1 files changed, 24 insertions, 97 deletions

diff --git a/plugin/file/xfr.go b/plugin/file/xfr.go
index f7192165b..28c3a3a9d 100644
--- a/plugin/file/xfr.go
+++ b/plugin/file/xfr.go
@@ -1,118 +1,45 @@
 package file
 
 import (
-	"context"
-	"fmt"
-	"sync"
-
-	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/file/tree"
-	"github.com/coredns/coredns/request"
+	"github.com/coredns/coredns/plugin/transfer"
 
 	"github.com/miekg/dns"
 )
 
-// Xfr serves up an AXFR.
-type Xfr struct {
-	*Zone
-}
-
-// ServeDNS implements the plugin.Handler interface.
-func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
-	state := request.Request{W: w, Req: r}
-	if !x.TransferAllowed(state) {
-		return dns.RcodeServerFailure, nil
-	}
-	if state.QType() != dns.TypeAXFR && state.QType() != dns.TypeIXFR {
-		return 0, plugin.Error(x.Name(), fmt.Errorf("xfr called with non transfer type: %d", state.QType()))
-	}
-
-	// For IXFR we take the SOA in the IXFR message (if there), compare it what we have and then decide to do an
-	// AXFR or just reply with one SOA message back.
-	if state.QType() == dns.TypeIXFR {
-		code, _ := x.ServeIxfr(ctx, w, r)
-		if plugin.ClientWrite(code) {
-			return code, nil
-		}
+// Transfer implements the transfer.Transfer interface.
+func (f File) Transfer(zone string, serial uint32) (<-chan []dns.RR, error) {
+	z, ok := f.Zones.Z[zone]
+	if !ok || z == nil {
+		return nil, transfer.ErrNotAuthoritative
 	}
+	return z.Transfer(serial)
+}
 
+// Transfer transfers a zone with serial in the returned channel and implements IXFR fallback, by just
+// sending a single SOA record.
+func (z *Zone) Transfer(serial uint32) (<-chan []dns.RR, error) {
 	// get soa and apex
-	apex, err := x.ApexIfDefined()
+	apex, err := z.ApexIfDefined()
 	if err != nil {
-		return dns.RcodeServerFailure, nil
+		return nil, err
 	}
 
-	ch := make(chan *dns.Envelope)
-	tr := new(dns.Transfer)
-	wg := new(sync.WaitGroup)
-	wg.Add(1)
+	ch := make(chan []dns.RR)
 	go func() {
-		tr.Out(w, r, ch)
-		wg.Done()
-	}()
+		if serial != 0 && apex[0].(*dns.SOA).Serial == serial { // ixfr fallback, only send SOA
+			ch <- []dns.RR{apex[0]}
 
-	rrs := []dns.RR{}
-	l := len(apex)
-
-	ch <- &dns.Envelope{RR: apex}
-
-	x.Walk(func(e *tree.Elem, _ map[uint16][]dns.RR) error {
-		rrs = append(rrs, e.All()...)
-		if len(rrs) > 500 {
-			ch <- &dns.Envelope{RR: rrs}
-			l += len(rrs)
-			rrs = []dns.RR{}
+			close(ch)
+			return
 		}
-		return nil
-	})
 
-	if len(rrs) > 0 {
-		ch <- &dns.Envelope{RR: rrs}
-		l += len(rrs)
-		rrs = []dns.RR{}
-	}
+		ch <- apex
+		z.Walk(func(e *tree.Elem, _ map[uint16][]dns.RR) error { ch <- e.All(); return nil })
+		ch <- []dns.RR{apex[0]}
 
-	ch <- &dns.Envelope{RR: []dns.RR{apex[0]}} // closing SOA.
-	l++
-
-	close(ch) // Even though we close the channel here, we still have
-	wg.Wait() // to wait before we can return and close the connection.
-
-	log.Infof("Outgoing transfer of %d records of zone %s to %s done with %d SOA serial", l, x.origin, state.IP(), apex[0].(*dns.SOA).Serial)
-	return dns.RcodeSuccess, nil
-}
-
-// Name implements the plugin.Handler interface.
-func (x Xfr) Name() string { return "xfr" }
-
-// ServeIxfr checks if we need to serve a simpler IXFR for the incoming message.
-// See RFC 1995 Section 3: "... and the authority section containing the SOA record of client's version of the zone."
-// and Section 2, paragraph 4 where we only need to echo the SOA record back.
-// This function must be called when the qtype is IXFR. It returns a plugin.ClientWrite(code) == false, when it didn't
-// write anything and we should perform an AXFR.
-func (x Xfr) ServeIxfr(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
-	if len(r.Ns) != 1 {
-		return dns.RcodeServerFailure, nil
-	}
-	soa, ok := r.Ns[0].(*dns.SOA)
-	if !ok {
-		return dns.RcodeServerFailure, nil
-	}
-
-	x.RLock()
-	if x.Apex.SOA == nil {
-		x.RUnlock()
-		return dns.RcodeServerFailure, nil
-	}
-	serial := x.Apex.SOA.Serial
-	x.RUnlock()
+		close(ch)
+	}()
 
-	if soa.Serial == serial { // Section 2, para 4; echo SOA back. We have the same zone
-		m := new(dns.Msg)
-		m.SetReply(r)
-		m.Answer = []dns.RR{soa}
-		w.WriteMsg(m)
-		return 0, nil
-	}
-	return dns.RcodeServerFailure, nil
+	return ch, nil
 }