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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 org.apache.mina.core.buffer.IoBuffer;
23  import org.apache.mina.core.filterchain.IoFilter.NextFilter;
24  import org.apache.mina.proxy.session.ProxyIoSession;
25  import org.apache.mina.proxy.utils.ByteUtilities;
26  import org.slf4j.Logger;
27  import org.slf4j.LoggerFactory;
28  
29  /**
30   * Socks4LogicHandler.java - SOCKS4/SOCKS4a authentication mechanisms logic handler.
31   * 
32   * @author The Apache MINA Project (dev@mina.apache.org)
33   * @since MINA 2.0.0-M3
34   */
35  public class Socks4LogicHandler extends AbstractSocksLogicHandler {
36  
37      private final static Logger logger = LoggerFactory
38              .getLogger(Socks4LogicHandler.class);
39  
40      /**
41       * {@inheritDoc}
42       */
43      public Socks4LogicHandler(final ProxyIoSession proxyIoSession) {
44          super(proxyIoSession);
45      }
46  
47      /**
48       * Perform the handshake.
49       * 
50       * @param nextFilter the next filter
51       */
52      public void doHandshake(final NextFilter nextFilter) {
53          logger.debug(" doHandshake()");
54  
55          // Send request
56          writeRequest(nextFilter, request);
57      }
58  
59      /**
60       * Encode a SOCKS4/SOCKS4a request and writes it to the next filter
61       * so it can be sent to the proxy server.
62       * 
63       * @param nextFilter the next filter
64       * @param request the request to send.
65       */
66      protected void writeRequest(final NextFilter nextFilter,
67              final SocksProxyRequest request) {
68          try {
69              boolean isV4ARequest = request.getHost() != null;
70              byte[] userID = request.getUserName().getBytes("ASCII");
71              byte[] host = isV4ARequest ? request.getHost().getBytes("ASCII")
72                      : null;
73  
74              int len = 9 + userID.length;
75  
76              if (isV4ARequest) {
77                  len += host.length + 1;
78              }
79  
80              IoBuffer buf = IoBuffer.allocate(len);
81  
82              buf.put(request.getProtocolVersion());
83              buf.put(request.getCommandCode());
84              buf.put(request.getPort());
85              buf.put(request.getIpAddress());
86              buf.put(userID);
87              buf.put(SocksProxyConstants.TERMINATOR);
88  
89              if (isV4ARequest) {
90                  buf.put(host);
91                  buf.put(SocksProxyConstants.TERMINATOR);
92              }
93  
94              if (isV4ARequest) {
95                  logger.debug("  sending SOCKS4a request");
96              } else {
97                  logger.debug("  sending SOCKS4 request");
98              }
99  
100             buf.flip();
101             writeData(nextFilter, buf);
102         } catch (Exception ex) {
103             closeSession("Unable to send Socks request: ", ex);
104         }
105     }
106 
107     /**
108      * Handle incoming data during the handshake process. Should consume only the
109      * handshake data from the buffer, leaving any extra data in place.
110      * 
111      * @param nextFilter the next filter
112      * @param buf the server response data buffer
113      */
114     public void messageReceived(final NextFilter nextFilter,
115             final IoBuffer buf) {
116         try {
117             if (buf.remaining() >= SocksProxyConstants.SOCKS_4_RESPONSE_SIZE) {
118                 handleResponse(buf);
119             }
120         } catch (Exception ex) {
121             closeSession("Proxy handshake failed: ", ex);
122         }
123     }
124 
125     /**
126      * Handle a SOCKS4/SOCKS4a response from the proxy server. Test
127      * the response buffer reply code and call {@link #setHandshakeComplete()}
128      * if access is granted.
129      * 
130      * @param buf the buffer holding the server response data.
131      * @throws exception if server response is malformed or if request is rejected
132      * by the proxy server.
133      */
134     protected void handleResponse(final IoBuffer buf) throws Exception {
135         byte first = buf.get(0);
136 
137         if (first != 0) {
138             throw new Exception("Socks response seems to be malformed");
139         }
140 
141         byte status = buf.get(1);
142 
143         // Consumes all the response data from the buffer
144         buf.position(buf.position() + SocksProxyConstants.SOCKS_4_RESPONSE_SIZE);
145         
146         if (status == SocksProxyConstants.V4_REPLY_REQUEST_GRANTED) {
147             setHandshakeComplete();
148         } else {
149             throw new Exception("Proxy handshake failed - Code: 0x"
150                     + ByteUtilities.asHex(new byte[] { status }) + " ("
151                     + SocksProxyConstants.getReplyCodeAsString(status) + ")");
152         }
153     }
154 }