Add middleware/dnssec (#133)

This adds an online dnssec middleware. The middleware will sign
responses on the fly. Negative responses are signed with NSEC black
lies.

middleware/etcd/etcd.go

@@ -8,8 +8,8 @@ import (
 
 	"github.com/miekg/coredns/middleware"
 	"github.com/miekg/coredns/middleware/etcd/msg"
-	"github.com/miekg/coredns/middleware/etcd/singleflight"
 	"github.com/miekg/coredns/middleware/proxy"
+	"github.com/miekg/coredns/middleware/singleflight"
 
 	etcdc "github.com/coreos/etcd/client"
 	"golang.org/x/net/context"

middleware/etcd/lookup.go

@@ -317,11 +317,14 @@ func (e Etcd) NS(zone string, state middleware.State) (records, extra []dns.RR,
 	// NS record for this zone live in a special place, ns.dns.<zone>. Fake our lookup.
 	// only a tad bit fishy...
 	old := state.QName()
+
+	state.Clear()
 	state.Req.Question[0].Name = "ns.dns." + zone
 	services, err := e.records(state, false)
 	if err != nil {
 		return nil, nil, err
 	}
+	// ... and reset
 	state.Req.Question[0].Name = old
 
 	for _, serv := range services {

middleware/etcd/setup_test.go

@@ -10,8 +10,8 @@ import (
 
 	"github.com/miekg/coredns/middleware"
 	"github.com/miekg/coredns/middleware/etcd/msg"
-	"github.com/miekg/coredns/middleware/etcd/singleflight"
 	"github.com/miekg/coredns/middleware/proxy"
+	"github.com/miekg/coredns/middleware/singleflight"
 	"github.com/miekg/coredns/middleware/test"
 	"github.com/miekg/dns"
 

middleware/etcd/singleflight/singleflight.go

@@ -1,64 +0,0 @@
-/*
-Copyright 2012 Google Inc.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-     http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-// Package singleflight provides a duplicate function call suppression
-// mechanism.
-package singleflight
-
-import "sync"
-
-// call is an in-flight or completed Do call
-type call struct {
-	wg  sync.WaitGroup
-	val interface{}
-	err error
-}
-
-// Group represents a class of work and forms a namespace in which
-// units of work can be executed with duplicate suppression.
-type Group struct {
-	mu sync.Mutex       // protects m
-	m  map[string]*call // lazily initialized
-}
-
-// Do executes and returns the results of the given function, making
-// sure that only one execution is in-flight for a given key at a
-// time. If a duplicate comes in, the duplicate caller waits for the
-// original to complete and receives the same results.
-func (g *Group) Do(key string, fn func() (interface{}, error)) (interface{}, error) {
-	g.mu.Lock()
-	if g.m == nil {
-		g.m = make(map[string]*call)
-	}
-	if c, ok := g.m[key]; ok {
-		g.mu.Unlock()
-		c.wg.Wait()
-		return c.val, c.err
-	}
-	c := new(call)
-	c.wg.Add(1)
-	g.m[key] = c
-	g.mu.Unlock()
-
-	c.val, c.err = fn()
-	c.wg.Done()
-
-	g.mu.Lock()
-	delete(g.m, key)
-	g.mu.Unlock()
-
-	return c.val, c.err
-}