tomcat9.0源码分析之解码Http/2 DataFrame

Http2Parser#readDataFrame()方法

protected void readDataFrame(int streamId, int flags, int payloadSize, ByteBuffer buffer)
            throws Http2Exception, IOException {
        // Process the Stream
        int padLength = 0;

        boolean endOfStream = Flags.isEndOfStream(flags);

        int dataLength;
        if (Flags.hasPadding(flags)) {
            if (buffer == null) {
                byte[] b = new byte[1];
                input.fill(true, b);
                padLength = b[0] & 0xFF;
            } else {
                padLength = buffer.get() & 0xFF;
            }

            if (padLength >= payloadSize) {
                throw new ConnectionException(
                        sm.getString("http2Parser.processFrame.tooMuchPadding", connectionId,
                                Integer.toString(streamId), Integer.toString(padLength),
                                Integer.toString(payloadSize)), Http2Error.PROTOCOL_ERROR);
            }
            // +1 is for the padding length byte we just read above
            dataLength = payloadSize - (padLength + 1);
        } else {
            dataLength = payloadSize;
        }

        if (log.isDebugEnabled()) {
            String padding;
            if (Flags.hasPadding(flags)) {
                padding = Integer.toString(padLength);
            } else {
                padding = "none";
            }
            log.debug(sm.getString("http2Parser.processFrameData.lengths", connectionId,
                    Integer.toString(streamId), Integer.toString(dataLength), padding));
        }

        ByteBuffer dest = output.startRequestBodyFrame(streamId, payloadSize);
        if (dest == null) {
            swallow(streamId, dataLength, false, buffer);
            // Process padding before sending any notifications in case padding
            // is invalid.
            if (padLength > 0) {
                swallow(streamId, padLength, true, buffer);
            }
            if (endOfStream) {
                output.receivedEndOfStream(streamId);
            }
        } else {
            synchronized (dest) {
                if (dest.remaining() < dataLength) {
                    swallow(streamId, dataLength, false, buffer);
                    // Client has sent more data than permitted by Window size
                    throw new StreamException(sm.getString("http2Parser.processFrameData.window", connectionId),
                            Http2Error.FLOW_CONTROL_ERROR, streamId);
                }
                if (buffer == null) {
                    input.fill(true, dest, dataLength);
                } else {
                    int oldLimit = buffer.limit();
                    buffer.limit(buffer.position() + dataLength);
                    dest.put(buffer);
                    buffer.limit(oldLimit);
                }
                // Process padding before sending any notifications in case
                // padding is invalid.
                if (padLength > 0) {
                    swallow(streamId, padLength, true, buffer);
                }
                if (endOfStream) {
                    output.receivedEndOfStream(streamId);
                }
                output.endRequestBodyFrame(streamId);
            }
        }
        if (padLength > 0) {
            output.swallowedPadding(streamId, padLength);
        }
    }