MDNS registry fix for users on VPNs (#1759)

* filter out unsolicited responses
* send to local ip in case
* allow ip func to be passed in. add option for sending to 0.0.0.0

util/mdns/client.go

@@ -34,6 +34,7 @@ type ServiceEntry struct {
 
 // complete is used to check if we have all the info we need
 func (s *ServiceEntry) complete() bool {
+
 	return (len(s.AddrV4) > 0 || len(s.AddrV6) > 0 || len(s.Addr) > 0) && s.Port != 0 && s.hasTXT
 }
 
@@ -347,15 +348,21 @@ func (c *client) query(params *QueryParam) error {
 		select {
 		case resp := <-msgCh:
 			inp := messageToEntry(resp, inprogress)
+
 			if inp == nil {
 				continue
 			}
+			if len(resp.Question) == 0 || resp.Question[0].Name != m.Question[0].Name {
+				// discard anything which we've not asked for
+				continue
+			}
 
 			// Check if this entry is complete
 			if inp.complete() {
 				if inp.sent {
 					continue
 				}
+
 				inp.sent = true
 				select {
 				case params.Entries <- inp: