1 files changed, 509 insertions, 0 deletions

diff --git a/src/knot/conf/module.c b/src/knot/conf/module.c
new file mode 100644
index 0000000..d5d9642
--- /dev/null
+++ b/src/knot/conf/module.c
@@ -0,0 +1,509 @@
+/*  Copyright (C) 2023 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <glob.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <urcu.h>
+
+#include "knot/conf/conf.h"
+#include "knot/conf/confio.h"
+#include "knot/conf/module.h"
+#include "knot/common/log.h"
+#include "knot/modules/static_modules.h"
+#include "knot/nameserver/query_module.h"
+#include "contrib/openbsd/strlcat.h"
+#include "contrib/string.h"
+
+#define LIB_EXTENSION ".so"
+
+knot_dynarray_define(mod, module_t *, DYNARRAY_VISIBILITY_NORMAL)
+knot_dynarray_define(old_schema, yp_item_t *, DYNARRAY_VISIBILITY_NORMAL)
+
+static module_t STATIC_MODULES[] = {
+	STATIC_MODULES_INIT
+	{ NULL }
+};
+
+module_t *conf_mod_find(
+	conf_t *conf,
+	const char *name,
+	size_t len,
+	bool temporary)
+{
+	if (conf == NULL || name == NULL) {
+		return NULL;
+	}
+
+	// First, search in static modules.
+	for (module_t *mod = STATIC_MODULES; mod->api != NULL; mod++) {
+		if (strncmp(name, mod->api->name, len) == 0) {
+			return mod;
+		}
+	}
+
+	module_type_t excluded_type = temporary ? MOD_EXPLICIT : MOD_TEMPORARY;
+
+	// Second, search in dynamic modules.
+	knot_dynarray_foreach(mod, module_t *, module, conf->modules) {
+		if ((*module) != NULL && (*module)->type != excluded_type &&
+		    strncmp(name, (*module)->api->name, len) == 0) {
+			return (*module);
+		}
+	}
+
+	return NULL;
+}
+
+static int mod_load(
+	conf_t *conf,
+	module_t *mod)
+{
+	static const yp_item_t module_common[] = {
+		{ C_ID,      YP_TSTR,  YP_VNONE, CONF_IO_FREF },
+		{ C_COMMENT, YP_TSTR,  YP_VNONE },
+		{ NULL }
+	};
+
+	yp_item_t *sub_items = NULL;
+
+	int ret;
+	if (mod->api->config != NULL) {
+		ret = yp_schema_merge(&sub_items, module_common, mod->api->config);
+	} else {
+		ret = yp_schema_copy(&sub_items, module_common);
+	}
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Synthesise module config section name. */
+	const size_t name_len = strlen(mod->api->name);
+	if (name_len > YP_MAX_ITEM_NAME_LEN) {
+		return KNOT_YP_EINVAL_ITEM;
+	}
+	char name[1 + YP_MAX_ITEM_NAME_LEN + 1];
+	name[0] = name_len;
+	memcpy(name + 1, mod->api->name, name_len + 1);
+
+	const yp_item_t schema[] = {
+		{ name, YP_TGRP, YP_VGRP = { sub_items },
+		        YP_FALLOC | YP_FMULTI | CONF_IO_FRLD_MOD | CONF_IO_FRLD_ZONES,
+		        { mod->api->config_check } },
+		{ NULL }
+	};
+
+	yp_item_t *merged = NULL;
+	ret = yp_schema_merge(&merged, conf->schema, schema);
+	yp_schema_free(sub_items);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Update configuration schema (with lazy free).
+	yp_item_t **current_schema = &conf->schema;
+	yp_item_t *old_schema = rcu_xchg_pointer(current_schema, merged);
+	synchronize_rcu();
+	old_schema_dynarray_add(&conf->old_schemas, &old_schema);
+
+	return KNOT_EOK;
+}
+
+int conf_mod_load_common(
+	conf_t *conf)
+{
+	if (conf == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = KNOT_EOK;
+
+	// First, load static modules.
+	for (module_t *mod = STATIC_MODULES; mod->api != NULL; mod++) {
+		ret = mod_load(conf, mod);
+		if (ret != KNOT_EOK) {
+			log_error("module '%s', failed to load (%s)",
+			          mod->api->name, knot_strerror(ret));
+			break;
+		}
+
+		log_debug("module '%s', loaded static", mod->api->name);
+	}
+
+	// Second, try to load implicit shared modules if configured.
+	if (strlen(MODULE_DIR) > 0) {
+		struct stat path_stat;
+		glob_t glob_buf = { 0 };
+
+		char *path = sprintf_alloc("%s/*%s", MODULE_DIR, LIB_EXTENSION);
+		if (path == NULL) {
+			ret = KNOT_ENOMEM;
+		} else if (stat(MODULE_DIR, &path_stat) != 0 ||
+		           !S_ISDIR(path_stat.st_mode)) {
+			if (errno == ENOENT) {
+				// Module directory doesn't exist.
+				ret = KNOT_EOK;
+			} else {
+				log_error("module, invalid directory '%s'",
+				          MODULE_DIR);
+				ret = KNOT_EINVAL;
+			}
+		} else if (access(MODULE_DIR, F_OK | R_OK) != 0) {
+			log_error("module, failed to access directory '%s'",
+			          MODULE_DIR);
+			ret = KNOT_EACCES;
+		} else {
+			ret = glob(path, 0, NULL, &glob_buf);
+			if (ret != 0 && ret != GLOB_NOMATCH) {
+				log_error("module, failed to read directory '%s'",
+				          MODULE_DIR);
+				ret = KNOT_EACCES;
+			} else {
+				ret = KNOT_EOK;
+			}
+		}
+
+		// Process each module in the directory.
+		for (size_t i = 0; i < glob_buf.gl_pathc; i++) {
+			(void)conf_mod_load_extra(conf, NULL, glob_buf.gl_pathv[i],
+			                          MOD_IMPLICIT);
+		}
+
+		globfree(&glob_buf);
+		free(path);
+	}
+
+	conf_mod_load_purge(conf, false);
+
+	return ret;
+}
+
+int conf_mod_load_extra(
+	conf_t *conf,
+	const char *mod_name,
+	const char *file_name,
+	module_type_t type)
+{
+	if (conf == NULL || (mod_name == NULL && file_name == NULL)) {
+		return KNOT_EINVAL;
+	}
+
+	// Synthesize module file name if not specified.
+	char *tmp_name = NULL;
+	if (file_name == NULL) {
+		tmp_name = sprintf_alloc("%s/%s%s", MODULE_INSTDIR,
+		                         mod_name + strlen(KNOTD_MOD_NAME_PREFIX),
+		                         LIB_EXTENSION);
+		if (tmp_name == NULL) {
+			return KNOT_ENOMEM;
+		}
+		file_name = tmp_name;
+	}
+
+	void *handle = dlopen(file_name, RTLD_NOW | RTLD_LOCAL);
+	if (handle == NULL) {
+		log_error("module, failed to open '%s' (%s)", file_name, dlerror());
+		free(tmp_name);
+		return KNOT_ENOENT;
+	}
+	(void)dlerror();
+
+	knotd_mod_api_t *api = dlsym(handle, "knotd_mod_api");
+	if (api == NULL) {
+		char *err = dlerror();
+		if (err == NULL) {
+			err = "empty symbol";
+		}
+		log_error("module, invalid library '%s' (%s)", file_name, err);
+		dlclose(handle);
+		free(tmp_name);
+		return KNOT_ENOENT;
+	}
+	free(tmp_name);
+
+	if (api->version != KNOTD_MOD_ABI_VERSION) {
+		log_error("module '%s', incompatible version", api->name);
+		dlclose(handle);
+		return KNOT_ENOTSUP;
+	}
+
+	if (api->name == NULL || (mod_name != NULL && strcmp(api->name, mod_name) != 0)) {
+		log_error("module '%s', module name mismatch", api->name);
+		dlclose(handle);
+		return KNOT_ENOTSUP;
+	}
+
+	// Check if the module is already loaded.
+	module_t *found = conf_mod_find(conf, api->name, strlen(api->name),
+	                                type == MOD_TEMPORARY);
+	if (found != NULL) {
+		log_error("module '%s', duplicate module", api->name);
+		dlclose(handle);
+		return KNOT_EEXIST;
+	}
+
+	module_t *mod = calloc(1, sizeof(*mod));
+	if (mod == NULL) {
+		dlclose(handle);
+		return KNOT_ENOMEM;
+	}
+	mod->api = api;
+	mod->lib_handle = handle;
+	mod->type = type;
+
+	int ret = mod_load(conf, mod);
+	if (ret != KNOT_EOK) {
+		log_error("module '%s', failed to load (%s)", api->name,
+		          knot_strerror(ret));
+		dlclose(handle);
+		free(mod);
+		return ret;
+	}
+
+	mod_dynarray_add(&conf->modules, &mod);
+
+	log_debug("module '%s', loaded shared", api->name);
+
+	return KNOT_EOK;
+}
+
+static void unload_shared(
+	module_t *mod)
+{
+	if (mod != NULL) {
+		assert(mod->lib_handle);
+		(void)dlclose(mod->lib_handle);
+		free(mod);
+	}
+}
+
+void conf_mod_load_purge(
+	conf_t *conf,
+	bool temporary)
+{
+	if (conf == NULL) {
+		return;
+	}
+
+	// Switch the current temporary schema with the initial one.
+	if (temporary && conf->old_schemas.size > 0) {
+		yp_item_t **current_schema = &conf->schema;
+		yp_item_t **initial = &(conf->old_schemas.arr(&conf->old_schemas))[0];
+
+		yp_item_t *old_schema = rcu_xchg_pointer(current_schema, *initial);
+		synchronize_rcu();
+		*initial = old_schema;
+	}
+
+	knot_dynarray_foreach(old_schema, yp_item_t *, schema, conf->old_schemas) {
+		yp_schema_free(*schema);
+	}
+	old_schema_dynarray_free(&conf->old_schemas);
+
+	knot_dynarray_foreach(mod, module_t *, module, conf->modules) {
+		if ((*module) != NULL && (*module)->type == MOD_TEMPORARY) {
+			unload_shared((*module));
+			*module = NULL; // Cannot remove from dynarray.
+		}
+	}
+}
+
+void conf_mod_unload_shared(
+	conf_t *conf)
+{
+	if (conf == NULL) {
+		return;
+	}
+
+	knot_dynarray_foreach(mod, module_t *, module, conf->modules) {
+		unload_shared((*module));
+	}
+	mod_dynarray_free(&conf->modules);
+}
+
+#define LOG_ARGS(mod_id, msg) "module '%s%s%.*s', " msg, \
+	mod_id->name + 1, (mod_id->len > 0) ? "/" : "", (int)mod_id->len, \
+	mod_id->data
+
+#define MOD_ID_LOG(zone, level, mod_id, msg, ...) \
+	if (zone != NULL) \
+		log_zone_##level(zone, LOG_ARGS(mod_id, msg), ##__VA_ARGS__); \
+	else \
+		log_##level(LOG_ARGS(mod_id, msg), ##__VA_ARGS__);
+
+void conf_activate_modules(
+	conf_t *conf,
+	struct server *server,
+	const knot_dname_t *zone_name,
+	list_t *query_modules,
+	struct query_plan **query_plan)
+{
+	int ret = KNOT_EOK;
+
+	if (conf == NULL || query_modules == NULL || query_plan == NULL) {
+		ret = KNOT_EINVAL;
+		goto activate_error;
+	}
+
+	conf_val_t val;
+
+	// Get list of associated modules.
+	if (zone_name != NULL) {
+		val = conf_zone_get(conf, C_MODULE, zone_name);
+	} else {
+		val = conf_default_get(conf, C_GLOBAL_MODULE);
+	}
+
+	switch (val.code) {
+	case KNOT_EOK:
+		break;
+	case KNOT_ENOENT: // Check if a module is configured at all.
+	case KNOT_YP_EINVAL_ID:
+		return;
+	default:
+		ret = val.code;
+		goto activate_error;
+	}
+
+	// Create query plan.
+	*query_plan = query_plan_create();
+	if (*query_plan == NULL) {
+		ret = KNOT_ENOMEM;
+		goto activate_error;
+	}
+
+	// Initialize query modules list.
+	init_list(query_modules);
+
+	// Open the modules.
+	while (val.code == KNOT_EOK) {
+		conf_mod_id_t *mod_id = conf_mod_id(&val);
+		if (mod_id == NULL) {
+			ret = KNOT_ENOMEM;
+			goto activate_error;
+		}
+
+		// Open the module.
+		knotd_mod_t *mod = query_module_open(conf, server, mod_id, *query_plan,
+		                                     zone_name);
+		if (mod == NULL) {
+			MOD_ID_LOG(zone_name, error, mod_id, "failed to open");
+			conf_free_mod_id(mod_id);
+			goto skip_module;
+		}
+
+		// Check the module scope.
+		if ((zone_name == NULL && !(mod->api->flags & KNOTD_MOD_FLAG_SCOPE_GLOBAL)) ||
+		    (zone_name != NULL && !(mod->api->flags & KNOTD_MOD_FLAG_SCOPE_ZONE))) {
+			MOD_ID_LOG(zone_name, error, mod_id, "out of scope");
+			query_module_close(mod);
+			goto skip_module;
+		}
+
+		// Check if the module is loadable.
+		if (mod->api->load == NULL) {
+			MOD_ID_LOG(zone_name, debug, mod_id, "empty module, not loaded");
+			query_module_close(mod);
+			goto skip_module;
+		}
+
+		// Load the module.
+		ret = mod->api->load(mod);
+		if (ret != KNOT_EOK) {
+			MOD_ID_LOG(zone_name, error, mod_id, "failed to load (%s)",
+			        knot_strerror(ret));
+			query_module_close(mod);
+			goto skip_module;
+		}
+		mod->config = NULL; // Invalidate the current config.
+
+		add_tail(query_modules, &mod->node);
+skip_module:
+		conf_val_next(&val);
+	}
+
+	return;
+activate_error:
+	CONF_LOG(LOG_ERR, "failed to activate modules (%s)", knot_strerror(ret));
+}
+
+void conf_deactivate_modules(
+	list_t *query_modules,
+	struct query_plan **query_plan)
+{
+	if (query_modules == NULL || query_plan == NULL) {
+		return;
+	}
+
+	// Free query plan.
+	query_plan_free(*query_plan);
+	*query_plan = NULL;
+
+	// Free query modules list.
+	knotd_mod_t *mod, *next;
+	WALK_LIST_DELSAFE(mod, next, *query_modules) {
+		if (mod->api->unload != NULL) {
+			mod->api->unload(mod);
+		}
+		query_module_close(mod);
+	}
+	init_list(query_modules);
+}
+
+void conf_reset_modules(
+	conf_t *conf,
+	list_t *query_modules,
+	struct query_plan **query_plan)
+{
+	if (query_modules == NULL || query_plan == NULL) {
+		return;
+	}
+
+	struct query_plan *new_plan = query_plan_create();
+	if (new_plan == NULL) {
+		CONF_LOG(LOG_ERR, "failed to activate modules (%s)", knot_strerror(KNOT_ENOMEM));
+		return;
+	}
+
+	struct query_plan *old_plan = rcu_xchg_pointer(query_plan, NULL);
+	synchronize_rcu();
+	query_plan_free(old_plan);
+
+	knotd_mod_t *mod;
+	WALK_LIST(mod, *query_modules) {
+		if (mod->api->unload != NULL) {
+			mod->api->unload(mod);
+		}
+		query_module_reset(conf, mod, new_plan);
+	}
+
+	knotd_mod_t *next;
+	WALK_LIST_DELSAFE(mod, next, *query_modules) {
+		int ret = mod->api->load(mod);
+		if (ret != KNOT_EOK) {
+			MOD_ID_LOG(mod->zone, error, mod->id, "failed to load (%s)",
+			           knot_strerror(ret));
+			rem_node(&mod->node);
+			query_module_close(mod);
+			continue;
+		}
+		mod->config = NULL; // Invalidate the current config.
+	}
+
+	(void)rcu_xchg_pointer(query_plan, new_plan);
+}