com.rsa.ace.techservice.udpserver
Class AcePacketTrailer

java.lang.Object
  com.rsa.ace.techservice.udpserver.AcePacketTrailer

public class AcePacketTrailer
extends java.lang.Object

This is a packet trailer parsing/building helper class. This is used by both requests and responses for trailer processing. It implements methods associated with processing nonce and packet CRC calculations.

Constructor Summary

AcePacketTrailer()
Constructs an AcePacketTrailer which nonce will be initialized

AcePacketTrailer(byte[] nonce)
Constructs a default AcePacketTrailer.

AcePacketTrailer(java.nio.ByteBuffer buf)
Constructs an AcePacketTrailer reading bytes from the stream passed.

Method Summary

boolean	addNonce(java.nio.ByteBuffer respBuf) Adds the nonce portion of the AcePacketTrailer to the buffer passed.
int	calculateCRC(byte[] crcData, int crcDataOffset, int crcDataLength) Calculates the Cyclic Redundacy Check value for the trailer.
int	getCRC() This returns the Cyclic Redundacy Check value from the trailer.
byte[]	getNonce() This returns the nonce.
int	getSize()
java.lang.String	toString() Converts the AcePacketTrailer to a string.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AcePacketTrailer

public AcePacketTrailer(byte[] nonce)
                 throws AcePacketException

Constructs a default AcePacketTrailer.

Parameters:

nonce - A request from which the nonce is taken. This may be null.

cyclicRedundancyCheck - The CRC for the trailer.

Throws:

AcePacketException - If the nonce is not the correct length.

AcePacketTrailer

public AcePacketTrailer(java.nio.ByteBuffer buf)
                 throws AcePacketException

Constructs an AcePacketTrailer reading bytes from the stream passed.

Parameters:

buf - The byte-buffer from which the header is initialized.

Throws:

AcePacketException - If the nonce is not the correct length or this is unable to get the nonce and CRC values.

AcePacketTrailer

public AcePacketTrailer()
                 throws AcePacketException

Constructs an AcePacketTrailer which nonce will be initialized

Throws:

AcePacketException

Method Detail

getNonce

public byte[] getNonce()

This returns the nonce.

Returns:

The nonce bytes.

getCRC

public int getCRC()

This returns the Cyclic Redundacy Check value from the trailer.

Returns:

The CRC.

addNonce

public boolean addNonce(java.nio.ByteBuffer respBuf)
                 throws AcePacketException

Adds the nonce portion of the AcePacketTrailer to the buffer passed. This does nothing if the original request did not have a trailer w/ nonce.

Parameters:

respBuf - The byte-buffer to which the nonce is written.

Returns:

true if a nonce was added, false if a nonce was not added.

Throws:

AcePacketException - If an error occurs adding the nonce.

calculateCRC

public int calculateCRC(byte[] crcData,
                        int crcDataOffset,
                        int crcDataLength)

Calculates the Cyclic Redundacy Check value for the trailer. Taken from a5_crc_algor.c in the 'ct_ace_base' VOB.

Parameters:

crcData - The data to be CRC'd. This should include the nonce.

crcDataOffset - The offset at which CRC calculation will start.

cdcDataLength - The number of bytes to be CRC'ed.

Returns:

The CRC for the data.

getSize

public int getSize()

toString

public java.lang.String toString()

Converts the AcePacketTrailer to a string.

Overrides:

toString in class java.lang.Object

Returns:

A String representation of the trailer.