Class LineBasedFrameDecoder
- All Implemented Interfaces:
ChannelHandler
,ChannelInboundHandler
- Direct Known Subclasses:
SmtpResponseDecoder
ByteBuf
s 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.
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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
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate int
private boolean
True if we're discarding input because we're already over maxLength.private final boolean
Whether or not to throw an exception as soon as we exceed maxLength.private final int
Maximum length of a frame we're willing to decode.private int
Last scan position.private final boolean
Fields inherited from class io.netty.handler.codec.ByteToMessageDecoder
COMPOSITE_CUMULATOR, cumulation, MERGE_CUMULATOR
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Constructor Summary
ConstructorsConstructorDescriptionLineBasedFrameDecoder
(int maxLength) Creates a new decoder.LineBasedFrameDecoder
(int maxLength, boolean stripDelimiter, boolean failFast) Creates a new decoder. -
Method Summary
Modifier and TypeMethodDescriptionprotected Object
decode
(ChannelHandlerContext ctx, ByteBuf buffer) Create a frame out of theByteBuf
and return it.protected final void
decode
(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) Decode the from oneByteBuf
to an other.private void
fail
(ChannelHandlerContext ctx, int length) private void
fail
(ChannelHandlerContext ctx, String length) private int
findEndOfLine
(ByteBuf buffer) Returns the index in the buffer of the end of line found.Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder
actualReadableBytes, callDecode, channelInactive, channelInputClosed, channelRead, channelReadComplete, decodeLast, decodeRemovalReentryProtection, discardSomeReadBytes, expandCumulation, fireChannelRead, fireChannelRead, 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
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Field Details
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maxLength
private final int maxLengthMaximum length of a frame we're willing to decode. -
failFast
private final boolean failFastWhether or not to throw an exception as soon as we exceed maxLength. -
stripDelimiter
private final boolean stripDelimiter -
discarding
private boolean discardingTrue if we're discarding input because we're already over maxLength. -
discardedBytes
private int discardedBytes -
offset
private int offsetLast scan position.
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Constructor Details
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LineBasedFrameDecoder
public LineBasedFrameDecoder(int maxLength) Creates a new decoder.- Parameters:
maxLength
- the maximum length of the decoded frame. ATooLongFrameException
is thrown if the length of the frame exceeds this value.
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LineBasedFrameDecoder
public LineBasedFrameDecoder(int maxLength, boolean stripDelimiter, boolean failFast) Creates a new decoder.- Parameters:
maxLength
- the maximum length of the decoded frame. ATooLongFrameException
is thrown if the length of the frame exceeds this value.stripDelimiter
- whether the decoded frame should strip out the delimiter or notfailFast
- If true, aTooLongFrameException
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, aTooLongFrameException
is thrown after the entire frame that exceeds maxFrameLength has been read.
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Method Details
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decode
protected final void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception Description copied from class:ByteToMessageDecoder
Decode the from oneByteBuf
to an other. This method will be called till either the inputByteBuf
has nothing to read when return from this method or till nothing was read from the inputByteBuf
.- Specified by:
decode
in classByteToMessageDecoder
- Parameters:
ctx
- theChannelHandlerContext
which thisByteToMessageDecoder
belongs toin
- theByteBuf
from which to read dataout
- theList
to which decoded messages should be added- Throws:
Exception
- is thrown if an error occurs
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decode
Create a frame out of theByteBuf
and return it.- Parameters:
ctx
- theChannelHandlerContext
which thisByteToMessageDecoder
belongs tobuffer
- theByteBuf
from which to read data- Returns:
- frame the
ByteBuf
which represent the frame ornull
if no frame could be created. - Throws:
Exception
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fail
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fail
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findEndOfLine
Returns the index in the buffer of the end of line found. Returns -1 if no end of line was found in the buffer.
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