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   /*
    * Copyright 2019 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.http.websocketx;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.http.DefaultFullHttpResponse;
  import io.netty.handler.codec.http.HttpHeaderNames;
  import io.netty.handler.codec.http.HttpUtil;
  import io.netty.handler.codec.http.HttpRequest;
  import io.netty.handler.codec.http.HttpResponse;
  import io.netty.handler.codec.http.HttpResponseStatus;
  import io.netty.handler.codec.http.HttpVersion;
  import io.netty.util.internal.ObjectUtil;
  
  /**
   * Auto-detects the version of the Web Socket protocol in use and creates a new proper
   * {@link WebSocketServerHandshaker}.
   */
  public class WebSocketServerHandshakerFactory {
  
      private final String webSocketURL;
  
      private final String subprotocols;
  
      private final WebSocketDecoderConfig decoderConfig;
  
      /**
       * Constructor specifying the destination web socket location
       *
       * @param webSocketURL
       *            URL for web socket communications. e.g "ws://myhost.com/mypath".
       *            Subsequent web socket frames will be sent to this URL.
       * @param subprotocols
       *            CSV of supported protocols. Null if sub protocols not supported.
       * @param allowExtensions
       *            Allow extensions to be used in the reserved bits of the web socket frame
       */
      public WebSocketServerHandshakerFactory(
              String webSocketURL, String subprotocols, boolean allowExtensions) {
          this(webSocketURL, subprotocols, allowExtensions, 65536);
      }
  
      /**
       * Constructor specifying the destination web socket location
       *
       * @param webSocketURL
       *            URL for web socket communications. e.g "ws://myhost.com/mypath".
       *            Subsequent web socket frames will be sent to this URL.
       * @param subprotocols
       *            CSV of supported protocols. Null if sub protocols not supported.
       * @param allowExtensions
       *            Allow extensions to be used in the reserved bits of the web socket frame
       * @param maxFramePayloadLength
       *            Maximum allowable frame payload length. Setting this value to your application's
       *            requirement may reduce denial of service attacks using long data frames.
       */
      public WebSocketServerHandshakerFactory(
              String webSocketURL, String subprotocols, boolean allowExtensions,
              int maxFramePayloadLength) {
          this(webSocketURL, subprotocols, allowExtensions, maxFramePayloadLength, false);
      }
  
      /**
       * Constructor specifying the destination web socket location
       *
       * @param webSocketURL
       *            URL for web socket communications. e.g "ws://myhost.com/mypath".
       *            Subsequent web socket frames will be sent to this URL.
       * @param subprotocols
       *            CSV of supported protocols. Null if sub protocols not supported.
       * @param allowExtensions
       *            Allow extensions to be used in the reserved bits of the web socket frame
       * @param maxFramePayloadLength
       *            Maximum allowable frame payload length. Setting this value to your application's
       *            requirement may reduce denial of service attacks using long data frames.
       * @param allowMaskMismatch
       *            When set to true, frames which are not masked properly according to the standard will still be
       *            accepted.
       */
      public WebSocketServerHandshakerFactory(
              String webSocketURL, String subprotocols, boolean allowExtensions,
              int maxFramePayloadLength, boolean allowMaskMismatch) {
          this(webSocketURL, subprotocols, WebSocketDecoderConfig.newBuilder()
              .allowExtensions(allowExtensions)
             .maxFramePayloadLength(maxFramePayloadLength)
             .allowMaskMismatch(allowMaskMismatch)
             .build());
     }
 
     /**
      * Constructor specifying the destination web socket location
      *
      * @param webSocketURL
      *            URL for web socket communications. e.g "ws://myhost.com/mypath".
      *            Subsequent web socket frames will be sent to this URL.
      * @param subprotocols
      *            CSV of supported protocols. Null if sub protocols not supported.
      * @param decoderConfig
      *            Frames decoder options.
      */
     public WebSocketServerHandshakerFactory(
             String webSocketURL, String subprotocols, WebSocketDecoderConfig decoderConfig) {
         this.webSocketURL = webSocketURL;
         this.subprotocols = subprotocols;
         this.decoderConfig = ObjectUtil.checkNotNull(decoderConfig, "decoderConfig");
     }
 
     /**
      * Instances a new handshaker
      *
      * @return A new WebSocketServerHandshaker for the requested web socket version. Null if web
      *         socket version is not supported.
      */
     public WebSocketServerHandshaker newHandshaker(HttpRequest req) {
 
         CharSequence version = req.headers().get(HttpHeaderNames.SEC_WEBSOCKET_VERSION);
         if (version != null) {
             if (version.equals(WebSocketVersion.V13.toHttpHeaderValue())) {
                 // Version 13 of the wire protocol - RFC 6455 (version 17 of the draft hybi specification).
                 return new WebSocketServerHandshaker13(
                         webSocketURL, subprotocols, decoderConfig);
             } else if (version.equals(WebSocketVersion.V08.toHttpHeaderValue())) {
                 // Version 8 of the wire protocol - version 10 of the draft hybi specification.
                 return new WebSocketServerHandshaker08(
                         webSocketURL, subprotocols, decoderConfig);
             } else if (version.equals(WebSocketVersion.V07.toHttpHeaderValue())) {
                 // Version 8 of the wire protocol - version 07 of the draft hybi specification.
                 return new WebSocketServerHandshaker07(
                         webSocketURL, subprotocols, decoderConfig);
             } else {
                 return null;
             }
         } else {
             // Assume version 00 where version header was not specified
             return new WebSocketServerHandshaker00(webSocketURL, subprotocols, decoderConfig);
         }
     }
 
     /**
      * @deprecated use {@link #sendUnsupportedVersionResponse(Channel)}
      */
     @Deprecated
     public static void sendUnsupportedWebSocketVersionResponse(Channel channel) {
         sendUnsupportedVersionResponse(channel);
     }
 
     /**
      * Return that we need cannot support the web socket version
      */
     public static ChannelFuture sendUnsupportedVersionResponse(Channel channel) {
         return sendUnsupportedVersionResponse(channel, channel.newPromise());
     }
 
     /**
      * Return that we need cannot support the web socket version
      */
     public static ChannelFuture sendUnsupportedVersionResponse(Channel channel, ChannelPromise promise) {
         HttpResponse res = new DefaultFullHttpResponse(
                 HttpVersion.HTTP_1_1,
                 HttpResponseStatus.UPGRADE_REQUIRED, channel.alloc().buffer(0));
         res.headers().set(HttpHeaderNames.SEC_WEBSOCKET_VERSION, WebSocketVersion.V13.toHttpHeaderValue());
         HttpUtil.setContentLength(res, 0);
         return channel.writeAndFlush(res, promise);
     }
 }