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1   /*
2    * Copyright 2014 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  
17  package io.netty.handler.codec.socksx.v5;
18  
19  import io.netty.buffer.ByteBuf;
20  import io.netty.channel.ChannelHandlerContext;
21  import io.netty.handler.codec.DecoderException;
22  import io.netty.handler.codec.DecoderResult;
23  import io.netty.handler.codec.ReplayingDecoder;
24  import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthResponseDecoder.State;
25  
26  import java.util.List;
27  
28  /**
29   * Decodes a single {@link Socks5PasswordAuthResponse} from the inbound {@link ByteBuf}s.
30   * On successful decode, this decoder will forward the received data to the next handler, so that
31   * other handler can remove or replace this decoder later.  On failed decode, this decoder will
32   * discard the received data, so that other handler closes the connection later.
33   */
34  public class Socks5PasswordAuthResponseDecoder extends ReplayingDecoder<State> {
35  
36      enum State {
37          INIT,
38          SUCCESS,
39          FAILURE
40      }
41  
42      public Socks5PasswordAuthResponseDecoder() {
43          super(State.INIT);
44      }
45  
46      @Override
47      protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
48          try {
49              switch (state()) {
50              case INIT: {
51                  final byte version = in.readByte();
52                  if (version != 1) {
53                      throw new DecoderException("unsupported subnegotiation version: " + version + " (expected: 1)");
54                  }
55  
56                  out.add(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.valueOf(in.readByte())));
57                  checkpoint(State.SUCCESS);
58              }
59              case SUCCESS: {
60                  int readableBytes = actualReadableBytes();
61                  if (readableBytes > 0) {
62                      out.add(in.readSlice(readableBytes).retain());
63                  }
64                  break;
65              }
66              case FAILURE: {
67                  in.skipBytes(actualReadableBytes());
68                  break;
69              }
70              }
71          } catch (Exception e) {
72              fail(out, e);
73          }
74      }
75  
76      private void fail(List<Object> out, Throwable cause) {
77          if (!(cause instanceof DecoderException)) {
78              cause = new DecoderException(cause);
79          }
80  
81          checkpoint(State.FAILURE);
82  
83          Socks5Message m = new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.FAILURE);
84          m.setDecoderResult(DecoderResult.failure(cause));
85          out.add(m);
86      }
87  }