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Posted to dev@apr.apache.org by Ivan Prostran <iv...@bulb.hr> on 2012/09/21 12:41:44 UTC

Input filters that alter content-length

Hi,

I have the following scenario :

- Apache/2.2.19 (Solaris 10 SPARC)

      SetInputFilter alterxmlbody (AP_FTYPE_RESOURCE)
      SetHandler weblogic-handler


The handler forwards requests to multiple weblogic servers
and the filter itself analyzes and/or changes the POST data
in a way that the length of the incoming request may be changed.

The question is :

What is the proper and legitimate way to deal with this situation?

Should the input filter set the new CL value in "headers_in" before
returning from the callback, or just remove it from the list?

apr_off_t length;
apr_brigade_length     (bb,1,&length);
apr_table_setn(f->r->headers_in, "Content-Length", 
apr_off_t_toa(f->r->pool, length));

or

apr_table_unset(f->r->headers_in, "Content-Length");


Best regards
Ivan

Re: Input filters that alter content-length

Posted by Ivan Prostran <iv...@bulb.hr>.
Hi,

Thanks for your prompt response.

Regards,
Ivan

On 09/21/12 13:05, Graham Leggett wrote:
> On 21 Sep 2012, at 12:41 PM, Ivan Prostran <iv...@bulb.hr> wrote:
>
>> I have the following scenario :
>>
>> - Apache/2.2.19 (Solaris 10 SPARC)
>>
>>      SetInputFilter alterxmlbody (AP_FTYPE_RESOURCE)
>>      SetHandler weblogic-handler
> First off, the users@httpd.apache.org list is a better place for this, this is the APR list.
>
>> The handler forwards requests to multiple weblogic servers
>> and the filter itself analyzes and/or changes the POST data
>> in a way that the length of the incoming request may be changed.
>>
>> The question is :
>>
>> What is the proper and legitimate way to deal with this situation?
>>
>> Should the input filter set the new CL value in "headers_in" before
>> returning from the callback, or just remove it from the list?
>>
>> apr_off_t length;
>> apr_brigade_length     (bb,1,&length);
>> apr_table_setn(f->r->headers_in, "Content-Length", apr_off_t_toa(f->r->pool, length));
> This is definitely wrong - a filter can expect to be called multiple times, the above code assumes you'll be called once.
>
>> or
>>
>> apr_table_unset(f->r->headers_in, "Content-Length");
> This is the simplest way to do it, a further filter inside httpd will put Content-Length back if practical.
>
> Look in the httpd source for examples on how filters handle this kind of thing.
>
> Regards,
> Graham
> --
>

Re: Input filters that alter content-length

Posted by Graham Leggett <mi...@sharp.fm>.
On 21 Sep 2012, at 12:41 PM, Ivan Prostran <iv...@bulb.hr> wrote:

> I have the following scenario :
> 
> - Apache/2.2.19 (Solaris 10 SPARC)
> 
>     SetInputFilter alterxmlbody (AP_FTYPE_RESOURCE)
>     SetHandler weblogic-handler

First off, the users@httpd.apache.org list is a better place for this, this is the APR list.

> The handler forwards requests to multiple weblogic servers
> and the filter itself analyzes and/or changes the POST data
> in a way that the length of the incoming request may be changed.
> 
> The question is :
> 
> What is the proper and legitimate way to deal with this situation?
> 
> Should the input filter set the new CL value in "headers_in" before
> returning from the callback, or just remove it from the list?
> 
> apr_off_t length;
> apr_brigade_length     (bb,1,&length);
> apr_table_setn(f->r->headers_in, "Content-Length", apr_off_t_toa(f->r->pool, length));

This is definitely wrong - a filter can expect to be called multiple times, the above code assumes you'll be called once.

> or
> 
> apr_table_unset(f->r->headers_in, "Content-Length");

This is the simplest way to do it, a further filter inside httpd will put Content-Length back if practical.

Look in the httpd source for examples on how filters handle this kind of thing.

Regards,
Graham
--