TransformManager.java

/*
 * SIP Communicator, the OpenSource Java VoIP and Instant Messaging client.
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */
package net.java.sip.communicator.impl.media.transform;

import javax.media.rtp.*;

import net.java.sip.communicator.impl.media.transform.dummy.*;
import net.java.sip.communicator.impl.media.transform.srtp.*;
import net.java.sip.communicator.impl.media.transform.zrtp.*;
import net.java.sip.communicator.service.media.*;
import net.java.sip.communicator.util.*;

/**
 * TransformManager class encapsulate the logic of creating different kinds of
 * TransformConnectors. All TransformConnector objects should be created through
 * TransformManager class.
 * 
 * @author Bing SU (nova.su@gmail.com)
 * @author Emanuel Onica (eonica@info.uaic.ro)
 */
public class TransformManager
{
    private static final Logger logger
        = Logger.getLogger(TransformManager.class);

    /**
     * Create a SRTP TransformConnector, which will provide SRTP encryption /
     * decryption functionality, using algorithms defined in RFC3711.
     * 
     * @param addr local RTP session listen address
     * @param masterKey master key of this SRTP session
     * @param masterSalt master salt of this SRTP session
     * @param srtpPolicy SRTP policy for this SRTP session
     * @param srtcpPolicy SRTCP policy for this SRTP session
     * @param cryptoProvider the cryptography services provider selection string
     *        should be obtained from a resource file or by querying 
     * @return the TransformConnector used for SRTP encyption/decryption
     * @throws InvalidSessionAddressException if the local RTP session address
     * is invalid
     */ 
    public static TransformConnector createSRTPConnector(SessionAddress addr,
                                                         byte[] masterKey,
                                                         byte[] masterSalt,
                                                         SRTPPolicy srtpPolicy,
                                                         SRTPPolicy srtcpPolicy)
        throws InvalidSessionAddressException
    {
        SRTPTransformEngine engine = null;

        engine = new SRTPTransformEngine(masterKey, masterSalt, srtpPolicy,
                srtcpPolicy);

        TransformConnector connector = null;

        connector = new TransformConnector(addr, engine);

        return connector;
    }

    /**
     * Creates a connector specific for use in case of ZRTP key management
     * 
     * @param addr local RTP session listen address
     * @param cryptoProvider the cryptography services provider selection string
 *                       should be obtained from a resource file or by querying 
     * @return the TransformConnector used for SRTP encyption/decryption
     * @throws InvalidSessionAddressException
     */
    public static TransformConnector createZRTPConnector(SessionAddress addr,
                                                         CallSession callSession)
        throws InvalidSessionAddressException
    {
        //for adding multistream support the engine should be instantiated 
        //once as a static variable of this class and passed to every ZRTP
        //connector as a parameter
        ZRTPTransformEngine engine = new ZRTPTransformEngine(); 

        TransformConnector connector = new ZrtpTransformConnector(addr, engine);

        //for adding multistream support this method should be replaced with 
        //an addConnector, which should add the connector to an internal engine 
        //connector array; supporting multistream mode by the engine implies
        //the proper management of this connector array - practically every 
        //stream has it's own connector
        engine.setConnector(connector);

        return connector;
    }

    /**
     * Create a dummy TransformConnector. A dummy TransformConnector does no
     * modification (transformation) to RTP/RTCP packets. Its main purpose is to
     * test the TransformationConnector interface and provides a example code
     * of how to use the TransformConnector interfaces.
     * 
     * @param addr local RTP session address
     * @return A dummy TransformationConnector object
     * @throws InvalidSessionAddressException if the local RTP session address
     * is invalid
     */
    public static TransformConnector createDummyConnector(SessionAddress addr)
        throws InvalidSessionAddressException
    {
        DummyTransformEngine engine = new DummyTransformEngine();
        TransformConnector connector = new TransformConnector(addr, engine);

        return connector;
    }
}