[nginx] HTTP/2: don't send WINDOW_UPDATE for an empty request body.

[Valentin Bartenev]

details:   http://hg.nginx.org/nginx/rev/7760b54d5458
branches:  
changeset: 6518:7760b54d5458
user:      Valentin Bartenev <vbart at nginx.com>
date:      Tue Apr 19 17:38:49 2016 +0300
description:
HTTP/2: don't send WINDOW_UPDATE for an empty request body.

Particularly this prevents sending WINDOW_UPDATE with zero delta
which can result in PROTOCOL_ERROR.

Also removed surplus setting of no_flow_control to 0.

diffstat:

 src/http/v2/ngx_http_v2.c |  29 +++++++++++++++--------------
 1 files changed, 15 insertions(+), 14 deletions(-)

diffs (39 lines):

diff -r 657e029bac28 -r 7760b54d5458 src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c	Tue Apr 19 17:18:28 2016 +0300
+++ b/src/http/v2/ngx_http_v2.c	Tue Apr 19 17:38:49 2016 +0300
@@ -3481,20 +3481,21 @@ ngx_http_v2_read_request_body(ngx_http_r
         return ngx_http_v2_process_request_body(r, NULL, 0, 1);
     }
 
-    if (r->request_body_no_buffering) {
-        stream->no_flow_control = 0;
-        stream->recv_window = (size_t) len;
-
-    } else {
-        stream->no_flow_control = 1;
-        stream->recv_window = NGX_HTTP_V2_MAX_WINDOW;
-    }
-
-    if (ngx_http_v2_send_window_update(stream->connection, stream->node->id,
-                                       stream->recv_window)
-        == NGX_ERROR)
-    {
-        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    if (len) {
+        if (r->request_body_no_buffering) {
+            stream->recv_window = (size_t) len;
+
+        } else {
+            stream->no_flow_control = 1;
+            stream->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+        }
+
+        if (ngx_http_v2_send_window_update(stream->connection, stream->node->id,
+                                           stream->recv_window)
+            == NGX_ERROR)
+        {
+            return NGX_HTTP_INTERNAL_SERVER_ERROR;
+        }
     }
 
     ngx_add_timer(r->connection->read, clcf->client_body_timeout);