This fix adds unit tests for `ExtractAddressFromReverse`. It also
updates the implementation of `ExtractAddressFromReverse` so that
only a valid IPv4 or IPv6 address (in string format) is returned.
If the addresses is not valid and can not be handled by golang's
`net.ParseIP` then an empty string (`""`) will be returned.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Move all (almost all) Go files in middleware into their
own packages. This makes for better naming and discoverability.
Lot of changes elsewhere to make this change.
The middleware.State was renamed to request.Request which is better,
but still does not cover all use-cases. It was also moved out middleware
because it is used by `dnsserver` as well.
A pkg/dnsutil packages was added for shared, handy, dns util functions.
All normalize functions are now put in normalize.go
