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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  package io.netty.example.spdy.client;
17  
18  import io.netty.channel.ChannelHandlerAdapter;
19  import io.netty.channel.ChannelHandlerContext;
20  import io.netty.channel.ChannelPromise;
21  import io.netty.handler.codec.http.HttpMessage;
22  import io.netty.handler.codec.spdy.SpdyHttpHeaders;
23  import io.netty.handler.codec.spdy.SpdyHttpHeaders.Names;
24  
25  /**
26   * Adds a unique client stream ID to the SPDY header. Client stream IDs MUST be odd.
27   */
28  public class SpdyClientStreamIdHandler extends ChannelHandlerAdapter {
29  
30      private int currentStreamId = 1;
31  
32      public boolean acceptOutboundMessage(Object msg) {
33          return msg instanceof HttpMessage;
34      }
35  
36      @Override
37      public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
38          if (acceptOutboundMessage(msg)) {
39              HttpMessage httpMsg = (HttpMessage) msg;
40              if (!httpMsg.headers().contains(SpdyHttpHeaders.Names.STREAM_ID)) {
41                  httpMsg.headers().setInt(Names.STREAM_ID, currentStreamId);
42                  // Client stream IDs are always odd
43                  currentStreamId += 2;
44              }
45          }
46          ctx.write(msg, promise);
47      }
48  }