decode extended responseName by context class

v3/extended.go

@@ -89,6 +89,14 @@ func (l *Conn) Extended(er *ExtendedRequest) (*ExtendedResponse, error) {
 	}
 
 	for _, child := range extResp.Children {
+		// responseName [10] and responseValue [11] are context-class and
+		// optional. The preceding resultCode is a universal ENUMERATED whose
+		// tag number (10) is the same as responseName, so a child must be
+		// matched on its class as well, otherwise the resultCode is read as
+		// the responseName whenever the server omits the latter.
+		if child.ClassType != ber.ClassContext {
+			continue
+		}
 		switch child.Tag {
 		case ber.TagEnumerated:
 			response.Name = child.Data.String()

v3/extended_test.go

@@ -3,6 +3,7 @@
 import (
 	"testing"
 
+	ber "github.com/go-asn1-ber/asn1-ber"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -35,6 +36,42 @@
 	t.Logf("%#v\n", rfc4532resp)
 }
 
+// TestExtendedResponseNameOmitted feeds a successful ExtendedResponse that
+// carries a responseValue but no responseName. The resultCode is a universal
+// ENUMERATED whose tag number matches responseName [10]; decoding must not
+// report the result code as the name.
+func TestExtendedResponseNameOmitted(t *testing.T) {
+	ptc := newPacketTranslatorConn()
+	defer ptc.Close()
+
+	conn := NewConn(ptc, false)
+	conn.Start()
+	defer conn.Close()
+
+	go func() {
+		req, err := ptc.ReceiveRequest()
+		if err != nil {
+			return
+		}
+		msgID := req.Children[0].Value.(int64)
+
+		resp := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "LDAP Response")
+		resp.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, msgID, "MessageID"))
+		extResp := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationExtendedResponse, nil, "Extended Response")
+		extResp.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagEnumerated, 0, "resultCode"))
+		extResp.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "matchedDN"))
+		extResp.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "diagnosticMessage"))
+		extResp.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, ber.TagEmbeddedPDV, "payload", "responseValue"))
+		resp.AppendChild(extResp)
+		_ = ptc.SendResponse(resp)
+	}()
+
+	result, err := conn.Extended(NewExtendedRequest("1.2.3.4", nil))
+	assert.NoError(t, err)
+	assert.Equal(t, "", result.Name)
+	assert.NotNil(t, result.Value)
+}
+
 func TestExtendedRequest_FastBind(t *testing.T) {
 	conn, err := DialURL(ldapServer)
 	if err != nil {