io.netty.handler.codec

Class LineBasedFrameDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.LineBasedFrameDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

Direct Known Subclasses:

SmtpResponseDecoder

public class LineBasedFrameDecoder
extends ByteToMessageDecoder

A decoder that splits the received ByteBufs on line endings.

Both "\n" and "\r\n" are handled.

The byte stream is expected to be in UTF-8 character encoding or ASCII. The current implementation uses direct byte to char cast and then compares that char to a few low range ASCII characters like '\n' or '\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 DelimiterBasedFrameDecoder.

Users should be aware that used as is, the lenient approach on lone '\n might result on a parser diffenrencial on line based protocols requiring the use of "\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.

Nested Class Summary

Nested classes/interfaces inherited from class io.netty.handler.codec.ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields inherited from class io.netty.handler.codec.ByteToMessageDecoder

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Constructor Summary

Constructors

Constructor and Description
LineBasedFrameDecoder(int maxLength) Creates a new decoder.
LineBasedFrameDecoder(int maxLength, boolean stripDelimiter, boolean failFast) Creates a new decoder.

Method Summary

Modifier and Type	Method and Description
protected Object	decode(ChannelHandlerContext ctx, ByteBuf buffer) Create a frame out of the ByteBuf and return it.
protected void	decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) Decode the from one ByteBuf to an other.

Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder

actualReadableBytes, callDecode, channelInactive, channelRead, channelReadComplete, decodeLast, discardSomeReadBytes, handlerRemoved, handlerRemoved0, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode, userEventTriggered

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.channel.ChannelHandler

handlerAdded

Constructor Detail

LineBasedFrameDecoder

public LineBasedFrameDecoder(int maxLength)

Creates a new decoder.

Parameters:

maxLength - the maximum length of the decoded frame. A TooLongFrameException is thrown if the length of the frame exceeds this value.

LineBasedFrameDecoder

public LineBasedFrameDecoder(int maxLength,
                             boolean stripDelimiter,
                             boolean failFast)

Creates a new decoder.

Parameters:

maxLength - the maximum length of the decoded frame. A TooLongFrameException is thrown if the length of the frame exceeds this value.

stripDelimiter - whether the decoded frame should strip out the delimiter or not

failFast - If true, a 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 TooLongFrameException is thrown after the entire frame that exceeds maxFrameLength has been read.

Method Detail

decode

protected final void decode(ChannelHandlerContext ctx,
                            ByteBuf in,
                            List<Object> out)
                     throws Exception

Description copied from class: ByteToMessageDecoder

Decode the from one ByteBuf to an other. This method will be called till either the input ByteBuf has nothing to read when return from this method or till nothing was read from the input ByteBuf.

Specified by:

decode in class ByteToMessageDecoder

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

out - the List to which decoded messages should be added

Throws:

Exception - is thrown if an error occurs

decode

protected Object decode(ChannelHandlerContext ctx,
                        ByteBuf buffer)
                 throws Exception

Create a frame out of the ByteBuf and return it.

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

buffer - the ByteBuf from which to read data

Returns:

frame the ByteBuf which represent the frame or null if no frame could be created.

Throws:

Exception