Copy grpc xDS client from grpc-go

Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/traffic/xds/cds.go

@@ -0,0 +1,88 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package xds
+
+import (
+	"fmt"
+
+	xdspb "github.com/envoyproxy/go-control-plane/envoy/api/v2"
+	"github.com/golang/protobuf/ptypes"
+)
+
+// handleCDSResponse processes an CDS response received from the xDS server. On
+// receipt of a good response, it also invokes the registered watcher callback.
+func (v2c *v2Client) handleCDSResponse(resp *xdspb.DiscoveryResponse) error {
+	v2c.mu.Lock()
+	defer v2c.mu.Unlock()
+
+	wi := v2c.watchMap[cdsURL]
+	if wi == nil {
+		return fmt.Errorf("xds: no CDS watcher found when handling CDS response: %+v", resp)
+	}
+
+	var returnUpdate CDSUpdate
+	localCache := make(map[string]CDSUpdate)
+	for _, r := range resp.GetResources() {
+		var resource ptypes.DynamicAny
+		if err := ptypes.UnmarshalAny(r, &resource); err != nil {
+			return fmt.Errorf("xds: failed to unmarshal resource in CDS response: %v", err)
+		}
+		cluster, ok := resource.Message.(*xdspb.Cluster)
+		if !ok {
+			return fmt.Errorf("xds: unexpected resource type: %T in CDS response", resource.Message)
+		}
+		update, err := validateCluster(cluster)
+		if err != nil {
+			return err
+		}
+
+		// If the Cluster message in the CDS response did not contain a
+		// serviceName, we will just use the clusterName for EDS.
+		if update.ServiceName == "" {
+			update.ServiceName = cluster.GetName()
+		}
+		localCache[cluster.GetName()] = update
+		if cluster.GetName() == wi.target[0] {
+			returnUpdate = update
+		}
+	}
+	v2c.cdsCache = localCache
+
+	var err error
+	if returnUpdate.ServiceName == "" {
+		err = fmt.Errorf("xds: CDS target %s not found in received response %+v", wi.target, resp)
+	}
+	wi.stopTimer()
+	wi.callback.(cdsCallback)(returnUpdate, err)
+	return nil
+}
+
+func validateCluster(cluster *xdspb.Cluster) (CDSUpdate, error) {
+	emptyUpdate := CDSUpdate{ServiceName: ""}
+	switch {
+	case cluster.GetType() != xdspb.Cluster_EDS:
+		return emptyUpdate, fmt.Errorf("xds: unexpected cluster type %v in response: %+v", cluster.GetType(), cluster)
+	case cluster.GetEdsClusterConfig().GetEdsConfig().GetAds() == nil:
+		return emptyUpdate, fmt.Errorf("xds: unexpected edsConfig in response: %+v", cluster)
+	case cluster.GetLbPolicy() != xdspb.Cluster_ROUND_ROBIN:
+		return emptyUpdate, fmt.Errorf("xds: unexpected lbPolicy %v in response: %+v", cluster.GetLbPolicy(), cluster)
+	}
+
+	return CDSUpdate{ServiceName: cluster.GetEdsClusterConfig().GetServiceName()}, nil
+}