Possible bug with -f test

Server NGINX
1

I’m seeing a problem with static file handling when using multiple -f
tests in a location block. I could be doing something stupid, but from
the debug log it looks like a bug is corrupting the pathname nginx uses
to serve the static file…

The corrupt filename should be “/tmp/home.html” but is in the debug log
as:

2010/06/10 13:12:22 [debug] 15629#0: *3 http filename: 
"/tmp/home.htmlTP/1.1
Host"

This is for nginx-0.7.66 compiled with: --with-http_realip_module
–with-debug

Config:

    server {
        listen       174.37.76.178:80;
                listen            10.16.10.202:80;
        #listen       208.101.17.12:80;
        server_name  _;

                set $path_a 
/var/www/otherpeoplespixels.com/sites/content;

                location ~ ^/(.+\.html)$ {
                        alias                   /tmp/$1;
                        expires                 1m;
                        log_not_found   off;
                        #error_page             404 = @catalyst;

                        set $is_down no;
                        if ( -f /tmp/$host/.down ) {
                                set $is_down yes;
                        }
                        if ( -f $path_a/$host/.grace_period ) {
                                set $is_down no;
                        }
                        if ( $is_down = yes ) {
                                return 503;
                        }
                }

    }

}

Debug log:

2010/06/10 13:12:22 [debug] 15629#0: *3 accept: 192.168.0.100 fd:3
2010/06/10 13:12:22 [debug] 15629#0: *3 event timer add: 3: 
60000:1276190002121
2010/06/10 13:12:22 [debug] 15629#0: *3 epoll add event: fd:3 op:1 
ev:80000001
2010/06/10 13:12:22 [debug] 15629#0: timer delta: 7268
2010/06/10 13:12:22 [debug] 15629#0: posted events 0000000000000000
2010/06/10 13:12:22 [debug] 15629#0: worker cycle
2010/06/10 13:12:22 [debug] 15629#0: epoll timer: 60000
2010/06/10 13:12:22 [debug] 15629#0: epoll: fd:3 ev:0001 
d:00007F476446C220
2010/06/10 13:12:22 [debug] 15629#0: *3 malloc: 00000000006A9FB0:1256
2010/06/10 13:12:22 [debug] 15629#0: *3 malloc: 000000000068DE30:256
2010/06/10 13:12:22 [debug] 15629#0: *3 malloc: 000000000069B180:1024
2010/06/10 13:12:22 [debug] 15629#0: *3 malloc: 000000000069B590:4096
2010/06/10 13:12:22 [debug] 15629#0: *3 http process request line
2010/06/10 13:12:22 [debug] 15629#0: *3 recv: fd:3 82 of 1024
2010/06/10 13:12:22 [debug] 15629#0: *3 http request line: "GET 
/home.html HTTP/1.1"
2010/06/10 13:12:22 [debug] 15629#0: *3 http uri: "/home.html"
2010/06/10 13:12:22 [debug] 15629#0: *3 http args: ""
2010/06/10 13:12:22 [debug] 15629#0: *3 http exten: "html"
2010/06/10 13:12:22 [debug] 15629#0: *3 http process request header line
2010/06/10 13:12:22 [debug] 15629#0: *3 http header: "Host: 
XXXXXXXXXXXXXXXX.com"
2010/06/10 13:12:22 [debug] 15629#0: *3 http header: "Connection: close"
2010/06/10 13:12:22 [debug] 15629#0: *3 http header done
2010/06/10 13:12:22 [debug] 15629#0: *3 event timer del: 3: 
1276190002121
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 0
2010/06/10 13:12:22 [debug] 15629#0: *3 add cleanup: 000000000069BF50
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 1
2010/06/10 13:12:22 [debug] 15629#0: *3 http script value: 
"/usr/local/application/catalyst/root/sites"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script set $path_a
2010/06/10 13:12:22 [debug] 15629#0: *3 test location: ~ "^/(.+\.html)$"
2010/06/10 13:12:22 [debug] 15629#0: *3 using configuration 
"^/(.+\.html)$"
2010/06/10 13:12:22 [debug] 15629#0: *3 http cl:-1 max:1048576
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 3
2010/06/10 13:12:22 [debug] 15629#0: *3 http script value: "no"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script set $is_down
2010/06/10 13:12:22 [debug] 15629#0: *3 http script complex value
2010/06/10 13:12:22 [debug] 15629#0: *3 http script copy: "/tmp/"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script var: 
"XXXXXXXXXXXXXXXX.com"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script copy: "/.down"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script file op 
0000000000000000 "/tmp/XXXXXXXXXXXXXXXX.com/.down"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script file op false
2010/06/10 13:12:22 [debug] 15629#0: *3 http script if
2010/06/10 13:12:22 [debug] 15629#0: *3 http script if: false
2010/06/10 13:12:22 [debug] 15629#0: *3 http script complex value
2010/06/10 13:12:22 [debug] 15629#0: *3 http script var: 
"/usr/local/application/catalyst/root/sites"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script copy: "/"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script var: 
"XXXXXXXXXXXXXXXX.com"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script copy: 
"/.grace_period"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script file op 
0000000000000000 
"/usr/local/application/catalyst/root/sites/XXXXXXXXXXXXXXXX.com/.grace_period"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script if
2010/06/10 13:12:22 [debug] 15629#0: *3 http script value: "no"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script set $is_down
2010/06/10 13:12:22 [debug] 15629#0: *3 http script var
2010/06/10 13:12:22 [debug] 15629#0: *3 http script var: "no"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script value: "yes"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script equal
2010/06/10 13:12:22 [debug] 15629#0: *3 http script equal: no
2010/06/10 13:12:22 [debug] 15629#0: *3 http script if
2010/06/10 13:12:22 [debug] 15629#0: *3 http script if: false
2010/06/10 13:12:22 [debug] 15629#0: *3 post rewrite phase: 4
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 5
2010/06/10 13:12:22 [debug] 15629#0: *3 add cleanup: 000000000069C270
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 6
2010/06/10 13:12:22 [debug] 15629#0: *3 generic phase: 7
2010/06/10 13:12:22 [debug] 15629#0: *3 access phase: 8
2010/06/10 13:12:22 [debug] 15629#0: *3 access phase: 9
2010/06/10 13:12:22 [debug] 15629#0: *3 post access phase: 10
2010/06/10 13:12:22 [debug] 15629#0: *3 content phase: 11
2010/06/10 13:12:22 [debug] 15629#0: *3 content phase: 12
2010/06/10 13:12:22 [debug] 15629#0: *3 content phase: 13
2010/06/10 13:12:22 [debug] 15629#0: *3 http script copy: "/tmp/"
2010/06/10 13:12:22 [debug] 15629#0: *3 http script capture: "home.html"
2010/06/10 13:12:22 [debug] 15629#0: *3 http filename: 
"/tmp/home.htmlTP/1.1
Host"
2010/06/10 13:12:22 [debug] 15629#0: *3 add cleanup: 000000000069C2B8
2010/06/10 13:12:22 [debug] 15629#0: *3 http finalize request: 404, 
"/home.html?" 1
2010/06/10 13:12:22 [debug] 15629#0: *3 http special response: 404, 
"/home.html?"
2010/06/10 13:12:22 [debug] 15629#0: *3 http set discard body
2010/06/10 13:12:22 [debug] 15629#0: *3 HTTP/1.1 404 Not Found
Server: nginx/0.7.66
Date: Thu, 10 Jun 2010 17:12:22 GMT
Content-Type: text/html
Content-Length: 169
Connection: close

2010/06/10 13:12:22 [debug] 15629#0: *3 write new buf t:1 f:0 
000000000069C338, pos 000000000069C338, size: 150 file: 0, size: 0
2010/06/10 13:12:22 [debug] 15629#0: *3 http write filter: l:0 f:0 s:150
2010/06/10 13:12:22 [debug] 15629#0: *3 http output filter "/home.html?"
2010/06/10 13:12:22 [debug] 15629#0: *3 copy filter: "/home.html?"
2010/06/10 13:12:22 [debug] 15629#0: *3 http postpone filter 
"/home.html?" 000000000069C4F0
2010/06/10 13:12:22 [debug] 15629#0: *3 write old buf t:1 f:0 
000000000069C338, pos 000000000069C338, size: 150 file: 0, size: 0
2010/06/10 13:12:22 [debug] 15629#0: *3 write new buf t:0 f:0 
0000000000000000, pos 0000000000675D40, size: 116 file: 0, size: 0
2010/06/10 13:12:22 [debug] 15629#0: *3 write new buf t:0 f:0 
0000000000000000, pos 00000000006757C0, size: 53 file: 0, size: 0
2010/06/10 13:12:22 [debug] 15629#0: *3 http write filter: l:1 f:0 s:319
2010/06/10 13:12:22 [debug] 15629#0: *3 http write filter limit 0
2010/06/10 13:12:22 [debug] 15629#0: *3 writev: 319
2010/06/10 13:12:22 [debug] 15629#0: *3 http write filter 
0000000000000000
2010/06/10 13:12:22 [debug] 15629#0: *3 copy filter: 0 "/home.html?"
2010/06/10 13:12:22 [debug] 15629#0: *3 http finalize request: 0, 
"/home.html?" 1
2010/06/10 13:12:22 [debug] 15629#0: *3 http close request
2010/06/10 13:12:22 [debug] 15629#0: *3 http log handler
2010/06/10 13:12:22 [debug] 15629#0: *3 malloc: 0000000000692000:4096
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 000000000069B590, unused: 
96
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 0000000000692000, unused: 
3954
2010/06/10 13:12:22 [debug] 15629#0: *3 close http connection: 3
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 000000000069B180
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 00000000006A9FB0
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 000000000068DB50, unused: 
8
2010/06/10 13:12:22 [debug] 15629#0: *3 free: 000000000068DE30, unused: 
128
2010/06/10 13:12:22 [debug] 15629#0: timer delta: 0
2010/06/10 13:12:22 [debug] 15629#0: posted events 0000000000000000
2010/06/10 13:12:22 [debug] 15629#0: worker cycle
2010/06/10 13:12:22 [debug] 15629#0: epoll timer: -1

This occurs for all possible combinations of true/false results for the
two -f tests.
The existence of /tmp/$host/.down has no effect.
BUT, if the directory $path_a/$host does NOT exist, this corruption does
NOT happen.

I am happy to try permutations of this config and or request as needed
to help track down the cause.

Best,
Brian

Posted at Nginx Forum:

2

On Thu, Jun 10, 2010 at 01:56:19PM -0400, bkirkbri wrote:

Config:
alias /tmp/$1;
}
if ( $is_down = yes ) {
return 503;
}
}

}

}
[/code]

The bug is in “alias/if” combination. “root” should work:

      location ~ \.html$ {
            root      /tmp;
            ...

–
Igor S.
http://sysoev.ru/en/

3

Igor S. Wrote:

Igor Sysoev

Cool, it does work with “root” instead of “alias”. I had tried that,
but wasn’t sure if it was a safe alternative because of the warning from
Dave C. on this page:

Posted at Nginx Forum:

4

On Thu, Jun 10, 2010 at 02:55:26PM -0400, bkirkbri wrote:

–
Igor S.
Igor Sysoev

Cool, it does work with “root” instead of “alias”. I had tried that, but wasn’t sure if it was a safe alternative because of the warning from Dave C. on this page:

Setting the "Expires" HTTP header for static content served from Nginx? - Server Fault

“root” is good and safe directive. It works with all these "if"s.

“alias” is more generic than “root”: you can always describe “root”
mapping
via “alias”:

location /dir/ {
root /path/to;
}

is the same as

location /dir/ {
alias /path/to/dir/;
}

But not opposite, for example, you can not describe this

location /dir1/ {
alias /path/to/dir2/;
}

using “root”. I use “root” always if it’s possible.

–
Igor S.
http://sysoev.ru/en/

5

Igor S. Wrote:

   alias /path/to/dir2/;

}

using “root”. I use “root” always if it’s
possible.

–
Igor S.
Igor Sysoev

Excellent, thank you for the help.

Posted at Nginx Forum: