Upstream: avoid closing client connection in edge case.
If proxy_cache is enabled, and proxy_no_cache 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.
Example configuration:
proxy_cache foo;
proxy_cache_bypass 1;
proxy_no_cache 1;
If a client sends If-None-Match, and the upstream server returns 200 with a
matching ETag, no body should be returned to the client. At the start of
ngx_http_upstream_send_response proxy_no_cache is not yet tested, thus cacheable
is still 1 and downstream_error is set.
However, by the time the downstream_error check is done in process_request,
proxy_no_cache has been tested and cacheable is set to 0. The client connection
is then closed, regardless of keepalive.
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 08fa95a..3d01523 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2861,6 +2861,11 @@
ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
}
+ if (r->header_only && !u->cacheable && !u->store) {
+ ngx_http_upstream_finalize_request(r, u, 0);
+ return;
+ }
+
#endif
p = u->pipe;
