nginx serving wrong website under proxy_cache

[Igor Sysoev]

On Sun, May 03, 2009 at 03:15:33AM -0400, Jim Ohlstein wrote:

> 
> 
> Igor Sysoev wrote:
> >On Sun, May 03, 2009 at 02:05:57AM -0400, Jim Ohlstein wrote:
> >
> >  
> >>Igor Sysoev wrote:
> >>    
> >>>On Sun, May 03, 2009 at 01:18:30AM -0400, Jim Ohlstein wrote:
> >>>
> >>> 
> >>>      
> >>>>Igor Sysoev wrote:
> >>>>   
> >>>>        
> >>>>>On Sat, May 02, 2009 at 11:16:47PM -0400, Jim Ohlstein wrote:
> >>>>>
> >>>>>
> >>>>>     
> >>>>>          
> >>>>>>Correction:
> >>>>>>
> >>>>>>The question should read:
> >>>>>>
> >>>>>>Do I need to use two fastcgi_cache_key settings if a site serves both 
> >>>>>>http and https?
> >>>>>>  
> >>>>>>       
> >>>>>>            
> >>>>>If you use the same backend - no:
> >>>>>
> >>>>>    server {
> >>>>>        listen 80;
> >>>>>        location / {
> >>>>>            fastcgi_pass       backend:9000;
> >>>>>            fastcgi_cache_key  backend:9000$request_uri;
> >>>>>        }
> >>>>>    }
> >>>>>
> >>>>>    server {
> >>>>>        listen 443;
> >>>>>        location / {
> >>>>>            fastcgi_pass       backend:9000;
> >>>>>            fastcgi_cache_key  backend:9000$request_uri;
> >>>>>        }
> >>>>>    }
> >>>>>
> >>>>>
> >>>>>     
> >>>>>          
> >>>>I am using the same backend and configured like this:
> >>>>
> >>>>server {
> >>>>  listen  80;
> >>>>
> >>>>  location / {
> >>>>      fastcgi_pass backend;
> >>>>      fastcgi_cache one;
> >>>>      fastcgi_cache_key backend$request_uri;
> >>>>  }
> >>>>}
> >>>>
> >>>>server {
> >>>>  listen     443;
> >>>>  location / {
> >>>>      fastcgi_pass backend;
> >>>>      fastcgi_cache one;
> >>>>      fastcgi_cache_key backend$request_uri;
> >>>>  }
> >>>>}
> >>>>   
> >>>>        
> >>>Yes, this is OK.
> >>>
> >>> 
> >>>      
> >>>>For what it may be worth, I have seen some md5 collisions in the error 
> >>>>log:
> >>>>
> >>>>2009/05/03 00:39:18 [crit] 21997#0: *61 cache file 
> >>>>"/usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0" has md5 
> >>>>collision, client: my.ip.addr.ess, server: mydomain.com, request: "GET 
> >>>>/rtwhtrsyrn/010110A/687474702s7777772r777732746s7073697465732r636s6q2s627574746s6r2r7068703s753q776s726p6477617274776s7n6s6r655s636s6q 
> >>>>HTTP/1.1", host: "mydomain.com", referrer: 
> >>>>"https://mydomain.com/rtwhtrsyrn/010110A/687474702s776s726p6477617274776s7n6s6r652r636s6q2s666s72756q732s616r6r6s756r63656q656r74732s31333535392q6r6s2q796s752q6172656r742q6372617n792r68746q6p"
> >>>>2009/05/03 00:39:24 [crit] 21997#0: *44 cache file 
> >>>>"/usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0" has md5 
> >>>>collision, client: my.ip.addr.ess, server: mydomain.com, request: "GET 
> >>>>/rtwhtrsyrn/010110A/687474702s7777772r777732746s7073697465732r636s6q2s627574746s6r2r7068703s753q776s726p6477617274776s7n6s6r655s636s6q 
> >>>>HTTP/1.1", host: "mydomain.com", referrer: 
> >>>>"https://mydomain.com/rtwhtrsyrn/010110A/687474702s776s726p6477617274776s7n6s6r652r636s6q2s666s72756q732s2r2r2s"
> >>>>   
> >>>>        
> >>>nginx uses md5 create a cache key and use the key as path to a cache 
> >>>file,
> >>>90e8de013d4126fbab247d12350fdda0 in you case. Besides, in the file there
> >>>is crc32 of the original key to test possible md5 collisions.
> >>>
> >>>Could you run
> >>>
> >>>head -1 /usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0 | 
> >>>hexdump
> >>>head -2 /usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0 | 
> >>>tail -1
> >>>
> >>>?
> >>>
> >>>
> >>> 
> >>>      
> >>[root at saturn logs]# head -1 
> >>/usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0 | hexdump
> >>0000000 8ab0 1afc 0000 0000 1a20 b835 0032 0000
> >>0000010 0000 0000 0000 0000 0000 0000 0000 0000
> >>0000020 028b 0000 0000 0000 000a              
> >>0000029
> >>[root at saturn logs]# head -2 
> >>/usr/local/nginx/cache/0/da/90e8de013d4126fbab247d12350fdda0 | tail -1
> >>KEY: 
> >>unix:/tmp/cgi.sock.1:/rtwhtrsyrn/010110A/687474702s7777772r777732746s7073697465732r636s6q2s627574746s6r2r7068703s753q776s726p6477617274776s7n6s6r655s636s6q
> >>    
> >
> >It's seems like nginx bug. Could you create debug log ?
> >
> >
> >  
> I'm sure I could... if only I knew how. :)
> 
> Can you please give me the steps you want me to take?
> It will have to wait a few hours. It's ~ 0315 here and I'm going to bed.

./configure --with-debug ...

nginx.conf:

error_log /path/to/log  debug;

or, if you can easy reproduce the bug with single request:

events {
     debug_connection  your.ip.address;
}


-- 
Igor Sysoev
http://sysoev.ru/en/