inputOutputHandler
Class PreviousMixConnectionHandler

java.lang.Object
  java.lang.Thread
      inputOutputHandler.PreviousMixConnectionHandler

All Implemented Interfaces:

java.lang.Runnable

final class PreviousMixConnectionHandler
extends java.lang.Thread

Handles communication with a previous mix (in the same cascade as this one). Waits for the previous mix to establish a permanent (TCP) connection, which is used to transmit the messages (Requests and Replyies) of all users connected to the cascade's fist mix (multiplex channel). (De-)multiplexes Requests/Replyies using an (encrypted) header (see addInterMixHeader()).

Note: Authentication is NOT implemented!

Author:

Karl-Peter Fuchs

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

private java.net.InetAddress	BIND_ADDRESS Address this PreviousMixConnectionHandler's socket shall be bound to.
private ExternalInformationPortController	externalInformationPort Reference on component ExternalInformationPort (Used to provide the cryptographic key used to encrypt/decrypt multiplex-headers to the previous mix.
private java.util.concurrent.atomic.AtomicBoolean	handleRepliesIsWaitingForConnection Indicates that method handleReplies() wants to send replies (to the previous mix), but the connection is lost (Used for synchronization, when connection is established again).
private InputOutputHandlerController	inputOutputHandler Reference on InputOutputHandlerController() (Used to get processed replies and add unprocessed requests).
private int	INTER_MIX_BLOCK_SIZE Block size of the cryptographic algorithm used to encrypt the multiplex-header.
private javax.crypto.Cipher	interMixDecryptCipherWithPreviousMix Cipher for decrypting multiplex-headers of requests.
private javax.crypto.Cipher	interMixEncryptCipherWithPreviousMix Cipher for encrypting multiplex-headers of replies.
private javax.crypto.spec.IvParameterSpec	interMixIVWithPreviousMix Initialization vector used to encrypt data between this mix and its predecessor.
private javax.crypto.SecretKey	interMixKeyWithPreviousMix Key used to encrypt data between this mix and its predecessor.
private static InternalInformationPortController	internalInformationPort Reference on component InternalInformationPort.
private boolean	IS_LAST Indicates whether this mix is the lost of the cascade or not.
private static java.util.logging.Logger	LOGGER Logger used to log and display information.
private int	NUMBER_OF_FURTHER_HOPS Number of further mixes between the mix this PreviousMixConnectionHandler belongs to and the receiver.
private OutputStrategyController	outputStrategy Reference on component OutputStrategy (Used to add ChannelReleaseMessages).
private int	PORT Port number this PreviousMixConnectionHandler runs on.
private int	POSITION_OF_MIX_IN_CASCADE The mix' position in the cascade this object belongs to. "1" means "first mix", "2" means "a middle mix" and "3" means "last mix" of cascade.
private java.net.InetAddress	PREVIOUS_MIX_ADDRESS Address of the previous mix in the cascade.
private int	PREVIOUS_MIX_PORT Port number of the previous mix in the cascade.
private java.io.InputStream	previousMixInputStream InputStream for communicating with previous mix.
private java.io.OutputStream	previousMixOutputStream OutputStream for communicating with previous mix.
private java.net.Socket	previousMixSocket Socket for communicating with previous mix.
private java.net.ServerSocket	serverSocket ServerSocket used to accept the previous mix' connection attempt.
private UserDatabaseController	userDatabase Reference on component UserDatabase (Used to add/remove users).

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

protected

PreviousMixConnectionHandler(InputOutputHandlerController inputOutputHandler, UserDatabaseController userDatabase, OutputStrategyController outputStrategy, ExternalInformationPortController externalInformationPort) Constructs a new PreviousMixConnectionHandler which handles communication with a previous mix (in the same cascade as this one).

Method Summary

protected void	acceptConnection() Makes this PreviousMixConnectionHandler wait for its predecessor to connect.
private byte[]	addInterMixHeader(Reply reply) Adds an (encrypted) header to a Reply containing an identifier for the suiting channel (the identifier is unique for any neighboured mixes).
private User	createNewUser(int userIdentifier) Creates a new User with the bypassed identifier.
private byte[]	decryptBlockWithHeader(byte[] blockWithHeader) Decrypts multiplex-header.
private javax.crypto.spec.IvParameterSpec	getInterMixIV(KeyGeneratorController keyGenerator) Generates an initialization vector, that can be used to encrypt multiplex-headers between this mix an its predecessor.
private javax.crypto.SecretKey	getInterMixKey(KeyGeneratorController keyGenerator) Generates a cryptographic key, that can be used to encrypt multiplex-headers between this mix an its predecessor.
private static java.lang.String	getProperty(java.lang.String key) Simply used to shorten method calls (calls internalInformationPort.getProperty(key)).
private void	handleReplies() Waits for Replyies ready to be sent (to the previous mix).
private boolean	isAllowedToSendChannelMessage(User user) Indicates whether the bypassed user is allowed to send a message or not.
private ChannelEstablishMessage	readChannelEstablishMessage(byte[] blockWithHeader, User user) Reads a ChannelEstablishMessage from the previous mix, generates a ChannelEstablishMessage object and returns it.
private ChannelMessage	readChannelMessage(byte[] blockWithHeader, User user) Reads a ChannelMessage from the previous mix, generates a ChannelMessage object and returns it.
private void	resetInterMixCiphers() Resets the Ciphers used to encrypt data between this mix and its predecessor.
void	run() Receives messages from previous mix and passes them to the InputOutputHandler.
private void	setUpInterMixCiphers() Generates a cryptographic key, that is used to encrypt multiplex-headers between this mix an its predecessor and sets up suiting Ciphers.
private void	skipChannelEstablishMessage() Skips a ChannelEstablishMessage on the communication channel.
private void	skipChannelMessage() Skips a ChannelMessage on the communication channel.
private void	waitForConnection() Waits for the previous mix to establish a connection.
private void	waitForIncomingConnection() Waits for the previous mix to connect.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

internalInformationPort

private static InternalInformationPortController internalInformationPort

Reference on component 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.

PORT

private final int PORT

Port number this PreviousMixConnectionHandler runs on.

BIND_ADDRESS

private final java.net.InetAddress BIND_ADDRESS

Address this PreviousMixConnectionHandler's socket shall be bound to.

POSITION_OF_MIX_IN_CASCADE

private final int POSITION_OF_MIX_IN_CASCADE

The mix' position in the cascade this object belongs to. "1" means "first mix", "2" means "a middle mix" and "3" means "last mix" of cascade.

INTER_MIX_BLOCK_SIZE

private final int INTER_MIX_BLOCK_SIZE

Block size of the cryptographic algorithm used to encrypt the multiplex-header.

PREVIOUS_MIX_ADDRESS

private final java.net.InetAddress PREVIOUS_MIX_ADDRESS

Address of the previous mix in the cascade.

PREVIOUS_MIX_PORT

private final int PREVIOUS_MIX_PORT

Port number of the previous mix in the cascade.

NUMBER_OF_FURTHER_HOPS

private final int NUMBER_OF_FURTHER_HOPS

Number of further mixes between the mix this PreviousMixConnectionHandler belongs to and the receiver.

IS_LAST

private final boolean IS_LAST

Indicates whether this mix is the lost of the cascade or not.

previousMixSocket

private java.net.Socket previousMixSocket

Socket for communicating with previous mix.

previousMixInputStream

private java.io.InputStream previousMixInputStream

InputStream for communicating with previous mix.

previousMixOutputStream

private java.io.OutputStream previousMixOutputStream

OutputStream for communicating with previous mix.

interMixEncryptCipherWithPreviousMix

private javax.crypto.Cipher interMixEncryptCipherWithPreviousMix

Cipher for encrypting multiplex-headers of replies.

interMixDecryptCipherWithPreviousMix

private javax.crypto.Cipher interMixDecryptCipherWithPreviousMix

Cipher for decrypting multiplex-headers of requests.

interMixKeyWithPreviousMix

private javax.crypto.SecretKey interMixKeyWithPreviousMix

Key used to encrypt data between this mix and its predecessor.

interMixIVWithPreviousMix

private javax.crypto.spec.IvParameterSpec interMixIVWithPreviousMix

Initialization vector used to encrypt data between this mix and its predecessor.

handleRepliesIsWaitingForConnection

private java.util.concurrent.atomic.AtomicBoolean handleRepliesIsWaitingForConnection

Indicates that method handleReplies() wants to send replies (to the previous mix), but the connection is lost (Used for synchronization, when connection is established again).

See Also:

handleReplies(), waitForIncomingConnection()

serverSocket

private java.net.ServerSocket serverSocket

ServerSocket used to accept the previous mix' connection attempt.

inputOutputHandler

private InputOutputHandlerController inputOutputHandler

Reference on InputOutputHandlerController() (Used to get processed replies and add unprocessed requests).

See Also:

InputOutputHandlerController.addUnprocessedRequest(message.Request), InputOutputHandlerController.getProcessedReply()

userDatabase

private UserDatabaseController userDatabase

Reference on component UserDatabase (Used to add/remove users).

outputStrategy

private OutputStrategyController outputStrategy

Reference on component OutputStrategy (Used to add ChannelReleaseMessages).

externalInformationPort

private ExternalInformationPortController externalInformationPort

Reference on component ExternalInformationPort (Used to provide the cryptographic key used to encrypt/decrypt multiplex-headers to the previous mix.

Constructor Detail

PreviousMixConnectionHandler

protected PreviousMixConnectionHandler(InputOutputHandlerController inputOutputHandler,
                                       UserDatabaseController userDatabase,
                                       OutputStrategyController outputStrategy,
                                       ExternalInformationPortController externalInformationPort)

Constructs a new PreviousMixConnectionHandler which handles communication with a previous mix (in the same cascade as this one). Waits for the previous mix to establish a permanent (TCP) connection, which is used to transmit the messages (Requests and Replyies) of all users connected to the cascade's fist mix (multiplex channel). (De-)multiplexes Requests/Replyies using an (encrypted) header (see addInterMixHeader()).

Requests are put in the InputOutputHandlerController's requestInputQueue (see InputOutputHandlerController.addUnprocessedRequest()). Replyies are taken from the InputOutputHandlerController's replyOutputQueue (see InputOutputHandlerController.getProcessedReply()).

Adds/removes user to/from UserDatabase.

Note: Authentication is NOT implemented!

Parameters:

inputOutputHandler - Reference on InputOutputHandlerController (Used to add messages).

userDatabase - Reference on component UserDatabase (Used to add/remove User)s.

outputStrategy - Reference on component OutputStrategy (Used to add ChannelReleaseMessages).

externalInformationPort - Reference on component ExternalInformationPort (Used to provide the cryptographic key used to encrypt/decrypt multiplex-headers to the previous mix.

Method Detail

acceptConnection

protected void acceptConnection()

Makes this PreviousMixConnectionHandler wait for its predecessor to connect.

handleReplies

private void handleReplies()

Waits for Replyies ready to be sent (to the previous mix).

waitForConnection

private void waitForConnection()

Waits for the previous mix to establish a connection.

addInterMixHeader

private byte[] addInterMixHeader(Reply reply)

Adds an (encrypted) header to a Reply containing an identifier for the suiting channel (the identifier is unique for any neighboured mixes).

Parameters:

reply - Reply without header.

Returns:

Reply with header.

run

public void run()

Receives messages from previous mix and passes them to the InputOutputHandler.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

See Also:

InputOutputHandlerController.addUnprocessedRequest(message.Request)

waitForIncomingConnection

private void waitForIncomingConnection()

Waits for the previous mix to connect. Called when connection to previous mix is lost.

decryptBlockWithHeader

private byte[] decryptBlockWithHeader(byte[] blockWithHeader)

Decrypts multiplex-header.

Parameters:

blockWithHeader - Block of the Request containing the multiplex-header.

Returns:

Decrypted multiplex-header.

createNewUser

private User createNewUser(int userIdentifier)
                    throws java.io.IOException,
                           UserAlreadyExistingException

Creates a new User with the bypassed identifier.

Parameters:

userIdentifier - Used to identify to which user/channel a message belongs.

Returns:

New User.

Throws:

java.io.IOException - If an I/O error occurres.

UserAlreadyExistingException - If a User with the specified identifier is already existing (-> attack or collision).

skipChannelEstablishMessage

private void skipChannelEstablishMessage()
                                  throws java.io.IOException

Skips a ChannelEstablishMessage on the communication channel.

Throws:

java.io.IOException - If an I/O error occurres.

skipChannelMessage

private void skipChannelMessage()
                         throws java.io.IOException

Skips a ChannelMessage on the communication channel.

Throws:

java.io.IOException - If an I/O error occurres.

readChannelEstablishMessage

private ChannelEstablishMessage readChannelEstablishMessage(byte[] blockWithHeader,
                                                            User user)
                                                     throws java.io.IOException

Reads a ChannelEstablishMessage from the previous mix, generates a ChannelEstablishMessage object and returns it.

Parameters:

blockWithHeader - First part of the message (already received since overlapped by the block including the multiplex-header).

user - User the returned message belongs to.

Returns:

The received ChannelEstablishMessage;

Throws:

java.io.IOException - If an I/O error occurres.

readChannelMessage

private ChannelMessage readChannelMessage(byte[] blockWithHeader,
                                          User user)
                                   throws java.io.IOException

Reads a ChannelMessage from the previous mix, generates a ChannelMessage object and returns it.

Parameters:

blockWithHeader - First part of the message (already received since overlapped by the block including the multiplex-header).

user - User the returned message belongs to.

Returns:

The received ChannelMessage;

Throws:

java.io.IOException - If an I/O error occurres.

isAllowedToSendChannelMessage

private boolean isAllowedToSendChannelMessage(User user)

Indicates whether the bypassed user is allowed to send a message or not.

Parameters:

user - Reference on User who's authorization shall be checked.

Returns:

Whether the bypassed user is allowed to send a message or not.

setUpInterMixCiphers

private void setUpInterMixCiphers()

Generates a cryptographic key, that is used to encrypt multiplex-headers between this mix an its predecessor and sets up suiting Ciphers.

resetInterMixCiphers

private void resetInterMixCiphers()

Resets the Ciphers used to encrypt data between this mix and its predecessor. Must be called when connection was lost, since Ciphers might be out of sync in that case.

getInterMixIV

private javax.crypto.spec.IvParameterSpec getInterMixIV(KeyGeneratorController keyGenerator)

Generates an initialization vector, that can be used to encrypt multiplex-headers between this mix an its predecessor.

Parameters:

keyGenerator - Reference on component KeyGenerator (Used to generate the initialization vector).

Returns:

An initialization vector, that can be used to encrypt multiplex-headers between this mix an its predecessor.

getInterMixKey

private javax.crypto.SecretKey getInterMixKey(KeyGeneratorController keyGenerator)

Generates a cryptographic key, that can be used to encrypt multiplex-headers between this mix an its predecessor.

Parameters:

keyGenerator - Reference on component KeyGenerator (Used to generate the cryptographic key).

Returns:

A cryptographic key, that can be used to encrypt multiplex-headers between this mix an its predecessor.

getProperty

private static java.lang.String getProperty(java.lang.String key)

Simply used to shorten method calls (calls internalInformationPort.getProperty(key)). Returns the property with the specified key from the property file.

Parameters:

key - The property key.

Returns:

The property with the specified key in the property file.