Return error from nghttp2_submit_{headers,request} when self dependency is made

Return NGHTTP2_ERR_INVALID_ARGUMENT from nghttp2_submit_headers() if
given stream ID and pri_spec->stream_id are the same (thus trying to
depend on itself).

Also return NGHTTP2_ERR_INVALID_ARGUMENT from nghttp2_submit_request()
and nghttp2_submit_headers() with stream_id == 1, when new stream ID
equals to pri_spec->stream_id.

Previously, these cases are not checked, and just sent to peer.

lib/includes/nghttp2/nghttp2.h

@@ -3161,6 +3161,9 @@ nghttp2_priority_spec_check_default(const nghttp2_priority_spec *pri_spec);
  * :enum:`NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE`
  *     No stream ID is available because maximum stream ID was
  *     reached.
+ * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
+ *     Trying to depend on itself (new stream ID equals
+ *     ``pri_spec->stream_id``).
  *
  * .. warning::
  *
@@ -3371,7 +3374,8 @@ NGHTTP2_EXTERN int nghttp2_submit_trailer(nghttp2_session *session,
  *     No stream ID is available because maximum stream ID was
  *     reached.
  * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
- *     The |stream_id| is 0.
+ *     The |stream_id| is 0; or trying to depend on itself (stream ID
+ *     equals ``pri_spec->stream_id``).
  * :enum:`NGHTTP2_ERR_DATA_EXIST`
  *     DATA or HEADERS has been already submitted and not fully
  *     processed yet.  This happens if stream denoted by |stream_id|

lib/nghttp2_submit.c

@@ -55,6 +55,16 @@ static int32_t submit_headers_shared(nghttp2_session *session, uint8_t flags,
     goto fail;
   }
 
+  if (stream_id == -1) {
+    if ((int32_t)session->next_stream_id == pri_spec->stream_id) {
+      rv = NGHTTP2_ERR_INVALID_ARGUMENT;
+      goto fail;
+    }
+  } else if (stream_id == pri_spec->stream_id) {
+    rv = NGHTTP2_ERR_INVALID_ARGUMENT;
+    goto fail;
+  }
+
   item = nghttp2_mem_malloc(mem, sizeof(nghttp2_outbound_item));
   if (item == NULL) {
     rv = NGHTTP2_ERR_NOMEM;

tests/nghttp2_session_test.c

@@ -3965,6 +3965,7 @@ void test_nghttp2_submit_request_without_data(void) {
   nva_out out;
   nghttp2_bufs bufs;
   nghttp2_mem *mem;
+  nghttp2_priority_spec pri_spec;
 
   mem = nghttp2_mem_default();
   frame_pack_bufs_init(&bufs);
@@ -3998,6 +3999,15 @@ void test_nghttp2_submit_request_without_data(void) {
 
   nghttp2_bufs_free(&bufs);
   nghttp2_hd_inflate_free(&inflater);
+
+  /* Try to depend on itself is error */
+  nghttp2_priority_spec_init(&pri_spec, (int32_t)session->next_stream_id, 16,
+                             0);
+
+  CU_ASSERT(NGHTTP2_ERR_INVALID_ARGUMENT ==
+            nghttp2_submit_request(session, &pri_spec, reqnv, ARRLEN(reqnv),
+                                   NULL, NULL));
+
   nghttp2_session_del(session);
 }
 
@@ -4289,6 +4299,7 @@ void test_nghttp2_submit_headers(void) {
   nva_out out;
   nghttp2_bufs bufs;
   nghttp2_mem *mem;
+  nghttp2_priority_spec pri_spec;
 
   mem = nghttp2_mem_default();
   frame_pack_bufs_init(&bufs);
@@ -4343,6 +4354,21 @@ void test_nghttp2_submit_headers(void) {
   nghttp2_frame_headers_free(&frame.headers, mem);
 
   nghttp2_hd_inflate_free(&inflater);
+
+  /* Try to depend on itself */
+  nghttp2_priority_spec_init(&pri_spec, 3, 16, 0);
+
+  CU_ASSERT(NGHTTP2_ERR_INVALID_ARGUMENT ==
+            nghttp2_submit_headers(session, NGHTTP2_FLAG_NONE, 3, &pri_spec,
+                                   reqnv, ARRLEN(reqnv), NULL));
+
+  session->next_stream_id = 5;
+  nghttp2_priority_spec_init(&pri_spec, 5, 16, 0);
+
+  CU_ASSERT(NGHTTP2_ERR_INVALID_ARGUMENT ==
+            nghttp2_submit_headers(session, NGHTTP2_FLAG_NONE, -1, &pri_spec,
+                                   reqnv, ARRLEN(reqnv), NULL));
+
   nghttp2_session_del(session);
 }