/**
* All rights reserved. Licensed 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.jivesoftware.smackx.bytestreams.socks5;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.jivesoftware.smack.SmackConfiguration;
import org.jivesoftware.smack.XMPPException;
/**
* The Socks5Proxy class represents a local SOCKS5 proxy server. It can be enabled/disabled by
* setting the <code>localSocks5ProxyEnabled</code> flag in the <code>smack-config.xml</code> or by
* invoking {@link SmackConfiguration#setLocalSocks5ProxyEnabled(boolean)}. The proxy is enabled by
* default.
* <p>
* The port of the local SOCKS5 proxy can be configured by setting <code>localSocks5ProxyPort</code>
* in the <code>smack-config.xml</code> or by invoking
* {@link SmackConfiguration#setLocalSocks5ProxyPort(int)}. Default port is 7777. If you set the
* port to a negative value Smack tries to the absolute value and all following until it finds an
* open port.
* <p>
* If your application is running on a machine with multiple network interfaces or if you want to
* provide your public address in case you are behind a NAT router, invoke
* {@link #addLocalAddress(String)} or {@link #replaceLocalAddresses(List)} to modify the list of
* local network addresses used for outgoing SOCKS5 Bytestream requests.
* <p>
* The local SOCKS5 proxy server refuses all connections except the ones that are explicitly allowed
* in the process of establishing a SOCKS5 Bytestream (
* {@link Socks5BytestreamManager#establishSession(String)}).
* <p>
* This Implementation has the following limitations:
* <ul>
* <li>only supports the no-authentication authentication method</li>
* <li>only supports the <code>connect</code> command and will not answer correctly to other
* commands</li>
* <li>only supports requests with the domain address type and will not correctly answer to requests
* with other address types</li>
* </ul>
* (see <a href="http://tools.ietf.org/html/rfc1928">RFC 1928</a>)
*
* @author Henning Staib
*/
public class Socks5Proxy {
/* SOCKS5 proxy singleton */
private static Socks5Proxy socks5Server;
/* reusable implementation of a SOCKS5 proxy server process */
private Socks5ServerProcess serverProcess;
/* thread running the SOCKS5 server process */
private Thread serverThread;
/* server socket to accept SOCKS5 connections */
private ServerSocket serverSocket;
/* assigns a connection to a digest */
private final Map<String, Socket> connectionMap = new ConcurrentHashMap<String, Socket>();
/* list of digests connections should be stored */
private final List<String> allowedConnections = Collections.synchronizedList(new LinkedList<String>());
private final Set<String> localAddresses = Collections.synchronizedSet(new LinkedHashSet<String>());
/**
* Private constructor.
*/
private Socks5Proxy() {
this.serverProcess = new Socks5ServerProcess();
// add default local address
try {
this.localAddresses.add(InetAddress.getLocalHost().getHostAddress());
}
catch (UnknownHostException e) {
// do nothing
}
}
/**
* Returns the local SOCKS5 proxy server.
*
* @return the local SOCKS5 proxy server
*/
public static synchronized Socks5Proxy getSocks5Proxy() {
if (socks5Server == null) {
socks5Server = new Socks5Proxy();
}
if (SmackConfiguration.isLocalSocks5ProxyEnabled()) {
socks5Server.start();
}
return socks5Server;
}
/**
* Starts the local SOCKS5 proxy server. If it is already running, this method does nothing.
*/
public synchronized void start() {
if (isRunning()) {
return;
}
try {
if (SmackConfiguration.getLocalSocks5ProxyPort() < 0) {
int port = Math.abs(SmackConfiguration.getLocalSocks5ProxyPort());
for (int i = 0; i < 65535 - port; i++) {
try {
this.serverSocket = new ServerSocket(port + i);
break;
}
catch (IOException e) {
// port is used, try next one
}
}
}
else {
this.serverSocket = new ServerSocket(SmackConfiguration.getLocalSocks5ProxyPort());
}
if (this.serverSocket != null) {
this.serverThread = new Thread(this.serverProcess);
this.serverThread.start();
}
}
catch (IOException e) {
// couldn't setup server
System.err.println("couldn't setup local SOCKS5 proxy on port "
+ SmackConfiguration.getLocalSocks5ProxyPort() + ": " + e.getMessage());
}
}
/**
* Stops the local SOCKS5 proxy server. If it is not running this method does nothing.
*/
public synchronized void stop() {
if (!isRunning()) {
return;
}
try {
this.serverSocket.close();
}
catch (IOException e) {
// do nothing
}
if (this.serverThread != null && this.serverThread.isAlive()) {
try {
this.serverThread.interrupt();
this.serverThread.join();
}
catch (InterruptedException e) {
// do nothing
}
}
this.serverThread = null;
this.serverSocket = null;
}
/**
* Adds the given address to the list of local network addresses.
* <p>
* Use this method if you want to provide multiple addresses in a SOCKS5 Bytestream request.
* This may be necessary if your application is running on a machine with multiple network
* interfaces or if you want to provide your public address in case you are behind a NAT router.
* <p>
* The order of the addresses used is determined by the order you add addresses.
* <p>
* Note that the list of addresses initially contains the address returned by
* <code>InetAddress.getLocalHost().getHostAddress()</code>. You can replace the list of
* addresses by invoking {@link #replaceLocalAddresses(List)}.
*
* @param address the local network address to add
*/
public void addLocalAddress(String address) {
if (address == null) {
throw new IllegalArgumentException("address may not be null");
}
this.localAddresses.add(address);
}
/**
* Removes the given address from the list of local network addresses. This address will then no
* longer be used of outgoing SOCKS5 Bytestream requests.
*
* @param address the local network address to remove
*/
public void removeLocalAddress(String address) {
this.localAddresses.remove(address);
}
/**
* Returns an unmodifiable list of the local network addresses that will be used for streamhost
* candidates of outgoing SOCKS5 Bytestream requests.
*
* @return unmodifiable list of the local network addresses
*/
public List<String> getLocalAddresses() {
return Collections.unmodifiableList(new ArrayList<String>(this.localAddresses));
}
/**
* Replaces the list of local network addresses.
* <p>
* Use this method if you want to provide multiple addresses in a SOCKS5 Bytestream request and
* want to define their order. This may be necessary if your application is running on a machine
* with multiple network interfaces or if you want to provide your public address in case you
* are behind a NAT router.
*
* @param addresses the new list of local network addresses
*/
public void replaceLocalAddresses(List<String> addresses) {
if (addresses == null) {
throw new IllegalArgumentException("list must not be null");
}
this.localAddresses.clear();
this.localAddresses.addAll(addresses);
}
/**
* Returns the port of the local SOCKS5 proxy server. If it is not running -1 will be returned.
*
* @return the port of the local SOCKS5 proxy server or -1 if proxy is not running
*/
public int getPort() {
if (!isRunning()) {
return -1;
}
return this.serverSocket.getLocalPort();
}
/**
* Returns the socket for the given digest. A socket will be returned if the given digest has
* been in the list of allowed transfers (see {@link #addTransfer(String)}) while the peer
* connected to the SOCKS5 proxy.
*
* @param digest identifying the connection
* @return socket or null if there is no socket for the given digest
*/
protected Socket getSocket(String digest) {
return this.connectionMap.get(digest);
}
/**
* Add the given digest to the list of allowed transfers. Only connections for allowed transfers
* are stored and can be retrieved by invoking {@link #getSocket(String)}. All connections to
* the local SOCKS5 proxy that don't contain an allowed digest are discarded.
*
* @param digest to be added to the list of allowed transfers
*/
protected void addTransfer(String digest) {
this.allowedConnections.add(digest);
}
/**
* Removes the given digest from the list of allowed transfers. After invoking this method
* already stored connections with the given digest will be removed.
* <p>
* The digest should be removed after establishing the SOCKS5 Bytestream is finished, an error
* occurred while establishing the connection or if the connection is not allowed anymore.
*
* @param digest to be removed from the list of allowed transfers
*/
protected void removeTransfer(String digest) {
this.allowedConnections.remove(digest);
this.connectionMap.remove(digest);
}
/**
* Returns <code>true</code> if the local SOCKS5 proxy server is running, otherwise
* <code>false</code>.
*
* @return <code>true</code> if the local SOCKS5 proxy server is running, otherwise
* <code>false</code>
*/
public boolean isRunning() {
return this.serverSocket != null;
}
/**
* Implementation of a simplified SOCKS5 proxy server.
*/
private class Socks5ServerProcess implements Runnable {
public void run() {
while (true) {
Socket socket = null;
try {
if (Socks5Proxy.this.serverSocket.isClosed()
|| Thread.currentThread().isInterrupted()) {
return;
}
// accept connection
socket = Socks5Proxy.this.serverSocket.accept();
// initialize connection
establishConnection(socket);
}
catch (SocketException e) {
/*
* do nothing, if caused by closing the server socket, thread will terminate in
* next loop
*/
}
catch (Exception e) {
try {
if (socket != null) {
socket.close();
}
}
catch (IOException e1) {
/* do nothing */
}
}
}
}
/**
* Negotiates a SOCKS5 connection and stores it on success.
*
* @param socket connection to the client
* @throws XMPPException if client requests a connection in an unsupported way
* @throws IOException if a network error occurred
*/
private void establishConnection(Socket socket) throws XMPPException, IOException {
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
DataInputStream in = new DataInputStream(socket.getInputStream());
// first byte is version should be 5
int b = in.read();
if (b != 5) {
throw new XMPPException("Only SOCKS5 supported");
}
// second byte number of authentication methods supported
b = in.read();
// read list of supported authentication methods
byte[] auth = new byte[b];
in.readFully(auth);
byte[] authMethodSelectionResponse = new byte[2];
authMethodSelectionResponse[0] = (byte) 0x05; // protocol version
// only authentication method 0, no authentication, supported
boolean noAuthMethodFound = false;
for (int i = 0; i < auth.length; i++) {
if (auth[i] == (byte) 0x00) {
noAuthMethodFound = true;
break;
}
}
if (!noAuthMethodFound) {
authMethodSelectionResponse[1] = (byte) 0xFF; // no acceptable methods
out.write(authMethodSelectionResponse);
out.flush();
throw new XMPPException("Authentication method not supported");
}
authMethodSelectionResponse[1] = (byte) 0x00; // no-authentication method
out.write(authMethodSelectionResponse);
out.flush();
// receive connection request
byte[] connectionRequest = Socks5Utils.receiveSocks5Message(in);
// extract digest
String responseDigest = new String(connectionRequest, 5, connectionRequest[4]);
// return error if digest is not allowed
if (!Socks5Proxy.this.allowedConnections.contains(responseDigest)) {
connectionRequest[1] = (byte) 0x05; // set return status to 5 (connection refused)
out.write(connectionRequest);
out.flush();
throw new XMPPException("Connection is not allowed");
}
connectionRequest[1] = (byte) 0x00; // set return status to 0 (success)
out.write(connectionRequest);
out.flush();
// store connection
Socks5Proxy.this.connectionMap.put(responseDigest, socket);
}
}
}