org.opendaylight.openflowplugin.libraries.liblldp

Class Packet

java.lang.Object

org.opendaylight.openflowplugin.libraries.liblldp.Packet

Direct Known Subclasses:

Ethernet, LLDP, LLDPTLV

public abstract class Packet
extends Object

Abstract class which represents the generic network packet object. It provides the basic methods which are common for all the packets, like serialize and deserialize.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	corrupted
protected Map<String,org.apache.commons.lang3.tuple.Pair<Integer,Integer>>	hdrFieldCoordMap
protected Map<String,byte[]>	hdrFieldsMap
protected static org.slf4j.Logger	LOG
protected Packet	parent
protected Packet	payload
protected Class<? extends Packet>	payloadClass
protected byte[]	rawPayload
protected boolean	writeAccess

Constructor Summary

Constructors

Constructor and Description
Packet()
Packet(boolean writeAccess)

Method Summary

Modifier and Type	Method and Description
Packet	deserialize(byte[] data, int bitOffset, int size) This method deserializes the data bits obtained from the wire into the respective header and payload which are of type Packet.
boolean	equals(Object obj)
int	getfieldnumBits(String fieldName) This method fetches the number of bits for header field specified by 'fieldname'.
int	getfieldOffset(String fieldName) This method fetches the start bit offset for header field specified by 'fieldname'.
int	getHeaderSize() Gets the header length in bits.
Packet	getParent()
Packet	getPayload()
byte[]	getRawPayload() Returns the raw payload carried by this packet in case payload was not parsed.
int	hashCode()
boolean	isCorrupted() Return whether the deserialized packet is to be considered corrupted.
protected void	postDeserializeCustomOperation(byte[] data, int startBitOffset) This method re-computes the checksum of the bits received on the wire and validates it with the checksum in the bits received Since the computation of checksum varies based on the protocol, this method is overridden.
protected void	postSerializeCustomOperation(byte[] myBytes) This method gets called at the end of the serialization process It is intended for the child packets to insert some custom data into the output byte stream which cannot be done or cannot be done efficiently during the normal Packet.serialize() path.
byte[]	serialize() This method serializes the header and payload from the respective packet class, into a single stream of bytes to be sent on the wire.
void	setHeaderField(String headerField, byte[] readValue)
void	setParent(Packet parent)
void	setPayload(Packet payload)
void	setRawPayload(byte[] bytes) Set a raw payload in the packet class.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

LOG

protected static final org.slf4j.Logger LOG

writeAccess

protected boolean writeAccess

corrupted

protected boolean corrupted

parent

protected Packet parent

payload

protected Packet payload

rawPayload

protected byte[] rawPayload

hdrFieldCoordMap

protected Map<String,org.apache.commons.lang3.tuple.Pair<Integer,Integer>> hdrFieldCoordMap

hdrFieldsMap

protected Map<String,byte[]> hdrFieldsMap

payloadClass

protected Class<? extends Packet> payloadClass

Constructor Detail

Packet

public Packet()

Packet

public Packet(boolean writeAccess)

Method Detail

getParent

public Packet getParent()

getPayload

public Packet getPayload()

setParent

public void setParent(Packet parent)

setPayload

public void setPayload(Packet payload)

setHeaderField

public void setHeaderField(String headerField,
                           byte[] readValue)

deserialize

public Packet deserialize(byte[] data,
                          int bitOffset,
                          int size)
                   throws PacketException

This method deserializes the data bits obtained from the wire into the respective header and payload which are of type Packet.

Parameters:

data - - data from wire to deserialize

bitOffset - bit position where packet header starts in data array

size - size of packet in bits

Returns:

Packet

Throws:

PacketException - if deserialization fails

serialize

public byte[] serialize()
                 throws PacketException

This method serializes the header and payload from the respective packet class, into a single stream of bytes to be sent on the wire.

Returns:

The byte array representing the serialized Packet

Throws:

PacketException - if serialization fails

postSerializeCustomOperation

protected void postSerializeCustomOperation(byte[] myBytes)
                                     throws PacketException

This method gets called at the end of the serialization process It is intended for the child packets to insert some custom data into the output byte stream which cannot be done or cannot be done efficiently during the normal Packet.serialize() path. An example is the checksum computation for IPv4

Parameters:

myBytes - serialized bytes

Throws:

PacketException - on failure

postDeserializeCustomOperation

protected void postDeserializeCustomOperation(byte[] data,
                                              int startBitOffset)
                                       throws PacketException

This method re-computes the checksum of the bits received on the wire and validates it with the checksum in the bits received Since the computation of checksum varies based on the protocol, this method is overridden. Currently only IPv4 and ICMP do checksum computation and validation. TCP and UDP need to implement these if required.

Parameters:

data - The byte stream representing the Ethernet frame

startBitOffset - The bit offset from where the byte array corresponding to this Packet starts in the frame

Throws:

PacketException - on failure

getHeaderSize

public int getHeaderSize()

Gets the header length in bits.

Returns:

int the header length in bits

getfieldOffset

public int getfieldOffset(String fieldName)

This method fetches the start bit offset for header field specified by 'fieldname'. The offset is present in the hdrFieldCoordMap of the respective packet class

Returns:

Integer - startOffset of the requested field

getfieldnumBits

public int getfieldnumBits(String fieldName)

This method fetches the number of bits for header field specified by 'fieldname'. The numBits are present in the hdrFieldCoordMap of the respective packet class

Returns:

Integer - number of bits of the requested field

toString

public String toString()

Overrides:

toString in class Object

getRawPayload

public byte[] getRawPayload()

Returns the raw payload carried by this packet in case payload was not parsed. Caller can call this function in case the getPaylod() returns null.

Returns:

The raw payload if not parsable as an array of bytes, null otherwise

setRawPayload

public void setRawPayload(byte[] bytes)

Set a raw payload in the packet class.

Parameters:

bytes - The raw payload as byte array

isCorrupted

public boolean isCorrupted()

Return whether the deserialized packet is to be considered corrupted. This is the case when the checksum computed after reconstructing the packet received from wire is not equal to the checksum read from the stream. For the Packet class which do not have a checksum field, this function will always return false.

Returns:

true if the deserialized packet's recomputed checksum is not equal to the packet carried checksum

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object