firewalla-arp-dump.js

#!/usr/bin/env node

const spawn = require('child_process').spawn;
const https = require("https");

const arp = spawn("arp", ["-n"]);
const arpArray = [];
let buffer = '';
let errstream = '';
arp.stdout.on('data', function (data) {
    buffer += data;
});
arp.stderr.on('data', function (data) {
    errstream += data;
});

arp.on('close', async function (code) {
    if (code !== 0) {
        console.log("Error running arp " + code + " " + errstream);
        cb(true, code);
        return;
    }

    const table = buffer.split('\n');

    for (var line=1; line <= table.length - 1; line++) {
        const entry = table[line].split(/[ ]+/);
        console.log(entry);

        if (entry[3] === 'C') {
          arpArray.push(
            {
              ip: entry[0],
              mac: entry[2],
            }
          );
        }
    }
    console.log(arpArray);
    sendARPData(arpArray);
});


function sendARPData(data) {
  const dataString = JSON.stringify(data);

  const options = {
    hostname: 'homeserver',
    port: '443',
    path: '/api/webhook/firewalla',
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Content-Length': dataString.length,
    },
    timeout: 1000,
  }

  try {
    const req = https.request(options, (res) => {
      if (res.statusCode < 200 || res.statusCode > 299) {
        return (new Error(`HTTP status code ${res.statusCode}`))
      }

      const body = [];
      res.on('data', (chunk) => body.push(chunk));
      res.on('end', () => {
        const resString = Buffer.concat(body).toString();
        console.log(resString);
      })
    });

    req.on('error', (err) => {
      console.error(err)
    });

    req.on('timeout', () => {
      req.destroy()
      return(new Error('Request time out'))
    });

    req.write(dataString);
    req.end();

  } catch (e) {
    console.log("ERROR", e);
  }

}