details: http://hg.nginx.org/nginx/rev/5fb1e57c758a
branches:
changeset: 5735:5fb1e57c758a
user: Maxim Dounin <mdounin@mdounin.ru>
date: Thu Jun 26 02:27:11 2014 +0400
description:
Entity tags: explicit flag to skip not modified filter.

Previously, last_modified_time was tested against -1 to check if the
not modified filter should be skipped. Notably, this prevented nginx
from additional If-Modified-Since (et al.) checks on proxied responses.
Such behaviour is suboptimal in some cases though, as checks are always
skipped on responses from a cache with ETag only (without Last-Modified),
resulting in If-None-Match being ignored in such cases. Additionally,
it was not possible to return 412 from the If-Unmodified-Since if last
modification time was not known for some reason.

This change introduces explicit r->disable_not_modified flag instead,
which is set by ngx_http_upstream_process_headers().

diffstat:

src/http/modules/ngx_http_not_modified_filter_module.c | 10 +++++++++-
src/http/ngx_http_request.h | 1 +
src/http/ngx_http_upstream.c | 2 ++
3 files changed, 12 insertions(+), 1 deletions(-)

diffs (57 lines):

diff --git a/src/http/modules/ngx_http_not_modified_filter_module.c b/src/http/modules/ngx_http_not_modified_filter_module.c
--- a/src/http/modules/ngx_http_not_modified_filter_module.c
+++ b/src/http/modules/ngx_http_not_modified_filter_module.c
@@ -56,7 +56,7 @@ ngx_http_not_modified_header_filter(ngx_
{
if (r->headers_out.status != NGX_HTTP_OK
|| r != r->main
- || r->headers_out.last_modified_time == -1)
+ || r->disable_not_modified)
{
return ngx_http_next_header_filter(r);
}
@@ -114,6 +114,10 @@ ngx_http_test_if_unmodified(ngx_http_req
{
time_t iums;

+ if (r->headers_out.last_modified_time == (time_t) -1) {
+ return 0;
+ }
+
iums = ngx_http_parse_time(r->headers_in.if_unmodified_since->value.data,
r->headers_in.if_unmodified_since->value.len);

@@ -134,6 +138,10 @@ ngx_http_test_if_modified(ngx_http_reque
time_t ims;
ngx_http_core_loc_conf_t *clcf;

+ if (r->headers_out.last_modified_time == (time_t) -1) {
+ return 1;
+ }
+
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) {
diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -528,6 +528,7 @@ struct ngx_http_request_s {
unsigned filter_need_temporary:1;
unsigned allow_ranges:1;
unsigned single_range:1;
+ unsigned disable_not_modified:1;

#if (NGX_STAT_STUB)
unsigned stat_reading:1;
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
@@ -2238,6 +2238,8 @@ ngx_http_upstream_process_headers(ngx_ht

r->headers_out.content_length_n = u->headers_in.content_length_n;

+ r->disable_not_modified = !u->cacheable;
+
u->length = -1;

return NGX_OK;

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