Moving AudienceMetadataParser to gcp auth filter and better error han…

…dling

xds/src/main/java/io/grpc/xds/ClusterMetadataRegistry.java

@@ -18,7 +18,7 @@
 
 import com.google.protobuf.Any;
 import com.google.protobuf.InvalidProtocolBufferException;
-import io.envoyproxy.envoy.extensions.filters.http.gcp_authn.v3.Audience;
+import io.grpc.xds.GcpAuthenticationFilter.AudienceMetadataParser;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -34,11 +34,7 @@ final class ClusterMetadataRegistry {
   private final Map<String, ClusterMetadataValueParser> supportedParsers = new HashMap<>();
 
   private ClusterMetadataRegistry() {
-    registerParsers(
-        new Object[][]{
-            {"extensions.filters.http.gcp_authn.v3.Audience", new AudienceMetadataParser()},
-            // Add more parsers here as needed
-        });
+    registerParser(new AudienceMetadataParser());
   }
 
   static ClusterMetadataRegistry getInstance() {
@@ -49,16 +45,14 @@ ClusterMetadataValueParser findParser(String typeUrl) {
     return supportedParsers.get(typeUrl);
   }
 
-  private void registerParsers(Object[][] parserEntries) {
-    for (Object[] entry : parserEntries) {
-      String typeUrl = (String) entry[0];
-      ClusterMetadataValueParser parser = (ClusterMetadataValueParser) entry[1];
-      supportedParsers.put(typeUrl, parser);
-    }
+  private void registerParser(ClusterMetadataValueParser parser) {
+    supportedParsers.put(parser.getTypeUrl(), parser);
   }
 
-  @FunctionalInterface
   interface ClusterMetadataValueParser {
+
+    String getTypeUrl();
+
     /**
      * Parses the given {@link Any} object into a specific metadata value.
      *
@@ -68,23 +62,4 @@ interface ClusterMetadataValueParser {
      */
     Object parse(Any any) throws InvalidProtocolBufferException;
   }
-
-  /**
-   * Parser for Audience metadata type.
-   */
-  class AudienceMetadataParser implements ClusterMetadataValueParser {
-    @Override
-    public String parse(Any any) throws InvalidProtocolBufferException {
-      if (any.is(Audience.class)) {
-        Audience audience = any.unpack(Audience.class);
-        String url = audience.getUrl();
-        if (url.isEmpty()) {
-          throw new InvalidProtocolBufferException("Audience URL is empty.");
-        }
-        return url;
-      } else {
-        throw new InvalidProtocolBufferException("Unexpected message type: " + any.getTypeUrl());
-      }
-    }
-  }
 }

xds/src/main/java/io/grpc/xds/GcpAuthenticationFilter.java

@@ -22,6 +22,7 @@
 import com.google.protobuf.Any;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Message;
+import io.envoyproxy.envoy.extensions.filters.http.gcp_authn.v3.Audience;
 import io.envoyproxy.envoy.extensions.filters.http.gcp_authn.v3.GcpAuthnFilterConfig;
 import io.envoyproxy.envoy.extensions.filters.http.gcp_authn.v3.TokenCacheConfig;
 import io.grpc.CallCredentials;
@@ -35,6 +36,7 @@
 import io.grpc.MethodDescriptor;
 import io.grpc.Status;
 import io.grpc.auth.MoreCallCredentials;
+import io.grpc.xds.ClusterMetadataRegistry.ClusterMetadataValueParser;
 import io.grpc.xds.Filter.ClientInterceptorBuilder;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -219,4 +221,32 @@ V getOrInsert(K key, Function<K, V> create) {
       return cache.computeIfAbsent(key, create);
     }
   }
+
+  /**
+   * Parser for Audience metadata type.
+   */
+  static class AudienceMetadataParser implements ClusterMetadataValueParser {
+
+    @Override
+    public String getTypeUrl() {
+      return "extensions.filters.http.gcp_authn.v3.Audience";
+    }
+
+    @Override
+    public String parse(Any any) throws InvalidProtocolBufferException {
+      if (any.is(Audience.class)) {
+        Audience audience = any.unpack(Audience.class);
+        String url = audience.getUrl();
+        if (url.isEmpty()) {
+          throw new InvalidProtocolBufferException(
+              "Audience URL is empty. Metadata value must contain a valid URL.");
+        }
+        return url;
+      } else {
+        throw new InvalidProtocolBufferException(
+            String.format("Unexpected message type: %s. Expected: %s",
+                any.getTypeUrl(), Audience.getDescriptor().getFullName()));
+      }
+    }
+  }
 }

xds/src/main/java/io/grpc/xds/XdsClusterResource.java

@@ -179,7 +179,9 @@ static CdsUpdate processCluster(Cluster cluster,
           parseClusterMetadata(cluster.getMetadata());
       updateBuilder.parsedMetadata(parsedFilterMetadata);
     } catch (InvalidProtocolBufferException e) {
-      throw new ResourceInvalidException("xDS filter metadata invalid.");
+      throw new ResourceInvalidException(
+          "Failed to parse xDS filter metadata for cluster '" + cluster.getName() + "': "
+              + e.getMessage(), e);
     }
 
     return updateBuilder.build();
@@ -197,10 +199,6 @@ private static ImmutableMap<String, Object> parseClusterMetadata(Metadata metada
       ClusterMetadataValueParser parser = registry.findParser(value.getTypeUrl());
       if (parser != null) {
         Object parsedValue = parser.parse(value);
-        if (parsedValue == null) {
-          // parsing failed
-          throw new InvalidProtocolBufferException("Could not parse!");
-        }
         parsedMetadata.put(key, parsedValue);
       }
     }