func (ts *testSrv) dnsHandler(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
m.Compress = false
// Normally this test DNS server will return 127.0.0.1 for everything.
// However, in some situations (for instance Docker), it's useful to return a
// different hardcoded host. You can do so by setting the FAKE_DNS environment
// variable.
fakeDNS := os.Getenv("FAKE_DNS")
if fakeDNS == "" {
fakeDNS = "127.0.0.1"
}
for _, q := range r.Question {
fmt.Printf("dns-srv: Query -- [%s] %s\n", q.Name, dns.TypeToString[q.Qtype])
switch q.Qtype {
case dns.TypeA:
record := new(dns.A)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0,
}
record.A = net.ParseIP(fakeDNS)
m.Answer = append(m.Answer, record)
case dns.TypeMX:
record := new(dns.MX)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeMX,
Class: dns.ClassINET,
Ttl: 0,
}
record.Mx = "mail." + q.Name
record.Preference = 10
m.Answer = append(m.Answer, record)
case dns.TypeTXT:
ts.mu.RLock()
value, present := ts.txtRecords[q.Name]
ts.mu.RUnlock()
if !present {
continue
}
record := new(dns.TXT)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeTXT,
Class: dns.ClassINET,
Ttl: 0,
}
record.Txt = []string{value}
m.Answer = append(m.Answer, record)
case dns.TypeCAA:
if q.Name == "bad-caa-reserved.com." || q.Name == "good-caa-reserved.com." {
record := new(dns.CAA)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeCAA,
Class: dns.ClassINET,
Ttl: 0,
}
record.Tag = "issue"
if q.Name == "bad-caa-reserved.com." {
record.Value = "sad-hacker-ca.invalid"
} else if q.Name == "good-caa-reserved.com." {
record.Value = "happy-hacker-ca.invalid"
}
m.Answer = append(m.Answer, record)
}
}
}
auth := new(dns.SOA)
auth.Hdr = dns.RR_Header{Name: "boulder.invalid.", Rrtype: dns.TypeSOA, Class: dns.ClassINET, Ttl: 0}
auth.Ns = "ns.boulder.invalid."
auth.Mbox = "master.boulder.invalid."
auth.Serial = 1
auth.Refresh = 1
auth.Retry = 1
auth.Expire = 1
auth.Minttl = 1
m.Ns = append(m.Ns, auth)
w.WriteMsg(m)
return
}