Split part of DNSServer.Start() to a separate ActivateAndServe()

Specifically, move the part that blocks, and call that as necessary.
This means Start() can run on the caller's goroutine and avoid race conditions.

nameserver/server.go

@@ -218,7 +218,10 @@ func (s *DNSServer) Start() error {
 	s.tcpSrv = &dns.Server{Listener: l, Handler: s.createMux(protTCP), ReadTimeout: s.readTimeout}
 
 	s.listenersWg.Add(2)
+	return nil
+}
 
+func (s *DNSServer) ActivateAndServe() {
 	go func() {
 		defer s.listenersWg.Done()
 
@@ -241,7 +244,6 @@ func (s *DNSServer) Start() error {
 	s.listenersWg.Wait()
 
 	Info.Printf("[dns] Server exiting...")
-	return nil
 }
 
 // Return status string

nameserver/server_cache_test.go

@@ -69,7 +69,9 @@ func TestServerDbCacheInvalidation(t *testing.T) {
 		MaxAnswers:        4,
 	})
 	wt.AssertNoErr(t, err)
-	go srv.Start()
+	err = srv.Start()
+	wt.AssertNoErr(t, err)
+	go srv.ActivateAndServe()
 	defer srv.Stop()
 	time.Sleep(100 * time.Millisecond) // Allow server goroutine to start
 
@@ -202,7 +204,9 @@ func TestServerCacheExpiration(t *testing.T) {
 		CacheNegLocalTTL:  negativeLocalTTL,
 	})
 	wt.AssertNoErr(t, err)
-	go srv.Start()
+	err = srv.Start()
+	wt.AssertNoErr(t, err)
+	go srv.ActivateAndServe()
 	defer srv.Stop()
 	time.Sleep(100 * time.Millisecond) // Allow server goroutine to start
 
@@ -287,7 +291,9 @@ func TestServerCacheRefresh(t *testing.T) {
 		MaxAnswers:        4,
 	})
 	wt.AssertNoErr(t, err)
-	go srv.Start()
+	err = srv.Start()
+	wt.AssertNoErr(t, err)
+	go srv.ActivateAndServe()
 	defer srv.Stop()
 	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
 

nameserver/server_test.go

@@ -89,7 +89,9 @@ func TestUDPDNSServer(t *testing.T) {
 		ListenReadTimeout: testSocketTimeout,
 	})
 	wt.AssertNoErr(t, err)
-	go srv.Start()
+	err = srv.Start()
+	wt.AssertNoErr(t, err)
+	go srv.ActivateAndServe()
 	defer srv.Stop()
 	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
 
@@ -195,7 +197,9 @@ func TestTCPDNSServer(t *testing.T) {
 		ListenReadTimeout: testSocketTimeout,
 	})
 	wt.AssertNoErr(t, err)
-	go srv.Start()
+	err = srv.Start()
+	wt.AssertNoErr(t, err)
+	go srv.ActivateAndServe()
 	defer srv.Stop()
 	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
 

prog/weavedns/main.go

@@ -182,4 +182,5 @@ func main() {
 	if err != nil {
 		Error.Fatal("[main] Failed to start the WeaveDNS server: ", err)
 	}
+	srv.ActivateAndServe()
 }