Add int return value to on_data_send_callback

lib/includes/nghttp2/nghttp2.h

@@ -893,8 +893,13 @@ typedef int (*nghttp2_on_frame_not_send_callback)
  * @functypedef
  *
  * Callback function invoked after DATA frame is sent.
+ *
+ * The implementation of this function must return 0 if it
+ * succeeds. If nonzero is returned, it is treated as fatal error and
+ * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
+ * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
-typedef void (*nghttp2_on_data_send_callback)
+typedef int (*nghttp2_on_data_send_callback)
 (nghttp2_session *session, uint16_t length, uint8_t flags, int32_t stream_id,
  void *user_data);
 

lib/nghttp2_session.c

@@ -1355,13 +1355,15 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
     nghttp2_data *data_frame;
     data_frame = nghttp2_outbound_item_get_data_frame(session->aob.item);
     if(session->callbacks.on_data_send_callback) {
-      session->callbacks.on_data_send_callback
-        (session,
-         session->aob.framebuflen - NGHTTP2_FRAME_HEAD_LENGTH,
-         data_frame->eof ? data_frame->hd.flags :
-         (data_frame->hd.flags & (~NGHTTP2_FLAG_END_STREAM)),
-         data_frame->hd.stream_id,
-         session->user_data);
+      if(session->callbacks.on_data_send_callback
+         (session,
+          session->aob.framebuflen - NGHTTP2_FRAME_HEAD_LENGTH,
+          data_frame->eof ? data_frame->hd.flags :
+          (data_frame->hd.flags & (~NGHTTP2_FLAG_END_STREAM)),
+          data_frame->hd.stream_id,
+          session->user_data) != 0) {
+        return NGHTTP2_ERR_CALLBACK_FAILURE;
+      }
     }
     if(data_frame->eof && (data_frame->hd.flags & NGHTTP2_FLAG_END_STREAM)) {
       nghttp2_stream *stream =

src/HttpServer.cc

@@ -778,7 +778,7 @@ int hd_on_data_recv_callback
 } // namespace
 
 namespace {
-void hd_on_data_send_callback
+int hd_on_data_send_callback
 (nghttp2_session *session, uint16_t length,  uint8_t flags, int32_t stream_id,
  void *user_data)
 {
@@ -787,6 +787,7 @@ void hd_on_data_send_callback
     print_session_id(hd->session_id());
     on_data_send_callback(session, length, flags, stream_id, user_data);
   }
+  return 0;
 }
 } // namespace
 

src/app_helper.cc

@@ -425,7 +425,7 @@ int on_data_recv_callback
   return 0;
 }
 
-void on_data_send_callback
+int on_data_send_callback
 (nghttp2_session *session, uint16_t length, uint8_t flags, int32_t stream_id,
  void *user_data)
 {
@@ -433,6 +433,7 @@ void on_data_send_callback
   printf(" send ");
   print_data_frame(PRINT_SEND, length, flags, stream_id);
   fflush(stdout);
+  return 0;
 }
 
 int64_t time_delta(const timeval& a, const timeval& b)

src/app_helper.h

@@ -68,7 +68,7 @@ int on_data_recv_callback
 (nghttp2_session *session, uint16_t length, uint8_t flags, int32_t stream_id,
  void *user_data);
 
-void on_data_send_callback
+int on_data_send_callback
 (nghttp2_session *session, uint16_t length, uint8_t flags, int32_t stream_id,
  void *user_data);