reverse zone: fix Normalize (#4621)

Make normalize return multiple "hosts" (= reverse zones) when a
non-octet boundary cidr is given.

Added pkg/cidr package that holds the cidr calculation routines; felt
they didn't really fit dnsutil.

This change means the IPNet return parameter isn't needed, the hosts are
all correct. The tests that tests this is also removed: TestSplitHostPortReverse
The fallout was that zoneAddr _also_ doesn't need the IPNet member, that
in turn make it visible that zoneAddr in address.go duplicated a bunch
of stuff from register.go; removed/refactored that too.

Created a plugin.OriginsFromArgsOrServerBlock to help plugins do the
right things, by consuming ZONE arguments; this now expands reverse
zones correctly. This is mostly mechanical.

Remove the reverse test in plugin/kubernetes which is a copy-paste from
a core test (which has since been fixed).

Remove MustNormalize as it has no plugin users.

This change is not backwards compatible to plugins that have a ZONE
argument that they parse in the setup util.

All in-tree plugins have been updated.

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

1 files changed, 0 insertions, 38 deletions

diff --git a/core/dnsserver/reverse.go b/core/dnsserver/reverse.go
deleted file mode 100644
index 2d0a7c740..000000000
--- a/core/dnsserver/reverse.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package dnsserver
-
-import (
-	"math"
-	"net"
-
-	"github.com/apparentlymart/go-cidr/cidr"
-)
-
-// classFromCIDR return slice of "classful" (/8, /16, /24 or /32 only) CIDR's from the CIDR in net.
-func classFromCIDR(n *net.IPNet) []string {
-	ones, _ := n.Mask.Size()
-	if ones%8 == 0 {
-		return []string{n.String()}
-	}
-
-	mask := int(math.Ceil(float64(ones)/8)) * 8
-	networks := subnets(n, mask)
-	cidrs := make([]string, len(networks))
-	for i := range networks {
-		cidrs[i] = networks[i].String()
-	}
-	return cidrs
-}
-
-// subnets return a slice of prefixes with the desired mask subnetted from original network.
-func subnets(network *net.IPNet, newPrefixLen int) []*net.IPNet {
-	prefixLen, _ := network.Mask.Size()
-	maxSubnets := int(math.Exp2(float64(newPrefixLen)) / math.Exp2(float64(prefixLen)))
-	nets := []*net.IPNet{{network.IP, net.CIDRMask(newPrefixLen, 8*len(network.IP))}}
-
-	for i := 1; i < maxSubnets; i++ {
-		next, _ := cidr.NextSubnet(nets[len(nets)-1], newPrefixLen)
-		nets = append(nets, next)
-	}
-
-	return nets
-}