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From Sorin Manolache <sor...@gmail.com>
Subject Re: Confused about modules processing order...
Date Tue, 26 Jun 2012 07:29:27 GMT
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

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