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SilverTunnel-NG Netlib is a free library for the Java programming language that implements and encapsulates all the complex network protocol stuff needed for anonymous communication over the Tor anonymity network. Netlib can be easily integrated in almost every existing and new Java application. The library requires Java 1.6/Java SE 6 or a newer version. The original silvertunnel Netlib can be found here : silvertunnel.org
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/*
 * silvertunnel.org Netlib - Java library to easily access anonymity networks
 * Copyright (c) 2009-2012 silvertunnel.org
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see .
 */
/*
 * silvertunnel-ng.org Netlib - Java library to easily access anonymity networks
 * Copyright (c) 2013 silvertunnel-ng.org
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see .
 */

package org.silvertunnel_ng.netlib.adapter.socket;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.net.Socket;
import java.net.SocketImpl;

import org.silvertunnel_ng.netlib.api.NetFactory;
import org.silvertunnel_ng.netlib.api.NetLayer;
import org.silvertunnel_ng.netlib.api.NetLayerIDs;
import org.silvertunnel_ng.netlib.api.util.JavaVersion;
import org.silvertunnel_ng.netlib.layer.mock.NopNetLayer;
import org.silvertunnel_ng.netlib.layer.tcpip.TcpipNetLayer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class allows modification of the JVM global socket handling.
 * 
 * This class contains Java version specific code and does maybe not always
 * work! Detailed description:
 * http://sourceforge.net/apps/trac/silvertunnel/wiki/NetlibAdapterSocket
 * 
 * @author hapke
 * @author Tobias Boese
 */
public class SocketGlobalUtil
{
	/** */
	private static final Logger LOG = LoggerFactory.getLogger(SocketGlobalUtil.class);

	private static NetlibSocketImplFactory netlibSocketImplFactory;

	/**
	 * Initialize the SocketImplFactory of class java.net.Socket.
	 * 
	 * The first lower NetLayer is {@link NopNetLayer} and NOT
	 * {@link TcpipNetLayer} i.e. all requests will fail (and do NOT behave,
	 * from the user perspective, as before calling this method).
	 * 
	 * This method call influences the complete Java JVM.
	 * 
	 * This method can be called multiple times without any problems, but
	 * Socket.setSocketImplFactory() may not be called before the first call of
	 * this method to avoid problems.
	 */
	public static synchronized void initSocketImplFactory()
	{
		if (netlibSocketImplFactory == null)
		{
			try
			{
				final NetLayer defaultNetLayer = NetFactory.getInstance()
						.getNetLayerById(NetLayerIDs.NOP);
				netlibSocketImplFactory = new NetlibSocketImplFactory(
						defaultNetLayer);
				Socket.setSocketImplFactory(netlibSocketImplFactory);
			}
			catch (final IOException e)
			{
				LOG.warn("Socket.setSocketImplFactory() was already called before,"
						+ " but not from SocketUtil, i.e. maybe the wrong factory is set");
			}
		}
	}

	/**
	 * Set a new NetLayer that will be used as/by the SocketImpl inside
	 * java.net.Socket.
	 * 
	 * This method call influences the complete Java JVM.
	 * 
	 * @param netLayer
	 *            the new NetLayer
	 * @throws IllegalStateException
	 *             if initSocketImplFactory() was not called before calling this
	 *             method
	 */
	public static synchronized void setNetLayerUsedBySocketImplFactory(final NetLayer netLayer) throws IllegalStateException
	{
		if (netlibSocketImplFactory == null)
		{
			throw new IllegalStateException(
					"initSocketImplFactory() must be called first (but was not)");
		}

		// action
		netlibSocketImplFactory.setNetLayer(netLayer);
	}

	/**
	 * Create a new Socket with the JDK built-in SocketImpl.
	 * 
	 * The result does not use/depend on a SocketImplFactory set in class
	 * Socket.
	 * 
	 * @return a new (Extended)Socket, as it would be created with new Socket()
	 *         with unset SocketImplFactory
	 * @throws RuntimeException
	 *             if the socket could not be created
	 */
	@SuppressWarnings("unchecked")
	public static ExtendedSocket createOriginalSocket() throws RuntimeException
	{
		if (LOG.isDebugEnabled())
		{
			LOG.debug("createOriginalSocket() called here:",
					new Throwable("stacktrace for debugging - not an error"));
		}

		if (netlibSocketImplFactory == null)
		{
			// SocketImplFactory not yet set (by this class) in class Socket:
			// use default code
			return new ExtendedSocket();
		}
		else
		{
			// SocketImplFactory set in class Socket:
			// use specific special and maybe unportable code

			// 1st attempt,
			// this solution works for Java 1.6, but it does break security
			// restrictions:
			try
			{
				@SuppressWarnings("rawtypes")
				final Class clazz = Class.forName("java.net.SocksSocketImpl");
				@SuppressWarnings("rawtypes")
				final Constructor constructor = clazz.getDeclaredConstructor();
				// this maybe does not work because of security restrictions:
				constructor.setAccessible(true);
				final SocketImpl impl = (SocketImpl) constructor.newInstance();
				return new ExtendedSocket(impl);

			}
			catch (final Throwable t1)
			{
				String msg = "createOriginalSocket()#1st attempt: could not create a Socket for Java Version: "
						+ JavaVersion.getJavaVersion();
				LOG.error(msg, t1);

				// 2nd attempt,
				// this solution doen't work for Java 1.6, but it does not break
				// security restrictions:
				try
				{
					return new ExtendedSocket(new PatchedProxy());

				}
				catch (final Throwable t2)
				{
					msg = "createOriginalSocket()#2nd attempt: could not create a Socket for Java Version: "
							+ JavaVersion.getJavaVersion();
					LOG.error(msg + ", " + t2, t2);

					throw new RuntimeException(msg + ", " + t2);
				}
			}
		}
	}

}