Example #1
0
func handleDnsRequest(w dns.ResponseWriter, req *dns.Msg) {
	r := new(dns.Msg)
	r.SetReply(req)
	r.Authoritative = true

	if len(req.Question) > 1 || req.Rcode != dns.OpcodeQuery {
		r.SetRcode(req, dns.RcodeNotImplemented)
	}

	if len(req.Question) == 0 {
		r.SetRcode(req, dns.RcodeFormatError)
	}

	if r.Rcode != dns.RcodeSuccess {
		w.WriteMsg(r)
		dnsReportChan <- 1
		return
	}

	q := req.Question[0]
	log.Debug("dns server: question=%v type=%v remote_host=%v", q.Name, q.Qtype, w.RemoteAddr())

	switch q.Qtype {
	case dns.TypeA:
		h, _ := randomHost()
		if h == "" || !isIPv4(h) {
			if *f_randomhosts {
				h = randomIPv4Addr()
			} else {
				// return NXDOMAIN
				r.SetRcode(req, dns.RcodeNameError)
				break
			}
		}

		resp := new(dns.A)
		resp.Hdr = dns.RR_Header{
			Name:   q.Name,
			Rrtype: dns.TypeA,
			Class:  dns.ClassINET,
			Ttl:    ttl,
		}
		resp.A = net.ParseIP(h)
		r.Answer = append(r.Answer, resp)
	case dns.TypeAAAA:
		h, _ := randomHost()
		if h == "" || !isIPv6(h) {
			if *f_randomhosts {
				h = randomIPv6Addr()
			} else {
				// return NXDOMAIN
				r.SetRcode(req, dns.RcodeNameError)
				break
			}
		}

		resp := new(dns.AAAA)
		resp.Hdr = dns.RR_Header{
			Name:   q.Name,
			Rrtype: dns.TypeAAAA,
			Class:  dns.ClassINET,
			Ttl:    ttl,
		}
		resp.AAAA = net.ParseIP(h)
		r.Answer = append(r.Answer, resp)
	case dns.TypeCNAME:
		resp := new(dns.CNAME)
		resp.Hdr = dns.RR_Header{
			Name:   q.Name,
			Rrtype: dns.TypeCNAME,
			Class:  dns.ClassINET,
			Ttl:    ttl,
		}
		resp.Target = fmt.Sprintf("cname.%s", q.Name)
		r.Answer = append(r.Answer, resp)
	case dns.TypeMX:
		resp := new(dns.MX)
		resp.Hdr = dns.RR_Header{
			Name:   q.Name,
			Rrtype: dns.TypeMX,
			Class:  dns.ClassINET,
			Ttl:    ttl,
		}
		resp.Mx = fmt.Sprintf("mx.%s", q.Name)
		r.Answer = append(r.Answer, resp)
	case dns.TypeSOA:
		resp := new(dns.SOA)
		resp.Hdr = dns.RR_Header{
			Name:   q.Name,
			Rrtype: dns.TypeSOA,
			Class:  dns.ClassINET,
			Ttl:    ttl,
		}
		resp.Ns = fmt.Sprintf("ns.%s", q.Name)
		resp.Mbox = fmt.Sprintf("admin-%s", q.Name)
		r.Answer = append(r.Answer, resp)
	}
	w.WriteMsg(r)
	dnsReportChan <- 1
}