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

1 files changed, 267 insertions, 0 deletions

diff --git a/include/asterisk/dns_core.h b/include/asterisk/dns_core.h
new file mode 100644
index 000000000..1f67bb803
--- /dev/null
+++ b/include/asterisk/dns_core.h
@@ -0,0 +1,267 @@
+/*
+ * 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 Core DNS API
+ * \author Joshua Colp <jcolp@digium.com>
+ */
+
+#ifndef _ASTERISK_DNS_CORE_H
+#define _ASTERISK_DNS_CORE_H
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+/*! \brief Opaque structure for an active DNS query */
+struct ast_dns_query_active;
+
+/*! \brief Opaque structure for a DNS query */
+struct ast_dns_query;
+
+/*!
+ * \brief Get the name queried in a DNS query
+ *
+ * \param query The DNS query
+ *
+ * \return the name queried
+ */
+const char *ast_dns_query_get_name(const struct ast_dns_query *query);
+
+/*!
+ * \brief Get the record resource type of a DNS query
+ *
+ * \param query The DNS query
+ *
+ * \return the record resource type
+ */
+int ast_dns_query_get_rr_type(const struct ast_dns_query *query);
+
+/*!
+ * \brief Get the record resource class of a DNS query
+ *
+ * \param query The DNS query
+ *
+ * \return the record resource class
+ */
+int ast_dns_query_get_rr_class(const struct ast_dns_query *query);
+
+/*!
+ * \brief Get the user specific data of a DNS query
+ *
+ * \param query The DNS query
+ *
+ * \return the user specific data
+ *
+ * \note The reference count of the data is NOT incremented on return
+ */
+void *ast_dns_query_get_data(const struct ast_dns_query *query);
+
+/*! \brief Opaque structure for a DNS query result, guaranteed to be immutable */
+struct ast_dns_result;
+
+/*!
+ * \brief Get the result information for a DNS query
+ *
+ * \param query The DNS query
+ *
+ * \return the DNS result information
+ *
+ * \note The result is NOT ao2 allocated
+ */
+struct ast_dns_result *ast_dns_query_get_result(const struct ast_dns_query *query);
+
+/*!
+ * \brief Get whether the result is secure or not
+ *
+ * \param result The DNS result
+ *
+ * \return whether the result is secure or not
+ */
+unsigned int ast_dns_result_get_secure(const struct ast_dns_result *result);
+
+/*!
+ * \brief Get whether the result is bogus or not
+ *
+ * \param result The DNS result
+ *
+ * \return whether the result is bogus or not
+ */
+unsigned int ast_dns_result_get_bogus(const struct ast_dns_result *result);
+
+/*!
+ * \brief Get the error rcode of a DN result
+ *
+ * \param query The DNS result
+ *
+ * \return the DNS rcode
+ */
+unsigned int ast_dns_result_get_rcode(const struct ast_dns_result *result);
+
+/*!
+ * \brief Get the canonical name of the result
+ *
+ * \param result The DNS result
+ *
+ * \return the canonical name
+ */
+const char *ast_dns_result_get_canonical(const struct ast_dns_result *result);
+
+/*!
+ * \brief Get the first record of a DNS Result
+ *
+ * \param result The DNS result
+ *
+ * \return first DNS record
+ */
+const struct ast_dns_record *ast_dns_result_get_records(const struct ast_dns_result *result);
+
+/*!
+ * \brief Get the raw DNS answer from a DNS result
+ *
+ * \param result The DNS result
+ *
+ * \return The DNS result
+ */
+const char *ast_dns_result_get_answer(const struct ast_dns_result *result);
+
+/*!
+ * \brief Retrieve the lowest TTL from a result
+ *
+ * \param result The DNS result
+ *
+ * \return the lowest TTL
+ *
+ * \note If no records exist this function will return a TTL of 0
+ */
+int ast_dns_result_get_lowest_ttl(const struct ast_dns_result *result);
+
+/*!
+ * \brief Free the DNS result information
+ *
+ * \param result The DNS result
+ */
+void ast_dns_result_free(struct ast_dns_result *result);
+
+/*! \brief Opaque structure for a DNS record */
+struct ast_dns_record;
+
+/*!
+ * \brief Callback invoked when a query completes
+ *
+ * \param query The DNS query that was invoked
+ */
+typedef void (*ast_dns_resolve_callback)(const struct ast_dns_query *query);
+
+/*!
+ * \brief Get the resource record type of a DNS record
+ *
+ * \param record The DNS record
+ *
+ * \return the resource record type
+ */
+int ast_dns_record_get_rr_type(const struct ast_dns_record *record);
+
+/*!
+ * \brief Get the resource record class of a DNS record
+ *
+ * \param record The DNS record
+ *
+ * \return the resource record class
+ */
+int ast_dns_record_get_rr_class(const struct ast_dns_record *record);
+
+/*!
+ * \brief Get the TTL of a DNS record
+ *
+ * \param record The DNS record
+ *
+ * \return the TTL
+ */
+int ast_dns_record_get_ttl(const struct ast_dns_record *record);
+
+/*!
+ * \brief Retrieve the raw DNS record
+ *
+ * \param record The DNS record
+ *
+ * \return the raw DNS record
+ */
+const char *ast_dns_record_get_data(const struct ast_dns_record *record);
+
+/*!
+ * \brief Get the next DNS record
+ *
+ * \param record The current DNS record
+ *
+ * \return the next DNS record
+ */
+const struct ast_dns_record *ast_dns_record_get_next(const struct ast_dns_record *record);
+
+/*!
+ * \brief Asynchronously resolve a DNS query
+ *
+ * \param name The name of what to resolve
+ * \param rr_type Resource record type
+ * \param rr_class Resource record class
+ * \param callback The callback to invoke upon completion
+ * \param data User data to make available on the query
+ *
+ * \retval non-NULL success - query has been sent for resolution
+ * \retval NULL failure
+ *
+ * \note The result passed to the callback does not need to be freed
+ *
+ * \note The user data MUST be an ao2 object
+ *
+ * \note This function increments the reference count of the user data, it does NOT steal
+ *
+ * \note The active query must be released upon completion or cancellation using ao2_ref
+ */
+struct ast_dns_query_active *ast_dns_resolve_async(const char *name, int rr_type, int rr_class, ast_dns_resolve_callback callback, void *data);
+
+/*!
+ * \brief Cancel an asynchronous DNS resolution
+ *
+ * \param active The active DNS query returned from ast_dns_resolve_async
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ *
+ * \note If successfully cancelled the callback will not be invoked
+ */
+int ast_dns_resolve_cancel(struct ast_dns_query_active *active);
+
+/*!
+ * \brief Synchronously resolve a DNS query
+ *
+ * \param name The name of what to resolve
+ * \param rr_type Resource record type
+ * \param rr_class Resource record class
+ * \param result A pointer to hold the DNS result
+ *
+ * \retval 0 success - query was completed and result is available
+ * \retval -1 failure
+ */
+int ast_dns_resolve(const char *name, int rr_type, int rr_class, struct ast_dns_result **result);
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}
+#endif
+
+#endif /* _ASTERISK_DNS_CORE_H */