Cache (#126)

* Add middleware/cache

Add a caching middleware that caches nxdomain, nodata and successful
responses. It differentiates between DNSSEC on normal DNS replies.

Each reply is compress and scrubbed so it will fit the specific client
asking for it.

* first simple test, less exporting of stuff

* more

* Add middleware/cache

Add a caching middleware that caches nxdomain, nodata and successful
responses. It differentiates between DNSSEC on normal DNS replies.

Each reply is compressed and scrubbed so it will fit the specific client
asking for it. The TTL is decremented with the time spend in the cache.
There is syntax that allows you to cap the TTL for all records, no
matter what. This allows for a shortlived cache, just to absorb query
peaks.

+Tests

* cache test infrastructure

* Testing

1 files changed, 112 insertions, 0 deletions

diff --git a/middleware/cache/cache_test.go b/middleware/cache/cache_test.go
new file mode 100644
index 000000000..310a1164e
--- /dev/null
+++ b/middleware/cache/cache_test.go
@@ -0,0 +1,112 @@
+package cache
+
+import (
+	"testing"
+	"time"
+
+	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/test"
+
+	"github.com/miekg/dns"
+)
+
+type cacheTestCase struct {
+	test.Case
+	in                 test.Case
+	AuthenticatedData  bool
+	Authoritative      bool
+	RecursionAvailable bool
+	Truncated          bool
+}
+
+var cacheTestCases = []cacheTestCase{
+	{
+		RecursionAvailable: true, AuthenticatedData: true, Authoritative: true,
+		Case: test.Case{
+			Qname: "miek.nl.", Qtype: dns.TypeMX,
+			Answer: []dns.RR{
+				test.MX("miek.nl.	1800	IN	MX	1 aspmx.l.google.com."),
+				test.MX("miek.nl.	1800	IN	MX	10 aspmx2.googlemail.com."),
+				test.MX("miek.nl.	1800	IN	MX	10 aspmx3.googlemail.com."),
+				test.MX("miek.nl.	1800	IN	MX	5 alt1.aspmx.l.google.com."),
+				test.MX("miek.nl.	1800	IN	MX	5 alt2.aspmx.l.google.com."),
+			},
+		},
+		in: test.Case{
+			Qname: "miek.nl.", Qtype: dns.TypeMX,
+			Answer: []dns.RR{
+				test.MX("miek.nl.	1800	IN	MX	1 aspmx.l.google.com."),
+				test.MX("miek.nl.	1800	IN	MX	10 aspmx2.googlemail.com."),
+				test.MX("miek.nl.	1800	IN	MX	10 aspmx3.googlemail.com."),
+				test.MX("miek.nl.	1800	IN	MX	5 alt1.aspmx.l.google.com."),
+				test.MX("miek.nl.	1800	IN	MX	5 alt2.aspmx.l.google.com."),
+			},
+		},
+	},
+	{
+		Truncated: true,
+		Case: test.Case{
+			Qname: "miek.nl.", Qtype: dns.TypeMX,
+			Answer: []dns.RR{test.MX("miek.nl.	1800	IN	MX	1 aspmx.l.google.com.")},
+		},
+		in: test.Case{},
+	},
+}
+
+func cacheMsg(m *dns.Msg, tc cacheTestCase) *dns.Msg {
+	m.RecursionAvailable = tc.RecursionAvailable
+	m.AuthenticatedData = tc.AuthenticatedData
+	m.Authoritative = tc.Authoritative
+	m.Truncated = tc.Truncated
+	m.Answer = tc.in.Answer
+	m.Ns = tc.in.Ns
+	//	m.Extra = tc.in.Extra , not the OPT record!
+	return m
+}
+
+func newTestCache() (Cache, *CachingResponseWriter) {
+	c := NewCache(0, []string{"."}, nil)
+	crr := NewCachingResponseWriter(nil, c.cache, time.Duration(0))
+	return c, crr
+}
+
+func TestCache(t *testing.T) {
+	c, crr := newTestCache()
+
+	for _, tc := range cacheTestCases {
+		m := tc.in.Msg()
+		m = cacheMsg(m, tc)
+		do := tc.in.Do
+
+		mt, _ := classify(m)
+		key := cacheKey(m, mt, do)
+		crr.Set(m, key, mt)
+
+		name := middleware.Name(m.Question[0].Name).Normalize()
+		qtype := m.Question[0].Qtype
+		i, ok := c.Get(name, qtype, do)
+		if !ok && !m.Truncated {
+			t.Errorf("Truncated message should not have been cached")
+		}
+
+		if ok {
+			resp := i.toMsg(m)
+
+			if !test.Header(t, tc.Case, resp) {
+				t.Logf("%v\n", resp)
+				continue
+			}
+
+			if !test.Section(t, tc.Case, test.Answer, resp.Answer) {
+				t.Logf("%v\n", resp)
+			}
+			if !test.Section(t, tc.Case, test.Ns, resp.Ns) {
+				t.Logf("%v\n", resp)
+
+			}
+			if !test.Section(t, tc.Case, test.Extra, resp.Extra) {
+				t.Logf("%v\n", resp)
+			}
+		}
+	}
+}