From 6da044cbb51d33c68c66c2f74eb6059b1f1c1b74 Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Wed, 2 Jul 2014 21:20:40 +0900
Subject: [PATCH] Send WINDOW_UPDATE for ignored DATA bytes when manual flow
 control is enabled

Since we do not call on_data_chunk_recv_callback for ignored DATA
chunk, if nghttp2_option_set_no_auto_connection_window_update is used,
application may not have a chance to send connection WINDOW_UPDATE.
To fix this, we accumulate those received bytes, and if it exceeds
certain number, we automatically send connection-level WINDOW_UPDATE.
---
 lib/nghttp2_session.c | 22 ++++++++++++++++++++++
 lib/nghttp2_session.h |  9 +++++++++
 lib/nghttp2_submit.c  |  6 ++++++
 3 files changed, 37 insertions(+)

diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index 014fcd6b..9ae6cff1 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -3889,6 +3889,10 @@ static int session_update_recv_connection_window_size
                                             session->recv_window_size);
       if(rv == 0) {
         session->recv_window_size = 0;
+        /* recv_ign_window_size keeps track of ignored DATA bytes
+           before any connection-level WINDOW_UPDATE therefore, we can
+           reset it here. */
+        session->recv_ign_window_size = 0;
       } else {
         return rv;
       }
@@ -5027,12 +5031,30 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
                      readlen, iframe->payloadleft));
 
       if(readlen > 0) {
+        session->recv_ign_window_size += readlen;
+
         /* Update connection-level flow control window for ignored
            DATA frame too */
         rv = session_update_recv_connection_window_size(session, readlen);
         if(nghttp2_is_fatal(rv)) {
           return rv;
         }
+
+        if((session->opt_flags &
+            NGHTTP2_OPTMASK_NO_AUTO_CONNECTION_WINDOW_UPDATE) &&
+           nghttp2_should_send_window_update
+           (session->local_window_size, session->recv_ign_window_size)) {
+
+          rv = nghttp2_session_add_window_update
+            (session, NGHTTP2_FLAG_NONE, 0, session->recv_ign_window_size);
+
+          if(nghttp2_is_fatal(rv)) {
+            return rv;
+          }
+
+          session->recv_window_size -= session->recv_ign_window_size;
+          session->recv_ign_window_size = 0;
+        }
       }
 
       if(iframe->payloadleft) {
diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h
index 871fca6f..0cf28ffc 100644
--- a/lib/nghttp2_session.h
+++ b/lib/nghttp2_session.h
@@ -200,6 +200,15 @@ struct nghttp2_session {
      WINDOW_UPDATE. This could be negative after submitting negative
      value to WINDOW_UPDATE. */
   int32_t recv_window_size;
+  /* The number of bytes in ignored DATA frame received without
+     connection-level WINDOW_UPDATE.  Since we do not call
+     on_data_chunk_recv_callback for ignored DATA chunk, if
+     nghttp2_option_set_no_auto_connection_window_update is used,
+     application may not have a chance to send connection
+     WINDOW_UPDATE.  To fix this, we accumulate those received bytes,
+     and if it exceeds certain number, we automatically send
+     connection-level WINDOW_UPDATE. */
+  int32_t recv_ign_window_size;
   /* The amount of recv_window_size cut using submitting negative
      value to WINDOW_UPDATE */
   int32_t recv_reduction;
diff --git a/lib/nghttp2_submit.c b/lib/nghttp2_submit.c
index 748d47d6..48a4b876 100644
--- a/lib/nghttp2_submit.c
+++ b/lib/nghttp2_submit.c
@@ -348,6 +348,11 @@ int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
     if(rv != 0) {
       return rv;
     }
+
+    /* recv_ign_window_size keeps track of ignored DATA bytes before
+       any connection-level WINDOW_UPDATE therefore, we can reset it
+       here. */
+    session->recv_ign_window_size = 0;
   } else {
     stream = nghttp2_session_get_stream(session, stream_id);
     if(stream) {
@@ -362,6 +367,7 @@ int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
       return 0;
     }
   }
+
   if(window_size_increment > 0) {
     return nghttp2_session_add_window_update(session, flags, stream_id,
                                              window_size_increment);