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 The Apache MINA Project (dev@mina.apache.org)
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)
55 throws Exception {
56 int beginPos = in.position();
57 int limit = in.limit();
58 int terminatorPos = -1;
59
60 for (int i = beginPos; i < limit; i++) {
61 byte b = in.get(i);
62 if (b == CR) {
63 lastIsCR = true;
64 } else {
65 if (b == LF && lastIsCR) {
66 terminatorPos = i;
67 break;
68 }
69 lastIsCR = false;
70 }
71 }
72
73 if (terminatorPos >= 0) {
74 IoBuffer product;
75
76 int endPos = terminatorPos - 1;
77
78 if (beginPos < endPos) {
79 in.limit(endPos);
80
81 if (buffer == null) {
82 product = in.slice();
83 } else {
84 buffer.put(in);
85 product = buffer.flip();
86 buffer = null;
87 }
88
89 in.limit(limit);
90 } else {
91 // When input contained only CR or LF rather than actual data...
92 if (buffer == null) {
93 product = IoBuffer.allocate(0);
94 } else {
95 product = buffer.flip();
96 buffer = null;
97 }
98 }
99 in.position(terminatorPos + 1);
100 return finishDecode(product, out);
101 }
102
103 in.position(beginPos);
104
105 if (buffer == null) {
106 buffer = IoBuffer.allocate(in.remaining());
107 buffer.setAutoExpand(true);
108 }
109
110 buffer.put(in);
111
112 if (lastIsCR) {
113 buffer.position(buffer.position() - 1);
114 }
115
116 return this;
117 }
118
119 /**
120 * {@inheritDoc}
121 */
122 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
123 IoBuffer product;
124 // When input contained only CR or LF rather than actual data...
125 if (buffer == null) {
126 product = IoBuffer.allocate(0);
127 } else {
128 product = buffer.flip();
129 buffer = null;
130 }
131 return finishDecode(product, out);
132 }
133
134 /**
135 * Invoked when this state has reached a <code>CRLF</code>.
136 *
137 * @param product the read bytes including the <code>CRLF</code>.
138 * @param out the current {@link ProtocolDecoderOutput} used to write
139 * decoded messages.
140 * @return the next state if a state transition was triggered (use
141 * <code>this</code> for loop transitions) or <code>null</code> if
142 * the state machine has reached its end.
143 * @throws Exception if the read data violated protocol specification.
144 */
145 protected abstract DecodingState finishDecode(IoBuffer product,
146 ProtocolDecoderOutput out) throws Exception;
147 }