client: Roll-forward PR #8278(with changes): Restore the existing behavior to return io.EOF on repeated RecvMsg() calls for client-streaming RPCs (#8523)

Partially addresses: #7286

This reverts commit
20bd1e7

Changes:
- Modifies client.RecvMsg() so that successive calls after stream ends
return io.EOF.
- Adds extra state to track calls to client.recvmsg(required to return
Cardinality Violation only in case zero response)

RELEASE NOTES:
* client: Return status code INTERNAL when a server sends 0 response
messages for a unary or client streaming RPC.

Author: Pranjali-2501

stream.go

@@ -549,6 +549,8 @@ type clientStream struct {
 
 	sentLast bool // sent an end stream
 
+	receivedFirstMsg bool // set after the first message is received
+
 	methodConfig *MethodConfig
 
 	ctx context.Context // the application's context, wrapped by stats/tracing
@@ -1144,11 +1146,16 @@ func (a *csAttempt) recvMsg(m any, payInfo *payloadInfo) (err error) {
 			if statusErr := a.transportStream.Status().Err(); statusErr != nil {
 				return statusErr
 			}
+			// Received no msg and status OK for non-server streaming rpcs.
+			if !cs.desc.ServerStreams && !cs.receivedFirstMsg {
+				return status.Error(codes.Internal, "cardinality violation: received no response message from non-server-streaming RPC")
+			}
 			return io.EOF // indicates successful end of stream.
 		}
 
 		return toRPCErr(err)
 	}
+	cs.receivedFirstMsg = true
 	if a.trInfo != nil {
 		a.mu.Lock()
 		if a.trInfo.tr != nil {
@@ -1177,7 +1184,7 @@ func (a *csAttempt) recvMsg(m any, payInfo *payloadInfo) (err error) {
 	} else if err != nil {
 		return toRPCErr(err)
 	}
-	return status.Errorf(codes.Internal, "cardinality violation: expected <EOF> for non server-streaming RPCs, but received another message")
+	return status.Error(codes.Internal, "cardinality violation: expected <EOF> for non server-streaming RPCs, but received another message")
 }
 
 func (a *csAttempt) finish(err error) {
@@ -1359,6 +1366,7 @@ type addrConnStream struct {
 	transport        transport.ClientTransport
 	ctx              context.Context
 	sentLast         bool
+	receivedFirstMsg bool
 	desc             *StreamDesc
 	codec            baseCodec
 	sendCompressorV0 Compressor
@@ -1484,10 +1492,15 @@ func (as *addrConnStream) RecvMsg(m any) (err error) {
 			if statusErr := as.transportStream.Status().Err(); statusErr != nil {
 				return statusErr
 			}
+			// Received no msg and status OK for non-server streaming rpcs.
+			if !as.desc.ServerStreams && !as.receivedFirstMsg {
+				return status.Error(codes.Internal, "cardinality violation: received no response message from non-server-streaming RPC")
+			}
 			return io.EOF // indicates successful end of stream.
 		}
 		return toRPCErr(err)
 	}
+	as.receivedFirstMsg = true
 
 	if as.desc.ServerStreams {
 		// Subsequent messages should be received by subsequent RecvMsg calls.
@@ -1501,7 +1514,7 @@ func (as *addrConnStream) RecvMsg(m any) (err error) {
 	} else if err != nil {
 		return toRPCErr(err)
 	}
-	return status.Errorf(codes.Internal, "cardinality violation: expected <EOF> for non server-streaming RPCs, but received another message")
+	return status.Error(codes.Internal, "cardinality violation: expected <EOF> for non server-streaming RPCs, but received another message")
 }
 
 func (as *addrConnStream) finish(err error) {

test/end2end_test.go

@@ -3590,9 +3590,6 @@ func testClientStreamingError(t *testing.T, e env) {
 // Tests that a client receives a cardinality violation error for client-streaming
 // RPCs if the server doesn't send a message before returning status OK.
 func (s) TestClientStreamingCardinalityViolation_ServerHandlerMissingSendAndClose(t *testing.T) {
-	// TODO : https://github.com/grpc/grpc-go/issues/8119 - remove `t.Skip()`
-	// after this is fixed.
-	t.Skip()
 	ss := &stubserver.StubServer{
 		StreamingInputCallF: func(_ testgrpc.TestService_StreamingInputCallServer) error {
 			// Returning status OK without sending a response message.This is a
@@ -3741,6 +3738,165 @@ func (s) TestClientStreaming_ReturnErrorAfterSendAndClose(t *testing.T) {
 	}
 }
 
+// Tests that client receives a cardinality violation error for unary
+// RPCs if the server doesn't send a message before returning status OK.
+func (s) TestUnaryRPC_ServerSendsOnlyTrailersWithOK(t *testing.T) {
+	lis, err := testutils.LocalTCPListener()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer lis.Close()
+
+	ss := grpc.UnknownServiceHandler(func(any, grpc.ServerStream) error {
+		return nil
+	})
+
+	s := grpc.NewServer(ss)
+	go s.Serve(lis)
+	defer s.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	cc, err := grpc.NewClient(lis.Addr().String(), grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		t.Fatalf("grpc.NewClient(%q) failed unexpectedly: %v", lis.Addr(), err)
+	}
+	defer cc.Close()
+
+	client := testgrpc.NewTestServiceClient(cc)
+	if _, err = client.EmptyCall(ctx, &testpb.Empty{}); status.Code(err) != codes.Internal {
+		t.Errorf("stream.RecvMsg() = %v, want error %v", status.Code(err), codes.Internal)
+	}
+}
+
+// Tests the behavior for unary RPC when client calls RecvMsg() twice.
+// Second call to RecvMsg should fail with io.EOF.
+func (s) TestUnaryRPC_ClientCallRecvMsgTwice(t *testing.T) {
+	e := tcpTLSEnv
+	te := newTest(t, e)
+	defer te.tearDown()
+
+	te.startServer(&testServer{security: e.security})
+
+	cc := te.clientConn()
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+
+	desc := &grpc.StreamDesc{
+		StreamName:    "UnaryCall",
+		ServerStreams: false,
+		ClientStreams: false,
+	}
+	stream, err := cc.NewStream(ctx, desc, "/grpc.testing.TestService/UnaryCall")
+	if err != nil {
+		t.Fatalf("cc.NewStream() failed unexpectedly: %v", err)
+	}
+
+	if err := stream.SendMsg(&testpb.SimpleRequest{}); err != nil {
+		t.Fatalf("stream.SendMsg(_) = %v, want <nil>", err)
+	}
+
+	resp := &testpb.SimpleResponse{}
+	if err := stream.RecvMsg(resp); err != nil {
+		t.Fatalf("stream.RecvMsg() = %v , want <nil>", err)
+	}
+
+	if err = stream.RecvMsg(resp); err != io.EOF {
+		t.Errorf("stream.RecvMsg() = %v, want error %v", err, io.EOF)
+	}
+}
+
+// Tests the behavior for unary RPC when server calls SendMsg() twice.
+// Client should fail with cardinality violation error.
+func (s) TestUnaryRPC_ServerCallSendMsgTwice(t *testing.T) {
+	lis, err := testutils.LocalTCPListener()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer lis.Close()
+
+	s := grpc.NewServer()
+	serviceDesc := grpc.ServiceDesc{
+		ServiceName: "grpc.testing.TestService",
+		HandlerType: (*any)(nil),
+		Methods:     []grpc.MethodDesc{},
+		Streams: []grpc.StreamDesc{
+			{
+				StreamName: "UnaryCall",
+				Handler: func(_ any, stream grpc.ServerStream) error {
+					if err := stream.RecvMsg(&testpb.Empty{}); err != nil {
+						t.Errorf("stream.RecvMsg() = %v, want <nil>", err)
+					}
+
+					if err = stream.SendMsg(&testpb.Empty{}); err != nil {
+						t.Errorf("stream.SendMsg() = %v, want <nil>", err)
+					}
+
+					if err = stream.SendMsg(&testpb.Empty{}); err != nil {
+						t.Errorf("stream.SendMsg() = %v, want <nil>", err)
+					}
+					return nil
+				},
+				ClientStreams: false,
+				ServerStreams: false,
+			},
+		},
+	}
+	s.RegisterService(&serviceDesc, &testServer{})
+	go s.Serve(lis)
+	defer s.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	cc, err := grpc.NewClient(lis.Addr().String(), grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		t.Fatalf("grpc.NewClient(%q) failed unexpectedly: %v", lis.Addr(), err)
+	}
+	defer cc.Close()
+
+	client := testgrpc.NewTestServiceClient(cc)
+	if _, err = client.UnaryCall(ctx, &testpb.SimpleRequest{}); status.Code(err) != codes.Internal {
+		t.Errorf("stream.RecvMsg() = %v, want error %v", status.Code(err), codes.Internal)
+	}
+}
+
+// Tests the behavior for client-streaming RPC when client calls RecvMsg() twice.
+// Second call to RecvMsg should fail with io.EOF.
+func (s) TestClientStreaming_ClientCallRecvMsgTwice(t *testing.T) {
+	ss := stubserver.StubServer{
+		StreamingInputCallF: func(stream testgrpc.TestService_StreamingInputCallServer) error {
+			if err := stream.SendAndClose(&testpb.StreamingInputCallResponse{}); err != nil {
+				t.Errorf("stream.SendAndClose(_) = %v, want <nil>", err)
+			}
+			return nil
+		},
+	}
+	if err := ss.Start(nil); err != nil {
+		t.Fatal("Error starting server:", err)
+	}
+	defer ss.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	stream, err := ss.Client.StreamingInputCall(ctx)
+	if err != nil {
+		t.Fatalf(".StreamingInputCall(_) = _, %v, want <nil>", err)
+	}
+	if err := stream.Send(&testpb.StreamingInputCallRequest{}); err != nil {
+		t.Fatalf("stream.Send(_) = %v, want <nil>", err)
+	}
+	if err := stream.CloseSend(); err != nil {
+		t.Fatalf("stream.CloseSend() = %v, want <nil>", err)
+	}
+	resp := new(testpb.StreamingInputCallResponse)
+	if err := stream.RecvMsg(resp); err != nil {
+		t.Fatalf("stream.RecvMsg() = %v , want <nil>", err)
+	}
+	if err = stream.RecvMsg(resp); err != io.EOF {
+		t.Errorf("stream.RecvMsg() = %v, want error %v", err, io.EOF)
+	}
+}
+
 // Tests the behavior for server-side streaming when client calls SendMsg twice.
 // Second call to SendMsg should fail with Internal error and result in closing
 // the connection with a RST_STREAM.
@@ -3802,7 +3958,6 @@ func (s) TestServerStreaming_ClientCallSendMsgTwice(t *testing.T) {
 	<-handlerDone
 }
 
-// TODO(i/7286) : Add tests to check server-side behavior for Unary RPC.
 // Tests the behavior for unary RPC when client calls SendMsg twice. Second call
 // to SendMsg should fail with Internal error.
 func (s) TestUnaryRPC_ClientCallSendMsgTwice(t *testing.T) {
@@ -3981,7 +4136,7 @@ func (s) TestServerStreaming_ClientSendsZeroRequests(t *testing.T) {
 }
 
 // Tests that a client receives a cardinality violation error for client-streaming
-// RPCs if the server call SendMsg multiple times.
+// RPCs if the server calls SendMsg() multiple times.
 func (s) TestClientStreaming_ServerHandlerSendMsgAfterSendMsg(t *testing.T) {
 	ss := stubserver.StubServer{
 		StreamingInputCallF: func(stream testgrpc.TestService_StreamingInputCallServer) error {