lndclient: cache node info on connect

lndclient/lnd_services.go

@@ -52,6 +52,8 @@ type LndServices struct {
 	Versioner     VersionerClient
 
 	ChainParams *chaincfg.Params
+	NodeAlias   string
+	NodePubkey  [33]byte
 
 	macaroons *macaroonPouch
 }
@@ -133,7 +135,9 @@ func NewLndServices(cfg *LndServicesConfig) (*GrpcLndServices, error) {
 	if err != nil {
 		return nil, err
 	}
-	err = checkLndCompatibility(conn, chainParams, readonlyMac, cfg.Network)
+	nodeAlias, nodeKey, err := checkLndCompatibility(
+		conn, chainParams, readonlyMac, cfg.Network,
+	)
 	if err != nil {
 		return nil, err
 	}
@@ -189,6 +193,8 @@ func NewLndServices(cfg *LndServicesConfig) (*GrpcLndServices, error) {
 			Router:        routerClient,
 			Versioner:     versionerClient,
 			ChainParams:   chainParams,
+			NodeAlias:     nodeAlias,
+			NodePubkey:    nodeKey,
 			macaroons:     macaroons,
 		},
 		cleanup: cleanup,
@@ -210,7 +216,19 @@ func (s *GrpcLndServices) Close() {
 // checkLndCompatibility makes sure the connected lnd instance is running on the
 // correct network.
 func checkLndCompatibility(conn *grpc.ClientConn, chainParams *chaincfg.Params,
-	readonlyMac serializedMacaroon, network string) error {
+	readonlyMac serializedMacaroon, network string) (string, [33]byte,
+	error) {
+
+	// onErr is a closure that simplifies returning multiple values in the
+	// error case.
+	onErr := func(err error) (string, [33]byte, error) {
+		closeErr := conn.Close()
+		if closeErr != nil {
+			log.Errorf("Error closing lnd connection: %v", closeErr)
+		}
+
+		return "", [33]byte{}, err
+	}
 
 	// We use our own client with a readonly macaroon here, because we know
 	// that's all we need for the checks.
@@ -220,17 +238,18 @@ func checkLndCompatibility(conn *grpc.ClientConn, chainParams *chaincfg.Params,
 	// for lnd matches our expected network.
 	info, err := lightningClient.GetInfo(context.Background())
 	if err != nil {
-		conn.Close()
-		return fmt.Errorf("unable to get info for lnd "+
-			"node: %v", err)
+		err := fmt.Errorf("unable to get info for lnd node: %v", err)
+		return onErr(err)
 	}
 	if network != info.Network {
-		conn.Close()
-		return fmt.Errorf("network mismatch with connected lnd "+
-			"node, got '%s', wanted '%s'", info.Network, network)
-
+		err := fmt.Errorf("network mismatch with connected lnd node, "+
+			"wanted '%s', got '%s'", network, info.Network)
+		return onErr(err)
 	}
-	return nil
+
+	// Return the static part of the info we just queried from the node so
+	// it can be cached for later use.
+	return info.Alias, info.IdentityPubkey, nil
 }
 
 var (

test/lnd_services_mock.go

@@ -1,6 +1,7 @@
 package test
 
 import (
+	"context"
 	"errors"
 	"sync"
 	"time"
@@ -77,6 +78,11 @@ func NewMockLnd() *LndMockServices {
 	router.lnd = &lnd
 	signer.lnd = &lnd
 
+	// Also simulate the cached info that is loaded on startup.
+	info, _ := lightningClient.GetInfo(context.Background())
+	lnd.LndServices.NodeAlias = info.Alias
+	lnd.LndServices.NodePubkey = info.IdentityPubkey
+
 	lnd.WaitForFinished = func() {
 		chainNotifier.WaitForFinished()
 		lightningClient.WaitForFinished()