names, network: Re-feed DNS known to network-manager to resolved

- This avoids using fallback DNS servers in systemd-resolved soon after
systemd-resolved takes over /etc/resolv.conf and if network-manager knows some
DNS servers from the connections it has established.

- Version for the names app has already been incremented in this patch series.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Veiko Aasa <veiko17@disroot.org>

plinth/modules/names/__init__.py

@@ -8,7 +8,7 @@ import logging
 from django.utils.translation import gettext_lazy as _
 
 from plinth import app as app_module
-from plinth import cfg, menu
+from plinth import cfg, menu, network
 from plinth.daemon import Daemon
 from plinth.modules.backups.components import BackupRestore
 from plinth.package import Packages
@@ -82,6 +82,15 @@ class NamesApp(app_module.App):
         # FreedomBox.
         service_privileged.restart('systemd-resolved')
 
+        # After systemd-resolved is freshly installed, /etc/resolve.conf
+        # becomes a symlink to configuration pointing to systemd-resovled stub
+        # resolver. However, the old contents are not fed from network-manager
+        # (if it was present earlier and wrote to /etc/resolve.conf). Ask
+        # network-manager to feed the DNS servers from the connections it has
+        # established to systemd-resolved so that using fallback DNS servers is
+        # not necessary.
+        network.refeed_dns()
+
         self.enable()
 
 

plinth/network.py

@@ -622,3 +622,8 @@ def wifi_scan():
             })
 
     return access_points
+
+
+def refeed_dns():
+    """Re-feed DNS servers to systemd-resolved."""
+    get_nm_client().reload(nm.ManagerReloadFlags.DNS_RC)