[gateway/xds] Allow underscores in HTTP headers

Author: dilyevsky

pkg/gateway/xds/translator/listener.go

@@ -232,7 +232,9 @@ func (t *Translator) addXdsHTTPFilterChain(xdsListener *listenerv3.Listener, irL
 MergeSlashes: irListener.Path.MergeSlashes,
 PathWithEscapedSlashesAction: translateEscapePath(irListener.Path.EscapedSlashesAction),
 CommonHttpProtocolOptions: &corev3.HttpProtocolOptions{
-HeadersWithUnderscoresAction: corev3.HttpProtocolOptions_REJECT_REQUEST,
+// Envoy's default is ALLOW. This is also consistent with most
+// CDN proxies.
+HeadersWithUnderscoresAction: corev3.HttpProtocolOptions_ALLOW,
 },
 GenerateRequestId: &wrappers.BoolValue{Value: hcmTracing != nil},
 Tracing: hcmTracing,