PrefaceFrameListener Class — netty Architecture

Source Code

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionDecoder.java lines 696–798

    private final class PrefaceFrameListener implements Http2FrameListener {
        /**
         * Verifies that the HTTP/2 connection preface has been received from the remote endpoint.
         * It is possible that the current call to
         * {@link Http2FrameReader#readFrame(ChannelHandlerContext, ByteBuf, Http2FrameListener)} will have multiple
         * frames to dispatch. So it may be OK for this class to get legitimate frames for the first readFrame.
         */
        private void verifyPrefaceReceived() throws Http2Exception {
            if (!prefaceReceived()) {
                throw connectionError(PROTOCOL_ERROR, "Received non-SETTINGS as first frame.");
            }
        }

        @Override
        public int onDataRead(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding, boolean endOfStream)
                throws Http2Exception {
            verifyPrefaceReceived();
            return internalFrameListener.onDataRead(ctx, streamId, data, padding, endOfStream);
        }

        @Override
        public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding,
                boolean endOfStream) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onHeadersRead(ctx, streamId, headers, padding, endOfStream);
        }

        @Override
        public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency,
                short weight, boolean exclusive, int padding, boolean endOfStream) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onHeadersRead(ctx, streamId, headers, streamDependency, weight,
                    exclusive, padding, endOfStream);
        }

        @Override
        public void onPriorityRead(ChannelHandlerContext ctx, int streamId, int streamDependency, short weight,
                boolean exclusive) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onPriorityRead(ctx, streamId, streamDependency, weight, exclusive);
        }

        @Override
        public void onRstStreamRead(ChannelHandlerContext ctx, int streamId, long errorCode) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onRstStreamRead(ctx, streamId, errorCode);
        }

        @Override
        public void onSettingsAckRead(ChannelHandlerContext ctx) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onSettingsAckRead(ctx);
        }

        @Override
        public void onSettingsRead(ChannelHandlerContext ctx, Http2Settings settings) throws Http2Exception {
            // The first settings should change the internalFrameListener to the "real" listener
            // that expects the preface to be verified.
            if (!prefaceReceived()) {
                internalFrameListener = new FrameReadListener();
            }
            internalFrameListener.onSettingsRead(ctx, settings);
        }

        @Override
        public void onPingRead(ChannelHandlerContext ctx, long data) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onPingRead(ctx, data);
        }

        @Override
        public void onPingAckRead(ChannelHandlerContext ctx, long data) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onPingAckRead(ctx, data);
        }

        @Override
        public void onPushPromiseRead(ChannelHandlerContext ctx, int streamId, int promisedStreamId,
                Http2Headers headers, int padding) throws Http2Exception {
            verifyPrefaceReceived();
            internalFrameListener.onPushPromiseRead(ctx, streamId, promisedStreamId, headers, padding);