org.spearce.jgit/src/org/spearce/jgit/transport/SshSessionFactory.java

   1 /*
   2  * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
   3  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or
   8  * without modification, are permitted provided that the following
   9  * conditions are met:
  10  *
  11  * - Redistributions of source code must retain the above copyright
  12  *   notice, this list of conditions and the following disclaimer.
  13  *
  14  * - Redistributions in binary form must reproduce the above
  15  *   copyright notice, this list of conditions and the following
  16  *   disclaimer in the documentation and/or other materials provided
  17  *   with the distribution.
  18  *
  19  * - Neither the name of the Git Development Community nor the
  20  *   names of its contributors may be used to endorse or promote
  21  *   products derived from this software without specific prior
  22  *   written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  25  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  26  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  29  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  32  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  33  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  34  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  36  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 package org.spearce.jgit.transport;
  40
  41 import com.jcraft.jsch.JSchException;
  42 import com.jcraft.jsch.Session;
  43
  44 /**
  45  * Creates and destroys SSH connections to a remote system.
  46  * <p>
  47  * Different implementations of the session factory may be used to control
  48  * communicating with the end-user as well as reading their personal SSH
  49  * configuration settings, such as known hosts and private keys.
  50  * <p>
  51  * A {@link Session} must be returned to the factory that created it. Callers
  52  * are encouraged to retain the SshSessionFactory for the duration of the period
  53  * they are using the Session.
  54  */
  55 public abstract class SshSessionFactory {
  56         private static SshSessionFactory INSTANCE = new DefaultSshSessionFactory();
  57
  58         /**
  59          * Get the currently configured JVM-wide factory.
  60          * <p>
  61          * A factory is always available. By default the factory will read from the
  62          * user's <code>$HOME/.ssh</code> and assume OpenSSH compatibility.
  63          *
  64          * @return factory the current factory for this JVM.
  65          */
  66         public static SshSessionFactory getInstance() {
  67                 return INSTANCE;
  68         }
  69
  70         /**
  71          * Change the JVM-wide factory to a different implementation.
  72          *
  73          * @param newFactory
  74          *            factory for future sessions to be created through. If null the
  75          *            default factory will be restored.s
  76          */
  77         public static void setInstance(final SshSessionFactory newFactory) {
  78                 if (newFactory != null)
  79                         INSTANCE = newFactory;
  80                 else
  81                         INSTANCE = new DefaultSshSessionFactory();
  82         }
  83
  84         /**
  85          * Open (or reuse) a session to a host.
  86          * <p>
  87          * A reasonable UserInfo that can interact with the end-user (if necessary)
  88          * is installed on the returned session by this method.
  89          * <p>
  90          * The caller must connect the session by invoking <code>connect()</code>
  91          * if it has not already been connected.
  92          *
  93          * @param user
  94          *            username to authenticate as. If null a reasonable default must
  95          *            be selected by the implementation. This may be
  96          *            <code>System.getProperty("user.name")</code>.
  97          * @param pass
  98          *            optional user account password or passphrase. If not null a
  99          *            UserInfo that supplies this value to the SSH library will be
 100          *            configured.
 101          * @param host
 102          *            hostname (or IP address) to connect to. Must not be null.
 103          * @param port
 104          *            port number the server is listening for connections on. May be <=
 105          *            0 to indicate the IANA registered port of 22 should be used.
 106          * @return a session that can contact the remote host.
 107          * @throws JSchException
 108          *             the session could not be created.
 109          */
 110         public abstract Session getSession(String user, String pass, String host,
 111                         int port) throws JSchException;
 112
 113         /**
 114          * Close (or recycle) a session to a host.
 115          *
 116          * @param session
 117          *            a session previously obtained from this factory's
 118          *            {@link #getSession(String,String, String, int)} method.s
 119          */
 120         public void releaseSession(final Session session) {
 121                 if (session.isConnected())
 122                         session.disconnect();
 123         }
 124 }