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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  import java.util.List;
29  import java.util.RandomAccess;
30  
31  /**
32   * Encodes a client-side {@link Socks5Message} into a {@link ByteBuf}.
33   */
34  @Sharable
35  public class Socks5ClientEncoder extends MessageToByteEncoder<Socks5Message> {
36  
37      public static final Socks5ClientEncoder DEFAULT = new Socks5ClientEncoder();
38  
39      private final Socks5AddressEncoder addressEncoder;
40  
41      /**
42       * Creates a new instance with the default {@link Socks5AddressEncoder}.
43       */
44      protected Socks5ClientEncoder() {
45          this(Socks5AddressEncoder.DEFAULT);
46      }
47  
48      /**
49       * Creates a new instance with the specified {@link Socks5AddressEncoder}.
50       */
51      public Socks5ClientEncoder(Socks5AddressEncoder addressEncoder) {
52          this.addressEncoder = ObjectUtil.checkNotNull(addressEncoder, "addressEncoder");
53      }
54  
55      /**
56       * Returns the {@link Socks5AddressEncoder} of this encoder.
57       */
58      protected final Socks5AddressEncoder addressEncoder() {
59          return addressEncoder;
60      }
61  
62      @Override
63      protected void encode(ChannelHandlerContext ctx, Socks5Message msg, ByteBuf out) throws Exception {
64          if (msg instanceof Socks5InitialRequest) {
65              encodeAuthMethodRequest((Socks5InitialRequest) msg, out);
66          } else if (msg instanceof Socks5PasswordAuthRequest) {
67              encodePasswordAuthRequest((Socks5PasswordAuthRequest) msg, out);
68          } else if (msg instanceof Socks5CommandRequest) {
69              encodeCommandRequest((Socks5CommandRequest) msg, out);
70          } else {
71              throw new EncoderException("unsupported message type: " + StringUtil.simpleClassName(msg));
72          }
73      }
74  
75      private static void encodeAuthMethodRequest(Socks5InitialRequest msg, ByteBuf out) {
76          out.writeByte(msg.version().byteValue());
77  
78          final List<Socks5AuthMethod> authMethods = msg.authMethods();
79          final int numAuthMethods = authMethods.size();
80          out.writeByte(numAuthMethods);
81  
82          if (authMethods instanceof RandomAccess) {
83              for (int i = 0; i < numAuthMethods; i ++) {
84                  out.writeByte(authMethods.get(i).byteValue());
85              }
86          } else {
87              for (Socks5AuthMethod a: authMethods) {
88                  out.writeByte(a.byteValue());
89              }
90          }
91      }
92  
93      private static void encodePasswordAuthRequest(Socks5PasswordAuthRequest msg, ByteBuf out) {
94          out.writeByte(0x01);
95  
96          final String username = msg.username();
97          out.writeByte(username.length());
98          ByteBufUtil.writeAscii(out, username);
99  
100         final String password = msg.password();
101         out.writeByte(password.length());
102         ByteBufUtil.writeAscii(out, password);
103     }
104 
105     private void encodeCommandRequest(Socks5CommandRequest msg, ByteBuf out) throws Exception {
106         out.writeByte(msg.version().byteValue());
107         out.writeByte(msg.type().byteValue());
108         out.writeByte(0x00);
109 
110         final Socks5AddressType dstAddrType = msg.dstAddrType();
111         out.writeByte(dstAddrType.byteValue());
112         addressEncoder.encodeAddress(dstAddrType, msg.dstAddr(), out);
113         out.writeShort(msg.dstPort());
114     }
115 }