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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.filter.codec.statemachine;
21  
22  import org.apache.mina.core.buffer.IoBuffer;
23  import org.apache.mina.filter.codec.ProtocolDecoderOutput;
24  
25  /**
26   * {@link DecodingState} which consumes all bytes until a <code>CRLF</code> 
27   * has been encountered.
28   * 
29   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
30   */
31  public abstract class ConsumeToCrLfDecodingState implements DecodingState {
32  
33      /**
34       * Carriage return character
35       */
36      private static final byte CR = 13;
37  
38      /**
39       * Line feed character
40       */
41      private static final byte LF = 10;
42  
43      private boolean lastIsCR;
44  
45      private IoBuffer buffer;
46  
47      /**
48       * Creates a new instance.
49       */
50      public ConsumeToCrLfDecodingState() {
51          // Do nothing
52      }
53  
54      public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
55          int beginPos = in.position();
56          int limit = in.limit();
57          int terminatorPos = -1;
58  
59          for (int i = beginPos; i < limit; i++) {
60              byte b = in.get(i);
61              if (b == CR) {
62                  lastIsCR = true;
63              } else {
64                  if (b == LF && lastIsCR) {
65                      terminatorPos = i;
66                      break;
67                  }
68                  lastIsCR = false;
69              }
70          }
71  
72          if (terminatorPos >= 0) {
73              IoBuffer product;
74  
75              int endPos = terminatorPos - 1;
76  
77              if (beginPos < endPos) {
78                  in.limit(endPos);
79  
80                  if (buffer == null) {
81                      product = in.slice();
82                  } else {
83                      buffer.put(in);
84                      product = buffer.flip();
85                      buffer = null;
86                  }
87  
88                  in.limit(limit);
89              } else {
90                  // When input contained only CR or LF rather than actual data...
91                  if (buffer == null) {
92                      product = IoBuffer.allocate(0);
93                  } else {
94                      product = buffer.flip();
95                      buffer = null;
96                  }
97              }
98              in.position(terminatorPos + 1);
99              return finishDecode(product, out);
100         }
101 
102         in.position(beginPos);
103 
104         if (buffer == null) {
105             buffer = IoBuffer.allocate(in.remaining());
106             buffer.setAutoExpand(true);
107         }
108 
109         buffer.put(in);
110 
111         if (lastIsCR) {
112             buffer.position(buffer.position() - 1);
113         }
114 
115         return this;
116     }
117 
118     /**
119      * {@inheritDoc}
120      */
121     public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
122         IoBuffer product;
123         // When input contained only CR or LF rather than actual data...
124         if (buffer == null) {
125             product = IoBuffer.allocate(0);
126         } else {
127             product = buffer.flip();
128             buffer = null;
129         }
130         return finishDecode(product, out);
131     }
132 
133     /**
134      * Invoked when this state has reached a <code>CRLF</code>.
135      * 
136      * @param product the read bytes including the <code>CRLF</code>.
137      * @param out the current {@link ProtocolDecoderOutput} used to write 
138      *        decoded messages.
139      * @return the next state if a state transition was triggered (use 
140      *         <code>this</code> for loop transitions) or <code>null</code> if 
141      *         the state machine has reached its end.
142      * @throws Exception if the read data violated protocol specification.
143      */
144     protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception;
145 }