Do not send excessive DNS queries for online checks (#2100) (#2101)

* Do not send excessive DNS queries for online checks (#2100)

buildroot-external/patches/network-manager/0001-connectivity-handle-NoNameServers-resolved-error-and.patch

@@ -0,0 +1,46 @@
+From 88f63699c444e43096e765b2603aa211a8ae58bb Mon Sep 17 00:00:00 2001
+Message-Id: <88f63699c444e43096e765b2603aa211a8ae58bb.1661980860.git.stefan@agner.ch>
+From: Thomas Haller <thaller@redhat.com>
+Date: Fri, 8 Apr 2022 15:33:39 +0200
+Subject: [PATCH] connectivity: handle "NoNameServers" resolved error and don't
+ callback to system resolver
+
+No need to try further. The verdict is clear.
+
+From the log:
+
+  <debug> [1649424031.1507] connectivity: (wlan0,IPv4,427) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
+  <debug> [1649424031.1507] connectivity: (wlan0,IPv4,427) start request to 'http://fedoraproject.org/static/hotspot.txt' (try resolving 'fedoraproject.org' using system resolver)
+
+(cherry picked from commit 5b779c1ab7fb53857db235383af8274ab824a55e)
+(altered to apply to 1.34.0)
+---
+ src/core/nm-connectivity.c | 11 ++++++++++-
+ 1 file changed, 10 insertions(+), 1 deletion(-)
+
+diff --git a/src/core/nm-connectivity.c b/src/core/nm-connectivity.c
+index 13fb026514..3e4914ee3b 100644
+--- a/src/core/nm-connectivity.c
++++ b/src/core/nm-connectivity.c
+@@ -719,8 +719,17 @@ resolve_cb(GObject *object, GAsyncResult *res, gpointer user_data)
+     g_clear_object(&cb_data->concheck.resolve_cancellable);
+ 
+     if (!result) {
+-        /* Never mind. Just let do curl do its own resolving. */
++        gs_free char *dbus_error = NULL;
++
+         _LOG2D("can't resolve a name via systemd-resolved: %s", error->message);
++
++        dbus_error = g_dbus_error_get_remote_error(error);
++        if (nm_streq0(dbus_error, "org.freedesktop.resolve1.NoNameServers")) {
++            cb_data_complete(cb_data, NM_CONNECTIVITY_LIMITED, "resolve-error");
++            return;
++        }
++
++        /* Never mind. Just let do curl do its own resolving. */
+         do_curl_request(cb_data);
+         return;
+     }
+-- 
+2.37.2
+