RST_STREAM / GOAWAY opaque data

[mnot]

In Tokyo, there was discussion of whether it would be useful to allow opaque data in RST_STREAM and GOAWAY. Waiting for a full proposal.

[jasnell]

I believe the default for these ought to be not to include opaque data, however, a frame specific flag could be used to indicate additional data. e.g. add an ADDITIONAL_DATA (0x2) flag. If the flag is not set, additional data is ignored or treated like a protocol error.

[willchan]

I think it'd be useful to allow opaque data. I'm not going to bother fighting for my bike shed color, but if I were to pick, I'd just use the length field. I don't think a flag really gains us anything, except more cases in our code that need to be specified as ignored/error.

[mnot]

Discussed at SF Interim; will put into implementation draft but mark AT RISK. Hasan to help with text.