#!/usr/bin/env ruby
require 'net/http'
FAKEDNS_URL="http://my_server:4567/"
INTERFACE="eth0"
IFCONFIG_CMD="/sbin/ifconfig"
HOSTNAME_CMD="hostname"

hostname = `#{HOSTNAME_CMD}`.strip
ifinfo = `#{IFCONFIG_CMD} #{INTERFACE}`
if ifinfo !~ /HWaddr\s+([0-9A-Za-z:]+)/
  raise "no mac address in ifinfo:\n" + ifinfo
end
mac = $1
if ifinfo !~ /inet\s+addr:([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)/
  raise "no ip address in ifinfo:\n" + ifinfo
end
ip = $1

puts "FakeDNS: posting host '#{hostname}' ip '#{ip}' at mac '#{mac}' to server at #{FAKEDNS_URL}"
res = Net::HTTP.post_form(URI.parse(FAKEDNS_URL),
  {'mac' => mac, 'name' => hostname, 'ip' => ip})
case res
when Net::HTTPSuccess
  puts "Posted OK."
else
  puts "Posting IP address failed:"
  puts res.body
end