUT_OF_SEQ_PDU_SEQ_NB() uint16

This is the sequence numbers that have been received out of sequence.

func (*Connection) RCV_PDU_SIZE_MAX 

func (c *Connection) RCV_PDU_SIZE_MAX() uint16

This is the largest PDU size that may be sent.

func (*Connection) RCV_SDU_SIZE_MAX 

func (c *Connection) RCV_SDU_SIZE_MAX() uint16

This is the largest SDU size that may be sent.

func (*Connection) RCV_WIN_SIZE 

func (c *Connection) RCV_WIN_SIZE() uint16

This is the number of PDUs that can be received, counting from SND_UNA_PDU_SEQ_NB-1.

func (*Connection) Read 

func (c *Connection) Read(b []byte) (co int, err error)

Read reads bytes from a connection. The Buffer handler must have been used to make this working.

func (*Connection) RemoteAddr 

func (c *Connection) RemoteAddr() *net.UDPAddr

func (*Connection) RemotePort 

func (c *Connection) RemotePort() uint16

func (*Connection) SND_INI_SEQ_NB 

func (c *Connection) SND_INI_SEQ_NB() uint16

This is the initial sequence number for the sending activity. This shall be the sequence number that was previously sent in the SYN PDU.

func (*Connection) SND_NXT_SEQ_NB 

func (c *Connection) SND_NXT_SEQ_NB() uint16

This is the sequence number of the next PDU that is to be sent.

func (*Connection) SND_PDU_SIZE_MAX 

func (c *Connection) SND_PDU_SIZE_MAX() uint16

This is the largest PDU size that may be sent.

func (*Connection) SND_SDU_SIZE_MAX 

func (c *Connection) SND_SDU_SIZE_MAX() uint16

This is the largest SDU size that may be sent.

func (*Connection) SND_UNA_PDU_SEQ_NB 

func (c *Connection) SND_UNA_PDU_SEQ_NB() uint16

This is the sequence number of the oldest unacknowledged PDU that was sent. If all sent PDUs were acknowledged, it is equal to the sequence number of the next PDU that is to be sent (SND_NXT_SEQ_NB).

func (*Connection) SND_WIN_SIZE 

func (c *Connection) SND_WIN_SIZE() uint16

This is the number of PDUs that can be received, counting from SND_UNA_PDU_SEQ_NB-1.

func (*Connection) Send 

func (c *Connection) Send(h *Header) (err error)

Send is an exported method to manually send individual packets. It is intended to be used for testing scenarios and debugging only.

func (*Connection) StateS 

func (c *Connection) StateS() (ret string)

StateS returns the current state of the connection in human readable form.

func (*Connection) WaitForClose 

func (con *Connection) WaitForClose() error

WaitForClose block until the connection is in state CLOSED.

func (*Connection) WaitForConnect 

func (con *Connection) WaitForConnect() error

WaitForConnect blocks until the connection is established or the connection failed.

func (*Connection) Write 

func (c *Connection) Write(b []byte) (co int, err error)

Write sends a sequence of bytes to the CAT_TP connection.

type ConnectionHandler 

type ConnectionHandler func(c *Connection)

ConnectionHandler is the callback type for an incoming connection.

type Dumper 

type Dumper interface {
	Dump(data []byte) string
}
var OctetDumper Dumper = HexDumper{}

type Handler 

type Handler func(c *Connection, ps []*Header, data []byte)

Handler is the callback type for incoming data (on both sides) 

type Header struct {
	// contains filtered or unexported fields
}

func New 

func New(flags, version byte, srcport, destport, seq, ack, wsize, datlen uint16) (ret *Header)

func NewACK 

func NewACK(p *Header, seqno, wsize uint16) *Header

func NewDataACK 

func NewDataACK(version byte, srcport, destport, seqno, ackno, wsize uint16, data []byte) (ret *Header)

func NewHeader 

func NewHeader(raw []byte) (ret *Header, err error)

NewHeader creates a new cattp packet based on an existing pcap packet. Error is returned if the pcap packet is not a cattp packet.

func NewNUL 

func NewNUL(version byte, srcport, destport, seq, ack, wsize uint16) *Header

func NewRST 

func NewRST(version byte, srcport, destport, seq, ack uint16, rc byte) (ret *Header)

func NewSYN 

func NewSYN(version byte, srcport, destport, wsize, maxpdusize, maxsdusize uint16, identification []byte) (ret *Header)

func NewSYNACK 

func NewSYNACK(syn *Header, wsize, maxpdusize, maxsdusize uint16, ids ...[]byte) (ret *Header)

func (*Header) ACK 

func (p *Header) ACK() bool

func (*Header) AckNo 

func (p *Header) AckNo() uint16

func (*Header) BinaryString 

func (p *Header) BinaryString(mc ...int) string

func (*Header) CheckSum 

func (p *Header) CheckSum() uint16

func (*Header) DataLen 

func (p *Header) DataLen() uint16

func (*Header) DestPort 

func (p *Header) DestPort() uint16

func (*Header) EAK 

func (p *Header) EAK() bool

func (*Header) ExtendedAcks 

func (p *Header) ExtendedAcks() []uint16

func (*Header) FlagString 

func (p *Header) FlagString() string

func (*Header) Flags 

func (p *Header) Flags() byte

func (*Header) HashString 

func (p *Header) HashString() string

HashString returns a hash over the entire cattp packet (udp payload)

func (*Header) HeaderLen 

func (p *Header) HeaderLen() uint8

func (*Header) Identification 

func (p *Header) Identification() []byte

func (*Header) IdentificationLen 

func (p *Header) IdentificationLen() byte

func (*Header) MaxPDUSize 

func (p *Header) MaxPDUSize() uint16

func (*Header) MaxSDUSize 

func (p *Header) MaxSDUSize() uint16

func (*Header) NUL 

func (p *Header) NUL() bool

func (*Header) NeedsAck 

func (p *Header) NeedsAck() bool

func (*Header) Payload 

func (p *Header) Payload() []byte

func (*Header) RST 

func (p *Header) RST() bool

func (*Header) Raw 

func (p *Header) Raw() []byte

func (*Header) ReasonCode 

func (p *Header) ReasonCode() byte

func (*Header) ReasonString 

func (p *Header) ReasonString() string

ReasonString returns a human readable message for the reason code of the RST packet.

func (*Header) SEG 

func (p *Header) SEG() bool

func (*Header) SYN 

func (p *Header) SYN() bool

func (*Header) SeqNo 

func (p *Header) SeqNo() uint16

func (*Header) SetEAK 

func (p *Header) SetEAK(eaks []uint16) error

func (*Header) SrcPort 

func (p *Header) SrcPort() uint16

func (*Header) String 

func (p *Header) String() string

func (*Header) SupportsEAK 

func (p *Header) SupportsEAK() bool

func (*Header) TotalLen 

func (p *Header) TotalLen() int

func (*Header) Type 

func (p *Header) Type() int

func (*Header) TypeS 

func (p *Header) TypeS() (ret string)

func (*Header) TypeString 

func (p *Header) TypeString() string

func (*Header) UpdateCheckSum 

func (p *Header) UpdateCheckSum()

func (*Header) Version 

func (p *Header) Version() byte

func (*Header) WindowSize 

func (p *Header) WindowSize() uint16

type HexDumper 

type HexDumper struct{}

func (HexDumper) Dump 

func (h HexDumper) Dump(data []byte) string

type ParameterKey 

type ParameterKey int

type ParameterValue 

type ParameterValue interface{}

type ReceiveWindow 

type ReceiveWindow struct {
	// contains filtered or unexported fields
}

ReceiveWindow keeps track of the incoming sequence. Out of sequence packets will be stored and only returned in the correct sequence.

func NewReceiveWindow 

func NewReceiveWindow(inorder uint16, size uint16) *ReceiveWindow

NewReceiveWindow initializes a new receive window.

func (*ReceiveWindow) Receive 

func (s *ReceiveWindow) Receive(h *Header) (ret []*Header, err error)

Receive takes a packet and checks whether it is out of sequence. If not it will be sorted and an array of in-sequence-packets will be returned. This array is empty if no in-sequence packets are available.

func (*ReceiveWindow) Used 

func (s *ReceiveWindow) Used() uint16

Used returns the amount of packets that remain in the receive window.

func (*ReceiveWindow) WindowSize 

func (s *ReceiveWindow) WindowSize() uint16

WindowSize determines the space that is left in the receive window. It is used to set the window size in each sent packet.

type SendWindow 

type SendWindow struct {
	// contains filtered or unexported fields
}

SendWindow keeps track of which sent packets have been acknowledged or not. Acknowledged packets are removed from the window and others could be retransmitted.

func NewSendWindow 

func NewSendWindow(last uint16, size uint16) *SendWindow

NewSendWindow initializes a sending window.

func (*SendWindow) Ack 

func (c *SendWindow) Ack(h *Header) error

Ack acknowledges an incoming packet. If the packet with the acknowledged sequence number is in the sending window, it will be removed

func (*SendWindow) Add 

func (s *SendWindow) Add(h *Header) *sendTimeout

Add adds a packet to the sent window once it was sent.

func (*SendWindow) Get 

func (s *SendWindow) Get(sn uint16) *Header

Get returns a packet from the sending window based in its sequence number.

type Server 

type Server struct {
	// contains filtered or unexported fields
}

Server represents a listen server (UDP) that accepts client connections.

Example 
//A simple echo server
server, err := Listen("localhost:8770", 9000,
	func(c *Connection, h []*Header, data []byte) {
		c.Write(data)
	})

if err != nil {
	Log.Fatalf("Could not create listen server: %s", err)
}

client, err := ConnectWait("localhost:8770", 1, 9000, []byte{},
	func(c *Connection, h []*Header, data []byte) {
		fmt.Printf("%s", string(data))
	})

if err != nil {
	Log.Fatalf("Could not connect to server: %s", err)
}

client.Write([]byte("Hello World!"))

time.Sleep(200 * time.Millisecond)

client.Close()
server.CloseWait()

Output:

Hello World!

func Listen 

func Listen(as string, lport uint16, handler Handler, params ...SocketParameters) (srv *Server, err error)

Listen starts a CAT_TP server asynchronously.

func (*Server) Close 

func (s *Server) Close() (err error)

Close gracefully closes a listen socket.

func (*Server) CloseWait 

func (s *Server) CloseWait() error

CloseWait is a convenience method for a blocking Close().

func (*Server) Kill 

func (srv *Server) Kill(clients bool)

Kill closes server connection immediately.

func (*Server) SetListener 

func (srv *Server) SetListener(lport uint16, handler Handler, params ...SocketParameters) *Server

SetListener adds another CATTP port Listener to an existing UDP server socket. This functon can be used to listen to multiple CATTP ports on a single UDP server socket.

func (*Server) Wait 

func (s *Server) Wait() error

Wait blocks until the listen socket is closed. This includes all open client connections.

type SocketParameters 

type SocketParameters map[ParameterKey]ParameterValue

Source Files

View all Source files

Directories

Path Synopsis
cattptrace

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