Lnd manager

app/lightning.js

@@ -4,53 +4,109 @@ const fs = require("fs");
 const logger = require("winston");
 const debug = require("debug")("lncliweb:lightning");
 
-// expose the routes to our app with module.exports
-module.exports = function (protoPath, lndHost, lndCertPath, macaroonPath) {
+const LightningError = Object.freeze({
+    "WALLET_LOCKED": "WALLET_LOCKED",
+    "NODE_UNREACHABLE": "NODE_UNREACHABLE",
+    "UNCATEGORIZED": "UNCATEGORIZED"
+});
 
-	process.env.GRPC_SSL_CIPHER_SUITES = "HIGH+ECDSA";
 
-	const lnrpcDescriptor = grpc.load(protoPath);
+/**
+ * Defines a wrapper around the Lightning gRPC API, with error support, retry, and async API.
+ * Every call towards `Lightning` should be handled through the `Call` API.
+ */
+class LightningManager {
 
-	if (lndCertPath) {
+    getActiveClient() {
+        if (!this.activeClient) {
+            logger.info("Recreating active client");
+            this.credentials = this.generateCredentials(this.lndCert, {macaroonPath: this.macaroonPath});
+            this.activeClient = new this.lnrpcDescriptor.lnrpc.Lightning(this.lndHost, this.credentials);
+        }
+        return this.activeClient;
+    }
 
-		if (fs.existsSync(lndCertPath)) {
+    generateCredentials(lndCert, options) {
+	let credentials = grpc.credentials.createSsl(lndCert);
 
-			const lndCert = fs.readFileSync(lndCertPath);
-			const sslCreds = grpc.credentials.createSsl(lndCert);
+        // If macaroon path was specified load credentials using macaroon metadata.
+        if (options.macaroonPath) {
+            if (fs.existsSync(options.macaroonPath)) {
+                let macaroonCreds = grpc.credentials.createFromMetadataGenerator(function (args, callback) {
+                    let adminMacaroon = fs.readFileSync(options.macaroonPath);
+                    let metadata = new grpc.Metadata();
+                    metadata.add("macaroon", adminMacaroon.toString("hex"));
+                    callback(null, metadata);
+                });
+                credentials = grpc.credentials.combineChannelCredentials(credentials, macaroonCreds);
+            } else {
+                logger.error("The specified macaroon file "+ options.macaroonPath + " was not found.\n" + 
+                             "Please add the missing lnd macaroon file or update/remove the path in the application configuration.");
+                process.exit(1);
+            }
+        }
 
-			var credentials;
-			if (macaroonPath) {
-				if (fs.existsSync(macaroonPath)) {
-					var macaroonCreds = grpc.credentials.createFromMetadataGenerator(function (args, callback) {
-						const adminMacaroon = fs.readFileSync(macaroonPath);
-						const metadata = new grpc.Metadata();
-						metadata.add("macaroon", adminMacaroon.toString("hex"));
-						callback(null, metadata);
-					});
-					credentials = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
-				} else {
-					logger.error("The specified macaroon file \"" + macaroonPath + "\" was not found.\n"
-							+ "Please add the missing lnd macaroon file or update/remove the path in the application configuration.");
-					process.exit(1);
-				}
-			} else {
-				credentials = sslCreds;
-			}
+        return credentials;
+    }
 
-			return new lnrpcDescriptor.lnrpc.Lightning(lndHost, credentials);
+    /**
+     * @constructor
+     * @param {string} protoPath - the path to the `rpc.proto` file that defined the `Lightning` RPC interface
+     * @param {string} lndHost - the host and port of the LND node (ex. "locahost:10003")
+     * @param {string} lndCertPath - the path to the SSL certificate used by LND 
+     * @param {?string} macaroonPath - the path to the macarron file to use. Can be `null` if no macaroon should be used.
+     */
+    constructor(protoPath, lndHost, lndCertPath, macaroonPath) {
+        process.env.GRPC_SSL_CIPHER_SUITES = "HIGH+ECDSA";
 
-		} else {
+	if (!fs.existsSync(lndCertPath)) {
+            logger.error("Required lnd certificate path missing from application configuration.");
+            process.exit(1);
+        }
 
-			logger.error("The specified lnd certificate file \"" + lndCertPath + "\" was not found.\n"
-					+ "Please add the missing lnd certificate file or update the path in the application configuration.");
-			process.exit(1);
+        // Define credentials for SSL certificate generated by LND, and active client
+        this.lndHost = lndHost;
+	this.lndCert = fs.readFileSync(lndCertPath);
+        this.lnrpcDescriptor = grpc.load(protoPath);
+	this.macaroonPath = macaroonPath;
+        this.activeClient = null;
+    }
 
-		}
+    /*
+     * Calls a Lightning gRPC method.
+     * @param {string} method - the gRPC method to call (ex. "getInfo")
+     * @param {Object} parameters - optional key/value parameters to supply for the API call
+     * @returns {Promise} - if successful, response if an Object containing API result payload, otherwise it will fail
+       with a LightningError.
+     */
+    async call(method, parameters) {
+        return new Promise((resolve, reject) => {
+            let activeClient = this.getActiveClient();
+            activeClient[method](parameters, (err, response) => {
+                if (err) {
 
-	} else {
+                    // drop active client, so that it can be recreated
+                    this.activeClient = null;
 
-		logger.error("Required lnd certificate path missing from application configuration.");
-		process.exit(1);
+                    switch(err.code) {
+                        case grpc.status.UNIMPLEMENTED:
+                            reject(LightningError.WALLET_LOCKED);
+                            break;
+                        case grpc.status.UNAVAILABLE:
+                            reject(LightningError.NODE_UNREACHABLE);
+                            break;
+                        default:
+                            logger.error("Unrecognized gRPC error: " + err);
+                            reject(LightningError.UNCATEGORIZED);
+                    }
+                } else {
+                    logger.debug(method + ":", response);
+                    resolve(response);
+                }
+            });
+        });
+    }
+}
 
-	}
-};
+
+module.exports = LightningManager;

app/lnd.js

@@ -17,7 +17,7 @@ module.exports = function (lightning) {
 			logger.debug("Lnd invoices subscription stream already opened.");
 		} else {
 			logger.debug("Opening lnd invoices subscription stream...");
-			lndInvoicesStream = lightning.subscribeInvoices({});
+			lndInvoicesStream = lightning.getActiveClient().subscribeInvoices({});
 			logger.debug("Lnd invoices subscription stream opened.");
 			lndInvoicesStream.on("data", function (data) {
 				logger.debug("SubscribeInvoices Data", data);

app/lnsignauth.js

@@ -23,7 +23,7 @@ module.exports = function (lightning, config) {
 
 		debug("sessionID.signature:", user.name);
 
-		lightning.verifyMessage({ msg: Buffer.from(req.sessionID, "utf8"), signature: user.name }, function (err, response) {
+		lightning.getActiveClient().verifyMessage({ msg: Buffer.from(req.sessionID, "utf8"), signature: user.name }, function (err, response) {
 			if (err) {
 				debug("VerifyMessage Error:", err);
 				unauthorized(res);

app/lnsignpayreqauth.js

@@ -28,7 +28,7 @@ module.exports = function (lightning, config) {
 
 		debug("payreq.signature:", user.name);
 
-		lightning.verifyMessage({ msg: Buffer.from(config.defaultAuthPayReq, "utf8"), signature: user.name }, function (err, verifMsgResponse) {
+		lightning.getActiveClient().verifyMessage({ msg: Buffer.from(config.defaultAuthPayReq, "utf8"), signature: user.name }, function (err, verifMsgResponse) {
 			if (err) {
 				debug("VerifyMessage Error:", err);
 				unauthorized(res);