Support for reloading rpc credentials and reconnecting

Fixes #393

Smarter identification of auth type (usernamePassword/cookie); if using cookie auth, watch cookie file for changes and, if seen, reload and attempt rpc reconnect

app.js

@@ -872,8 +872,15 @@ expressApp.onStartup = async () => {
 	}
 }
 
-expressApp.continueStartup = function() {
-	let rpcCred = config.credentials.rpc;
+function connectToRpcServer() {
+	// reload credentials, the main "config.credentials.rpc" can be stale
+	// since the username/password can be sourced from the auth cookie
+	// which changes each startup of bitcoind
+	let credentialsForRpcConnect = config.credentials.loadFreshRpcCredentials();
+
+	debugLog(`RPC Credentials: ${JSON.stringify(utils.obfuscateProperties(credentialsForRpcConnect, ["password"]), null, 4)}`);
+
+	let rpcCred = credentialsForRpcConnect;
 	debugLog(`Connecting to RPC node at [${rpcCred.host}]:${rpcCred.port}`);
 
 	let usernamePassword = `${rpcCred.username}:${rpcCred.password}`;
@@ -910,6 +917,22 @@ expressApp.continueStartup = function() {
 
 	// no timeout RPC client, for long-running commands
 	global.rpcClientNoTimeout = jayson.Client.http(rpcClientNoTimeoutProperties);
+}
+
+expressApp.continueStartup = function() {
+	connectToRpcServer();
+
+	// if using cookie auth, watch for changes to the file and reconnect
+	if (config.credentials.rpc.authType == "cookie") {
+		debugLog(`RPC authentication is cookie based; watching for changes to the auth cookie file...`);
+
+		fs.watchFile(config.credentials.rpc.authCookieFilepath, (curr, prev) => {
+			debugLog(`RPC auth cookie change detected; attempting reconnect...`);
+
+			connectToRpcServer();
+		});
+	}
+
 
 	// default values - after we connect via RPC, we update these
 	global.txindexAvailable = false;

app/config.js

@@ -35,15 +35,6 @@ const currentCoin = process.env.BTCEXP_COIN || "BTC";
 
 const rpcCred = credentials.rpc;
 
-if (rpcCred.cookie && !rpcCred.username && !rpcCred.password && fs.existsSync(rpcCred.cookie)) {
-	console.log(`Loading RPC cookie file: ${rpcCred.cookie}`);
-	
-	[ rpcCred.username, rpcCred.password ] = fs.readFileSync(rpcCred.cookie).toString().split(':', 2);
-	
-	if (!rpcCred.password) {
-		throw new Error(`Cookie file ${rpcCred.cookie} in unexpected format`);
-	}
-}
 
 const cookieSecret = process.env.BTCEXP_COOKIE_SECRET
  || (rpcCred.password && crypto.createHmac('sha256', JSON.stringify(rpcCred))

app/credentials.js

@@ -3,19 +3,58 @@
 const os = require('os');
 const path = require('path');
 const url = require('url');
+const fs = require("fs");
+
+const debug = require("debug");
+const debugLog = debug("btcexp:config");
 
 const btcUri = process.env.BTCEXP_BITCOIND_URI ? url.parse(process.env.BTCEXP_BITCOIND_URI, true) : { query: { } };
 const btcAuth = btcUri.auth ? btcUri.auth.split(':') : [];
 
-module.exports = {
-	rpc: {
+
+
+
+function loadFreshRpcCredentials() {
+	let username = btcAuth[0] || process.env.BTCEXP_BITCOIND_USER;
+	let password = btcAuth[1] || process.env.BTCEXP_BITCOIND_PASS;
+
+	let authCookieFilepath = btcUri.query.cookie || process.env.BTCEXP_BITCOIND_COOKIE || path.join(os.homedir(), '.bitcoin', '.cookie');
+
+	let authType = "usernamePassword";
+
+	if (!username && !password && fs.existsSync(authCookieFilepath)) {
+		authType = "cookie";
+	}
+
+	if (authType == "cookie") {
+		debugLog(`Loading RPC cookie file: ${authCookieFilepath}`);
+		
+		[ username, password ] = fs.readFileSync(authCookieFilepath).toString().trim().split(':', 2);
+		
+		if (!password) {
+			throw new Error(`Cookie file ${authCookieFilepath} in unexpected format`);
+		}
+	}
+
+	return {
 		host: btcUri.hostname || process.env.BTCEXP_BITCOIND_HOST || "127.0.0.1",
 		port: btcUri.port || process.env.BTCEXP_BITCOIND_PORT || 8332,
-		username: btcAuth[0] || process.env.BTCEXP_BITCOIND_USER,
-		password: btcAuth[1] || process.env.BTCEXP_BITCOIND_PASS,
-		cookie: btcUri.query.cookie || process.env.BTCEXP_BITCOIND_COOKIE || path.join(os.homedir(), '.bitcoin', '.cookie'),
+
+		authType: authType,
+
+		username: username,
+		password: password,
+		
+		authCookieFilepath: authCookieFilepath,
+		
 		timeout: parseInt(btcUri.query.timeout || process.env.BTCEXP_BITCOIND_RPC_TIMEOUT || 5000),
-	},
+	};
+}
+
+module.exports = {
+	loadFreshRpcCredentials: loadFreshRpcCredentials,
+
+	rpc: loadFreshRpcCredentials(),
 
 	// optional: enter your api access key from ipstack.com below
 	// to include a map of the estimated locations of your node's