org.apache.mina.filter.codec.statemachine.CrLfDecodingState Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.mina.filter.codec.statemachine;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.filter.codec.ProtocolDecoderException;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
/**
* {@link DecodingState} which decodes a single CRLF.
* If it is found, the bytes are consumed and true
* is provided as the product. Otherwise, read bytes are pushed back
* to the stream, and false is provided as the
* product.
* Note that if we find a CR but do not find a following LF, we raise
* an error.
*
* @author Apache MINA Project
*/
public abstract class CrLfDecodingState implements DecodingState {
/**
* Carriage return character
*/
private static final byte CR = 13;
/**
* Line feed character
*/
private static final byte LF = 10;
private boolean hasCR;
/**
* {@inheritDoc}
*/
@Override
public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
boolean found = false;
boolean finished = false;
while (in.hasRemaining()) {
byte b = in.get();
if (!hasCR) {
if (b == CR) {
hasCR = true;
} else {
if (b == LF) {
found = true;
} else {
in.position(in.position() - 1);
found = false;
}
finished = true;
break;
}
} else {
if (b == LF) {
found = true;
finished = true;
break;
}
throw new ProtocolDecoderException("Expected LF after CR but was: " + (b & 0xff));
}
}
if (finished) {
hasCR = false;
return finishDecode(found, out);
}
return this;
}
/**
* {@inheritDoc}
*/
@Override
public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
return finishDecode(false, out);
}
/**
* Invoked when this state has found a CRLF.
*
* @param foundCRLF true if CRLF was found.
* @param out the current {@link ProtocolDecoderOutput} used to write
* decoded messages.
* @return the next state if a state transition was triggered (use
* this for loop transitions) or null if
* the state machine has reached its end.
* @throws Exception if the read data violated protocol specification.
*/
protected abstract DecodingState finishDecode(boolean foundCRLF, ProtocolDecoderOutput out) throws Exception;
}