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hortinstein / node-dash-button

A small module to emit events when an Amazon Dash Button is pressed
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node-dash-button

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Place it. Hack it. Press it. Get it.

This module was inspired by this fantastic article by Edward Bensen.

It is a simple library that will allow you to utilize a dash button to emit an event. I am using the same strategy of watching for dash generated ARP requests as the article above.

Contents

Installation Instructions

The following should work for ubuntu, the main thing for any os is getting the libpcap dependancy.

# dependancy on libpcap for reading packets
$ sudo apt-get install libpcap-dev
$ npm install node-dash-button

First Time Dash Setup

Follow Amazon's instructions to configure your button to send messages when you push them but not actually order anything. When you get a Dash button, Amazon gives you a list of setup instructions to get going. Just follow this list of instructions, but don’t complete the final step (#3 I think) Do not select a product, just exit the app.

Find a Dash

To find a dash on your network, run the following from the node-dash-button directory in node_modules:

# you may need to use sudo due to libpcap running in permiscuous mode
$ cd node_modules/node-dash-button
$ node bin/findbutton

It will watch for new arp and udp requests on your network. There may be several such requests, so press it a few times to make sure. Copy the hardware address as shown below, and make a note of the protocol used.

hw address

Note: If your computer has multiple active network interfaces, findbutton will use the first one listed. If you need to overwrite this setting, pass your preferred interface as the first argument, such as node bin/findbutton eth6.

Usage docs:

var dash_button = require('node-dash-button');
var dash = dash_button(mac_addresses, iface, timeout, protocol);

Example Usage:

For a single dash

//warning this may trigger multiple times for one press
//...usually triggers twice based on testing for each press
var dash_button = require('node-dash-button');
var dash = dash_button("8f:3f:20:33:54:44", null, null, 'all'); //address from step above
dash.on("detected", function (){
    console.log("omg found");
});

For multiple dashes:

var dash_button = require('node-dash-button');
var dash = dash_button(["8f:3f:20:33:54:44","2e:3f:20:33:54:22"], null, null, 'all'); //address from step above
dash.on("detected", function (dash_id){
    if (dash_id === "8f:3f:20:33:54:44"){
        console.log("omg found");
    } else if (dash_id === "2e:3f:20:33:54:22"){
        console.log("found the other!");
    }
});

Binding To Specific Interface: By default, the dash button is bound to the first device with an address. To bind the button to a specific interface, such as eth6, pass the name of the interface as the 2nd argument to the invocation method.

var dash_button = require('node-dash-button');
var dash = dash_button("8f:3f:20:33:54:44", "eth6"); //address from step above
dash.on("detected", function (){
  console.log("omg found - on eth6!");
});

Adjusting the Timeout (if multiple presses are detected): By default the timeout between presses is 5 seconds. Depending on the network this may not be enough. Use the following syntax to specify a new timeout in miliseconds:

var dash_button = require('node-dash-button');
var dash = dash_button("8f:3f:20:33:54:44", null, 60000); //address from step above
dash.on("detected", function (){
  console.log("omg found - on eth6!");
});

ARP, UDP or both: By default the protocol monitored is ARP, which is what the earlier buttons tend to use. Newer buttons however, are using UDP to make thier request. By setting protocol to 'arp', 'udp', or 'all' (both), you can optimise the script to your setup.

Note: If your button was initially picked up using ARP, but is now not being picked up, it's possible that the button has switched to UDP.

var dash_button = require('node-dash-button');
var dash = dash_button("8f:3f:20:33:54:44", null, null, "all"); //address from step above
dash.on("detected", function (){
  console.log("omg found");
});

Running Tests:

Due to the use of pcap permiscuous monitoring this was difficult to test in CI environments, so I ended up making two testing suites. One uses the live pcap library and does actual packet capturing/arp injections. The other uses mockery to fake pcap packets. I will have an upcoming blog post on how I did this, because it was interesting.

To run a live test of the code (requiring root due to permiscuous access please run).

sudo npm run-script livetest

This will actually inject ARP packets to the network to run the tests to ensure detection.

I wanted to use various CI tools that would not allow the pcap functions to work, so I ended up mocking their functions. To run the mock tests use:

npm test

Example Projects:

I collected a few examples I found on github of how people are using this module, some projects are more mature than others

To do

Contributions

Accepting pull requests!

License

The MIT License (MIT)

Copyright (c) 2016 Alex Hortin

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.