DefaultHttp2ConnectionEncoder writeHeaders method always send an header frame with a priority

[vietj]

Expected behavior

The DefaultHttp2ConnectionEncoder sends an header frame without priority when the writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding, boolean endStream, ChannelPromise promise) method is used

Actual behavior

The current implementation delegates to writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency, short weight, boolean exclusive, int padding, boolean endStream, ChannelPromise promise) that will send an header frame with the priority flag set and the default priority values.

Steps to reproduce

Use DefaultHttp2ConnectionEncoder#writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding, boolean endStream, ChannelPromise promise) with an Http2FrameWriter, the frame writer will have the writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency, short weight, boolean exclusive, int padding, boolean endStream, ChannelPromise promise) called.

On the wire, this will encode a different headers frame with the priority flag set instead of being unset.

Minimal yet complete reproducer code (or URL to code)

I believe this in DefaultHttp2ConnectionEncoderTest should do the job

    @Test
    public void headersWithNoPriority() {
        writeAllFlowControlledFrames();
        final int streamId = 6;
        ChannelPromise promise = newPromise();
        encoder.writeHeaders(ctx, streamId, EmptyHttp2Headers.INSTANCE, 0, false, promise);
        verify(writer, times(1)).writeHeaders(eq(ctx), eq(streamId), eq(EmptyHttp2Headers.INSTANCE), eq(0), eq(false), eq(promise));
    }

This fails with

Argument(s) are different! Wanted:
writer.writeHeaders(
    ctx,
    6,
    EmptyHttp2Headers[],
    0,
    false,
    DefaultChannelPromise@2374d36a(success)
);
-> at io.netty.handler.codec.http2.DefaultHttp2ConnectionEncoderTest.headersWithNoPriority(DefaultHttp2ConnectionEncoderTest.java:403)
Actual invocation has different arguments:
writer.writeHeaders(
    ctx,
    6,
    EmptyHttp2Headers[],
    0,
    (short) 16,
    false,
    0,
    false,
    DefaultChannelPromise@2374d36a(success)
);
-> at io.netty.handler.codec.http2.DefaultHttp2ConnectionEncoder.writeHeaders(DefaultHttp2ConnectionEncoder.java:208)

Netty version

All of 4.1 branch

JVM version (e.g. java -version)

Does not matter

OS version (e.g. uname -a)

Does not matter

[vietj]

See also https://httpwg.org/specs/rfc7540.html#rfc.section.6.2

[normanmaurer]

@vietj sounds about right... interested in doing a PR ?

[vietj]

yes I will try soon.

[normanmaurer]

/cc @bryce-anderson @ejona86

[normanmaurer]

@vietj don't worry... working on it

[normanmaurer]

@vietj PTAL #9852