Simple UDP Growl packets in Lua

gistfile1.lua

require "luarocks.require"
require "pack"
require "socket"
require "md5"


Growl = {version = 1, registration = 0, notification = 1}

function Growl.new(hostname, appname)
  local mysock = assert(socket.udp())
  local hostip = assert(socket.dns.toip(hostname))
  return {host = hostip, port = 9887, sock = mysock, register = Growl.register, send = Growl.send, name = appname}
end

function Growl:register()
  local len = string.len(self.name)
  local data = string.pack(">AhAb", self.name, len, self.name, 0)
  local packet = {Growl.version, Growl.registration, len, 1, 1, data}
  local encpacket = string.pack(">bbhbbA", packet[1], packet[2], packet[3], packet[4], packet[5], packet[6])
  encpacket = encpacket .. md5.sum(encpacket)
  assert(self.sock:sendto(encpacket, self.host, self.port))
end

function Growl:send(title, message)
  local data = self.name .. title .. message .. self.name
  local packet = {Growl.version, Growl.notification, 0, string.len(self.name), string.len(title), string.len(message), string.len(self.name), data}
  local encpacket = string.pack(">bbhhhhhA", packet[1], packet[2], packet[3], packet[4], packet[5], packet[6], packet[7], packet[8])
  encpacket = encpacket .. md5.sum(encpacket)
  assert(self.sock:sendto(encpacket, self.host, self.port))
end

g = Growl.new("localhost", "Lua")
g:register()
g:send("Lua", "Lua sez hi!")