Middleware chaining fixes

For prometheus use the plain value, not a pointer and change all usages.
Allow AXFR to be requested over udp as well and some other more log
printed when commencing an AXFR.

core/directives.go

@@ -51,8 +51,8 @@ var directiveOrder = []directive{
 	{"shutdown", setup.Shutdown},
 
 	// Directives that inject handlers (middleware)
-	{"log", setup.Log},
 	{"prometheus", setup.Prometheus},
+	{"log", setup.Log},
 	{"rewrite", setup.Rewrite},
 	{"loadbalance", setup.Loadbalance},
 	{"file", setup.File},

core/setup/prometheus.go

@@ -32,17 +32,17 @@ func Prometheus(c *Controller) (middleware.Middleware, error) {
 	}, nil
 }
 
-func parsePrometheus(c *Controller) (*prom.Metrics, error) {
+func parsePrometheus(c *Controller) (prom.Metrics, error) {
 	var (
-		metrics *prom.Metrics
+		metrics prom.Metrics
 		err     error
 	)
 
 	for c.Next() {
-		if metrics != nil {
+		if metrics.Addr != "" {
-			return nil, c.Err("prometheus: can only have one metrics module per server")
+			return prom.Metrics{}, c.Err("prometheus: can only have one metrics module per server")
 		}
-		metrics = &prom.Metrics{ZoneNames: c.ServerBlockHosts}
+		metrics = prom.Metrics{ZoneNames: c.ServerBlockHosts}
 		args := c.RemainingArgs()
 
 		switch len(args) {
@@ -50,18 +50,18 @@ func parsePrometheus(c *Controller) (*prom.Metrics, error) {
 		case 1:
 			metrics.Addr = args[0]
 		default:
-			return nil, c.ArgErr()
+			return prom.Metrics{}, c.ArgErr()
 		}
 		for c.NextBlock() {
 			switch c.Val() {
 			case "address":
 				args = c.RemainingArgs()
 				if len(args) != 1 {
-					return nil, c.ArgErr()
+					return prom.Metrics{}, c.ArgErr()
 				}
 				metrics.Addr = args[0]
 			default:
-				return nil, c.Errf("prometheus: unknown item: %s", c.Val())
+				return prom.Metrics{}, c.Errf("prometheus: unknown item: %s", c.Val())
 			}
 
 		}

middleware/etcd/handler.go

@@ -1,7 +1,6 @@
 package etcd
 
 import (
-	"fmt"
 	"strings"
 
 	"github.com/miekg/coredns/middleware"
@@ -13,7 +12,7 @@ import (
 func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := middleware.State{W: w, Req: r}
 	if state.QClass() != dns.ClassINET {
-		return dns.RcodeServerFailure, fmt.Errorf("etcd: can only deal with ClassINET")
+		return e.Next.ServeDNS(ctx, w, r)
 	}
 
 	// We need to check stubzones first, because we may get a request for a zone we

middleware/file/file.go

@@ -1,7 +1,6 @@
 package file
 
 import (
-	"fmt"
 	"io"
 	"log"
 
@@ -26,7 +25,7 @@ type (
 func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := middleware.State{W: w, Req: r}
 	if state.QClass() != dns.ClassINET {
-		return dns.RcodeServerFailure, fmt.Errorf("file: can only deal with ClassINET")
+		return f.Next.ServeDNS(ctx, w, r)
 	}
 	qname := state.Name()
 	zone := middleware.Zones(f.Zones.Names).Matches(qname)
@@ -63,7 +62,7 @@ func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 		return dns.RcodeServerFailure, nil
 	}
 
-	if state.Proto() != "udp" && state.QType() == dns.TypeAXFR {
+	if state.QType() == dns.TypeAXFR || state.QType() == dns.TypeIXFR {
 		xfr := Xfr{z}
 		return xfr.ServeDNS(ctx, w, r)
 	}

middleware/file/xfr.go

@@ -2,6 +2,7 @@ package file
 
 import (
 	"fmt"
+	"log"
 
 	"github.com/miekg/coredns/middleware"
 
@@ -24,9 +25,6 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
 	if state.QType() != dns.TypeAXFR {
 		return 0, fmt.Errorf("xfr called with non transfer type: %d", state.QType())
 	}
-	if state.Proto() == "udp" {
-		return 0, fmt.Errorf("xfr called with udp")
-	}
 
 	records := x.All()
 	if len(records) == 0 {
@@ -40,6 +38,7 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
 
 	j, l := 0, 0
 	records = append(records, records[0]) // add closing SOA to the end
+	log.Printf("[INFO] Outgoing transfer of %d records of zone %s to %s started", len(records), x.name, state.IP())
 	for i, r := range records {
 		l += dns.Len(r)
 		if l > transferLength {
@@ -57,4 +56,4 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
 	return dns.RcodeSuccess, nil
 }
 
-const transferLength = 100 // Start a new envelop after message reaches this size. Intentionally small to test multi envelope parsing
+const transferLength = 1000 // Start a new envelop after message reaches this size in bytes. Intentionally small to test multi envelope parsing.

middleware/prometheus/handler.go

@@ -10,7 +10,7 @@ import (
 	"github.com/miekg/dns"
 )
 
-func (m *Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+func (m Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := middleware.State{W: w, Req: r}
 
 	qname := state.Name()