return nxdomain for all domains if resolution is disabled

cmd/pancheri/main.go

@@ -44,9 +44,23 @@ func main() {
 		}).Info("enabling upstream resolver")
 
 		r = pancheri.NewResolver(c.Resolver.Upstream)
-		err = r.Resolve("example.com", dns.TypeA)
-		if err != nil {
-			logrus.Errorf("failed to resolve: %s", err)
-		}
+	}
+
+	handler := pancheri.Handler{
+		C: c,
+		R: r,
+	}
+	server := &dns.Server{
+		Addr:      c.Server.Host + ":" + c.Server.Port,
+		Net:       "udp",
+		Handler:   &handler,
+		UDPSize:   65535,
+		ReusePort: true,
+	}
+	err = server.ListenAndServe()
+
+	if err != nil {
+		logrus.Errorf("failed to start server: %s", err)
+		os.Exit(1)
 	}
 }

handler.go

@@ -0,0 +1,57 @@
+package pancheri
+
+import (
+	"github.com/miekg/dns"
+	"github.com/sirupsen/logrus"
+)
+
+type Handler struct {
+	C *Config
+	R *Resolver
+}
+
+func (h *Handler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
+
+	// figure out how we should resolve this
+
+	// is this in our list of authoritative domains?
+	// TODO
+
+	// okay, do we have upstream resolution enabled?
+	if h.C.Resolver.Enable {
+		// alright, resolve it with the resolver
+		msg := new(dns.Msg)
+		msg.SetReply(r)
+		msg.Authoritative = true
+
+		for _, question := range r.Question {
+			answers, err := h.R.Resolve(question.Name, question.Qtype)
+			if err != nil {
+				logrus.Errorf("error resolving: %s", err)
+				return
+			}
+			msg.Answer = append(msg.Answer, answers...)
+		}
+
+		err := w.WriteMsg(msg)
+		if err != nil {
+			logrus.Errorf("error responding: %s", err)
+			return
+		}
+	} else {
+		// alright, send an nxdomain
+		msg := new(dns.Msg)
+		msg.SetReply(r)
+		msg.Authoritative = true
+		if r.RecursionDesired {
+			msg.RecursionAvailable = true
+		}
+		msg.Rcode = dns.RcodeNameError
+
+		err := w.WriteMsg(msg)
+		if err != nil {
+			logrus.Errorf("error responding: %s", err)
+			return
+		}
+	}
+}

resolver.go

@@ -17,7 +17,7 @@ func NewResolver(upstream string) *Resolver {
 	}
 }
 
-func (r *Resolver) Resolve(domain string, qtype uint16) error {
+func (r *Resolver) Resolve(domain string, qtype uint16) ([]dns.RR, error) {
 	logrus.WithFields(logrus.Fields{
 		"domain": domain,
 		"qtype":  qtype,
@@ -30,12 +30,8 @@ func (r *Resolver) Resolve(domain string, qtype uint16) error {
 	in, _, err := r.client.Exchange(m, r.upstream)
 
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	for _, ans := range in.Answer {
-		logrus.Debug(ans)
-	}
-
-	return nil
+	return in.Answer, nil
 }