[PATCH] Upstream: fixed $upstream_response_time for filter_finalize + error_page.

[Yichun Zhang (agentzh)]

Hello!

Please review the following patch.

Thanks!
-agentzh

# HG changeset patch
# User Yichun Zhang <agentzh at gmail.com>
# Date 1423789183 28800
#      Thu Feb 12 16:59:43 2015 -0800
# Node ID 8b3d7171f35e74c8bea3234e88d8977b4f11f815
# Parent  f3f25ad09deee27485050a75732e5f46ab1b18b3
Upstream: fixed $upstream_response_time for filter_finalize + error_page.

ngx_http_upstream_finalize_request() is always called twice when an
output filter module calls ngx_http_filter_finalize_request() *and*
a custom error page is configured by the error_page directive. This
is because

1. ngx_http_filter_finalize_request() triggers
        calling ngx_http_terminate_request
        => calling ngx_http_upstream_cleanup
        => calling ngx_http_upstream_finalize_request

2. ngx_http_internal_redirect() returns NGX_DONE
        ==> ngx_http_special_response_handler() returns NGX_DONE
        ==> ngx_http_filter_finalize_request() returns NGX_ERROR
        ==> ngx_http_send_header() returns NGX_ERROR
        ==> ngx_http_upstream_send_response() calls
            ngx_http_upstream_finalize_request() again in the same
            ngx_http_upstream_send_response() call as 1).

This might result in corrupted $upstream_response_time values (close
to the absolute timestamp value) when u->state->response_sec happens
to be non-zero.

This patch ensures that the $upstream_response_time value is only
calculated upon the first ngx_http_upstream_finalize_request()
invocation.

diff -r f3f25ad09dee -r 8b3d7171f35e src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c Wed Feb 11 20:18:55 2015 +0300
+++ b/src/http/ngx_http_upstream.c Thu Feb 12 16:59:43 2015 -0800
@@ -3738,7 +3738,7 @@ static void
 ngx_http_upstream_finalize_request(ngx_http_request_t *r,
     ngx_http_upstream_t *u, ngx_int_t rc)
 {
-    ngx_uint_t   flush;
+    ngx_uint_t   flush, cleaned;
     ngx_time_t  *tp;

     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
@@ -3747,6 +3747,10 @@ ngx_http_upstream_finalize_request(ngx_h
     if (u->cleanup) {
         *u->cleanup = NULL;
         u->cleanup = NULL;
+        cleaned = 0;
+
+    } else {
+        cleaned = 1;
     }

     if (u->resolved && u->resolved->ctx) {
@@ -3754,7 +3758,7 @@ ngx_http_upstream_finalize_request(ngx_h
         u->resolved->ctx = NULL;
     }

-    if (u->state && u->state->response_sec) {
+    if (!cleaned && u->state && u->state->response_sec) {
         tp = ngx_timeofday();
         u->state->response_sec = tp->sec - u->state->response_sec;
         u->state->response_msec = tp->msec - u->state->response_msec;
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