dns: Add core DNS API + unit tests and res_resolver_unbound module + unit tests.

This change adds an abstracted core DNS API which resembles the API described
here[1]. The API provides a pluggable mechanism for resolvers and also a
consistent view for records. Both synchronous and asynchronous queries are
supported.

This change also adds a res_resolver_unbound module which uses the libunbound
library to provide resolution.

Unit tests have also been written for all of the above to confirm the API and
functionality.

ASTERISK-24834 #close
Reported by: Matt Jordan

ASTERISK-24836 #close
Reported by: Matt Jordan

Review: https://reviewboard.asterisk.org/r/4474/
Review: https://reviewboard.asterisk.org/r/4512/

[1] https://wiki.asterisk.org/wiki/display/AST/Asterisk+DNS+API


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@433370 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/dns_query_set.c

@@ -0,0 +1,93 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, Digium, Inc.
+ *
+ * Joshua Colp <jcolp@digium.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 DNS Query Set API
+ *
+ * \author Joshua Colp <jcolp@digium.com>
+ */
+
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/vector.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/dns_core.h"
+#include "asterisk/dns_query_set.h"
+
+/*! \brief A set of DNS queries */
+struct ast_dns_query_set {
+	/*! \brief DNS queries */
+	AST_VECTOR(, struct ast_dns_query *) queries;
+	/*! \brief The total number of completed queries */
+	unsigned int queries_completed;
+	/*! \brief Callback to invoke upon completion */
+	ast_dns_query_set_callback callback;
+	/*! \brief User-specific data */
+	void *user_data;
+};
+
+struct ast_dns_query_set *ast_dns_query_set_create(void)
+{
+	return NULL;
+}
+
+int ast_dns_query_set_add(struct ast_dns_query_set *query_set, const char *name, int rr_type, int rr_class)
+{
+	return -1;
+}
+
+size_t ast_dns_query_set_num_queries(const struct ast_dns_query_set *query_set)
+{
+	return 0;
+}
+
+struct ast_dns_query *ast_dns_query_set_get(const struct ast_dns_query_set *query_set, unsigned int index)
+{
+	return NULL;
+}
+
+void *ast_dns_query_set_get_data(const struct ast_dns_query_set *query_set)
+{
+	return query_set->user_data;
+}
+
+void ast_dns_query_set_resolve_async(struct ast_dns_query_set *query_set, ast_dns_query_set_callback callback, void *data)
+{
+	query_set->callback = callback;
+	query_set->user_data = ao2_bump(data);
+}
+
+void ast_query_set_resolve(struct ast_dns_query_set *query_set)
+{
+}
+
+int ast_dns_query_set_resolve_cancel(struct ast_dns_query_set *query_set)
+{
+	return -1;
+}
+
+void ast_dns_query_set_free(struct ast_dns_query_set *query_set)
+{
+}