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1   //
2   //  ========================================================================
3   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
4   //  ------------------------------------------------------------------------
5   //  All rights reserved. This program and the accompanying materials
6   //  are made available under the terms of the Eclipse Public License v1.0
7   //  and Apache License v2.0 which accompanies this distribution.
8   //
9   //      The Eclipse Public License is available at
10  //      http://www.eclipse.org/legal/epl-v10.html
11  //
12  //      The Apache License v2.0 is available at
13  //      http://www.opensource.org/licenses/apache2.0.php
14  //
15  //  You may elect to redistribute this code under either of these licenses.
16  //  ========================================================================
17  //
18  
19  package org.eclipse.jetty.http2.generator;
20  
21  import java.nio.ByteBuffer;
22  
23  import org.eclipse.jetty.http.MetaData;
24  import org.eclipse.jetty.http2.Flags;
25  import org.eclipse.jetty.http2.frames.Frame;
26  import org.eclipse.jetty.http2.frames.FrameType;
27  import org.eclipse.jetty.http2.frames.PushPromiseFrame;
28  import org.eclipse.jetty.http2.hpack.HpackEncoder;
29  import org.eclipse.jetty.io.ByteBufferPool;
30  import org.eclipse.jetty.util.BufferUtil;
31  
32  public class PushPromiseGenerator extends FrameGenerator
33  {
34      private final HpackEncoder encoder;
35  
36      public PushPromiseGenerator(HeaderGenerator headerGenerator, HpackEncoder encoder)
37      {
38          super(headerGenerator);
39          this.encoder = encoder;
40      }
41  
42      @Override
43      public void generate(ByteBufferPool.Lease lease, Frame frame)
44      {
45          PushPromiseFrame pushPromiseFrame = (PushPromiseFrame)frame;
46          generatePushPromise(lease, pushPromiseFrame.getStreamId(), pushPromiseFrame.getPromisedStreamId(), pushPromiseFrame.getMetaData());
47      }
48  
49      public void generatePushPromise(ByteBufferPool.Lease lease, int streamId, int promisedStreamId, MetaData metaData)
50      {
51          if (streamId < 0)
52              throw new IllegalArgumentException("Invalid stream id: " + streamId);
53          if (promisedStreamId < 0)
54              throw new IllegalArgumentException("Invalid promised stream id: " + promisedStreamId);
55  
56          int maxFrameSize = getMaxFrameSize();
57          // The promised streamId space.
58          int extraSpace = 4;
59          maxFrameSize -= extraSpace;
60  
61          ByteBuffer hpacked = lease.acquire(maxFrameSize, false);
62          BufferUtil.clearToFill(hpacked);
63          encoder.encode(hpacked, metaData);
64          int hpackedLength = hpacked.position();
65          BufferUtil.flipToFlush(hpacked, 0);
66  
67          int length = hpackedLength + extraSpace;
68          int flags = Flags.END_HEADERS;
69  
70          ByteBuffer header = generateHeader(lease, FrameType.PUSH_PROMISE, length, flags, streamId);
71          header.putInt(promisedStreamId);
72          BufferUtil.flipToFlush(header, 0);
73  
74          lease.append(header, true);
75          lease.append(hpacked, true);
76      }
77  }