/* 

* License:

* Copyright 2004 The Apache Software Foundation

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

*     http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*

* Module Name: mod_dtrace

*

* Purpose: Apache implements a set of hooks and filters to allow 

*          modules to view and modify requests sent to the server.

*          This module takes advantage of this architecture to 

*          implement several DTrace hooks.

*

* Notes: To get the most use out of the mod_dtrace Apache module, it will

*        be useful to familiarize yourself with the Apache request_rec,

*        server_rec and conn_rec structures. These can be viewed on the

*        docx website:

*

*        http://docx.webperf.org/httpd_8h-source.html

*

*        A basic overview of each structure is included below:

*

*           request_rec : Contains all of the attributes (URI, filename, 

*                         method, bytes_sent) needed to describe an

*                         HTTP request

*

*           conn_rec    : Stores the connection attributes including

*                         IP addresses and ports

*

*           server_rec  : Stores information to describe each virtual server

*

* Last Modified: 02-08-2007

*

* Author: Matty < matty91 at gmail dot com >

*

* Version: 0.3a

*

* Release history:

*

*    0.3a: Fixed bug due to NULL values -- Sebastien Bouchex Bellomie

*

*    0.2a: Initial release

*

* Build instructions are available at the following site:

*    http://prefetch.net/projects/apache_modtrace/build.txt

*

*/

#include "ap_config.h"

#include "httpd.h"

#include "http_config.h"

#include "http_connection.h"

#include "http_protocol.h"

#include "http_request.h"

#include <sys/sdt.h>

module AP_MODULE_DECLARE_DATA dtrace_module;

/* 

*   Probe Function Purpoose:

*   This probe will fire each time a request is send to the server. 

*

*   arg0 -> address of the request_rec structure 

*/

int apache_receive_request(request_rec *r)

{

    DTRACE_PROBE1(apache, 

                  receive__request, 

                  r);

    return DECLINED;

}

/* 

*   This probe will fire each time the web server invokes the logging handlers.

*   Since the request_rec, server_rec and conn_rec should be completely filled

*   in when this probe fires -- this will be a useful probe.

*   

*   arg0 -> The address of the request_rec structure

*/

int apache_log_request(request_rec *r)

{

    /* apr_table_get will return the value of User-Agent or NULL */

    const char *userAgent = NULL;

    if (r->headers_in != NULL)

    {

        userAgent = apr_table_get(r->headers_in, "User-Agent");

    }

    /* apr_table_get will return the value of Location or NULL */

    const char *redirectLocation = NULL;

    if (r->headers_out) {

        redirectLocation = apr_table_get(r->headers_out, "Location");

    }

    DTRACE_PROBE3(apache,

                  log__request,

                  r,

                  userAgent,

                  redirectLocation);

    return DECLINED;

}

/* 

*  This probe will fire each time an httpd child process is created 

*/

void apache_create_child(apr_pool_t *p, server_rec *s)

{

    DTRACE_PROBE(apache,

                 create__child);

}

/* 

*   This probe will fire each time a new TCP connection is created 

*

*   arg0 -> Client's IP address 

*/

int apache_accept_connection(conn_rec *c, void *csd)

{

    DTRACE_PROBE1(apache,

                  accept__connection,

                  c);

    return DECLINED;

}

/*

*   This probe will fire when the authentication stage is encountered

*

*   arg0 -> The address of the request_rec structure

*

*/

int apache_check_user(request_rec *r)

{

    DTRACE_PROBE1(apache,

                  check__user__credentials,

                  r);

    return DECLINED;

}

/*

*   This probe will fire when the access checking stage is encountered

*

*   arg0 -> The address of the request_rec structure

*

*/

int apache_check_access(request_rec *r)

{

    DTRACE_PROBE1(apache,

                  check__access,

                  r);

    return DECLINED;

}

/*

*   This probe will fire when the authorization checking stage is encountered

*

*   arg0 -> The address of the request_rec structure

*

*/

int apache_check_authorization(request_rec *r)

{

    DTRACE_PROBE1(apache,

                  check__authorization,

                  r);

    return DECLINED;

}

/*

*    Define the hooks and the functions registered to those hooks

*/

void dtrace_register_hooks(apr_pool_t *p)

{

    ap_hook_post_read_request(apache_receive_request,NULL,NULL,APR_HOOK_MIDDLE);

    ap_hook_child_init(apache_create_child,NULL, NULL, APR_HOOK_MIDDLE);

    ap_hook_pre_connection(apache_accept_connection,NULL, NULL, APR_HOOK_MIDDLE);

    ap_hook_check_user_id(apache_check_user,NULL,NULL,APR_HOOK_MIDDLE);

    ap_hook_access_checker(apache_check_access,NULL,NULL,APR_HOOK_MIDDLE);

    ap_hook_auth_checker(apache_check_authorization,NULL,NULL,APR_HOOK_MIDDLE);

    ap_hook_log_transaction(apache_log_request,NULL,NULL,APR_HOOK_MIDDLE);

}

module AP_MODULE_DECLARE_DATA dtrace_module =

{

    STANDARD20_MODULE_STUFF,

    NULL,

    NULL,

    NULL,

    NULL,

    NULL,

    dtrace_register_hooks

};