src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/internal/frame/FramesEncoder.java - platform/libcore - Gitiles

 /*
  * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package jdk.incubator.http.internal.frame;

 import jdk.incubator.http.internal.common.ByteBufferReference;
 import jdk.incubator.http.internal.common.Utils;

 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;

 /**
  * Frames Encoder
  *
  * Encode framed into ByteBuffers.
  * The class is stateless.
  */
 public class FramesEncoder {


     public FramesEncoder() {
     }

     public ByteBufferReference[] encodeFrames(List<HeaderFrame> frames) {
         List<ByteBufferReference> refs = new ArrayList<>(frames.size() * 2);
         for (HeaderFrame f : frames) {
             refs.addAll(Arrays.asList(encodeFrame(f)));
         }
         return refs.toArray(new ByteBufferReference[0]);
     }

     public ByteBufferReference encodeConnectionPreface(byte[] preface, SettingsFrame frame) {
         final int length = frame.length();
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length + preface.length);
         ByteBuffer buf = ref.get();
         buf.put(preface);
         putSettingsFrame(buf, frame, length);
         buf.flip();
         return ref;
     }

     public ByteBufferReference[] encodeFrame(Http2Frame frame) {
         switch (frame.type()) {
             case DataFrame.TYPE:
                 return encodeDataFrame((DataFrame) frame);
             case HeadersFrame.TYPE:
                 return encodeHeadersFrame((HeadersFrame) frame);
             case PriorityFrame.TYPE:
                 return encodePriorityFrame((PriorityFrame) frame);
             case ResetFrame.TYPE:
                 return encodeResetFrame((ResetFrame) frame);
             case SettingsFrame.TYPE:
                 return encodeSettingsFrame((SettingsFrame) frame);
             case PushPromiseFrame.TYPE:
                 return encodePushPromiseFrame((PushPromiseFrame) frame);
             case PingFrame.TYPE:
                 return encodePingFrame((PingFrame) frame);
             case GoAwayFrame.TYPE:
                 return encodeGoAwayFrame((GoAwayFrame) frame);
             case WindowUpdateFrame.TYPE:
                 return encodeWindowUpdateFrame((WindowUpdateFrame) frame);
             case ContinuationFrame.TYPE:
                 return encodeContinuationFrame((ContinuationFrame) frame);
             default:
                 throw new UnsupportedOperationException("Not supported frame "+frame.type()+" ("+frame.getClass().getName()+")");
         }
     }

     private static final int NO_FLAGS = 0;
     private static final int ZERO_STREAM = 0;

     private ByteBufferReference[] encodeDataFrame(DataFrame frame) {
         // non-zero stream
         assert frame.streamid() != 0;
         ByteBufferReference ref = encodeDataFrameStart(frame);
         if (frame.getFlag(DataFrame.PADDED)) {
             return joinWithPadding(ref, frame.getData(), frame.getPadLength());
         } else {
             return join(ref, frame.getData());
         }
     }

     private ByteBufferReference encodeDataFrameStart(DataFrame frame) {
         boolean isPadded = frame.getFlag(DataFrame.PADDED);
         final int length = frame.getDataLength() + (isPadded ? (frame.getPadLength() + 1) : 0);
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 1 : 0));
         ByteBuffer buf = ref.get();
         putHeader(buf, length, DataFrame.TYPE, frame.getFlags(), frame.streamid());
         if (isPadded) {
             buf.put((byte) frame.getPadLength());
         }
         buf.flip();
         return ref;
     }

     private ByteBufferReference[] encodeHeadersFrame(HeadersFrame frame) {
         // non-zero stream
         assert frame.streamid() != 0;
         ByteBufferReference ref = encodeHeadersFrameStart(frame);
         if (frame.getFlag(HeadersFrame.PADDED)) {
             return joinWithPadding(ref, frame.getHeaderBlock(), frame.getPadLength());
         } else {
             return join(ref, frame.getHeaderBlock());
         }
     }

     private ByteBufferReference encodeHeadersFrameStart(HeadersFrame frame) {
         boolean isPadded = frame.getFlag(HeadersFrame.PADDED);
         boolean hasPriority = frame.getFlag(HeadersFrame.PRIORITY);
         final int length = frame.getHeaderLength() + (isPadded ? (frame.getPadLength() + 1) : 0) + (hasPriority ? 5 : 0);
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 1 : 0) + (hasPriority ? 5 : 0));
         ByteBuffer buf = ref.get();
         putHeader(buf, length, HeadersFrame.TYPE, frame.getFlags(), frame.streamid());
         if (isPadded) {
             buf.put((byte) frame.getPadLength());
         }
         if (hasPriority) {
             putPriority(buf, frame.getExclusive(), frame.getStreamDependency(), frame.getWeight());
         }
         buf.flip();
         return ref;
     }

     private ByteBufferReference[] encodePriorityFrame(PriorityFrame frame) {
         // non-zero stream; no flags
         assert frame.streamid() != 0;
         final int length = 5;
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, PriorityFrame.TYPE, NO_FLAGS, frame.streamid());
         putPriority(buf, frame.exclusive(), frame.streamDependency(), frame.weight());
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodeResetFrame(ResetFrame frame) {
         // non-zero stream; no flags
         assert frame.streamid() != 0;
         final int length = 4;
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, ResetFrame.TYPE, NO_FLAGS, frame.streamid());
         buf.putInt(frame.getErrorCode());
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodeSettingsFrame(SettingsFrame frame) {
         // only zero stream
         assert frame.streamid() == 0;
         final int length = frame.length();
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putSettingsFrame(buf, frame, length);
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodePushPromiseFrame(PushPromiseFrame frame) {
         // non-zero stream
         assert frame.streamid() != 0;
         boolean isPadded = frame.getFlag(PushPromiseFrame.PADDED);
         final int length = frame.getHeaderLength() + (isPadded ? 5 : 4);
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 5 : 4));
         ByteBuffer buf = ref.get();
         putHeader(buf, length, PushPromiseFrame.TYPE, frame.getFlags(), frame.streamid());
         if (isPadded) {
             buf.put((byte) frame.getPadLength());
         }
         buf.putInt(frame.getPromisedStream());
         buf.flip();

         if (frame.getFlag(PushPromiseFrame.PADDED)) {
             return joinWithPadding(ref, frame.getHeaderBlock(), frame.getPadLength());
         } else {
             return join(ref, frame.getHeaderBlock());
         }
     }

     private ByteBufferReference[] encodePingFrame(PingFrame frame) {
         // only zero stream
         assert frame.streamid() == 0;
         final int length = 8;
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, PingFrame.TYPE, frame.getFlags(), ZERO_STREAM);
         buf.put(frame.getData());
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodeGoAwayFrame(GoAwayFrame frame) {
         // only zero stream; no flags
         assert frame.streamid() == 0;
         byte[] debugData = frame.getDebugData();
         final int length = 8 + debugData.length;
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, GoAwayFrame.TYPE, NO_FLAGS, ZERO_STREAM);
         buf.putInt(frame.getLastStream());
         buf.putInt(frame.getErrorCode());
         if (debugData.length > 0) {
             buf.put(debugData);
         }
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodeWindowUpdateFrame(WindowUpdateFrame frame) {
         // any stream; no flags
         final int length = 4;
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, WindowUpdateFrame.TYPE, NO_FLAGS, frame.streamid);
         buf.putInt(frame.getUpdate());
         buf.flip();
         return new ByteBufferReference[]{ref};
     }

     private ByteBufferReference[] encodeContinuationFrame(ContinuationFrame frame) {
         // non-zero stream;
         assert frame.streamid() != 0;
         final int length = frame.getHeaderLength();
         ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE);
         ByteBuffer buf = ref.get();
         putHeader(buf, length, ContinuationFrame.TYPE, frame.getFlags(), frame.streamid());
         buf.flip();
         return join(ref, frame.getHeaderBlock());
     }

     private ByteBufferReference[] joinWithPadding(ByteBufferReference ref, ByteBufferReference[] data, int padLength) {
         ByteBufferReference[] references = new ByteBufferReference[2 + data.length];
         references[0] = ref;
         System.arraycopy(data, 0, references, 1, data.length);
         assert references[references.length - 1] == null;
         references[references.length - 1] = getPadding(padLength);
         return references;
     }

     private ByteBufferReference[] join(ByteBufferReference ref, ByteBufferReference[] data) {
         ByteBufferReference[] references = new ByteBufferReference[1 + data.length];
         references[0] = ref;
         System.arraycopy(data, 0, references, 1, data.length);
         return references;
     }

     private void putSettingsFrame(ByteBuffer buf, SettingsFrame frame, int length) {
         // only zero stream;
         assert frame.streamid() == 0;
         putHeader(buf, length, SettingsFrame.TYPE, frame.getFlags(), ZERO_STREAM);
         frame.toByteBuffer(buf);
     }

     private void putHeader(ByteBuffer buf, int length, int type, int flags, int streamId) {
         int x = (length << 8) + type;
         buf.putInt(x);
         buf.put((byte) flags);
         buf.putInt(streamId);
     }

     private void putPriority(ByteBuffer buf, boolean exclusive, int streamDependency, int weight) {
         buf.putInt(exclusive ? (1 << 31) + streamDependency : streamDependency);
         buf.put((byte) weight);
     }

     private ByteBufferReference getBuffer(int capacity) {
         return ByteBufferReference.of(ByteBuffer.allocate(capacity));
     }

     public ByteBufferReference getPadding(int length) {
         if (length > 255) {
             throw new IllegalArgumentException("Padding too big");
         }
         return ByteBufferReference.of(ByteBuffer.allocate(length)); // zeroed!
     }

 }
	/*
	* Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package jdk.incubator.http.internal.frame;

	import jdk.incubator.http.internal.common.ByteBufferReference;
	import jdk.incubator.http.internal.common.Utils;

	import java.nio.ByteBuffer;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;

	/**
	* Frames Encoder
	*
	* Encode framed into ByteBuffers.
	* The class is stateless.
	*/
	public class FramesEncoder {


	public FramesEncoder() {
	}

	public ByteBufferReference[] encodeFrames(List<HeaderFrame> frames) {
	List<ByteBufferReference> refs = new ArrayList<>(frames.size() * 2);
	for (HeaderFrame f : frames) {
	refs.addAll(Arrays.asList(encodeFrame(f)));
	}
	return refs.toArray(new ByteBufferReference[0]);
	}

	public ByteBufferReference encodeConnectionPreface(byte[] preface, SettingsFrame frame) {
	final int length = frame.length();
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length + preface.length);
	ByteBuffer buf = ref.get();
	buf.put(preface);
	putSettingsFrame(buf, frame, length);
	buf.flip();
	return ref;
	}

	public ByteBufferReference[] encodeFrame(Http2Frame frame) {
	switch (frame.type()) {
	case DataFrame.TYPE:
	return encodeDataFrame((DataFrame) frame);
	case HeadersFrame.TYPE:
	return encodeHeadersFrame((HeadersFrame) frame);
	case PriorityFrame.TYPE:
	return encodePriorityFrame((PriorityFrame) frame);
	case ResetFrame.TYPE:
	return encodeResetFrame((ResetFrame) frame);
	case SettingsFrame.TYPE:
	return encodeSettingsFrame((SettingsFrame) frame);
	case PushPromiseFrame.TYPE:
	return encodePushPromiseFrame((PushPromiseFrame) frame);
	case PingFrame.TYPE:
	return encodePingFrame((PingFrame) frame);
	case GoAwayFrame.TYPE:
	return encodeGoAwayFrame((GoAwayFrame) frame);
	case WindowUpdateFrame.TYPE:
	return encodeWindowUpdateFrame((WindowUpdateFrame) frame);
	case ContinuationFrame.TYPE:
	return encodeContinuationFrame((ContinuationFrame) frame);
	default:
	throw new UnsupportedOperationException("Not supported frame "+frame.type()+" ("+frame.getClass().getName()+")");
	}
	}

	private static final int NO_FLAGS = 0;
	private static final int ZERO_STREAM = 0;

	private ByteBufferReference[] encodeDataFrame(DataFrame frame) {
	// non-zero stream
	assert frame.streamid() != 0;
	ByteBufferReference ref = encodeDataFrameStart(frame);
	if (frame.getFlag(DataFrame.PADDED)) {
	return joinWithPadding(ref, frame.getData(), frame.getPadLength());
	} else {
	return join(ref, frame.getData());
	}
	}

	private ByteBufferReference encodeDataFrameStart(DataFrame frame) {
	boolean isPadded = frame.getFlag(DataFrame.PADDED);
	final int length = frame.getDataLength() + (isPadded ? (frame.getPadLength() + 1) : 0);
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 1 : 0));
	ByteBuffer buf = ref.get();
	putHeader(buf, length, DataFrame.TYPE, frame.getFlags(), frame.streamid());
	if (isPadded) {
	buf.put((byte) frame.getPadLength());
	}
	buf.flip();
	return ref;
	}

	private ByteBufferReference[] encodeHeadersFrame(HeadersFrame frame) {
	// non-zero stream
	assert frame.streamid() != 0;
	ByteBufferReference ref = encodeHeadersFrameStart(frame);
	if (frame.getFlag(HeadersFrame.PADDED)) {
	return joinWithPadding(ref, frame.getHeaderBlock(), frame.getPadLength());
	} else {
	return join(ref, frame.getHeaderBlock());
	}
	}

	private ByteBufferReference encodeHeadersFrameStart(HeadersFrame frame) {
	boolean isPadded = frame.getFlag(HeadersFrame.PADDED);
	boolean hasPriority = frame.getFlag(HeadersFrame.PRIORITY);
	final int length = frame.getHeaderLength() + (isPadded ? (frame.getPadLength() + 1) : 0) + (hasPriority ? 5 : 0);
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 1 : 0) + (hasPriority ? 5 : 0));
	ByteBuffer buf = ref.get();
	putHeader(buf, length, HeadersFrame.TYPE, frame.getFlags(), frame.streamid());
	if (isPadded) {
	buf.put((byte) frame.getPadLength());
	}
	if (hasPriority) {
	putPriority(buf, frame.getExclusive(), frame.getStreamDependency(), frame.getWeight());
	}
	buf.flip();
	return ref;
	}

	private ByteBufferReference[] encodePriorityFrame(PriorityFrame frame) {
	// non-zero stream; no flags
	assert frame.streamid() != 0;
	final int length = 5;
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, PriorityFrame.TYPE, NO_FLAGS, frame.streamid());
	putPriority(buf, frame.exclusive(), frame.streamDependency(), frame.weight());
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodeResetFrame(ResetFrame frame) {
	// non-zero stream; no flags
	assert frame.streamid() != 0;
	final int length = 4;
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, ResetFrame.TYPE, NO_FLAGS, frame.streamid());
	buf.putInt(frame.getErrorCode());
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodeSettingsFrame(SettingsFrame frame) {
	// only zero stream
	assert frame.streamid() == 0;
	final int length = frame.length();
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putSettingsFrame(buf, frame, length);
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodePushPromiseFrame(PushPromiseFrame frame) {
	// non-zero stream
	assert frame.streamid() != 0;
	boolean isPadded = frame.getFlag(PushPromiseFrame.PADDED);
	final int length = frame.getHeaderLength() + (isPadded ? 5 : 4);
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + (isPadded ? 5 : 4));
	ByteBuffer buf = ref.get();
	putHeader(buf, length, PushPromiseFrame.TYPE, frame.getFlags(), frame.streamid());
	if (isPadded) {
	buf.put((byte) frame.getPadLength());
	}
	buf.putInt(frame.getPromisedStream());
	buf.flip();

	if (frame.getFlag(PushPromiseFrame.PADDED)) {
	return joinWithPadding(ref, frame.getHeaderBlock(), frame.getPadLength());
	} else {
	return join(ref, frame.getHeaderBlock());
	}
	}

	private ByteBufferReference[] encodePingFrame(PingFrame frame) {
	// only zero stream
	assert frame.streamid() == 0;
	final int length = 8;
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, PingFrame.TYPE, frame.getFlags(), ZERO_STREAM);
	buf.put(frame.getData());
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodeGoAwayFrame(GoAwayFrame frame) {
	// only zero stream; no flags
	assert frame.streamid() == 0;
	byte[] debugData = frame.getDebugData();
	final int length = 8 + debugData.length;
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, GoAwayFrame.TYPE, NO_FLAGS, ZERO_STREAM);
	buf.putInt(frame.getLastStream());
	buf.putInt(frame.getErrorCode());
	if (debugData.length > 0) {
	buf.put(debugData);
	}
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodeWindowUpdateFrame(WindowUpdateFrame frame) {
	// any stream; no flags
	final int length = 4;
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE + length);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, WindowUpdateFrame.TYPE, NO_FLAGS, frame.streamid);
	buf.putInt(frame.getUpdate());
	buf.flip();
	return new ByteBufferReference[]{ref};
	}

	private ByteBufferReference[] encodeContinuationFrame(ContinuationFrame frame) {
	// non-zero stream;
	assert frame.streamid() != 0;
	final int length = frame.getHeaderLength();
	ByteBufferReference ref = getBuffer(Http2Frame.FRAME_HEADER_SIZE);
	ByteBuffer buf = ref.get();
	putHeader(buf, length, ContinuationFrame.TYPE, frame.getFlags(), frame.streamid());
	buf.flip();
	return join(ref, frame.getHeaderBlock());
	}

	private ByteBufferReference[] joinWithPadding(ByteBufferReference ref, ByteBufferReference[] data, int padLength) {
	ByteBufferReference[] references = new ByteBufferReference[2 + data.length];
	references[0] = ref;
	System.arraycopy(data, 0, references, 1, data.length);
	assert references[references.length - 1] == null;
	references[references.length - 1] = getPadding(padLength);
	return references;
	}

	private ByteBufferReference[] join(ByteBufferReference ref, ByteBufferReference[] data) {
	ByteBufferReference[] references = new ByteBufferReference[1 + data.length];
	references[0] = ref;
	System.arraycopy(data, 0, references, 1, data.length);
	return references;
	}

	private void putSettingsFrame(ByteBuffer buf, SettingsFrame frame, int length) {
	// only zero stream;
	assert frame.streamid() == 0;
	putHeader(buf, length, SettingsFrame.TYPE, frame.getFlags(), ZERO_STREAM);
	frame.toByteBuffer(buf);
	}

	private void putHeader(ByteBuffer buf, int length, int type, int flags, int streamId) {
	int x = (length << 8) + type;
	buf.putInt(x);
	buf.put((byte) flags);
	buf.putInt(streamId);
	}

	private void putPriority(ByteBuffer buf, boolean exclusive, int streamDependency, int weight) {
	buf.putInt(exclusive ? (1 << 31) + streamDependency : streamDependency);
	buf.put((byte) weight);
	}

	private ByteBufferReference getBuffer(int capacity) {
	return ByteBufferReference.of(ByteBuffer.allocate(capacity));
	}

	public ByteBufferReference getPadding(int length) {
	if (length > 255) {
	throw new IllegalArgumentException("Padding too big");
	}
	return ByteBufferReference.of(ByteBuffer.allocate(length)); // zeroed!
	}

	}