001/*
002 *
003 * Copyright the original author or authors
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smackx.bytestreams.socks5;
018
019import java.io.DataInputStream;
020import java.io.DataOutputStream;
021import java.io.IOException;
022import java.net.InetSocketAddress;
023import java.net.Socket;
024import java.net.SocketAddress;
025import java.nio.charset.StandardCharsets;
026import java.util.Arrays;
027import java.util.concurrent.Callable;
028import java.util.concurrent.ExecutionException;
029import java.util.concurrent.FutureTask;
030import java.util.concurrent.TimeUnit;
031import java.util.concurrent.TimeoutException;
032import java.util.logging.Logger;
033
034import org.jivesoftware.smack.SmackException.NoResponseException;
035import org.jivesoftware.smack.SmackException.NotConnectedException;
036import org.jivesoftware.smack.SmackException.SmackMessageException;
037import org.jivesoftware.smack.XMPPException;
038import org.jivesoftware.smack.util.Async;
039import org.jivesoftware.smack.util.CloseableUtil;
040
041import org.jivesoftware.smackx.bytestreams.socks5.packet.Bytestream.StreamHost;
042
043/**
044 * The SOCKS5 client class handles establishing a connection to a SOCKS5 proxy. Connecting to a
045 * SOCKS5 proxy requires authentication. This implementation only supports the no-authentication
046 * authentication method.
047 *
048 * @author Henning Staib
049 */
050public class Socks5Client {
051
052    private static final Logger LOGGER = Logger.getLogger(Socks5Client.class.getName());
053
054    /* stream host containing network settings and name of the SOCKS5 proxy */
055    protected StreamHost streamHost;
056
057    /* SHA-1 digest identifying the SOCKS5 stream */
058    protected String digest;
059
060    /**
061     * Constructor for a SOCKS5 client.
062     *
063     * @param streamHost containing network settings of the SOCKS5 proxy
064     * @param digest identifying the SOCKS5 Bytestream
065     */
066    public Socks5Client(StreamHost streamHost, String digest) {
067        this.streamHost = streamHost;
068        this.digest = digest;
069    }
070
071    /**
072     * Returns the initialized socket that can be used to transfer data between peers via the SOCKS5
073     * proxy.
074     *
075     * @param timeout timeout to connect to SOCKS5 proxy in milliseconds
076     * @return socket the initialized socket
077     * @throws IOException if initializing the socket failed due to a network error
078     * @throws TimeoutException if connecting to SOCKS5 proxy timed out
079     * @throws InterruptedException if the current thread was interrupted while waiting
080     * @throws XMPPException if an XMPP protocol error was received.
081     * @throws SmackMessageException if there was an error.
082     * @throws NotConnectedException if the XMPP connection is not connected.
083     * @throws NoResponseException if there was no response from the remote entity.
084     */
085    public Socket getSocket(int timeout) throws IOException, InterruptedException,
086                    TimeoutException, XMPPException, SmackMessageException, NotConnectedException, NoResponseException {
087        // wrap connecting in future for timeout
088        FutureTask<Socket> futureTask = new FutureTask<>(new Callable<Socket>() {
089
090            @Override
091            public Socket call() throws IOException, SmackMessageException {
092
093                // initialize socket
094                Socket socket = new Socket();
095                SocketAddress socketAddress = new InetSocketAddress(streamHost.getAddress().asInetAddress(),
096                                streamHost.getPort());
097                socket.connect(socketAddress);
098
099                // initialize connection to SOCKS5 proxy
100                try {
101                    establish(socket);
102                }
103                catch (IOException e) {
104                    if (!socket.isClosed()) {
105                        CloseableUtil.maybeClose(socket, LOGGER);
106                    }
107                    throw e;
108                }
109
110                return socket;
111            }
112
113        });
114        Async.go(futureTask, "SOCKS5 client connecting to " + streamHost);
115
116        // get connection to initiator with timeout
117        try {
118            return futureTask.get(timeout, TimeUnit.MILLISECONDS);
119        }
120        catch (ExecutionException e) {
121            var causingException = e.getCause();
122            if (causingException instanceof IOException)
123                throw (IOException) causingException;
124            throw new IOException("ExecutionException while SOCKS5 client attempting to connect to " + streamHost, e);
125        }
126
127    }
128
129    /**
130     * Initializes the connection to the SOCKS5 proxy by negotiating authentication method and
131     * requesting a stream for the given digest. Currently only the no-authentication method is
132     * supported by the Socks5Client.
133     *
134     * @param socket connected to a SOCKS5 proxy
135     * @throws IOException if an I/O error occurred.
136     */
137    protected void establish(Socket socket) throws IOException {
138
139        byte[] connectionRequest;
140        byte[] connectionResponse;
141        /*
142         * use DataInputStream/DataOutputStream to assure read and write is completed in a single
143         * statement
144         */
145        DataInputStream in = new DataInputStream(socket.getInputStream());
146        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
147
148        // authentication negotiation
149        byte[] cmd = new byte[3];
150
151        cmd[0] = (byte) 0x05; // protocol version 5
152        cmd[1] = (byte) 0x01; // number of authentication methods supported
153        cmd[2] = (byte) 0x00; // authentication method: no-authentication required
154
155        out.write(cmd);
156        out.flush();
157
158        byte[] response = new byte[2];
159        in.readFully(response);
160
161        // check if server responded with correct version and no-authentication method
162        if (response[0] != (byte) 0x05 || response[1] != (byte) 0x00) {
163            throw new IOException("Remote SOCKS5 server responded with unexpected version: " + response[0] + ' ' + response[1] + ". Should be 0x05 0x00.");
164        }
165
166        // request SOCKS5 connection with given address/digest
167        connectionRequest = createSocks5ConnectRequest();
168        out.write(connectionRequest);
169        out.flush();
170
171        // receive response
172        connectionResponse = Socks5Utils.receiveSocks5Message(in);
173
174        // verify response
175        connectionRequest[1] = (byte) 0x00; // set expected return status to 0
176        if (!Arrays.equals(connectionRequest, connectionResponse)) {
177            throw new IOException(
178                            "Connection request does not equal connection response. Response: "
179                                            + Arrays.toString(connectionResponse) + ". Request: "
180                                            + Arrays.toString(connectionRequest));
181        }
182    }
183
184    /**
185     * Returns a SOCKS5 connection request message. It contains the command "connect", the address
186     * type "domain" and the digest as address.
187     * <p>
188     * (see <a href="http://tools.ietf.org/html/rfc1928">RFC1928</a>)
189     *
190     * @return SOCKS5 connection request message
191     */
192    private byte[] createSocks5ConnectRequest() {
193        byte[] addr = digest.getBytes(StandardCharsets.UTF_8);
194
195        byte[] data = new byte[7 + addr.length];
196        data[0] = (byte) 0x05; // version (SOCKS5)
197        data[1] = (byte) 0x01; // command (1 - connect)
198        data[2] = (byte) 0x00; // reserved byte (always 0)
199        data[3] = (byte) 0x03; // address type (3 - domain name)
200        data[4] = (byte) addr.length; // address length
201        System.arraycopy(addr, 0, data, 5, addr.length); // address
202        data[data.length - 2] = (byte) 0; // address port (2 bytes always 0)
203        data[data.length - 1] = (byte) 0;
204
205        return data;
206    }
207
208}