[nginx] Upstream: fixed u->conf->preserve_output (ticket #1519).

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/08f114ed5449
branches:  
changeset: 7260:08f114ed5449
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu Apr 05 16:56:12 2018 +0300
description:
Upstream: fixed u->conf->preserve_output (ticket #1519).

Previously, ngx_http_upstream_process_header() might be called after
we've finished reading response headers and switched to a different read
event handler, leading to errors with gRPC proxying.  Additionally,
the u->conf->read_timeout timer might be re-armed during reading response
headers (while this is expected to be a single timeout on reading
the whole response header).

diffstat:

 src/http/ngx_http_upstream.c |  20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)

diffs (37 lines):

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2013,8 +2013,6 @@ ngx_http_upstream_send_request(ngx_http_
 
     /* rc == NGX_OK */
 
-    u->request_body_sent = 1;
-
     if (c->write->timer_set) {
         ngx_del_timer(c->write);
     }
@@ -2041,11 +2039,19 @@ ngx_http_upstream_send_request(ngx_http_
         return;
     }
 
-    ngx_add_timer(c->read, u->conf->read_timeout);
-
-    if (c->read->ready) {
-        ngx_http_upstream_process_header(r, u);
-        return;
+    if (!u->request_body_sent) {
+        u->request_body_sent = 1;
+
+        if (u->header_sent) {
+            return;
+        }
+
+        ngx_add_timer(c->read, u->conf->read_timeout);
+
+        if (c->read->ready) {
+            ngx_http_upstream_process_header(r, u);
+            return;
+        }
     }
 }