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>
* New plugin: loop
Add a plugin that detects loops. It does this by sending an unique query
to our selves. If we see the query more than twice we stop the process.
If there isn't a loop, the plugin disables it self and becomes a noop
plugin.
Signed-off-by: Miek Gieben <miek@miek.nl>
