HttpObjectDecoder (Netty API Reference (4.1.50.Final))

java.lang.Object
- io.netty.channel.ChannelHandlerAdapter
- - io.netty.channel.ChannelInboundHandlerAdapter
  - - io.netty.handler.codec.ByteToMessageDecoder
    - - io.netty.handler.codec.http.HttpObjectDecoder

All Implemented Interfaces:: ChannelHandler, ChannelInboundHandler

Direct Known Subclasses:: HttpRequestDecoder, HttpResponseDecoder, RtspDecoder, RtspObjectDecoder

public abstract class HttpObjectDecoder
extends ByteToMessageDecoder

Decodes ByteBufs into HttpMessages and HttpContents.

Parameters that prevents excessive memory consumption

Name	Meaning
`maxInitialLineLength`	The maximum length of the initial line (e.g. `"GET / HTTP/1.0"` or `"HTTP/1.0 200 OK"`) If the length of the initial line exceeds this value, a `TooLongFrameException` will be raised.
`maxHeaderSize`	The maximum length of all headers. If the sum of the length of each header exceeds this value, a `TooLongFrameException` will be raised.
`maxChunkSize`	The maximum length of the content or each chunk. If the content length (or the length of each chunk) exceeds this value, the content or chunk will be split into multiple `HttpContent`s whose length is `maxChunkSize` at maximum.

Chunked Content

If the content of an HTTP message is greater than maxChunkSize or the transfer encoding of the HTTP message is 'chunked', this decoder generates one HttpMessage instance and its following HttpContents per single HTTP message to avoid excessive memory consumption. For example, the following HTTP message:

 GET / HTTP/1.1
 Transfer-Encoding: chunked

 1a
 abcdefghijklmnopqrstuvwxyz
 10
 1234567890abcdef
 0
 Content-MD5: ...
 [blank line]

triggers HttpRequestDecoder to generate 3 objects:

An HttpRequest,
The first HttpContent whose content is 'abcdefghijklmnopqrstuvwxyz',
The second LastHttpContent whose content is '1234567890abcdef', which marks the end of the content.

If you prefer not to handle HttpContents by yourself for your convenience, insert HttpObjectAggregator after this decoder in the ChannelPipeline. However, please note that your server might not be as memory efficient as without the aggregator.

Extensibility

Please note that this decoder is designed to be extended to implement a protocol derived from HTTP, such as RTSP and ICAP. To implement the decoder of such a derived protocol, extend this class and implement all abstract methods properly.

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
Modifier and Type Field and Description

protected boolean validateHeaders
- Fields inherited from class io.netty.handler.codec.ByteToMessageDecoder
  COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Fields
Modifier and Type	Field and Description
`protected boolean`	`validateHeaders`

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`HttpObjectDecoder()` Creates a new instance with the default `maxInitialLineLength (4096`}, `maxHeaderSize (8192)`, and `maxChunkSize (8192)`.
`protected`	`HttpObjectDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean chunkedSupported)` Creates a new instance with the specified parameters.
`protected`	`HttpObjectDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean chunkedSupported, boolean validateHeaders)` Creates a new instance with the specified parameters.
`protected`	`HttpObjectDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean chunkedSupported, boolean validateHeaders, int initialBufferSize)`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected abstract HttpMessage`	`createInvalidMessage()`
`protected abstract HttpMessage`	`createMessage(java.lang.String[] initialLine)`
`protected void`	`decode(ChannelHandlerContext ctx, ByteBuf buffer, java.util.List<java.lang.Object> out)` Decode the from one `ByteBuf` to an other.
`protected void`	`decodeLast(ChannelHandlerContext ctx, ByteBuf in, java.util.List<java.lang.Object> out)` Is called one last time when the `ChannelHandlerContext` goes in-active.
`protected void`	`handleTransferEncodingChunkedWithContentLength(HttpMessage message)` Invoked when a message with both a "Transfer-Encoding: chunked" and a "Content-Length" header field is detected.
`protected boolean`	`isContentAlwaysEmpty(HttpMessage msg)`
`protected abstract boolean`	`isDecodingRequest()`
`protected boolean`	`isSwitchingToNonHttp1Protocol(HttpResponse msg)` Returns true if the server switched to a different protocol than HTTP/1.0 or HTTP/1.1, e.g.
`void`	`reset()` Resets the state of the decoder so that it is ready to decode a new message.
`void`	`userEventTriggered(ChannelHandlerContext ctx, java.lang.Object evt)` Calls `ChannelHandlerContext.fireUserEventTriggered(Object)` to forward to the next `ChannelInboundHandler` in the `ChannelPipeline`.

Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder
actualReadableBytes, callDecode, channelInactive, channelRead, channelReadComplete, discardSomeReadBytes, handlerRemoved, handlerRemoved0, 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

- Field Detail
  - validateHeaders
```
protected final boolean validateHeaders
```
- Constructor Detail
  - HttpObjectDecoder
```
protected HttpObjectDecoder()
```
    Creates a new instance with the default maxInitialLineLength (4096}, maxHeaderSize (8192), and maxChunkSize (8192).
  - HttpObjectDecoder
```
protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported)
```
    Creates a new instance with the specified parameters.
  - HttpObjectDecoder
```
protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders)
```
    Creates a new instance with the specified parameters.
  - HttpObjectDecoder
```
protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders,
                            int initialBufferSize)
```
- Method Detail
  - decode
```
protected void decode(ChannelHandlerContext ctx,
                      ByteBuf buffer,
                      java.util.List<java.lang.Object> out)
               throws java.lang.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
    
    buffer - the ByteBuf from which to read data
    
    out - the List to which decoded messages should be added
    
    Throws:
    
    java.lang.Exception - is thrown if an error occurs
  - decodeLast
```
protected void decodeLast(ChannelHandlerContext ctx,
                          ByteBuf in,
                          java.util.List<java.lang.Object> out)
                   throws java.lang.Exception
```
    Description copied from class: ByteToMessageDecoder
    
    Is called one last time when the ChannelHandlerContext goes in-active. Which means the ByteToMessageDecoder.channelInactive(ChannelHandlerContext) was triggered. By default this will just call ByteToMessageDecoder.decode(ChannelHandlerContext, ByteBuf, List) but sub-classes may override this for some special cleanup operation.
    
    Overrides:
    
    decodeLast in class ByteToMessageDecoder
    
    Throws:
    
    java.lang.Exception
  - userEventTriggered
```
public void userEventTriggered(ChannelHandlerContext ctx,
                               java.lang.Object evt)
                        throws java.lang.Exception
```
    Description copied from class: ChannelInboundHandlerAdapter
    
    Calls ChannelHandlerContext.fireUserEventTriggered(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.
    
    Specified by:
    
    userEventTriggered in interface ChannelInboundHandler
    
    Overrides:
    
    userEventTriggered in class ByteToMessageDecoder
    
    Throws:
    
    java.lang.Exception
  - isContentAlwaysEmpty
```
protected boolean isContentAlwaysEmpty(HttpMessage msg)
```
  - isSwitchingToNonHttp1Protocol
```
protected boolean isSwitchingToNonHttp1Protocol(HttpResponse msg)
```
    Returns true if the server switched to a different protocol than HTTP/1.0 or HTTP/1.1, e.g. HTTP/2 or Websocket. Returns false if the upgrade happened in a different layer, e.g. upgrade from HTTP/1.1 to HTTP/1.1 over TLS.
  - reset
```
public void reset()
```
    Resets the state of the decoder so that it is ready to decode a new message. This method is useful for handling a rejected request with Expect: 100-continue header.
  - handleTransferEncodingChunkedWithContentLength
```
protected void handleTransferEncodingChunkedWithContentLength(HttpMessage message)
```
    Invoked when a message with both a "Transfer-Encoding: chunked" and a "Content-Length" header field is detected. The default behavior is to remove the Content-Length field, but this method could be overridden to change the behavior (to, e.g., throw an exception and produce an invalid message).
    See: https://tools.ietf.org/html/rfc7230#section-3.3.3
```
     If a message is received with both a Transfer-Encoding and a
     Content-Length header field, the Transfer-Encoding overrides the
     Content-Length.  Such a message might indicate an attempt to
     perform request smuggling (Section 9.5) or response splitting
     (Section 9.4) and ought to be handled as an error.  A sender MUST
     remove the received Content-Length field prior to forwarding such
     a message downstream.
 
```
    Also see: https://github.com/apache/tomcat/blob/b693d7c1981fa7f51e58bc8c8e72e3fe80b7b773/ java/org/apache/coyote/http11/Http11Processor.java#L747-L755 https://github.com/nginx/nginx/blob/0ad4393e30c119d250415cb769e3d8bc8dce5186/ src/http/ngx_http_request.c#L1946-L1953
  - isDecodingRequest
```
protected abstract boolean isDecodingRequest()
```
  - createMessage
```
protected abstract HttpMessage createMessage(java.lang.String[] initialLine)
                                      throws java.lang.Exception
```
    Throws:
    
    java.lang.Exception
  - createInvalidMessage
```
protected abstract HttpMessage createInvalidMessage()
```

Class HttpObjectDecoder

Parameters that prevents excessive memory consumption

Chunked Content

Extensibility

Nested Class Summary

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

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

Field Summary

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

Constructor Summary

Method Summary

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

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

Methods inherited from class java.lang.Object

Methods inherited from interface io.netty.channel.ChannelHandler

Field Detail

validateHeaders

Constructor Detail

HttpObjectDecoder

HttpObjectDecoder

HttpObjectDecoder

HttpObjectDecoder

Method Detail

decode

decodeLast

userEventTriggered

isContentAlwaysEmpty

isSwitchingToNonHttp1Protocol

reset

handleTransferEncodingChunkedWithContentLength

isDecodingRequest

createMessage

createInvalidMessage