Feature/ws api (#72)

initial changes to support websockets as an alternative to webhooks

lib/utils/base-requestor.js

@@ -0,0 +1,75 @@
+const assert = require('assert');
+const Emitter = require('events');
+const crypto = require('crypto');
+const timeSeries = require('@jambonz/time-series');
+let alerter ;
+
+class BaseRequestor extends Emitter {
+  constructor(logger, account_sid, hook, secret) {
+    super();
+    assert(typeof hook === 'object');
+
+    this.logger = logger;
+    this.url = hook.url;
+
+    this.username = hook.username;
+    this.password = hook.password;
+    this.secret = secret;
+    this.account_sid = account_sid;
+
+    const {stats} = require('../../').srf.locals;
+    this.stats = stats;
+
+    if (!alerter) {
+      alerter = timeSeries(logger, {
+        host: process.env.JAMBONES_TIME_SERIES_HOST,
+        commitSize: 50,
+        commitInterval: 'test' === process.env.NODE_ENV ? 7 : 20
+      });
+    }
+  }
+
+  get Alerter() {
+    return alerter;
+  }
+
+  close() {
+    /* subclass responsibility */
+  }
+
+  _computeSignature(payload, timestamp, secret) {
+    assert(secret);
+    const data = `${timestamp}.${JSON.stringify(payload)}`;
+    return crypto
+      .createHmac('sha256', secret)
+      .update(data, 'utf8')
+      .digest('hex');
+  }
+
+  _generateSigHeader(payload, secret) {
+    const timestamp = Math.floor(Date.now() / 1000);
+    const signature = this._computeSignature(payload, timestamp, secret);
+    const scheme = 'v1';
+    return {
+      'Jambonz-Signature': `t=${timestamp},${scheme}=${signature}`
+    };
+  }
+
+  _isAbsoluteUrl(u) {
+    return typeof u === 'string' &&
+      u.startsWith('https://') || u.startsWith('http://') ||
+      u.startsWith('ws://') || u.startsWith('wss://');
+  }
+  _isRelativeUrl(u) {
+    return typeof u === 'string' && u.startsWith('/');
+  }
+  _roundTrip(startAt) {
+    const diff = process.hrtime(startAt);
+    const time = diff[0] * 1e3 + diff[1] * 1e-6;
+    return time.toFixed(0);
+  }
+
+
+}
+
+module.exports = BaseRequestor;