| /* |
| * 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.felix.shell.remote; |
| |
| |
| import java.io.IOException; |
| import java.io.PrintStream; |
| import java.net.ServerSocket; |
| import java.net.Socket; |
| import java.net.SocketException; |
| |
| import org.osgi.framework.BundleContext; |
| |
| |
| /** |
| * Implements a simple listener that will accept a single connection. |
| */ |
| class Listener |
| { |
| |
| private int m_Port; |
| private Thread m_ListenerThread; |
| private boolean m_Stop = false; |
| private ServerSocket m_ServerSocket; |
| private AtomicInteger m_UseCounter; |
| private int m_MaxConnections; |
| |
| |
| /** |
| * Activates this listener on a listener thread (telnetconsole.Listener). |
| */ |
| public void activate( BundleContext bundleContext ) |
| { |
| //configure from framework property |
| m_Port = getProperty( bundleContext, "osgi.shell.telnet.port", 6666 ); |
| m_MaxConnections = getProperty( bundleContext, "osgi.shell.telnet.maxconn", 2 ); |
| m_UseCounter = new AtomicInteger( 0 ); |
| m_ListenerThread = new Thread( new Acceptor(), "telnetconsole.Listener" ); |
| m_ListenerThread.start(); |
| }//activate |
| |
| |
| /** |
| * Deactivates this listener. |
| * <p/> |
| * The listener's socket will be closed, which should cause an interrupt in the |
| * listener thread and allow for it to return. The calling thread joins the listener |
| * thread until it returns (to ensure a clean stop). |
| */ |
| public void deactivate() |
| { |
| try |
| { |
| m_Stop = true; |
| //wait for the listener thread |
| m_ServerSocket.close(); |
| m_ListenerThread.join(); |
| } |
| catch ( Exception ex ) |
| { |
| Activator.getServices().error( "Listener::deactivate()", ex ); |
| } |
| }//deactivate |
| |
| /** |
| * Class that implements the listener's accept logic as a <tt>Runnable</tt>. |
| */ |
| private class Acceptor implements Runnable |
| { |
| |
| /** |
| * Listens constantly to a server socket and handles incoming connections. |
| * One connection will be accepted and routed into the shell, all others will |
| * be notified and closed. |
| * <p/> |
| * The mechanism that should allow the thread to unblock from the ServerSocket.accept() call |
| * is currently closing the ServerSocket from another thread. When the stop flag is set, |
| * this should cause the thread to return and stop. |
| */ |
| public void run() |
| { |
| try |
| { |
| /* |
| A server socket is opened with a connectivity queue of a size specified |
| in int floodProtection. Concurrent login handling under normal circumstances |
| should be handled properly, but denial of service attacks via massive parallel |
| program logins should be prevented with this. |
| */ |
| m_ServerSocket = new ServerSocket( m_Port, 1 ); |
| do |
| { |
| try |
| { |
| Socket s = m_ServerSocket.accept(); |
| if ( m_UseCounter.get() >= m_MaxConnections ) |
| { |
| //reject with message |
| PrintStream out = new PrintStream( s.getOutputStream() ); |
| out.print( INUSE_MESSAGE ); |
| out.flush(); |
| //close |
| out.close(); |
| s.close(); |
| } |
| else |
| { |
| m_UseCounter.increment(); |
| //run on the connection thread |
| Thread connectionThread = new Thread( new Shell( s, m_UseCounter ) ); |
| connectionThread.start(); |
| } |
| } |
| catch ( SocketException ex ) |
| { |
| } |
| } |
| while ( !m_Stop ); |
| |
| } |
| catch ( IOException e ) |
| { |
| Activator.getServices().error( "Listener.Acceptor::activate()", e ); |
| } |
| }//run |
| |
| }//inner class Acceptor |
| |
| private static final String INUSE_MESSAGE = "Connection refused.\r\n" |
| + "All possible connections are currently being used.\r\n"; |
| |
| |
| private int getProperty( BundleContext bundleContext, String propName, int defaultValue ) |
| { |
| String propValue = bundleContext.getProperty( propName ); |
| if ( propValue != null ) |
| { |
| try |
| { |
| return Integer.parseInt( propValue ); |
| } |
| catch ( NumberFormatException ex ) |
| { |
| Activator.getServices().error( "Listener::activate()", ex ); |
| } |
| } |
| |
| return defaultValue; |
| } |
| |
| }//class Listener |