Intercept compression when workaround is active

src/core/ext/filters/workarounds/workaround_cronet_compression_filter.c

@@ -37,8 +37,8 @@
 #include <grpc/support/alloc.h>
 
 #include "src/core/ext/filters/workarounds/workaround_utils.h"
-#include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/channel/channel_stack_builder.h"
+#include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/transport/metadata.h"
 
 typedef struct call_data {
@@ -74,8 +74,8 @@ static bool get_user_agent_mdelem(const grpc_metadata_batch *batch,
 }
 
 // Callback invoked when we receive an initial metadata.
-static void recv_initial_metadata_ready(grpc_exec_ctx* exec_ctx, void* user_data,
-                                        grpc_error* error) {
+static void recv_initial_metadata_ready(grpc_exec_ctx* exec_ctx,
+                                        void* user_data, grpc_error* error) {
   grpc_call_element* elem = user_data;
   call_data* calld = elem->call_data;
 
@@ -83,7 +83,8 @@ static void recv_initial_metadata_ready(grpc_exec_ctx* exec_ctx, void* user_data
     grpc_mdelem md;
     if (get_user_agent_mdelem(calld->recv_initial_metadata, &md)) {
       grpc_user_agent_md* user_agent_md = grpc_parse_user_agent(md);
-      if (user_agent_md->workaround_active[GRPC_WORKAROUND_ID_CRONET_COMPRESSION]) {
+      if (user_agent_md
+              ->workaround_active[GRPC_WORKAROUND_ID_CRONET_COMPRESSION]) {
         calld->workaround_active = true;
       }
       // Remove with caching
@@ -92,7 +93,8 @@ static void recv_initial_metadata_ready(grpc_exec_ctx* exec_ctx, void* user_data
   }
 
   // Invoke the next callback.
-  grpc_closure_run(exec_ctx, calld->next_recv_initial_metadata_ready, GRPC_ERROR_REF(error));
+  grpc_closure_run(exec_ctx, calld->next_recv_initial_metadata_ready,
+                   GRPC_ERROR_REF(error));
 }
 
 // Start transport stream op.
@@ -105,8 +107,17 @@ static void start_transport_stream_op_batch(
   if (op->recv_initial_metadata) {
     calld->next_recv_initial_metadata_ready =
         op->payload->recv_initial_metadata.recv_initial_metadata_ready;
-    op->payload->recv_initial_metadata.recv_initial_metadata_ready = &calld->recv_initial_metadata_ready;
-    calld->recv_initial_metadata = op->payload->recv_initial_metadata.recv_initial_metadata;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->recv_initial_metadata_ready;
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+  }
+
+  if (op->send_message) {
+    /* Send message happens after client's user-agent (initial metadata) is received, so workaround_active must be set already */
+    if (calld->workaround_active) {
+      op->payload->send_message.send_message->flags |= GRPC_WRITE_NO_COMPRESS;
+    }
   }
 
   // Chain to the next filter.
@@ -120,7 +131,8 @@ static grpc_error* init_call_elem(grpc_exec_ctx* exec_ctx,
   call_data* calld = elem->call_data;
   calld->next_recv_initial_metadata_ready = NULL;
   calld->workaround_active = false;
-  grpc_closure_init(&calld->recv_initial_metadata_ready, recv_initial_metadata_ready, elem,
+  grpc_closure_init(&calld->recv_initial_metadata_ready,
+                    recv_initial_metadata_ready, elem,
                     grpc_schedule_on_exec_ctx);
   return GRPC_ERROR_NONE;
 }
@@ -173,8 +185,7 @@ static bool parse_user_agent(grpc_mdelem md) {
   }
 
   gpr_free(user_agent_str);
-  return (grpc_objc_specifier_seen &&
-          cronet_specifier_seen &&
+  return (grpc_objc_specifier_seen && cronet_specifier_seen &&
           (atol(major_version) < 1 ||
            (atol(major_version) == 1 && atol(minor_version) <= 3)));
 }
@@ -193,9 +204,8 @@ const grpc_channel_filter grpc_workaround_cronet_compression_filter = {
     grpc_channel_next_get_info,
     "workaround_cronet_compression"};
 
-static bool register_workaround_cronet_compression(grpc_exec_ctx* exec_ctx,
-                                                   grpc_channel_stack_builder* builder,
-                                                   void* arg) {
+static bool register_workaround_cronet_compression(
+    grpc_exec_ctx* exec_ctx, grpc_channel_stack_builder* builder, void* arg) {
   grpc_register_workaround(GRPC_WORKAROUND_ID_CRONET_COMPRESSION,
                            parse_user_agent);
   return grpc_channel_stack_builder_prepend_filter(
@@ -203,8 +213,8 @@ static bool register_workaround_cronet_compression(grpc_exec_ctx* exec_ctx,
 }
 
 void grpc_workaround_cronet_compression_filter_init(void) {
-  grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL,
-                                   GRPC_WORKAROUND_PRIORITY_HIGH,
+  grpc_channel_init_register_stage(
+      GRPC_SERVER_CHANNEL, GRPC_WORKAROUND_PRIORITY_HIGH,
       register_workaround_cronet_compression, NULL);
 }