/*****************************************************************************
 *
 * NEBMODS.C - Event Broker Module Functions
 *
 *
 * License:
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *****************************************************************************/

#include "../include/config.h"
#include "../include/common.h"
#include "../include/nebmods.h"
#include "../include/neberrors.h"
#include "../include/nagios.h"


#ifdef USE_EVENT_BROKER


static nebmodule *neb_module_list;
static nebcallback **neb_callback_list;

/* compat stuff for USE_LTDL */
#ifdef USE_LTDL
# define dlopen(p, flags) lt_dlopen(p)
# define dlclose(p) lt_dlclose(p)
# define dlerror() lt_dlerror()
# define dlsym(hdl, sym) lt_dlsym(hdl, sym)
# define RTLD_NOW 0
# define RTLD_GLOBAL 0
#else
# define lt_dlinit() 0
# define lt_dlexit() 0
#endif

/****************************************************************************/
/****************************************************************************/
/* INITIALIZATION/CLEANUP FUNCTIONS                                         */
/****************************************************************************/
/****************************************************************************/

/* initialize module routines */
int neb_init_modules(void) {
	if(lt_dlinit())
		return ERROR;
	return OK;
	}


/* deinitialize module routines */
int neb_deinit_modules(void) {
	if(lt_dlexit())
		return ERROR;
	return OK;
	}


/* add a new module to module list */
int neb_add_module(char *filename, char *args, int should_be_loaded) {
	nebmodule *new_module = NULL;
	int x = OK;

	if(filename == NULL)
		return ERROR;

	/* allocate memory */
	new_module = (nebmodule *)calloc(1, sizeof(nebmodule));
	if(new_module == NULL)
		return ERROR;

	/* initialize vars */
	new_module->filename = (char *)strdup(filename);
	new_module->args = (args == NULL) ? NULL : (char *)strdup(args);
	new_module->should_be_loaded = should_be_loaded;
	new_module->is_currently_loaded = FALSE;
	for(x = 0; x < NEBMODULE_MODINFO_NUMITEMS; x++)
		new_module->info[x] = NULL;
	new_module->module_handle = NULL;
	new_module->init_func = NULL;
	new_module->deinit_func = NULL;

	/* add module to head of list */
	new_module->next = neb_module_list;
	neb_module_list = new_module;

	log_debug_info(DEBUGL_EVENTBROKER, 0, "Added module: name='%s', args='%s', should_be_loaded='%d'\n", filename, args, should_be_loaded);

	return OK;
	}


int neb_add_core_module(nebmodule *mod) {
	mod->should_be_loaded = FALSE;
	mod->is_currently_loaded = TRUE;
	mod->core_module = TRUE;
#ifdef USE_LTDL
	mod->module_handle = (lt_dlhandle)mod;
#else
	mod->module_handle = mod;
#endif
	mod->next = neb_module_list;
	neb_module_list = mod;
	return 0;
	}

/* free memory allocated to module list */
int neb_free_module_list(void) {
	nebmodule *temp_module = NULL;
	nebmodule *next_module = NULL;
	int x = OK;

	for(temp_module = neb_module_list; temp_module; temp_module = next_module) {
		next_module = temp_module->next;

		for(x = 0; x < NEBMODULE_MODINFO_NUMITEMS; x++)
			my_free(temp_module->info[x]);

		/* don't free this stuff for core modules */
		if (temp_module->core_module)
			continue;
		my_free(temp_module->filename);
		my_free(temp_module->args);
		my_free(temp_module);
		}

	neb_module_list = NULL;

	return OK;
	}



/****************************************************************************/
/****************************************************************************/
/* LOAD/UNLOAD FUNCTIONS                                                    */
/****************************************************************************/
/****************************************************************************/


/* load all modules */
int neb_load_all_modules(void) {
	nebmodule *temp_module = NULL;
	int ret, errors = 0;

	for(temp_module = neb_module_list; temp_module; temp_module = temp_module->next) {
		ret = neb_load_module(temp_module);
		if (ret != OK) {
			logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Failed to load module '%s'.\n", temp_module->filename ? temp_module->filename : "(no file?)");
			errors++;
			}
		}

	return errors ? ERROR : OK;
	}


/* load a particular module */
int neb_load_module(nebmodule *mod) {
	int (*initfunc)(int, char *, void *);
	int *module_version_ptr = NULL;
	int result = OK;

	if(mod == NULL)
		return ERROR;

	/* don't reopen the module */
	if(mod->is_currently_loaded == TRUE)
		return OK;

	/* don't load modules unless they should be loaded */
	if(mod->should_be_loaded == FALSE || mod->filename == NULL)
		return ERROR;

	/* load the module */
	mod->module_handle = dlopen(mod->filename, RTLD_NOW | RTLD_GLOBAL);
	if(mod->module_handle == NULL) {
		logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Could not load module '%s' -> %s\n", mod->filename, dlerror());

		return ERROR;
		}

	/* mark the module as being loaded */
	mod->is_currently_loaded = TRUE;

	/* find module API version */
	module_version_ptr = (int *)dlsym(mod->module_handle, "__neb_api_version");

	/* check the module API version */
	if(module_version_ptr == NULL || ((*module_version_ptr) != CURRENT_NEB_API_VERSION)) {

		logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Module '%s' is using an old or unspecified version of the event broker API.  Module will be unloaded.\n", mod->filename);

		neb_unload_module(mod, NEBMODULE_FORCE_UNLOAD, NEBMODULE_ERROR_API_VERSION);

		return ERROR;
		}

	/* locate the initialization function */
	mod->init_func = dlsym(mod->module_handle, "nebmodule_init");

	/* if the init function could not be located, unload the module */
	if(mod->init_func == NULL) {

		logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Could not locate nebmodule_init() in module '%s'.  Module will be unloaded.\n", mod->filename);

		neb_unload_module(mod, NEBMODULE_FORCE_UNLOAD, NEBMODULE_ERROR_NO_INIT);

		return ERROR;
		}

	/* run the module's init function */
	initfunc = mod->init_func;
	result = (*initfunc)(NEBMODULE_NORMAL_LOAD, mod->args, mod->module_handle);

	/* if the init function returned an error, unload the module */
	if(result != OK) {

		logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Function nebmodule_init() in module '%s' returned an error.  Module will be unloaded.\n", mod->filename);

		neb_unload_module(mod, NEBMODULE_FORCE_UNLOAD, NEBMODULE_ERROR_BAD_INIT);

		return ERROR;
		}

	logit(NSLOG_INFO_MESSAGE, TRUE, "Event broker module '%s' initialized successfully.\n", mod->filename);

	/* locate the de-initialization function (may or may not be present) */
	mod->deinit_func = dlsym(mod->module_handle, "nebmodule_deinit");

	log_debug_info(DEBUGL_EVENTBROKER, 0, "Module '%s' loaded with return code of '%d'\n", mod->filename, result);
	if(mod->deinit_func != NULL)
		log_debug_info(DEBUGL_EVENTBROKER, 0, "nebmodule_deinit() found\n");

	return OK;
	}


/* close (unload) all modules that are currently loaded */
int neb_unload_all_modules(int flags, int reason) {
	nebmodule *temp_module;

	for(temp_module = neb_module_list; temp_module; temp_module = temp_module->next) {

		/* skip modules that are not loaded */
		if(temp_module->is_currently_loaded == FALSE)
			continue;

		/* skip modules that do not have a valid handle */
		if(temp_module->module_handle == NULL)
			continue;

		/* close/unload the module */
		neb_unload_module(temp_module, flags, reason);
		}

	return OK;
	}



/* close (unload) a particular module */
int neb_unload_module(nebmodule *mod, int flags, int reason) {
	int (*deinitfunc)(int, int);
	int result = OK;

	if(mod == NULL)
		return ERROR;

	log_debug_info(DEBUGL_EVENTBROKER, 0, "Attempting to unload module '%s': flags=%d, reason=%d\n", mod->filename, flags, reason);

	/* remove the module's demand-loaded file */
	if(daemon_dumps_core == TRUE && mod->dl_file) {
		(void)unlink(mod->dl_file);
		my_free(mod->dl_file);
	}

	/* call the de-initialization function if available (and the module was initialized) */
	if(mod->deinit_func && reason != NEBMODULE_ERROR_BAD_INIT) {

		deinitfunc = mod->deinit_func;

		/* module can opt to not be unloaded */
		result = (*deinitfunc)(flags, reason);

		/* if module doesn't want to be unloaded, exit with error (unless its being forced) */
		if(result != OK && !(flags & NEBMODULE_FORCE_UNLOAD))
			return ERROR;
		}

	/* deregister all of the module's callbacks */
	neb_deregister_module_callbacks(mod);

	if(mod->core_module == FALSE) {

		/* unload the module */
		result = dlclose(mod->module_handle);

		if (result != 0) {
			logit(NSLOG_RUNTIME_ERROR, TRUE, "Error: Could not unload module '%s' -> %s\n", mod->filename, dlerror());
			return ERROR;
			}
		}

	/* mark the module as being unloaded */
	mod->is_currently_loaded = FALSE;

	log_debug_info(DEBUGL_EVENTBROKER, 0, "Module '%s' unloaded successfully.\n", mod->filename);

	logit(NSLOG_INFO_MESSAGE, FALSE, "Event broker module '%s' deinitialized successfully.\n", mod->filename);

	return OK;
	}




/****************************************************************************/
/****************************************************************************/
/* INFO FUNCTIONS                                                           */
/****************************************************************************/
/****************************************************************************/

/* sets module information */
int neb_set_module_info(void *handle, int type, char *data) {
	nebmodule *temp_module = NULL;

	if(handle == NULL)
		return NEBERROR_NOMODULE;

	/* check type */
	if(type < 0 || type >= NEBMODULE_MODINFO_NUMITEMS)
		return NEBERROR_MODINFOBOUNDS;

	/* find the module */
	for(temp_module = neb_module_list; temp_module != NULL; temp_module = temp_module->next) {
		if(temp_module->module_handle == handle)
			break;
		}
	if(temp_module == NULL)
		return NEBERROR_BADMODULEHANDLE;

	/* free any previously allocated memory */
	my_free(temp_module->info[type]);

	/* allocate memory for the new data */
	if((temp_module->info[type] = (char *)strdup(data)) == NULL)
		return NEBERROR_NOMEM;

	return OK;
	}



/****************************************************************************/
/****************************************************************************/
/* CALLBACK FUNCTIONS                                                       */
/****************************************************************************/
/****************************************************************************/

/* allows a module to register a callback function */
int neb_register_callback(int callback_type, void *mod_handle, int priority, int (*callback_func)(int, void *)) {
	nebmodule *temp_module = NULL;
	nebcallback *new_callback = NULL;
	nebcallback *temp_callback = NULL;
	nebcallback *last_callback = NULL;

	if(callback_func == NULL)
		return NEBERROR_NOCALLBACKFUNC;

	if(neb_callback_list == NULL)
		return NEBERROR_NOCALLBACKLIST;

	if(mod_handle == NULL)
		return NEBERROR_NOMODULEHANDLE;

	/* make sure the callback type is within bounds */
	if(callback_type < 0 || callback_type >= NEBCALLBACK_NUMITEMS)
		return NEBERROR_CALLBACKBOUNDS;

	/* make sure module handle is valid */
	for(temp_module = neb_module_list; temp_module; temp_module = temp_module->next) {
		if(temp_module->module_handle == mod_handle)
			break;
		}
	if(temp_module == NULL)
		return NEBERROR_BADMODULEHANDLE;

	/* allocate memory */
	new_callback = (nebcallback *)malloc(sizeof(nebcallback));
	if(new_callback == NULL)
		return NEBERROR_NOMEM;

	new_callback->priority = priority;
	new_callback->module_handle = mod_handle;
	new_callback->callback_func = callback_func;
	new_callback->next = NULL;

	/* add new function to callback list, sorted by priority (first come, first served for same priority) */
	
	for(last_callback = NULL, temp_callback = neb_callback_list[callback_type]; 
		temp_callback != NULL; 
		last_callback = temp_callback, temp_callback = temp_callback->next) {

		if(new_callback->priority < temp_callback->priority) {
			break;
			}
		}

	new_callback->next = temp_callback;
	if(last_callback == NULL) {
		neb_callback_list[callback_type] = new_callback;
		}
	else {
		last_callback->next = new_callback;
		}


	return OK;
	}



/* dregisters all callback functions for a given module */
int neb_deregister_module_callbacks(nebmodule *mod) {
	nebcallback *temp_callback = NULL;
	nebcallback *next_callback = NULL;
	int callback_type = 0;

	if(mod == NULL)
		return NEBERROR_NOMODULE;

	if(neb_callback_list == NULL)
		return OK;

	for(callback_type = 0; callback_type < NEBCALLBACK_NUMITEMS; callback_type++) {
		for(temp_callback = neb_callback_list[callback_type]; temp_callback != NULL; temp_callback = next_callback) {
			next_callback = temp_callback->next;
			if(temp_callback->module_handle == mod->module_handle)
				neb_deregister_callback(callback_type, (int(*)(int, void*))temp_callback->callback_func);
			}

		}

	return OK;
	}


/* allows a module to deregister a callback function */
int neb_deregister_callback(int callback_type, int (*callback_func)(int, void *)) {
	nebcallback *temp_callback = NULL;
	nebcallback *last_callback = NULL;
	nebcallback *next_callback = NULL;

	if(callback_func == NULL)
		return NEBERROR_NOCALLBACKFUNC;

	if(neb_callback_list == NULL)
		return NEBERROR_NOCALLBACKLIST;

	/* make sure the callback type is within bounds */
	if(callback_type < 0 || callback_type >= NEBCALLBACK_NUMITEMS)
		return NEBERROR_CALLBACKBOUNDS;

	/* find the callback to remove */
	for(temp_callback = last_callback = neb_callback_list[callback_type]; temp_callback != NULL; temp_callback = next_callback) {
		next_callback = temp_callback->next;

		/* we found it */
		if(temp_callback->callback_func == callback_func)
			break;

		last_callback = temp_callback;
		}

	/* we couldn't find the callback */
	if(temp_callback == NULL)
		return NEBERROR_CALLBACKNOTFOUND;

	else {
		/* only one item in the list */
		if(temp_callback != last_callback->next)
			neb_callback_list[callback_type] = NULL;
		else
			last_callback->next = next_callback;
		my_free(temp_callback);
		}

	return OK;
	}



/* make callbacks to modules */
int neb_make_callbacks(int callback_type, void *data) {
	nebcallback *temp_callback, *next_callback;
	int (*callbackfunc)(int, void *);
	register int cbresult = 0;
	int total_callbacks = 0;

	/* make sure callback list is initialized */
	if(neb_callback_list == NULL)
		return ERROR;

	/* make sure the callback type is within bounds */
	if(callback_type < 0 || callback_type >= NEBCALLBACK_NUMITEMS)
		return ERROR;

	log_debug_info(DEBUGL_EVENTBROKER, 1, "Making callbacks (type %d)...\n", callback_type);

	/* make the callbacks... */
	for(temp_callback = neb_callback_list[callback_type]; temp_callback; temp_callback = next_callback) {
		next_callback = temp_callback->next;
		callbackfunc = temp_callback->callback_func;
		cbresult = callbackfunc(callback_type, data);
		temp_callback = next_callback;

		total_callbacks++;
		log_debug_info(DEBUGL_EVENTBROKER, 2, "Callback #%d (type %d) return code = %d\n", total_callbacks, callback_type, cbresult);

		/* module wants to cancel callbacks to other modules (and potentially cancel the default Nagios handling of an event) */
		if(cbresult == NEBERROR_CALLBACKCANCEL)
			break;

		/* module wants to override default Nagios handling of an event */
		/* not sure if we should bail out here just because one module wants to override things - what about other modules? EG 12/11/2006 */
		else if(cbresult == NEBERROR_CALLBACKOVERRIDE)
			break;
		}

	return cbresult;
	}



/* initialize callback list */
int neb_init_callback_list(void) {
	register int x = 0;

	/* allocate memory for the callback list */
	neb_callback_list = (nebcallback **)malloc(NEBCALLBACK_NUMITEMS * sizeof(nebcallback *));
	if(neb_callback_list == NULL)
		return ERROR;

	/* initialize list pointers */
	for(x = 0; x < NEBCALLBACK_NUMITEMS; x++)
		neb_callback_list[x] = NULL;

	return OK;
	}


/* free memory allocated to callback list */
int neb_free_callback_list(void) {
	nebcallback *temp_callback = NULL;
	nebcallback *next_callback = NULL;
	register int x = 0;

	if(neb_callback_list == NULL)
		return OK;

	for(x = 0; x < NEBCALLBACK_NUMITEMS; x++) {

		for(temp_callback = neb_callback_list[x]; temp_callback != NULL; temp_callback = next_callback) {
			next_callback = temp_callback->next;
			my_free(temp_callback);
			}

		neb_callback_list[x] = NULL;
		}

	my_free(neb_callback_list);

	return OK;
	}

#endif