/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  
  package io.netty.handler.codec.socksx.v4;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufUtil;
  import io.netty.channel.ChannelHandler.Sharable;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.MessageToByteEncoder;
  import io.netty.util.NetUtil;
  
  /**
   * Encodes a {@link Socks4CommandResponse} into a {@link ByteBuf}.
   */
  @Sharable
  public final class Socks4ServerEncoder extends MessageToByteEncoder<Socks4CommandResponse> {
  
      public static final Socks4ServerEncoder INSTANCE = new Socks4ServerEncoder();
  
      private static final byte[] IPv4_HOSTNAME_ZEROED = { 0x00, 0x00, 0x00, 0x00 };
  
      private Socks4ServerEncoder() { }
  
      @Override
      protected void encode(ChannelHandlerContext ctx, Socks4CommandResponse msg, ByteBuf out) throws Exception {
          out.writeByte(0);
          out.writeByte(msg.status().byteValue());
          ByteBufUtil.writeShortBE(out, msg.dstPort());
          out.writeBytes(msg.dstAddr() == null? IPv4_HOSTNAME_ZEROED
                                              : NetUtil.createByteArrayFromIpAddressString(msg.dstAddr()));
      }
  }