WebSocket08FrameDecoder Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocket08FrameDecoder.java lines 75–492

public class WebSocket08FrameDecoder extends ByteToMessageDecoder
        implements WebSocketFrameDecoder {

    enum State {
        READING_FIRST,
        READING_SECOND,
        READING_SIZE,
        MASKING_KEY,
        PAYLOAD,
        CORRUPT
    }

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(WebSocket08FrameDecoder.class);

    private static final byte OPCODE_CONT = 0x0;
    private static final byte OPCODE_TEXT = 0x1;
    private static final byte OPCODE_BINARY = 0x2;
    private static final byte OPCODE_CLOSE = 0x8;
    private static final byte OPCODE_PING = 0x9;
    private static final byte OPCODE_PONG = 0xA;

    private final WebSocketDecoderConfig config;

    private int fragmentedFramesCount;
    private boolean frameFinalFlag;
    private boolean frameMasked;
    private int frameRsv;
    private int frameOpcode;
    private long framePayloadLength;
    private int mask;
    private int framePayloadLen1;
    private boolean receivedClosingHandshake;
    private State state = State.READING_FIRST;

    /**
     * Constructor
     *
     * @param expectMaskedFrames
     *            Web socket servers must set this to true processed incoming masked payload. Client implementations
     *            must set this to false.
     * @param allowExtensions
     *            Flag to allow reserved extension bits to be used or not
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload. Setting this to an appropriate value for you application
     *            helps check for denial of services attacks.
     */
    public WebSocket08FrameDecoder(boolean expectMaskedFrames, boolean allowExtensions, int maxFramePayloadLength) {
        this(expectMaskedFrames, allowExtensions, maxFramePayloadLength, false);
    }

    /**
     * Constructor
     *
     * @param expectMaskedFrames
     *            Web socket servers must set this to true processed incoming masked payload. Client implementations
     *            must set this to false.
     * @param allowExtensions
     *            Flag to allow reserved extension bits to be used or not
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload. Setting this to an appropriate value for you application
     *            helps check for denial of services attacks.
     * @param allowMaskMismatch
     *            When set to true, frames which are not masked properly according to the standard will still be
     *            accepted.
     */
    public WebSocket08FrameDecoder(boolean expectMaskedFrames, boolean allowExtensions, int maxFramePayloadLength,
                                   boolean allowMaskMismatch) {
        this(WebSocketDecoderConfig.newBuilder()
            .expectMaskedFrames(expectMaskedFrames)
            .allowExtensions(allowExtensions)
            .maxFramePayloadLength(maxFramePayloadLength)
            .allowMaskMismatch(allowMaskMismatch)
            .build());
    }

    /**
     * Constructor
     *
     * @param decoderConfig
     *            Frames decoder configuration.
     */