automatically scan for and join open internet enabled wifi networks on linux using node.js (tested on raspberry pi raspbian)

readme.md

note: I converted this script into the much easier to install joinopenwifi module on NPM

see https://github.com/maxogden/joinopenwifi#joinopenwifi for installation instructions

wifiscanner.js

#!/usr/bin/env node
var iw = require('iwlist')(process.argv[2] || 'wlan0')
var tried = {}
var silent = process.argv[4]

// wait for some time so that linux can try to associate with a known network first
var delay = process.argv[3] || 30000
if (!silent) console.log('waiting ' + delay/1000 + ' seconds')
setTimeout(start, process.argv[3] || 30000)

function start() {
  iw.associated(function(err, associated) {
    if (associated) {
      if (!silent) console.log('already associated -- exiting')
      return process.exit()
    }
    findOpenNetwork()
  })
}

function findOpenNetwork() {
  if (!silent) console.log('scanning for open networks...')
  iw.scan(function(err, networks) {
    if (err) {
      if (!silent) console.log('error scanning', err)
      return process.exit()
    }
    networks = removeSecureNetworks(networks)
    if (networks.length === 0) {
      if (!silent) console.log('no open networks nearby')
      return process.exit()
    }
    var network = getNextNetwork(networks)
    if (!silent) console.log('attempting to join ' + network.essid)
    connectToNetwork(network.essid)
  })
}

function connectToNetwork(essid) {
  iw.connect(essid, function(err) {
    if (err) {
      if (!silent) console.log('error joining ' + essid, err)
      return start()
    }
    iw.online(function(err) {
      if (err) {
        if (!silent) console.log(essid + ' is not internet enabled', err)
        return findOpenNetwork()
      }
      if (!silent) console.log('got online successfully via network: ' + essid)
      process.exit()
    })
  })
}

function removeSecureNetworks(networks) {
  openNetworks = []
  networks.map(function(network) {
    if (!network.encrypted) openNetworks.push(network)
  })
  return openNetworks
}

function getNextNetwork(networks) {
  var network = networks.shift()
  if (!network) return process.exit()
  while (tried[network.essid]) {
    network = networks.shift()
  }
  return network
}