ratchet-example.lua

-- Example of using Ratchet to resolve DNS queries
-- Inspect function to print the results:
function inspect(prefix, t)
  for k,v in pairs(t) do
    if (type(v) == "table") then
      inspect(string.format("%s (%s):", prefix, k), v)
    else
      print(prefix, string.format("%s: %s", k, v))
    end
  end
end

-- Here are the questions to test.
-- NOTE: currently querying a TXT on dnsimple.com core dumps (dig dnsimple.com txt)
questions = {}
questions["dnsimple.com"] = {
  [1] = "a",
  [2] = "ns",
  [3] = "mx",
  [4] = "spf", -- There should be a result here but none is reported (dig dnsimple.com spf) 
  [5] = "srv" -- There should be a result here but none is reported (dig dnsimple.com srv)
  -- [6] = "sshfp" -- This should work, but enabling it causes processing to stop when it is processed
  -- [7=] = "txt" -- SEGFAULT
}
questions["www.dnsimple.com"] = {
  [1] = "cname"
}
questions["ns1.dnsimple.com"] = {
  [1] = "aaaa"
}
questions["naptr-test.dnsimple.com"] = {
  [1] = "naptr" -- Not supported (dig naptr-test.dnsimple.com naptr)
}

-- The ratchet code. Switch out the name and type as needed.
require "ratchet"
kernel = ratchet.new(function()
  for qname, qtypes in pairs(questions) do
    for i, qtype in ipairs(qtypes) do
      local rec, err
      local status, ex = pcall(function()
        rec, err = ratchet.dns.query(qname, qtype)
      end) 
      if status then
        if (type(err) == "nil") then
          if (type(rec) == "nil") then
            print(string.format("No records for %s (%s)", qname, qtype))
          else
            inspect(string.format("%s (%s)", qname, qtype), rec)
          end
        else
          print(string.format("Error for %s (%s): %s", qname, qtype, err))
        end
      else
        print(string.format("Exception for %s (%s): %s", qname, qtype, ex))
      end
    end
  end
end)
kernel:loop()