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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      private static final String name = "SOCKS_INIT_RESPONSE_DECODER";
31  
32      /**
33       * @deprecated Will be removed at the next minor version bump.
34       */
35      @Deprecated
36      public static String getName() {
37          return name;
38      }
39  
40      public SocksInitResponseDecoder() {
41          super(State.CHECK_PROTOCOL_VERSION);
42      }
43  
44      @Override
45      protected void decode(ChannelHandlerContext ctx, ByteBuf byteBuf, List<Object> out) throws Exception {
46          switch (state()) {
47              case CHECK_PROTOCOL_VERSION: {
48                  if (byteBuf.readByte() != SocksProtocolVersion.SOCKS5.byteValue()) {
49                      out.add(SocksCommonUtils.UNKNOWN_SOCKS_RESPONSE);
50                      break;
51                  }
52                  checkpoint(State.READ_PREFERRED_AUTH_TYPE);
53              }
54              case READ_PREFERRED_AUTH_TYPE: {
55                  SocksAuthScheme authScheme = SocksAuthScheme.valueOf(byteBuf.readByte());
56                  out.add(new SocksInitResponse(authScheme));
57                  break;
58              }
59              default: {
60                  throw new Error();
61              }
62          }
63          ctx.pipeline().remove(this);
64      }
65  
66      enum State {
67          CHECK_PROTOCOL_VERSION,
68          READ_PREFERRED_AUTH_TYPE
69      }
70  }