001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.mina.filter.codec.statemachine; 021 022import org.apache.mina.core.buffer.IoBuffer; 023import org.apache.mina.filter.codec.ProtocolDecoderException; 024import org.apache.mina.filter.codec.ProtocolDecoderOutput; 025 026/** 027 * {@link DecodingState} which decodes a single <code>CRLF</code>. 028 * If it is found, the bytes are consumed and <tt>true</tt> 029 * is provided as the product. Otherwise, read bytes are pushed back 030 * to the stream, and <tt>false</tt> is provided as the 031 * product. 032 * Note that if we find a CR but do not find a following LF, we raise 033 * an error. 034 * 035 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 036 */ 037public abstract class CrLfDecodingState implements DecodingState { 038 /** 039 * Carriage return character 040 */ 041 private static final byte CR = 13; 042 043 /** 044 * Line feed character 045 */ 046 private static final byte LF = 10; 047 048 private boolean hasCR; 049 050 /** 051 * {@inheritDoc} 052 */ 053 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception { 054 boolean found = false; 055 boolean finished = false; 056 while (in.hasRemaining()) { 057 byte b = in.get(); 058 if (!hasCR) { 059 if (b == CR) { 060 hasCR = true; 061 } else { 062 if (b == LF) { 063 found = true; 064 } else { 065 in.position(in.position() - 1); 066 found = false; 067 } 068 finished = true; 069 break; 070 } 071 } else { 072 if (b == LF) { 073 found = true; 074 finished = true; 075 break; 076 } 077 078 throw new ProtocolDecoderException("Expected LF after CR but was: " + (b & 0xff)); 079 } 080 } 081 082 if (finished) { 083 hasCR = false; 084 return finishDecode(found, out); 085 } 086 087 return this; 088 } 089 090 /** 091 * {@inheritDoc} 092 */ 093 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception { 094 return finishDecode(false, out); 095 } 096 097 /** 098 * Invoked when this state has found a <code>CRLF</code>. 099 * 100 * @param foundCRLF <tt>true</tt> if <code>CRLF</code> was found. 101 * @param out the current {@link ProtocolDecoderOutput} used to write 102 * decoded messages. 103 * @return the next state if a state transition was triggered (use 104 * <code>this</code> for loop transitions) or <code>null</code> if 105 * the state machine has reached its end. 106 * @throws Exception if the read data violated protocol specification. 107 */ 108 protected abstract DecodingState finishDecode(boolean foundCRLF, ProtocolDecoderOutput out) throws Exception; 109}