Support SkyDNS' stubzones

This implements stubzones in the same way as SkyDNS. This
also works with multiple configured domains and has tests.
Also add more configuration parameters for TLS and path prefix and
enabling stubzones.  Run StubUpdates as a startup command to keep up to
date with the list in etcd.

core/setup/etcd.go

@@ -21,10 +21,16 @@ const defaultEndpoint = "http://127.0.0.1:2379"
 
 // Etcd sets up the etcd middleware.
 func Etcd(c *Controller) (middleware.Middleware, error) {
-	etcd, err := etcdParse(c)
+	etcd, stubzones, err := etcdParse(c)
 	if err != nil {
 		return nil, err
 	}
+	if stubzones {
+		c.Startup = append(c.Startup, func() error {
+			etcd.UpdateStubZones()
+			return nil
+		})
+	}
 
 	return func(next middleware.Handler) middleware.Handler {
 		etcd.Next = next
@@ -32,31 +38,113 @@ func Etcd(c *Controller) (middleware.Middleware, error) {
 	}, nil
 }
 
-func etcdParse(c *Controller) (etcd.Etcd, error) {
+func etcdParse(c *Controller) (etcd.Etcd, bool, error) {
+	stub := make(map[string]proxy.Proxy)
 	etc := etcd.Etcd{
-		// make stuff configurable
 		Proxy:      proxy.New([]string{"8.8.8.8:53"}),
 		PathPrefix: "skydns",
 		Ctx:        context.Background(),
 		Inflight:   &singleflight.Group{},
+		Stubmap:    &stub,
 	}
+	var (
+		client        etcdc.KeysAPI
+		tlsCertFile   = ""
+		tlsKeyFile    = ""
+		tlsCAcertFile = ""
+		endpoints     = []string{defaultEndpoint}
+		stubzones     = false
+	)
 	for c.Next() {
 		if c.Val() == "etcd" {
-			// etcd [origin...]
-			client, err := newEtcdClient([]string{defaultEndpoint}, "", "", "")
-			if err != nil {
-				return etcd.Etcd{}, err
-			}
 			etc.Client = client
 			etc.Zones = c.RemainingArgs()
 			if len(etc.Zones) == 0 {
 				etc.Zones = c.ServerBlockHosts
 			}
 			middleware.Zones(etc.Zones).FullyQualify()
-			return etc, nil
+			if c.NextBlock() {
+				// TODO(miek): 2 switches?
+				switch c.Val() {
+				case "stubzones":
+					stubzones = true
+				case "path":
+					if !c.NextArg() {
+						return etcd.Etcd{}, false, c.ArgErr()
+					}
+					etc.PathPrefix = c.Val()
+				case "endpoint":
+					args := c.RemainingArgs()
+					if len(args) == 0 {
+						return etcd.Etcd{}, false, c.ArgErr()
+					}
+					endpoints = args
+				case "upstream":
+					args := c.RemainingArgs()
+					if len(args) == 0 {
+						return etcd.Etcd{}, false, c.ArgErr()
+					}
+					for i := 0; i < len(args); i++ {
+						h, p, e := net.SplitHostPort(args[i])
+						if e != nil && p == "" {
+							args[i] = h + ":53"
+						}
+					}
+					endpoints = args
+					etc.Proxy = proxy.New(args)
+				case "tls": // cert key cacertfile
+					args := c.RemainingArgs()
+					if len(args) != 3 {
+						return etcd.Etcd{}, false, c.ArgErr()
+					}
+					tlsCertFile, tlsKeyFile, tlsCAcertFile = args[0], args[1], args[2]
+				}
+				for c.Next() {
+					switch c.Val() {
+					case "stubzones":
+						stubzones = true
+					case "path":
+						if !c.NextArg() {
+							return etcd.Etcd{}, false, c.ArgErr()
+						}
+						etc.PathPrefix = c.Val()
+					case "endpoint":
+						args := c.RemainingArgs()
+						if len(args) == 0 {
+							return etcd.Etcd{}, false, c.ArgErr()
+						}
+						endpoints = args
+					case "upstream":
+						args := c.RemainingArgs()
+						if len(args) == 0 {
+							return etcd.Etcd{}, false, c.ArgErr()
+						}
+						for i := 0; i < len(args); i++ {
+							h, p, e := net.SplitHostPort(args[i])
+							if e != nil && p == "" {
+								args[i] = h + ":53"
+							}
+						}
+						endpoints = args
+						etc.Proxy = proxy.New(args)
+					case "tls": // cert key cacertfile
+						args := c.RemainingArgs()
+						if len(args) != 3 {
+							return etcd.Etcd{}, false, c.ArgErr()
+						}
+						tlsCertFile, tlsKeyFile, tlsCAcertFile = args[0], args[1], args[2]
+					}
+				}
+			}
+			client, err := newEtcdClient(endpoints, tlsCertFile, tlsKeyFile, tlsCAcertFile)
+			if err != nil {
+				return etcd.Etcd{}, false, err
+			}
+			etc.Client = client
+			return etc, stubzones, nil
 		}
 	}
-	return etcd.Etcd{}, nil
+	return etcd.Etcd{}, false, nil
 }
 
 func newEtcdClient(endpoints []string, tlsCert, tlsKey, tlsCACert string) (etcdc.KeysAPI, error) {