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.common.IoBuffer;
23 import org.apache.mina.filter.codec.ProtocolDecoderException;
24 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
25
26 /**
27 * Decodes a single <code>CRLF</code>.
28 * If it is found, the bytes are consumed and <code>Boolean.TRUE</code>
29 * is provided as the product. Otherwise, read bytes are pushed back
30 * to the stream, and <code>Boolean.FALSE</code> is provided as the
31 * product.
32 * Note that if we find a CR but do not find a following LF, we raise
33 * an error.
34 *
35 * @author The Apache MINA Project (dev@mina.apache.org)
36 * @version $Rev: 601994 $, $Date: 2007-12-06 21:58:00 -0700 (Thu, 06 Dec 2007) $
37 */
38 public abstract class CrLfDecodingState implements DecodingState {
39 /**
40 * Carriage return character
41 */
42 private static final byte CR = 13;
43
44 /**
45 * Line feed character
46 */
47 private static final byte LF = 10;
48
49 private boolean hasCR;
50
51 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
52 throws Exception {
53 boolean found = false;
54 boolean finished = false;
55 while (in.hasRemaining()) {
56 byte b = in.get();
57 if (!hasCR) {
58 if (b == CR) {
59 hasCR = true;
60 } else {
61 if (b == LF) {
62 found = true;
63 } else {
64 in.position(in.position() - 1);
65 found = false;
66 }
67 finished = true;
68 break;
69 }
70 } else {
71 if (b == LF) {
72 found = true;
73 finished = true;
74 break;
75 } else {
76 throw new ProtocolDecoderException(
77 "Expected LF after CR but was: " + (b & 0xff));
78 }
79 }
80 }
81
82 if (finished) {
83 hasCR = false;
84 return finishDecode(found, out);
85 } else {
86 return this;
87 }
88 }
89
90 public DecodingState finishDecode(ProtocolDecoderOutput out)
91 throws Exception {
92 return finishDecode(false, out);
93 }
94
95 protected abstract DecodingState finishDecode(boolean foundCRLF,
96 ProtocolDecoderOutput out) throws Exception;
97 }