components/web/apache2-modules/mod_dtrace/src/mod_dtrace.c

   1 /*
   2 * License:
   3 * Copyright 2004 The Apache Software Foundation
   4 *
   5 * Licensed under the Apache License, Version 2.0 (the "License");
   6 * you may not use this file except in compliance with the License.
   7 * You may obtain a copy of the License at
   8 *
   9 *     http://www.apache.org/licenses/LICENSE-2.0
  10 *
  11 * Unless required by applicable law or agreed to in writing, software
  12 * distributed under the License is distributed on an "AS IS" BASIS,
  13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 * See the License for the specific language governing permissions and
  15 * limitations under the License.
  16 *
  17 * Module Name: mod_dtrace
  18 *
  19 * Purpose: Apache implements a set of hooks and filters to allow
  20 *          modules to view and modify requests sent to the server.
  21 *          This module takes advantage of this architecture to
  22 *          implement several DTrace hooks.
  23 *
  24 * Notes: To get the most use out of the mod_dtrace Apache module, it will
  25 *        be useful to familiarize yourself with the Apache request_rec,
  26 *        server_rec and conn_rec structures. These can be viewed on the
  27 *        docx website:
  28 *
  29 *        http://docx.webperf.org/httpd_8h-source.html
  30 *
  31 *        A basic overview of each structure is included below:
  32 *
  33 *           request_rec : Contains all of the attributes (URI, filename,
  34 *                         method, bytes_sent) needed to describe an
  35 *                         HTTP request
  36 *
  37 *           conn_rec    : Stores the connection attributes including
  38 *                         IP addresses and ports
  39 *
  40 *           server_rec  : Stores information to describe each virtual server
  41 *
  42 * Last Modified: 02-08-2007
  43 *
  44 * Author: Matty < matty91 at gmail dot com >
  45 *
  46 * Version: 0.3a
  47 *
  48 * Release history:
  49 *
  50 *    0.3a: Fixed bug due to NULL values -- Sebastien Bouchex Bellomie
  51 *
  52 *    0.2a: Initial release
  53 *
  54 * Build instructions are available at the following site:
  55 *    http://prefetch.net/projects/apache_modtrace/build.txt
  56 *
  57 */
  58
  59 #include "ap_config.h"
  60 #include "httpd.h"
  61 #include "http_config.h"
  62 #include "http_connection.h"
  63 #include "http_protocol.h"
  64 #include "http_request.h"
  65 #include <sys/sdt.h>
  66
  67 module AP_MODULE_DECLARE_DATA dtrace_module;
  68
  69 /*
  70 *   Probe Function Purpoose:
  71 *   This probe will fire each time a request is send to the server.
  72 *
  73 *   arg0 -> address of the request_rec structure
  74 */
  75 int apache_receive_request(request_rec *r)
  76 {
  77     DTRACE_PROBE1(apache,
  78                   receive__request,
  79                   r);
  80
  81     return DECLINED;
  82 }
  83
  84 /*
  85 *   This probe will fire each time the web server invokes the logging handlers.
  86 *   Since the request_rec, server_rec and conn_rec should be completely filled
  87 *   in when this probe fires -- this will be a useful probe.
  88 *
  89 *   arg0 -> The address of the request_rec structure
  90 */
  91 int apache_log_request(request_rec *r)
  92 {
  93     /* apr_table_get will return the value of User-Agent or NULL */
  94     const char *userAgent = NULL;
  95     if (r->headers_in != NULL)
  96     {
  97         userAgent = apr_table_get(r->headers_in, "User-Agent");
  98     }
  99
 100     /* apr_table_get will return the value of Location or NULL */
 101     const char *redirectLocation = NULL;
 102     if (r->headers_out) {
 103         redirectLocation = apr_table_get(r->headers_out, "Location");
 104     }
 105
 106     DTRACE_PROBE3(apache,
 107                   log__request,
 108                   r,
 109                   userAgent,
 110                   redirectLocation);
 111
 112     return DECLINED;
 113 }
 114
 115 /*
 116 *  This probe will fire each time an httpd child process is created
 117 */
 118 void apache_create_child(apr_pool_t *p, server_rec *s)
 119 {
 120     DTRACE_PROBE(apache,
 121                  create__child);
 122 }
 123
 124 /*
 125 *   This probe will fire each time a new TCP connection is created
 126 *
 127 *   arg0 -> Client's IP address
 128 */
 129 int apache_accept_connection(conn_rec *c, void *csd)
 130 {
 131     DTRACE_PROBE1(apache,
 132                   accept__connection,
 133                   c);
 134
 135     return DECLINED;
 136 }
 137
 138 /*
 139 *   This probe will fire when the authentication stage is encountered
 140 *
 141 *   arg0 -> The address of the request_rec structure
 142 *
 143 */
 144 int apache_check_user(request_rec *r)
 145 {
 146     DTRACE_PROBE1(apache,
 147                   check__user__credentials,
 148                   r);
 149
 150     return DECLINED;
 151 }
 152
 153 /*
 154 *   This probe will fire when the access checking stage is encountered
 155 *
 156 *   arg0 -> The address of the request_rec structure
 157 *
 158 */
 159 int apache_check_access(request_rec *r)
 160 {
 161     DTRACE_PROBE1(apache,
 162                   check__access,
 163                   r);
 164
 165     return DECLINED;
 166 }
 167
 168 /*
 169 *   This probe will fire when the authorization checking stage is encountered
 170 *
 171 *   arg0 -> The address of the request_rec structure
 172 *
 173 */
 174 int apache_check_authorization(request_rec *r)
 175 {
 176     DTRACE_PROBE1(apache,
 177                   check__authorization,
 178                   r);
 179
 180     return DECLINED;
 181 }
 182
 183 /*
 184 *    Define the hooks and the functions registered to those hooks
 185 */
 186 void dtrace_register_hooks(apr_pool_t *p)
 187 {
 188     ap_hook_post_read_request(apache_receive_request,NULL,NULL,APR_HOOK_MIDDLE);
 189     ap_hook_child_init(apache_create_child,NULL, NULL, APR_HOOK_MIDDLE);
 190     ap_hook_pre_connection(apache_accept_connection,NULL, NULL, APR_HOOK_MIDDLE);
 191     ap_hook_check_user_id(apache_check_user,NULL,NULL,APR_HOOK_MIDDLE);
 192     ap_hook_access_checker(apache_check_access,NULL,NULL,APR_HOOK_MIDDLE);
 193     ap_hook_auth_checker(apache_check_authorization,NULL,NULL,APR_HOOK_MIDDLE);
 194     ap_hook_log_transaction(apache_log_request,NULL,NULL,APR_HOOK_MIDDLE);
 195 }
 196
 197 module AP_MODULE_DECLARE_DATA dtrace_module =
 198 {
 199     STANDARD20_MODULE_STUFF,
 200     NULL,
 201     NULL,
 202     NULL,
 203     NULL,
 204     NULL,
 205     dtrace_register_hooks
 206 };
 207
 208