/*
* Copyright (c) 2002-2010 Atsuhiko Yamanaka, JCraft,Inc. All rights reserved.
* Copyright (c) 2010-2011 Michael Laudati, N1 Concepts LLC.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
* INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.vngx.jsch;
import org.vngx.jsch.constants.ConnectionProtocol;
import org.vngx.jsch.exception.JSchException;
/**
* <p>Base implementation of a SSH request which sends a request packet over the
* session to the specific channel and optionally waits for a response.</p>
*
* <p>After the key exchange, the client requests a service. The service is
* identified by a name.
* <pre>
* byte SSH_MSG_SERVICE_REQUEST
* string service name
* </pre></p>
*
* <p>If the server rejects the service request, it SHOULD send an appropriate
* SSH_MSG_DISCONNECT message and MUST disconnect. When the service starts, it
* may have access to the session identifier generated during the key exchange.
* If the server supports the service (and permits the client to use it), it
* MUST respond with the following:
* <pre>
* byte SSH_MSG_SERVICE_ACCEPT
* string service name
* </pre></p>
*
* <p>Message numbers used by services should be in the area reserved for them.
* The transport level will continue to process its own messages.</p>
*
* <p><a href="http://tools.ietf.org/html/rfc4254">RFC 4254 - The Secure Shell
* (SSH) Connection Protocol</a></p>
*
* @author Atsuhiko Yamanaka
* @author Michael Laudati
*/
abstract class Request implements ConnectionProtocol {
/** True if the request waits for a reply from server. */
private boolean _reply = false;
/** Session to send request through. */
private Session _session;
/** Channel to send request for. */
private Channel _channel;
/**
* Uses the specified {@code session} and {@code channel} to make the
* request to server. Implementations should override this method to
* implement request specific logic.
*
* @param session
* @param channel
* @throws Exception
*/
void request(Session session, Channel channel) throws Exception {
_session = session;
_channel = channel;
// TODO Why FORCE set reply to true if channel has a timeout?!?
if( channel._connectTimeout > 0 ) {
setReply(true);
}
}
/**
* Returns {@code true} if the request should wait for a reply from the
* server.
*
* @return true if request waits for reply from server
*/
final boolean waitForReply() {
return _reply;
}
/**
* Sets if the request will wait for a reply from the server.
*
* @param reply
*/
final void setReply(boolean reply) {
_reply = reply;
}
/**
* Writes the specified SSH packet to the session through the channel.
*
* If the request has been set to wait for a reply, then the calling thread
* will wait for a reply from the server. The response from the server is
* received in the underlying session and the channel's reply value is set
* to 1 for a request success or 0 for a request failure. The connection's
* timeout value in milliseconds is used to determine the timeout for
* waiting for a reply (0 or less timeout indicates no timeout).
*
* @param packet to write
* @throws Exception if any errors occur
*/
final void write(final Packet packet) throws Exception {
if( _reply ) { // Reset channel's reply to -1, reply will be
_channel._reply = -1; // set by the session when response is received
} // to 1 for success or 0 for failure
_session.write(packet);
if( _reply ) {
long start = System.currentTimeMillis();
long timeout = _channel._connectTimeout;
while( _channel.isConnected() && _channel._reply == -1 ) { // reply will be changed by session
try {
Thread.sleep(10);
} catch(InterruptedException e) { /* Ignore error. */ }
if( timeout > 0L && (System.currentTimeMillis() - start) > timeout ) {
_channel._reply = 0;
throw new JSchException("Channel request timed out after "+_channel._connectTimeout+"ms, "+getClass().getSimpleName());
}
}
if( _channel._reply == 0 ) { // Should this be an exception?
throw new JSchException("Server responded with failure for channel request, "+getClass().getSimpleName());
}
}
}
}