also respond with records for the host itself

setup.go

@@ -2,6 +2,7 @@ package wgsd
 
 import (
 	"fmt"
+	"net"
 
 	"github.com/coredns/caddy"
 	"github.com/coredns/coredns/core/dnsserver"
@@ -29,6 +30,14 @@ func setup(c *caddy.Controller) error {
 	}
 	device := c.Val()
 
+	// parse optional local ip
+	var wgIP net.IP
+	if c.NextArg() {
+		wgIP = net.ParseIP(c.Val())
+	} else {
+		wgIP = getOutboundIP()
+	}
+
 	// return an error if there are more tokens on this line
 	if c.NextArg() {
 		return plugin.Error("wgsd", c.ArgErr())
@@ -48,8 +57,20 @@ func setup(c *caddy.Controller) error {
 			client: client,
 			zone:   zone,
 			device: device,
+			wgIP:   wgIP,
 		}
 	})
 
 	return nil
 }
+
+// Get preferred outbound ip of this machine
+func getOutboundIP() net.IP {
+	conn, err := net.Dial("udp", "1.1.1.1:80")
+	if err != nil {
+		return nil
+	}
+	defer conn.Close()
+
+	return conn.LocalAddr().(*net.UDPAddr).IP
+}

wgsd.go

@@ -28,12 +28,19 @@ type WGSD struct {
 	zone string
 	// the Wireguard device name, e.g. wg0
 	device string
+	// the IP the local wireguard is running on
+	wgIP net.IP
 }
 
 type wgctrlClient interface {
 	Device(string) (*wgtypes.Device, error)
 }
 
+type host struct {
+	PublicKey wgtypes.Key
+	Endpoint  *net.UDPAddr
+}
+
 const (
 	keyLen             = 56 // the number of characters in a base32-encoded Wireguard public key
 	spPrefix           = "_wireguard._udp."
@@ -63,19 +70,26 @@ func (p *WGSD) ServeDNS(ctx context.Context, w dns.ResponseWriter,
 	if err != nil {
 		return dns.RcodeServerFailure, err
 	}
-	if len(device.Peers) == 0 {
-		return nxDomain(p.zone, w, r)
-	}
 
 	// setup our reply message
 	m := new(dns.Msg)
 	m.SetReply(r)
 	m.Authoritative = true
 
+	allPeers := []host{
+		{PublicKey: device.PublicKey, Endpoint: &net.UDPAddr{Port: device.ListenPort, IP: p.wgIP}},
+	}
+	for _, p := range device.Peers {
+		allPeers = append(allPeers, host{
+			PublicKey: p.PublicKey,
+			Endpoint:  p.Endpoint,
+		})
+	}
+
 	switch {
 	// TODO: handle SOA
 	case name == spPrefix && qtype == dns.TypePTR:
-		for _, peer := range device.Peers {
+		for _, peer := range allPeers {
 			if peer.Endpoint == nil {
 				continue
 			}
@@ -93,39 +107,21 @@ func (p *WGSD) ServeDNS(ctx context.Context, w dns.ResponseWriter,
 		}
 		w.WriteMsg(m) // nolint: errcheck
 		return dns.RcodeSuccess, nil
+	case len(name) != serviceInstanceLen && qtype == dns.TypeSRV:
+		return p.sendSRV(m, w, r, allPeers[0])
 	case len(name) == serviceInstanceLen && qtype == dns.TypeSRV:
 		pubKey := name[:keyLen]
-		for _, peer := range device.Peers {
+		for _, peer := range allPeers {
 			if strings.EqualFold(
 				base32.StdEncoding.EncodeToString(peer.PublicKey[:]), pubKey) {
-				endpoint := peer.Endpoint
-				hostRR := getHostRR(pubKey, p.zone, endpoint)
-				if hostRR == nil {
-					return nxDomain(p.zone, w, r)
-				}
-				m.Extra = append(m.Extra, hostRR)
-				m.Answer = append(m.Answer, &dns.SRV{
-					Hdr: dns.RR_Header{
-						Name:   state.Name(),
-						Rrtype: dns.TypeSRV,
-						Class:  dns.ClassINET,
-						Ttl:    0,
-					},
-					Priority: 0,
-					Weight:   0,
-					Port:     uint16(endpoint.Port),
-					Target: fmt.Sprintf("%s.%s",
-						strings.ToLower(pubKey), p.zone),
-				})
-				w.WriteMsg(m) // nolint: errcheck
-				return dns.RcodeSuccess, nil
+				return p.sendSRV(m, w, r, peer)
 			}
 		}
 		return nxDomain(p.zone, w, r)
 	case len(name) == keyLen+1 && (qtype == dns.TypeA ||
 		qtype == dns.TypeAAAA):
 		pubKey := name[:keyLen]
-		for _, peer := range device.Peers {
+		for _, peer := range allPeers {
 			if strings.EqualFold(
 				base32.StdEncoding.EncodeToString(peer.PublicKey[:]), pubKey) {
 				endpoint := peer.Endpoint
@@ -176,6 +172,32 @@ func getHostRR(pubKey, zone string, endpoint *net.UDPAddr) dns.RR {
 	}
 }
 
+func (p *WGSD) sendSRV(m *dns.Msg, w dns.ResponseWriter, r *dns.Msg, peer host) (int, error) {
+	state := request.Request{W: w, Req: r}
+	pubKey := base32.StdEncoding.EncodeToString(peer.PublicKey[:])
+	endpoint := peer.Endpoint
+	hostRR := getHostRR(pubKey, p.zone, endpoint)
+	if hostRR == nil {
+		return nxDomain(p.zone, w, r)
+	}
+	m.Extra = append(m.Extra, hostRR)
+	m.Answer = append(m.Answer, &dns.SRV{
+		Hdr: dns.RR_Header{
+			Name:   state.Name(),
+			Rrtype: dns.TypeSRV,
+			Class:  dns.ClassINET,
+			Ttl:    0,
+		},
+		Priority: 0,
+		Weight:   0,
+		Port:     uint16(endpoint.Port),
+		Target: fmt.Sprintf("%s.%s",
+			strings.ToLower(pubKey), p.zone),
+	})
+	w.WriteMsg(m) // nolint: errcheck
+	return dns.RcodeSuccess, nil
+}
+
 func nxDomain(zone string, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	m := new(dns.Msg)
 	m.SetReply(r)