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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.codec.socks;
17  
18  import org.jboss.netty.buffer.ChannelBuffer;
19  import org.jboss.netty.channel.Channel;
20  import org.jboss.netty.channel.ChannelHandlerContext;
21  import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
22  
23  import java.util.ArrayList;
24  import java.util.List;
25  
26  /**
27   * Decodes {@link ChannelBuffer}s into {@link SocksInitRequest}.
28   * Before returning SocksRequest decoder removes itself from pipeline.
29   */
30  public class SocksInitRequestDecoder extends ReplayingDecoder<SocksInitRequestDecoder.State> {
31  
32      private final List<SocksMessage.AuthScheme> authSchemes = new ArrayList<SocksMessage.AuthScheme>();
33      private SocksMessage.ProtocolVersion version;
34      private byte authSchemeNum;
35      private SocksRequest msg = SocksCommonUtils.UNKNOWN_SOCKS_REQUEST;
36  
37      public SocksInitRequestDecoder() {
38          super(State.CHECK_PROTOCOL_VERSION);
39      }
40  
41      @Override
42      protected Object decode(ChannelHandlerContext ctx, Channel channel,
43                              ChannelBuffer buffer, State state) throws Exception {
44          switch (state) {
45              case CHECK_PROTOCOL_VERSION: {
46                  version = SocksMessage.ProtocolVersion.fromByte(buffer.readByte());
47                  if (version != SocksMessage.ProtocolVersion.SOCKS5) {
48                      break;
49                  }
50                  checkpoint(State.READ_AUTH_SCHEMES);
51              }
52              case READ_AUTH_SCHEMES: {
53                  authSchemes.clear();
54                  authSchemeNum = buffer.readByte();
55                  for (int i = 0; i < authSchemeNum; i++) {
56                      authSchemes.add(SocksMessage.AuthScheme.fromByte(buffer.readByte()));
57                  }
58                  msg = new SocksInitRequest(authSchemes);
59                  break;
60              }
61          }
62          ctx.getPipeline().remove(this);
63          return msg;
64      }
65  
66      enum State {
67          CHECK_PROTOCOL_VERSION,
68          READ_AUTH_SCHEMES
69      }
70  }