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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.ChannelHandler.Sharable;
21  import io.netty.channel.ChannelHandlerContext;
22  import io.netty.handler.codec.EncoderException;
23  import io.netty.handler.codec.MessageToByteEncoder;
24  import io.netty.util.internal.ObjectUtil;
25  import io.netty.util.internal.StringUtil;
26  
27  /**
28   * Encodes a server-side {@link Socks5Message} into a {@link ByteBuf}.
29   */
30  @Sharable
31  public class Socks5ServerEncoder extends MessageToByteEncoder<Socks5Message> {
32  
33      public static final Socks5ServerEncoder DEFAULT = new Socks5ServerEncoder(Socks5AddressEncoder.DEFAULT);
34  
35      private final Socks5AddressEncoder addressEncoder;
36  
37      /**
38       * Creates a new instance with the default {@link Socks5AddressEncoder}.
39       */
40      protected Socks5ServerEncoder() {
41          this(Socks5AddressEncoder.DEFAULT);
42      }
43  
44      /**
45       * Creates a new instance with the specified {@link Socks5AddressEncoder}.
46       */
47      public Socks5ServerEncoder(Socks5AddressEncoder addressEncoder) {
48          this.addressEncoder = ObjectUtil.checkNotNull(addressEncoder, "addressEncoder");
49      }
50  
51      /**
52       * Returns the {@link Socks5AddressEncoder} of this encoder.
53       */
54      protected final Socks5AddressEncoder addressEncoder() {
55          return addressEncoder;
56      }
57  
58      @Override
59      protected void encode(ChannelHandlerContext ctx, Socks5Message msg, ByteBuf out) throws Exception {
60          if (msg instanceof Socks5InitialResponse) {
61              encodeAuthMethodResponse((Socks5InitialResponse) msg, out);
62          } else if (msg instanceof Socks5PasswordAuthResponse) {
63              encodePasswordAuthResponse((Socks5PasswordAuthResponse) msg, out);
64          } else if (msg instanceof Socks5CommandResponse) {
65              encodeCommandResponse((Socks5CommandResponse) msg, out);
66          } else {
67              throw new EncoderException("unsupported message type: " + StringUtil.simpleClassName(msg));
68          }
69      }
70  
71      private static void encodeAuthMethodResponse(Socks5InitialResponse msg, ByteBuf out) {
72          out.writeByte(msg.version().byteValue());
73          out.writeByte(msg.authMethod().byteValue());
74      }
75  
76      private static void encodePasswordAuthResponse(Socks5PasswordAuthResponse msg, ByteBuf out) {
77          out.writeByte(0x01);
78          out.writeByte(msg.status().byteValue());
79      }
80  
81      private void encodeCommandResponse(Socks5CommandResponse msg, ByteBuf out) throws Exception {
82          out.writeByte(msg.version().byteValue());
83          out.writeByte(msg.status().byteValue());
84          out.writeByte(0x00);
85  
86          final Socks5AddressType bndAddrType = msg.bndAddrType();
87          out.writeByte(bndAddrType.byteValue());
88          addressEncoder.encodeAddress(bndAddrType, msg.bndAddr(), out);
89  
90          out.writeShort(msg.bndPort());
91      }
92  }