net: use the extended RCode from EDNS(0) OPT resources
For a while now we support EDNS, but the current
implementation only sends the OPT resource and doesn't
do anything with the response OPT resource.
For reference the miekg/dns updates the RCode in the
header when there is a OPT resource:
https://github.com/miekg/dns/blob/
48f38ebef989eedc6b57f1869ae849ccc8f5fe29/msg.go#L868-L872
Change-Id: I0a7146aed3e50654f340a3925f48612561cb85f4
GitHub-Last-Rev:
adc304167e0540cb1f066f07a249d67fad89182e
GitHub-Pull-Request: golang/go#61695
Reviewed-on: https://go-review.googlesource.com/c/go/+/514835
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>