* fix case preservation and add test
* only fix case in k8s

This fix will error out when multiple https endpoints are specified,
as additional work is needed to support beyond http.

This fix fixes 1464.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Almost 100% mechanical change, except the fact that import/import.md
is moved to import/README.md

No content changes.
Signed-off-by: Miek Gieben <miek@miek.nl>

* wip: add import to make it have docs

Fake the import plugin further to give it proper docs. This should help
make it more discoverable.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Finish writing the documentation
Signed-off-by: Miek Gieben <miek@miek.nl>

Add words in object.go on the memory use and put some future ideas in
there to use even less (if we have to at some point).
Signed-off-by: Miek Gieben <miek@miek.nl>

* plugin/log: update nodata/NXDOMAIN story a bit

Add more words on nodata and NXDOMAIN which is a confusing DNS
"feature"

Fixes: #2412
Signed-off-by: Miek Gieben <miek@miek.nl>

* typos
Signed-off-by: Miek Gieben <miek@miek.nl>

* update zplugin.go path && add .PHONY for all target

* update zplugin.go path && add .PHONY for all target

* update zplugin.go target

New release, kick of tests.
Signed-off-by: Miek Gieben <miek@miek.nl>

These can be used (and are handy), document them.
Signed-off-by: Miek Gieben <miek@miek.nl>

Add some docs in the manual page. Problem here is that it is only in the
manual page and we don't publish this particular one on coredns.io.
Signed-off-by: Miek Gieben <miek@miek.nl>

* disable ra flag for several plugins

* removed unnecessary assignment

* removed more unnecessary assignments

* Add more fuzzing
Signed-off-by: Miek Gieben <miek@miek.nl>

* More fuzzing targets
Signed-off-by: Miek Gieben <miek@miek.nl>

* Fuzzing: add more fuzzing targets

Also add Corefile fuzzing.
Signed-off-by: Miek Gieben <miek@miek.nl>

Missed this before the release. Add the manpage.
Signed-off-by: Miek Gieben <miek@miek.nl>

Show from and to address when detecting a loop they may aid in
debugging.

Hard to create a unit test, but this is a startup run with self induced
loop:

~~~ corefile
.:1053 {
    loop
    log
    forward . 127.0.0.1:1053
}
~~~~

~~~
:1053
2018-12-16T10:11:03.695Z [INFO] CoreDNS-1.3.0
2018-12-16T10:11:03.695Z [INFO] linux/amd64, go1.11,
CoreDNS-1.3.0
linux/amd64, go1.11,
2018-12-16T10:11:03.696Z [FATAL] plugin/loop: Loop (127.0.0.1:51384 -> :1053) detected for zone ".", see https://coredns.io/plugins/loop#troubleshooting. Query: "HINFO 2781022615773629442.4133547885299871809."
~~~

Update the docs and polished that a bit as well.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Update client-go to v10.0.0 (Kubernetes 1.13)

This fix updates client-go to v10.0.0 which matches
Kubernetes 1.13 (released several days ago).

Other changes in Gopkg.yaml:
- Updated apimachinary, api, klog, yaml associated with k8s version
  go dep will not automatically match the version.
- Added [prune] field (otherwise go dep will not prune automatically)
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Updated Gopkg.lock
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Updated vendor for client-go v10.0.0
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Signed-off-by: Miek Gieben <miek@miek.nl>

* Add new plugin: external

This plugin works in conjunction with the kubernetes plugin and exports
ingress and LB addresses as DNS records. It bypasses backend.go and
backend_lookup.go flow because it is not needed.

README, tests are implemented. The tests only exercise the unit tests,
this has not been tested in any ci.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Rename to k8s_external
Signed-off-by: Miek Gieben <miek@miek.nl>

* go gen
Signed-off-by: Miek Gieben <miek@miek.nl>

update the manpages by running make -f Makefile.doc

No other changes.
Signed-off-by: Miek Gieben <miek@miek.nl>

The miekg/dns API is a bit scruffy (documentation PR in flight soon),
but these both need to be set for the correct RCODE to be reflected in
the returned packet.
Signed-off-by: Miek Gieben <miek@miek.nl>

* core: edns0 tweaks

Per comment thread in https://github.com/coredns/coredns/pull/2357 which
spotted a bug; updated the code and added some comments.

This function should probably be redone as some point or made obsolete.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Remove setting options when m is EDNS0 record

Assume upstream set them correctly or a plugin.
Signed-off-by: Miek Gieben <miek@miek.nl>

This clear out the remaining map[x]bool usage and moves the bool to an
empty struct.

Two note worthy other changes:

* EnableChaos in the server is now also exported to make it show up in
  the documentation.
* The auto plugin is left as is, because there the boolean is
  explicitaly set to false to signal 'to-be-deleted' and the key is left
  as-is.
Signed-off-by: Miek Gieben <miek@miek.nl>

Automatically submitted.

* plugin/kubernetes: smaller map

to continue with a theme: the map[string]bool can be reduced
to map[string]struct{} to reduce a tiny amount of memory.
Signed-off-by: Miek Gieben <miek@miek.nl>

* fix tests
Signed-off-by: Miek Gieben <miek@miek.nl>

This fix converts bool map to struct{} map in etcd.go
(there might be several other places).
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

This is a relic from the etcd integration and only used to remove in the
final answer returned to the client. We do need it. Make it a constant
and only one character wide.
Signed-off-by: Miek Gieben <miek@miek.nl>

These maps where all map[x]bool. Change this a map[x]struct{} as this
is smaller and we only use these map to signal "this element exists".

This should preserve a (small) amount of memory.
Signed-off-by: Miek Gieben <miek@miek.nl>

Make the NewSRV and friends slightly smarter. Optimize the calling of
targetStrip which is almost certainly not used.

Added benchmark show a modest improvement:

benchmark             old ns/op     new ns/op     delta
BenchmarkNewSRV-4     300           283           -5.67%
Signed-off-by: Miek Gieben <miek@miek.nl>

* Fix EDNS0 compliance

Do SizeAndDo in the server (ScrubWriter) and remove all uses of this
from the plugins. Also *always* do it. This is to get into compliance
for https://dnsflagday.net/.

The pkg/edns0 now exports the EDNS0 options we understand; this is
exported to allow plugins add things there. The *rewrite* plugin used
this to add custom EDNS0 option codes that the server needs to
understand.

This also needs a new release of miekg/dns because it triggered a
race-condition that was basicly there forever.

See:
* https://github.com/miekg/dns/issues/857
* https://github.com/miekg/dns/pull/859

Running a test instance and pointing the https://ednscomp.isc.org/ednscomp
to it shows the tests are now fixed:

~~~
EDNS Compliance Tester
Checking: 'miek.nl' as at 2018-12-01T17:53:15Z

miek.nl. @147.75.204.203 (drone.coredns.io.): dns=ok edns=ok edns1=ok edns@512=ok ednsopt=ok edns1opt=ok do=ok ednsflags=ok docookie=ok edns512tcp=ok optlist=ok
miek.nl. @2604:1380:2002:a000::1 (drone.coredns.io.): dns=ok edns=ok edns1=ok edns@512=ok ednsopt=ok edns1opt=ok do=ok ednsflags=ok docookie=ok edns512tcp=ok optlist=ok

All Ok
Codes
ok - test passed.
~~~
Signed-off-by: Miek Gieben <miek@miek.nl>
Signed-off-by: Miek Gieben <miek@miek.nl>

* typos in comments
Signed-off-by: Miek Gieben <miek@miek.nl>

Automatically submitted.

Automatically submitted.

* improve loop troubleshoot docs

* fix spelling

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

I think this is causing problem and it will actually clash with the
scrubbing that now happens for all plugins anyway. We're assuming the
returned message will be valid even with tc being set. request.Scrub
follows that same logic.
Signed-off-by: Miek Gieben <miek@miek.nl>

* pkg/up: implement backoff

Every 2nd failure we double the interval until we hit 4 * interval. This
to have some sort of backoff, esp when a large cluster of coredns shares
an upstream (original intent of up package) they will hammer the
upstream. This put some back pressure on that.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Update plugin/pkg/up/up.go
Co-Authored-By: miekg <miek@miek.nl>