resolve_dns.go

package main

import "github.com/miekg/dns"

// ResolveIP resolves IP address using provided DNS server
func ResolveIP(url, server string) (string, error) {
  msg := new(dns.Msg)
  msg.Id = dns.Id()
  msg.RecursionDesired = true
  msg.Question = make([]dns.Question, 1)
  msg.Question[0] = dns.Question{url + ".", dns.TypeA, dns.ClassINET}
  in, err := dns.Exchange(msg, fmt.Sprintf("%s:53", server))
  if err != nil {
    return "", err
  }
  answers := strings.Split(in.Answer[0].String(), "\t")
  return answers[len(answers)-1], nil
}