dns_core: Create new API ast_dns_resolve_ipv6_and_ipv4

The new function takes in a pointer to an ast_sockaddr structure,
a hostname and an optional port and then dispatches parallel
"AAAA" and "A" record queries.  If an "AAAA" record is returned,
it's parsed into the ast_sockaddr structure along with the port
if it was supplied.  If no "AAAA" record was returned, the
first "A" record returned (if any) is parsed instead.

This is a synchronous call.  If you need asynchronous lookups,
use ast_dns_query_set_resolve_async and roll your own.

Change-Id: I194b0b0e73da94b35cc35263a868ffac3a8d0a95

include/asterisk/dns_core.h

@@ -28,6 +28,8 @@
 extern "C" {
 #endif
 
+#include "asterisk/netsock2.h"
+
 /*! \brief Opaque structure for an active DNS query */
 struct ast_dns_query_active;
 
@@ -269,6 +271,26 @@ int ast_dns_resolve_cancel(struct ast_dns_query_active *active);
  */
 int ast_dns_resolve(const char *name, int rr_type, int rr_class, struct ast_dns_result **result);
 
+/*!
+ * \brief Synchronously resolves host to  an AAAA or A record
+ * \since 16.6.0
+ *
+ * \param address A pointer to an ast_sockaddr structure to receive the IPv6 or IPv4 address
+ * \param host The hostname to resolve
+ * \param port (optional) A port to parse into the final ast_sockaddr structure
+ *
+ * \retval 0 success - query was completed and result is available
+ * \retval -1 failure
+ *
+ * \note This function makes parallel queries for both AAAA and A records for the host.
+ * 		 The first returned AAAA record (if any) is used and if not found, the first A record
+ * 		 is used.
+ *
+ * \warning This function is synchronous and will block until records are returned or an error
+ *          occurrs.
+ */
+int ast_dns_resolve_ipv6_and_ipv4(struct ast_sockaddr *address, const char *host, const char *port);
+
 #if defined(__cplusplus) || defined(c_plusplus)
 }
 #endif