golang filter: add VirtualClusterName getter (envoyproxy#28406)

Add a new method to get matched virtual cluster name
Risk Level: Low
Testing: Integration
Docs Changes:
Release Notes:
Platform Specific Features:

Signed-off-by: spacewander <[email protected]>

contrib/golang/common/go/api/filter.go

@@ -115,6 +115,8 @@ type StreamInfo interface {
 	UpstreamClusterName() (string, bool)
 	// FilterState return the filter state interface.
 	FilterState() FilterState
+	// VirtualClusterName returns the name of the virtual cluster which got matched
+	VirtualClusterName() (string, bool)
 }
 
 type StreamFilterCallbacks interface {

contrib/golang/filters/http/source/go/pkg/http/capi_impl.go

@@ -55,6 +55,7 @@ const (
 	ValueDownstreamRemoteAddress = 8
 	ValueUpstreamHostAddress     = 9
 	ValueUpstreamClusterName     = 10
+	ValueVirtualClusterName      = 11
 )
 
 type httpCApiImpl struct{}

contrib/golang/filters/http/source/go/pkg/http/filter.go

@@ -209,6 +209,10 @@ func (s *streamInfo) UpstreamClusterName() (string, bool) {
 	return cAPI.HttpGetStringValue(unsafe.Pointer(s.request), ValueUpstreamClusterName)
 }
 
+func (s *streamInfo) VirtualClusterName() (string, bool) {
+	return cAPI.HttpGetStringValue(unsafe.Pointer(s.request), ValueVirtualClusterName)
+}
+
 type filterState struct {
 	request *httpRequest
 }

contrib/golang/filters/http/source/golang_filter.cc

@@ -1009,6 +1009,12 @@ CAPIStatus Filter::getStringValue(int id, GoString* value_str) {
       return CAPIStatus::CAPIValueNotFound;
     }
     break;
+  case EnvoyValue::VirtualClusterName:
+    if (!state.streamInfo().virtualClusterName().has_value()) {
+      return CAPIStatus::CAPIValueNotFound;
+    }
+    req_->strValue = state.streamInfo().virtualClusterName().value();
+    break;
   default:
     RELEASE_ASSERT(false, absl::StrCat("invalid string value id: ", id));
   }

contrib/golang/filters/http/source/golang_filter.h

@@ -107,6 +107,7 @@ enum class EnvoyValue {
   DownstreamRemoteAddress,
   UpstreamHostAddress,
   UpstreamClusterName,
+  VirtualClusterName,
 };
 
 struct httpRequestInternal;

contrib/golang/filters/http/test/golang_integration_test.cc

@@ -152,6 +152,15 @@ name: golang
           hcm.mutable_route_config()->mutable_virtual_hosts(0)->mutable_routes(0)->set_name(
               "test-route-name");
           hcm.mutable_route_config()->mutable_virtual_hosts(0)->set_domains(0, domain);
+
+          auto* virtual_cluster =
+              hcm.mutable_route_config()->mutable_virtual_hosts(0)->add_virtual_clusters();
+          virtual_cluster->set_name("test_vcluster");
+          auto* headers = virtual_cluster->add_headers();
+          // use test_vcluster if presents
+          headers->set_name("existed-header");
+          headers->set_present_match(true);
+
           hcm.mutable_route_config()
               ->mutable_virtual_hosts(0)
               ->mutable_routes(0)
@@ -372,6 +381,9 @@ name: golang
     // check response attempt count in encode phase
     EXPECT_EQ("1", getHeader(response->headers(), "rsp-attempt-count"));
 
+    // check virtual cluster name
+    EXPECT_EQ("test_vcluster", getHeader(response->headers(), "rsp-virtual-cluster-name"));
+
     // verify response status
     EXPECT_EQ("200", getHeader(response->headers(), "rsp-status"));
 

contrib/golang/filters/http/test/test_data/basic/filter.go

@@ -293,6 +293,11 @@ func (f *filter) encodeHeaders(header api.ResponseHeaderMap, endStream bool) api
 	header.Set("rsp-route-name", f.callbacks.StreamInfo().GetRouteName())
 	header.Set("rsp-filter-chain-name", f.callbacks.StreamInfo().FilterChainName())
 	header.Set("rsp-attempt-count", strconv.Itoa(int(f.callbacks.StreamInfo().AttemptCount())))
+	if name, ok := f.callbacks.StreamInfo().VirtualClusterName(); ok {
+		header.Set("rsp-virtual-cluster-name", name)
+	} else {
+		header.Set("rsp-virtual-cluster-name", "not found")
+	}
 
 	if f.panic == "encode-header" {
 		badcode()