1 files changed, 18 insertions, 2 deletions

diff --git a/src/core/lib/surface/call.c b/src/core/lib/surface/call.c
index d63a4a7401..77ad410b50 100644
--- a/src/core/lib/surface/call.c
+++ b/src/core/lib/surface/call.c
@@ -174,6 +174,9 @@ struct grpc_call {
   /* Received call statuses from various sources */
   received_status status[STATUS_SOURCE_COUNT];
 
+  /* Call stats: only valid after trailing metadata received */
+  grpc_transport_stream_stats stats;
+
   /* Compression algorithm for the call */
   grpc_compression_algorithm compression_algorithm;
   /* Supported encodings (compression algorithms), a bitset */
@@ -909,7 +912,7 @@ static void set_cancelled_value(grpc_status_code status, void *dest) {
   *(int *)dest = (status != GRPC_STATUS_OK);
 }
 
-static int are_write_flags_valid(uint32_t flags) {
+static bool are_write_flags_valid(uint32_t flags) {
   /* check that only bits in GRPC_WRITE_(INTERNAL?)_USED_MASK are set */
   const uint32_t allowed_write_positions =
       (GRPC_WRITE_USED_MASK | GRPC_WRITE_INTERNAL_USED_MASK);
@@ -917,6 +920,15 @@ static int are_write_flags_valid(uint32_t flags) {
   return !(flags & invalid_positions);
 }
 
+static bool are_initial_metadata_flags_valid(uint32_t flags, bool is_client) {
+  /* check that only bits in GRPC_WRITE_(INTERNAL?)_USED_MASK are set */
+  uint32_t invalid_positions = ~GRPC_INITIAL_METADATA_USED_MASK;
+  if (!is_client) {
+    invalid_positions |= GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST;
+  }
+  return !(flags & invalid_positions);
+}
+
 static batch_control *allocate_batch_control(grpc_call *call) {
   size_t i;
   for (i = 0; i < MAX_CONCURRENT_BATCHES; i++) {
@@ -1196,7 +1208,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
     switch (op->op) {
       case GRPC_OP_SEND_INITIAL_METADATA:
         /* Flag validation: currently allow no flags */
-        if (op->flags != 0) {
+        if (!are_initial_metadata_flags_valid(op->flags, call->is_client)) {
           error = GRPC_CALL_ERROR_INVALID_FLAGS;
           goto done_with_error;
         }
@@ -1220,6 +1232,8 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         call->metadata_batch[0][0].deadline = call->send_deadline;
         stream_op.send_initial_metadata =
             &call->metadata_batch[0 /* is_receiving */][0 /* is_trailing */];
+        stream_op.send_idempotent_request =
+            (op->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) != 0;
         break;
       case GRPC_OP_SEND_MESSAGE:
         if (!are_write_flags_valid(op->flags)) {
@@ -1371,6 +1385,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         bctl->recv_final_op = 1;
         stream_op.recv_trailing_metadata =
             &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
+        stream_op.collect_stats = &call->stats;
         break;
       case GRPC_OP_RECV_CLOSE_ON_SERVER:
         /* Flag validation: currently allow no flags */
@@ -1392,6 +1407,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         bctl->recv_final_op = 1;
         stream_op.recv_trailing_metadata =
             &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
+        stream_op.collect_stats = &call->stats;
         break;
     }
   }