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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.SocksInitRequestDecoder.State;
22  
23  import java.util.ArrayList;
24  import java.util.Collections;
25  import java.util.List;
26  
27  /**
28   * Decodes {@link ByteBuf}s into {@link SocksInitRequest}.
29   * Before returning SocksRequest decoder removes itself from pipeline.
30   */
31  public class SocksInitRequestDecoder extends ReplayingDecoder<State> {
32  
33      public SocksInitRequestDecoder() {
34          super(State.CHECK_PROTOCOL_VERSION);
35      }
36  
37      @Override
38      protected void decode(ChannelHandlerContext ctx, ByteBuf byteBuf, List<Object> out) throws Exception {
39          switch (state()) {
40              case CHECK_PROTOCOL_VERSION: {
41                  if (byteBuf.readByte() != SocksProtocolVersion.SOCKS5.byteValue()) {
42                      out.add(SocksCommonUtils.UNKNOWN_SOCKS_REQUEST);
43                      break;
44                  }
45                  checkpoint(State.READ_AUTH_SCHEMES);
46              }
47              case READ_AUTH_SCHEMES: {
48                  final byte authSchemeNum = byteBuf.readByte();
49                  final List<SocksAuthScheme> authSchemes;
50                  if (authSchemeNum > 0) {
51                      authSchemes = new ArrayList<SocksAuthScheme>(authSchemeNum);
52                      for (int i = 0; i < authSchemeNum; i++) {
53                          authSchemes.add(SocksAuthScheme.valueOf(byteBuf.readByte()));
54                      }
55                  } else {
56                      authSchemes = Collections.emptyList();
57                  }
58                  out.add(new SocksInitRequest(authSchemes));
59                  break;
60              }
61              default: {
62                  throw new Error();
63              }
64          }
65          ctx.pipeline().remove(this);
66      }
67  
68      enum State {
69          CHECK_PROTOCOL_VERSION,
70          READ_AUTH_SCHEMES
71      }
72  }