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From <oh...@cox.net>
Subject Re: Confused about modules processing order...
Date Thu, 01 Jan 1970 00:00:00 GMT

---- ohaya@cox.net wrote: 
> 
> ---- Sorin Manolache <sorinm@gmail.com> wrote: 
> > On 2012-06-26 13:14, ohaya@cox.net wrote:
> > >
> > > ---- Sorin Manolache <sorinm@gmail.com> wrote:
> > >> On 2012-06-26 03:49, ohaya@cox.net wrote:
> > >>>
> > >>> Hi,
> > >>>
> > >>> I have my small prototype module, which I implemented starting with
the mod_headers.c source, working.  The changes that I did to the original source were to
add some code in the insert_filter hook to inject an additional header into the request.
> > >>>
> > >>> That seems to work ok with a "vanilla" Apache configuration.
> > >>>
> > >>> I want to be able to make my modified module work together with another
module, provided by Oracle (the Oracle Access Manager webgate, aka "webgate").
> > >>>
> > >>> However, after I add the directives into the Apache httpd.conf to enable
the webgate, it appears that, on incoming requests, the webgate processing occurs, but my
code in the modified mod_headers module is not called at all :(!!
> > >>>
> > >>>
> > >>> Here's the last part of my modified mod_headers.c:
> > >>>
> > >>> static void register_hooks(apr_pool_t *p)
> > >>> {
> > >>>       printf("mod_headers-jl V0.13 - use LIBCURL instead of OAM ASDK-process
response from callCurl\n");
> > >>>       printf("In register_hooks\n");
> > >>>       ap_register_output_filter("FIXUP_HEADERS_OUT", ap_headers_output_filter,
> > >>>                                 NULL, AP_FTYPE_CONTENT_SET);
> > >>>       ap_register_output_filter("FIXUP_HEADERS_ERR", ap_headers_error_filter,
> > >>>                                 NULL, AP_FTYPE_CONTENT_SET);
> > >>>       ap_hook_pre_config(header_pre_config,NULL,NULL,APR_HOOK_MIDDLE);
> > >>>       ap_hook_post_config(header_post_config,NULL,NULL,APR_HOOK_MIDDLE);
> > >>>       ap_hook_insert_filter(ap_headers_insert_output_filter, NULL,
NULL, APR_HOOK_LAST);
> > >>>       ap_hook_insert_error_filter(ap_headers_insert_error_filter,
> > >>>                                   NULL, NULL, APR_HOOK_LAST);
> > >>>       ap_hook_fixups(ap_headers_fixup, NULL, NULL, APR_HOOK_LAST);
> > >>>       ap_hook_post_read_request(ap_headers_early, NULL, NULL, APR_HOOK_FIRST);
> > >>> }
> > >>>
> > >>> module AP_MODULE_DECLARE_DATA headers_module =
> > >>> {
> > >>>       STANDARD20_MODULE_STUFF,
> > >>>       create_headers_dir_config,  /* dir config creater */
> > >>>       merge_headers_config,       /* dir merger --- default is to override
*/
> > >>>       NULL,                       /* server config */
> > >>>       NULL,                       /* merge server configs */
> > >>>       headers_cmds,               /* command apr_table_t */
> > >>>       register_hooks              /* register hooks */
> > >>> };
> > >>>
> > >>>
> > >>> The code I added is in the "ap_headers_insert_output_filter()" function.
> > >>>
> > >>>
> > >>> I did an "export SHOW_HOOKS=1" and ran the Apache, and I see this for
the modified mod_headers:
> > >>>
> > >>> Registering hooks for mod_headers.c
> > >>> mod_headers-jl V0.13 - use LIBCURL instead of OAM ASDK-process response
from callCurl
> > >>> In register_hooks
> > >>>     Hooked pre_config
> > >>>     Hooked post_config
> > >>>     Hooked insert_filter
> > >>>     Hooked insert_error_filter
> > >>>     Hooked fixups
> > >>>     Hooked post_read_request
> > >>>
> > >>>
> > >>> And for webgate, I see:
> > >>>
> > >>> Registering hooks for apache2entry_web_gate.cpp
> > >>>     Hooked post_config
> > >>>     Hooked handler
> > >>>     Hooked check_user_id
> > >>>     Hooked auth_checker
> > >>>
> > >>>
> > >>> I thought that the handler functions are called almost last part of
the processing (content generation), and my code is hooked to insert_filter, which I thought
occurs earlier than content generation, so shouldn't my code get processed BEFORE Apache attempts
to process the webgate functions?
> > >>>
> > >>> How can I get my code to process before the webgate does?
> > >>>
> > >>
> > >> insert_filter is run between the fixups and the handler hooks.
> > >>
> > >> Try to identify who is producing the variables that you need, in which
> > >> phase they are available at the earliest. Then identify which part of
> > >> web_gate hijacks the processing such that your code is not executed
> > >> anymore. I suppose it is one of web_gate's auth_checker or
> > >> check_user_id. If it was the web_gate handler then your code would have
> > >> run before.
> > >>
> > >> Sorin
> > >
> > >
> > > Hi Sorin,
> > >
> > > I posted a later msg that I've been trying do something along the lines that
you said:
> > >
> > > "I've been doing more testing, and it appears that the insert_filter hook (the
> > > "ap_headers_insert_output_filter()" function) is the only place where I can
put
> > > my code where it has access to the variables that it needs to do the processing
> > > that I'm doing.
> > >
> > > The problem is that if that other Oracle module is enabled in the Apache, it
> > > runs before my code, and I can't get the insert_filter hook (my function) to
get
> > > processed before the Oracle module "
> > 
> > The SSL variables are set in the fixups hook by mod_ssl. The fixups hook 
> > is run _after_ check_user_id and auth_checker. So you cannot rely on 
> > mod_ssl to populate the environment with the variables. I guess you'll 
> > have to get those variables yourself, before Oracle's check_user_id and 
> > auth_checker hooks.
> > 
> > Sorin
> 
> 
> Hi,
> 
> The original mod_headers code has a hook for fixups.  If I added an "after" string in
the code that registers my fixup function, with the name of the webgate, would that cause
my modified mod_headers to run before the webgate?
> 
> Also can you clarify/expand on what you mean by " you'll have to get those variables
yourself"?  I think that I'm currently getting them using env->setproc or something like
that.
> 
> Jim

Also which hooks run BEFORE auth_check?

Jim

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