package main

import (
	"errors"
	"fmt"
	"net"
	"time"

	"github.com/miekg/dns"
)


type DnsTest struct {
  server net.IP
  testHost string
  rtt time.Duration
  answer net.IP 
}

func RunTest(srv net.IP, host string) (*DnsTest, error) {
  m := new(dns.Msg)
  m.SetQuestion(host, dns.TypeA)
  c := new(dns.Client)
  in, rtt, err := c.Exchange(m, fmt.Sprintf("%s:53", srv))
  if err != nil {
    return nil, err
  }
  for _, answer := range in.Answer {
    if t, ok := answer.(*dns.A); ok {
      return &DnsTest{server: srv, testHost: host, rtt: rtt, answer: t.A}, nil
    }
  }
  return nil, errors.New("No answer found")
}


func main() {
  testHosts := []string{ "gitea.snamellit.com", "www.snamellit.com", "home.snamellit.com", "nas.snamellit.com" , "gitlab.melexis.com", "dsl.melexis.com", "cvs.tess.elex.be", "cvs.sofia.elex.be", "cvs.sensors.elex.be", "cvs.erfurt.elex.be", "www.google.com" }
  for _, host := range testHosts {
    t, err := RunTest(net.ParseIP("192.168.1.1"), host + ".")
      if err != nil {
      fmt.Println("Error for ", host, ":",  err.Error())
        continue
      }
      fmt.Println("Answer ", t.server, t.testHost, t.answer, t.rtt)
  }
}