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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.SocksCmdRequestDecoder.State;
22  
23  import java.util.List;
24  
25  /**
26   * Decodes {@link ByteBuf}s into {@link SocksCmdRequest}.
27   * Before returning SocksRequest decoder removes itself from pipeline.
28   */
29  public class SocksCmdRequestDecoder extends ReplayingDecoder<State> {
30      private static final String name = "SOCKS_CMD_REQUEST_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      private SocksCmdType cmdType;
41      private SocksAddressType addressType;
42  
43      public SocksCmdRequestDecoder() {
44          super(State.CHECK_PROTOCOL_VERSION);
45      }
46  
47      @Override
48      protected void decode(ChannelHandlerContext ctx, ByteBuf byteBuf, List<Object> out) throws Exception {
49          switch (state()) {
50              case CHECK_PROTOCOL_VERSION: {
51                  if (byteBuf.readByte() != SocksProtocolVersion.SOCKS5.byteValue()) {
52                      out.add(SocksCommonUtils.UNKNOWN_SOCKS_REQUEST);
53                      break;
54                  }
55                  checkpoint(State.READ_CMD_HEADER);
56              }
57              case READ_CMD_HEADER: {
58                  cmdType = SocksCmdType.valueOf(byteBuf.readByte());
59                  byteBuf.skipBytes(1); // reserved
60                  addressType = SocksAddressType.valueOf(byteBuf.readByte());
61                  checkpoint(State.READ_CMD_ADDRESS);
62              }
63              case READ_CMD_ADDRESS: {
64                  switch (addressType) {
65                      case IPv4: {
66                          String host = SocksCommonUtils.intToIp(byteBuf.readInt());
67                          int port = byteBuf.readUnsignedShort();
68                          out.add(new SocksCmdRequest(cmdType, addressType, host, port));
69                          break;
70                      }
71                      case DOMAIN: {
72                          int fieldLength = byteBuf.readByte();
73                          String host = SocksCommonUtils.readUsAscii(byteBuf, fieldLength);
74                          int port = byteBuf.readUnsignedShort();
75                          out.add(new SocksCmdRequest(cmdType, addressType, host, port));
76                          break;
77                      }
78                      case IPv6: {
79                          byte[] bytes = new byte[16];
80                          byteBuf.readBytes(bytes);
81                          String host = SocksCommonUtils.ipv6toStr(bytes);
82                          int port = byteBuf.readUnsignedShort();
83                          out.add(new SocksCmdRequest(cmdType, addressType, host, port));
84                          break;
85                      }
86                      case UNKNOWN: {
87                          out.add(SocksCommonUtils.UNKNOWN_SOCKS_REQUEST);
88                          break;
89                      }
90                      default: {
91                          throw new Error();
92                      }
93                  }
94                  break;
95              }
96              default: {
97                  throw new Error();
98              }
99          }
100         ctx.pipeline().remove(this);
101     }
102 
103     enum State {
104         CHECK_PROTOCOL_VERSION,
105         READ_CMD_HEADER,
106         READ_CMD_ADDRESS
107     }
108 }