Revert "Implement notifies for transfer plugin (#3972)" (#3995)

This reverts commit 68f1dd5ddf.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

plugin/auto/auto.go

@@ -10,7 +10,6 @@ import (
 	"github.com/coredns/coredns/plugin/file"
 	"github.com/coredns/coredns/plugin/metrics"
 	"github.com/coredns/coredns/plugin/pkg/upstream"
-	"github.com/coredns/coredns/plugin/transfer"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -22,8 +21,7 @@ type (
 		Next plugin.Handler
 		*Zones
 
-		metrics  *metrics.Metrics
-		transfer *transfer.Transfer
+		metrics *metrics.Metrics
 		loader
 	}
 
@@ -32,6 +30,8 @@ type (
 		template  string
 		re        *regexp.Regexp
 
+		// In the future this should be something like ZoneMeta that contains all this stuff.
+		transferTo     []string
 		ReloadInterval time.Duration
 		upstream       *upstream.Upstream // Upstream for looking up names during the resolution process.
 	}
@@ -59,6 +59,11 @@ func (a Auto) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 		return dns.RcodeServerFailure, nil
 	}
 
+	if state.QType() == dns.TypeAXFR || state.QType() == dns.TypeIXFR {
+		xfr := file.Xfr{Zone: z}
+		return xfr.ServeDNS(ctx, w, r)
+	}
+
 	answer, ns, extra, result := z.Lookup(ctx, state, qname)
 
 	m := new(dns.Msg)