netcheck, stunner: reduce log spam

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/netcheck.go

@@ -19,7 +19,7 @@ func runNetcheck(ctx context.Context, args []string) error {
 	defer cancel()
 	report, err := netcheck.GetReport(ctx, log.Printf)
 	if err != nil {
-		log.Fatal(err)
+		log.Fatalf("netcheck: %v", err)
 	}
 	fmt.Printf("\nReport:\n")
 	fmt.Printf("\t* UDP: %v\n", report.UDP)

netcheck/netcheck.go

@@ -91,7 +91,6 @@ func GetReport(ctx context.Context, logf logger.Logf) (*Report, error) {
 				logf("ReadFrom: unexpected addr %T", addr)
 				continue
 			}
-			logf("Packet from %v: %q", ua, buf[:n])
 			s.Receive(buf[:n], ua)
 		}
 
@@ -120,7 +119,9 @@ func GetReport(ctx context.Context, logf logger.Logf) (*Report, error) {
 	}
 
 	err = grp.Wait()
-	logf("stunner.Run: %v", err)
+	if err != nil {
+		return nil, err
+	}
 
 	mu.Lock()
 	defer mu.Unlock() // unnecessary, but feels weird without

stunner/stunner.go

@@ -112,7 +112,6 @@ func (s *Stunner) Receive(p []byte, fromAddr *net.UDPAddr) {
 	session := s.sessions[r.server]
 	if session != nil {
 		host := net.JoinHostPort(net.IP(addr).String(), fmt.Sprint(port))
-		s.logf("STUN server %s reports public endpoint %s after %v", r.server, host, d)
 		s.Endpoint(r.server, host, d)
 		session.cancel()
 	}
@@ -127,6 +126,10 @@ func (s *Stunner) resolver() *net.Resolver {
 
 // Run starts a Stunner and blocks until all servers either respond
 // or are tried multiple times and timeout.
+//
+// TODO: this always returns success now. It should return errors
+// if certain servers are unavailable probably. Or if all are.
+// Or some configured threshold are.
 func (s *Stunner) Run(ctx context.Context) error {
 	s.sessions = map[string]*session{}
 	for _, server := range s.Servers {