anon.client

Class AnonTCPChannel

java.lang.Object

anon.client.AnonTCPChannel

All Implemented Interfaces:

AnonChannel

public class AnonTCPChannel
extends java.lang.Object
implements AnonChannel

This class can be used to create an anonymous TCP channel to a given host:port. You first create an unconnected channel of type TCP using AnonService.createChannel(AnonChannel.TCP). Afterwards you connect to the target host using connect. Data transmission can be done by using the Input-/Outputstream returned by getInputStream() / getOutputStream().

Hint: for performance optimisation / efficiency have a look at setSentAutoFlushDelay(int).

Example:

  AnonService anonservice=AnonServiceFactory.getAnonServiceInstance(AnonServiceFactory.SERVICE_ANON);
  AnonTCPChannel anonchannel=(AnonTCPChannel)anonservice.createChannel(AnonChannel.TCP);
  anonchannel.connect("desti.nation",80);
  InputStream in=anonchannel.getInputStream();
  OutputStream out=anonchannel.getOutputStream();
  in.read();
  out.write(...);
  anonchannel.close();

Note: Since the AnonTCPChannel implementation uses an anonymous SOCKS channel, an AnonTCPChannel can only be established using a cascade which supports SOCKS.

Author:

sk13

Field Summary

Fields inherited from interface anon.AnonChannel

HTTP, SMTP, SOCKS, TCP, UDP, UDP_OVER_TCP, UDP_OVER_UDP, VPN

Method Summary

Modifier and Type	Method and Description
void	close() Closes the channel and releases all resources used.
void	connect(java.lang.String hostname, int port) Establishes an anonymous TCP connection to the given host:port.
java.io.InputStream	getInputStream() The returned InputStream could be used to receive data.
int	getOutputBlockSize() Returns a value that indicates the current optimum size of data to write.
java.io.OutputStream	getOutputStream() The returned OutputStream could be used to send data.
boolean	isClosed() Returns if the channel is already closed, i.e. no data can be sent / recieved any more on this channel.
void	setSentAutoFlushDelay(int msAutoFlushDelay) Sets the time to wait before actually sending some data over this channel in case the packet belonging to the underlying anonymisation protocol is not full yet.

Methods inherited from class java.lang.Object

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

Method Detail

connect

public void connect(java.lang.String hostname,
                    int port)
             throws java.io.IOException

Establishes an anonymous TCP connection to the given host:port.

Parameters:

hostname - the domain name of the target host

port - the target port number

Throws:

java.io.IOException - if the connection could not be established

setSentAutoFlushDelay

public void setSentAutoFlushDelay(int msAutoFlushDelay)

Sets the time to wait before actually sending some data over this channel in case the packet belonging to the underlying anonymisation protocol is not full yet.

This method can be used for performance optimisations / efficiency. One use case would be if you know that this channel will sent data immediately after connection establishment. Therefore you would call setSentAutoFlushDelay with some delayvalue > 0 just before you call the connect method. If you call Outputstream.write within delayvalue milliseconds after the connect call then the data you intend to sent will be piggybacked on the connect request. This will save some roundtrip-time delay.

Additionally, using this method correctly could decrease the bandwidth overhead introduced by the underlying anonymisation protocol. Many anonymisation protocols fragment the data stream into fixed sized packets which are filled with dummy data if not enough real data is available. Therefore waiting a certain amount of time for additional real data can increase the channel utilisation.

Note: This method will not do anything at the moment as the implementation is not ready yet.

Parameters:

msAutoFlushDelay - the amount of time in milliseconds to wait for new data before the current sent buffer is flushed. Setting this value to 0 will always auto flush immediately. Setting this value to -1 will only flush the sent buffer, if the sent buffer is full, i.e. getOutputBufgferSize many bytes are contained in the buffer.

getInputStream

public java.io.InputStream getInputStream()

Description copied from interface: AnonChannel

The returned InputStream could be used to receive data.

Specified by:

getInputStream in interface AnonChannel

Returns:

InputStream, useful for receiving data

getOutputStream

public java.io.OutputStream getOutputStream()

Description copied from interface: AnonChannel

The returned OutputStream could be used to send data.

Specified by:

getOutputStream in interface AnonChannel

Returns:

OutputStream, useful for sending data

getOutputBlockSize

public int getOutputBlockSize()

Description copied from interface: AnonChannel

Returns a value that indicates the current optimum size of data to write. Because often anon services transport the data fragmented into fixed sized packets for optimum performance it may be good to send data according to the packet size to avoid unneccessary overheads.

Specified by:

getOutputBlockSize in interface AnonChannel

Returns:

the current optimum size for output data. If 1 is returned the size does not matter.

close

public void close()

Description copied from interface: AnonChannel

Closes the channel and releases all resources used.

Specified by:

close in interface AnonChannel

isClosed

public boolean isClosed()

Description copied from interface: AnonChannel

Returns if the channel is already closed, i.e. no data can be sent / recieved any more on this channel.

Specified by:

isClosed in interface AnonChannel

Returns:

true, if the channel is already closed