data.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2009, Eliel C. Sardanons (LU1ALY) <eliels@gmail.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Data retrieval API.
 *
 * \author Brett Bryant <brettbryant@gmail.com>
 * \author Eliel C. Sardanons (LU1ALY) <eliels@gmail.com>
 */

/*** MODULEINFO
	<support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/_private.h"

#include <regex.h>

#include "asterisk/module.h"
#include "asterisk/utils.h"
#include "asterisk/lock.h"
#include "asterisk/data.h"
#include "asterisk/astobj2.h"
#include "asterisk/xml.h"
#include "asterisk/cli.h"
#include "asterisk/term.h"
#include "asterisk/manager.h"
#include "asterisk/test.h"
#include "asterisk/frame.h"
#include "asterisk/codec.h"

/*** DOCUMENTATION
	<manager name="DataGet" language="en_US">
		<synopsis>
			Retrieve the data api tree.
		</synopsis>
		<syntax>
			<xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
			<parameter name="Path" required="true" />
			<parameter name="Search" />
			<parameter name="Filter" />
		</syntax>
		<description>
			<para>Retrieve the data api tree.</para>
		</description>
	</manager>
 ***/

#define NUM_DATA_NODE_BUCKETS	59
#define NUM_DATA_RESULT_BUCKETS 59
#define NUM_DATA_SEARCH_BUCKETS 59
#define NUM_DATA_FILTER_BUCKETS 59

/*! \brief The last compatible version. */
static const uint32_t latest_handler_compatible_version = 0;

/*! \brief The last compatible version. */
static const uint32_t latest_query_compatible_version = 0;

/*! \brief Current handler structure version. */
static const uint32_t current_handler_version = AST_DATA_HANDLER_VERSION;

/*! \brief Current query structure version. */
static const uint32_t current_query_version = AST_DATA_QUERY_VERSION;

/*! \brief The data tree to be returned by the callbacks and
	   managed by functions local to this file. */
struct ast_data {
	enum ast_data_type type;

	/*! \brief The node content. */
	union {
		int32_t sint;
		uint32_t uint;
		double dbl;
		unsigned int boolean;
		char *str;
		char character;
		struct in_addr ipaddr;
		void *ptr;
	} payload;

	/*! \brief The filter node that depends on the current node,
	 * this is used only when creating the result tree. */
	const struct data_filter *filter;

	/*! \brief The list of nodes inside this node. */
	struct ao2_container *children;
	/*! \brief The name of the node. */
	char name[0];
};

/*! \brief Type of comparisons allow in the search string. */
enum data_search_comparison {
	DATA_CMP_UNKNOWN,
	DATA_CMP_EQ,	/* =  */
	DATA_CMP_NEQ,	/* != */
	DATA_CMP_GT,	/* >  */
	DATA_CMP_GE,	/* >= */
	DATA_CMP_LT,	/* <  */
	DATA_CMP_LE	/* <= */
};

/*! \brief The list of nodes with their search requirement. */
struct ast_data_search {
	/*! \brief The value of the comparison. */
	char *value;
	/*! \brief The type of comparison. */
	enum data_search_comparison cmp_type;
	/*! \brief reference another node. */
	struct ao2_container *children;
	/*! \brief The name of the node we are trying to compare. */
	char name[0];
};

struct data_filter;

/*! \brief The filter node. */
struct data_filter {
	/*! \brief node childrens. */
	struct ao2_container *children;
	/*! \brief glob list */
	AST_LIST_HEAD_NOLOCK(glob_list_t, data_filter) glob_list;
	/*! \brief glob list entry */
	AST_LIST_ENTRY(data_filter) list;
	/*! \brief node name. */
	char name[0];
};

/*! \brief A data container node pointing to the registered handler. */
struct data_provider {
	/*! \brief node content handler. */
	const struct ast_data_handler *handler;
	/*! \brief Module providing this handler. */
	struct ast_module *module;
	/*! \brief children nodes. */
	struct ao2_container *children;
	/*! \brief Who registered this node. */
	const char *registrar;
	/*! \brief Node name. */
	char name[0];
};

/*! \brief This structure is used by the iterator. */
struct ast_data_iterator {
	/*! \brief The internal iterator. */
	struct ao2_iterator internal_iterator;
	/*! \brief The last returned node. */
	struct ast_data *last;
	/*! \brief The iterator pattern. */
	const char *pattern;
	/*! \brief The compiled patter. */
	regex_t regex_pattern;
	/*! \brief is a regular expression. */
	unsigned int is_pattern:1;
};

struct {
	/*! \brief The asterisk data main content structure. */
	struct ao2_container *container;
	/*! \brief asterisk data locking mechanism. */
	ast_rwlock_t lock;
} root_data;

static void __data_result_print_cli(int fd, const struct ast_data *root, uint32_t depth);

/*!
 * \internal
 * \brief Common string hash function.
 * \see ast_data_init
 */
static int data_provider_hash(const void *obj, const int flags)
{
	const struct data_provider *node = obj;
	return ast_str_case_hash(node->name);
}

/*!
 * \internal
 * \brief Compare two data_provider's.
 * \see ast_data_init
 */
static int data_provider_cmp(void *obj1, void *obj2, int flags)
{
	struct data_provider *node1 = obj1, *node2 = obj2;
	return strcasecmp(node1->name, node2->name) ? 0 : CMP_MATCH;
}

/*!
 * \internal
 * \brief Common string hash function for data nodes
 */
static int data_result_hash(const void *obj, const int flags)
{
	const struct ast_data *node = obj;
	return ast_str_hash(node->name);
}

/*!
 * \internal
 * \brief Common string comparison function
 */
static int data_result_cmp(void *obj, void *arg, int flags)
{
	struct ast_data *node1 = obj, *node2 = arg;
	return strcasecmp(node1->name, node2->name) ? 0 : CMP_MATCH;
}

/*!
 * \internal
 * \brief Lock the data registered handlers structure for writing.
 * \see data_unlock
 */
#define data_write_lock() ast_rwlock_wrlock(&root_data.lock)

/*!
 * \internal
 * \brief Lock the data registered handlers structure for reading.
 * \see data_unlock
 */
#define data_read_lock() ast_rwlock_rdlock(&root_data.lock)

/*!
 * \internal
 * \brief Unlock the data registered handlers structure.
 */
#define data_unlock() ast_rwlock_unlock(&root_data.lock)

/*!
 * \internal
 * \brief Check if a version is compatible with the current core.
 * \param[in] structure_version The current structure version.
 * \param[in] latest_compatible The latest compatible version.
 * \param[in] current The current Data API version.
 * \retval 1 If the module is compatible.
 * \retval 0 If the module is NOT compatible.
 */
static int data_structure_compatible(int structure_version, uint32_t latest_compatible,
	uint32_t current)
{
	if (structure_version >= latest_compatible && structure_version <= current) {
		return 1;
	}

	ast_log(LOG_ERROR, "A module is not compatible with the"
		"current data api version\n");

	return 0;
}

/*!
 * \internal
 * \brief Get the next node name in a path (/node1/node2)
 *        Avoid null nodes like //node1//node2/node3.
 * \param[in] path The path where we are going to search for the next node name.
 * \retval The next node name we found inside the given path.
 * \retval NULL if there are no more node names.
 */
static char *next_node_name(char **path)
{
	char *res;

	do {
		res = strsep(path, "/");
	} while (res && ast_strlen_zero(res));

	return res;
}

/*!
 * \internal
 * \brief Release the memory allocated by a call to ao2_alloc.
 */
static void data_provider_destructor(void *obj)
{
	struct data_provider *provider = obj;

	ao2_ref(provider->children, -1);
}

/*!
 * \internal
 * \brief Create a new data node.
 * \param[in] name The name of the node we are going to create.
 * \param[in] handler The handler registered for this node.
 * \param[in] registrar The name of the registrar.
 * \retval NULL on error.
 * \retval The allocated data node structure.
 */
static struct data_provider *data_provider_new(const char *name,
	const struct ast_data_handler *handler, const char *registrar)
{
	struct data_provider *node;
	size_t namelen;

	namelen = strlen(name) + 1;

	node = ao2_alloc(sizeof(*node) + namelen, data_provider_destructor);
	if (!node) {
		return NULL;
	}

	node->handler = handler;
	node->registrar = registrar;
	strcpy(node->name, name);

	/* initialize the childrens container. */
	if (!(node->children = ao2_container_alloc(NUM_DATA_NODE_BUCKETS,
			data_provider_hash, data_provider_cmp))) {
		ao2_ref(node, -1);
		return NULL;
	}

	return node;
}

/*!
 * \internal
 * \brief Add a child node named 'name' to the 'parent' node.
 * \param[in] parent Where to add the child node.
 * \param[in] name The name of the child node.
 * \param[in] handler The handler structure.
 * \param[in] registrar Who registered this node.
 * \retval NULL on error.
 * \retval A newly allocated child in parent.
 */
static struct data_provider *data_provider_add_child(struct ao2_container *parent,
	const char *name, const struct ast_data_handler *handler, const char *registrar)
{
	struct data_provider *child;

	child = data_provider_new(name, handler, registrar);
	if (!child) {
		return NULL;
	}

	ao2_link(parent, child);

	return child;
}

/*!
 * \internal
 * \brief Find a child node, based on his name.
 * \param[in] parent Where to find the node.
 * \param[in] name The node name to find.
 * \param[in] registrar Also check if the node was being used by this registrar.
 * \retval NULL if a node wasn't found.
 * \retval The node found.
 * \note Remember to decrement the ref count of the returned node after using it.
 */
static struct data_provider *data_provider_find(struct ao2_container *parent,
	const char *name, const char *registrar)
{
	struct data_provider *find_node, *found;

	/* XXX avoid allocating a new data node for searching... */
	find_node = data_provider_new(name, NULL, NULL);
	if (!find_node) {
		return NULL;
	}

	found = ao2_find(parent, find_node, OBJ_POINTER);

	/* free the created node used for searching. */
	ao2_ref(find_node, -1);

	if (found && found->registrar && registrar) {
		if (strcmp(found->registrar, registrar)) {
			/* if the name doesn't match, do not return this node. */
			ast_debug(1, "Registrar doesn't match, node was registered"
				" by '%s' and we are searching for '%s'\n",
				found->registrar, registrar);
			ao2_ref(found, -1);
			return NULL;
		}
	}

	return found;
}

/*!
 * \internal
 * \brief Release a group of nodes.
 * \param[in] parent The parent node.
 * \param[in] path The path of nodes to release.
 * \param[in] registrar Who registered this node.
 * \retval <0 on error.
 * \retval 0 on success.
 * \see data_provider_create
 */
static int data_provider_release(struct ao2_container *parent, const char *path,
	const char *registrar)
{
	char *node_name, *rpath;
	struct data_provider *child;
	int ret = 0;

	rpath = ast_strdupa(path);

	node_name = next_node_name(&rpath);
	if (!node_name) {
		return -1;
	}

	child = data_provider_find(parent, node_name, registrar);
	if (!child) {
		return -1;
	}

	/* if this is not a terminal node. */
	if (!child->handler && rpath) {
		ret = data_provider_release(child->children, rpath, registrar);
	}

	/* if this node is empty, unlink it. */
	if (!ret && !ao2_container_count(child->children)) {
		ao2_unlink(parent, child);
	}

	ao2_ref(child, -1);

	return ret;
}

/*!
 * \internal
 * \brief Release every node registered by 'registrar'.
 * \param[in] parent The parent node.
 * \param[in] registrar
 * \see __ast_data_unregister
 */
static void data_provider_release_all(struct ao2_container *parent,
	const char *registrar)
{
	struct ao2_iterator i;
	struct data_provider *node;

	i = ao2_iterator_init(parent, 0);
	while ((node = ao2_iterator_next(&i))) {
		if (!node->handler) {
			/* this is a non-terminal node, go inside it. */
			data_provider_release_all(node->children, registrar);
			if (!ao2_container_count(node->children)) {
				/* if this node was left empty, unlink it. */
				ao2_unlink(parent, node);
			}
		} else {
			if (!strcmp(node->registrar, registrar)) {
				/* if the registrars match, release it! */
				ao2_unlink(parent, node);
			}
		}
		ao2_ref(node, -1);
	}
	ao2_iterator_destroy(&i);

}

/*!
 * \internal
 * \brief Create the middle nodes for the specified path (asterisk/testnode1/childnode)
 * \param[in] parent Where to add the middle nodes structure.
 * \param[in] path The path of nodes to add.
 * \param[in] registrar Who is trying to create this node provider.
 * \retval NULL on error.
 * \retval The created node.
 * \see data_provider_release
 */
static struct data_provider *data_provider_create(struct ao2_container *parent,
	const char *path, const char *registrar)
{
	char *rpath, *node_name;
	struct data_provider *child, *ret = NULL;

	rpath = ast_strdupa(path);

	node_name = next_node_name(&rpath);
	if (!node_name) {
		/* no more nodes to create. */
		return NULL;
	}

	child = data_provider_find(parent, node_name, NULL);

	if (!child) {
		/* nodes without handler are non-terminal nodes. */
		child = data_provider_add_child(parent, node_name, NULL, registrar);
	}

	if (rpath) {
		ret = data_provider_create(child->children, rpath, registrar);
		if (ret) {
			ao2_ref(child, -1);
		}
	}

	return ret ? ret : child;
}

int __ast_data_register(const char *path, const struct ast_data_handler *handler,
	const char *registrar, struct ast_module *mod)
{
	struct data_provider *node;

	if (!path) {
		return -1;
	}

	/* check if the handler structure is compatible. */
	if (!data_structure_compatible(handler->version,
		latest_handler_compatible_version,
		current_handler_version)) {
		return -1;
	}

	/* create the node structure for the registered handler. */
	data_write_lock();

	node = data_provider_create(root_data.container, path, registrar);
	if (!node) {
		ast_log(LOG_ERROR, "Unable to create the specified path (%s) "
			"for '%s'.\n", path, registrar);
		data_unlock();
		return -1;
	}

	if (ao2_container_count(node->children) || node->handler) {
		ast_log(LOG_ERROR, "The node '%s' was already registered. "
			"We were unable to register '%s' for registrar '%s'.\n",
			node->name, path, registrar);
		ao2_ref(node, -1);
		data_unlock();
		return -1;
	}

	/* add handler to that node. */
	node->handler = handler;
	node->module = mod;

	ao2_ref(node, -1);

	data_unlock();

	return 0;
}

int __ast_data_register_multiple(const struct ast_data_entry *data_entries,
	size_t entries, const char *registrar, struct ast_module *mod)
{
	int i, res;

	for (i = 0; i < entries; i++) {
		res = __ast_data_register(data_entries[i].path, data_entries[i].handler,
				registrar, mod);
		if (res) {
			/* unregister all the already registered nodes, and make
			 * this an atomic action. */
			while ((--i) >= 0) {
				__ast_data_unregister(data_entries[i].path, registrar);
			}
			return -1;
		}
	}

	return 0;
}

int __ast_data_unregister(const char *path, const char *registrar)
{
	int ret = 0;

	data_write_lock();
	if (path) {
		ret = data_provider_release(root_data.container, path, registrar);
	} else {
		data_provider_release_all(root_data.container, registrar);
	}
	data_unlock();

	if (path && ret) {
		ast_log(LOG_ERROR, "Unable to unregister '%s' for '%s'\n",
			path, registrar);
	}

	return ret;
}

/*!
 * \internal
 * \brief Is a char used to specify a comparison?
 * \param[in] a Character to evaluate.
 * \retval 1 It is a char used to specify a comparison.
 * \retval 0 It is NOT a char used to specify a comparison.
 */
static int data_search_comparison_char(char a)
{
	switch (a) {
	case '!':
	case '=':
	case '<':
	case '>':
		return 1;
	}

	return 0;
}

/*!
 * \internal
 * \brief Get the type of comparison.
 */
static enum data_search_comparison data_search_comparison_type(const char *comparison)
{
	if (!strcmp(comparison, "=")) {
		return DATA_CMP_EQ;
	} else if (!strcmp(comparison, "!=")) {
		return DATA_CMP_NEQ;
	} else if (!strcmp(comparison, "<")) {
		return DATA_CMP_LT;
	} else if (!strcmp(comparison, ">")) {
		return DATA_CMP_GT;
	} else if (!strcmp(comparison, "<=")) {
		return DATA_CMP_LE;
	} else if (!strcmp(comparison, ">=")) {
		return DATA_CMP_GE;
	}

	return DATA_CMP_UNKNOWN;
}

/*!
 * \internal
 * \brief Common string hash function for data nodes
 */
static int data_search_hash(const void *obj, const int flags)
{
	const struct ast_data_search *node = obj;
	return ast_str_hash(node->name);
}

/*!
 * \internal
 * \brief Common string comparison function
 */
static int data_search_cmp(void *obj, void *arg, int flags)
{
	struct ast_data_search *node1 = obj, *node2 = arg;
	return strcasecmp(node1->name, node2->name) ? 0 : CMP_MATCH;
}

/*!
 * \internal
 * \brief Destroy the ao2 search node.
 */
static void data_search_destructor(void *obj)
{
	struct ast_data_search *node = obj;

	if (node->value) {
		ast_free(node->value);
	}

	ao2_ref(node->children, -1);
}

/*!
 * \internal
 * \brief Allocate a search node.
 * \retval NULL on error.
 * \retval non-NULL The allocated search node structure.
 */
static struct ast_data_search *data_search_alloc(const char *name)
{
	struct ast_data_search *res;
	size_t name_len = strlen(name) + 1;

	res = ao2_alloc(sizeof(*res) + name_len, data_search_destructor);
	if (!res) {
		return NULL;
	}

	res->children = ao2_container_alloc(NUM_DATA_SEARCH_BUCKETS, data_search_hash,
		data_search_cmp);

	if (!res->children) {
		ao2_ref(res, -1);
		return NULL;
	}

	strcpy(res->name, name);

	return res;
}

/*!
 * \internal
 * \brief Find a child node, based on his name.
 * \param[in] parent Where to find the node.
 * \param[in] name The node name to find.
 * \retval NULL if a node wasn't found.
 * \retval The node found.
 * \note Remember to decrement the ref count of the returned node after using it.
 */
static struct ast_data_search *data_search_find(struct ao2_container *parent,
	const char *name)
{
	struct ast_data_search *find_node, *found;

	find_node = data_search_alloc(name);
	if (!find_node) {
		return NULL;
	}

	found = ao2_find(parent, find_node, OBJ_POINTER);

	/* free the created node used for searching. */
	ao2_ref(find_node, -1);

	return found;
}

/*!
 * \internal
 * \brief Add a child node named 'name' to the 'parent' node.
 * \param[in] parent Where to add the child node.
 * \param[in] name The name of the child node.
 * \retval NULL on error.
 * \retval A newly allocated child in parent.
 */
static struct ast_data_search *data_search_add_child(struct ao2_container *parent,
	const char *name)
{
	struct ast_data_search *child;

	child = data_search_alloc(name);
	if (!child) {
		return NULL;
	}

	ao2_link(parent, child);

	return child;
}

/*!
 * \internal
 * \brief Create the middle nodes for the specified path (asterisk/testnode1/childnode)
 * \param[in] parent Where to add the middle nodes structure.
 * \param[in] path The path of nodes to add.
 * \retval NULL on error.
 * \retval The created node.
 */
static struct ast_data_search *data_search_create(struct ao2_container *parent,
	const char *path)
{
	char *rpath, *node_name;
	struct ast_data_search *child = NULL;
	struct ao2_container *current = parent;

	rpath = ast_strdupa(path);

	node_name = next_node_name(&rpath);
	while (node_name) {
		child = data_search_find(current, node_name);
		if (!child) {
			child = data_search_add_child(current, node_name);
		}
		ao2_ref(child, -1);
		current = child->children;
		node_name = next_node_name(&rpath);
	}

	return child;
}

/*!
 * \internal
 * \brief Allocate a tree with the search string parsed.
 * \param[in] search_string The search string.
 * \retval NULL on error.
 * \retval non-NULL A dynamically allocated search tree.
 */
static struct ast_data_search *data_search_generate(const char *search_string)
{
	struct ast_str *name, *value, *comparison;
	char *elements, *search_string_dup, *saveptr;
	int i;
	struct ast_data_search *root, *child;
	enum data_search_comparison cmp_type;
	size_t search_string_len;

	if (!search_string) {
		ast_log(LOG_ERROR, "You must pass a valid search string.\n");
		return NULL;
	}

	search_string_len = strlen(search_string);

	name = ast_str_create(search_string_len);
	if (!name) {
		return NULL;
	}
	value = ast_str_create(search_string_len);
	if (!value) {
		ast_free(name);
		return NULL;
	}
	comparison = ast_str_create(search_string_len);
	if (!comparison) {
		ast_free(name);
		ast_free(value);
		return NULL;
	}

	search_string_dup = ast_strdupa(search_string);

	/* Create the root node (just used as a container) */
	root = data_search_alloc("/");
	if (!root) {
		ast_free(name);
		ast_free(value);
		ast_free(comparison);
		return NULL;
	}

	for (elements = strtok_r(search_string_dup, ",", &saveptr); elements;
		elements = strtok_r(NULL, ",", &saveptr)) {
		/* Parse the name */
		ast_str_reset(name);
		for (i = 0; !data_search_comparison_char(elements[i]) &&
			elements[i]; i++) {
			ast_str_append(&name, 0, "%c", elements[i]);
		}

		/* check if the syntax is ok. */
		if (!data_search_comparison_char(elements[i])) {
			/* if this is the end of the string, then this is
			 * an error! */
			ast_log(LOG_ERROR, "Invalid search string!\n");
			continue;
		}

		/* parse the comparison string. */
		ast_str_reset(comparison);
		for (; data_search_comparison_char(elements[i]) && elements[i]; i++) {
			ast_str_append(&comparison, 0, "%c", elements[i]);
		}

		/* parse the value string. */
		ast_str_reset(value);
		for (; elements[i]; i++) {
			ast_str_append(&value, 0, "%c", elements[i]);
		}

		cmp_type = data_search_comparison_type(ast_str_buffer(comparison));
		if (cmp_type == DATA_CMP_UNKNOWN) {
			ast_log(LOG_ERROR, "Invalid comparison '%s'\n",
				ast_str_buffer(comparison));
			continue;
		}

		/* add this node to the tree. */
		child = data_search_create(root->children, ast_str_buffer(name));
		if (child) {
			child->cmp_type = cmp_type;
			child->value = ast_strdup(ast_str_buffer(value));
		}
	}

	ast_free(name);
	ast_free(value);
	ast_free(comparison);

	return root;
}

/*!
 * \internal
 * \brief Release the allocated memory for the search tree.
 * \param[in] search The search tree root node.
 */
static void data_search_release(struct ast_data_search *search)
{
	ao2_ref(search, -1);
}

/*!
 * \internal
 * \brief Based on the kind of comparison and the result in cmpval, return
 *        if it matches.
 * \param[in] cmpval A result returned by a strcmp() for example.
 * \param[in] comparison_type The kind of comparison (<,>,=,!=,...)
 * \retval 1 If the comparison doesn't match.
 * \retval 0 If the comparison matches.
 */
static inline int data_search_comparison_result(int cmpval,
	enum data_search_comparison comparison_type)
{
	switch (comparison_type) {
	case DATA_CMP_GE:
		if (cmpval >= 0) {
			return 0;
		}
		break;
	case DATA_CMP_LE:
		if (cmpval <= 0) {
			return 0;
		}
		break;
	case DATA_CMP_EQ:
		if (cmpval == 0) {
			return 0;
		}
		break;
	case DATA_CMP_NEQ:
		if (cmpval != 0) {
			return 0;
		}
		break;
	case DATA_CMP_LT:
		if (cmpval < 0) {
			return 0;
		}
		break;
	case DATA_CMP_GT:
		if (cmpval > 0) {
			return 0;
		}
		break;
	case DATA_CMP_UNKNOWN:
		break;
	}
	return 1;
}

/*!
 * \internal
 * \brief Get an internal node, from the search tree.
 * \param[in] node A node container.
 * \param[in] path The path to the needed internal node.
 * \retval NULL if the internal node is not found.
 * \retval non-NULL the internal node with path 'path'.
 */
static struct ast_data_search *data_search_get_node(const struct ast_data_search *node,
	const char *path)
{
	char *savepath, *node_name;
	struct ast_data_search *child, *current = (struct ast_data_search *) node;

	if (!node) {
		return NULL;
	}

	savepath = ast_strdupa(path);
	node_name = next_node_name(&savepath);

	while (node_name) {
		child = data_search_find(current->children, node_name);
		if (current != node) {
			ao2_ref(current, -1);
		}
		if (!child) {
			return NULL;
		};
		current = child;
		node_name = next_node_name(&savepath);
	}

	return current;
}

/*!
 * \internal
 * \brief Based on a search tree, evaluate the specified 'name' inside the tree with the
 *        current string value.
 *        .search = "somename=somestring"
 *        name = "somename"
 *        value is the current value of something and will be evaluated against "somestring".
 * \param[in] root The root node pointer of the search tree.
 * \param[in] name The name of the specific.
 * \param[in] value The value to compare.