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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.textline;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import org.apache.mina.core.buffer.BufferDataException;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.AttributeKey;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolDecoderException;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
import org.apache.mina.filter.codec.RecoverableProtocolDecoderException;
/**
* A {@link ProtocolDecoder} which decodes a text line into a string.
*
* @author Apache MINA Project
*/
public class TextLineDecoder implements ProtocolDecoder {
private static final AttributeKey CONTEXT = new AttributeKey(TextLineDecoder.class, "context");
private final Charset charset;
/** The delimiter used to determinate when a line has been fully decoded */
private final LineDelimiter delimiter;
/** An IoBuffer containing the delimiter */
private IoBuffer delimBuf;
/** The default maximum Line length. Default to 1024. */
private int maxLineLength = 1024;
/** The default maximum buffer length. Default to 128 chars. */
private int bufferLength = 128;
/**
* Creates a new instance with the current default {@link Charset}
* and {@link LineDelimiter#AUTO} delimiter.
*/
public TextLineDecoder() {
this(LineDelimiter.AUTO);
}
/**
* Creates a new instance with the current default {@link Charset}
* and the specified delimiter.
*
* @param delimiter The line delimiter to use
*/
public TextLineDecoder(String delimiter) {
this(new LineDelimiter(delimiter));
}
/**
* Creates a new instance with the current default {@link Charset}
* and the specified delimiter.
*
* @param delimiter The line delimiter to use
*/
public TextLineDecoder(LineDelimiter delimiter) {
this(Charset.defaultCharset(), delimiter);
}
/**
* Creates a new instance with the spcified charset
* and {@link LineDelimiter#AUTO} delimiter.
*
* @param charset The {@link Charset} to use
*/
public TextLineDecoder(Charset charset) {
this(charset, LineDelimiter.AUTO);
}
/**
* Creates a new instance with the spcified charset
* and the specified delimiter.
*
* @param charset The {@link Charset} to use
* @param delimiter The line delimiter to use
*/
public TextLineDecoder(Charset charset, String delimiter) {
this(charset, new LineDelimiter(delimiter));
}
/**
* Creates a new instance with the specified charset
* and the specified delimiter.
*
* @param charset The {@link Charset} to use
* @param delimiter The line delimiter to use
*/
public TextLineDecoder(Charset charset, LineDelimiter delimiter) {
if (charset == null) {
throw new IllegalArgumentException("charset parameter shuld not be null");
}
if (delimiter == null) {
throw new IllegalArgumentException("delimiter parameter should not be null");
}
this.charset = charset;
this.delimiter = delimiter;
// Convert delimiter to ByteBuffer if not done yet.
if (delimBuf == null) {
IoBuffer tmp = IoBuffer.allocate(2).setAutoExpand(true);
try {
tmp.putString(delimiter.getValue(), charset.newEncoder());
} catch (CharacterCodingException cce) {
}
tmp.flip();
delimBuf = tmp;
}
}
/**
* @return the allowed maximum size of the line to be decoded.
* If the size of the line to be decoded exceeds this value, the
* decoder will throw a {@link BufferDataException}. The default
* value is 1024 (1KB).
*/
public int getMaxLineLength() {
return maxLineLength;
}
/**
* Sets the allowed maximum size of the line to be decoded.
* If the size of the line to be decoded exceeds this value, the
* decoder will throw a {@link BufferDataException}. The default
* value is 1024 (1KB).
*
* @param maxLineLength The maximum line length
*/
public void setMaxLineLength(int maxLineLength) {
if (maxLineLength <= 0) {
throw new IllegalArgumentException("maxLineLength (" + maxLineLength + ") should be a positive value");
}
this.maxLineLength = maxLineLength;
}
/**
* Sets the default buffer size. This buffer is used in the Context
* to store the decoded line.
*
* @param bufferLength The default bufer size
*/
public void setBufferLength(int bufferLength) {
if (bufferLength <= 0) {
throw new IllegalArgumentException("bufferLength (" + maxLineLength + ") should be a positive value");
}
this.bufferLength = bufferLength;
}
/**
* @return the allowed buffer size used to store the decoded line
* in the Context instance.
*/
public int getBufferLength() {
return bufferLength;
}
/**
* {@inheritDoc}
*/
@Override
public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
Context ctx = getContext(session);
if (LineDelimiter.AUTO.equals(delimiter)) {
decodeAuto(ctx, session, in, out);
} else {
decodeNormal(ctx, session, in, out);
}
}
/**
* @return the context for this session
*
* @param session The session for which we want the context
*/
private Context getContext(IoSession session) {
Context ctx;
ctx = (Context) session.getAttribute(CONTEXT);
if (ctx == null) {
ctx = new Context(bufferLength);
session.setAttribute(CONTEXT, ctx);
}
return ctx;
}
/**
* {@inheritDoc}
*/
@Override
public void finishDecode(IoSession session, ProtocolDecoderOutput out) throws Exception {
// Do nothing
}
/**
* {@inheritDoc}
*/
@Override
public void dispose(IoSession session) throws Exception {
Context ctx = (Context) session.getAttribute(CONTEXT);
if (ctx != null) {
session.removeAttribute(CONTEXT);
}
}
/**
* Decode a line using the default delimiter on the current system
*/
private void decodeAuto(Context ctx, IoSession session, IoBuffer in, ProtocolDecoderOutput out)
throws CharacterCodingException, ProtocolDecoderException {
int matchCount = ctx.getMatchCount();
// Try to find a match
int oldPos = in.position();
int oldLimit = in.limit();
while (in.hasRemaining()) {
byte b = in.get();
boolean matched = false;
switch (b) {
case '\r':
// Might be Mac, but we don't auto-detect Mac EOL
// to avoid confusion.
matchCount++;
break;
case '\n':
// UNIX
matchCount++;
matched = true;
break;
default:
matchCount = 0;
}
if (matched) {
// Found a match.
int pos = in.position();
in.limit(pos);
in.position(oldPos);
ctx.append(in);
in.limit(oldLimit);
in.position(pos);
if (ctx.getOverflowPosition() == 0) {
IoBuffer buf = ctx.getBuffer();
buf.flip();
buf.limit(buf.limit() - matchCount);
try {
byte[] data = new byte[buf.limit()];
buf.get(data);
CharsetDecoder decoder = ctx.getDecoder();
CharBuffer buffer = decoder.decode(ByteBuffer.wrap(data));
String str = buffer.toString();
writeText(session, str, out);
} finally {
buf.clear();
}
} else {
int overflowPosition = ctx.getOverflowPosition();
ctx.reset();
throw new RecoverableProtocolDecoderException("Line is too long: " + overflowPosition);
}
oldPos = pos;
matchCount = 0;
}
}
// Put remainder to buf.
in.position(oldPos);
ctx.append(in);
ctx.setMatchCount(matchCount);
}
/**
* Decode a line using the delimiter defined by the caller
*/
private void decodeNormal(Context ctx, IoSession session, IoBuffer in, ProtocolDecoderOutput out)
throws CharacterCodingException, ProtocolDecoderException {
int matchCount = ctx.getMatchCount();
// Try to find a match
int oldPos = in.position();
int oldLimit = in.limit();
while (in.hasRemaining()) {
byte b = in.get();
if (delimBuf.get(matchCount) == b) {
matchCount++;
if (matchCount == delimBuf.limit()) {
// Found a match.
int pos = in.position();
in.limit(pos);
in.position(oldPos);
ctx.append(in);
in.limit(oldLimit);
in.position(pos);
if (ctx.getOverflowPosition() == 0) {
IoBuffer buf = ctx.getBuffer();
buf.flip();
buf.limit(buf.limit() - matchCount);
try {
writeText(session, buf.getString(ctx.getDecoder()), out);
} finally {
buf.clear();
}
} else {
int overflowPosition = ctx.getOverflowPosition();
ctx.reset();
throw new RecoverableProtocolDecoderException("Line is too long: " + overflowPosition);
}
oldPos = pos;
matchCount = 0;
}
} else {
// fix for DIRMINA-506 & DIRMINA-536
in.position(Math.max(0, in.position() - matchCount));
matchCount = 0;
}
}
// Put remainder to buf.
in.position(oldPos);
ctx.append(in);
ctx.setMatchCount(matchCount);
}
/**
* By default, this method propagates the decoded line of text to
* {@code ProtocolDecoderOutput#write(Object)}. You may override this method to modify
* the default behavior.
*
* @param session the {@code IoSession} the received data.
* @param text the decoded text
* @param out the upstream {@code ProtocolDecoderOutput}.
*/
protected void writeText(IoSession session, String text, ProtocolDecoderOutput out) {
out.write(text);
}
/**
* A Context used during the decoding of a lin. It stores the decoder,
* the temporary buffer containing the decoded line, and other status flags.
*
* @author Apache Directory Project
* @version $Rev$, $Date$
*/
private class Context {
/** The decoder */
private final CharsetDecoder decoder;
/** The temporary buffer containing the decoded line */
private final IoBuffer buf;
/** The number of lines found so far */
private int matchCount = 0;
/** A counter to signal that the line is too long */
private int overflowPosition = 0;
/** Create a new Context object with a default buffer */
private Context(int bufferLength) {
decoder = charset.newDecoder();
buf = IoBuffer.allocate(bufferLength).setAutoExpand(true);
}
public CharsetDecoder getDecoder() {
return decoder;
}
public IoBuffer getBuffer() {
return buf;
}
public int getOverflowPosition() {
return overflowPosition;
}
public int getMatchCount() {
return matchCount;
}
public void setMatchCount(int matchCount) {
this.matchCount = matchCount;
}
public void reset() {
overflowPosition = 0;
matchCount = 0;
decoder.reset();
}
public void append(IoBuffer in) {
if (overflowPosition != 0) {
discard(in);
} else if (buf.position() > maxLineLength - in.remaining()) {
overflowPosition = buf.position();
buf.clear();
discard(in);
} else {
getBuffer().put(in);
}
}
private void discard(IoBuffer in) {
if (Integer.MAX_VALUE - in.remaining() < overflowPosition) {
overflowPosition = Integer.MAX_VALUE;
} else {
overflowPosition += in.remaining();
}
in.position(in.limit());
}
}
}