Add pkg/fall for Fallthrough (#1355)

* Add pkg/fall for Fallthrough

Move this into it's own package to facilitate tests. Important bug
was fixed: make the names fully qualified.

Add fall package to hosts, reverse, etcd, and fix kubernetes and any
tests. The k8s tests are still as-is, might need a future cleanup.

plugin/reverse/README.md

@@ -15,7 +15,7 @@ response. This is only done for "address" records (PTR, A and AAAA).
 reverse NETWORK... {
     hostname TEMPLATE
     [ttl TTL]
-    [fallthrough]
+    [fallthrough [ZONES...]]
     [wildcard]
 ~~~
 
@@ -23,6 +23,9 @@ reverse NETWORK... {
 * `hostname` injects the IP and zone to a template for the hostname. Defaults to "ip-{IP}.{zone[1]}". See below for template.
 * `ttl` defaults to 60
 * `fallthrough` if zone matches and no record can be generated, pass request to the next plugin.
+  If **[ZONES...]** is omitted, then fallthrough happens for all zones for which the plugin
+  is authoritative. If specific zones are listed (for example `in-addr.arpa` and `ip6.arpa`), then only
+  queries for those zones will be subject to fallthrough.
 * `wildcard` allows matches to catch all subdomains as well.
 
 ### Template Syntax

plugin/reverse/reverse.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/pkg/dnsutil"
+	"github.com/coredns/coredns/plugin/pkg/fall"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -13,9 +14,10 @@ import (
 
 // Reverse provides dynamic reverse DNS and the related forward RR.
 type Reverse struct {
-	Next        plugin.Handler
-	Networks    networks
-	Fallthrough bool
+	Next     plugin.Handler
+	Networks networks
+
+	Fall *fall.F
 }
 
 // ServeDNS implements the plugin.Handler interface.
@@ -97,7 +99,7 @@ func (re Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 		return dns.RcodeSuccess, nil
 	}
 
-	if re.Fallthrough {
+	if re.Fall.Through(state.Name()) {
 		return plugin.NextOrFailure(re.Name(), re.Next, ctx, w, r)
 	}
 	return dns.RcodeServerFailure, nil

plugin/reverse/reverse_test.go

@@ -24,7 +24,6 @@ func TestReverse(t *testing.T) {
 			Template:     "ip-{ip}.example.org.",
 			RegexMatchIP: regexIP4,
 		}},
-		Fallthrough: false,
 	}
 
 	tests := []struct {

plugin/reverse/setup.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/pkg/fall"
 
 	"github.com/mholt/caddy"
 )
@@ -21,19 +22,19 @@ func init() {
 }
 
 func setupReverse(c *caddy.Controller) error {
-	networks, fallThrough, err := reverseParse(c)
+	networks, fall, err := reverseParse(c)
 	if err != nil {
 		return plugin.Error("reverse", err)
 	}
 
 	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
-		return Reverse{Next: next, Networks: networks, Fallthrough: fallThrough}
+		return Reverse{Next: next, Networks: networks, Fall: fall}
 	})
 
 	return nil
 }
 
-func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
+func reverseParse(c *caddy.Controller) (nets networks, f *fall.F, err error) {
 	zones := make([]string, len(c.ServerBlockKeys))
 	wildcard := false
 
@@ -52,12 +53,12 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 			}
 			_, ipnet, err := net.ParseCIDR(cidr)
 			if err != nil {
-				return nil, false, c.Errf("network needs to be CIDR formatted: %q\n", cidr)
+				return nil, f, c.Errf("network needs to be CIDR formatted: %q\n", cidr)
 			}
 			cidrs = append(cidrs, ipnet)
 		}
 		if len(cidrs) == 0 {
-			return nil, false, c.ArgErr()
+			return nil, f, c.ArgErr()
 		}
 
 		// set defaults
@@ -69,27 +70,28 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 			switch c.Val() {
 			case "hostname":
 				if !c.NextArg() {
-					return nil, false, c.ArgErr()
+					return nil, f, c.ArgErr()
 				}
 				template = c.Val()
 
 			case "ttl":
 				if !c.NextArg() {
-					return nil, false, c.ArgErr()
+					return nil, f, c.ArgErr()
 				}
 				ttl, err = strconv.Atoi(c.Val())
 				if err != nil {
-					return nil, false, err
+					return nil, f, err
 				}
 
 			case "wildcard":
 				wildcard = true
 
 			case "fallthrough":
-				fall = true
+				f = fall.New()
+				f.SetZones(c.RemainingArgs())
 
 			default:
-				return nil, false, c.ArgErr()
+				return nil, f, c.ArgErr()
 			}
 		}
 
@@ -107,7 +109,7 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 		// extract zone from template
 		templateZone := strings.SplitAfterN(template, ".", 2)
 		if len(templateZone) != 2 || templateZone[1] == "" {
-			return nil, false, c.Errf("cannot find domain in template '%v'", template)
+			return nil, f, c.Errf("cannot find domain in template '%v'", template)
 		}
 
 		// Create for each configured network in this stanza
@@ -128,7 +130,7 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 					regexIP,
 					1) + "$")
 			if err != nil {
-				return nil, false, err
+				return nil, f, err
 			}
 
 			nets = append(nets, network{
@@ -143,5 +145,5 @@ func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
 
 	// sort by cidr
 	sort.Sort(nets)
-	return nets, fall, nil
+	return nets, f, nil
 }