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/hosts/README.md

@@ -16,12 +16,12 @@ available hosts files that block access to advertising servers.
 ~~~
 hosts [FILE [ZONES...]] {
     [INLINE]
-    fallthrough
+    fallthrough [ZONES...]
 }
 ~~~
 
 * **FILE** the hosts file to read and parse. If the path is relative the path from the *root*
-  directive will be prepended to it. Defaults to /etc/hosts if omitted. We scan the file for changes 
+  directive will be prepended to it. Defaults to /etc/hosts if omitted. We scan the file for changes
   every 5 seconds.
 * **ZONES** zones it should be authoritative for. If empty, the zones from the configuration block
    are used.
@@ -29,6 +29,9 @@ hosts [FILE [ZONES...]] {
    then all of them will be treated as the additional content for hosts file. The specified hosts
    file path will still be read but entries will be overrided.
 * `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.
 
 ## Examples
 

plugin/hosts/hosts.go

@@ -7,6 +7,7 @@ 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"
 )
@@ -16,7 +17,7 @@ type Hosts struct {
 	Next plugin.Handler
 	*Hostsfile
 
-	Fallthrough bool
+	Fall *fall.F
 }
 
 // ServeDNS implements the plugin.Handle interface.
@@ -52,7 +53,7 @@ func (h Hosts) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
 	}
 
 	if len(answers) == 0 {
-		if h.Fallthrough {
+		if h.Fall.Through(qname) {
 			return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
 		}
 		if !h.otherRecordsExist(state.QType(), qname) {

plugin/hosts/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"
 )
@@ -105,14 +106,10 @@ func hostsParse(c *caddy.Controller) (Hosts, error) {
 		for c.NextBlock() {
 			switch c.Val() {
 			case "fallthrough":
-				args := c.RemainingArgs()
-				if len(args) == 0 {
-					h.Fallthrough = true
-					continue
-				}
-				return h, c.ArgErr()
+				h.Fall = fall.New()
+				h.Fall.SetZones(c.RemainingArgs())
 			default:
-				if !h.Fallthrough {
+				if h.Fall.IsNil() {
 					line := strings.Join(append([]string{c.Val()}, c.RemainingArgs()...), " ")
 					inline = append(inline, line)
 					continue

plugin/hosts/setup_test.go

@@ -3,6 +3,8 @@ package hosts
 import (
 	"testing"
 
+	"github.com/coredns/coredns/plugin/pkg/fall"
+
 	"github.com/mholt/caddy"
 )
 
@@ -12,48 +14,48 @@ func TestHostsParse(t *testing.T) {
 		shouldErr           bool
 		expectedPath        string
 		expectedOrigins     []string
-		expectedFallthrough bool
+		expectedFallthrough *fall.F
 	}{
 		{
 			`hosts
 `,
-			false, "/etc/hosts", nil, false,
+			false, "/etc/hosts", nil, nil,
 		},
 		{
 			`hosts /tmp`,
-			false, "/tmp", nil, false,
+			false, "/tmp", nil, nil,
 		},
 		{
 			`hosts /etc/hosts miek.nl.`,
-			false, "/etc/hosts", []string{"miek.nl."}, false,
+			false, "/etc/hosts", []string{"miek.nl."}, nil,
 		},
 		{
 			`hosts /etc/hosts miek.nl. pun.gent.`,
-			false, "/etc/hosts", []string{"miek.nl.", "pun.gent."}, false,
+			false, "/etc/hosts", []string{"miek.nl.", "pun.gent."}, nil,
 		},
 		{
 			`hosts {
 				fallthrough
 			}`,
-			false, "/etc/hosts", nil, true,
+			false, "/etc/hosts", nil, fall.Zero(),
 		},
 		{
 			`hosts /tmp {
 				fallthrough
 			}`,
-			false, "/tmp", nil, true,
+			false, "/tmp", nil, fall.Zero(),
 		},
 		{
 			`hosts /etc/hosts miek.nl. {
 				fallthrough
 			}`,
-			false, "/etc/hosts", []string{"miek.nl."}, true,
+			false, "/etc/hosts", []string{"miek.nl."}, fall.Zero(),
 		},
 		{
 			`hosts /etc/hosts miek.nl 10.0.0.9/8 {
 				fallthrough
 			}`,
-			false, "/etc/hosts", []string{"miek.nl.", "10.in-addr.arpa."}, true,
+			false, "/etc/hosts", []string{"miek.nl.", "10.in-addr.arpa."}, fall.Zero(),
 		},
 	}
 
@@ -70,8 +72,8 @@ func TestHostsParse(t *testing.T) {
 				t.Fatalf("Test %d expected %v, got %v", i, test.expectedPath, h.path)
 			}
 		} else {
-			if h.Fallthrough != test.expectedFallthrough {
-				t.Fatalf("Test %d expected fallthrough of %v, got %v", i, test.expectedFallthrough, h.Fallthrough)
+			if !h.Fall.Equal(test.expectedFallthrough) {
+				t.Fatalf("Test %d expected fallthrough of %v, got %v", i, test.expectedFallthrough, h.Fall)
 			}
 			if len(h.Origins) != len(test.expectedOrigins) {
 				t.Fatalf("Test %d expected %v, got %v", i, test.expectedOrigins, h.Origins)
@@ -90,7 +92,7 @@ func TestHostsInlineParse(t *testing.T) {
 		inputFileRules      string
 		shouldErr           bool
 		expectedbyAddr      map[string][]string
-		expectedFallthrough bool
+		expectedFallthrough *fall.F
 	}{
 		{
 			`hosts highly_unlikely_to_exist_hosts_file example.org {
@@ -103,28 +105,28 @@ func TestHostsInlineParse(t *testing.T) {
 					`example.org.`,
 				},
 			},
-			true,
+			fall.Zero(),
 		},
 		{
 			`hosts highly_unlikely_to_exist_hosts_file example.org {
-                                10.0.0.1 example.org
-                        }`,
+			                                10.0.0.1 example.org
+			                        }`,
 			false,
 			map[string][]string{
 				`10.0.0.1`: {
 					`example.org.`,
 				},
 			},
-			false,
+			nil,
 		},
 		{
 			`hosts highly_unlikely_to_exist_hosts_file example.org {
-                                fallthrough
-                                10.0.0.1 example.org
-                        }`,
+			                                fallthrough
+			                                10.0.0.1 example.org
+			                        }`,
 			true,
 			map[string][]string{},
-			true,
+			fall.Zero(),
 		},
 	}
 
@@ -137,8 +139,8 @@ func TestHostsInlineParse(t *testing.T) {
 		} else if err != nil && !test.shouldErr {
 			t.Fatalf("Test %d expected no errors, but got '%v'", i, err)
 		} else if !test.shouldErr {
-			if h.Fallthrough != test.expectedFallthrough {
-				t.Fatalf("Test %d expected fallthrough of %v, got %v", i, test.expectedFallthrough, h.Fallthrough)
+			if !h.Fall.Equal(test.expectedFallthrough) {
+				t.Fatalf("Test %d expected fallthrough of %v, got %v", i, test.expectedFallthrough, h.Fall)
 			}
 			for k, expectedVal := range test.expectedbyAddr {
 				if val, ok := h.hmap.byAddr[k]; !ok {