Fix stubzone retention (#198)

Make the receiver a pointer so that the uptdateStubZones map update will
retain the stubzones found, unlike the current case where the update
will be applied and then promptly forgotten, because it is working on a
copy.

Add test/etcd_test.go to test a large part of the code. This didn't
catch the chaos middleware hack though. The chaos middleware zones are
now *not* automatically added. You have to take care of that by yourself
(docs updates).

When using debug queries and falling through to the next middleware in
etcd, restore the original (with o-o.debug) query before passing it on.

1 files changed, 25 insertions, 21 deletions

diff --git a/middleware/etcd/handler.go b/middleware/etcd/handler.go
index cef319dbf..132dba370 100644
--- a/middleware/etcd/handler.go
+++ b/middleware/etcd/handler.go
@@ -10,7 +10,8 @@ import (
 	"golang.org/x/net/context"
 )
 
-func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+func (e *Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	opt := Options{}
 	state := middleware.State{W: w, Req: r}
 	if state.QClass() != dns.ClassINET {
 		return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
@@ -18,7 +19,7 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 	name := state.Name()
 	if e.Debug {
 		if debug := isDebug(name); debug != "" {
-			e.debug = r.Question[0].Name
+			opt.Debug = r.Question[0].Name
 			state.Clear()
 			state.Req.Question[0].Name = debug
 		}
@@ -41,6 +42,9 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 		if e.Next == nil {
 			return dns.RcodeServerFailure, nil
 		}
+		if opt.Debug != "" {
+			r.Question[0].Name = opt.Debug
+		}
 		return e.Next.ServeDNS(ctx, w, r)
 	}
 
@@ -51,47 +55,47 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 	)
 	switch state.Type() {
 	case "A":
-		records, debug, err = e.A(zone, state, nil)
+		records, debug, err = e.A(zone, state, nil, opt)
 	case "AAAA":
-		records, debug, err = e.AAAA(zone, state, nil)
+		records, debug, err = e.AAAA(zone, state, nil, opt)
 	case "TXT":
-		records, debug, err = e.TXT(zone, state)
+		records, debug, err = e.TXT(zone, state, opt)
 	case "CNAME":
-		records, debug, err = e.CNAME(zone, state)
+		records, debug, err = e.CNAME(zone, state, opt)
 	case "PTR":
-		records, debug, err = e.PTR(zone, state)
+		records, debug, err = e.PTR(zone, state, opt)
 	case "MX":
-		records, extra, debug, err = e.MX(zone, state)
+		records, extra, debug, err = e.MX(zone, state, opt)
 	case "SRV":
-		records, extra, debug, err = e.SRV(zone, state)
+		records, extra, debug, err = e.SRV(zone, state, opt)
 	case "SOA":
-		records, debug, err = e.SOA(zone, state)
+		records, debug, err = e.SOA(zone, state, opt)
 	case "NS":
 		if state.Name() == zone {
-			records, extra, debug, err = e.NS(zone, state)
+			records, extra, debug, err = e.NS(zone, state, opt)
 			break
 		}
 		fallthrough
 	default:
 		// Do a fake A lookup, so we can distinguish between NODATA and NXDOMAIN
-		_, debug, err = e.A(zone, state, nil)
+		_, debug, err = e.A(zone, state, nil, opt)
 	}
 
-	if e.debug != "" {
+	if opt.Debug != "" {
 		// Substitute this name with the original when we return the request.
 		state.Clear()
-		state.Req.Question[0].Name = e.debug
+		state.Req.Question[0].Name = opt.Debug
 	}
 
 	if isEtcdNameError(err) {
-		return e.Err(zone, dns.RcodeNameError, state, debug, err)
+		return e.Err(zone, dns.RcodeNameError, state, debug, err, opt)
 	}
 	if err != nil {
-		return e.Err(zone, dns.RcodeServerFailure, state, debug, err)
+		return e.Err(zone, dns.RcodeServerFailure, state, debug, err, opt)
 	}
 
 	if len(records) == 0 {
-		return e.Err(zone, dns.RcodeSuccess, state, debug, err)
+		return e.Err(zone, dns.RcodeSuccess, state, debug, err, opt)
 	}
 
 	m := new(dns.Msg)
@@ -99,7 +103,7 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
 	m.Answer = append(m.Answer, records...)
 	m.Extra = append(m.Extra, extra...)
-	if e.debug != "" {
+	if opt.Debug != "" {
 		m.Extra = append(m.Extra, servicesToTxt(debug)...)
 	}
 
@@ -111,12 +115,12 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 }
 
 // Err write an error response to the client.
-func (e Etcd) Err(zone string, rcode int, state middleware.State, debug []msg.Service, err error) (int, error) {
+func (e *Etcd) Err(zone string, rcode int, state middleware.State, debug []msg.Service, err error, opt Options) (int, error) {
 	m := new(dns.Msg)
 	m.SetRcode(state.Req, rcode)
 	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
-	m.Ns, _, _ = e.SOA(zone, state)
-	if e.debug != "" {
+	m.Ns, _, _ = e.SOA(zone, state, opt)
+	if opt.Debug != "" {
 		m.Extra = servicesToTxt(debug)
 		txt := errorToTxt(err)
 		if txt != nil {