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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.channel.ChannelHandler.Sharable;
21  import io.netty.channel.ChannelHandlerContext;
22  import io.netty.handler.codec.MessageToByteEncoder;
23  import io.netty.util.NetUtil;
24  
25  /**
26   * Encodes a {@link Socks4CommandResponse} into a {@link ByteBuf}.
27   */
28  @Sharable
29  public final class Socks4ServerEncoder extends MessageToByteEncoder<Socks4CommandResponse> {
30  
31      public static final Socks4ServerEncoder INSTANCE = new Socks4ServerEncoder();
32  
33      private static final byte[] IPv4_HOSTNAME_ZEROED = { 0x00, 0x00, 0x00, 0x00 };
34  
35      private Socks4ServerEncoder() { }
36  
37      @Override
38      protected void encode(ChannelHandlerContext ctx, Socks4CommandResponse msg, ByteBuf out) throws Exception {
39          out.writeByte(0);
40          out.writeByte(msg.status().byteValue());
41          out.writeShort(msg.dstPort());
42          out.writeBytes(msg.dstAddr() == null? IPv4_HOSTNAME_ZEROED
43                                              : NetUtil.createByteArrayFromIpAddressString(msg.dstAddr()));
44      }
45  }