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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  /**
24   * Decodes {@link ChannelBuffer}s into {@link SocksInitResponse}.
25   * Before returning SocksResponse decoder removes itself from pipeline.
26   */
27  public class SocksInitResponseDecoder extends ReplayingDecoder<SocksInitResponseDecoder.State> {
28  
29      private SocksMessage.ProtocolVersion version;
30      private SocksMessage.AuthScheme authScheme;
31  
32      private SocksResponse msg = SocksCommonUtils.UNKNOWN_SOCKS_RESPONSE;
33  
34      public SocksInitResponseDecoder() {
35          super(State.CHECK_PROTOCOL_VERSION);
36      }
37  
38      @Override
39      protected Object decode(ChannelHandlerContext ctx, Channel channel,
40                              ChannelBuffer buffer, State state) throws Exception {
41          switch (state) {
42              case CHECK_PROTOCOL_VERSION: {
43                  version = SocksMessage.ProtocolVersion.fromByte(buffer.readByte());
44                  if (version != SocksMessage.ProtocolVersion.SOCKS5) {
45                      break;
46                  }
47                  checkpoint(State.READ_PREFFERED_AUTH_TYPE);
48              }
49              case READ_PREFFERED_AUTH_TYPE: {
50                  authScheme = SocksMessage.AuthScheme.fromByte(buffer.readByte());
51                  msg = new SocksInitResponse(authScheme);
52                  break;
53              }
54          }
55          ctx.getPipeline().remove(this);
56          return msg;
57      }
58  
59      public enum State {
60          CHECK_PROTOCOL_VERSION,
61          READ_PREFFERED_AUTH_TYPE
62      }
63  }