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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
40              .getLogger(Socks4LogicHandler.class);
41  
42      /**
43       * {@inheritDoc}
44       */
45      public Socks4LogicHandler(final ProxyIoSession proxyIoSession) {
46          super(proxyIoSession);
47      }
48  
49      /**
50       * Perform the handshake.
51       * 
52       * @param nextFilter the next filter
53       */
54      public void doHandshake(final NextFilter nextFilter) {
55          logger.debug(" doHandshake()");
56  
57          // Send request
58          writeRequest(nextFilter, request);
59      }
60  
61      /**
62       * Encode a SOCKS4/SOCKS4a request and writes it to the next filter
63       * so it can be sent to the proxy server.
64       * 
65       * @param nextFilter the next filter
66       * @param request the request to send.
67       */
68      protected void writeRequest(final NextFilter nextFilter,
69              final SocksProxyRequest request) {
70          try {
71              boolean isV4ARequest = Arrays.equals(request.getIpAddress(),
72                      SocksProxyConstants.FAKE_IP); 
73              byte[] userID = request.getUserName().getBytes("ASCII");
74              byte[] host = isV4ARequest ? request.getHost().getBytes("ASCII")
75                      : null;
76  
77              int len = 9 + userID.length;
78  
79              if (isV4ARequest) {
80                  len += host.length + 1;
81              }
82  
83              IoBuffer buf = IoBuffer.allocate(len);
84  
85              buf.put(request.getProtocolVersion());
86              buf.put(request.getCommandCode());
87              buf.put(request.getPort());
88              buf.put(request.getIpAddress());
89              buf.put(userID);
90              buf.put(SocksProxyConstants.TERMINATOR);
91  
92              if (isV4ARequest) {
93                  buf.put(host);
94                  buf.put(SocksProxyConstants.TERMINATOR);
95              }
96  
97              if (isV4ARequest) {
98                  logger.debug("  sending SOCKS4a request");
99              } else {
100                 logger.debug("  sending SOCKS4 request");
101             }
102 
103             buf.flip();
104             writeData(nextFilter, buf);
105         } catch (Exception ex) {
106             closeSession("Unable to send Socks request: ", ex);
107         }
108     }
109 
110     /**
111      * Handle incoming data during the handshake process. Should consume only the
112      * handshake data from the buffer, leaving any extra data in place.
113      * 
114      * @param nextFilter the next filter
115      * @param buf the server response data buffer
116      */
117     public void messageReceived(final NextFilter nextFilter,
118             final IoBuffer buf) {
119         try {
120             if (buf.remaining() >= SocksProxyConstants.SOCKS_4_RESPONSE_SIZE) {
121                 handleResponse(buf);
122             }
123         } catch (Exception ex) {
124             closeSession("Proxy handshake failed: ", ex);
125         }
126     }
127 
128     /**
129      * Handle a SOCKS4/SOCKS4a response from the proxy server. Test
130      * the response buffer reply code and call {@link #setHandshakeComplete()}
131      * if access is granted.
132      * 
133      * @param buf the buffer holding the server response data.
134      * @throws exception if server response is malformed or if request is rejected
135      * by the proxy server.
136      */
137     protected void handleResponse(final IoBuffer buf) throws Exception {
138         byte first = buf.get(0);
139 
140         if (first != 0) {
141             throw new Exception("Socks response seems to be malformed");
142         }
143 
144         byte status = buf.get(1);
145 
146         // Consumes all the response data from the buffer
147         buf.position(buf.position() + SocksProxyConstants.SOCKS_4_RESPONSE_SIZE);
148         
149         if (status == SocksProxyConstants.V4_REPLY_REQUEST_GRANTED) {
150             setHandshakeComplete();
151         } else {
152             throw new Exception("Proxy handshake failed - Code: 0x"
153                     + ByteUtilities.asHex(new byte[] { status }) + " ("
154                     + SocksProxyConstants.getReplyCodeAsString(status) + ")");
155         }
156     }
157 }