Некорректная обработка директив конфига

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Если в конфиге несколько вирт. хостов, и хотя бы для одного из них включено кэширование (директивой proxy_cache), то при проксировании запросов заголовки, управляющие кэшированием (If-Modified-Since, If-None-Match), не передаются бэкэнду для других хостов (может быть, и локэйшн тоже) даже если те не должны кэшироваться nginx. Попытка ручной установки заголовков приводит к 404 ошибке.

Пример, на котором баг вопроизводится (опускаю не относящиеся к теме настройки):

http {
	proxy_set_header		Host				$host;
	proxy_set_header		X-Real-IP			$remote_addr;
	proxy_set_header		X-Forwarded-For 	$proxy_add_x_forwarded_for;
	proxy_cache_path		/opt/local/var/run/nginx/cache/images levels=1 keys_zone=images:1h max_size=1m;

	server {
		location / {
			proxy_pass		http://apache;
			proxy_cache 		images;
			proxy_cache_valid 	200 301 302 304 1h;
			proxy_hide_header 	"Set-Cookie";
			proxy_ignore_headers "Cache-Control" "Expires";
		}
	}
	server {
		location ~* \.jpg$ {
			proxy_pass		http://apache;
			#backend will never get if-modified-since headers
		}
	}
}

[Maxim Dounin]

Nice catch, thanks.

[Maxim Dounin]

Patch series which fixes this is available for review here:
​http://mailman.nginx.org/pipermail/nginx-devel/2011-November/001426.html

[Maxim Dounin]

In [4275/nginx]:

Fixed proxy_set_header inheritance with proxy_cache (ticket #45).

Headers cleared with cache enabled (If-Modified-Since etc.) might be cleared
in unrelated servers/locations without proxy_cache enabled if proxy_cache was
used in some server/location.

Example config which triggered the problem:

proxy_set_header X-Test "test";
server { location /1 { proxy_cache name; proxy_pass ... } }
server { location /2 { proxy_pass ... } }

Another one:

server {

proxy_cache name;
location /1 { proxy_pass ... }
location /2 { proxy_cache off; proxy_pass ... }

}

In both cases If-Modified-Since header wasn't sent to backend in location /2.

Fix is to not modify conf->headers_source, but instead merge user-supplied
headers from conf->headers_source and default headers (either cache or not)
into separate headers_merged array.

[Maxim Dounin]

Committed, thanks.

[Maxim Dounin]

In [4359/nginx]:

Merge of r4275, r4276, r4278, r4279:

Fixes for proxy_set_header, fastcgi/scgi/uwsgi_param inheritance:

*) Fixed proxy_set_header inheritance with proxy_cache (ticket #45).

Headers cleared with cache enabled (If-Modified-Since etc.) might be
cleared in unrelated servers/locations without proxy_cache enabled
if proxy_cache was used in some server/location.

Example config which triggered the problem:

proxy_set_header X-Test "test";
server { location /1 { proxy_cache name; proxy_pass ... } }
server { location /2 { proxy_pass ... } }

Another one:

server {

proxy_cache name;
location /1 { proxy_pass ... }
location /2 { proxy_cache off; proxy_pass ... }

}

In both cases If-Modified-Since header wasn't sent to backend in
location /2.

Fix is to not modify conf->headers_source, but instead merge user-supplied
headers from conf->headers_source and default headers (either cache or not)
into separate headers_merged array.

*) Fixed proxy_set_header inheritance with proxy_set_body.

*) Separate functions to merge fastcgi/scgi/uwsgi params.

No functional changes.

*) Fixed fastcgi/scgi/uwsgi_param inheritance. The following problems were

fixed:

1. Directive fastcgi_cache affected headers sent to backends in unrelated servers / locations (see ticket #45).

2. If-Unmodified-Since, If-Match and If-Range headers were sent to backends if fastcgi_cache was used.

3. Cache-related headers were sent to backends if there were no fastcgi_param directives and fastcgi_cache was used at server level.