Protocol converter module
Hi everybody, I am attempting to write a module that implements a binary protocol that is not http and is not fully request and response based using apache. I have looked at mode echo and some others and I have Nick Kew's book. I want my module to convert incoming messages into http requests so that Apache is going to serve them using normal application server infrastructure. This is what I, based on the info I have can easily do using an input and output filter. What I also need the protocol to be able to do is to send messages to the client with no incoming data from the client. This may be based on a timeout or based on a request coming from somewhere else (a tier-2 application server sending me a request on a totally different connection). >From what I have read so far, I could not find a hook that allows me to do so. The only way that I could figure out how to do that is to modify http_core.c and in ap_process_http_sync_connection query for either the timeout or the separate even to have occured using some shared memory technique. This however does not feel right to me. I would ideally like to keep using http_core as it is without touching it. Is there a way for me to wake up trigger the input filter chain even when there is no data on the actual connection? I could then create a request from the context of my persistent connection for a handler that I have written that triggers the output filter chain to send the correct message. Or even better is there a way I can trigger the output filter chain? Are there hooks for this purpose? I would very much appreciate a hint in the right direction. Best regards, Robert
Re: Change Request-Header before mod_rewrite
On 2012-06-04 22:53, Marc apocalypse17 wrote:
Hi all,
I just developed my first apache module following the tutorial on the apache
website. The module is responsible for adding one header value to the active
request which must be checked in a mod_rewrite ReWriteCondition.
The problem is, that this value never reaches the mod_rewrite Rule. The Header
just behaves the same as the original request. Does anyone know why? What am I
doing wrong?
My module looks like this:
static int helloworld_handler(request_rec* r){
if (!r->main) {
apr_table_setn(r->headers_in, "X-CUSTOM-HEADER", "1");
}
return DECLINED;
}
static void register_hooks(apr_pool_t* pool){
ap_hook_handler(helloworld_handler, NULL, NULL, APR_HOOK_FIRST);
}
module AP_MODULE_DECLARE_DATA helloworld_module = {
STANDARD20_MODULE_STUFF,
NULL,
NULL,
NULL,
NULL,
example_directives,
register_hooks
};
The .htacces file looks like this:
RewriteEngine on
RewriteCond %{HTTP:X-CUSTOM-HEADER} 1 [NC]
RewriteRule from.html to.html
The Rewrite-Rule is never executes fine. It always show the content of
from.html.
A server-wide RewriteRule is executed in the translate_name hook.
A directory-wide RewriteRule is executed in the fixups hook.
So you'll have to place a callback on the translate_name or on the
fixups hook and make sure your callback is executed before mod_rewrite's.
You could also try to set the header using the RequestHeader directive
of the mod_headers module. Use the option "early".
http://httpd.apache.org/docs/2.2/mod/mod_headers.html#requestheader
--
Sorin
Thank you in advance,
Marc
Re: Change Request-Header before mod_rewrite
On 06/04/2012 10:53 PM, Marc apocalypse17 wrote:
> Hi all,
>
> I just developed my first apache module following the tutorial on the apache
> website. The module is responsible for adding one header value to the active
> request which must be checked in a mod_rewrite ReWriteCondition.
> The problem is, that this value never reaches the mod_rewrite Rule. The
> Header just behaves the same as the original request. Does anyone know why?
> What am I doing wrong?
>
> My module looks like this:
>
> static int helloworld_handler(request_rec* r){
> if (!r->main) {
> apr_table_setn(r->headers_in, "X-CUSTOM-HEADER", "1");
> }
> return DECLINED;
> }
>
> static void register_hooks(apr_pool_t* pool){
> ap_hook_handler(helloworld_handler, NULL, NULL, APR_HOOK_FIRST);
> }
>
> module AP_MODULE_DECLARE_DATA helloworld_module = {
> STANDARD20_MODULE_STUFF,
> NULL,
> NULL,
> NULL,
> NULL,
> example_directives,
> register_hooks
> };
>
> The .htacces file looks like this:
>
> RewriteEngine on
> RewriteCond %{HTTP:X-CUSTOM-HEADER} 1 [NC]
> RewriteRule from.html to.html
>
> The Rewrite-Rule is never executes fine. It always show the content of
> from.html.
>
>
> Thank you in advance,
> Marc
>
As Ben said, mod_rewrite is invoked far earlier than your handler
(handlers are invoked last), since it hooks onto the translation part of
the http process. If you intend for your module to do the same, you
change your hook function accordingly:
static void register_hooks(apr_pool_t* pool){
ap_hook_translate_name(helloworld_handler, NULL, NULL, APR_HOOK_FIRST-1);
}
This will eventually be covered by the module guide in the docs (as soon
as I get some time off to write it)
With regards,
Daniel.
Re: Change Request-Header before mod_rewrite
On Mon, Jun 4, 2012 at 10:53 PM, Marc apocalypse17 wrote:
> Hi all,
>
> I just developed my first apache module following the tutorial on the apache
> website. The module is responsible for adding one header value to the active
> request which must be checked in a mod_rewrite ReWriteCondition.
> The problem is, that this value never reaches the mod_rewrite Rule. The
> Header just behaves the same as the original request. Does anyone know why?
> What am I doing wrong?
>
> My module looks like this:
>
> static int helloworld_handler(request_rec* r){
> if (!r->main) {
> apr_table_setn(r->headers_in, "X-CUSTOM-HEADER", "1");
> }
> return DECLINED;
> }
>
> static void register_hooks(apr_pool_t* pool){
> ap_hook_handler(helloworld_handler, NULL, NULL, APR_HOOK_FIRST);
> }
>
> module AP_MODULE_DECLARE_DATA helloworld_module = {
> STANDARD20_MODULE_STUFF,
> NULL,
> NULL,
> NULL,
> NULL,
> example_directives,
> register_hooks
> };
>
> The .htacces file looks like this:
>
> RewriteEngine on
> RewriteCond %{HTTP:X-CUSTOM-HEADER} 1 [NC]
> RewriteRule from.html to.html
>
> The Rewrite-Rule is never executes fine. It always show the content of
> from.html.
>
>
> Thank you in advance,
> Marc
mod_rewrite.c does most of the interesting work in a translate_name
hook. By the time your handler hooks run, it's probably too late.
Change Request-Header before mod_rewrite
Hi all,
I just developed my first apache module following the tutorial on the apache
website. The module is responsible for adding one header value to the active
request which must be checked in a mod_rewrite ReWriteCondition.
The problem is, that this value never reaches the mod_rewrite Rule. The Header
just behaves the same as the original request. Does anyone know why? What am I
doing wrong?
My module looks like this:
static int helloworld_handler(request_rec* r){
if (!r->main) {
apr_table_setn(r->headers_in, "X-CUSTOM-HEADER", "1");
}
return DECLINED;
}
static void register_hooks(apr_pool_t* pool){
ap_hook_handler(helloworld_handler, NULL, NULL, APR_HOOK_FIRST);
}
module AP_MODULE_DECLARE_DATA helloworld_module = {
STANDARD20_MODULE_STUFF,
NULL,
NULL,
NULL,
NULL,
example_directives,
register_hooks
};
The .htacces file looks like this:
RewriteEngine on
RewriteCond %{HTTP:X-CUSTOM-HEADER} 1 [NC]
RewriteRule from.html to.html
The Rewrite-Rule is never executes fine. It always show the content of
from.html.
Thank you in advance,
Marc
--
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