[PATCH] Upstream: avoid closing client conn when no response body needed

[Justin Li]

# HG changeset patch
# User Justin Li <jli.justinli at gmail.com>
# Date 1457490530 18000
#      Tue Mar 08 21:28:50 2016 -0500
# Node ID e9f916f271b86e446c6f1de371832432a9f2a66d
# Parent  c5f81dcf97a79576138917501c9a6cc6f53ee930
Upstream: avoid closing client conn when no response body needed

If proxy_cache is enabled, and proxy_cache_bypass tests true, it was previously
possible for the client connection to be closed after a 304. The fix is to
recheck r->header_only after the final cacheability is determined, and end the
request if no longer cacheable.

diff -r c5f81dcf97a7 -r e9f916f271b8 src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c	Thu Mar 03 21:14:19 2016 +0300
+++ b/src/http/ngx_http_upstream.c	Tue Mar 08 21:28:50 2016 -0500
@@ -2861,6 +2861,12 @@ ngx_http_upstream_send_response(ngx_http
         ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
     }
 
+    if (r->header_only && !u->cacheable && !u->store) {
+        u->pipe->downstream_error = 0;
+        ngx_http_upstream_finalize_request(r, u, rc);
+        return;
+    }
+
 #endif
 
     p = u->pipe;