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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.proxy.handlers.socks;
21  
22  import java.util.Arrays;
23  
24  import org.apache.mina.core.buffer.IoBuffer;
25  import org.apache.mina.core.filterchain.IoFilter.NextFilter;
26  import org.apache.mina.proxy.session.ProxyIoSession;
27  import org.apache.mina.proxy.utils.ByteUtilities;
28  import org.slf4j.Logger;
29  import org.slf4j.LoggerFactory;
30  
31  /**
32   * Socks4LogicHandler.java - SOCKS4/SOCKS4a authentication mechanisms logic handler.
33   * 
34   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
35   * @since MINA 2.0.0-M3
36   */
37  public class Socks4LogicHandler extends AbstractSocksLogicHandler {
38  
39      private final static Logger logger = LoggerFactory.getLogger(Socks4LogicHandler.class);
40  
41      /**
42       * {@inheritDoc}
43       */
44      public Socks4LogicHandler(final ProxyIoSession proxyIoSession) {
45          super(proxyIoSession);
46      }
47  
48      /**
49       * Perform the handshake.
50       * 
51       * @param nextFilter the next filter
52       */
53      public void doHandshake(final NextFilter nextFilter) {
54          logger.debug(" doHandshake()");
55  
56          // Send request
57          writeRequest(nextFilter, request);
58      }
59  
60      /**
61       * Encode a SOCKS4/SOCKS4a request and writes it to the next filter
62       * so it can be sent to the proxy server.
63       * 
64       * @param nextFilter the next filter
65       * @param request the request to send.
66       */
67      protected void writeRequest(final NextFilter nextFilter, final SocksProxyRequest request) {
68          try {
69              boolean isV4ARequest = Arrays.equals(request.getIpAddress(), SocksProxyConstants.FAKE_IP);
70              byte[] userID = request.getUserName().getBytes("ASCII");
71              byte[] host = isV4ARequest ? request.getHost().getBytes("ASCII") : null;
72  
73              int len = 9 + userID.length;
74  
75              if (isV4ARequest) {
76                  len += host.length + 1;
77              }
78  
79              IoBuffer buf = IoBuffer.allocate(len);
80  
81              buf.put(request.getProtocolVersion());
82              buf.put(request.getCommandCode());
83              buf.put(request.getPort());
84              buf.put(request.getIpAddress());
85              buf.put(userID);
86              buf.put(SocksProxyConstants.TERMINATOR);
87  
88              if (isV4ARequest) {
89                  buf.put(host);
90                  buf.put(SocksProxyConstants.TERMINATOR);
91              }
92  
93              if (isV4ARequest) {
94                  logger.debug("  sending SOCKS4a request");
95              } else {
96                  logger.debug("  sending SOCKS4 request");
97              }
98  
99              buf.flip();
100             writeData(nextFilter, buf);
101         } catch (Exception ex) {
102             closeSession("Unable to send Socks request: ", ex);
103         }
104     }
105 
106     /**
107      * Handle incoming data during the handshake process. Should consume only the
108      * handshake data from the buffer, leaving any extra data in place.
109      * 
110      * @param nextFilter the next filter
111      * @param buf the server response data buffer
112      */
113     public void messageReceived(final NextFilter nextFilter, final IoBuffer buf) {
114         try {
115             if (buf.remaining() >= SocksProxyConstants.SOCKS_4_RESPONSE_SIZE) {
116                 handleResponse(buf);
117             }
118         } catch (Exception ex) {
119             closeSession("Proxy handshake failed: ", ex);
120         }
121     }
122 
123     /**
124      * Handle a SOCKS4/SOCKS4a response from the proxy server. Test
125      * the response buffer reply code and call {@link #setHandshakeComplete()}
126      * if access is granted.
127      * 
128      * @param buf the buffer holding the server response data.
129      * @throws exception if server response is malformed or if request is rejected
130      * by the proxy server.
131      */
132     protected void handleResponse(final IoBuffer buf) throws Exception {
133         byte first = buf.get(0);
134 
135         if (first != 0) {
136             throw new Exception("Socks response seems to be malformed");
137         }
138 
139         byte status = buf.get(1);
140 
141         // Consumes all the response data from the buffer
142         buf.position(buf.position() + SocksProxyConstants.SOCKS_4_RESPONSE_SIZE);
143 
144         if (status == SocksProxyConstants.V4_REPLY_REQUEST_GRANTED) {
145             setHandshakeComplete();
146         } else {
147             throw new Exception("Proxy handshake failed - Code: 0x" + ByteUtilities.asHex(new byte[] { status }) + " ("
148                     + SocksProxyConstants.getReplyCodeAsString(status) + ")");
149         }
150     }
151 }