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1   /*
2    * Copyright 2007-2008 the original author or authors.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.gwe.drivers.netAccess.tunneling;
18  
19  import java.io.IOException;
20  import java.net.ServerSocket;
21  
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  import org.gwe.drivers.HandleCreationException;
25  import org.gwe.drivers.HandleOperationException;
26  import org.gwe.drivers.netAccess.HostHandle;
27  import org.gwe.drivers.netAccess.RemoteHostHandle;
28  import org.gwe.utils.security.ResourceLink;
29  import org.gwe.utils.security.ThinURI;
30  
31  /**
32   * @author Marco Ruiz
33   * @since Dec 7, 2008
34   */
35  public class HostTunnel {
36  	
37  	private static Log log = LogFactory.getLog(HostTunnel.class);
38  
39  	public static final int NO_TUNNEL_PORT = -1;
40  
41  	// Remote to local ports map
42  	private int localPort = NO_TUNNEL_PORT; 
43  	
44  	private ResourceLink<? extends RemoteHostHandle> hostLink;
45  	private RemoteHostHandle hostHandle;
46  	
47  	public <HANDLE_TYPE> HostTunnel(ResourceLink<? extends HostHandle> link) {
48  		if (link != null && !RemoteHostHandle.class.isAssignableFrom(link.getHandleClass())) link = null;
49  	    this.hostLink = (ResourceLink<? extends RemoteHostHandle>) link;
50      }
51  	
52  	public int openTunnel(ThinURI hostURI, int remotePort, boolean force) throws HostTunnelException {
53  		if (hostLink == null) return remotePort;
54  		if (force) disposeHandle();
55  
56  		if (hostHandle == null) resetTunnel(remotePort);  
57  		return getTunnelPort(remotePort);
58  	}
59  
60  	private void disposeHandle() {
61  		if (hostHandle == null) return;
62          try {
63  	        hostHandle.close();
64          } catch (HandleOperationException e) {
65  	        // TODO Auto-generated catch block
66          }
67  	    hostHandle = null;
68      }
69  
70  	private void resetTunnel(int remotePort) throws HostTunnelException {
71  		localPort = NO_TUNNEL_PORT;
72  	    try {
73  	    	hostHandle = hostLink.createHandle();
74  	    } catch (HandleCreationException e) {
75  			throw new HostTunnelException("Problems creating host handle to tunnel port " + remotePort + " for link '" + hostLink + "'", e);
76  	    }
77      }
78  
79  	private int getTunnelPort(int remotePort) throws HostTunnelException {
80  		if (localPort != NO_TUNNEL_PORT) return localPort;
81  	    try {
82  		    localPort = findFreePort();
83  		    hostHandle.openTunnel(localPort, remotePort);
84  		    return localPort;
85  		} catch (IOException e) {
86  			throw new HostTunnelException("Could not find a local free port to establish tunnel for link '" + hostLink + "'", e);
87  	    } catch (HandleOperationException e) {
88  			throw new HostTunnelException("Problems establishing tunnel to port " + remotePort + " for link '" + hostLink + "'", e);
89  	    }
90      }
91  	
92  	private int findFreePort() throws IOException {
93  		ServerSocket server = new ServerSocket(0);
94  		int port = server.getLocalPort();
95  		server.close();
96  		return port;
97  	}
98  }
99  
100