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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.buffer.ByteBufUtil;
21  import io.netty.channel.ChannelHandler.Sharable;
22  import io.netty.channel.ChannelHandlerContext;
23  import io.netty.handler.codec.EncoderException;
24  import io.netty.handler.codec.MessageToByteEncoder;
25  import io.netty.util.internal.ObjectUtil;
26  import io.netty.util.internal.StringUtil;
27  
28  /**
29   * Encodes a server-side {@link Socks5Message} into a {@link ByteBuf}.
30   */
31  @Sharable
32  public class Socks5ServerEncoder extends MessageToByteEncoder<Socks5Message> {
33  
34      public static final Socks5ServerEncoder DEFAULT = new Socks5ServerEncoder(Socks5AddressEncoder.DEFAULT);
35  
36      private final Socks5AddressEncoder addressEncoder;
37  
38      /**
39       * Creates a new instance with the default {@link Socks5AddressEncoder}.
40       */
41      protected Socks5ServerEncoder() {
42          this(Socks5AddressEncoder.DEFAULT);
43      }
44  
45      /**
46       * Creates a new instance with the specified {@link Socks5AddressEncoder}.
47       */
48      public Socks5ServerEncoder(Socks5AddressEncoder addressEncoder) {
49          this.addressEncoder = ObjectUtil.checkNotNull(addressEncoder, "addressEncoder");
50      }
51  
52      /**
53       * Returns the {@link Socks5AddressEncoder} of this encoder.
54       */
55      protected final Socks5AddressEncoder addressEncoder() {
56          return addressEncoder;
57      }
58  
59      @Override
60      protected void encode(ChannelHandlerContext ctx, Socks5Message msg, ByteBuf out) throws Exception {
61          if (msg instanceof Socks5InitialResponse) {
62              encodeAuthMethodResponse((Socks5InitialResponse) msg, out);
63          } else if (msg instanceof Socks5PasswordAuthResponse) {
64              encodePasswordAuthResponse((Socks5PasswordAuthResponse) msg, out);
65          } else if (msg instanceof Socks5CommandResponse) {
66              encodeCommandResponse((Socks5CommandResponse) msg, out);
67          } else {
68              throw new EncoderException("unsupported message type: " + StringUtil.simpleClassName(msg));
69          }
70      }
71  
72      private static void encodeAuthMethodResponse(Socks5InitialResponse msg, ByteBuf out) {
73          out.writeByte(msg.version().byteValue());
74          out.writeByte(msg.authMethod().byteValue());
75      }
76  
77      private static void encodePasswordAuthResponse(Socks5PasswordAuthResponse msg, ByteBuf out) {
78          out.writeByte(0x01);
79          out.writeByte(msg.status().byteValue());
80      }
81  
82      private void encodeCommandResponse(Socks5CommandResponse msg, ByteBuf out) throws Exception {
83          out.writeByte(msg.version().byteValue());
84          out.writeByte(msg.status().byteValue());
85          out.writeByte(0x00);
86  
87          final Socks5AddressType bndAddrType = msg.bndAddrType();
88          out.writeByte(bndAddrType.byteValue());
89          addressEncoder.encodeAddress(bndAddrType, msg.bndAddr(), out);
90  
91          ByteBufUtil.writeShortBE(out, msg.bndPort());
92      }
93  }