/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. */ /* * Apache example_hooks module. Provide demonstrations of how modules do things. * It is not meant to be used in a production server. Since it participates * in all of the processing phases, it could conceivable interfere with * the proper operation of other modules -- particularly the ones related * to security. * * In the interest of brevity, all functions and structures internal to * this module, but which may have counterparts in *real* modules, are * prefixed with 'x_' instead of 'example_'. * * To use mod_example_hooks, configure the Apache build with * --enable-example-hooks and compile. Set up a block in your * configuration file like so: * * * SetHandler example-hooks-handler * * * When you look at that location on your server, you will see a backtrace of * the callbacks that have been invoked up to that point. See the ErrorLog for * more information on code paths that touch mod_example_hooks. * * IMPORTANT NOTES * =============== * * Do NOT use this module on a production server. It attaches itself to every * phase of the server runtime operations including startup, shutdown and * request processing, and produces copious amounts of logging data. This will * negatively affect server performance. * * Do NOT use mod_example_hooks as the basis for your own code. This module * implements every callback hook offered by the Apache core, and your * module will almost certainly not have to implement this much. If you * want a simple module skeleton to start development, use apxs -g. * * XXX TO DO XXX * ============= * * * Enable HTML backtrace entries for more callbacks that are not directly * associated with a request * * Make sure every callback that posts an HTML backtrace entry does so in the * right category, so nothing gets overwritten * * Implement some logic to show what happens in the parent, and what in the * child(ren) */ #include "httpd.h" #include "http_config.h" #include "http_core.h" #include "http_log.h" #include "http_main.h" #include "http_protocol.h" #include "http_request.h" #include "util_script.h" #include "http_connection.h" #ifdef HAVE_UNIX_SUEXEC #include "unixd.h" #endif #include "scoreboard.h" #include "mpm_common.h" #include "apr_strings.h" #include /*--------------------------------------------------------------------------*/ /* */ /* Data declarations. */ /* */ /* Here are the static cells and structure declarations private to our */ /* module. */ /* */ /*--------------------------------------------------------------------------*/ /* * Sample configuration record. Used for both per-directory and per-server * configuration data. * * It's perfectly reasonable to have two different structures for the two * different environments. The same command handlers will be called for * both, though, so the handlers need to be able to tell them apart. One * possibility is for both structures to start with an int which is 0 for * one and 1 for the other. * * Note that while the per-directory and per-server configuration records are * available to most of the module handlers, they should be treated as * READ-ONLY by all except the command and merge handlers. Sometimes handlers * are handed a record that applies to the current location by implication or * inheritance, and modifying it will change the rules for other locations. */ typedef struct x_cfg { int cmode; /* Environment to which record applies * (directory, server, or combination). */ #define CONFIG_MODE_SERVER 1 #define CONFIG_MODE_DIRECTORY 2 #define CONFIG_MODE_COMBO 3 /* Shouldn't ever happen. */ int local; /* Boolean: "Example" directive declared * here? */ int congenital; /* Boolean: did we inherit an "Example"? */ char *trace; /* Pointer to trace string. */ char *loc; /* Location to which this record applies. */ } x_cfg; /* * String pointer to hold the startup trace. No harm working with a global until * the server is (may be) multi-threaded. */ static const char *trace = NULL; /* * Declare ourselves so the configuration routines can find and know us. * We'll fill it in at the end of the module. */ module AP_MODULE_DECLARE_DATA example_hooks_module; /*--------------------------------------------------------------------------*/ /* */ /* The following pseudo-prototype declarations illustrate the parameters */ /* passed to command handlers for the different types of directive */ /* syntax. If an argument was specified in the directive definition */ /* (look for "command_rec" below), it's available to the command handler */ /* via the (void *) info field in the cmd_parms argument passed to the */ /* handler (cmd->info for the examples below). */ /* */ /*--------------------------------------------------------------------------*/ /* * Command handler for a NO_ARGS directive. Declared in the command_rec * list with * AP_INIT_NO_ARGS("directive", function, mconfig, where, help) * * static const char *handle_NO_ARGS(cmd_parms *cmd, void *mconfig); */ /* * Command handler for a RAW_ARGS directive. The "args" argument is the text * of the commandline following the directive itself. Declared in the * command_rec list with * AP_INIT_RAW_ARGS("directive", function, mconfig, where, help) * * static const char *handle_RAW_ARGS(cmd_parms *cmd, void *mconfig, * const char *args); */ /* * Command handler for a FLAG directive. The single parameter is passed in * "bool", which is either zero or not for Off or On respectively. * Declared in the command_rec list with * AP_INIT_FLAG("directive", function, mconfig, where, help) * * static const char *handle_FLAG(cmd_parms *cmd, void *mconfig, int bool); */ /* * Command handler for a TAKE1 directive. The single parameter is passed in * "word1". Declared in the command_rec list with * AP_INIT_TAKE1("directive", function, mconfig, where, help) * * static const char *handle_TAKE1(cmd_parms *cmd, void *mconfig, * char *word1); */ /* * Command handler for a TAKE2 directive. TAKE2 commands must always have * exactly two arguments. Declared in the command_rec list with * AP_INIT_TAKE2("directive", function, mconfig, where, help) * * static const char *handle_TAKE2(cmd_parms *cmd, void *mconfig, * char *word1, char *word2); */ /* * Command handler for a TAKE3 directive. Like TAKE2, these must have exactly * three arguments, or the parser complains and doesn't bother calling us. * Declared in the command_rec list with * AP_INIT_TAKE3("directive", function, mconfig, where, help) * * static const char *handle_TAKE3(cmd_parms *cmd, void *mconfig, * char *word1, char *word2, char *word3); */ /* * Command handler for a TAKE12 directive. These can take either one or two * arguments. * - word2 is a NULL pointer if no second argument was specified. * Declared in the command_rec list with * AP_INIT_TAKE12("directive", function, mconfig, where, help) * * static const char *handle_TAKE12(cmd_parms *cmd, void *mconfig, * char *word1, char *word2); */ /* * Command handler for a TAKE123 directive. A TAKE123 directive can be given, * as might be expected, one, two, or three arguments. * - word2 is a NULL pointer if no second argument was specified. * - word3 is a NULL pointer if no third argument was specified. * Declared in the command_rec list with * AP_INIT_TAKE123("directive", function, mconfig, where, help) * * static const char *handle_TAKE123(cmd_parms *cmd, void *mconfig, * char *word1, char *word2, char *word3); */ /* * Command handler for a TAKE13 directive. Either one or three arguments are * permitted - no two-parameters-only syntax is allowed. * - word2 and word3 are NULL pointers if only one argument was specified. * Declared in the command_rec list with * AP_INIT_TAKE13("directive", function, mconfig, where, help) * * static const char *handle_TAKE13(cmd_parms *cmd, void *mconfig, * char *word1, char *word2, char *word3); */ /* * Command handler for a TAKE23 directive. At least two and as many as three * arguments must be specified. * - word3 is a NULL pointer if no third argument was specified. * Declared in the command_rec list with * AP_INIT_TAKE23("directive", function, mconfig, where, help) * * static const char *handle_TAKE23(cmd_parms *cmd, void *mconfig, * char *word1, char *word2, char *word3); */ /* * Command handler for a ITERATE directive. * - Handler is called once for each of n arguments given to the directive. * - word1 points to each argument in turn. * Declared in the command_rec list with * AP_INIT_ITERATE("directive", function, mconfig, where, help) * * static const char *handle_ITERATE(cmd_parms *cmd, void *mconfig, * char *word1); */ /* * Command handler for a ITERATE2 directive. * - Handler is called once for each of the second and subsequent arguments * given to the directive. * - word1 is the same for each call for a particular directive instance (the * first argument). * - word2 points to each of the second and subsequent arguments in turn. * Declared in the command_rec list with * AP_INIT_ITERATE2("directive", function, mconfig, where, help) * * static const char *handle_ITERATE2(cmd_parms *cmd, void *mconfig, * char *word1, char *word2); */ /*--------------------------------------------------------------------------*/ /* */ /* These routines are strictly internal to this module, and support its */ /* operation. They are not referenced by any external portion of the */ /* server. */ /* */ /*--------------------------------------------------------------------------*/ /* * Locate our directory configuration record for the current request. */ static x_cfg *our_dconfig(const request_rec *r) { return (x_cfg *) ap_get_module_config(r->per_dir_config, &example_hooks_module); } /* * The following utility routines are not used in the module. Don't * compile them so -Wall doesn't complain about functions that are * defined but not used. */ #if 0 /* * Locate our server configuration record for the specified server. */ static x_cfg *our_sconfig(const server_rec *s) { return (x_cfg *) ap_get_module_config(s->module_config, &example_hooks_module); } /* * Likewise for our configuration record for the specified request. */ static x_cfg *our_rconfig(const request_rec *r) { return (x_cfg *) ap_get_module_config(r->request_config, &example_hooks_module); } #endif /* if 0 */ /* * Likewise for our configuration record for a connection. */ static x_cfg *our_cconfig(const conn_rec *c) { return (x_cfg *) ap_get_module_config(c->conn_config, &example_hooks_module); } /* * You *could* change the following if you wanted to see the calling * sequence reported in the server's error_log, but beware - almost all of * these co-routines are called for every single request, and the impact * on the size (and readability) of the error_log is considerable. */ #ifndef EXAMPLE_LOG_EACH #define EXAMPLE_LOG_EACH 0 #endif #if EXAMPLE_LOG_EACH static void example_log_each(apr_pool_t *p, server_rec *s, const char *note) { if (s != NULL) { ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02991) "mod_example_hooks: %s", note); } else { apr_file_t *out = NULL; apr_file_open_stderr(&out, p); apr_file_printf(out, "mod_example_hooks traced in non-loggable " "context: %s\n", note); } } #endif /* * This utility routine traces the hooks called when the server starts up. * It leaves a trace in a global variable, so it should not be called from * a hook handler that runs in a multi-threaded situation. */ static void trace_startup(apr_pool_t *p, server_rec *s, x_cfg *mconfig, const char *note) { const char *sofar; char *where, *addon; #if EXAMPLE_LOG_EACH example_log_each(p, s, note); #endif /* * If we weren't passed a configuration record, we can't figure out to * what location this call applies. This only happens for co-routines * that don't operate in a particular directory or server context. If we * got a valid record, extract the location (directory or server) to which * it applies. */ where = (mconfig != NULL) ? mconfig->loc : "nowhere"; where = (where != NULL) ? where : ""; addon = apr_pstrcat(p, "
  • \n" "
    \n" "
    ", note, "
    \n" "
    [", where, "]
    \n" "
    \n" "
  • \n", NULL); /* * Make sure that we start with a valid string, even if we have never been * called. */ sofar = (trace == NULL) ? "" : trace; trace = apr_pstrcat(p, sofar, addon, NULL); } /* * This utility route traces the hooks called as a request is handled. * It takes the current request as argument */ #define TRACE_NOTE "example-hooks-trace" static void trace_request(const request_rec *r, const char *note) { const char *trace_copy, *sofar; char *addon, *where; x_cfg *cfg; #if EXAMPLE_LOG_EACH example_log_each(r->pool, r->server, note); #endif if ((sofar = apr_table_get(r->notes, TRACE_NOTE)) == NULL) { sofar = ""; } cfg = our_dconfig(r); where = (cfg != NULL) ? cfg->loc : "nowhere"; where = (where != NULL) ? where : ""; addon = apr_pstrcat(r->pool, "
  • \n" "
    \n" "
    ", note, "
    \n" "
    [", where, "]
    \n" "
    \n" "
  • \n", NULL); trace_copy = apr_pstrcat(r->pool, sofar, addon, NULL); apr_table_set(r->notes, TRACE_NOTE, trace_copy); } /* * This utility routine traces the hooks called while processing a * Connection. Its trace is kept in the pool notes of the pool associated * with the Connection. */ /* * Key to get and set the userdata. We should be able to get away * with a constant key, since in prefork mode the process will have * the connection and its pool to itself entirely, and in * multi-threaded mode each connection will have its own pool. */ #define CONN_NOTE "example-hooks-connection" static void trace_connection(conn_rec *c, const char *note) { const char *trace_copy, *sofar; char *addon, *where; void *data; x_cfg *cfg; #if EXAMPLE_LOG_EACH example_log_each(c->pool, c->base_server, note); #endif cfg = our_cconfig(c); where = (cfg != NULL) ? cfg->loc : "nowhere"; where = (where != NULL) ? where : ""; addon = apr_pstrcat(c->pool, "
  • \n" "
    \n" "
    ", note, "
    \n" "
    [", where, "]
    \n" "
    \n" "
  • \n", NULL); /* Find existing notes and copy */ apr_pool_userdata_get(&data, CONN_NOTE, c->pool); sofar = (data == NULL) ? "" : (const char *) data; /* Tack addon onto copy */ trace_copy = apr_pstrcat(c->pool, sofar, addon, NULL); /* * Stash copy back into pool notes. This call has a cleanup * parameter, but we're not using it because the string has been * allocated from that same pool. There is also an unused return * value: we have nowhere to communicate any error that might * occur, and will have to check for the existence of this data on * the other end. */ apr_pool_userdata_set((const void *) trace_copy, CONN_NOTE, NULL, c->pool); } static void trace_nocontext(apr_pool_t *p, const char *file, int line, const char *note) { /* * Since we have no request or connection to trace, or any idea * from where this routine was called, there's really not much we * can do. If we are not logging everything by way of the * EXAMPLE_LOG_EACH constant, do nothing in this routine. */ #ifdef EXAMPLE_LOG_EACH ap_log_perror(file, line, APLOG_MODULE_INDEX, APLOG_NOTICE, 0, p, "%s", note); #endif } /*--------------------------------------------------------------------------*/ /* We prototyped the various syntax for command handlers (routines that */ /* are called when the configuration parser detects a directive declared */ /* by our module) earlier. Now we actually declare a "real" routine that */ /* will be invoked by the parser when our "real" directive is */ /* encountered. */ /* */ /* If a command handler encounters a problem processing the directive, it */ /* signals this fact by returning a non-NULL pointer to a string */ /* describing the problem. */ /* */ /* The magic return value DECLINE_CMD is used to deal with directives */ /* that might be declared by multiple modules. If the command handler */ /* returns NULL, the directive was processed; if it returns DECLINE_CMD, */ /* the next module (if any) that declares the directive is given a chance */ /* at it. If it returns any other value, it's treated as the text of an */ /* error message. */ /*--------------------------------------------------------------------------*/ /* * Command handler for the NO_ARGS "Example" directive. All we do is mark the * call in the trace log, and flag the applicability of the directive to the * current location in that location's configuration record. */ static const char *cmd_example(cmd_parms *cmd, void *mconfig) { x_cfg *cfg = (x_cfg *) mconfig; /* * "Example Wuz Here" */ cfg->local = 1; trace_startup(cmd->pool, cmd->server, cfg, "cmd_example()"); return NULL; } /* * This function gets called to create a per-directory configuration * record. This will be called for the "default" server environment, and for * each directory for which the parser finds any of our directives applicable. * If a directory doesn't have any of our directives involved (i.e., they * aren't in the .htaccess file, or a , , or related * block), this routine will *not* be called - the configuration for the * closest ancestor is used. * * The return value is a pointer to the created module-specific * structure. */ static void *x_create_dir_config(apr_pool_t *p, char *dirspec) { x_cfg *cfg; char *dname = dirspec; char *note; /* * Allocate the space for our record from the pool supplied. */ cfg = (x_cfg *) apr_pcalloc(p, sizeof(x_cfg)); /* * Now fill in the defaults. If there are any `parent' configuration * records, they'll get merged as part of a separate callback. */ cfg->local = 0; cfg->congenital = 0; cfg->cmode = CONFIG_MODE_DIRECTORY; /* * Finally, add our trace to the callback list. */ dname = (dname != NULL) ? dname : ""; cfg->loc = apr_pstrcat(p, "DIR(", dname, ")", NULL); note = apr_psprintf(p, "x_create_dir_config(p == %pp, dirspec == %s)", (void*) p, dirspec); trace_startup(p, NULL, cfg, note); return (void *) cfg; } /* * This function gets called to merge two per-directory configuration * records. This is typically done to cope with things like .htaccess files * or directives for directories that are beneath one for which a * configuration record was already created. The routine has the * responsibility of creating a new record and merging the contents of the * other two into it appropriately. If the module doesn't declare a merge * routine, the record for the closest ancestor location (that has one) is * used exclusively. * * The routine MUST NOT modify any of its arguments! * * The return value is a pointer to the created module-specific structure * containing the merged values. */ static void *x_merge_dir_config(apr_pool_t *p, void *parent_conf, void *newloc_conf) { x_cfg *merged_config = (x_cfg *) apr_pcalloc(p, sizeof(x_cfg)); x_cfg *pconf = (x_cfg *) parent_conf; x_cfg *nconf = (x_cfg *) newloc_conf; char *note; /* * Some things get copied directly from the more-specific record, rather * than getting merged. */ merged_config->local = nconf->local; merged_config->loc = apr_pstrdup(p, nconf->loc); /* * Others, like the setting of the `congenital' flag, get ORed in. The * setting of that particular flag, for instance, is TRUE if it was ever * true anywhere in the upstream configuration. */ merged_config->congenital = (pconf->congenital | pconf->local); /* * If we're merging records for two different types of environment (server * and directory), mark the new record appropriately. Otherwise, inherit * the current value. */ merged_config->cmode = (pconf->cmode == nconf->cmode) ? pconf->cmode : CONFIG_MODE_COMBO; /* * Now just record our being called in the trace list. Include the * locations we were asked to merge. */ note = apr_psprintf(p, "x_merge_dir_config(p == %pp, parent_conf == " "%pp, newloc_conf == %pp)", (void*) p, (void*) parent_conf, (void*) newloc_conf); trace_startup(p, NULL, merged_config, note); return (void *) merged_config; } /* * This function gets called to create a per-server configuration * record. It will always be called for the "default" server. * * The return value is a pointer to the created module-specific * structure. */ static void *x_create_server_config(apr_pool_t *p, server_rec *s) { x_cfg *cfg; char *sname = s->server_hostname; /* * As with the x_create_dir_config() reoutine, we allocate and fill * in an empty record. */ cfg = (x_cfg *) apr_pcalloc(p, sizeof(x_cfg)); cfg->local = 0; cfg->congenital = 0; cfg->cmode = CONFIG_MODE_SERVER; /* * Note that we were called in the trace list. */ sname = (sname != NULL) ? sname : ""; cfg->loc = apr_pstrcat(p, "SVR(", sname, ")", NULL); trace_startup(p, s, cfg, "x_create_server_config()"); return (void *) cfg; } /* * This function gets called to merge two per-server configuration * records. This is typically done to cope with things like virtual hosts and * the default server configuration The routine has the responsibility of * creating a new record and merging the contents of the other two into it * appropriately. If the module doesn't declare a merge routine, the more * specific existing record is used exclusively. * * The routine MUST NOT modify any of its arguments! * * The return value is a pointer to the created module-specific structure * containing the merged values. */ static void *x_merge_server_config(apr_pool_t *p, void *server1_conf, void *server2_conf) { x_cfg *merged_config = (x_cfg *) apr_pcalloc(p, sizeof(x_cfg)); x_cfg *s1conf = (x_cfg *) server1_conf; x_cfg *s2conf = (x_cfg *) server2_conf; char *note; /* * Our inheritance rules are our own, and part of our module's semantics. * Basically, just note whence we came. */ merged_config->cmode = (s1conf->cmode == s2conf->cmode) ? s1conf->cmode : CONFIG_MODE_COMBO; merged_config->local = s2conf->local; merged_config->congenital = (s1conf->congenital | s1conf->local); merged_config->loc = apr_pstrdup(p, s2conf->loc); /* * Trace our call, including what we were asked to merge. */ note = apr_pstrcat(p, "x_merge_server_config(\"", s1conf->loc, "\",\"", s2conf->loc, "\")", NULL); trace_startup(p, NULL, merged_config, note); return (void *) merged_config; } /*--------------------------------------------------------------------------* * * * Now let's declare routines for each of the callback hooks in order. * * (That's the order in which they're listed in the callback list, *not * * the order in which the server calls them! See the command_rec * * declaration near the bottom of this file.) Note that these may be * * called for situations that don't relate primarily to our function - in * * other words, the fixup handler shouldn't assume that the request has * * to do with "example_hooks" stuff. * * * * With the exception of the content handler, all of our routines will be * * called for each request, unless an earlier handler from another module * * aborted the sequence. * * * * There are three types of hooks (see include/ap_config.h): * * * * VOID : No return code, run all handlers declared by any module * * RUN_FIRST : Run all handlers until one returns something other * * than DECLINED. Hook runner result is result of last callback * * RUN_ALL : Run all handlers until one returns something other than OK * * or DECLINED. The hook runner returns that other value. If * * all hooks run, the hook runner returns OK. * * * * Handlers that are declared as "int" can return the following: * * * * OK Handler accepted the request and did its thing with it. * * DECLINED Handler took no action. * * HTTP_mumble Handler looked at request and found it wanting. * * * * See include/httpd.h for a list of HTTP_mumble status codes. Handlers * * that are not declared as int return a valid pointer, or NULL if they * * DECLINE to handle their phase for that specific request. Exceptions, if * * any, are noted with each routine. * *--------------------------------------------------------------------------*/ /* * This routine is called before the server processes the configuration * files. There is no return value. */ static int x_pre_config(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp) { /* * Log the call and exit. */ trace_startup(pconf, NULL, NULL, "x_pre_config()"); return OK; } /* * This routine is called after the server processes the configuration * files. At this point the module may review and adjust its configuration * settings in relation to one another and report any problems. On restart, * this routine will be called twice, once in the startup process (which * exits shortly after this phase) and once in the running server process. * * The return value is OK, DECLINED, or HTTP_mumble. If we return OK, the * server will still call any remaining modules with an handler for this * phase. */ static int x_check_config(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s) { /* * Log the call and exit. */ trace_startup(pconf, s, NULL, "x_check_config()"); return OK; } /* * This routine is called when the -t command-line option is supplied. * It executes only once, in the startup process, after the check_config * phase and just before the process exits. At this point the module * may output any information useful in configuration testing. * * This is a VOID hook: all defined handlers get called. */ static void x_test_config(apr_pool_t *pconf, server_rec *s) { apr_file_t *out = NULL; apr_file_open_stderr(&out, pconf); apr_file_printf(out, "Example module configuration test routine\n"); trace_startup(pconf, s, NULL, "x_test_config()"); } /* * This routine is called to perform any module-specific log file * openings. It is invoked just before the post_config phase * * The return value is OK, DECLINED, or HTTP_mumble. If we return OK, the * server will still call any remaining modules with an handler for this * phase. */ static int x_open_logs(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s) { /* * Log the call and exit. */ trace_startup(pconf, s, NULL, "x_open_logs()"); return OK; } /* * This routine is called after the server finishes the configuration * process. At this point the module may review and adjust its configuration * settings in relation to one another and report any problems. On restart, * this routine will be called only once, in the running server process. * * The return value is OK, DECLINED, or HTTP_mumble. If we return OK, the * server will still call any remaining modules with an handler for this * phase. */ static int x_post_config(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s) { /* * Log the call and exit. */ trace_startup(pconf, s, NULL, "x_post_config()"); return OK; } /* * All our process-death routine does is add its trace to the log. */ static apr_status_t x_child_exit(void *data) { char *note; server_rec *s = data; char *sname = s->server_hostname; /* * The arbitrary text we add to our trace entry indicates for which server * we're being called. */ sname = (sname != NULL) ? sname : ""; note = apr_pstrcat(s->process->pool, "x_child_exit(", sname, ")", NULL); trace_startup(s->process->pool, s, NULL, note); return APR_SUCCESS; } /* * All our process initialiser does is add its trace to the log. * * This is a VOID hook: all defined handlers get called. */ static void x_child_init(apr_pool_t *p, server_rec *s) { char *note; char *sname = s->server_hostname; /* * The arbitrary text we add to our trace entry indicates for which server * we're being called. */ sname = (sname != NULL) ? sname : ""; note = apr_pstrcat(p, "x_child_init(", sname, ")", NULL); trace_startup(p, s, NULL, note); apr_pool_cleanup_register(p, s, x_child_exit, x_child_exit); } /* * The hook runner for ap_hook_http_scheme is aliased to ap_http_scheme(), * a routine that the core and other modules call when they need to know * the URL scheme for the request. For instance, mod_ssl returns "https" * if the server_rec associated with the request has SSL enabled. * * This hook was named 'ap_hook_http_method' in httpd 2.0. * * This is a RUN_FIRST hook: the first handler to return a non NULL * value aborts the handler chain. The http_core module inserts a * fallback handler (with APR_HOOK_REALLY_LAST preference) that returns * "http". */ static const char *x_http_scheme(const request_rec *r) { /* * Log the call and exit. */ trace_request(r, "x_http_scheme()"); /* We have no claims to make about the request scheme */ return NULL; } /* * The runner for this hook is aliased to ap_default_port(), which the * core and other modules call when they need to know the default port * for a particular server. This is used for instance to omit the * port number from a Redirect response Location header URL if the port * number is equal to the default port for the service (like 80 for http). * * This is a RUN_FIRST hook: the first handler to return a non-zero * value is the last one executed. The http_core module inserts a * fallback handler (with APR_HOOK_REALLY_LAST order specifier) that * returns 80. */ static apr_port_t x_default_port(const request_rec *r) { /* * Log the call and exit. */ trace_request(r, "x_default_port()"); return 0; } /* * This routine is called just before the handler gets invoked. It allows * a module to insert a previously defined filter into the filter chain. * * No filter has been defined by this module, so we just log the call * and exit. * * This is a VOID hook: all defined handlers get called. */ static void x_insert_filter(request_rec *r) { /* * Log the call and exit. */ trace_request(r, "x_insert_filter()"); } /* * This routine is called to insert a previously defined error filter into * the filter chain as the request is being processed. * * For the purpose of this example, we don't have a filter to insert, * so just add to the trace and exit. * * This is a VOID hook: all defined handlers get called. */ static void x_insert_error_filter(request_rec *r) { trace_request(r, "x_insert_error_filter()"); } /*--------------------------------------------------------------------------*/ /* */ /* Now we declare our content handlers, which are invoked when the server */ /* encounters a document which our module is supposed to have a chance to */ /* see. (See mod_mime's SetHandler and AddHandler directives, and the */ /* mod_info and mod_status examples, for more details.) */ /* */ /* Since content handlers are dumping data directly into the connection */ /* (using the r*() routines, such as rputs() and rprintf()) without */ /* intervention by other parts of the server, they need to make */ /* sure any accumulated HTTP headers are sent first. This is done by */ /* calling send_http_header(). Otherwise, no header will be sent at all, */ /* and the output sent to the client will actually be HTTP-uncompliant. */ /*--------------------------------------------------------------------------*/ /* * Sample content handler. All this does is display the call list that has * been built up so far. * * This routine gets called for every request, unless another handler earlier * in the callback chain has already handled the request. It is up to us to * test the request_rec->handler field and see whether we are meant to handle * this request. * * The content handler gets to write directly to the client using calls like * ap_rputs() and ap_rprintf() * * This is a RUN_FIRST hook. */ static int x_handler(request_rec *r) { x_cfg *dcfg; char *note; void *conn_data; apr_status_t status; dcfg = our_dconfig(r); /* * Add our trace to the log, and whether we get to write * content for this request. */ note = apr_pstrcat(r->pool, "x_handler(), handler is \"", r->handler, "\"", NULL); trace_request(r, note); /* If it's not for us, get out as soon as possible. */ if (strcmp(r->handler, "example-hooks-handler")) { return DECLINED; } /* * Set the Content-type header. Note that we do not actually have to send * the headers: this is done by the http core. */ ap_set_content_type(r, "text/html"); /* * If we're only supposed to send header information (HEAD request), we're * already there. */ if (r->header_only) { return OK; } /* * Now send our actual output. Since we tagged this as being * "text/html", we need to embed any HTML. */ ap_rputs(DOCTYPE_HTML_3_2, r); ap_rputs("\n", r); ap_rputs(" \n", r); ap_rputs(" mod_example_hooks Module Content-Handler Output\n", r); ap_rputs(" \n", r); ap_rputs(" \n", r); ap_rputs(" \n", r); ap_rputs("

    mod_example_hooks Module Content-Handler Output\n", r); ap_rputs("

    \n", r); ap_rputs("

    \n", r); ap_rprintf(r, " Apache HTTP Server version: \"%s\"\n", ap_get_server_banner()); ap_rputs("
    \n", r); ap_rprintf(r, " Server built: \"%s\"\n", ap_get_server_built()); ap_rputs("

    \n", r); ap_rputs("

    \n", r); ap_rputs(" The format for the callback trace is:\n", r); ap_rputs("

    \n", r); ap_rputs("
    \n", r); ap_rputs("
    n.<routine-name>", r); ap_rputs("(<routine-data>)\n", r); ap_rputs("
    \n", r); ap_rputs("
    [<applies-to>]\n", r); ap_rputs("
    \n", r); ap_rputs("
    \n", r); ap_rputs("

    \n", r); ap_rputs(" The <routine-data> is supplied by\n", r); ap_rputs(" the routine when it requests the trace,\n", r); ap_rputs(" and the <applies-to> is extracted\n", r); ap_rputs(" from the configuration record at the time of the trace.\n", r); ap_rputs(" SVR() indicates a server environment\n", r); ap_rputs(" (blank means the main or default server, otherwise it's\n", r); ap_rputs(" the name of the VirtualHost); DIR()\n", r); ap_rputs(" indicates a location in the URL or filesystem\n", r); ap_rputs(" namespace.\n", r); ap_rputs("

    \n", r); ap_rprintf(r, "

    Startup callbacks so far:

    \n
      \n%s
    \n", trace); ap_rputs("

    Connection-specific callbacks so far:

    \n", r); status = apr_pool_userdata_get(&conn_data, CONN_NOTE, r->connection->pool); if ((status == APR_SUCCESS) && conn_data) { ap_rprintf(r, "
      \n%s
    \n", (char *) conn_data); } else { ap_rputs("

    No connection-specific callback information was " "retrieved.

    \n", r); } ap_rputs("

    Request-specific callbacks so far:

    \n", r); ap_rprintf(r, "
      \n%s
    \n", apr_table_get(r->notes, TRACE_NOTE)); ap_rputs("

    Environment for this call:

    \n", r); ap_rputs("
      \n", r); ap_rprintf(r, "
    • Applies-to: %s\n
    • \n", dcfg->loc); ap_rprintf(r, "
    • \"Example\" directive declared here: %s\n
    • \n", (dcfg->local ? "YES" : "NO")); ap_rprintf(r, "
    • \"Example\" inherited: %s\n
    • \n", (dcfg->congenital ? "YES" : "NO")); ap_rputs("
    \n", r); ap_rputs(" \n", r); ap_rputs("\n", r); /* * We're all done, so cancel the timeout we set. Since this is probably * the end of the request we *could* assume this would be done during * post-processing - but it's possible that another handler might be * called and inherit our outstanding timer. Not good; to each its own. */ /* * We did what we wanted to do, so tell the rest of the server we * succeeded. */ return OK; } /* * The quick_handler hook presents modules with a very powerful opportunity to * serve their content in a very early request phase. Note that this handler * can not serve any requests from the file system because hooks like * map_to_storage have not run. The quick_handler hook also runs before any * authentication and access control. * * This hook is used by mod_cache to serve cached content. * * This is a RUN_FIRST hook. Return OK if you have served the request, * DECLINED if you want processing to continue, or a HTTP_* error code to stop * processing the request. */ static int x_quick_handler(request_rec *r, int lookup_uri) { /* * Log the call and exit. */ trace_request(r, "x_quick_handler()"); return DECLINED; } /* * This routine is called just after the server accepts the connection, * but before it is handed off to a protocol module to be served. The point * of this hook is to allow modules an opportunity to modify the connection * as soon as possible. The core server uses this phase to setup the * connection record based on the type of connection that is being used. * * This is a RUN_ALL hook. */ static int x_pre_connection(conn_rec *c, void *csd) { char *note; /* * Log the call and exit. */ note = apr_psprintf(c->pool, "x_pre_connection(c = %pp, p = %pp)", (void*) c, (void*) c->pool); trace_connection(c, note); return OK; } /* This routine is used to actually process the connection that was received. * Only protocol modules should implement this hook, as it gives them an * opportunity to replace the standard HTTP processing with processing for * some other protocol. Both echo and POP3 modules are available as * examples. * * This is a RUN_FIRST hook. */ static int x_process_connection(conn_rec *c) { trace_connection(c, "x_process_connection()"); return DECLINED; } /* * This routine is called after the request has been read but before any other * phases have been processed. This allows us to make decisions based upon * the input header fields. * * This is a HOOK_VOID hook. */ static void x_pre_read_request(request_rec *r, conn_rec *c) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_pre_read_request()"); } /* * This routine is called after the request has been read but before any other * phases have been processed. This allows us to make decisions based upon * the input header fields. * * This is a RUN_ALL hook. */ static int x_post_read_request(request_rec *r) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_post_read_request()"); return DECLINED; } /* * This routine gives our module an opportunity to translate the URI into an * actual filename, before URL decoding happens. * * This is a RUN_FIRST hook. */ static int x_pre_translate_name(request_rec *r) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_pre_translate_name()"); return DECLINED; } /* * This routine gives our module an opportunity to translate the URI into an * actual filename. If we don't do anything special, the server's default * rules (Alias directives and the like) will continue to be followed. * * This is a RUN_FIRST hook. */ static int x_translate_name(request_rec *r) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_translate_name()"); return DECLINED; } /* * This routine maps r->filename to a physical file on disk. Useful for * overriding default core behavior, including skipping mapping for * requests that are not file based. * * This is a RUN_FIRST hook. */ static int x_map_to_storage(request_rec *r) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_map_to_storage()"); return DECLINED; } /* * this routine gives our module another chance to examine the request * headers and to take special action. This is the first phase whose * hooks' configuration directives can appear inside the * and similar sections, because at this stage the URI has been mapped * to the filename. For example this phase can be used to block evil * clients, while little resources were wasted on these. * * This is a RUN_ALL hook. */ static int x_header_parser(request_rec *r) { /* * We don't actually *do* anything here, except note the fact that we were * called. */ trace_request(r, "x_header_parser()"); return DECLINED; } /* * This routine is called to check for any module-specific restrictions placed * upon the requested resource. (See the mod_access_compat module for an * example.) * * This is a RUN_ALL hook. The first handler to return a status other than OK * or DECLINED (for instance, HTTP_FORBIDDEN) aborts the callback chain. */ static int x_check_access(request_rec *r) { trace_request(r, "x_check_access()"); return DECLINED; } /* * This routine is called to check the authentication information sent with * the request (such as looking up the user in a database and verifying that * the [encrypted] password sent matches the one in the database). * * This is a RUN_FIRST hook. The return value is OK, DECLINED, or some * HTTP_mumble error (typically HTTP_UNAUTHORIZED). */ static int x_check_authn(request_rec *r) { /* * Don't do anything except log the call. */ trace_request(r, "x_check_authn()"); return DECLINED; } /* * This routine is called to check to see if the resource being requested * requires authorisation. * * This is a RUN_FIRST hook. The return value is OK, DECLINED, or * HTTP_mumble. If we return OK, no other modules are called during this * phase. * * If *all* modules return DECLINED, the request is aborted with a server * error. */ static int x_check_authz(request_rec *r) { /* * Log the call and return OK, or access will be denied (even though we * didn't actually do anything). */ trace_request(r, "x_check_authz()"); return DECLINED; } /* * This routine is called to determine and/or set the various document type * information bits, like Content-type (via r->content_type), language, et * cetera. * * This is a RUN_FIRST hook. */ static int x_type_checker(request_rec *r) { /* * Log the call, but don't do anything else - and report truthfully that * we didn't do anything. */ trace_request(r, "x_type_checker()"); return DECLINED; } /* * This routine is called to perform any module-specific fixing of header * fields, et cetera. It is invoked just before any content-handler. * * This is a RUN_ALL HOOK. */ static int x_fixups(request_rec *r) { /* * Log the call and exit. */ trace_request(r, "x_fixups()"); return DECLINED; } /* * This routine is called to perform any module-specific logging activities * over and above the normal server things. * * This is a RUN_ALL hook. */ static int x_log_transaction(request_rec *r) { trace_request(r, "x_log_transaction()"); return DECLINED; } #ifdef HAVE_UNIX_SUEXEC /* * This routine is called to find out under which user id to run suexec * Unless our module runs CGI programs, there is no reason for us to * mess with this information. * * This is a RUN_FIRST hook. The return value is a pointer to an * ap_unix_identity_t or NULL. */ static ap_unix_identity_t *x_get_suexec_identity(const request_rec *r) { trace_request(r, "x_get_suexec_identity()"); return NULL; } #endif /* * This routine is called to create a connection. This hook is implemented * by the Apache core: there is no known reason a module should override * it. * * This is a RUN_FIRST hook. * * Return NULL to decline, a valid conn_rec pointer to accept. */ static conn_rec *x_create_connection(apr_pool_t *p, server_rec *server, apr_socket_t *csd, long conn_id, void *sbh, apr_bucket_alloc_t *alloc) { trace_nocontext(p, __FILE__, __LINE__, "x_create_connection()"); return NULL; } /* * This hook is defined in server/core.c, but it is not actually called * or documented. * * This is a RUN_ALL hook. */ static int x_get_mgmt_items(apr_pool_t *p, const char *val, apr_hash_t *ht) { /* We have nothing to do here but trace the call, and no context * in which to trace it. */ trace_nocontext(p, __FILE__, __LINE__, "x_check_config()"); return DECLINED; } /* * This routine gets called shortly after the request_rec structure * is created. It provides the opportunity to manipulae the request * at a very early stage. * * This is a RUN_ALL hook. */ static int x_create_request(request_rec *r) { /* * We have a request_rec, but it is not filled in enough to give * us a usable configuration. So, add a trace without context. */ trace_nocontext( r->pool, __FILE__, __LINE__, "x_create_request()"); return DECLINED; } /* * This routine gets called during the startup of the MPM. * No known existing module implements this hook. * * This is a RUN_ALL hook. */ static int x_pre_mpm(apr_pool_t *p, ap_scoreboard_e sb_type) { trace_nocontext(p, __FILE__, __LINE__, "x_pre_mpm()"); return DECLINED; } /* * This hook gets run periodically by a maintenance function inside * the MPM. Its exact purpose is unknown and undocumented at this time. * * This is a RUN_ALL hook. */ static int x_monitor(apr_pool_t *p, server_rec *s) { trace_nocontext(p, __FILE__, __LINE__, "x_monitor()"); return DECLINED; } /*--------------------------------------------------------------------------*/ /* */ /* Which functions are responsible for which hooks in the server. */ /* */ /*--------------------------------------------------------------------------*/ /* * Each function our module provides to handle a particular hook is * specified here. The functions are registered using * ap_hook_foo(name, predecessors, successors, position) * where foo is the name of the hook. * * The args are as follows: * name -> the name of the function to call. * predecessors -> a list of modules whose calls to this hook must be * invoked before this module. * successors -> a list of modules whose calls to this hook must be * invoked after this module. * position -> The relative position of this module. One of * APR_HOOK_FIRST, APR_HOOK_MIDDLE, or APR_HOOK_LAST. * Most modules will use APR_HOOK_MIDDLE. If multiple * modules use the same relative position, Apache will * determine which to call first. * If your module relies on another module to run first, * or another module running after yours, use the * predecessors and/or successors. * * The number in brackets indicates the order in which the routine is called * during request processing. Note that not all routines are necessarily * called (such as if a resource doesn't have access restrictions). * The actual delivery of content to the browser [9] is not handled by * a hook; see the handler declarations below. */ static void x_register_hooks(apr_pool_t *p) { trace = NULL; ap_hook_pre_config(x_pre_config, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_check_config(x_check_config, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_test_config(x_test_config, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_open_logs(x_open_logs, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_post_config(x_post_config, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_child_init(x_child_init, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_handler(x_handler, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_quick_handler(x_quick_handler, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_pre_connection(x_pre_connection, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_process_connection(x_process_connection, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_pre_read_request(x_pre_read_request, NULL, NULL, APR_HOOK_MIDDLE); /* [1] post read_request handling */ ap_hook_post_read_request(x_post_read_request, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_log_transaction(x_log_transaction, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_http_scheme(x_http_scheme, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_default_port(x_default_port, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_pre_translate_name(x_pre_translate_name, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_translate_name(x_translate_name, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_map_to_storage(x_map_to_storage, NULL,NULL, APR_HOOK_MIDDLE); ap_hook_header_parser(x_header_parser, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_fixups(x_fixups, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_type_checker(x_type_checker, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_check_access(x_check_access, NULL, NULL, APR_HOOK_MIDDLE, AP_AUTH_INTERNAL_PER_CONF); ap_hook_check_authn(x_check_authn, NULL, NULL, APR_HOOK_MIDDLE, AP_AUTH_INTERNAL_PER_CONF); ap_hook_check_authz(x_check_authz, NULL, NULL, APR_HOOK_MIDDLE, AP_AUTH_INTERNAL_PER_CONF); ap_hook_insert_filter(x_insert_filter, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_insert_error_filter(x_insert_error_filter, NULL, NULL, APR_HOOK_MIDDLE); #ifdef HAVE_UNIX_SUEXEC ap_hook_get_suexec_identity(x_get_suexec_identity, NULL, NULL, APR_HOOK_MIDDLE); #endif ap_hook_create_connection(x_create_connection, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_get_mgmt_items(x_get_mgmt_items, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_create_request(x_create_request, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_pre_mpm(x_pre_mpm, NULL, NULL, APR_HOOK_MIDDLE); ap_hook_monitor(x_monitor, NULL, NULL, APR_HOOK_MIDDLE); } /*--------------------------------------------------------------------------*/ /* */ /* All of the routines have been declared now. Here's the list of */ /* directives specific to our module, and information about where they */ /* may appear and how the command parser should pass them to us for */ /* processing. Note that care must be taken to ensure that there are NO */ /* collisions of directive names between modules. */ /* */ /*--------------------------------------------------------------------------*/ /* * List of directives specific to our module. */ static const command_rec x_cmds[] = { AP_INIT_NO_ARGS( "Example", /* directive name */ cmd_example, /* config action routine */ NULL, /* argument to include in call */ OR_OPTIONS, /* where available */ "Example directive - no arguments" /* directive description */ ), {NULL} }; /*--------------------------------------------------------------------------*/ /* */ /* Finally, the list of callback routines and data structures that provide */ /* the static hooks into our module from the other parts of the server. */ /* */ /*--------------------------------------------------------------------------*/ /* * Module definition for configuration. If a particular callback is not * needed, replace its routine name below with the word NULL. */ AP_DECLARE_MODULE(example_hooks) = { STANDARD20_MODULE_STUFF, x_create_dir_config, /* per-directory config creator */ x_merge_dir_config, /* dir config merger */ x_create_server_config, /* server config creator */ x_merge_server_config, /* server config merger */ x_cmds, /* command table */ x_register_hooks, /* set up other request processing hooks */ };