Use largest valid stream ID which passed to callback as last-stream-ID

Previously we use largest stream ID received so far as last-stream-ID,
and it is irrevant that it is passed to the callback (thus upper layer).
Now the stream ID which is passed to callback is eligible to
last-stream-ID.

lib/nghttp2_session.c

@@ -190,8 +190,8 @@ static int nghttp2_session_new(nghttp2_session **session_ptr,
   }
   memset(*session_ptr, 0, sizeof(nghttp2_session));
 
-  /* next_stream_id and last_recv_stream_id are initialized in either
-     nghttp2_session_client_new or nghttp2_session_server_new */
+  /* next_stream_id is initialized in either
+     nghttp2_session_client_new2 or nghttp2_session_server_new2 */
 
   (*session_ptr)->next_seq = 0;
 
@@ -325,7 +325,6 @@ int nghttp2_session_client_new2(nghttp2_session **session_ptr,
   if(r == 0) {
     /* IDs for use in client */
     (*session_ptr)->next_stream_id = 1;
-    (*session_ptr)->last_recv_stream_id = 0;
   }
   return r;
 }
@@ -351,7 +350,6 @@ int nghttp2_session_server_new2(nghttp2_session **session_ptr,
   if(r == 0) {
     /* IDs for use in client */
     (*session_ptr)->next_stream_id = 2;
-    (*session_ptr)->last_recv_stream_id = 0;
   }
   return r;
 }
@@ -1919,6 +1917,7 @@ int nghttp2_session_on_request_headers_received(nghttp2_session *session,
   if(!stream) {
     return NGHTTP2_ERR_NOMEM;
   }
+  session->last_proc_stream_id = session->last_recv_stream_id;
   rv = nghttp2_session_call_on_frame_received(session, frame);
   if(rv != 0) {
     return rv;
@@ -2588,6 +2587,7 @@ int nghttp2_session_on_push_promise_received(nghttp2_session *session,
   if(!promised_stream) {
     return NGHTTP2_ERR_NOMEM;
   }
+  session->last_proc_stream_id = session->last_recv_stream_id;
   return nghttp2_session_call_on_frame_received(session, frame);
 }
 
@@ -3723,6 +3723,7 @@ int nghttp2_session_upgrade(nghttp2_session *session,
   if(session->server) {
     nghttp2_stream_shutdown(stream, NGHTTP2_SHUT_RD);
     session->last_recv_stream_id = 1;
+    session->last_proc_stream_id = 1;
   } else {
     nghttp2_stream_shutdown(stream, NGHTTP2_SHUT_WR);
     session->next_stream_id += 2;

lib/nghttp2_session.h

@@ -118,7 +118,12 @@ struct nghttp2_session {
   uint8_t server;
   /* Next Stream ID. Made unsigned int to detect >= (1 << 31). */
   uint32_t next_stream_id;
+  /* The largest stream ID received so far */
   int32_t last_recv_stream_id;
+  /* The largest stream ID which has been processed in some way. This
+     value will be used as last-stream-id when sending GOAWAY
+     frame. */
+  int32_t last_proc_stream_id;
   /* Counter of unique ID of PING. Wraps when it exceeds
      NGHTTP2_MAX_UNIQUE_ID */
   uint32_t next_unique_id;
@@ -156,7 +161,7 @@ struct nghttp2_session {
   /* Flags indicating GOAWAY is sent and/or recieved. The flags are
      composed by bitwise OR-ing nghttp2_goaway_flag. */
   uint8_t goaway_flags;
-  /* This is the value in GOAWAY frame sent by remote endpoint. */
+  /* This is the value in GOAWAY frame received from remote endpoint. */
   int32_t last_stream_id;
 
   /* Non-zero indicates connection-level flow control on remote side

lib/nghttp2_submit.c

@@ -202,7 +202,7 @@ int nghttp2_submit_goaway(nghttp2_session *session, uint8_t flags,
                           nghttp2_error_code error_code,
                           uint8_t *opaque_data, size_t opaque_data_len)
 {
-  return nghttp2_session_add_goaway(session, session->last_recv_stream_id,
+  return nghttp2_session_add_goaway(session, session->last_stream_id,
                                     error_code, opaque_data, opaque_data_len);
 }