multi: split out LND connection from rpcProxy

Remove the responsibility of creating an LND connection from the
rpcProxy and instead let the main LightningTerminal struct handle it.
All the lnd-connection specific functions are also moved into their own
file.

Author: ellemouton

lnd_connection.go

@@ -0,0 +1,85 @@
+package terminal
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net"
+
+	grpcProxy "github.com/mwitkow/grpc-proxy/proxy"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/backoff"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/test/bufconn"
+)
+
+// connectLND sets up LiT's LND connection.
+func connectLND(cfg *Config, bufListener *bufconn.Listener) (*grpc.ClientConn,
+	error) {
+
+	if cfg.lndRemote {
+		host, _, tlsPath, _, _ := cfg.lndConnectParams()
+		return dialBackend("lnd", host, tlsPath)
+	}
+
+	// If LND is running in integrated mode, then we use a bufconn to
+	// connect to lnd in integrated mode.
+	return dialBufConnBackend(bufListener)
+}
+
+// dialBackend connects to a gRPC backend through the given address and uses the
+// given TLS certificate to authenticate the connection.
+func dialBackend(name, dialAddr, tlsCertPath string) (*grpc.ClientConn, error) {
+	tlsConfig, err := credentials.NewClientTLSFromFile(tlsCertPath, "")
+	if err != nil {
+		return nil, fmt.Errorf("could not read %s TLS cert %s: %v",
+			name, tlsCertPath, err)
+	}
+
+	opts := []grpc.DialOption{
+		// From the grpcProxy doc: This codec is *crucial* to the
+		// functioning of the proxy.
+		grpc.WithCodec(grpcProxy.Codec()), // nolint
+		grpc.WithTransportCredentials(tlsConfig),
+		grpc.WithDefaultCallOptions(maxMsgRecvSize),
+		grpc.WithConnectParams(grpc.ConnectParams{
+			Backoff:           backoff.DefaultConfig,
+			MinConnectTimeout: defaultConnectTimeout,
+		}),
+	}
+
+	log.Infof("Dialing %s gRPC server at %s", name, dialAddr)
+	cc, err := grpc.Dial(dialAddr, opts...)
+	if err != nil {
+		return nil, fmt.Errorf("failed dialing %s backend: %v", name,
+			err)
+	}
+	return cc, nil
+}
+
+// dialBufConnBackend dials an in-memory connection to an RPC listener and
+// ignores any TLS certificate mismatches.
+func dialBufConnBackend(listener *bufconn.Listener) (*grpc.ClientConn, error) {
+	tlsConfig := credentials.NewTLS(&tls.Config{
+		InsecureSkipVerify: true,
+	})
+
+	opts := []grpc.DialOption{
+		grpc.WithContextDialer(
+			func(context.Context, string) (net.Conn, error) {
+				return listener.Dial()
+			},
+		),
+		// From the grpcProxy doc: This codec is *crucial* to the
+		// functioning of the proxy.
+		grpc.WithCodec(grpcProxy.Codec()), // nolint
+		grpc.WithTransportCredentials(tlsConfig),
+		grpc.WithDefaultCallOptions(maxMsgRecvSize),
+		grpc.WithConnectParams(grpc.ConnectParams{
+			Backoff:           backoff.DefaultConfig,
+			MinConnectTimeout: defaultConnectTimeout,
+		}),
+	}
+
+	return grpc.Dial("", opts...)
+}

rpc_proxy.go

@@ -2,12 +2,10 @@ package terminal
 
 import (
 	"context"
-	"crypto/tls"
 	"encoding/base64"
 	"encoding/hex"
 	"fmt"
 	"io/ioutil"
-	"net"
 	"net/http"
 	"strings"
 	"sync/atomic"
@@ -21,12 +19,9 @@ import (
 	"github.com/lightningnetwork/lnd/macaroons"
 	grpcProxy "github.com/mwitkow/grpc-proxy/proxy"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/backoff"
 	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
-	"google.golang.org/grpc/test/bufconn"
 	"gopkg.in/macaroon.v2"
 )
 
@@ -65,7 +60,7 @@ func (e *proxyErr) Unwrap() error {
 // component.
 func newRpcProxy(cfg *Config, validator macaroons.MacaroonValidator,
 	superMacValidator session.SuperMacaroonValidator,
-	permsMgr *perms.Manager, bufListener *bufconn.Listener) *rpcProxy {
+	permsMgr *perms.Manager) *rpcProxy {
 
 	// The gRPC web calls are protected by HTTP basic auth which is defined
 	// by base64(username:password). Because we only have a password, we
@@ -85,7 +80,6 @@ func newRpcProxy(cfg *Config, validator macaroons.MacaroonValidator,
 		permsMgr:          permsMgr,
 		macValidator:      validator,
 		superMacValidator: superMacValidator,
-		bufListener:       bufListener,
 	}
 	p.grpcServer = grpc.NewServer(
 		// From the grpxProxy doc: This codec is *crucial* to the
@@ -162,7 +156,6 @@ type rpcProxy struct {
 
 	macValidator      macaroons.MacaroonValidator
 	superMacValidator session.SuperMacaroonValidator
-	bufListener       *bufconn.Listener
 
 	superMacaroon string
 
@@ -176,21 +169,9 @@ type rpcProxy struct {
 }
 
 // Start creates initial connection to lnd.
-func (p *rpcProxy) Start() error {
+func (p *rpcProxy) Start(lndConn *grpc.ClientConn) error {
 	var err error
-
-	// Setup the connection to lnd.
-	host, _, tlsPath, _, _ := p.cfg.lndConnectParams()
-
-	// We use a bufconn to connect to lnd in integrated mode.
-	if p.cfg.LndMode == ModeIntegrated {
-		p.lndConn, err = dialBufConnBackend(p.bufListener)
-	} else {
-		p.lndConn, err = dialBackend("lnd", host, tlsPath)
-	}
-	if err != nil {
-		return fmt.Errorf("could not dial lnd: %v", err)
-	}
+	p.lndConn = lndConn
 
 	// Make sure we can connect to all the daemons that are configured to be
 	// running in remote mode.
@@ -242,13 +223,6 @@ func (p *rpcProxy) hasStarted() bool {
 func (p *rpcProxy) Stop() error {
 	p.grpcServer.Stop()
 
-	if p.lndConn != nil {
-		if err := p.lndConn.Close(); err != nil {
-			log.Errorf("Error closing lnd connection: %v", err)
-			return err
-		}
-	}
-
 	if p.faradayConn != nil {
 		if err := p.faradayConn.Close(); err != nil {
 			log.Errorf("Error closing faraday connection: %v", err)
@@ -681,68 +655,6 @@ func (p *rpcProxy) convertSuperMacaroon(ctx context.Context, macHex string,
 	return nil, nil
 }
 
-// dialBufConnBackend dials an in-memory connection to an RPC listener and
-// ignores any TLS certificate mismatches.
-func dialBufConnBackend(listener *bufconn.Listener) (*grpc.ClientConn, error) {
-	tlsConfig := credentials.NewTLS(&tls.Config{
-		InsecureSkipVerify: true,
-	})
-	conn, err := grpc.Dial(
-		"",
-		grpc.WithContextDialer(
-			func(context.Context, string) (net.Conn, error) {
-				return listener.Dial()
-			},
-		),
-		grpc.WithTransportCredentials(tlsConfig),
-
-		// From the grpcProxy doc: This codec is *crucial* to the
-		// functioning of the proxy.
-		grpc.WithCodec(grpcProxy.Codec()), // nolint
-		grpc.WithTransportCredentials(tlsConfig),
-		grpc.WithDefaultCallOptions(maxMsgRecvSize),
-		grpc.WithConnectParams(grpc.ConnectParams{
-			Backoff:           backoff.DefaultConfig,
-			MinConnectTimeout: defaultConnectTimeout,
-		}),
-	)
-
-	return conn, err
-}
-
-// dialBackend connects to a gRPC backend through the given address and uses the
-// given TLS certificate to authenticate the connection.
-func dialBackend(name, dialAddr, tlsCertPath string) (*grpc.ClientConn, error) {
-	var opts []grpc.DialOption
-	tlsConfig, err := credentials.NewClientTLSFromFile(tlsCertPath, "")
-	if err != nil {
-		return nil, fmt.Errorf("could not read %s TLS cert %s: %v",
-			name, tlsCertPath, err)
-	}
-
-	opts = append(
-		opts,
-
-		// From the grpcProxy doc: This codec is *crucial* to the
-		// functioning of the proxy.
-		grpc.WithCodec(grpcProxy.Codec()), // nolint
-		grpc.WithTransportCredentials(tlsConfig),
-		grpc.WithDefaultCallOptions(maxMsgRecvSize),
-		grpc.WithConnectParams(grpc.ConnectParams{
-			Backoff:           backoff.DefaultConfig,
-			MinConnectTimeout: defaultConnectTimeout,
-		}),
-	)
-
-	log.Infof("Dialing %s gRPC server at %s", name, dialAddr)
-	cc, err := grpc.Dial(dialAddr, opts...)
-	if err != nil {
-		return nil, fmt.Errorf("failed dialing %s backend: %v", name,
-			err)
-	}
-	return cc, nil
-}
-
 // readMacaroon tries to read the macaroon file at the specified path and create
 // gRPC dial options from it.
 func readMacaroon(macPath string) ([]byte, error) {

terminal.go

@@ -160,6 +160,7 @@ type LightningTerminal struct {
 	wg       sync.WaitGroup
 	errQueue *queue.ConcurrentQueue[error]
 
+	lndConn     *grpc.ClientConn
 	lndClient   *lndclient.GrpcLndServices
 	basicClient lnrpc.LightningClient
 
@@ -244,7 +245,7 @@ func (g *LightningTerminal) Run() error {
 	g.loopServer = loopd.New(g.cfg.Loop, nil)
 	g.poolServer = pool.NewServer(g.cfg.Pool)
 	g.rpcProxy = newRpcProxy(
-		g.cfg, g, g.validateSuperMacaroon, g.permsMgr, bufRpcListener,
+		g.cfg, g, g.validateSuperMacaroon, g.permsMgr,
 	)
 	g.accountService, err = accounts.NewService(
 		filepath.Dir(g.cfg.MacaroonPath), g.errQueue.ChanIn(),
@@ -436,11 +437,17 @@ func (g *LightningTerminal) Run() error {
 		}
 	}()
 
+	// Connect to LND.
+	g.lndConn, err = connectLND(g.cfg, bufRpcListener)
+	if err != nil {
+		return fmt.Errorf("could not connect to LND: %v", err)
+	}
+
 	// Now start the RPC proxy that will handle all incoming gRPC, grpc-web
 	// and REST requests. We also start the main web server that dispatches
 	// requests either to the static UI file server or the RPC proxy. This
 	// makes it possible to unlock lnd through the UI.
-	if err := g.rpcProxy.Start(); err != nil {
+	if err := g.rpcProxy.Start(g.lndConn); err != nil {
 		return fmt.Errorf("error starting lnd gRPC proxy server: %v",
 			err)
 	}
@@ -1178,6 +1185,13 @@ func (g *LightningTerminal) shutdown() error {
 		}
 	}
 
+	if g.lndConn != nil {
+		if err := g.lndConn.Close(); err != nil {
+			log.Errorf("Error closing lnd connection: %v", err)
+			returnErr = err
+		}
+	}
+
 	if g.httpServer != nil {
 		if err := g.httpServer.Close(); err != nil {
 			log.Errorf("Error stopping UI server: %v", err)