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 }