Lnd: Add BufListener to ListenerCfg for in-memory RPC calls to LND

lnd.go

@@ -173,14 +173,19 @@ type ListenerWithSignal struct {
 
 	// Ready will be closed by the server listening on Listener.
 	Ready chan struct{}
+
+	// MacChan is an optional way to pass the admin macaroon to the program
+	// that started lnd. The channel should be buffered to avoid lnd being
+	// blocked on sending to the channel.
+	MacChan chan []byte
 }
 
 // ListenerCfg is a wrapper around custom listeners that can be passed to lnd
 // when calling its main method.
 type ListenerCfg struct {
-	// RPCListener can be set to the listener to use for the RPC server. If
-	// nil a regular network listener will be created.
-	RPCListener *ListenerWithSignal
+	// RPCListeners can be set to the listeners to use for the RPC server.
+	// If empty a regular network listener will be created.
+	RPCListeners []*ListenerWithSignal
 
 	// ExternalRPCSubserverCfg is optional and specifies the registration
 	// callback and permissions to register external gRPC subservers.
@@ -325,8 +330,8 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 	// If we have chosen to start with a dedicated listener for the
 	// rpc server, we set it directly.
 	var grpcListeners []*ListenerWithSignal
-	if lisCfg.RPCListener != nil {
-		grpcListeners = []*ListenerWithSignal{lisCfg.RPCListener}
+	if len(lisCfg.RPCListeners) > 0 {
+		grpcListeners = append(grpcListeners, lisCfg.RPCListeners...)
 	} else {
 		// Otherwise we create listeners from the RPCListeners defined
 		// in the config.
@@ -618,6 +623,12 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 			// The channel is buffered by one element so writing
 			// should not block here.
 			walletInitParams.MacResponseChan <- adminMacBytes
+
+			for _, lis := range grpcListeners {
+				if lis.MacChan != nil {
+					lis.MacChan <- adminMacBytes
+				}
+			}
 		}
 
 		// If the user requested a stateless initialization, no macaroon
@@ -679,6 +690,14 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 	// --no-macaroons is used.
 	close(walletInitParams.MacResponseChan)
 
+	// We'll also close all the macaroon channels since lnd is done sending
+	// macaroon data over it.
+	for _, lis := range grpcListeners {
+		if lis.MacChan != nil {
+			close(lis.MacChan)
+		}
+	}
+
 	// With the information parsed from the configuration, create valid
 	// instances of the pertinent interfaces required to operate the
 	// Lightning Network Daemon.

mobile/bindings.go

@@ -94,10 +94,10 @@ func Start(extraArgs string, rpcReady Callback) {
 	// We call the main method with the custom in-memory listener called by
 	// the mobile APIs, such that the grpc server will use it.
 	cfg := lnd.ListenerCfg{
-		RPCListener: &lnd.ListenerWithSignal{
+		RPCListeners: []*lnd.ListenerWithSignal{{
 			Listener: lightningLis,
 			Ready:    rpcListening,
-		},
+		}},
 	}
 
 	// Call the "real" main in a nested manner so the defers will properly