middleware/file: Support delegations (#124)

Return a delegation when seeing one while traversing the tree in
search of an answer.

Put the SOA and NS record in the zone.Apex as these are to be handled
somewhat special.

Lowercase record on insert to make compares easier. This lowercases
all RR that have domain names in their rdata as well.

1 files changed, 106 insertions, 0 deletions

diff --git a/middleware/file/delegation_test.go b/middleware/file/delegation_test.go
new file mode 100644
index 000000000..d7286a3bd
--- /dev/null
+++ b/middleware/file/delegation_test.go
@@ -0,0 +1,106 @@
+package file
+
+import (
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/test"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+var delegationTestCases = []test.Case{
+	{
+		Qname: "a.delegated.miek.nl.", Qtype: dns.TypeTXT,
+		Ns: []dns.RR{
+			test.NS("delegated.miek.nl.	1800	IN	NS	a.delegated.miek.nl."),
+			test.NS("delegated.miek.nl.	1800	IN	NS	ns-ext.nlnetlabs.nl."),
+		},
+		Extra: []dns.RR{
+			test.A("a.delegated.miek.nl. 1800 IN A 139.162.196.78"),
+			test.AAAA("a.delegated.miek.nl. 1800 IN AAAA 2a01:7e00::f03c:91ff:fef1:6735"),
+		},
+	},
+	{
+		Qname: "delegated.miek.nl.", Qtype: dns.TypeNS,
+		Answer: []dns.RR{
+			test.NS("delegated.miek.nl.	1800	IN	NS	a.delegated.miek.nl."),
+			test.NS("delegated.miek.nl.	1800	IN	NS	ns-ext.nlnetlabs.nl."),
+		},
+	},
+}
+
+func TestLookupDelegation(t *testing.T) {
+	zone, err := Parse(strings.NewReader(dbMiekNL_delegation), testzone, "stdin")
+	if err != nil {
+		t.Fatalf("expect no error when reading zone, got %q", err)
+	}
+
+	fm := File{Next: test.ErrorHandler(), Zones: Zones{Z: map[string]*Zone{testzone: zone}, Names: []string{testzone}}}
+	ctx := context.TODO()
+
+	for _, tc := range delegationTestCases {
+		m := tc.Msg()
+
+		rec := middleware.NewResponseRecorder(&test.ResponseWriter{})
+		_, err := fm.ServeDNS(ctx, rec, m)
+		if err != nil {
+			t.Errorf("expected no error, got %v\n", err)
+			return
+		}
+		resp := rec.Msg()
+
+		sort.Sort(test.RRSet(resp.Answer))
+		sort.Sort(test.RRSet(resp.Ns))
+		sort.Sort(test.RRSet(resp.Extra))
+
+		if !test.Header(t, tc, resp) {
+			t.Logf("%v\n", resp)
+			continue
+		}
+		if !test.Section(t, tc, test.Answer, resp.Answer) {
+			t.Logf("%v\n", resp)
+		}
+		if !test.Section(t, tc, test.Ns, resp.Ns) {
+			t.Logf("%v\n", resp)
+		}
+		if !test.Section(t, tc, test.Extra, resp.Extra) {
+			t.Logf("%v\n", resp)
+		}
+	}
+}
+
+const dbMiekNL_delegation = `
+$TTL    30M
+$ORIGIN miek.nl.
+@       IN      SOA     linode.atoom.net. miek.miek.nl. (
+                             1282630057 ; Serial
+                             4H         ; Refresh
+                             1H         ; Retry
+                             7D         ; Expire
+                             4H )       ; Negative Cache TTL
+                IN      NS      linode.atoom.net.
+                IN      NS      ns-ext.nlnetlabs.nl.
+                IN      NS      omval.tednet.nl.
+                IN      NS      ext.ns.whyscream.net.
+
+                IN      MX      1  aspmx.l.google.com.
+                IN      MX      5  alt1.aspmx.l.google.com.
+                IN      MX      5  alt2.aspmx.l.google.com.
+                IN      MX      10 aspmx2.googlemail.com.
+                IN      MX      10 aspmx3.googlemail.com.
+
+delegated	IN	NS      a.delegated
+		IN	NS      ns-ext.nlnetlabs.nl.
+
+a.delegated     IN      TXT     "obscured"
+                IN      A       139.162.196.78
+                IN      AAAA    2a01:7e00::f03c:91ff:fef1:6735
+
+a               IN      A       139.162.196.78
+                IN      AAAA    2a01:7e00::f03c:91ff:fef1:6735
+www             IN      CNAME   a
+archive         IN      CNAME   a`