server interceptor

Author: kannanjgithub

examples/example-oauth/src/main/java/io/grpc/examples/oauth/AuthServer.java

@@ -94,11 +94,12 @@ static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
     @Override
     public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
       // get client id added to context by interceptor
-      String clientId = Constant.CLIENT_ID_CONTEXT_KEY.get();
+      String clientId = Constant.CLIENT_ID_CONTEXT_KEY.get().get(0);
       logger.info("Processing request from " + clientId);
       HelloReply reply = HelloReply.newBuilder().setMessage("Hello, " + req.getName()).build();
       responseObserver.onNext(reply);
       responseObserver.onCompleted();
+      Constant.CLIENT_ID_CONTEXT_KEY.get().add(0, "nai");
     }
   }
 }

examples/example-oauth/src/main/java/io/grpc/examples/oauth/Constant.java

@@ -20,6 +20,7 @@
 
 import io.grpc.Context;
 import io.grpc.Metadata;
+import java.util.List;
 
 /**
  * Constants definition
@@ -28,7 +29,7 @@ final class Constant {
 
     static final String REFRESH_SUFFIX = "+1";
     static final String ACCESS_TOKEN = "access-token";
-    static final Context.Key<String> CLIENT_ID_CONTEXT_KEY = Context.key("clientId");
+    static final Context.Key<List<String>> CLIENT_ID_CONTEXT_KEY = Context.key("clientId");
     static final Metadata.Key<String> AUTHORIZATION_METADATA_KEY = Metadata.Key.of("Authorization", ASCII_STRING_MARSHALLER);
 
     private Constant() {

examples/example-oauth/src/main/java/io/grpc/examples/oauth/OAuth2ServerInterceptor.java

@@ -18,11 +18,14 @@
 
 import io.grpc.Context;
 import io.grpc.Contexts;
+import io.grpc.ForwardingServerCall.SimpleForwardingServerCall;
 import io.grpc.Metadata;
 import io.grpc.ServerCall;
 import io.grpc.ServerCallHandler;
 import io.grpc.ServerInterceptor;
 import io.grpc.Status;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * This interceptor gets the OAuth2 access token from metadata, verifies it and sets the client
@@ -54,10 +57,20 @@ public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, Re
       } else {
         String[] tokens = tokenValue.split(":");
         if (tokens.length >= 3 && tokens[2].equals(Constant.REFRESH_SUFFIX)) {
+          List<String> tokensList = new ArrayList<>();
+          tokensList.add(tokens[1]);
           // set access tokenValue into current context
           Context ctx = Context.current()
-              .withValue(Constant.CLIENT_ID_CONTEXT_KEY, tokens[1]);
-          return Contexts.interceptCall(ctx, serverCall, metadata, serverCallHandler);
+              .withValue(Constant.CLIENT_ID_CONTEXT_KEY, tokensList);
+          SimpleForwardingServerCall<ReqT, RespT> forwardingCall = new SimpleForwardingServerCall<ReqT, RespT>(
+              serverCall) {
+            @Override
+            public void sendHeaders(Metadata responseHeaders) {
+              String value = Constant.CLIENT_ID_CONTEXT_KEY.get().get(0);
+              super.sendHeaders(responseHeaders);
+            }
+          };
+          return Contexts.interceptCall(ctx,forwardingCall,metadata,serverCallHandler);
         } else {
           status = Status.UNAUTHENTICATED.withDescription("stale credentials");
         }