io.netty.handler.codec.http

Class HttpResponseDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.http.HttpObjectDecoder

io.netty.handler.codec.http.HttpResponseDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

public class HttpResponseDecoder
extends HttpObjectDecoder

Decodes ByteBufs into HttpResponses and HttpContents.

Parameters that prevents excessive memory consumption

Name	Meaning
maxInitialLineLength	The maximum length of the initial line (e.g. "HTTP/1.0 200 OK") If the length of the initial line exceeds this value, a TooLongHttpLineException will be raised.
maxHeaderSize	The maximum length of all headers. If the sum of the length of each header exceeds this value, a TooLongHttpHeaderException will be raised.
maxChunkSize	The maximum length of the content or each chunk. If the content length exceeds this value, the transfer encoding of the decoded response will be converted to 'chunked' and the content will be split into multiple HttpContents. If the transfer encoding of the HTTP response is 'chunked' already, each chunk will be split into smaller chunks if the length of the chunk exceeds this value. If you prefer not to handle HttpContents in your handler, insert HttpObjectAggregator after this decoder in the ChannelPipeline.

Parameters that control parsing behavior

Name	Default value	Meaning
allowDuplicateContentLengths		When set to false, will reject any messages that contain multiple Content-Length header fields. When set to true, will allow multiple Content-Length headers only if they are all the same decimal value. The duplicated field-values will be replaced with a single valid Content-Length field. See RFC 7230, Section 3.3.2.
allowPartialChunks		If the length of a chunk exceeds the ByteBufs readable bytes and allowPartialChunks is set to true, the chunk will be split into multiple HttpContents. Otherwise, if the chunk size does not exceed maxChunkSize and allowPartialChunks is set to false, the ByteBuf is not decoded into an HttpContent until the readable bytes are greater or equal to the chunk size.

Decoding a response for a HEAD request

Unlike other HTTP requests, the successful response of a HEAD request does not have any content even if there is Content-Length header. Because HttpResponseDecoder is not able to determine if the response currently being decoded is associated with a HEAD request, you must override HttpObjectDecoder.isContentAlwaysEmpty(HttpMessage) to return true for the response of the HEAD request.

If you are writing an HTTP client that issues a HEAD request, please use HttpClientCodec instead of this decoder. It will perform additional state management to handle the responses for HEAD requests correctly.

Decoding a response for a CONNECT request

You also need to do additional state management to handle the response of a CONNECT request properly, like you did for HEAD. One difference is that the decoder should stop decoding completely after decoding the successful 200 response since the connection is not an HTTP connection anymore.

HttpClientCodec also handles this edge case correctly, so you have to use HttpClientCodec if you are writing an HTTP client that issues a CONNECT request.

Header Validation

It is recommended to always enable header validation.

Without header validation, your system can become vulnerable to CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') .

This recommendation stands even when both peers in the HTTP exchange are trusted, as it helps with defence-in-depth.

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.http.HttpObjectDecoder

DEFAULT_ALLOW_DUPLICATE_CONTENT_LENGTHS, DEFAULT_ALLOW_PARTIAL_CHUNKS, DEFAULT_CHUNKED_SUPPORTED, DEFAULT_INITIAL_BUFFER_SIZE, DEFAULT_MAX_CHUNK_SIZE, DEFAULT_MAX_HEADER_SIZE, DEFAULT_MAX_INITIAL_LINE_LENGTH, DEFAULT_VALIDATE_HEADERS, headersFactory, trailersFactory, validateHeaders

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

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Constructor Summary

Constructors

Constructor and Description
HttpResponseDecoder() Creates a new instance with the default maxInitialLineLength (4096), maxHeaderSize (8192), and maxChunkSize (8192).
HttpResponseDecoder(HttpDecoderConfig config) Creates a new instance with the specified configuration.
HttpResponseDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) Creates a new instance with the specified parameters.
HttpResponseDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders) Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.
HttpResponseDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders, int initialBufferSize) Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.
HttpResponseDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders, int initialBufferSize, boolean allowDuplicateContentLengths) Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.
HttpResponseDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders, int initialBufferSize, boolean allowDuplicateContentLengths, boolean allowPartialChunks) Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.

Method Summary

Modifier and Type	Method and Description
protected HttpMessage	createInvalidMessage()
protected HttpMessage	createMessage(String[] initialLine)
protected boolean	isDecodingRequest()

Methods inherited from class io.netty.handler.codec.http.HttpObjectDecoder

decode, decodeLast, handlerRemoved0, handleTransferEncodingChunkedWithContentLength, isContentAlwaysEmpty, isSwitchingToNonHttp1Protocol, isValidating, reset, splitFirstWordInitialLine, splitHeaderName, splitSecondWordInitialLine, splitThirdWordInitialLine, userEventTriggered

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

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

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

HttpResponseDecoder

public HttpResponseDecoder()

Creates a new instance with the default maxInitialLineLength (4096), maxHeaderSize (8192), and maxChunkSize (8192).

HttpResponseDecoder

public HttpResponseDecoder(int maxInitialLineLength,
                           int maxHeaderSize,
                           int maxChunkSize)

Creates a new instance with the specified parameters.

HttpResponseDecoder

@Deprecated
public HttpResponseDecoder(int maxInitialLineLength,
                                       int maxHeaderSize,
                                       int maxChunkSize,
                                       boolean validateHeaders)

Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.

HttpResponseDecoder

@Deprecated
public HttpResponseDecoder(int maxInitialLineLength,
                                       int maxHeaderSize,
                                       int maxChunkSize,
                                       boolean validateHeaders,
                                       int initialBufferSize)

Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.

HttpResponseDecoder

@Deprecated
public HttpResponseDecoder(int maxInitialLineLength,
                                       int maxHeaderSize,
                                       int maxChunkSize,
                                       boolean validateHeaders,
                                       int initialBufferSize,
                                       boolean allowDuplicateContentLengths)

Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.

HttpResponseDecoder

@Deprecated
public HttpResponseDecoder(int maxInitialLineLength,
                                       int maxHeaderSize,
                                       int maxChunkSize,
                                       boolean validateHeaders,
                                       int initialBufferSize,
                                       boolean allowDuplicateContentLengths,
                                       boolean allowPartialChunks)

Deprecated. Prefer the HttpResponseDecoder(HttpDecoderConfig) constructor.

HttpResponseDecoder

public HttpResponseDecoder(HttpDecoderConfig config)

Creates a new instance with the specified configuration.

Method Detail

createMessage

protected HttpMessage createMessage(String[] initialLine)

Specified by:

createMessage in class HttpObjectDecoder

createInvalidMessage

protected HttpMessage createInvalidMessage()

Specified by:

createInvalidMessage in class HttpObjectDecoder

isDecodingRequest

protected boolean isDecodingRequest()

Specified by:

isDecodingRequest in class HttpObjectDecoder