Newbie udp socket question

[Prabhu Gurumurthy <pgurumur@...>]

Hello all,

I am a newbie to Lua and I was wondering whether somebody would give me
insight to the following:

1. I have trouble printing data returned from the UDP socket,
   When I print the data returned from the socket, it prints it in all
ascii, I know I have to do a  unpack like feature available in PERL or
struct feature in Python, I dont know what is the equivalent in Lua. Can
somebody point give me a cluestick?

2. Is there a getopt like feature that I can use in lua.

program (intention is to print ntp time from a server, in other words,
sntp client, without modifications):

#!/usr/bin/env lua
-- $Id: sntp.lua,v 1.1 2007/05/15 03:33:01 pgurumur Exp pgurumur $

ntp = {}

function ntp:Create(Server, Port)
   local socket = require "socket"
   local err = false
   sockTable = {}

   if Server then
      sockTable._server = Server
   end

   if Port then
      sockTable._port = Port
   end

   if not (sockTable._server and sockTable._port) then
      error("need server and port defined")
   end

   assert(socket.dns.toip(sockTable._server))
   sockTable._udpSocket = socket.udp()
   sockTable._udpSocket:setpeername(sockTable._server, sockTable._port)
   sockTable._udpSocket:settimeout(3)
end

function ntp:Send(Data)
   local sent = 0
   if Data then
      sent, err = sockTable._udpSocket:send(Data)
      if err then
         error("send " ..err)
      end
   end

   return sent
end

function ntp:Receive()
   local datagram, err = sockTable._udpSocket:receive()
   if not datagram then
      error("receive: " ..err)
   end

   return datagram
end

function GetInitData()
   data = string.format("%x", 0x23) .. string.rep("'\0'", 47)
   return data
end

port = 123

if arg[2] then
   port = arg[2]
end

if arg[1] then
   local host = arg[1]
   ntp:Create(host, port)
   ntp:Send(GetInitData())
   RetData = ntp:Receive()
   Data = string.format("%s", RetData)
   print(Data)
else
   print(arg[0] .. " hostname")
end


Thanks a lot in advance for your help
Prabhu
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