func answerCNAME(q *dns.Question, v *DNSValue) (dns.RR, string) {
// Info: http://en.wikipedia.org/wiki/CNAME_record
answer := new(dns.CNAME)
answer.Header().Name = q.Name
answer.Header().Rrtype = dns.TypeCNAME
answer.Header().Class = dns.ClassINET
answer.Target = strings.TrimSuffix(v.Value, ".") + "."
return answer, answer.Target
}
func (c *config) flattenCNAME(in *dns.CNAME) ([]dns.RR, error) { // TODO: cache CNAME lookups
h := in.Header()
answers := []dns.RR{}
m := new(dns.Msg)
m.SetQuestion(in.Target, dns.TypeA)
m.RecursionDesired = true
d := new(dns.Client)
record, _, err := d.Exchange(m, c.resolver) // TODO: try multiple resolvers
if err != nil {
return nil, err
}
if record == nil || record.Rcode == dns.RcodeNameError || record.Rcode != dns.RcodeSuccess {
return nil, fmt.Errorf("Record error code %s: %s", record.Rcode, err.Error())
}
for _, a := range record.Answer {
if r, ok := a.(*dns.A); ok {
out := new(dns.A)
out.Hdr = dns.RR_Header{Name: h.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 300}
out.A = r.A
answers = append(answers, out)
}
}
return answers, nil
}