Fix Reach services discovery

- Use github.com/grandcat/zeroconf lib instead of github.com/oleksandr/bonjour

emlid/discovery.go

@@ -1,65 +1,52 @@
 package emlid
 
 import (
+	"context"
 	"net"
 	"sync"
-	"time"
 
-	"github.com/oleksandr/bonjour"
+	"github.com/grandcat/zeroconf"
 )
 
 // Service is a ReachRS service discovered via MDNS-SD
 type Service struct {
 	Name   string
-	AddrV4 net.IP
+	AddrV4 *net.IP
 	Port   int
 }
 
-// Discover tries to discover ReachRS services on the local network via MDNS-SD
-func Discover(timeout time.Duration) ([]Service, error) {
+// Discover tries to discover ReachRS services on the local network via mDNS-SD
+func Discover(ctx context.Context) ([]Service, error) {
 
 	var wg sync.WaitGroup
 
 	wg.Add(1)
 
-	resolver, err := bonjour.NewResolver(nil)
+	resolver, err := zeroconf.NewResolver(nil)
 	if err != nil {
 		return nil, err
 	}
 
 	services := make([]Service, 0)
-	entries := make(chan *bonjour.ServiceEntry)
-	timer := time.NewTimer(timeout)
-	defer timer.Stop()
-
-	stop := func() {
-		resolver.Exit <- true
-		wg.Done()
-	}
+	entries := make(chan *zeroconf.ServiceEntry)
 
 	go func() {
-		for {
-			select {
-
-			case e, ok := <-entries:
-				if !ok {
-					stop()
-					return
-				}
-				services = append(services, Service{
-					Name:   e.Instance,
-					AddrV4: e.AddrIPv4,
-					Port:   e.Port,
-				})
-
-			case <-timer.C:
-				stop()
-				return
+		for e := range entries {
+			var addr *net.IP
+			if len(e.AddrIPv4) > 0 {
+				addr = &e.AddrIPv4[0]
 			}
+			srv := Service{
+				Name:   e.Instance,
+				AddrV4: addr,
+				Port:   e.Port,
+			}
+			services = append(services, srv)
 		}
+		wg.Done()
 	}()
 
-	if err = resolver.Browse("_reach._tcp", ".local", entries); err != nil {
+	if err = resolver.Browse(ctx, "_reach._tcp", ".local", entries); err != nil {
 		return nil, err
 	}
 

emlid/discovery_test.go

@@ -1,6 +1,7 @@
 package emlid
 
 import (
+	"context"
 	"testing"
 	"time"
 )
@@ -11,7 +12,10 @@ func TestDiscovery(t *testing.T) {
 		t.Skip("To run this test, use: go test -discovery-integration")
 	}
 
-	services, err := Discover(3 * time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	services, err := Discover(ctx)
 	if err != nil {
 		t.Fatal(err)
 	}