Remove code submitting WINDOW_UPDATE with negative delta

It is effectively dead code because we should have already submit
WINDOW_UPDATE before this case happens.

lib/nghttp2_helper.c

@@ -118,7 +118,8 @@ int nghttp2_adjust_local_window_size(int32_t *local_window_size_ptr,
         *recv_window_size_ptr += recv_reduction_diff;
       } else {
         /* If *recv_window_size_ptr > 0, then those bytes are
-           considered to be backed to the remote peer, so it is
+           considered to be backed to the remote peer (by
+           WINDOW_UPDATE with the adjusted *delta_ptr), so it is
            effectively 0 now. */
         *recv_window_size_ptr = recv_reduction_diff;
       }
@@ -142,6 +143,7 @@ int nghttp2_adjust_local_window_size(int32_t *local_window_size_ptr,
     *local_window_size_ptr += *delta_ptr;
     *recv_window_size_ptr += *delta_ptr;
     *recv_reduction_ptr -= *delta_ptr;
+    *delta_ptr = 0;
   }
   return 0;
 }

lib/nghttp2_session.h

@@ -171,7 +171,8 @@ struct nghttp2_session {
      current initial window size of remote endpoint. */
   int32_t remote_window_size;
   /* Keep track of the number of bytes received without
-     WINDOW_UPDATE. */
+     WINDOW_UPDATE. This could be negative after submitting negative
+     value to WINDOW_UPDATE. */
   int32_t recv_window_size;
   /* The amount of recv_window_size cut using submitting negative
      value to WINDOW_UPDATE */

lib/nghttp2_stream.h

@@ -113,7 +113,8 @@ typedef struct {
      current initial window size of remote endpoint. */
   int32_t remote_window_size;
   /* Keep track of the number of bytes received without
-     WINDOW_UPDATE. */
+     WINDOW_UPDATE. This could be negative after submitting negative
+     value to WINDOW_UPDATE */
   int32_t recv_window_size;
   /* The amount of recv_window_size cut using submitting negative
      value to WINDOW_UPDATE */

lib/nghttp2_submit.c

@@ -269,14 +269,6 @@ int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
     if(rv != 0) {
       return rv;
     }
-    if(!(session->opt_flags &
-         NGHTTP2_OPTMASK_NO_AUTO_CONNECTION_WINDOW_UPDATE) &&
-       window_size_increment < 0 &&
-       nghttp2_should_send_window_update(session->local_window_size,
-                                         session->recv_window_size)) {
-      window_size_increment = session->recv_window_size;
-      session->recv_window_size = 0;
-    }
   } else {
     stream = nghttp2_session_get_stream(session, stream_id);
     if(stream) {
@@ -290,14 +282,6 @@ int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
       if(rv != 0) {
         return rv;
       }
-      if(!(session->opt_flags &
-           NGHTTP2_OPTMASK_NO_AUTO_STREAM_WINDOW_UPDATE) &&
-         window_size_increment < 0 &&
-         nghttp2_should_send_window_update(stream->local_window_size,
-                                           stream->recv_window_size)) {
-        window_size_increment = stream->recv_window_size;
-        stream->recv_window_size = 0;
-      }
     } else {
       return NGHTTP2_ERR_STREAM_CLOSED;
     }

tests/nghttp2_helper_test.c

@@ -83,7 +83,7 @@ void test_nghttp2_adjust_local_window_size(void)
   CU_ASSERT(100 == local_window_size);
   CU_ASSERT(-1 == recv_window_size);
   CU_ASSERT(1 == recv_reduction);
-  CU_ASSERT(-1 == delta);
+  CU_ASSERT(0 == delta);
 
   delta = 1;
   CU_ASSERT(0 == nghttp2_adjust_local_window_size(&local_window_size,

tests/nghttp2_session_test.c

@@ -2508,23 +2508,21 @@ void test_nghttp2_submit_window_update_local_window_size(void)
   CU_ASSERT(0 == nghttp2_session_send(session));
 
   /* Let's decrement local window size */
-  stream->recv_window_size = 65536;
+  stream->recv_window_size = 4096;
   CU_ASSERT(0 == nghttp2_submit_window_update(session, NGHTTP2_FLAG_NONE, 2,
                                               -stream->local_window_size / 2));
   CU_ASSERT(32768 == stream->local_window_size);
-  CU_ASSERT(0 == stream->recv_window_size);
+  CU_ASSERT(-28672 == stream->recv_window_size);
   CU_ASSERT(32768 == stream->recv_reduction);
 
   item = nghttp2_session_get_next_ob_item(session);
-  CU_ASSERT(NGHTTP2_WINDOW_UPDATE == OB_CTRL_TYPE(item));
-  CU_ASSERT(32768 == OB_CTRL(item)->window_update.window_size_increment);
-  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(item == NULL);
 
   /* Increase local window size */
   CU_ASSERT(0 == nghttp2_submit_window_update(session, NGHTTP2_FLAG_NONE, 2,
                                               16384));
   CU_ASSERT(49152 == stream->local_window_size);
-  CU_ASSERT(16384 == stream->recv_window_size);
+  CU_ASSERT(-12288 == stream->recv_window_size);
   CU_ASSERT(16384 == stream->recv_reduction);
   CU_ASSERT(NULL == nghttp2_session_get_next_ob_item(session));
 
@@ -2548,22 +2546,20 @@ void test_nghttp2_submit_window_update_local_window_size(void)
   CU_ASSERT(0 == nghttp2_session_send(session));
 
   /* Go decrement part */
-  session->recv_window_size = 65536;
+  session->recv_window_size = 4096;
   CU_ASSERT(0 == nghttp2_submit_window_update(session, NGHTTP2_FLAG_NONE, 0,
                                               -session->local_window_size/2));
   CU_ASSERT(32768 == session->local_window_size);
-  CU_ASSERT(0 == session->recv_window_size);
+  CU_ASSERT(-28672 == session->recv_window_size);
   CU_ASSERT(32768 == session->recv_reduction);
   item = nghttp2_session_get_next_ob_item(session);
-  CU_ASSERT(NGHTTP2_WINDOW_UPDATE == OB_CTRL_TYPE(item));
-  CU_ASSERT(32768 == OB_CTRL(item)->window_update.window_size_increment);
-  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(item == NULL);
 
   /* Increase local window size */
   CU_ASSERT(0 == nghttp2_submit_window_update(session, NGHTTP2_FLAG_NONE, 0,
                                               16384));
   CU_ASSERT(49152 == session->local_window_size);
-  CU_ASSERT(16384 == session->recv_window_size);
+  CU_ASSERT(-12288 == session->recv_window_size);
   CU_ASSERT(16384 == session->recv_reduction);
   CU_ASSERT(NULL == nghttp2_session_get_next_ob_item(session));