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1   /*
2    * Copyright 2013 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  package io.netty.handler.codec.http.websocketx;
17  
18  
19  import io.netty.channel.ChannelHandlerContext;
20  import io.netty.handler.codec.MessageToMessageDecoder;
21  
22  import java.util.List;
23  
24  abstract class WebSocketProtocolHandler extends MessageToMessageDecoder<WebSocketFrame> {
25  
26      private final boolean dropPongFrames;
27  
28      /**
29       * Creates a new {@link WebSocketProtocolHandler} that will <i>drop</i> {@link PongWebSocketFrame}s.
30       */
31      WebSocketProtocolHandler() {
32          this(true);
33      }
34  
35      /**
36       * Creates a new {@link WebSocketProtocolHandler}, given a parameter that determines whether or not to drop {@link
37       * PongWebSocketFrame}s.
38       *
39       * @param dropPongFrames
40       *            {@code true} if {@link PongWebSocketFrame}s should be dropped
41       */
42      WebSocketProtocolHandler(boolean dropPongFrames) {
43          this.dropPongFrames = dropPongFrames;
44      }
45  
46      @Override
47      protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception {
48          if (frame instanceof PingWebSocketFrame) {
49              frame.content().retain();
50              ctx.channel().writeAndFlush(new PongWebSocketFrame(frame.content()));
51              return;
52          }
53          if (frame instanceof PongWebSocketFrame && dropPongFrames) {
54              return;
55          }
56  
57          out.add(frame.retain());
58      }
59  
60      @Override
61      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
62          ctx.fireExceptionCaught(cause);
63          ctx.close();
64      }
65  }