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   /*
    * Copyright 2016 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.haproxy;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.DefaultByteBufHolder;
  import io.netty.util.internal.StringUtil;
  
  import static io.netty.util.internal.ObjectUtil.*;
  
  /**
   * A Type-Length Value (TLV vector) that can be added to the PROXY protocol
   * to include additional information like SSL information.
   *
   * @see HAProxySSLTLV
   */
  public class HAProxyTLV extends DefaultByteBufHolder {
  
      private final Type type;
      private final byte typeByteValue;
  
      /**
       * The size of this tlv in bytes.
       * @return the number of bytes.
       */
      int totalNumBytes() {
          return 3 + contentNumBytes(); // type(1) + length(2) + content
      }
  
      int contentNumBytes() {
          return content().readableBytes();
      }
  
      /**
       * The registered types a TLV can have regarding the PROXY protocol 1.5 spec
       */
      public enum Type {
          PP2_TYPE_ALPN,
          PP2_TYPE_AUTHORITY,
          PP2_TYPE_SSL,
          PP2_TYPE_SSL_VERSION,
          PP2_TYPE_SSL_CN,
          PP2_TYPE_NETNS,
          /**
           * A TLV type that is not officially defined in the spec. May be used for nonstandard TLVs
           */
          OTHER;
  
          /**
           * Returns the {@link Type} for a specific byte value as defined in the PROXY protocol 1.5 spec
           * <p>
           * If the byte value is not an official one, it will return {@link Type#OTHER}.
           *
           * @param byteValue the byte for a type
           *
           * @return the {@link Type} of a TLV
           */
          public static Type typeForByteValue(byte byteValue) {
              switch (byteValue) {
              case 0x01:
                  return PP2_TYPE_ALPN;
              case 0x02:
                  return PP2_TYPE_AUTHORITY;
              case 0x20:
                  return PP2_TYPE_SSL;
              case 0x21:
                  return PP2_TYPE_SSL_VERSION;
              case 0x22:
                  return PP2_TYPE_SSL_CN;
              case 0x30:
                  return PP2_TYPE_NETNS;
              default:
                  return OTHER;
              }
          }
  
          /**
           * Returns the byte value for the {@link Type} as defined in the PROXY protocol 1.5 spec.
           *
           * @param type the {@link Type}
           *
           * @return the byte value of the {@link Type}.
           */
          public static byte byteValueForType(Type type) {
              switch (type) {
             case PP2_TYPE_ALPN:
                 return 0x01;
             case PP2_TYPE_AUTHORITY:
                 return 0x02;
             case PP2_TYPE_SSL:
                 return 0x20;
             case PP2_TYPE_SSL_VERSION:
                 return 0x21;
             case PP2_TYPE_SSL_CN:
                 return 0x22;
             case PP2_TYPE_NETNS:
                 return 0x30;
             default:
                 throw new IllegalArgumentException("unknown type: " + type);
             }
         }
     }
 
     /**
      * Creates a new HAProxyTLV
      *
      * @param typeByteValue the byteValue of the TLV. This is especially important if non-standard TLVs are used
      * @param content the raw content of the TLV
      */
     public HAProxyTLV(byte typeByteValue, ByteBuf content) {
         this(Type.typeForByteValue(typeByteValue), typeByteValue, content);
     }
 
     /**
      * Creates a new HAProxyTLV
      *
      * @param type the {@link Type} of the TLV
      * @param content the raw content of the TLV
      */
     public HAProxyTLV(Type type, ByteBuf content) {
         this(type, Type.byteValueForType(type), content);
     }
 
     /**
      * Creates a new HAProxyTLV
      *
      * @param type the {@link Type} of the TLV
      * @param typeByteValue the byteValue of the TLV. This is especially important if non-standard TLVs are used
      * @param content the raw content of the TLV
      */
     HAProxyTLV(final Type type, final byte typeByteValue, final ByteBuf content) {
         super(content);
         this.type = checkNotNull(type, "type");
         this.typeByteValue = typeByteValue;
     }
 
     /**
      * Returns the {@link Type} of this TLV
      */
     public Type type() {
         return type;
     }
 
     /**
      * Returns the type of the TLV as byte
      */
     public byte typeByteValue() {
         return typeByteValue;
     }
 
     @Override
     public HAProxyTLV copy() {
         return replace(content().copy());
     }
 
     @Override
     public HAProxyTLV duplicate() {
         return replace(content().duplicate());
     }
 
     @Override
     public HAProxyTLV retainedDuplicate() {
         return replace(content().retainedDuplicate());
     }
 
     @Override
     public HAProxyTLV replace(ByteBuf content) {
         return new HAProxyTLV(type, typeByteValue, content);
     }
 
     @Override
     public HAProxyTLV retain() {
         super.retain();
         return this;
     }
 
     @Override
     public HAProxyTLV retain(int increment) {
         super.retain(increment);
         return this;
     }
 
     @Override
     public HAProxyTLV touch() {
         super.touch();
         return this;
     }
 
     @Override
     public HAProxyTLV touch(Object hint) {
         super.touch(hint);
         return this;
     }
 
     @Override
     public String toString() {
         return StringUtil.simpleClassName(this) +
                "(type: " + type() +
                ", typeByteValue: " + typeByteValue() +
                ", content: " + contentToString() + ')';
     }
 }