ipn/ipnstate: include DNSName in tailscale status --json output

ipn/ipnstate/ipnstate.go

@@ -45,6 +45,7 @@ func (s *Status) Peers() []key.Public {
 type PeerStatus struct {
 	PublicKey key.Public
 	HostName  string // HostInfo's Hostname (not a DNS name or necessarily unique)
+	DNSName   string
 	OS        string // HostInfo.OS
 	UserID    tailcfg.UserID
 
@@ -166,6 +167,9 @@ func (sb *StatusBuilder) AddPeer(peer key.Public, st *PeerStatus) {
 	if v := st.HostName; v != "" {
 		e.HostName = v
 	}
+	if v := st.DNSName; v != "" {
+		e.DNSName = v
+	}
 	if v := st.Relay; v != "" {
 		e.Relay = v
 	}

ipn/local.go

@@ -166,6 +166,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 				UserID:       p.User,
 				TailAddr:     tailAddr,
 				HostName:     p.Hostinfo.Hostname,
+				DNSName:      p.Name,
 				OS:           p.Hostinfo.OS,
 				KeepAlive:    p.KeepAlive,
 				Created:      p.Created,