Package io.netty.handler.codec.http

Class 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

    NameDefault valueMeaning
    maxInitialLineLength 4096 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 TooLongHttpLineException will be raised.
    maxHeaderSize 8192 The maximum length of all headers. If the sum of the length of each header exceeds this value, a TooLongHttpHeaderException will be raised.
    maxChunkSize 8192 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 HttpContents whose length is maxChunkSize at maximum.

    Parameters that control parsing behavior

    NameDefault valueMeaning
    allowDuplicateContentLengths false 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 true 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.

    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:
    1. An HttpRequest,
    2. The first HttpContent whose content is 'abcdefghijklmnopqrstuvwxyz',
    3. 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.

    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.

    • Field Detail

      • DEFAULT_MAX_INITIAL_LINE_LENGTH

        public static final int DEFAULT_MAX_INITIAL_LINE_LENGTH
        See Also:
        Constant Field Values

      • DEFAULT_MAX_HEADER_SIZE

        public static final int DEFAULT_MAX_HEADER_SIZE
        See Also:
        Constant Field Values

      • DEFAULT_CHUNKED_SUPPORTED

        public static final boolean DEFAULT_CHUNKED_SUPPORTED
        See Also:
        Constant Field Values

      • DEFAULT_ALLOW_PARTIAL_CHUNKS

        public static final boolean DEFAULT_ALLOW_PARTIAL_CHUNKS
        See Also:
        Constant Field Values

      • DEFAULT_VALIDATE_HEADERS

        public static final boolean DEFAULT_VALIDATE_HEADERS
        See Also:
        Constant Field Values

      • DEFAULT_INITIAL_BUFFER_SIZE

        public static final int DEFAULT_INITIAL_BUFFER_SIZE
        See Also:
        Constant Field Values

      • DEFAULT_ALLOW_DUPLICATE_CONTENT_LENGTHS

        public static final boolean DEFAULT_ALLOW_DUPLICATE_CONTENT_LENGTHS
        See Also:
        Constant Field Values

      • DEFAULT_STRICT_LINE_PARSING

        public static final boolean DEFAULT_STRICT_LINE_PARSING

      • validateHeaders

        @Deprecated
protected final boolean validateHeaders
        Deprecated.
        This field is no longer used. It is only kept around for backwards compatibility purpose.

    • Constructor Detail

      • HttpObjectDecoder

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

      • HttpObjectDecoder

        @Deprecated
protected HttpObjectDecoder​(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported)
        Deprecated.
        Use HttpObjectDecoder(HttpDecoderConfig) instead.
        Creates a new instance with the specified parameters.

      • HttpObjectDecoder

        @Deprecated
protected HttpObjectDecoder​(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders)
        Deprecated.
        Use HttpObjectDecoder(HttpDecoderConfig) instead.
        Creates a new instance with the specified parameters.

      • HttpObjectDecoder

        @Deprecated
protected HttpObjectDecoder​(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders,
                            int initialBufferSize)
        Deprecated.
        Use HttpObjectDecoder(HttpDecoderConfig) instead.
        Creates a new instance with the specified parameters.

      • HttpObjectDecoder

        @Deprecated
protected HttpObjectDecoder​(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders,
                            int initialBufferSize,
                            boolean allowDuplicateContentLengths)
        Deprecated.
        Use HttpObjectDecoder(HttpDecoderConfig) instead.
        Creates a new instance with the specified parameters.

      • HttpObjectDecoder

        @Deprecated
protected HttpObjectDecoder​(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders,
                            int initialBufferSize,
                            boolean allowDuplicateContentLengths,
                            boolean allowPartialChunks)
        Deprecated.
        Use HttpObjectDecoder(HttpDecoderConfig) instead.
        Creates a new instance with the specified parameters.

      • HttpObjectDecoder

        protected HttpObjectDecoder​(HttpDecoderConfig config)
        Creates a new instance with the specified configuration.

    • Method Detail

      • 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()

      • splitFirstWordInitialLine

        protected java.lang.String splitFirstWordInitialLine​(byte[] asciiContent,
                                                     int start,
                                                     int length)

      • splitSecondWordInitialLine

        protected java.lang.String splitSecondWordInitialLine​(byte[] asciiContent,
                                                      int start,
                                                      int length)

      • splitThirdWordInitialLine

        protected java.lang.String splitThirdWordInitialLine​(byte[] asciiContent,
                                                     int start,
                                                     int length)

      • splitHeaderName

        protected AsciiString splitHeaderName​(byte[] sb,
                                      int start,
                                      int length)