mail.communication.inet
Class InetCommunicator

java.lang.Object
  mail.communication.Communicator
      mail.communication.inet.InetCommunicator

All Implemented Interfaces:

java.lang.Runnable

public class InetCommunicator
extends Communicator
implements java.lang.Runnable

Author:

Arne Müller

Field Summary

private java.util.Collection<InetAddress>	addr this communicators address
private java.io.File	basedir directory in which comm-properties are stored
static int	BOOT_TIMEOUT
private java.util.Properties	bootstrap
private static java.lang.String	BOOTSTRAP_ADDR
static int	CONNECTION_TIMEOUT the time after which a connection is considered dead.
(package private) java.util.Hashtable<InetAddress,java.lang.Long>	connections map of connections to their last response time
private javax.xml.parsers.DocumentBuilderFactory	docfactory used to build the XML documents needed to send packages
(package private) boolean	ip_answer indicates if this communicators ip address was updated
private LocalNode	local the local node this communicator is attached to
private static int	MAX_BOOTSTRAP_TRIES
static int	PING_INTERVAL the interval PING packages get send to neighbor nodes, to keep the UDP connection alive, because if the UDP connection collapse it might be hard to rebuild it (UDP hole punching)
(package private) java.util.Hashtable<InetAddress,java.util.Vector<UDP>>	received contains received, unfinished packets
(package private) java.util.Hashtable<InetAddress,java.lang.Integer>	responses list of received elementar response packets
private java.util.Properties	settings
private static java.lang.String	SETTINGS
private java.net.DatagramSocket	socket the socket all packets are send and received with.
static int	TIMEOUT If TIMEOUT ms have passed after an request, the package is believed of have gotten lost
private javax.xml.transform.TransformerFactory	transFactory used to transform XML documents into OutputStreams
(package private) java.util.Hashtable<Node,InetAddress>	useableAddresses maps Nodes to InetAddresses of the Node, that work

Constructor Summary

InetCommunicator()
creates a new InetCommunicator.

InetCommunicator(java.io.File basedir)

InetCommunicator(int port)
creates a new InetCommunicator.

Method Summary

void	attachNode(LocalNode l)
void	bootstrap()
void	close()
private boolean	connectionEstablished(InetAddress address) looks up the time, when the last package was received.
private void	establishConnection(InetAddress address) establishes a connection.
void	findMyAddress(Address apeer)
java.util.Collection<Address>	getAddress() returns the Address this Communicator uses to send Packets
javax.xml.parsers.DocumentBuilder	getDocumentBuilder()
boolean	isOpen()
boolean	open()
void	open(int port)
InetAddress	parseAddress(java.lang.String addr)
private void	print_debug(org.w3c.dom.Document d) print a Document to System.out.
private void	punch_hole(InetAddress action) sends PING packets to punch a UDP hole into the NAT router this peer is hidden behind
private void	receivePackage(java.io.InputStream in, InetAddress sender) builds a CPackage out of the InputStream.
private void	request_hole_punch(InetAddress action, InetAddress sender) sends a node a request to punch a UDP hole for another node
private void	reset(InetAddress address, int reply) resets the specified entry at adress in the response list
void	run() this methods listens for Packets send to this peer and handles them appropriately.
void	sendPackage(CPackage p, Address to)
void	sendPackage(CPackage p, RemoteNode to)
private void	startConnectionHolder() starts the mechanism to keep UDP connections alive.
private int	waitForEcho(InetAddress address) waits until any reply came from address.
private int	waitForEcho(InetAddress address, int reply) waits until the specified reply came from address.
void	write(org.w3c.dom.Document d, java.io.File out)

Methods inherited from class mail.communication.Communicator

getReplyList

Methods inherited from class java.lang.Object

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

Field Detail

BOOTSTRAP_ADDR

private static final java.lang.String BOOTSTRAP_ADDR

See Also:

Constant Field Values

SETTINGS

private static final java.lang.String SETTINGS

See Also:

Constant Field Values

MAX_BOOTSTRAP_TRIES

private static final int MAX_BOOTSTRAP_TRIES

See Also:

Constant Field Values

basedir

private java.io.File basedir

directory in which comm-properties are stored

bootstrap

private java.util.Properties bootstrap

settings

private java.util.Properties settings

BOOT_TIMEOUT

public static final int BOOT_TIMEOUT

See Also:

Constant Field Values

TIMEOUT

public static final int TIMEOUT

If TIMEOUT ms have passed after an request, the package is believed of have gotten lost

See Also:

Constant Field Values

PING_INTERVAL

public static final int PING_INTERVAL

the interval PING packages get send to neighbor nodes, to keep the UDP connection alive, because if the UDP connection collapse it might be hard to rebuild it (UDP hole punching)

See Also:

Constant Field Values

CONNECTION_TIMEOUT

public static final int CONNECTION_TIMEOUT

the time after which a connection is considered dead.

See Also:

Constant Field Values

local

private LocalNode local

the local node this communicator is attached to

addr

private java.util.Collection<InetAddress> addr

this communicators address

docfactory

private javax.xml.parsers.DocumentBuilderFactory docfactory

used to build the XML documents needed to send packages

transFactory

private javax.xml.transform.TransformerFactory transFactory

used to transform XML documents into OutputStreams

socket

private java.net.DatagramSocket socket

the socket all packets are send and received with. On a local machine this socket will stay at the same port, but over NAT?

received

java.util.Hashtable<InetAddress,java.util.Vector<UDP>> received

contains received, unfinished packets

responses

java.util.Hashtable<InetAddress,java.lang.Integer> responses

list of received elementar response packets

connections

java.util.Hashtable<InetAddress,java.lang.Long> connections

map of connections to their last response time

useableAddresses

java.util.Hashtable<Node,InetAddress> useableAddresses

maps Nodes to InetAddresses of the Node, that work

ip_answer

boolean ip_answer

indicates if this communicators ip address was updated

Constructor Detail

InetCommunicator

public InetCommunicator()

creates a new InetCommunicator.

InetCommunicator

public InetCommunicator(java.io.File basedir)

InetCommunicator

public InetCommunicator(int port)
                 throws java.io.IOException

creates a new InetCommunicator. The socket will be created. Package receiving and other necessary methods to keep a communication running are established.

Throws:

java.io.IOException

Method Detail

open

public boolean open()
             throws java.io.IOException

Throws:

java.io.IOException

bootstrap

public void bootstrap()
               throws BootstrapException

Throws:

BootstrapException

isOpen

public boolean isOpen()

Specified by:

isOpen in class Communicator

open

public void open(int port)
          throws java.io.IOException

Throws:

java.io.IOException

close

public void close()

Specified by:

close in class Communicator

attachNode

public void attachNode(LocalNode l)

Specified by:

attachNode in class Communicator

getAddress

public java.util.Collection<Address> getAddress()

Description copied from class: Communicator

returns the Address this Communicator uses to send Packets

Specified by:

getAddress in class Communicator

Returns:

findMyAddress

public void findMyAddress(Address apeer)
                   throws java.io.IOException

Specified by:

findMyAddress in class Communicator

Throws:

java.io.IOException

getDocumentBuilder

public javax.xml.parsers.DocumentBuilder getDocumentBuilder()

Specified by:

getDocumentBuilder in class Communicator

parseAddress

public InetAddress parseAddress(java.lang.String addr)
                         throws IncompatibleAddressException

Specified by:

parseAddress in class Communicator

Throws:

IncompatibleAddressException

print_debug

private void print_debug(org.w3c.dom.Document d)

print a Document to System.out. For debugging

Parameters:

d - the document to print

write

public void write(org.w3c.dom.Document d,
                  java.io.File out)
           throws javax.xml.transform.TransformerException,
                  java.io.IOException

Specified by:

write in class Communicator

Throws:

javax.xml.transform.TransformerException

java.io.IOException

startConnectionHolder

private void startConnectionHolder()

starts the mechanism to keep UDP connections alive. This is necessary, because some UDP connections might have been established via UDP hole punching. This means, that neither communication partner is able to reastablish the connection once it is dead, because each others NAT routers are blocking unknown packets from the outside. If packets are send on regular intervals the router will expect packets and thus keep the connection.

connectionEstablished

private boolean connectionEstablished(InetAddress address)

looks up the time, when the last package was received. If that's to long ago, the connection is considered dead

Parameters:

address - the address the connection belongs to

Returns:

true, if the connection is alive

establishConnection

private void establishConnection(InetAddress address)
                          throws UDP.UDPException,
                                 java.io.IOException

establishes a connection. First a simple ping is tried to test, if the other peer might be able to answer directly. If this is not the case, the other peer is probably behind a NAT router, so UDP hole punching is tried. In UDP hole punching the peer gets told of the connection request from a third peer, who already has got a connection, and then answers (even if he didn't get the packet). The NAT Router thinks, he established the connection and thus now allows also the other packets in.

Parameters:

address - the address to connect to

Throws:

java.io.IOException - if no connection could be established

UDP.UDPException

waitForEcho

private int waitForEcho(InetAddress address)

waits until any reply came from address. Only ECHO replies are marked received

Parameters:

address - the address to listen at

Returns:

the reply, or UDP.NO_REPLY, if TIMEOUT ms no message came

waitForEcho

private int waitForEcho(InetAddress address,
                        int reply)

waits until the specified reply came from address. The reply is marked received

Parameters:

address - the Address to listen at

reply - the reply to wait for

Returns:

the reply, or UDP.NO_REPLY, if TIMEOUT ms no reply came

reset

private void reset(InetAddress address,
                   int reply)

resets the specified entry at adress in the response list

Parameters:

address - the address to reset

reply - the reply to reset at the address

punch_hole

private void punch_hole(InetAddress action)

sends PING packets to punch a UDP hole into the NAT router this peer is hidden behind

Parameters:

action - the address to enable the communication to

request_hole_punch

private void request_hole_punch(InetAddress action,
                                InetAddress sender)

sends a node a request to punch a UDP hole for another node

Parameters:

action - the node to send the request to

sender - the node to punch the UDP hole for

run

public void run()

this methods listens for Packets send to this peer and handles them appropriately. If a complete Package is received receivePackage(InputStream, InetAddress) is executed

Specified by:

run in interface java.lang.Runnable

receivePackage

private void receivePackage(java.io.InputStream in,
                            InetAddress sender)

builds a CPackage out of the InputStream. reads the InputStream and builds a XML Document. The XML Document is used to build the Package.

Parameters:

in - the InputStream containing the data

sender - the address of the sender of the package (might not be usable if the sender used tor)

sendPackage

public void sendPackage(CPackage p,
                        RemoteNode to)
                 throws IncompatibleAddressException,
                        NotReachableException,
                        PackageBuildException

Specified by:

sendPackage in class Communicator

Throws:

IncompatibleAddressException

NotReachableException

PackageBuildException

sendPackage

public void sendPackage(CPackage p,
                        Address to)
                 throws IncompatibleAddressException,
                        java.io.IOException,
                        PackageBuildException

Specified by:

sendPackage in class Communicator

Throws:

IncompatibleAddressException

java.io.IOException

PackageBuildException