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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 io.netty.handler.codec.socks;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.channel.ChannelHandlerContext;
20  import io.netty.handler.codec.ReplayingDecoder;
21  import io.netty.handler.codec.socks.SocksInitResponseDecoder.State;
22  
23  import java.util.List;
24  
25  /**
26   * Decodes {@link ByteBuf}s into {@link SocksInitResponse}.
27   * Before returning SocksResponse decoder removes itself from pipeline.
28   */
29  public class SocksInitResponseDecoder extends ReplayingDecoder<State> {
30  
31      public SocksInitResponseDecoder() {
32          super(State.CHECK_PROTOCOL_VERSION);
33      }
34  
35      @Override
36      protected void decode(ChannelHandlerContext ctx, ByteBuf byteBuf, List<Object> out) throws Exception {
37          switch (state()) {
38              case CHECK_PROTOCOL_VERSION: {
39                  if (byteBuf.readByte() != SocksProtocolVersion.SOCKS5.byteValue()) {
40                      out.add(SocksCommonUtils.UNKNOWN_SOCKS_RESPONSE);
41                      break;
42                  }
43                  checkpoint(State.READ_PREFERRED_AUTH_TYPE);
44              }
45              case READ_PREFERRED_AUTH_TYPE: {
46                  SocksAuthScheme authScheme = SocksAuthScheme.valueOf(byteBuf.readByte());
47                  out.add(new SocksInitResponse(authScheme));
48                  break;
49              }
50              default: {
51                  throw new Error();
52              }
53          }
54          ctx.pipeline().remove(this);
55      }
56  
57      enum State {
58          CHECK_PROTOCOL_VERSION,
59          READ_PREFERRED_AUTH_TYPE
60      }
61  }