io.netty.handler.codec.LineBasedFrameDecoder Maven / Gradle / Ivy
/*
* Copyright 2012 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.handler.codec;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ByteProcessor;
import java.util.List;
/**
* A decoder that splits the received {@link ByteBuf}s on line endings.
*
* Both {@code "\n"} and {@code "\r\n"} are handled.
*
* The byte stream is expected to be in UTF-8 character encoding or ASCII. The current implementation
* uses direct {@code byte} to {@code char} cast and then compares that {@code char} to a few low range
* ASCII characters like {@code '\n'} or {@code '\r'}. UTF-8 is not using low range [0..0x7F]
* byte values for multibyte codepoint representations therefore fully supported by this implementation.
*
* For a more general delimiter-based decoder, see {@link DelimiterBasedFrameDecoder}.
*
* Users should be aware that used as is, the lenient approach on lone {@code '\n} might result on a parser
* diffenrencial on line based protocols requiring the use of {@code "\r\n"} delimiters like SMTP and can
* result in attacks similar to
* SMTP smuggling.
* Validating afterward the end of line pattern can be a possible mitigation.
*/
public class LineBasedFrameDecoder extends ByteToMessageDecoder {
/** Maximum length of a frame we're willing to decode. */
private final int maxLength;
/** Whether or not to throw an exception as soon as we exceed maxLength. */
private final boolean failFast;
private final boolean stripDelimiter;
/** True if we're discarding input because we're already over maxLength. */
private boolean discarding;
private int discardedBytes;
/** Last scan position. */
private int offset;
/**
* Creates a new decoder.
* @param maxLength the maximum length of the decoded frame.
* A {@link TooLongFrameException} is thrown if
* the length of the frame exceeds this value.
*/
public LineBasedFrameDecoder(final int maxLength) {
this(maxLength, true, false);
}
/**
* Creates a new decoder.
* @param maxLength the maximum length of the decoded frame.
* A {@link TooLongFrameException} is thrown if
* the length of the frame exceeds this value.
* @param stripDelimiter whether the decoded frame should strip out the
* delimiter or not
* @param failFast If true, a {@link TooLongFrameException} is
* thrown as soon as the decoder notices the length of the
* frame will exceed maxFrameLength regardless of
* whether the entire frame has been read.
* If false, a {@link TooLongFrameException} is
* thrown after the entire frame that exceeds
* maxFrameLength has been read.
*/
public LineBasedFrameDecoder(final int maxLength, final boolean stripDelimiter, final boolean failFast) {
this.maxLength = maxLength;
this.failFast = failFast;
this.stripDelimiter = stripDelimiter;
}
@Override
protected final void decode(ChannelHandlerContext ctx, ByteBuf in, List