net: getaddrinfo: Query both IPv4 and IPv6 if family is AF_UNSPEC

We must query both IPv4 and IPv6 addresses if the hints parameter
is NULL i.e., user does not supply hints or if family is set to
AF_UNSPEC.

Fixes zephyrproject-rtos#16453

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

subsys/net/lib/sockets/getaddrinfo.c

@@ -105,7 +105,7 @@ static int exec_query(const char *host, int family,
 {
 	enum dns_query_type qtype = DNS_QUERY_TYPE_A;
 
-	if (IS_ENABLED(CONFIG_NET_IPV6) && family != AF_INET) {
+	if (IS_ENABLED(CONFIG_NET_IPV6) && family == AF_INET6) {
 		qtype = DNS_QUERY_TYPE_AAAA;
 	}
 
@@ -205,6 +205,7 @@ int z_impl_z_zsock_getaddrinfo_internal(const char *host, const char *service,
 	/* Link entries in advance */
 	ai_state.ai_arr[0].ai_next = &ai_state.ai_arr[1];
 
+	/* If the family is AF_UNSPEC, then we query IPv4 address first */
 	ret = exec_query(host, family, &ai_state);
 	if (ret == 0) {
 		/* If the DNS query for reason fails so that the
@@ -226,6 +227,26 @@ int z_impl_z_zsock_getaddrinfo_internal(const char *host, const char *service,
 		st1 = DNS_EAI_SYSTEM;
 	}
 
+	/* If family is AF_UNSPEC, the IPv4 query has been already done
+	 * so we can do IPv6 query next if IPv6 is enabled in the config.
+	 */
+	if (family == AF_UNSPEC && IS_ENABLED(CONFIG_NET_IPV6)) {
+		ret = exec_query(host, AF_INET6, &ai_state);
+		if (ret == 0) {
+			int ret = k_sem_take(&ai_state.sem,
+					     CONFIG_NET_SOCKETS_DNS_TIMEOUT +
+					     K_MSEC(100));
+			if (ret == -EAGAIN) {
+				return DNS_EAI_AGAIN;
+			}
+
+			st2 = ai_state.status;
+		} else {
+			errno = -ret;
+			st2 = DNS_EAI_SYSTEM;
+		}
+	}
+
 	if (ai_state.idx > 0) {
 		ai_addr = &ai_state.ai_arr[ai_state.idx - 1]._ai_addr;
 		net_sin(ai_addr)->sin_port = htons(port);