messageProcessor
Class ReplayDetection

java.lang.Object
  messageProcessor.ReplayDetection

 class ReplayDetection
extends java.lang.Object

Detects whether a message has already been processed, or not. Detection is done using timestamps and hash tables.

This class is thread-safe (but parallel execution won't increase performance).

Author:

Karl-Peter Fuchs

Field Summary

private static NetworkClockController	clock Reference on component NetworkClock used to validate timestamps.
private float	DB_LOAD_FACTOR The load factor for the hash tables replayDatabase1 and replayDatabase2.
private int	INITIAL_DB_CAPACITY Number of items the database for replay detection should approximately hold.
private static InternalInformationPortController	internalInformationPort Reference on InternalInformationPort.
private long	lastDBSwitch Point of time, the databases were switched (and one got replaced) lastly.
private static java.util.logging.Logger	LOGGER Logger used to log and display information.
private long	MAX_DELAY Time after which a message is considered as out of date in ms.
private java.util.Hashtable<java.lang.Integer,byte[]>	replayDatabase1 First replay database.
private java.util.Hashtable<java.lang.Integer,byte[]>	replayDatabase2 Second replay database.
private long	TOLERANCE Maximum divergence between mix' and client's clock in ms.
private boolean	writeToDB1 Indicates weather to write in the first or second replay database.

Constructor Summary

protected

ReplayDetection() Loads values from property file and initializes hash tables.

Method Summary

private boolean	isAlreadyInDB(java.lang.Integer key, byte[] value) Detects whether a key is in one of the databases or not.
protected boolean	isReplay(BasicMessage basicMessage) Detects whether a message has already been processed, or not.
private boolean	isReplay(java.lang.Integer key, byte[] value, long timestamp) Detects whether a message has already been processed, or not.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

internalInformationPort

private static InternalInformationPortController internalInformationPort

Reference on InternalInformationPort. Used to display and/or log data and read general settings.

LOGGER

private static final java.util.logging.Logger LOGGER

Logger used to log and display information.

clock

private static NetworkClockController clock

Reference on component NetworkClock used to validate timestamps.

INITIAL_DB_CAPACITY

private final int INITIAL_DB_CAPACITY

Number of items the database for replay detection should approximately hold.

DB_LOAD_FACTOR

private final float DB_LOAD_FACTOR

The load factor for the hash tables replayDatabase1 and replayDatabase2.

TOLERANCE

private final long TOLERANCE

Maximum divergence between mix' and client's clock in ms.

MAX_DELAY

private final long MAX_DELAY

Time after which a message is considered as out of date in ms.

replayDatabase1

private java.util.Hashtable<java.lang.Integer,byte[]> replayDatabase1

First replay database.

replayDatabase2

private java.util.Hashtable<java.lang.Integer,byte[]> replayDatabase2

Second replay database.

lastDBSwitch

private long lastDBSwitch

Point of time, the databases were switched (and one got replaced) lastly.

writeToDB1

private boolean writeToDB1

Indicates weather to write in the first or second replay database.

Constructor Detail

ReplayDetection

protected ReplayDetection()

Loads values from property file and initializes hash tables.

Method Detail

isReplay

protected boolean isReplay(BasicMessage basicMessage)

Detects whether a message has already been processed, or not. Detection is done using timestamps and hash tables.

Parameters:

basicMessage - The message to be checked.

Returns:

Indicates whether the bypasses message is a replay or not.

isReplay

private boolean isReplay(java.lang.Integer key,
                         byte[] value,
                         long timestamp)

Detects whether a message has already been processed, or not. Detection is done using timestamps and hash tables.

Parameters:

key - The message's key in the hash table.

value - The message's value in the hash table.

timestamp - The message's timestamp.

Returns:

Indicates whether the bypasses message is a replay or not.

isAlreadyInDB

private boolean isAlreadyInDB(java.lang.Integer key,
                              byte[] value)

Detects whether a key is in one of the databases or not.

Parameters:

key - The key to be checked.

Returns:

Indicates whether the bypasses key is in one of the databases or not