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 java.io.OutputStream;
  42
  43 import com.jcraft.jsch.JSchException;
  44 import com.jcraft.jsch.Session;
  45
  46 /**
  47  * Creates and destroys SSH connections to a remote system.
  48  * <p>
  49  * Different implementations of the session factory may be used to control
  50  * communicating with the end-user as well as reading their personal SSH
  51  * configuration settings, such as known hosts and private keys.
  52  * <p>
  53  * A {@link Session} must be returned to the factory that created it. Callers
  54  * are encouraged to retain the SshSessionFactory for the duration of the period
  55  * they are using the Session.
  56  */
  57 public abstract class SshSessionFactory {
  58         private static SshSessionFactory INSTANCE = new DefaultSshSessionFactory();
  59
  60         /**
  61          * Get the currently configured JVM-wide factory.
  62          * <p>
  63          * A factory is always available. By default the factory will read from the
  64          * user's <code>$HOME/.ssh</code> and assume OpenSSH compatibility.
  65          *
  66          * @return factory the current factory for this JVM.
  67          */
  68         public static SshSessionFactory getInstance() {
  69                 return INSTANCE;
  70         }
  71
  72         /**
  73          * Change the JVM-wide factory to a different implementation.
  74          *
  75          * @param newFactory
  76          *            factory for future sessions to be created through. If null the
  77          *            default factory will be restored.s
  78          */
  79         public static void setInstance(final SshSessionFactory newFactory) {
  80                 if (newFactory != null)
  81                         INSTANCE = newFactory;
  82                 else
  83                         INSTANCE = new DefaultSshSessionFactory();
  84         }
  85
  86         /**
  87          * Open (or reuse) a session to a host.
  88          * <p>
  89          * A reasonable UserInfo that can interact with the end-user (if necessary)
  90          * is installed on the returned session by this method.
  91          * <p>
  92          * The caller must connect the session by invoking <code>connect()</code>
  93          * if it has not already been connected.
  94          *
  95          * @param user
  96          *            username to authenticate as. If null a reasonable default must
  97          *            be selected by the implementation. This may be
  98          *            <code>System.getProperty("user.name")</code>.
  99          * @param pass
 100          *            optional user account password or passphrase. If not null a
 101          *            UserInfo that supplies this value to the SSH library will be
 102          *            configured.
 103          * @param host
 104          *            hostname (or IP address) to connect to. Must not be null.
 105          * @param port
 106          *            port number the server is listening for connections on. May be <=
 107          *            0 to indicate the IANA registered port of 22 should be used.
 108          * @return a session that can contact the remote host.
 109          * @throws JSchException
 110          *             the session could not be created.
 111          */
 112         public abstract Session getSession(String user, String pass, String host,
 113                         int port) throws JSchException;
 114
 115         /**
 116          * Close (or recycle) a session to a host.
 117          *
 118          * @param session
 119          *            a session previously obtained from this factory's
 120          *            {@link #getSession(String,String, String, int)} method.s
 121          */
 122         public void releaseSession(final Session session) {
 123                 if (session.isConnected())
 124                         session.disconnect();
 125         }
 126
 127         /**
 128          * Find or create an OutputStream for Ssh to use. For a command line client
 129          * this is probably System.err.
 130          *
 131          * @return an OutputStream to receive the SSH error stream.
 132          */
 133         public abstract OutputStream getErrorStream();
 134 }