passing data to CGI scripts via PATH_INFO

[Valentin V. Bartenev]

On Thursday 22 May 2014 22:14:23 Lyle wrote:
> On 22/05/2014 19:32, Valentin V. Bartenev wrote:
> > On Thursday 22 May 2014 16:26:54 Phil Knight wrote:
> >> Hi
> >>
> >> We are having an issue passing data to CGI scripts via PATH_INFO
> >> environment variable.
> >>
> >> for example:-
> >>
> >> http://domain.com/cgi-bin/script.cgi/=
> >>
> >> On  various apache servers this works fine and the PATH_INFO variable
> >> will contain "/=", on our nginx server we are getting a 403 forbidden
> >> error. We are using fcgiwrap [1] for running CGI and .cgi scripts are
> >> executing.
> >>
> >> Could this be an issue with nginx configuration?
> > [..]
> >
> > Most likely this is an issue with the configuration.
> 
> I think the relevant part is here:
> 
> location /cgi-bin/ {
>              root                /users/folder;
>              gzip                off;
>              fastcgi_pass        unix:/var/run/fcgiwrap.socket;
>              fastcgi_param  QUERY_STRING       $query_string;
>              fastcgi_param  REQUEST_METHOD     $request_method;
>              fastcgi_param  CONTENT_TYPE       $content_type;
>              fastcgi_param  CONTENT_LENGTH     $content_length;
>              fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
>              fastcgi_param  PATH_INFO         $fastcgi_path_info;
>              fastcgi_param  REQUEST_URI        $request_uri;
>              fastcgi_param  DOCUMENT_URI       $document_uri;
>              fastcgi_param  SERVER_PROTOCOL    $server_protocol;
>              fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
>              fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;
>              fastcgi_param  REMOTE_ADDR        $remote_addr;
>              fastcgi_param  REMOTE_PORT        $remote_port;
>              fastcgi_param  SERVER_ADDR        $server_addr;
>              fastcgi_param  SERVER_PORT        $server_port;
>              fastcgi_param  SERVER_NAME        $server_name;
> 
>              fastcgi_param       DOCUMENT_ROOT /users/folder/cgi-bin/;
>              fastcgi_param       SCRIPT_FILENAME 
> $document_root$fastcgi_script_name;
>              fastcgi_connect_timeout 120;
>              fastcgi_send_timeout    120;
>              fastcgi_read_timeout    120;
>          }
> 
> I could be wrong. Any pointers would be very much appreciated.
> 
> I've noticed that:
> 
> http://domain.com/cgi-bin/no_existent_script.cgi
> 
> Also gives a 403. So I suspect that nginx is looking for a file called = 
> in a folder named api.cgi/
> I'm not sure what configuration we need to do to fix this.
[..]

As I already said, nginx knows nothing about CGI.  It doesn't look for any 
files in your location with "fastcgi_pass".  It just passes request and
all the FastCGI params that you have configured with the values that you
have set.

For example, since you have:

  fastcgi_param  PATH_INFO $fastcgi_path_info;

and missing the fastcgi_split_path_info directive, then probably nginx pases 
empty string in PATH_INFO.

Please, check the docs to figure out how exactly the $fastcgi_path_info 
variable works and what values it takes:
http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#var_fastcgi_path_info

The whole list of variables with links to descriptions can be found here:
http://nginx.org/en/docs/varindex.html

Then, probably, you need to check fcgiwrap documentation to figure out what 
variables it expects and how they are processed.

  wbr, Valentin V. Bartenev