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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.v4;
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.MessageToByteEncoder;
24  import io.netty.util.NetUtil;
25  
26  /**
27   * Encodes a {@link Socks4CommandRequest} into a {@link ByteBuf}.
28   */
29  @Sharable
30  public final class Socks4ClientEncoder extends MessageToByteEncoder<Socks4CommandRequest> {
31  
32      /**
33       * The singleton instance of {@link Socks4ClientEncoder}
34       */
35      public static final Socks4ClientEncoder INSTANCE = new Socks4ClientEncoder();
36  
37      private static final byte[] IPv4_DOMAIN_MARKER = {0x00, 0x00, 0x00, 0x01};
38  
39      private Socks4ClientEncoder() { }
40  
41      @Override
42      protected void encode(ChannelHandlerContext ctx, Socks4CommandRequest msg, ByteBuf out) throws Exception {
43          out.writeByte(msg.version().byteValue());
44          out.writeByte(msg.type().byteValue());
45          out.writeShort(msg.dstPort());
46          if (NetUtil.isValidIpV4Address(msg.dstAddr())) {
47              out.writeBytes(NetUtil.createByteArrayFromIpAddressString(msg.dstAddr()));
48              ByteBufUtil.writeAscii(out, msg.userId());
49              out.writeByte(0);
50          } else {
51              out.writeBytes(IPv4_DOMAIN_MARKER);
52              ByteBufUtil.writeAscii(out, msg.userId());
53              out.writeByte(0);
54              ByteBufUtil.writeAscii(out, msg.dstAddr());
55              out.writeByte(0);
56          }
57      }
58  }