Move handleMDNS into server file

main.go

@@ -31,23 +31,6 @@ var (
 	mdnsServer *weavedns.MDNSServer
 )
 
-func handleMDNS(w dns.ResponseWriter, r *dns.Msg) {
-	// Ignore answers to other questions
-	if len(r.Answer) == 0 && len(r.Question) > 0 {
-		q := r.Question[0]
-		ip, err := zone.MatchLocal(q.Name)
-		if err == nil {
-			m := makeDNSReply(r, q.Name, ip)
-			mdnsServer.SendResponse(m)
-		} else if mdnsClient.IsInflightQuery(r) {
-			log.Println("Inflight Query", w.RemoteAddr(), w.LocalAddr())
-			// ignore this - it's our own query received via multicast
-		} else {
-			log.Printf("Failed MDNS lookup for %s", q.Name)
-		}
-	}
-}
-
 func handleLocal(w dns.ResponseWriter, r *dns.Msg) {
 	q := r.Question[0]
 	ip, err := zone.MatchLocal(q.Name)
@@ -123,13 +106,7 @@ func main() {
 	LocalServeMux.HandleFunc(LOCAL_DOMAIN, handleLocal)
 	go weavedns.ListenHttp(zone)
 
-	MDNSServeMux := dns.NewServeMux()
-	MDNSServeMux.HandleFunc(LOCAL_DOMAIN, handleMDNS)
-
-	conn, err := weavedns.LinkLocalMulticastListener(iface)
-	if err != nil {
-		log.Fatal(err)
-	}
+	var err error
 	mdnsClient, err = weavedns.NewMDNSClient()
 	if err != nil {
 		log.Fatal(err)
@@ -140,12 +117,14 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	mdnsServer, err = weavedns.NewMDNSServer()
+	mdnsServer, err = weavedns.NewMDNSServer(zone)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = mdnsServer.Start(iface)
 	if err != nil {
 		log.Fatal(err)
 	}
-
-	go dns.ActivateAndServe(nil, conn, MDNSServeMux)
 
 	address := fmt.Sprintf(":%d", dnsPort)
 	err = dns.ListenAndServe(address, "udp", LocalServeMux)

server/mdns_server.go

@@ -2,24 +2,83 @@ package weavedns
 
 import (
 	"github.com/miekg/dns"
+	"log"
 	"net"
 )
 
 type MDNSServer struct {
-	sendconn *net.UDPConn
+	localAddrs []net.Addr
+	sendconn   *net.UDPConn
+	zone       *ZoneDb
 }
 
-func NewMDNSServer() (*MDNSServer, error) {
+func NewMDNSServer(zone *ZoneDb) (*MDNSServer, error) {
 	//log.Println("minimalServer sending:", buf)
 	// This is a bit of a kludge - per the RFC we should send responses from 5353, but that doesn't seem to work
 	sendconn, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
 	if err != nil {
 		return nil, err
 	}
-	retval := &MDNSServer{sendconn: sendconn}
+	retval := &MDNSServer{sendconn: sendconn, zone: zone}
+
 	return retval, nil
 }
 
+func makeDNSReply(r *dns.Msg, name string, addr net.IP) *dns.Msg {
+	m := new(dns.Msg)
+	m.SetReply(r)
+	hdr := dns.RR_Header{Name: name, Rrtype: dns.TypeA,
+		Class: dns.ClassINET, Ttl: 3600}
+	a := &dns.A{hdr, addr}
+	m.Answer = append(m.Answer, a)
+	return m
+}
+
+// Return true if testaddr is a UDP address with IP matching my local i/f
+func (s *MDNSServer) addrIsLocal(testaddr net.Addr) bool {
+	if udpaddr, ok := testaddr.(*net.UDPAddr); ok {
+		for _, localaddr := range s.localAddrs {
+			if ipnetlocal, ok := localaddr.(*net.IPNet); ok {
+				if ipnetlocal.IP.Equal(udpaddr.IP) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func (s *MDNSServer) Start(ifi *net.Interface) error {
+	handleMDNS := func(w dns.ResponseWriter, r *dns.Msg) {
+		// Ignore answers to other questions
+		if len(r.Answer) == 0 && len(r.Question) > 0 {
+			q := r.Question[0]
+			ip, err := s.zone.MatchLocal(q.Name)
+			if err == nil {
+				m := makeDNSReply(r, q.Name, ip)
+				s.SendResponse(m)
+			} else if s.addrIsLocal(w.RemoteAddr()) {
+				// ignore this - it's our own query received via multicast
+			} else {
+				log.Printf("Failed MDNS lookup for %s", q.Name)
+			}
+		}
+	}
+
+	conn, err := LinkLocalMulticastListener(ifi)
+	if err != nil {
+		return err
+	}
+	s.localAddrs, err = ifi.Addrs()
+	if err != nil {
+		return err
+	}
+
+	go dns.ActivateAndServe(nil, conn, dns.HandlerFunc(handleMDNS))
+
+	return err
+}
+
 func (s *MDNSServer) SendResponse(m *dns.Msg) error {
 	buf, err := m.Pack()
 	if err != nil {