Add PushPromise and Priority Frame support in Http2FrameCodec (#10765)

Motivation:
Right now, we don't have to handle Push Promise Read in `Http2FrameCodec`. Push Promise is one of the key features of HTTP/2 and we should support it in our `Http2FrameCodec`.

Modification:
Added `Http2PushPromiseFrame` and `Http2PushPromiseFrame` to handle Push Promise and Promise Frame.

Result:
Fixes #10748

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2PriorityFrame.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2020 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http2;
+
+import io.netty.util.internal.UnstableApi;
+
+/**
+ * Default implementation of {@linkplain Http2PriorityFrame}
+ */
+@UnstableApi
+public final class DefaultHttp2PriorityFrame implements Http2PriorityFrame {
+
+    private final int streamDependency;
+    private final short weight;
+    private final boolean exclusive;
+    private Http2FrameStream http2FrameStream;
+
+    public DefaultHttp2PriorityFrame(int streamDependency, short weight, boolean exclusive) {
+        this.streamDependency = streamDependency;
+        this.weight = weight;
+        this.exclusive = exclusive;
+    }
+
+    @Override
+    public int streamDependency() {
+        return streamDependency;
+    }
+
+    @Override
+    public short weight() {
+        return weight;
+    }
+
+    @Override
+    public boolean exclusive() {
+        return exclusive;
+    }
+
+    @Override
+    public Http2PriorityFrame stream(Http2FrameStream stream) {
+        http2FrameStream = stream;
+        return this;
+    }
+
+    @Override
+    public Http2FrameStream stream() {
+        return http2FrameStream;
+    }
+
+    @Override
+    public String name() {
+        return "PRIORITY_FRAME";
+    }
+
+    @Override
+    public String toString() {
+        return "DefaultHttp2PriorityFrame(" +
+                "stream=" + http2FrameStream +
+                ", streamDependency=" + streamDependency +
+                ", weight=" + weight +
+                ", exclusive=" + exclusive +
+                ')';
+    }
+}

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2PushPromiseFrame.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2020 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http2;
+
+import io.netty.util.internal.UnstableApi;
+
+/**
+ * Default implementation of {@link Http2PushPromiseFrame}
+ */
+@UnstableApi
+public final class DefaultHttp2PushPromiseFrame implements Http2PushPromiseFrame {
+
+    private Http2FrameStream pushStreamFrame;
+    private final Http2Headers http2Headers;
+    private Http2FrameStream streamFrame;
+    private final int padding;
+    private final int promisedStreamId;
+
+    public DefaultHttp2PushPromiseFrame(Http2Headers http2Headers) {
+        this(http2Headers, 0);
+    }
+
+    public DefaultHttp2PushPromiseFrame(Http2Headers http2Headers, int padding) {
+        this(http2Headers, padding, -1);
+    }
+
+    DefaultHttp2PushPromiseFrame(Http2Headers http2Headers, int padding, int promisedStreamId) {
+        this.http2Headers = http2Headers;
+        this.padding = padding;
+        this.promisedStreamId = promisedStreamId;
+    }
+
+    @Override
+    public Http2StreamFrame pushStream(Http2FrameStream stream) {
+        pushStreamFrame = stream;
+        return this;
+    }
+
+    @Override
+    public Http2FrameStream pushStream() {
+        return pushStreamFrame;
+    }
+
+    @Override
+    public Http2Headers http2Headers() {
+        return http2Headers;
+    }
+
+    @Override
+    public int padding() {
+        return padding;
+    }
+
+    @Override
+    public int promisedStreamId() {
+        if (pushStreamFrame != null) {
+            return pushStreamFrame.id();
+        } else {
+            return promisedStreamId;
+        }
+    }
+
+    @Override
+    public Http2PushPromiseFrame stream(Http2FrameStream stream) {
+        streamFrame = stream;
+        return this;
+    }
+
+    @Override
+    public Http2FrameStream stream() {
+        return streamFrame;
+    }
+
+    @Override
+    public String name() {
+        return "PUSH_PROMISE_FRAME";
+    }
+
+    @Override
+    public String toString() {
+        return "DefaultHttp2PushPromiseFrame{" +
+                "pushStreamFrame=" + pushStreamFrame +
+                ", http2Headers=" + http2Headers +
+                ", streamFrame=" + streamFrame +
+                ", padding=" + padding +
+                '}';
+    }
+}

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2FrameCodec.java

@@ -17,6 +17,7 @@ package io.netty.handler.codec.http2;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
@@ -54,7 +55,7 @@ import static io.netty.handler.codec.http2.Http2Error.NO_ERROR;
  * creating outbound streams.
  *
  * <h3>Stream Lifecycle</h3>
- *
+ * <p>
  * The frame codec delivers and writes frames for active streams. An active stream is closed when either side sends a
  * {@code RST_STREAM} frame or both sides send a frame with the {@code END_STREAM} flag set. Each
  * {@link Http2StreamFrame} has a {@link Http2FrameStream} object attached that uniquely identifies a particular stream.
@@ -64,7 +65,7 @@ import static io.netty.handler.codec.http2.Http2Error.NO_ERROR;
  * {@link Http2StreamFrame#stream(Http2FrameStream)}.
  *
  * <h3>Flow control</h3>
- *
+ * <p>
  * The frame codec automatically increments stream and connection flow control windows.
  *
  * <p>Incoming flow controlled frames need to be consumed by writing a {@link Http2WindowUpdateFrame} with the consumed
@@ -78,12 +79,12 @@ import static io.netty.handler.codec.http2.Http2Error.NO_ERROR;
  * connection-level flow control window is the same as initial stream-level flow control window.
  *
  * <h3>New inbound Streams</h3>
- *
+ * <p>
  * The first frame of an HTTP/2 stream must be an {@link Http2HeadersFrame}, which will have an {@link Http2FrameStream}
  * object attached.
  *
  * <h3>New outbound Streams</h3>
- *
+ * <p>
  * A outbound HTTP/2 stream can be created by first instantiating a new {@link Http2FrameStream} object via
  * {@link Http2ChannelDuplexHandler#newStream()}, and then writing a {@link Http2HeadersFrame} object with the stream
  * attached.
@@ -125,13 +126,13 @@ import static io.netty.handler.codec.http2.Http2Error.NO_ERROR;
  * the last stream identifier of the GO_AWAY frame will fail with a {@link Http2GoAwayException}.
  *
  * <h3>Error Handling</h3>
- *
+ * <p>
  * Exceptions and errors are propagated via {@link ChannelHandler#exceptionCaught}. Exceptions that apply to
  * a specific HTTP/2 stream are wrapped in a {@link Http2FrameStreamException} and have the corresponding
  * {@link Http2FrameStream} object attached.
  *
  * <h3>Reference Counting</h3>
- *
+ * <p>
  * Some {@link Http2StreamFrame}s implement the {@link ReferenceCounted} interface, as they carry
  * reference counted objects (e.g. {@link ByteBuf}s). The frame codec will call {@link ReferenceCounted#retain()} before
  * propagating a reference counted object through the pipeline, and thus an application handler needs to release such
@@ -139,7 +140,7 @@ import static io.netty.handler.codec.http2.Http2Error.NO_ERROR;
  * https://netty.io/wiki/reference-counted-objects.html
  *
  * <h3>HTTP Upgrade</h3>
- *
+ * <p>
  * Server-side HTTP to HTTP/2 upgrade is supported in conjunction with {@link Http2ServerUpgradeCodec}; the necessary
  * HTTP-to-HTTP/2 conversion is performed automatically.
  */
@@ -155,7 +156,9 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
 
     ChannelHandlerContext ctx;
 
-    /** Number of buffered streams if the {@link StreamBufferingEncoder} is used. **/
+    /**
+     * Number of buffered streams if the {@link StreamBufferingEncoder} is used.
+     **/
     private int numBufferedStreams;
     private final IntObjectMap<DefaultHttp2FrameStream> frameStreamToInitializeMap =
             new IntObjectHashMap<DefaultHttp2FrameStream>(8);
@@ -201,7 +204,7 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
 
     /**
      * Retrieve the number of streams currently in the process of being initialized.
-     *
+     * <p>
      * This is package-private for testing only.
      */
     int numInitializingStreams() {
@@ -324,6 +327,13 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
             encoder().writeSettingsAck(ctx, promise);
         } else if (msg instanceof Http2GoAwayFrame) {
             writeGoAwayFrame(ctx, (Http2GoAwayFrame) msg, promise);
+        } else if (msg instanceof Http2PushPromiseFrame) {
+            Http2PushPromiseFrame pushPromiseFrame = (Http2PushPromiseFrame) msg;
+            writePushPromise(ctx, pushPromiseFrame, promise);
+        } else if (msg instanceof Http2PriorityFrame) {
+            Http2PriorityFrame priorityFrame = (Http2PriorityFrame) msg;
+            encoder().writePriority(ctx, priorityFrame.stream().id(), priorityFrame.streamDependency(),
+                    priorityFrame.weight(), priorityFrame.exclusive(), promise);
         } else if (msg instanceof Http2UnknownFrame) {
             Http2UnknownFrame unknownFrame = (Http2UnknownFrame) msg;
             encoder().writeFrame(ctx, unknownFrame.frameType(), unknownFrame.stream().id(),
@@ -370,37 +380,14 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
         goAway(ctx, (int) lastStreamId, frame.errorCode(), frame.content(), promise);
     }
 
-    private void writeHeadersFrame(
-            final ChannelHandlerContext ctx, Http2HeadersFrame headersFrame, final ChannelPromise promise) {
+    private void writeHeadersFrame(final ChannelHandlerContext ctx, Http2HeadersFrame headersFrame,
+                                   final ChannelPromise promise) {
 
         if (isStreamIdValid(headersFrame.stream().id())) {
             encoder().writeHeaders(ctx, headersFrame.stream().id(), headersFrame.headers(), headersFrame.padding(),
                     headersFrame.isEndStream(), promise);
-        } else {
-            final DefaultHttp2FrameStream stream = (DefaultHttp2FrameStream) headersFrame.stream();
-            final Http2Connection connection = connection();
-            final int streamId = connection.local().incrementAndGetNextStreamId();
-            if (streamId < 0) {
-                promise.setFailure(new Http2NoMoreStreamIdsException());
-
-                // Simulate a GOAWAY being received due to stream exhaustion on this connection. We use the maximum
-                // valid stream ID for the current peer.
-                onHttp2Frame(ctx, new DefaultHttp2GoAwayFrame(connection.isServer() ? Integer.MAX_VALUE :
-                        Integer.MAX_VALUE - 1, NO_ERROR.code(),
-                        writeAscii(ctx.alloc(), "Stream IDs exhausted on local stream creation")));
-                return;
-            }
-            stream.id = streamId;
-
-            // Use a Map to store all pending streams as we may have multiple. This is needed as if we would store the
-            // stream in a field directly we may override the stored field before onStreamAdded(...) was called
-            // and so not correctly set the property for the buffered stream.
-            //
-            // See https://github.com/netty/netty/issues/8692
-            Object old = frameStreamToInitializeMap.put(streamId, stream);
-
-            // We should not re-use ids.
-            assert old == null;
+        } else if (initializeNewStream(ctx, (DefaultHttp2FrameStream) headersFrame.stream(), promise)) {
+            final int streamId = headersFrame.stream().id();
 
             encoder().writeHeaders(ctx, streamId, headersFrame.headers(), headersFrame.padding(),
                     headersFrame.isEndStream(), promise);
@@ -420,6 +407,59 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
         }
     }
 
+    private void writePushPromise(final ChannelHandlerContext ctx, Http2PushPromiseFrame pushPromiseFrame,
+                                  final ChannelPromise promise) {
+        if (isStreamIdValid(pushPromiseFrame.pushStream().id())) {
+            encoder().writePushPromise(ctx, pushPromiseFrame.stream().id(), pushPromiseFrame.pushStream().id(),
+                    pushPromiseFrame.http2Headers(), pushPromiseFrame.padding(), promise);
+        } else if (initializeNewStream(ctx, (DefaultHttp2FrameStream) pushPromiseFrame.pushStream(), promise)) {
+            final int streamId = pushPromiseFrame.stream().id();
+            encoder().writePushPromise(ctx, streamId, pushPromiseFrame.pushStream().id(),
+                    pushPromiseFrame.http2Headers(), pushPromiseFrame.padding(), promise);
+
+            if (promise.isDone()) {
+                handleHeaderFuture(promise, streamId);
+            } else {
+                numBufferedStreams++;
+                // Clean up the stream being initialized if writing the headers fails and also
+                // decrement the number of buffered streams.
+                promise.addListener((ChannelFuture f) -> {
+                    numBufferedStreams--;
+                    handleHeaderFuture(f, streamId);
+                });
+            }
+        }
+    }
+
+    private boolean initializeNewStream(ChannelHandlerContext ctx, DefaultHttp2FrameStream http2FrameStream,
+                                        ChannelPromise promise) {
+        final Http2Connection connection = connection();
+        final int streamId = connection.local().incrementAndGetNextStreamId();
+        if (streamId < 0) {
+            promise.setFailure(new Http2NoMoreStreamIdsException());
+
+            // Simulate a GOAWAY being received due to stream exhaustion on this connection. We use the maximum
+            // valid stream ID for the current peer.
+            onHttp2Frame(ctx, new DefaultHttp2GoAwayFrame(connection.isServer() ? Integer.MAX_VALUE :
+                    Integer.MAX_VALUE - 1, NO_ERROR.code(),
+                    writeAscii(ctx.alloc(), "Stream IDs exhausted on local stream creation")));
+
+            return false;
+        }
+        http2FrameStream.id = streamId;
+
+        // Use a Map to store all pending streams as we may have multiple. This is needed as if we would store the
+        // stream in a field directly we may override the stored field before onStreamAdded(...) was called
+        // and so not correctly set the property for the buffered stream.
+        //
+        // See https://github.com/netty/netty/issues/8692
+        Object old = frameStreamToInitializeMap.put(streamId, http2FrameStream);
+
+        // We should not re-use ids.
+        assert old == null;
+        return true;
+    }
+
     private void handleHeaderFuture(Future<?> channelFuture, int streamId) {
         if (!channelFuture.isSuccess()) {
             frameStreamToInitializeMap.remove(streamId);
@@ -488,7 +528,7 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
      */
     @Override
     protected final void onStreamError(ChannelHandlerContext ctx, boolean outbound, Throwable cause,
-                                 Http2Exception.StreamException streamException) {
+                                       Http2Exception.StreamException streamException) {
         int streamId = streamException.streamId();
         Http2Stream connectionStream = connection().stream(streamId);
         if (connectionStream == null) {
@@ -513,12 +553,12 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
     }
 
     private void onHttp2UnknownStreamError(@SuppressWarnings("unused") ChannelHandlerContext ctx, Throwable cause,
-                                   Http2Exception.StreamException streamException) {
+                                           Http2Exception.StreamException streamException) {
         // It is normal to hit a race condition where we still receive frames for a stream that this
         // peer has deemed closed, such as if this peer sends a RST(CANCEL) to discard the request.
         // Since this is likely to be normal we log at DEBUG level.
         InternalLogLevel level =
-            streamException.error() == Http2Error.STREAM_CLOSED ? InternalLogLevel.DEBUG : InternalLogLevel.WARN;
+                streamException.error() == Http2Error.STREAM_CLOSED ? InternalLogLevel.DEBUG : InternalLogLevel.WARN;
         LOG.log(level, "Stream exception thrown for unknown stream {}.", streamException.streamId(), cause);
     }
 
@@ -580,14 +620,14 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
         public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers,
                                   int padding, boolean endOfStream) {
             onHttp2Frame(ctx, new DefaultHttp2HeadersFrame(headers, endOfStream, padding)
-                                        .stream(requireStream(streamId)));
+                    .stream(requireStream(streamId)));
         }
 
         @Override
         public int onDataRead(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding,
                               boolean endOfStream) {
             onHttp2Frame(ctx, new DefaultHttp2DataFrame(data, endOfStream, padding)
-                                        .stream(requireStream(streamId)).retain());
+                    .stream(requireStream(streamId)).retain());
             // We return the bytes in consumeBytes() once the stream channel consumed the bytes.
             return 0;
         }
@@ -598,9 +638,10 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
         }
 
         @Override
-        public void onPriorityRead(
-                ChannelHandlerContext ctx, int streamId, int streamDependency, short weight, boolean exclusive) {
-            // TODO: Maybe handle me
+        public void onPriorityRead(ChannelHandlerContext ctx, int streamId, int streamDependency,
+                                   short weight, boolean exclusive) {
+            onHttp2Frame(ctx, new DefaultHttp2PriorityFrame(streamDependency, weight, exclusive)
+                    .stream(requireStream(streamId)));
         }
 
         @Override
@@ -609,9 +650,12 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
         }
 
         @Override
-        public void onPushPromiseRead(
-                ChannelHandlerContext ctx, int streamId, int promisedStreamId, Http2Headers headers, int padding)  {
-            // TODO: Maybe handle me
+        public void onPushPromiseRead(ChannelHandlerContext ctx, int streamId, int promisedStreamId,
+                                      Http2Headers headers, int padding) {
+            onHttp2Frame(ctx, new DefaultHttp2PushPromiseFrame(headers, padding, promisedStreamId)
+                    .pushStream(new DefaultHttp2FrameStream()
+                            .setStreamAndProperty(streamKey, connection().stream(promisedStreamId)))
+                    .stream(requireStream(streamId)));
         }
 
         private Http2FrameStream requireStream(int streamId) {
@@ -628,7 +672,7 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
     }
 
     private void onHttp2StreamWritabilityChanged(ChannelHandlerContext ctx, DefaultHttp2FrameStream stream,
-                                         @SuppressWarnings("unused") boolean writable) {
+                                                 @SuppressWarnings("unused") boolean writable) {
         ctx.fireUserEventTriggered(stream.writabilityChanged);
     }
 

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2PriorityFrame.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2020 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http2;
+
+import io.netty.util.internal.UnstableApi;
+
+/**
+ * HTTP/2 Priority Frame
+ */
+@UnstableApi
+public interface Http2PriorityFrame extends Http2StreamFrame {
+
+    /**
+     * Parent Stream Id of this Priority request
+     */
+    int streamDependency();
+
+    /**
+     * Stream weight
+     */
+    short weight();
+
+    /**
+     * Set to {@code true} if this stream is exclusive else set to {@code false}
+     */
+    boolean exclusive();
+
+    @Override
+    Http2PriorityFrame stream(Http2FrameStream stream);
+
+}

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2PushPromiseFrame.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http2;
+
+import io.netty.util.internal.UnstableApi;
+
+/**
+ * HTTP/2 Push Promise Frame
+ */
+@UnstableApi
+public interface Http2PushPromiseFrame extends Http2StreamFrame {
+
+    /**
+     * Set the Promise {@link Http2FrameStream} object for this frame.
+     */
+    Http2StreamFrame pushStream(Http2FrameStream stream);
+
+    /**
+     * Returns the Promise {@link Http2FrameStream} object for this frame, or {@code null} if the
+     * frame has yet to be associated with a stream.
+     */
+    Http2FrameStream pushStream();
+
+    /**
+     * {@link Http2Headers} sent in Push Promise
+     */
+    Http2Headers http2Headers();
+
+    /**
+     * Frame padding to use. Will be non-negative and less than 256.
+     */
+    int padding();
+
+    /**
+     * Promised Stream ID
+     */
+    int promisedStreamId();
+
+    @Override
+    Http2PushPromiseFrame stream(Http2FrameStream stream);
+
+}

codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2PushPromiseFrameTest.java

@@ -0,0 +1,242 @@
+/*
+ * Copyright 2020 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http2;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.bootstrap.ServerBootstrap;
+import io.netty.buffer.Unpooled;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInitializer;
+import io.netty.channel.ChannelPipeline;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.channel.socket.nio.NioServerSocketChannel;
+import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.util.CharsetUtil;
+import io.netty.util.ReferenceCountUtil;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static org.junit.Assert.assertEquals;
+
+public class DefaultHttp2PushPromiseFrameTest {
+
+    private final EventLoopGroup eventLoopGroup = new NioEventLoopGroup(2);
+    private final ClientHandler clientHandler = new ClientHandler();
+    private final Map<Integer, String> contentMap = new ConcurrentHashMap<Integer, String>();
+
+    private ChannelFuture connectionFuture;
+
+    @Before
+    public void setup() throws InterruptedException {
+        ServerBootstrap serverBootstrap = new ServerBootstrap()
+                .group(eventLoopGroup)
+                .channel(NioServerSocketChannel.class)
+                .childHandler(new ChannelInitializer<SocketChannel>() {
+                    @Override
+                    protected void initChannel(SocketChannel ch) {
+                        ChannelPipeline pipeline = ch.pipeline();
+
+                        Http2FrameCodec frameCodec = Http2FrameCodecBuilder.forServer()
+                                .autoAckSettingsFrame(true)
+                                .autoAckPingFrame(true)
+                                .build();
+
+                        pipeline.addLast(frameCodec);
+                        pipeline.addLast(new ServerHandler());
+                    }
+                });
+
+        ChannelFuture channelFuture = serverBootstrap.bind(0).sync();
+
+        final Bootstrap bootstrap = new Bootstrap()
+                .group(eventLoopGroup)
+                .channel(NioSocketChannel.class)
+                .handler(new ChannelInitializer<SocketChannel>() {
+                    @Override
+                    protected void initChannel(SocketChannel ch) {
+                        ChannelPipeline pipeline = ch.pipeline();
+
+                        Http2FrameCodec frameCodec = Http2FrameCodecBuilder.forClient()
+                                .autoAckSettingsFrame(true)
+                                .autoAckPingFrame(true)
+                                .initialSettings(Http2Settings.defaultSettings().pushEnabled(true))
+                                .build();
+
+                        pipeline.addLast(frameCodec);
+                        pipeline.addLast(clientHandler);
+                    }
+                });
+
+        connectionFuture = bootstrap.connect(channelFuture.channel().localAddress());
+    }
+
+    @Test
+    public void send() {
+        connectionFuture.addListener(new ChannelFutureListener() {
+            @Override
+            public void operationComplete(ChannelFuture future) {
+                clientHandler.write();
+            }
+        });
+    }
+
+    @After
+    public void shutdown() {
+        eventLoopGroup.shutdownGracefully();
+    }
+
+    private final class ServerHandler extends Http2ChannelDuplexHandler {
+
+        @Override
+        public void channelRead(final ChannelHandlerContext ctx, Object msg) throws Exception {
+
+            if (msg instanceof Http2HeadersFrame) {
+                final Http2HeadersFrame receivedFrame = (Http2HeadersFrame) msg;
+
+                Http2Headers pushRequestHeaders = new DefaultHttp2Headers();
+                pushRequestHeaders.path("/meow")
+                        .method("GET")
+                        .scheme("https")
+                        .authority("localhost:5555");
+
+                // Write PUSH_PROMISE request headers
+                final Http2FrameStream newPushFrameStream = newStream();
+                Http2PushPromiseFrame pushPromiseFrame = new DefaultHttp2PushPromiseFrame(pushRequestHeaders);
+                pushPromiseFrame.stream(receivedFrame.stream());
+                pushPromiseFrame.pushStream(newPushFrameStream);
+                ctx.writeAndFlush(pushPromiseFrame).addListener(new ChannelFutureListener() {
+                    @Override
+                    public void operationComplete(ChannelFuture future) {
+                        contentMap.put(newPushFrameStream.id(), "Meow, I am Pushed via HTTP/2");
+
+                        // Write headers for actual request
+                        Http2Headers http2Headers = new DefaultHttp2Headers();
+                        http2Headers.status("200");
+                        http2Headers.add("push", "false");
+                        Http2HeadersFrame headersFrame = new DefaultHttp2HeadersFrame(http2Headers, false);
+                        headersFrame.stream(receivedFrame.stream());
+                        ChannelFuture channelFuture = ctx.writeAndFlush(headersFrame);
+
+                        // Write Data of actual request
+                        channelFuture.addListener(new ChannelFutureListener() {
+                            @Override
+                            public void operationComplete(ChannelFuture future) throws Exception {
+                                Http2DataFrame dataFrame = new DefaultHttp2DataFrame(
+                                        Unpooled.wrappedBuffer("Meow".getBytes()), true);
+                                dataFrame.stream(receivedFrame.stream());
+                                ctx.writeAndFlush(dataFrame);
+                            }
+                        });
+                    }
+                });
+            } else if (msg instanceof Http2PriorityFrame) {
+                Http2PriorityFrame priorityFrame = (Http2PriorityFrame) msg;
+                String content = contentMap.get(priorityFrame.stream().id());
+                if (content == null) {
+                    ctx.writeAndFlush(new DefaultHttp2GoAwayFrame(Http2Error.REFUSED_STREAM));
+                    return;
+                }
+
+                // Write headers for Priority request
+                Http2Headers http2Headers = new DefaultHttp2Headers();
+                http2Headers.status("200");
+                http2Headers.add("push", "true");
+                Http2HeadersFrame headersFrame = new DefaultHttp2HeadersFrame(http2Headers, false);
+                headersFrame.stream(priorityFrame.stream());
+                ctx.writeAndFlush(headersFrame);
+
+                // Write Data of Priority request
+                Http2DataFrame dataFrame = new DefaultHttp2DataFrame(Unpooled.wrappedBuffer(content.getBytes()), true);
+                dataFrame.stream(priorityFrame.stream());
+                ctx.writeAndFlush(dataFrame);
+            }
+        }
+    }
+
+    private static final class ClientHandler extends Http2ChannelDuplexHandler {
+
+        private ChannelHandlerContext ctx;
+
+        @Override
+        public void channelActive(ChannelHandlerContext ctx) throws InterruptedException {
+            this.ctx = ctx;
+        }
+
+        void write() {
+            Http2Headers http2Headers = new DefaultHttp2Headers();
+            http2Headers.path("/")
+                    .authority("localhost")
+                    .method("GET")
+                    .scheme("https");
+
+            Http2HeadersFrame headersFrame = new DefaultHttp2HeadersFrame(http2Headers, true);
+            headersFrame.stream(newStream());
+            ctx.writeAndFlush(headersFrame);
+        }
+
+        @Override
+        public void channelRead(ChannelHandlerContext ctx, Object msg) {
+
+            if (msg instanceof Http2PushPromiseFrame) {
+                Http2PushPromiseFrame pushPromiseFrame = (Http2PushPromiseFrame) msg;
+
+                assertEquals("/meow", pushPromiseFrame.http2Headers().path().toString());
+                assertEquals("GET", pushPromiseFrame.http2Headers().method().toString());
+                assertEquals("https", pushPromiseFrame.http2Headers().scheme().toString());
+                assertEquals("localhost:5555", pushPromiseFrame.http2Headers().authority().toString());
+
+                Http2PriorityFrame priorityFrame = new DefaultHttp2PriorityFrame(pushPromiseFrame.stream().id(),
+                        Http2CodecUtil.DEFAULT_PRIORITY_WEIGHT, true);
+                priorityFrame.stream(pushPromiseFrame.pushStream());
+                ctx.writeAndFlush(priorityFrame);
+            } else if (msg instanceof Http2HeadersFrame) {
+                Http2HeadersFrame headersFrame = (Http2HeadersFrame) msg;
+
+                if (headersFrame.stream().id() == 3) {
+                    assertEquals("200", headersFrame.headers().status().toString());
+                    assertEquals("false", headersFrame.headers().get("push").toString());
+                } else if (headersFrame.stream().id() == 2) {
+                    assertEquals("200", headersFrame.headers().status().toString());
+                    assertEquals("true", headersFrame.headers().get("push").toString());
+                } else {
+                    ctx.writeAndFlush(new DefaultHttp2GoAwayFrame(Http2Error.REFUSED_STREAM));
+                }
+            } else if (msg instanceof Http2DataFrame) {
+                Http2DataFrame dataFrame = (Http2DataFrame) msg;
+
+                try {
+                    if (dataFrame.stream().id() == 3) {
+                        assertEquals("Meow", dataFrame.content().toString(CharsetUtil.UTF_8));
+                    } else if (dataFrame.stream().id() == 2) {
+                        assertEquals("Meow, I am Pushed via HTTP/2", dataFrame.content().toString(CharsetUtil.UTF_8));
+                    } else {
+                        ctx.writeAndFlush(new DefaultHttp2GoAwayFrame(Http2Error.REFUSED_STREAM));
+                    }
+                } finally {
+                    ReferenceCountUtil.release(dataFrame);
+                }
+            }
+        }
+    }
+}