Motivation:
When parsing HEADERS, connection errors can occur (e.g., too large of
headers, such that we don't want to HPACK decode them). These trigger a
GOAWAY with a last-stream-id telling the client which streams haven't
been processed.
Unfortunately that last-stream-id didn't include the stream for the
HEADERS that triggered the error. Since clients are free to silently
retry streams not included in last-stream-id, the client is free to
retransmit the request on a new connection, which will fail the
connection with the wrong last-stream-id, and the client is still free
to retransmit the request.
Modifications:
Have fatal connection errors (those that hard-cut the connection)
include all streams in last-stream-id, which guarantees the HEADERS'
stream is included and thus should not be silently retried by the HTTP/2
client.
This modification is heavy-handed, as it will cause racing streams to
also fail, but alternatives that provide precise last-stream-id tracking
are much more invasive. Hard-cutting the connection is already
heavy-handed and so is rare.
Result:
Fixes#10670
0754dac14d