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 /**
55 * {@inheritDoc}
56 */
57 @Override
58 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
59 int beginPos = in.position();
60 int limit = in.limit();
61 int terminatorPos = -1;
62
63 for (int i = beginPos; i < limit; i++) {
64 byte b = in.get(i);
65 if (b == CR) {
66 lastIsCR = true;
67 } else {
68 if (b == LF && lastIsCR) {
69 terminatorPos = i;
70 break;
71 }
72 lastIsCR = false;
73 }
74 }
75
76 if (terminatorPos >= 0) {
77 IoBuffer product;
78
79 int endPos = terminatorPos - 1;
80
81 if (beginPos < endPos) {
82 in.limit(endPos);
83
84 if (buffer == null) {
85 product = in.slice();
86 } else {
87 buffer.put(in);
88 product = buffer.flip();
89 buffer = null;
90 }
91
92 in.limit(limit);
93 } else {
94 // When input contained only CR or LF rather than actual data...
95 if (buffer == null) {
96 product = IoBuffer.allocate(0);
97 } else {
98 product = buffer.flip();
99 buffer = null;
100 }
101 }
102 in.position(terminatorPos + 1);
103 return finishDecode(product, out);
104 }
105
106 in.position(beginPos);
107
108 if (buffer == null) {
109 buffer = IoBuffer.allocate(in.remaining());
110 buffer.setAutoExpand(true);
111 }
112
113 buffer.put(in);
114
115 if (lastIsCR) {
116 buffer.position(buffer.position() - 1);
117 }
118
119 return this;
120 }
121
122 /**
123 * {@inheritDoc}
124 */
125 @Override
126 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
127 IoBuffer product;
128 // When input contained only CR or LF rather than actual data...
129 if (buffer == null) {
130 product = IoBuffer.allocate(0);
131 } else {
132 product = buffer.flip();
133 buffer = null;
134 }
135 return finishDecode(product, out);
136 }
137
138 /**
139 * Invoked when this state has reached a <code>CRLF</code>.
140 *
141 * @param product the read bytes including the <code>CRLF</code>.
142 * @param out the current {@link ProtocolDecoderOutput} used to write
143 * decoded messages.
144 * @return the next state if a state transition was triggered (use
145 * <code>this</code> for loop transitions) or <code>null</code> if
146 * the state machine has reached its end.
147 * @throws Exception if the read data violated protocol specification.
148 */
149 protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception;
150 }