Allow not to limit bandwidth in LAN (fixes #1336)

cmd/syncthing/main.go

@@ -115,6 +115,7 @@ var (
 	externalPort   int
 	igd            *upnp.IGD
 	cert           tls.Certificate
+	lans           []*net.IPNet
 )
 
 const (
@@ -494,6 +495,10 @@ func syncthingMain() {
 		readRateLimit = ratelimit.NewBucketWithRate(float64(1000*opts.MaxRecvKbps), int64(5*1000*opts.MaxRecvKbps))
 	}
 
+	if opts.MaxRecvKbps > 0 || opts.MaxSendKbps > 0 {
+		lans, _ = osutil.GetLans()
+	}
+
 	dbFile := filepath.Join(confDir, "index")
 	dbOpts := &opt.Options{OpenFilesCacheCapacity: 100}
 	ldb, err := leveldb.OpenFile(dbFile, dbOpts)