!404 DNS解析接口，在无网络情况下立刻返回

Merge pull request !404 from maosiping/master

src/network/lookup_name.c

@@ -173,7 +173,8 @@ static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[
 	size_t l, dots;
 	char *p, *z;
 
-	if (__get_resolv_conf(&conf, search, sizeof search) < 0) return -1;
+	int res = __get_resolv_conf(&conf, search, sizeof search);
+	if (res < 0) return res;
 
 	/* Count dots, suppress search when >=ndots or name ends in
 	 * a dot, which is an explicit request for global scope. */

src/network/resolvconf.c

@@ -40,12 +40,10 @@ int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
 	dlclose(handle);
 	if (ret < 0) {
 		DNS_CONFIG_PRINT("__get_resolv_conf OHOS_GET_CONFIG_FUNC_NAME err %d\n", ret);
-		goto etc_resolv_conf;
+		return EAI_NONAME;
 	}
 	int32_t timeout_second = config.timeout_ms / 1000;
-#endif
 
-#if OHOS_DNS_PROXY_BY_NETSYS
 netsys_conf:
 	if (timeout_second > 0) {
 		if (timeout_second >= 60) {