Add an option bindAddr which can be passed to TuyaLinkWizard (#15)

Co-authored-by: Mark <mark@mhack.io>

Author: bavis-m

index.js

@@ -25,7 +25,7 @@ const TuyaLink = require('./lib/link.js');
  *                                           password: 'example-password'});
  */
 class TuyaLinkWizard {
-  constructor({email, password, region = 'us', timezone = 'America/Chicago', apiKey, apiSecret, schema} = {}) {
+  constructor({email, password, region = 'us', timezone = 'America/Chicago', apiKey, apiSecret, schema, bindAddr} = {}) {
     if (!email || !password) {
       throw new Error('Both email and password must be provided');
     }
@@ -34,6 +34,7 @@ class TuyaLinkWizard {
     this.password = password;
     this.region = region;
     this.timezone = timezone;
+    this.bindAddr = bindAddr;
 
     this.api = new TuyaContext({
       baseUrl: `https://openapi.tuya${region}.com`,
@@ -123,7 +124,8 @@ class TuyaLinkWizard {
                                      token: token.token,
                                      secret: token.secret,
                                      ssid,
-                                     wifiPassword});
+                                     wifiPassword,
+                                     bindAddr: this.bindAddr});
 
       // While UDP packets are being sent, start polling for device
       debug('Polling cloud for details on token...');

lib/link.js

@@ -1,6 +1,7 @@
 const dgram = require('dgram');
 const delay = require('delay');
 const debug = require('debug')('@tuyapi/link:manual');
+const os = require('os');
 
 /**
  * A lower level option for linking
@@ -14,8 +15,10 @@ const debug = require('debug')('@tuyapi/link:manual');
 class TuyaLink {
   constructor() {
     this.abortBroadcasting = false;
+    this.bindAddr  = undefined;
   }
 
+
   /**
    * Thin wrapper for this.sendSmartLinkStart()
    * and this.sendSmartLinkData(). Unless you
@@ -66,6 +69,23 @@ class TuyaLink {
       throw new Error('Invalid WiFi password');
     }
 
+    if (options.bindAddr !== undefined)
+    {
+      if (typeof options.bindAddr !== 'string')
+      {
+        throw new Error('Invalid binding address');
+      }
+
+      const interfaces = os.networkInterfaces();
+      if (!Object.keys(interfaces).some(name =>
+            !interfaces[name].some(assigned => assigned.address.toLowerCase() === options.bindAddr.toLowerCase())
+      ))
+      {
+        throw new Error('Invalid binding address');
+      }
+      this.bindAddr = options.bindAddr;
+    }
+
     debug('Sending SmartLink initialization packets');
 
     await this.sendSmartLinkStart();
@@ -335,7 +355,7 @@ class TuyaLink {
       this.udpClient.on('listening', function () {
         this.setBroadcast(true);
       });
-      this.udpClient.bind(0);
+      this.udpClient.bind(0, this.bindAddr);
     }
 
     // 0-filled buffer