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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    *   https://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  import io.netty.util.internal.UnstableApi;
26  
27  import java.util.List;
28  
29  /**
30   * Decodes a single {@link Socks5PasswordAuthResponse} from the inbound {@link ByteBuf}s.
31   * On successful decode, this decoder will forward the received data to the next handler, so that
32   * other handler can remove or replace this decoder later.  On failed decode, this decoder will
33   * discard the received data, so that other handler closes the connection later.
34   */
35  public class Socks5PasswordAuthResponseDecoder extends ReplayingDecoder<State> {
36  
37      @UnstableApi
38      public enum State {
39          INIT,
40          SUCCESS,
41          FAILURE
42      }
43  
44      public Socks5PasswordAuthResponseDecoder() {
45          super(State.INIT);
46      }
47  
48      @Override
49      protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
50          try {
51              switch (state()) {
52              case INIT: {
53                  final byte version = in.readByte();
54                  if (version != 1) {
55                      throw new DecoderException("unsupported subnegotiation version: " + version + " (expected: 1)");
56                  }
57  
58                  out.add(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.valueOf(in.readByte())));
59                  checkpoint(State.SUCCESS);
60              }
61              case SUCCESS: {
62                  int readableBytes = actualReadableBytes();
63                  if (readableBytes > 0) {
64                      out.add(in.readRetainedSlice(readableBytes));
65                  }
66                  break;
67              }
68              case FAILURE: {
69                  in.skipBytes(actualReadableBytes());
70                  break;
71              }
72              }
73          } catch (Exception e) {
74              fail(out, e);
75          }
76      }
77  
78      private void fail(List<Object> out, Exception cause) {
79          if (!(cause instanceof DecoderException)) {
80              cause = new DecoderException(cause);
81          }
82  
83          checkpoint(State.FAILURE);
84  
85          Socks5Message m = new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.FAILURE);
86          m.setDecoderResult(DecoderResult.failure(cause));
87          out.add(m);
88      }
89  }