plugin/transfer: collect all notify errors instead of shadowing (#8283)

* plugin/transfer: collect all notify errors instead of shadowing

Signed-off-by: ncesam <rybushkin09@bk.ru>

* plugin/transfer: add regression test for notify multiple failures

Signed-off-by: ncesam <rybushkin09@bk.ru>

---------

Signed-off-by: ncesam <rybushkin09@bk.ru>

plugin/transfer/notify.go

@@ -1,6 +1,7 @@
 package transfer
 
 import (
+	"errors"
 	"fmt"
 	"net"
 
@@ -25,17 +26,17 @@ func (t *Transfer) Notify(zone string) error {
 	}
 	c := notifyClient(x)
 
-	var err1 error
+	var errs error
 	for _, t := range x.to {
 		if t == "*" {
 			continue
 		}
 		if err := sendNotify(c, m, t); err != nil {
-			err1 = err
+			errs = errors.Join(errs, err)
 		}
 	}
 	log.Debugf("Sent notifies for zone %q to %v", zone, x.to)
-	return err1 // this only captures the last error
+	return errs
 }
 
 func notifyClient(x *xfr) *dns.Client {

plugin/transfer/notify_test.go

@@ -2,7 +2,10 @@ package transfer
 
 import (
 	"net"
+	"strings"
 	"testing"
+
+	"github.com/miekg/dns"
 )
 
 func TestNotifyClientSource(t *testing.T) {
@@ -25,3 +28,61 @@ func TestNotifyClientSource(t *testing.T) {
 		t.Fatalf("expected source address %s, got %s", source, addr.IP)
 	}
 }
+
+func TestNotifyMultipleFailures(t *testing.T) {
+	// Start two local UDP listeners returning different rcodes
+	l1, err := net.ListenPacket("udp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("failed to listen: %v", err)
+	}
+	defer l1.Close()
+
+	l2, err := net.ListenPacket("udp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("failed to listen: %v", err)
+	}
+	defer l2.Close()
+
+	serve := func(conn net.PacketConn, rcode int) {
+		buf := make([]byte, 512)
+		for {
+			n, addr, err := conn.ReadFrom(buf)
+			if err != nil {
+				return
+			}
+			msg := new(dns.Msg)
+			if err := msg.Unpack(buf[:n]); err != nil {
+				continue
+			}
+			msg.SetReply(msg)
+			msg.Rcode = rcode
+			out, _ := msg.Pack()
+			conn.WriteTo(out, addr)
+		}
+	}
+
+	go serve(l1, dns.RcodeServerFailure)
+	go serve(l2, dns.RcodeRefused)
+
+	tr := &Transfer{
+		xfrs: []*xfr{
+			{
+				Zones: []string{"example.com."},
+				to:    []string{l1.LocalAddr().String(), l2.LocalAddr().String()},
+			},
+		},
+	}
+
+	err = tr.Notify("example.com.")
+	if err == nil {
+		t.Fatal("expected error from Notify, got nil")
+	}
+
+	errStr := err.Error()
+	if !strings.Contains(errStr, l1.LocalAddr().String()) || !strings.Contains(errStr, "SERVFAIL") {
+		t.Errorf("expected error to contain %q and SERVFAIL, got: %v", l1.LocalAddr().String(), errStr)
+	}
+	if !strings.Contains(errStr, l2.LocalAddr().String()) || !strings.Contains(errStr, "REFUSED") {
+		t.Errorf("expected error to contain %q and REFUSED, got: %v", l2.LocalAddr().String(), errStr)
+	}
+}