/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.guacamole.websocket;
import java.io.IOException;
import javax.websocket.CloseReason;
import javax.websocket.CloseReason.CloseCode;
import javax.websocket.Endpoint;
import javax.websocket.EndpointConfig;
import javax.websocket.MessageHandler;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.RemoteEndpoint;
import javax.websocket.Session;
import org.apache.guacamole.GuacamoleException;
import org.apache.guacamole.io.GuacamoleReader;
import org.apache.guacamole.io.GuacamoleWriter;
import org.apache.guacamole.net.GuacamoleTunnel;
import org.apache.guacamole.GuacamoleClientException;
import org.apache.guacamole.GuacamoleConnectionClosedException;
import org.apache.guacamole.protocol.GuacamoleInstruction;
import org.apache.guacamole.protocol.GuacamoleStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A WebSocket implementation of GuacamoleTunnel functionality, compatible with
* the Guacamole.WebSocketTunnel object included with the JavaScript API.
* Messages sent/received are simply chunks of the Guacamole protocol
* instruction stream.
*
* @author Michael Jumper
*/
public abstract class GuacamoleWebSocketTunnelEndpoint extends Endpoint {
/**
* The default, minimum buffer size for instructions.
*/
private static final int BUFFER_SIZE = 8192;
/**
* Logger for this class.
*/
private final Logger logger = LoggerFactory.getLogger(GuacamoleWebSocketTunnelEndpoint.class);
/**
* The underlying GuacamoleTunnel. WebSocket reads/writes will be handled
* as reads/writes to this tunnel.
*/
private GuacamoleTunnel tunnel;
/**
* Sends the given status on the given WebSocket connection and closes the
* connection.
*
* @param session The outbound WebSocket connection to close.
* @param guac_status The status to send.
*/
private void closeConnection(Session session, GuacamoleStatus guac_status) {
try {
CloseCode code = CloseReason.CloseCodes.getCloseCode(guac_status.getWebSocketCode());
String message = Integer.toString(guac_status.getGuacamoleStatusCode());
session.close(new CloseReason(code, message));
}
catch (IOException e) {
logger.debug("Unable to close WebSocket connection.", e);
}
}
/**
* Returns a new tunnel for the given session. How this tunnel is created
* or retrieved is implementation-dependent.
*
* @param session The session associated with the active WebSocket
* connection.
* @param config Configuration information associated with the instance of
* the endpoint created for handling this single connection.
* @return A connected tunnel, or null if no such tunnel exists.
* @throws GuacamoleException If an error occurs while retrieving the
* tunnel, or if access to the tunnel is denied.
*/
protected abstract GuacamoleTunnel createTunnel(Session session, EndpointConfig config)
throws GuacamoleException;
@Override
@OnOpen
public void onOpen(final Session session, EndpointConfig config) {
try {
// Get tunnel
tunnel = createTunnel(session, config);
if (tunnel == null) {
closeConnection(session, GuacamoleStatus.RESOURCE_NOT_FOUND);
return;
}
}
catch (GuacamoleException e) {
logger.error("Creation of WebSocket tunnel to guacd failed: {}", e.getMessage());
logger.debug("Error connecting WebSocket tunnel.", e);
closeConnection(session, e.getStatus());
return;
}
// Manually register message handler
session.addMessageHandler(new MessageHandler.Whole<String>() {
@Override
public void onMessage(String message) {
GuacamoleWebSocketTunnelEndpoint.this.onMessage(message);
}
});
// Prepare read transfer thread
Thread readThread = new Thread() {
/**
* Remote (client) side of this connection
*/
private final RemoteEndpoint.Basic remote = session.getBasicRemote();
@Override
public void run() {
StringBuilder buffer = new StringBuilder(BUFFER_SIZE);
GuacamoleReader reader = tunnel.acquireReader();
char[] readMessage;
try {
// Send tunnel UUID
remote.sendText(new GuacamoleInstruction(
GuacamoleTunnel.INTERNAL_DATA_OPCODE,
tunnel.getUUID().toString()
).toString());
try {
// Attempt to read
while ((readMessage = reader.read()) != null) {
// Buffer message
buffer.append(readMessage);
// Flush if we expect to wait or buffer is getting full
if (!reader.available() || buffer.length() >= BUFFER_SIZE) {
remote.sendText(buffer.toString());
buffer.setLength(0);
}
}
// No more data
closeConnection(session, GuacamoleStatus.SUCCESS);
}
// Catch any thrown guacamole exception and attempt
// to pass within the WebSocket connection, logging
// each error appropriately.
catch (GuacamoleClientException e) {
logger.info("WebSocket connection terminated: {}", e.getMessage());
logger.debug("WebSocket connection terminated due to client error.", e);
closeConnection(session, e.getStatus());
}
catch (GuacamoleConnectionClosedException e) {
logger.debug("Connection to guacd closed.", e);
closeConnection(session, GuacamoleStatus.SUCCESS);
}
catch (GuacamoleException e) {
logger.error("Connection to guacd terminated abnormally: {}", e.getMessage());
logger.debug("Internal error during connection to guacd.", e);
closeConnection(session, e.getStatus());
}
}
catch (IOException e) {
logger.debug("I/O error prevents further reads.", e);
closeConnection(session, GuacamoleStatus.SERVER_ERROR);
}
}
};
readThread.start();
}
@OnMessage
public void onMessage(String message) {
// Ignore inbound messages if there is no associated tunnel
if (tunnel == null)
return;
GuacamoleWriter writer = tunnel.acquireWriter();
try {
// Write received message
writer.write(message.toCharArray());
}
catch (GuacamoleConnectionClosedException e) {
logger.debug("Connection to guacd closed.", e);
}
catch (GuacamoleException e) {
logger.debug("WebSocket tunnel write failed.", e);
}
tunnel.releaseWriter();
}
@Override
@OnClose
public void onClose(Session session, CloseReason closeReason) {
try {
if (tunnel != null)
tunnel.close();
}
catch (GuacamoleException e) {
logger.debug("Unable to close WebSocket tunnel.", e);
}
}
}