From ce4498339d158a9f2f78a91f64d5442d4dcca12e Mon Sep 17 00:00:00 2001
From: Doug Fawley <dfawley@google.com>
Date: Mon, 1 Mar 2021 15:08:47 -0800
Subject: [PATCH] review

---
 xds/internal/client/lds_test.go | 14 ++++++++++++++
 xds/internal/client/xds.go      |  6 ++++++
 2 files changed, 20 insertions(+)

diff --git a/xds/internal/client/lds_test.go b/xds/internal/client/lds_test.go
index c75ed7667d5c..32b44da1e4a3 100644
--- a/xds/internal/client/lds_test.go
+++ b/xds/internal/client/lds_test.go
@@ -119,6 +119,11 @@ func (s) TestUnmarshalListener_ClientSide(t *testing.T) {
 			Name:       "serverOnlyCustomFilter",
 			ConfigType: &v3httppb.HttpFilter_TypedConfig{TypedConfig: serverOnlyCustomFilterConfig},
 		}
+		serverOnlyOptionalCustomFilter = &v3httppb.HttpFilter{
+			Name:       "serverOnlyOptionalCustomFilter",
+			ConfigType: &v3httppb.HttpFilter_TypedConfig{TypedConfig: serverOnlyCustomFilterConfig},
+			IsOptional: true,
+		}
 		unknownFilter = &v3httppb.HttpFilter{
 			Name:       "unknownFilter",
 			ConfigType: &v3httppb.HttpFilter_TypedConfig{TypedConfig: unknownFilterConfig},
@@ -412,6 +417,15 @@ func (s) TestUnmarshalListener_ClientSide(t *testing.T) {
 			resources: []*anypb.Any{v3LisWithFilters(serverOnlyCustomFilter)},
 			wantErr:   true,
 		},
+		{
+			name:      "v3 with optional server-only filter",
+			resources: []*anypb.Any{v3LisWithFilters(serverOnlyOptionalCustomFilter)},
+			wantUpdate: map[string]ListenerUpdate{
+				v3LDSTarget: {
+					RouteConfigName: v3RouteConfigName, MaxStreamDuration: time.Second,
+				},
+			},
+		},
 		{
 			name:      "v3 with client-only filter",
 			resources: []*anypb.Any{v3LisWithFilters(clientOnlyCustomFilter)},
diff --git a/xds/internal/client/xds.go b/xds/internal/client/xds.go
index c0155609f79d..cdecbe29694e 100644
--- a/xds/internal/client/xds.go
+++ b/xds/internal/client/xds.go
@@ -223,9 +223,15 @@ func processHTTPFilters(filters []*v3httppb.HttpFilter, server bool) ([]HTTPFilt
 		}
 		if server {
 			if _, ok := httpFilter.(httpfilter.ServerInterceptorBuilder); !ok {
+				if filter.GetIsOptional() {
+					continue
+				}
 				return nil, fmt.Errorf("HTTP filter %q not supported server-side", name)
 			}
 		} else if _, ok := httpFilter.(httpfilter.ClientInterceptorBuilder); !ok {
+			if filter.GetIsOptional() {
+				continue
+			}
 			return nil, fmt.Errorf("HTTP filter %q not supported client-side", name)
 		}