On Tue, Jul 24, 2012 at 12:28 AM, Glen Birnie <glen.bir...@bbc.co.uk> wrote:
> We have seen an issue in httpd 2.2.21 where mod_cache incorrectly returns > HTTP 200 responses instead of HTTP 404 where: > > - Reverse proxying is configured. > - ProxyErrorOverride is set to On. > - mod_disk_cache is set up to cache content proxied from mod_proxy. > - A local ErrorDocument 404 URL is configured. > - The error document URL is requested and the contents cached by > mod_disk_cache. > - A nonexistent URL is routed to the proxy destination, the destination > proxy returns a 404, but mod_cache returns the configured ErrorDocument > content with an incorrect 200 response. > > We have done some searching of the list archives and bug database but have > not seen reports of any similar problems. > > --- > > Steps to reproduce: > > - Create an error image and write to the document root (we assume URI > /error.jpg in the examples below). > > - Setup a mod_disk_cache directory (we assume > /data/httpcache/httpd/cache-root) with the necessary permissions. > > - Use configuration akin to the following (set "proxy.destination" / > "web.proxy" as appropriate): > > <IfModule !mod_cache.c> > LoadModule cache_module modules/mod_cache.so > </IfModule> > > <IfModule !mod_disk_cache.c> > LoadModule disk_cache_module modules/mod_disk_cache.so > </IfModule> > > <IfModule !mod_rewrite.c> > LoadModule rewrite_module modules/mod_rewrite.so > </IfModule> > > <IfModule !mod_proxy.c> > LoadModule proxy_module modules/mod_proxy.so > </IfModule> > > <IfModule mod_cache.c> > <IfModule mod_disk_cache.c> > CacheRoot /data/httpcache/httpd/cache-root > CacheDirLevels 3 > CacheDirLength 1 > CacheMinFileSize 0 > CacheMaxFileSize 1000000 > </IfModule> > </IfModule> > > CacheEnable disk / > > ProxyErrorOverride On > ProxyPassReverse / http://proxy.destination/ > > # Configure this if the destination server resides behind a proxy > #ProxyRemote http://proxy.destination/ http://web.proxy:80 > > <Location /proxystuff/> > RewriteEngine On > RewriteRule /proxystuff/error$ /error.jpg [L] > RewriteRule /proxystuff/get http://proxy.destination%{REQUEST_URI} [P,L] > > # This image should reside in the document root, > # i.e. return a HTTP 200 when requested > ErrorDocument 404 /error.jpg > </Location> > > > - Request the error image e.g.: > > curl -Lsv -H 'Pragma: ' -o /dev/null http://localhost/error.jpg > > This should get written into the cache: > > htcacheclean -a -D -p /data/httpcache/httpd/cache-root > > > - Request a nonexistent proxied URL e.g.: > > curl -Lsv -H 'Pragma: ' -o /dev/null http://localhost/proxystuff/get > > An incorrect HTTP 200 response is returned instead of the expected HTTP > 404. > Note this does not happen if the CacheEnable directive is disabled. > > It appears that mod_cache is returning a cached 404 errordocument response > and assuming that (because this exists) a 200 should be issued, rather than > forwarding the 404 response from the destination proxy server. > > > Glen > > > http://www.bbc.co.uk/ > This e-mail (and any attachments) is confidential and may contain personal > views which are not the views of the BBC unless specifically stated. > If you have received it in error, please delete it from your system. > Do not use, copy or disclose the information in any way nor act in > reliance on it and notify the sender immediately. > Please note that the BBC monitors e-mails sent or received. > Further communication will signify your consent to this. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@httpd.apache.org > For additional commands, e-mail: users-h...@httpd.apache.org > > Use CacheDisable directive to disable caching for your custom error pages, something like this: CacheDisable /your_custom_err_pages and put 404 page inside Also according to the documentation you can use the no-cache environment variable to disable caching on finer grained set of resources. Igor
