enable relay by default in New

options.go

@@ -201,15 +201,25 @@ func AddrsFactory(factory config.AddrsFactory) Option {
 	}
 }
 
-// EnableRelay configures libp2p to enable the relay transport.
+// EnableRelay configures libp2p to enable the relay transport with configuration options.
 func EnableRelay(options ...circuit.RelayOpt) Option {
 	return func(cfg *Config) error {
+		cfg.RelayCustom = true
 		cfg.Relay = true
 		cfg.RelayOpts = options
 		return nil
 	}
 }
 
+// DisableRelay configures libp2p to disable the relay transport
+func DisableRelay() Option {
+	return func(cfg *Config) error {
+		cfg.RelayCustom = true
+		cfg.Relay = false
+		return nil
+	}
+}
+
 // FilterAddresses configures libp2p to never dial nor accept connections from
 // the given addresses.
 func FilterAddresses(addrs ...*net.IPNet) Option {
@@ -245,9 +255,15 @@ func NATManager(nm config.NATManagerC) Option {
 // NoListenAddrs will configure libp2p to not listen by default.
 //
 // This will both clear any configured listen addrs and prevent libp2p from
-// applying the default listen address option.
+// applying the default listen address option. It also disables relay, unless the
+// user explicitly specifies with an option, as the transport creates an implicit
+// listen address that would make the node diable through any relay it was connected to.
 var NoListenAddrs = func(cfg *Config) error {
 	cfg.ListenAddrs = []ma.Multiaddr{}
+	if !cfg.RelayCustom {
+		cfg.RelayCustom = true
+		cfg.Relay = false
+	}
 	return nil
 }