add AXFR request handling to support slaves

pkg/nameserver/handler.go

@@ -2,12 +2,48 @@ package nameserver
 
 import (
 	"fmt"
+	"net"
 	"strings"
 
 	"github.com/miekg/dns"
 )
 
 func (n *Nameserver) handleRequest(w dns.ResponseWriter, r *dns.Msg) {
+
+	if len(r.Question) == 1 {
+		q := r.Question[0]
+		if q.Qtype == dns.TypeAXFR || q.Qtype == dns.TypeIXFR { // Get remote IP
+			remoteIP, _, err := net.SplitHostPort(w.RemoteAddr().String())
+			if err != nil {
+				n.Logger.Errorw("Failed to parse remote address", "err", err)
+				m := new(dns.Msg)
+				m.SetReply(r)
+				m.Rcode = dns.RcodeRefused
+				_ = w.WriteMsg(m)
+				return
+			}
+
+			// Check if remote IP is in slave list
+			allowed := false
+			for _, slave := range n.Config.General.SlaveHosts {
+				if remoteIP == slave {
+					allowed = true
+					break
+				}
+			}
+
+			if !allowed {
+				n.Logger.Warnw("AXFR/IXFR request denied", "remote", remoteIP)
+				m := new(dns.Msg)
+				m.SetReply(r)
+				m.Rcode = dns.RcodeRefused
+				_ = w.WriteMsg(m)
+				return
+			}
+			n.handleAXFR(w, r)
+			return
+		}
+	}
 	m := new(dns.Msg)
 	m.SetReply(r)
 	// handle edns0
@@ -161,3 +197,77 @@ func (n *Nameserver) getRecord(name string, qtype uint16) ([]dns.RR, error) {
 	}
 	return rr, nil
 }
+
+func (n *Nameserver) handleAXFR(w dns.ResponseWriter, r *dns.Msg) {
+
+	if len(r.Question) == 0 {
+		return
+	}
+
+	zone := dns.Fqdn(r.Question[0].Name)
+
+	records, ok := n.Domains[zone]
+	if !ok {
+		m := new(dns.Msg)
+		m.SetRcode(r, dns.RcodeNameError)
+		_ = w.WriteMsg(m)
+		return
+	}
+
+	// AXFR muss über Transfer laufen
+	tr := new(dns.Transfer)
+
+	c := make(chan *dns.Envelope)
+
+	go func() {
+		defer close(c)
+
+		var rr []dns.RR
+
+		// Start SOA
+		rr = append(rr, n.SOA)
+
+		// NS
+		rr = append(rr, records.NS...)
+
+		// Andere Records
+		// rr = append(rr, filterSOA(records.Records)...)
+		rr = append(rr, records.Records...)
+
+		// TXT Records nur für diese Zone!
+		txtRecords, err := n.DB.GetTXTForAllDomains()
+		if err == nil {
+			for _, rec := range txtRecords {
+				if rec.Value == "" {
+					continue
+				}
+
+				fqdn := dns.Fqdn(rec.Subdomain + "." + zone)
+
+				txtRR := &dns.TXT{
+					Hdr: dns.RR_Header{
+						Name:   fqdn,
+						Rrtype: dns.TypeTXT,
+						Class:  dns.ClassINET,
+						Ttl:    1,
+					},
+					Txt: []string{rec.Value},
+				}
+
+				rr = append(rr, txtRR)
+
+				n.Logger.Debugw("handleAXFR TXT Record", "subdomain", rec.Subdomain, "value", rec.Value, "fqdn", fqdn)
+				rr = append(rr, txtRR)
+			}
+		} else {
+			n.Logger.Errorw("Failed to get TXT records for AXFR", "error", err)
+		}
+
+		// End SOA
+		rr = append(rr, n.SOA)
+
+		c <- &dns.Envelope{RR: rr}
+	}()
+
+	_ = tr.Out(w, r, c)
+}