Merge pull request #16562 from yashykt/statusgrpc

Prefer grpc status over http status

src/core/ext/filters/http/client/http_client_filter.cc

@@ -79,7 +79,12 @@ struct channel_data {
 static grpc_error* client_filter_incoming_metadata(grpc_call_element* elem,
                                                    grpc_metadata_batch* b) {
   if (b->idx.named.status != nullptr) {
-    if (grpc_mdelem_eq(b->idx.named.status->md, GRPC_MDELEM_STATUS_200)) {
+    /* If both gRPC status and HTTP status are provided in the response, we
+     * should prefer the gRPC status code, as mentioned in
+     * https://github.com/grpc/grpc/blob/master/doc/http-grpc-status-mapping.md.
+     */
+    if (b->idx.named.grpc_status != nullptr ||
+        grpc_mdelem_eq(b->idx.named.status->md, GRPC_MDELEM_STATUS_200)) {
       grpc_metadata_batch_remove(b, b->idx.named.status);
     } else {
       char* val = grpc_dump_slice(GRPC_MDVALUE(b->idx.named.status->md),

test/core/end2end/tests/filter_status_code.cc

@@ -16,6 +16,14 @@
  *
  */
 
+/* This test verifies -
+ * 1) grpc_call_final_info passed to the filters on destroying a call contains
+ * the proper status.
+ * 2) If the response has both an HTTP status code and a gRPC status code, then
+ * we should prefer the gRPC status code as mentioned in
+ * https://github.com/grpc/grpc/blob/master/doc/http-grpc-status-mapping.md
+ */
+
 #include "test/core/end2end/end2end_tests.h"
 
 #include <limits.h>
@@ -249,6 +257,22 @@ typedef struct final_status_data {
   grpc_call_stack* call;
 } final_status_data;
 
+static void server_start_transport_stream_op_batch(
+    grpc_call_element* elem, grpc_transport_stream_op_batch* op) {
+  auto* data = static_cast<final_status_data*>(elem->call_data);
+  if (data->call == g_server_call_stack) {
+    if (op->send_initial_metadata) {
+      auto* batch = op->payload->send_initial_metadata.send_initial_metadata;
+      if (batch->idx.named.status != nullptr) {
+        /* Replace the HTTP status with 404 */
+        grpc_metadata_batch_substitute(batch, batch->idx.named.status,
+                                       GRPC_MDELEM_STATUS_404);
+      }
+    }
+  }
+  grpc_call_next_op(elem, op);
+}
+
 static grpc_error* init_call_elem(grpc_call_element* elem,
                                   const grpc_call_element_args* args) {
   final_status_data* data = static_cast<final_status_data*>(elem->call_data);
@@ -307,7 +331,7 @@ static const grpc_channel_filter test_client_filter = {
     "client_filter_status_code"};
 
 static const grpc_channel_filter test_server_filter = {
-    grpc_call_next_op,
+    server_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(final_status_data),
     init_call_elem,