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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.parser;
20  
21  import java.nio.ByteBuffer;
22  
23  import org.eclipse.jetty.http2.ErrorCode;
24  import org.eclipse.jetty.http2.frames.PriorityFrame;
25  
26  public class PriorityBodyParser extends BodyParser
27  {
28      private State state = State.PREPARE;
29      private int cursor;
30      private boolean exclusive;
31      private int parentStreamId;
32  
33      public PriorityBodyParser(HeaderParser headerParser, Parser.Listener listener)
34      {
35          super(headerParser, listener);
36      }
37  
38      private void reset()
39      {
40          state = State.PREPARE;
41          cursor = 0;
42          exclusive = false;
43          parentStreamId = 0;
44      }
45  
46      @Override
47      public boolean parse(ByteBuffer buffer)
48      {
49          while (buffer.hasRemaining())
50          {
51              switch (state)
52              {
53                  case PREPARE:
54                  {
55                      // SPEC: wrong streamId is treated as connection error.
56                      if (getStreamId() == 0)
57                          return connectionFailure(buffer, ErrorCode.PROTOCOL_ERROR.code, "invalid_priority_frame");
58                      int length = getBodyLength();
59                      if (length != 5)
60                          return connectionFailure(buffer, ErrorCode.FRAME_SIZE_ERROR.code, "invalid_priority_frame");
61                      state = State.EXCLUSIVE;
62                      break;
63                  }
64                  case EXCLUSIVE:
65                  {
66                      // We must only peek the first byte and not advance the buffer
67                      // because the 31 least significant bits represent the stream id.
68                      int currByte = buffer.get(buffer.position());
69                      exclusive = (currByte & 0x80) == 0x80;
70                      state = State.PARENT_STREAM_ID;
71                      break;
72                  }
73                  case PARENT_STREAM_ID:
74                  {
75                      if (buffer.remaining() >= 4)
76                      {
77                          parentStreamId = buffer.getInt();
78                          parentStreamId &= 0x7F_FF_FF_FF;
79                          state = State.WEIGHT;
80                      }
81                      else
82                      {
83                          state = State.PARENT_STREAM_ID_BYTES;
84                          cursor = 4;
85                      }
86                      break;
87                  }
88                  case PARENT_STREAM_ID_BYTES:
89                  {
90                      int currByte = buffer.get() & 0xFF;
91                      --cursor;
92                      parentStreamId += currByte << (8 * cursor);
93                      if (cursor == 0)
94                      {
95                          parentStreamId &= 0x7F_FF_FF_FF;
96                          state = State.WEIGHT;
97                      }
98                      break;
99                  }
100                 case WEIGHT:
101                 {
102                     // SPEC: stream cannot depend on itself.
103                     if (getStreamId() == parentStreamId)
104                         return connectionFailure(buffer, ErrorCode.PROTOCOL_ERROR.code, "invalid_priority_frame");
105 
106                     int weight = (buffer.get() & 0xFF) + 1;
107                     return onPriority(parentStreamId, weight, exclusive);
108                 }
109                 default:
110                 {
111                     throw new IllegalStateException();
112                 }
113             }
114         }
115         return false;
116     }
117 
118     private boolean onPriority(int parentStreamId, int weight, boolean exclusive)
119     {
120         PriorityFrame frame = new PriorityFrame(getStreamId(), parentStreamId, weight, exclusive);
121         reset();
122         notifyPriority(frame);
123         return true;
124     }
125 
126     private enum State
127     {
128         PREPARE, EXCLUSIVE, PARENT_STREAM_ID, PARENT_STREAM_ID_BYTES, WEIGHT
129     }
130 }