5 files changed, 59 insertions, 15 deletions
diff --git a/middleware/httpproxy/README.md b/middleware/httpproxy/README.md
index 026fbdc71..f0bf58903 100644
--- a/middleware/httpproxy/README.md
+++ b/middleware/httpproxy/README.md
@@ -48,3 +48,24 @@ proxy . dns.google.com {
     upstream /etc/resolv.conf
 }
 ~~~
+
+## Debug queries
+
+Debug queries are enabled by default and currently there is no way to turn them off. When CoreDNS
+receives a debug queries (i.e. the name is prefixed with `o-o.debug.` a TXT record with Comment from
+`dns.google.com` is added. Note this is not always set, but sometimes you'll see:
+
+`dig @localhost -p 1053 mx o-o.debug.example.org`:
+
+~~~ txt
+;; OPT PSEUDOSECTION:
+; EDNS: version: 0, flags:; udp: 4096
+;; QUESTION SECTION:
+;o-o.debug.example.org.		IN	MX
+
+;; AUTHORITY SECTION:
+example.org.		1799	IN	SOA	sns.dns.icann.org. noc.dns.icann.org. 2016110711 7200 3600 1209600 3600
+
+;; ADDITIONAL SECTION:
+.			0	CH	TXT	"Response from 199.43.133.53"
+~~~
diff --git a/middleware/httpproxy/google.go b/middleware/httpproxy/google.go
index 78b5ea864..dafd0d6a6 100644
--- a/middleware/httpproxy/google.go
+++ b/middleware/httpproxy/google.go
@@ -12,7 +12,9 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/miekg/coredns/middleware/pkg/debug"
 	"github.com/miekg/coredns/middleware/proxy"
+	"github.com/miekg/coredns/request"
 
 	"github.com/miekg/dns"
 )
@@ -30,11 +32,17 @@ type google struct {
 
 func newGoogle() *google { return &google{client: newClient(ghost), quit: make(chan bool)} }
 
-func (g *google) Exchange(req *dns.Msg) (*dns.Msg, error) {
+func (g *google) Exchange(state request.Request) (*dns.Msg, error) {
 	v := url.Values{}
 
-	v.Set("name", req.Question[0].Name)
-	v.Set("type", fmt.Sprintf("%d", req.Question[0].Qtype))
+	v.Set("name", state.Name())
+	v.Set("type", fmt.Sprintf("%d", state.QType()))
+
+	optDebug := false
+	if bug := debug.IsDebug(state.Name()); bug != "" {
+		optDebug = true
+		v.Set("name", bug)
+	}
 
 	start := time.Now()
 
@@ -60,12 +68,20 @@ func (g *google) Exchange(req *dns.Msg) (*dns.Msg, error) {
 				return nil, err
 			}
 
-			m, err := toMsg(gm)
+			m, debug, err := toMsg(gm)
 			if err != nil {
 				return nil, err
 			}
 
-			m.Id = req.Id
+			if optDebug {
+				// reset question
+				m.Question[0].Name = state.QName()
+				// prepend debug RR to the additional section
+				m.Extra = append([]dns.RR{debug}, m.Extra...)
+
+			}
+
+			m.Id = state.Req.Id
 			return m, nil
 		}
 
@@ -223,8 +239,11 @@ func (g *google) do(addr, json string) ([]byte, error) {
 	return buf, nil
 }
 
-func toMsg(g *googleMsg) (*dns.Msg, error) {
+// toMsg converts a googleMsg into the dns message. The returned RR is the comment disquised as a TXT
+// record.
+func toMsg(g *googleMsg) (*dns.Msg, dns.RR, error) {
 	m := new(dns.Msg)
+	m.Response = true
 	m.Rcode = g.Status
 	m.Truncated = g.TC
 	m.RecursionDesired = g.RD
@@ -243,23 +262,24 @@ func toMsg(g *googleMsg) (*dns.Msg, error) {
 	for i := 0; i < len(m.Answer); i++ {
 		m.Answer[i], err = toRR(g.Answer[i])
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 	for i := 0; i < len(m.Ns); i++ {
 		m.Ns[i], err = toRR(g.Authority[i])
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 	for i := 0; i < len(m.Extra); i++ {
 		m.Extra[i], err = toRR(g.Additional[i])
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 
-	return m, nil
+	txt, _ := dns.NewRR(". 0 CH TXT " + g.Comment)
+	return m, txt, nil
 }
 
 func toRR(g googleRR) (dns.RR, error) {
diff --git a/middleware/httpproxy/proxy.go b/middleware/httpproxy/proxy.go
index 6b1243dff..3ef638a8f 100644
--- a/middleware/httpproxy/proxy.go
+++ b/middleware/httpproxy/proxy.go
@@ -27,9 +27,9 @@ func (p *Proxy) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 	start := time.Now()
 	state := request.Request{W: w, Req: r}
 
-	reply, backendErr := p.e.Exchange(r)
+	reply, backendErr := p.e.Exchange(state)
 
-	if backendErr == nil {
+	if backendErr == nil && reply != nil {
 		state.SizeAndDo(reply)
 
 		w.WriteMsg(reply)
diff --git a/middleware/httpproxy/setup_test.go b/middleware/httpproxy/setup_test.go
index 71d631220..82db40aff 100644
--- a/middleware/httpproxy/setup_test.go
+++ b/middleware/httpproxy/setup_test.go
@@ -2,6 +2,7 @@ package httpproxy
 
 import (
 	"io/ioutil"
+	"log"
 	"os"
 	"strings"
 	"testing"
@@ -9,7 +10,9 @@ import (
 	"github.com/mholt/caddy"
 )
 
-func TestSetupChaos(t *testing.T) {
+func TestSetupHttpproxy(t *testing.T) {
+	log.SetOutput(ioutil.Discard)
+
 	tests := []struct {
 		input              string
 		shouldErr          bool
@@ -55,7 +58,6 @@ func TestSetupChaos(t *testing.T) {
 		}
 
 		if err != nil {
-			t.Logf("%q", err)
 			if !test.shouldErr {
 				t.Errorf("Test %d: Expected no error but found one for input %s. Error was: %v", i, test.input, err)
 			}
diff --git a/middleware/httpproxy/tls.go b/middleware/httpproxy/tls.go
index 9651ac1c6..2c05a0331 100644
--- a/middleware/httpproxy/tls.go
+++ b/middleware/httpproxy/tls.go
@@ -5,13 +5,14 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/miekg/coredns/request"
 	"github.com/miekg/dns"
 )
 
 // Exchanger is an interface that specifies a type implementing a DNS resolver that
 // uses a HTTPS server.
 type Exchanger interface {
-	Exchange(*dns.Msg) (*dns.Msg, error)
+	Exchange(request.Request) (*dns.Msg, error)
 
 	SetUpstream(*simpleUpstream) error
 	OnStartup() error