Merge pull request #16558 from ncteisen/user-agent

Stop Unconditionally Surfacing User Agent to Server

2 files changed, 19 insertions, 1 deletions

diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index b5353c1dea..5f3b96f40b 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -342,6 +342,9 @@ typedef struct {
   "grpc.disable_client_authority_filter"
 /** If set to zero, disables use of http proxies. Enabled by default. */
 #define GRPC_ARG_ENABLE_HTTP_PROXY "grpc.enable_http_proxy"
+/** If set to non zero, surfaces the user agent string to the server. User
+    agent is surfaced by default. */
+#define GRPC_ARG_SURFACE_USER_AGENT "grpc.surface_user_agent"
 /** \} */
 
 /** Result of a grpc call. If the caller satisfies the prerequisites of a
diff --git a/src/core/ext/filters/http/server/http_server_filter.cc b/src/core/ext/filters/http/server/http_server_filter.cc
index 926afeec84..1b3426b120 100644
--- a/src/core/ext/filters/http/server/http_server_filter.cc
+++ b/src/core/ext/filters/http/server/http_server_filter.cc
@@ -23,6 +23,7 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <string.h>
+#include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/b64.h"
@@ -66,6 +67,10 @@ struct call_data {
   grpc_closure* original_recv_trailing_metadata_ready;
 };
 
+struct channel_data {
+  bool surface_user_agent;
+};
+
 }  // namespace
 
 static grpc_error* hs_filter_outgoing_metadata(grpc_call_element* elem,
@@ -262,6 +267,11 @@ static grpc_error* hs_filter_incoming_metadata(grpc_call_element* elem,
             GRPC_ERROR_STR_KEY, grpc_slice_from_static_string(":authority")));
   }
 
+  channel_data* chand = static_cast<channel_data*>(elem->channel_data);
+  if (!chand->surface_user_agent && b->idx.named.user_agent != nullptr) {
+    grpc_metadata_batch_remove(b, b->idx.named.user_agent);
+  }
+
   return error;
 }
 
@@ -430,7 +440,12 @@ static void hs_destroy_call_elem(grpc_call_element* elem,
 /* Constructor for channel_data */
 static grpc_error* hs_init_channel_elem(grpc_channel_element* elem,
                                         grpc_channel_element_args* args) {
+  channel_data* chand = static_cast<channel_data*>(elem->channel_data);
   GPR_ASSERT(!args->is_last);
+  chand->surface_user_agent = grpc_channel_arg_get_bool(
+      grpc_channel_args_find(args->channel_args,
+                             const_cast<char*>(GRPC_ARG_SURFACE_USER_AGENT)),
+      true);
   return GRPC_ERROR_NONE;
 }
 
@@ -444,7 +459,7 @@ const grpc_channel_filter grpc_http_server_filter = {
     hs_init_call_elem,
     grpc_call_stack_ignore_set_pollset_or_pollset_set,
     hs_destroy_call_elem,
-    0,
+    sizeof(channel_data),
     hs_init_channel_elem,
     hs_destroy_channel_elem,
     grpc_channel_next_get_info,